PROCESS FOR APPLICATION OF A METAL LAYER ON A SUBSTRATE

Abstract

The present invention relates to processes for application of a metal layer on a substrate via deposition of a metal from a metal salt solution by a chemical and/or electroplating method, a significant factor in these processes being that carbon nanotubes are present in the substrate surface. The present invention moreover relates to the use of carbon nanotubes for application of a metal layer on a substrate.

Description

The present invention relates to processes for application of a metal layer on a substrate via deposition of a metal from a metal salt solution, and also to the use of carbon nanotubes for application of a metal layer on a substrate.

Processes for metallizing materials which are usually electrically non-conductive, such as plastics, are known. These metallized parts, such as metallized plastics parts, are used in a wide variety of application sectors, and by way of example their electrical conductivity permits their use as electrical components. They are moreover widely used inter alia in the decorative sector, since while they have the same appearance as articles manufactured entirely from metal they have lower weight and can be produced at lower cost.

There are widely used processes for metallizing plastics where comparatively complicated pretreatment of the plastics surface is needed via chemical or physical roughening or chemical or physical etching processes, for example using chromic-sulfuric acid mixture, and/or with application of, for example, primer layers or adhesion-promoter layers comprising noble metals, as a precondition for deposition of coherent and firmly adhering metal layers by a currentless and/or electroplating method (see, for example, WO 01/77419).

Another known method for provision of plastics having electrical conductivity (this being a necessary precondition for metal deposition by an electroplating method) is incorporation of carbon nanotubes or carbon nanofibrils into plastic. Examples of other advantages of these electrically conductive carbon nanotubes are that they have lower weight than metal powders and that they usually give plastics increased toughness (see, for example, US 2006/0025515 A1).

DE 102 59 498 A1 discloses electrically conductive thermoplastics comprising not only a particulate carbon compound, such as carbon black or graphite, but also carbon nanofibrils. The plastics mixtures described in that document have not only electrical conductivity but good flowability, good surface quality, and also high toughness. They are particularly suitable for the electrostatic coating of plastics and for improving the electrostatic properties of plastics. However, the surface resistances disclosed in the specification are inadequate when the conductive thermoplastics are used as substrate in a process of metallizing by an electroplating method.

It is an object of the present invention to provide improved processes for application of a metal layer on a substrate via deposition of a metal from a metal salt solution by a chemical and/or electroplating method. Processes should in particular be made available in which metal layers can be deposited on a substrate with good adhesion to the substrate within comparatively short electroplating times, at low cost and with good quality, and in which the metallized substrates have comparatively low weight.

Accordingly, the processes mentioned in the introduction have been found for application of a metal layer on a substrate via deposition of a metal from a metal salt solution by a chemical and/or electroplating method, a significant factor in these processes being that carbon nanotubes are present in the substrate surface.

The use of carbon nanotubes has moreover been found for application of a metal layer on a substrate.

The inventive processes permit improved application of a metal layer on a substrate via deposition of a metal from a metal salt solution by a chemical and/or electroplating method. In particular, metal layers can be deposited on a substrate by the inventive processes with good adhesion to the substrate, within comparatively short electroplating times, at low cost and with good quality. The metallized substrates thus produced have comparatively low weight.

The inventive processes are described below, as are the other articles, processes, and uses.

A significant feature of the inventive processes is that carbon nanotubes are present in the substrate surface of the substrate to be metallized. This means that either the substrate itself—and therefore also its surface—comprises carbon nanotubes, or else that carbon nanotubes are applied in the form of an adherent polymer coating or of a lacquer to a substrate in which no carbon nanotubes are intrinsically present. The carbon nanotubes located in or on the substrate surface bring about electrical conductivity, this being essential for the subsequent process of metal deposition on the substrate by a chemical and/or electroplating method. By way of example, there can be further electrically conductive components, such as metal powders or carbon black particles, located in or on the substrate surface alongside the carbon nanotubes, in order to increase electrical conductivity, but their presence is not essential to the invention. The carbon nanotubes per se and their preparation are described (components B or B′) at a later stage below.

In preferred embodiments of the inventive processes, therefore, the substrates used in the process of metal deposition by a chemical and/or electroplating method have been produced from a molding composition which comprises carbon nanotubes and which is described in more detail at a later stage below. In other preferred embodiments of the inventive processes, substrates used in the process of metal deposition by a chemical and/or electroplating method are those which have been provided with a dispersion described at a later stage below and comprising carbon nanotubes, and which have then been at least partially dried and/or at least partially hardened.

Molding Compositions Comprising Carbon Nanotubes

In one preferred embodiment, the substrates that can be used in the inventive processes are based on thermoplastic molding compositions comprising, based on the total weight of components A, B, C, and D, which is 100% by weight,

• a from 20 to 99% by weight, preferably from 55 to 95% by weight, particularly preferably from 60 to 92% by weight, of component A,
• b from 1 to 30% by weight, preferably from 5 to 25% by weight, particularly preferably from 8 to 20% by weight, of component B.
• c from 0 to 10% by weight, preferably from 0 to 8% by weight, particularly preferably from 0 to 5% by weight, of component C, and
• d from 0 to 40% by weight, preferably from 0 to 30% by weight, particularly preferably from 0 to 10% by weight, of component D.

The individual components of these molding compositions are described below:

Component A

In principle, any of the thermoplastic polymers is suitable as component A. The thermoplastic polymers are generally those whose tensile strain at break is in the range from 10% to 1000%, preferably in the range from 20 to 700, particularly preferably in the range from 50 to 500. (These, and all of the other, values for tensile strain at break and tensile strength mentioned in this application are determined on test specimens of type 1BA (annex A of the standard mentioned: “small test specimens”) in the ISO 527-2:1996 tensile test.)

Examples of a suitable component A are polyethylene, polypropylene, polyvinyl chloride, polystyrene (impact-modified or non-impact-modified), ABS (acrylonitrile-butadiene-styrene), ASA (acrylonitrile-styrene-acrylate), MABS (transparent ABS, comprising methacrylate units), styrene-butadiene block copolymer (e.g. Styroflex® or Styrolux® from BASF Aktiengesellschaft, K-Resin™ from CPC), polyamides, polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETG), polybutylene terephthalate (PBT), aliphatic-aromatic copolyesters (e.g. Exoflex® from BASF Aktiengesellschaft), polycarbonate (e.g. Makrolon® from Bayer AG), polymethyl methacrylate (PMMA), poly(ether) sulfones, and polyphenylene oxide (PPO).

As component A, preference is given to the use of one or more polymers selected from the group of impact-modified vinylaromatic copolymers, of polyolefins, of aliphatic-aromatic copolyesters, of polycarbonates, of thermoplastic polyurethanes, and of styrene-based thermoplastic elastomers.

Polyamides can be used as likewise preferred component A.

Impact-Modified Vinylaromatic Copolymers:

Preferred impact-modified vinylaromatic copolymers are impact-modified copolymers composed of vinylaromatic monomers and of vinyl cyanides (SAN). The preferred impact-modified SAN used preferably comprises ASA polymers and/or ABS polymers, or else (meth)acrylate-acrylonitrile-butadiene-styrene polymers (“MABS”, transparent ABS), or else blends of SAN, ABS, ASA, and MABS with other thermoplastics, for example with polycarbonate, with polyamide, with polyethylene terephthalate, with polybutylene terephthalate, with PVC, or with polyolefins.

The tensile strain at break values of the ASA and ABS that can be used as components A are generally from 10% to 300%, preferably from 15 to 250%, particularly preferably from 20% to 200%.

ASA polymers are generally impact-modified SAN polymers which comprise elastomeric graft copolymers of vinylaromatic compounds, in particular styrene, and vinyl cyanides, in particular acrylonitrile, on polyalkyl acrylate rubbers in a copolymer matrix composed, in particular, of styrene and/or α-methylstyrene and acrylonitrile.

In one preferred embodiment in which the thermoplastic molding compositions comprise ASA polymers, the elastomeric graft copolymer A^R of component A is composed of

• a1 from 1 to 99% by weight, preferably from 55 to 80% by weight, in particular from 55 to 65% by weight, of a particulate graft base A1 with a glass transition temperature below 0° C.,
• a2 from 1 to 99% by weight, preferably from 20 to 45% by weight, in particular from 35 to 45% by weight, of a graft A2 composed of the following monomers, based on A2,
• a21 from 40 to 100% by weight, preferably from 65 to 85% by weight, of units of styrene, of a substituted styrene, or of a (meth)acrylate, or of a mixture of these, in particular of styrene and/or α-methylstyrene, as component A21, and
• a22 up to 60% by weight, preferably from 15 to 35% by weight, of units of acrylonitrile or methacrylonitrile, in particular of acrylonitrile, as component A22.

The graft A2 here is composed of at least one graft shell.

Component A1 Here is Composed of the Following Monomers

• a11 from 80 to 99.99% by weight, preferably from 95 to 99.9% by weight, of at least one C₁-C₈-alkyl acrylate, preferably n-butyl acrylate and/or ethylhexyl acrylate, as component A 1,
• a12 from 0.01 to 20% by weight, preferably from 0.1 to 5.0% by weight, of at least one polyfunctional crosslinking monomer, preferably diallyl phthalate and/or DCPA, as component A12.

According to one embodiment of the invention, the average particle size of component A^R is from 50 to 1000 nm, with monomodal distribution.

In another embodiment, the particle size distribution of component A^R is bimodal, from 60 to 90% by weight having an average particle size of from 50 to 200 nm, and from 10 to 40% by weight having an average particle size of from 50 to 400 nm, based on the total weight of component A^R.

The average particle size and particle size distribution given are the sizes determined from the cumulative weight distribution. The average particle sizes are in all cases the weight average of the particle sizes. The determination of these is based on the method of W. Scholtan and H. Lange, Kolloid-Z. und Z.-Polymere 250 (1972), pp. 782-796, using an analytical ultracentrifuge. The ultracentrifuge measurement gives the cumulative weight distribution of the particle diameter of a specimen. From this it is possible to deduce what percentage by weight of the particles have a diameter identical to or smaller than a particular size. The average particle diameter, which is also termed the d₅₀ of the cumulative weight distribution, is defined here as that particle diameter at which 50% by weight of the particles have a diameter smaller than that corresponding to the d₅₀. Equally, 50% by weight of the particles then have a larger diameter than the d₅₀. To describe the breadth of the particle size distribution of the rubber particles, d₁₀ and d₉₀ values given by the cumulative weight distribution are utilized alongside the d₅₀ (average particle diameter). The d₁₀ and d₉₀ of the cumulative weight distribution are defined similarly to the d₅₀ with the difference that they are based on, respectively, 10 and 90% by weight of the particles. The quotient

(d₉₀−d₁₀)/d₅₀=Q

is a measure of the breadth of the particle size distribution. Elastomeric graft copolymers A^R preferably have Q values less than 0.5, in particular less than 0.35.

The acrylate rubbers A1 are preferably alkyl acrylate rubbers composed of one or more C₁-C₈-alkyl acrylates, preferably C₄-C₈-alkyl acrylates, preferably with use of at least some butyl, hexyl, octyl or 2-ethylhexyl acrylate, in particular n-butyl and 2-ethylhexyl acrylate. These alkyl acrylate rubbers may comprise, as comonomers, up to 30% by weight of hard-polymer-forming monomers, such as vinyl acetate, (meth)acrylonitrile, styrene, substituted styrene, methyl methacrylate, vinyl ether.

The acrylate rubbers also comprise from 0.01 to 20% by weight, preferably from 0.1 to 5% by weight, of crosslinking, polyfunctional monomers (crosslinking monomers). Examples of these are monomers which comprise two or more double bonds capable of copolymerization, preferably not 1,3-conjugated.

Examples of suitable crosslinking monomers are divinylbenzene, diallyl maleate, diallyl fumarate, diallyl phthalate, diethyl phthalate, triallyl cyanurate, triallyl isocyanurate, tricyclodecenyl acrylate, dihydrodicyclopentadienyl acrylate, triallyl phosphate, allyl acrylate, allyl methacrylate. Dicyclopentadienyl acrylate (DCPA) has proven to be a particularly suitable crosslinking monomer (cf. DE-C 12 60 135).

Component A^R is a graft copolymer. These graft copolymers A^R have an average particle size d₅₀ of from 50 to 1000 nm, preferably from 50 to 800 nm, and particularly preferably from 50 to 600 nm. These particle sizes may be achieved if the graft base A1 used has a particle size of from 50 to 800 nm, preferably from 50 to 500 nm, and particularly preferably from 50 to 250 nm. The graft copolymer A^R generally has one or more stages, i.e. is a polymer composed of a core and one or more shells. The polymer is composed of a first stage (graft core) A1 and of one or—preferably—more stages A2 (grafts) grafted onto this first stage and known as graft stages or graft shells.

Simple grafting or multiple stepwise grafting may be used to apply one or more graft shells to the rubber particles, and each of these graft shells may have a different makeup. In addition to the grafting monomers, polyfunctional crosslinking monomers or monomers comprising reactive groups may also be included in the grafting process (see, for example, EP-A 230 282, DE-B 36 01 419, EP-A 269 861).

In one preferred embodiment, component A^R is composed of a graft copolymer built up in two or more stages, the graft stages generally being prepared from resin-forming monomers and having a glass transition temperature T_g above 30° C., preferably above 50° C. The structure having two or more stages serves, inter alia, to make the rubber particles A^R (partially) compatible with the thermoplastic matrix.

An example of a preparation method for graft copolymers A^R is grafting of at least one of the monomers A2 listed below onto at least one of the graft bases or graft core materials A1 listed above.

In one embodiment of the invention, the graft base A1 is composed of from 15 to 99% by weight of acrylate rubber, from 0.1 to 5% by weight of crosslinker, and from 0 to 49.9% by weight of one of the stated other monomers or rubbers.

Suitable monomers for forming the graft A2 are styrene, α-methylstyrene, (meth)acrylates, acrylonitrile, and methacrylonitrile, in particular acrylonitrile.

In one embodiment of the invention, crosslinked acrylate polymers with a glass transition temperature below 0° C. serve as graft base A1. The crosslinked acrylate polymers are preferably to have a glass transition temperature below −20° C., in particular below −30° C.

In one preferred embodiment, the graft A2 is composed of at least one graft shell, and the outermost graft shell of these has a glass transition temperature of more than 30° C., while a polymer formed from the monomers of the graft A2 would have a glass transition temperature of more than 80° C.

Suitable preparation processes for graft copolymers A^R are emulsion, solution, bulk, or suspension polymerization. The graft copolymers A^R are preferably prepared by free-radical emulsion polymerization in the presence of latices of component A1 at from 20° C. to 90° C., using water-soluble or oil-soluble initiators, such as peroxodisulfate or benzoyl peroxide, or with the aid of redox initiators. Redox initiators are also suitable for polymerization below 20° C.

Suitable emulsion polymerization processes are described in DE-A 28 26 925, 31 49 358, and DE-C 12 60 135.

The graft shells are preferably built up in the emulsion polymerization process described in DE-A 32 27 555, 31 49 357, 31 49 358, 34 14 118. The defined setting of the particle sizes of from 50 to 1000 nm preferably takes place by the processes described in DE-C 12 60 135 and DE-A28 26 925, and Applied Polymer Science, volume 9 (1965), p. 2929. The use of polymers with different particle sizes is known from DE-A 28 26 925 and U.S. Pat. No. 5,196,480, for example.

The process described in DE-C 12 60 135 begins by preparing the graft base A1 by polymerizing in a manner known per se, at from 20 to 100° C., preferably from 50 to 80° C., the acrylate(s) used in one embodiment of the invention and the polyfunctional crosslinking monomer, if appropriate together with the other comonomers, in aqueous emulsion. Use may be made of the usual emulsifiers, such as alkali metal alkyl- or alkylarylsulfonates, alkyl sulfates, fatty alcohol sulfonates, salts of higher fatty acids having from 10 to 30 carbon atoms or resin soaps. It is preferable to use the sodium salts of alkylsulfonates or fatty acids having from 10 to 18 carbon atoms. In one embodiment, the amounts used of the emulsifiers are from 0.5 to 5% by weight, in particular from 1 to 2% by weight, based on the monomers used in preparing the graft base A1. Operations are generally carried out with a ratio of water to monomers of from 2:1 to 0.7:1 by weight. The polymerization initiators used are in particular the commonly used persulfates, such as potassium persulfate. However, it is also possible to use redox systems. The amounts generally used of the initiators are from 0.1 to 1% by weight, based on the monomers used in preparing the graft base A1. Other polymerization auxiliaries which may be used during the polymerization are the usual buffer substances which can set a preferred pH of from 6 to 9, examples being sodium bicarbonate and sodium pyrophosphate, and also from 0 to 3% by weight of a molecular weight regulator, such as mercaptans, terpinols or dimeric α-methylstyrene. The precise polymerization conditions, in particular the nature, feed parameters, and amount of the emulsifier, are determined individually within the ranges given above in such a way that the resultant latex of the crosslinked acrylate polymer has a d₅₀ in the range from about 50 to 800 nm, preferably from 50 to 500 nm, particularly preferably in the range from 80 to 250 nm. The particle size distribution of the latex here is preferably intended to be narrow.

In one embodiment of the invention, to prepare the graft polymer A^R, in a following step, in the presence of the resultant latex of the crosslinked acrylate polymer, a monomer mixture composed of styrene and acrylonitrile is then polymerized, and in one embodiment of the invention here the weight ratio of styrene to acrylonitrile in the monomer mixture should be in the range from 100:0 to 40:60, and preferably in the range from 65:35 to 85:15. This graft copolymerization of styrene and acrylonitrile onto the crosslinked polyacrylate polymer serving as a graft base is again advantageously carried out in aqueous emulsion under the usual conditions described above. The graft copolymerization may usefully take place in the system used for the emulsion polymerization to prepare the graft base A1, where further emulsifier and initiator may be added if necessary. The mixture of styrene and acrylonitrile monomers which is to be grafted on in one embodiment of the invention may be added to the reaction mixture all at once, in portions in more than one step, or preferably continuously during the course of the polymerization. The graft copolymerization of the mixture of styrene and acrylonitrile in the presence of the crosslinking acrylate polymer is carried out in such a way as to obtain in graft copolymer A^R a degree of grafting of from 1 to 99% by weight, preferably from 20 to 45% by weight, in particular from 35 to 45% by weight, based on the total weight of component A^R. Since the grafting yield in the graft copolymerization is not 100%, the amount of the mixture of styrene and acrylonitrile monomers which has to be used in the graft copolymerization is somewhat greater than that which corresponds to the desired degree of grafting. Control of the grafting yield in the graft copolymerization, and therefore of the degree of grafting of the finished graft copolymer A^R, is a topic with which the person skilled in the art is familiar. It may be achieved, for example, via the metering rate of the monomers or via addition of regulators (Chauvel, Daniel, ACS Polymer Preprints 15 (1974), pp. 329 ff.). The emulsion graft copolymerization generally gives approximately 5 to 15% by weight, based on the graft copolymer, of free, ungrafted styrene-acrylonitrile copolymer. The proportion of the graft copolymer A^R in the polymerization product obtained in the graft copolymerization is determined by the method given above. Preparation of the graft copolymers A^R by the emulsion process also gives, besides the technical process advantages stated above, the possibility of reproducible changes in particle sizes, for example by agglomerating the particles at least to some extent to give larger particles. This implies that polymers with different particle sizes may also be present in the graft copolymers A^R. Component A^R composed of graft base and graft shell(s) can in particular be ideally adapted to the respective application, in particular with regard to particle size.

The graft copolymers A^R generally comprise from 1 to 99% by weight, preferably from 55 to 80% by weight, and particularly preferably from 55 to 65% by weight, of graft base A1 and from 1 to 99% by weight, preferably from 20 to 45% by weight, particularly preferably from 35 to 45% by weight, of the graft A2, based in each case on the entire graft copolymer.

ABS polymers are generally understood to be impact-modified SAN polymers in which diene polymers, in particular poly-1,3-butadiene, are present in a copolymer matrix, in particular of styrene and/or α-methylstyrene, and acrylonitrile.

In one preferred embodiment, in which the thermoplastic molding compositions comprise ABS polymers, the elastomeric graft copolymer A^R′, of component A is composed of

• a1′ from 10 to 90% by weight of at least one elastomeric graft base with a glass transition temperature below 0° C., obtainable by polymerizing, based on A1′,
• a11′ from 60 to 100% by weight, preferably from 70 to 100% by weight, of at least one conjugated diene and/or C₁-C₁₀-alkyl acrylate, in particular butadiene, isoprene, n-butyl acrylate and/or 2-ethylhexyl acrylate,
• a12′ from 0 to 30% by weight, preferably from 0 to 25% by weight, of at least one other monoethylenically unsaturated monomer, in particular styrene, α-methyl-styrene, n-butyl acrylate, methyl methacrylate, or a mixture of these, and among the last-named in particular butadiene-styrene copolymers and n-butyl acrylate-styrene copolymers, and
• a13′ from 0 to 10% by weight, preferably from 0 to 6% by weight, of at least one crosslinking monomer, preferably divinylbenzene, diallyl maleate, allyl (meth)acrylate, dihydrodicyclopentadienyl acrylate, divinyl esters of dicarboxylic acids, such as succinic and adipic acid, and diallyl and divinyl ethers of bifunctional alcohols, such as ethylene glycol or butane-1,4-diol,
• a2′ from 10 to 60% by weight, preferably from 15 to 55% by weight, of a graft A2′, composed of, based on A2′,
• a21′ from 50 to 100% by weight, preferably from 55 to 90% by weight, of at least one vinylaromatic monomer, preferably styrene and/or α-methylstyrene,
• a22′ from 5 to 35% by weight, preferably from 10 to 30% by weight, of acrylonitrile and/or methacrylonitrile, preferably acrylonitrile,
• a23′ from 0 to 50% by weight, preferably from 0 to 30% by weight, of at least one other monoethylenically unsaturated monomer, preferably methyl methacrylate and n-butyl acrylate.

In another preferred embodiment in which the thermoplastic molding compositions comprise ABS, component A^R′ is a graft rubber with bimodal particle size distribution, composed of, based on A^R′,

• a1″ from 40 to 90% by weight, preferably from 45 to 85% by weight, of an elastomeric particulate graft base A1″, obtainable by polymerizing, based on A1″,
• a11″ from 70 to 100% by weight, preferably from 75 to 100% by weight, of at least one conjugated diene, in particular butadiene and/or isoprene,
• a12″ from 0 to 30% by weight, preferably from 0 to 25% by weight, of at least one other monoethylenically unsaturated monomer, in particular styrene, α-methyl-styrene, n-butyl acrylate, or a mixture of these,
• a2″ from 10 to 60% by weight, preferably from 15 to 55% by weight, of a graft A2″ composed of, based on A2″,
• a21″ from 65 to 95% by weight, preferably from 70 to 90% by weight, of at least one vinylaromatic monomer, preferably styrene,
• a22″ from 5 to 35% by weight, preferably from 10 to 30% by weight, of acrylonitrile,
• a23″ from 0 to 30% by weight, preferably from 0 to 20% by weight, of at least one other monoethylenically unsaturated monomer, preferably methyl methacrylate and n-butyl acrylate.

In one preferred embodiment, in which the thermoplastic molding compositions comprise ASA polymers as component A, the hard matrix A^M of component A is at least one hard copolymer which comprises units which derive from vinylaromatic monomers, and comprising, based on the total weight of units deriving from vinylaromatic monomers, from 0 to 100% by weight, preferably from 40 to 100% by weight, particularly preferably from 60 to 100% by weight, of units deriving from α-methylstyrene, and comprising from 0 to 100% by weight, preferably from 0 to 60% by weight, particularly preferably from 0 to 40% by weight, of units deriving from styrene, composed of, based on A^M,

• a^M1 from 40 to 100% by weight, preferably from 60 to 85% by weight, of vinylaromatic units, as component A^M 1,
• a^M2 up to 60% by weight, preferably from 15 to 40% by weight, of units of acrylonitrile or of methacrylonitrile, in particular of acrylonitrile, as component A^M2.

In one preferred embodiment, in which the thermoplastic molding compositions comprise ABS polymers as component A, the hard matrix A^M′ of component A is at least one hard copolymer which comprises units which derive from vinylaromatic monomers, and comprising, based on the total weight of units deriving from vinylaromatic monomers, from 0 to 100% by weight, preferably from 40 to 100% by weight, particularly preferably from 60 to 100% by weight, of units deriving from α-methylstyrene, and from 0 to 100% by weight, preferably from 0 to 60% by weight, particularly preferably from 0 to 40% by weight, of units deriving from styrene, composed of, based on A^M′,

• a^M1′ from 50 to 100% by weight, preferably from 55 to 90% by weight, of vinylaromatic monomers,
• a^M2′ from 0 to 50% by weight of acrylonitrile or methacrylonitrile or a mixture of these,
• a^M3′ from 0 to 50% by weight of at least one other monoethylenically unsaturated monomer, such as methyl methacrylate and N-alkyl- or N-arylmaleimides, e.g. N-phenylmaleimide.

In another preferred embodiment, in which the thermoplastic molding compositions comprise ABS as component A, component A^M′ is at least one hard copolymer with a viscosity number VN (determined to DIN 53726 at 25° C. in 0.5% strength by weight solution in dimethylformamide) of from 50 to 120 ml/g, comprising units which derive from vinylaromatic monomers, and comprising, based on the total weight of units deriving from vinylaromatic monomers, from 0 to 100% by weight, preferably from 40 to 100% by weight, particularly preferably from 60 to 100% by weight, of units deriving from α-methylstyrene, and from 0 to 100% by weight, preferably from 0 to 60% by weight, particularly preferably from 0 to 40% by weight, of units deriving from styrene, composed of, based on A^M′,

• a_M1″ from 69 to 81% by weight, preferably from 70 to 78% by weight, of vinylaromatic monomers,
• a_M2″ from 19 to 31% by weight, preferably from 22 to 30% by weight, of acrylonitrile,
• a_M³″ from 0 to 30% by weight, preferably from 0 to 28% by weight, of at least one other monoethylenically unsaturated monomer, such as methyl methacrylate or N-alkyl- or N-arylmaleimides, e.g. N-phenylmaleimide.

In one embodiment the ABS polymers comprise, alongside one another, components A^M′ whose viscosity numbers VN differ by at least five units (ml/g) and/or whose acrylonitrile contents differ by five units (% by weight). Finally, alongside component A^M′ and the other embodiments, there may also be copolymers present of α-methyl)-styrene with maleic anhydride or maleimides, of α-methyl)styrene with maleimides and methyl methacrylate or acrylonitrile, or of α-methyl)styrene with maleimides, methyl methacrylate, and acrylonitrile.

In these ABS polymers, the graft polymers A^R′ are preferably obtained by means of emulsion polymerization. The mixing of the graft polymers A^R′ with components A^M′, and, if appropriate, other additions generally takes place in a mixing apparatus, producing a substantially molten polymer mixture. It is advantageous for the molten polymer mixture to be cooled very rapidly.

In other respects, the preparation process and general embodiments, and particular embodiments, of the abovementioned ABS polymers are described in detail in the German patent application DE-A 19728629, expressly incorporated herein by way of reference.

The ABS polymers mentioned may comprise other conventional auxiliaries and fillers. Examples of these substances are lubricants and mold-release agents, waxes, pigments, dyes, flame retardants, antioxidants, light stabilizers, and antistatic agents.

According to one preferred embodiment of the invention, the viscosity number of the hard matrices A^M and, respectively, A^M′ of component A is from 50 to 90, preferably from 60 to 80.

The hard matrices A^M and A^M′ of component A are preferably amorphous polymers.

According to one embodiment of the invention, mixtures of a copolymer of styrene with acrylonitrile and of a copolymer composed of α-methylstyrene with acrylonitrile are used as hard matrices A^M and, respectively, A^M′ of component A. The acrylonitrile content in these copolymers of the hard matrices is from 0 to 60% by weight, preferably from 15 to 40% by weight, based on the total weight of the hard matrix. The hard matrices A^M and, respectively, A^M′ of component A also include the free, ungrafted (α-methyl)styrene-acrylonitrile copolymers produced during the graft copolymerization reaction for preparing component A^R and, respectively, A^R′. Depending on the conditions selected during the graft copolymerization reaction for preparing the graft copolymers A^R and, respectively, A^R′ it can be possible for a sufficient proportion of hard matrix to have been formed before the graft copolymerization reaction has ended. However, it will generally be necessary for the products obtained during the graft copolymerization reaction to be blended with additional, separately prepared hard matrix.

The additional, separately prepared hard matrices A^M and, respectively, A^M′ of component A may be obtained by the conventional processes. For example, according to one embodiment of the invention the copolymerization reaction of the styrene and/or α-methylstyrene with the acrylonitrile may be carried out in bulk, solution, suspension, or aqueous emulsion. The viscosity number of component A^M and, respectively, A^M′ is preferably from 40 to 100, with preference from 50 to 90, in particular from 60 to 80. The viscosity number here is determined to DIN 53 726, dissolving 0.5 g of material in 100 ml of dimethylformamide.

The mixing of components A^R (and, respectively, A^R′) and A^M(and, respectively, A^M′) may take place in any desired manner by any of the known methods. If, by way of example, these components have been prepared via emulsion polymerization, it is possible to mix the resultant polymer dispersions with one another, then to precipitate the polymers together and work up the polymer mixture. However, these components are preferably blended via rolling or kneading or extrusion of the components together, the components having been isolated, if necessary, in advance from the aqueous dispersion or solution obtained during the polymerization reaction. The graft copolymerization products obtained in aqueous dispersion may also be only partially dewatered and mixed in the form of moist crumb with the hard matrix, whereupon then the complete drying of the graft copolymers takes place during the mixing process.

Styrene-Based Thermoplastic Elastomers:

Preferred styrene-based thermoplastic elastomers (S-TPE) are those whose tensile strain at break is more than 300%, particularly preferably more than 500%, in particular more than 500% to 600%. The S-TPE admixed particularly preferably comprises a linear or star-shaped styrene-butadiene block copolymer having external polystyrene blocks S and, situated between these, styrene-butadiene copolymer blocks having random styrene/butadiene distribution (S/B)_random or having a styrene gradient (S/B)_taper (e.g. Styroflex® or Styrolux® from BASF Aktiengesellschaft, K-Resin™ from CPC).

The total butadiene content is preferably in the range from 15 to 50% by weight, particularly preferably in the range from 25 to 40% by weight, and the total styrene content is correspondingly preferably in the range from 50 to 85% by weight, particularly preferably in the range from 60 to 75% by weight.

The styrene-butadiene block (S/B) is preferably composed of from 30 to 75% by weight of styrene and from 25 to 70% by weight of butadiene. An (S/B) block particularly preferably has a butadiene content of from 35 to 70% by weight and a styrene content of from 30 to 65% by weight.

The content of the polystyrene blocks S is preferably in the range from 5 to 40% by weight, in particular in the range from 25 to 35% by weight, based on the entire block copolymer. The content of the S/B copolymer blocks is preferably in the range from 60 to 95% by weight, in particular in the range from 65 to 75% by weight.

Particular preference is given to linear styrene-butadiene block copolymers of the general structure S-(S/B)-S having, situated between the two S blocks, one or more (S/B)_random blocks having random styrene/butadiene distribution. Block copolymers of this type are obtainable via anionic polymerization in a non-polar solvent with addition of a polar cosolvent or of a potassium salt, as described by way of example in WO 95/35335 or WO 97/40079.

The vinyl content is the relative content of 1,2-linkages of the diene units, based on the entirety of 1,2-, and 1,4-cis and 1,4-trans linkages. The 1,2-vinyl content in the styrene/butadiene copolymer block (S/B) is preferably below 20%, in particular in the range from 10 to 18%, particularly preferably in the range from 12 to 16%.

Polyolefins:

The polyolefins that can be used as components A generally have tensile strain at break values of from 10% to 600%, preferably from 15% to 500%, particularly preferably from 20% to 400%.

Examples of suitable components A are semicrystalline polyolefins, such as homo- or copolymers of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, or 4-methyl-1-pentene, and ethylene copolymers with vinyl acetate, vinyl alcohol, ethyl acrylate, butyl acrylate, or methacrylate. The component A used preferably comprises a high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), ethylene-vinyl acetate copolymer (EVA), or ethylene-acrylic copolymer. A particularly preferred component A is polypropylene.

Polycarbonates:

The polycarbonates that can be used as components A generally have tensile strain at break values of from 20% to 300%, preferably from 30% to 250%, particularly preferably from 40% to 200%.

The molar mass of polycarbonates suitable as component A (weight average M_w, determined by means of gel permeation chromatography in tetrahydrofuran against polystyrene standards) is preferably in the range from 10 000 to 60 000 g/mol. By way of example, they are obtainable by the processes of DE-B-1 300 266 via interfacial polycondensation or according to the process of DE-A-1 495 730 via reaction of diphenyl carbonate with bisphenols. Preferred bisphenol is 2,2-di(4-hydroxy-phenyl)propane, generally—and also hereinafter—termed bisphenol A.

Instead of bisphenol A, it is also possible to use other aromatic dihydroxy compounds, in particular 2,2-di(4-hydroxyphenyl)pentane, 2,6-dihydroxynaphthalene, 4,4′-di-hydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl sulfite, 4,4′-dihydroxydiphenylmethane, 1,1-di(4-hydroxyphenyl)ethane, 4,4-dihydroxydiphenyl, or dihydroxydiphenylcycloalkanes, preferably dihydroxydiphenylcyclohexanes, or dihydroxycyclopentanes, in particular 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, or else a mixture of the abovementioned dihydroxy compounds.

Particularly preferred polycarbonates are those based on bisphenol A or bisphenol A together with up to 80 mol % of the abovementioned aromatic dihydroxy compounds.

Polycarbonates with particularly good suitability as component A are those which comprise units that derive from resorcinol esters or from alkylresorcinol esters, for example those described in WO 00/61664, WO 00/15718, or WO 00/26274. These polycarbonates are marketed by way of example by General Electric Company, the trademark being SollX®.

It is also possible to use copolycarbonates according to U.S. Pat. No. 3,737,409, and copolycarbonates based on bisphenol A and di(3,5-dimethyldihydroxyphenyl) sulfone are of particular interest here, and feature high heat resistance. It is also possible to use mixtures of different polycarbonates.

The average molar masses (weight average M_w, determined by means of gel permeation chromatography in tetrahydrofuran against polystyrene standards) of the polycarbonates are in the range from 10 000 to 64 000 g/mol. They are preferably in the range from 15 000 to 63 000 g/mol, in particular in the range from 15 000 to 60 000 g/mol. This means that the relative solution viscosities of the polycarbonates are in the range from 1.1 to 1.3, measured in 0.5% strength by weight solution in dichloromethane at 25° C., preferably from 1.15 to 1.33. The difference between the relative solution viscosities of the polycarbonates used is preferably not more than 0.05, in particular not more than 0.04.

The form in which the polycarbonates are used may either be that of regrind or else that of pellets.

Thermoplastic Polyurethane:

Any aromatic or aliphatic thermoplastic polyurethane is generally suitable as component A, and amorphous aliphatic thermoplastic polyurethanes which are transparent have preferred suitability. Aliphatic thermoplastic polyurethanes and their preparation are known to the person skilled in the art, for example from EP-B1 567 883 or DE-A 10321081, and are commercially available, for example with trademarks Texin® and Desmopan® from Bayer Aktiengesellschaft.

The Shore hardness D of preferred aliphatic thermoplastic polyurethanes is from 45 to 70, and their tensile strain at break values are from 30% to 800%, preferably from 50% to 600%, particularly preferably from 80% to 500%.

Particularly preferred components A are the styrene-based thermoplastic elastomers.

Component B

The thermoplastic molding compositions comprise carbon nanotubes as component B. Carbon nanotubes and their preparation are known to the person skilled in the art and are described in the literature, for example in US 2005/0186378 A1. Carbon nanotubes can by way of example be synthesized in a reactor which comprises a metal catalyst and a gas comprising carbon (see, for example, U.S. Pat. No. 5,643,502). Carbon nanotubes are marketed, for example by Hyperion Catalysis, or Applied Sciences Inc.

Preferred carbon nanotubes typically have a single- or multiwall tubular structure. Single-wall carbon nanotubes (SWCN) are formed from a single graphitic carbon layer, and multiwall carbon nanotubes (MWCN) are formed from a plurality of such graphitic carbon layers. The graphite layers have a concentric arrangement around the axis of the cylinder. The length-to-diameter ratio of carbon nanotubes is generally at least 5, preferably at least 100, particularly preferably at least 1000. The diameter of the nanotubes is typically in the range from 0.002 to 0.5 μm, preferably in the range from 0.005 to 0.08 μm, particularly preferably in the range from 0.006 to 0.05 μm. The length of the carbon nanotubes is typically from 0.5 to 1000 μm, preferably from 0.8 to 100 μm, particularly preferably from 1 to 10 μm. The carbon nanotubes have a hollow cylindrical core around which the graphite layers have formally been wound. The diameter of this cavity is typically from 0.001 to 0.1 μm, preferably from 0.008 to 0.015 μm. In a typical embodiment of the carbon nanotubes, the wall of the tubes around the cavity is composed by way of example of 8 graphite sublayers. The carbon nanotubes here can take the form of aggregates of up to 1000 μm in diameter, preferably up to 500 μm in diameter, composed of a plurality of nanotubes. The aggregates can take the form of nests, of combed yarn, or of open network structures.

The carbon nanotubes can be added prior to, during, or after the polymerization of the monomers to give the thermoplastic polymer of component A. If the nanotubes are added after the polymerization, they are preferably added via addition to the thermoplastic melt in an extruder or preferably in a kneader. The compounding procedure in the kneader or extruder can in particular comminute the aggregates described above substantially or even entirely and disperse the carbon nanotubes in the thermoplastic matrix.

In one preferred embodiment, the form in which the carbon nanotubes are fed can be that of highly concentrated masterbatches in thermoplastics, which are preferably selected from the group of the thermoplastics used as component A. The concentration of the carbon nanotubes in the masterbatches is usually in the range from 5 to 50% by weight, preferably from 8 to 30% by weight, particularly preferably in the range from 12 to 22% by weight. The preparation of masterbatches is described by way of example in U.S. Pat. No. 5,643,502. Use of masterbatches can in particular improve the commination of the aggregates. The length distributions of the carbon nanotubes in the molding composition or in the molding can be shorter than that of those originally used, by virtue of processing to give the molding composition or to give the molding.

Component C

In principle, any of the dispersing agents described in the prior art and known to the person skilled in the art for use in plastics mixtures is suitable as component C. Preferred dispersing agents are surfactants or surfactant mixtures, such as anionic, cationic, amphoteric or nonionic surfactants. Further preference is given to the oligomeric and polymeric dispersing agents commercially available and known to the person skilled in the art as described in CD Römpp Chemie Lexikon [CD Römpp chemical encyclopedia]—Version 3.0, Stuttgart/N.Y.: Georg Thieme Verlag 2006, keyword “Dispergierhilfsmittel” [dispersing agents].

Examples are polycarboxylic acids, polyamines, salts composed of long-chain polyamines and polycarboxylic acids, amine/amide-functional polyesters and polyacrylates, soy lecithins, polyphosphates, modified caseins. These polymeric dispersing agents can be present in the form of block copolymers, comb polymers, or random copolymers.

Cationic and anionic surfactants are described by way of example in “Encyclopedia of Polymer Science and Technology”, J. Wiley & Sons (1966), Volume 5, pp. 816 to 818, and in “Emulsion Polymerisation and Emulsion Polymers”, editors P. Lovell and M. El-Asser, published by Wiley & Sons (1997), pp. 224-226.

Examples of anionic surfactants are alkali metal salts of organic carboxylic acids having chain lengths of from 8 to 30 carbon atoms, preferably from 12 to 18 carbon atoms. These are generally termed soaps. The salts usually used are the sodium, potassium, or ammonium salts. Other anionic surfactants which may be used are alkyl sulfates and alkyl- or alkylarylsulfonates having from 8 to 30 carbon atoms, preferably from 12 to 18 carbon atoms. Particularly suitable compounds are alkali metal dodecyl sulfates, e.g. sodium dodecyl sulfate or potassium dodecyl sulfate, and alkali metal salts of C₁₂-C₁₆ paraffinsulfonic acids. Other suitable compounds are sodium dodecylbenzenesulfonate and sodium dioctyl sulfosuccinate.

Examples of suitable cationic surfactants are salts of amines or of diamines, quaternary ammonium salts, e.g. hexadecyltrimethylammonium bromide, and also salts of long-chain substituted cyclic amines, such as pyridine, morpholine, piperidine. Use is particularly made of quaternary ammonium salts of trialkylamines, e.g. hexadecyltri-methylammonium bromide. The alkyl radicals here preferably have from 1 to 20 carbon atoms.

Nonionic surfactants may in particular be used as component C. Nonionic surfactants are described by way of example in CD Römpp Chemie Lexikon—Version 1.0, Stuttgart/N.Y.: Georg Thieme Verlag 1995, keyword “Nichtionische Tenside” [Nonionic surfactants].

Examples of suitable nonionic surfactants are polyethylene-oxide- or polypropylene-oxide-based substances, such as Pluronic® or Tetronic® from BASF Aktiengesellschaft. Polyalkylene glycols suitable as nonionic surfactants generally have a molar mass M_n in the range from 1 000 to 15 000 g/mol, preferably from 2 000 to 13 000 g/mol, particularly preferably from 4 000 to 11 000 g/mol. Preferred nonionic surfactants are polyethylene glycols.

The polyalkylene glycols are known per se or may be prepared by processes known per se, for example by anionic polymerization using alkali metal hydroxide catalysts, such as sodium hydroxide or potassium hydroxide, or using alkali metal alkoxide catalysts, such as sodium methoxide, sodium ethoxide, potassium ethoxide or potassium isopropoxide, and with addition of at least one starter molecule which comprises from 2 to 8 reactive hydrogen atoms, preferably from 2 to 6 reactive hydrogen atoms, or by cationic polymerization using Lewis acid catalysts, such as antimony pentachloride, boron fluoride etherate, or bleaching earth, the starting materials being one or more alkylene oxides having from 2 to 4 carbon atoms in the alkylene radical.

Examples of suitable alkylene oxides are tetrahydrofuran, butylene 1,2- or 2,3-oxide, styrene oxide, and preferably ethylene oxide and/or propylene 1,2-oxide. The alkylene oxides may be used individually, alternating one after the other, or as a mixture. Examples of starter molecules which may be used are: water, organic dicarboxylic acids, such as succinic acid, adipic acid, phthalic acid, or terephthalic acid, aliphatic or aromatic, unsubstituted or N-mono-, or N,N- or N,N′-dialkyl-substituted diamines having from 1 to 4 carbon atoms in the alkyl radical, such as unsubstituted or mono- or dialkyl-substituted ethylenediamine, diethylenetriamine, triethylenetetramine, 1,3-propylene-diamine, 1,3- or 1,4-butylenediamine, or 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexamethylene-diamine.

Other starter molecules which may be used are: alkanolamines, e.g. ethanolamine, N-methyl- and N-ethylethanolamine, dialkanolamines, e.g. diethanolamine, and N-methyl- and N-ethyldiethanolamine, and trialkanolamines, e.g. triethanolamine, and ammonia. It is preferable to use polyhydric alcohols, in particular di- or trihydric alcohols or alcohols with functionality higher than three, for example ethanediol, 1,2-propanediol, 1,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sucrose, and sorbitol.

Other suitable components C are esterified polyalkylene glycols, such as the mono-, di-, tri- or polyesters of the polyalkylene glycols mentioned which can be prepared by reacting the terminal OH groups of the polyalkylene glycols mentioned with organic acids, preferably adipic acid or terephthalic acid, in a manner known per se. Polyethylene glycol adipate or polyethylene glycol terephthalate is preferred as component C.

Particularly suitable nonionic surfactants are substances prepared by alkoxylating compounds having active hydrogen atoms, for example adducts of ethylene oxide onto fatty alcohols, oxo alcohols, or alkylphenols. It is preferable to use ethylene oxide or 1,2-propylene oxide for the alkoxylation reaction.

Other preferred nonionic surfactants are alkoxylated or nonalkoxylated sugar esters or sugar ethers.

Sugar ethers are alkyl glycosides obtained by reacting fatty alcohols with sugars, and sugar esters are obtained by reacting sugars with fatty acids. The sugars, fatty alcohols, and fatty acids needed to prepare the substances mentioned are known to the person skilled in the art.

Suitable sugars are described by way of example in Beyer/Walter, Lehrbuch der organischen Chemie [Textbook of organic chemistry], S. Hirzel Verlag Stuttgart, 19th edition, 1981, pp. 392 to 425. Particularly suitable sugars are D-sorbitol and the sorbitans obtained by dehydrating D-sorbitol.

Suitable fatty acids are saturated or singly or multiply unsaturated unbranched or branched carboxylic acids having from 6 to 26 carbon atoms, preferably from 8 to 22 carbon atoms, particularly preferably from 10 to 20 carbon atoms, for example as mentioned in CD Römpp Chemie Lexikon—Version 1.0, Stuttgart/N.Y.: Georg Thieme Verlag 1995, keyword “Fettsäuren” [Fatty acids]. Preferred fatty acids are lauric acid, palmitic acid, stearic acid, and oleic acid.

The carbon skeleton of suitable fatty alcohols is identical with that of the compounds described as suitable fatty acids.

Sugar ethers, sugar esters, and the processes for their preparation are known to the person skilled in the art. Preferred sugar ethers are prepared by known processes, by reacting the sugars mentioned with the fatty alcohols mentioned. Preferred sugar esters are prepared by known processes, by reacting the sugars mentioned with the fatty acids mentioned. Preferred sugar esters are the mono-, di-, and triesters of the sorbitans with fatty acids, in particular sorbitan monolaurate, sorbitan dilaurate, sorbitan trilaurate, sorbitan monooleate, sorbitan dioleate, sorbitan trioleate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan tripalmitate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, and sorbitan sesquioleate, a mixture of sorbitan mono- and dioleates.

Component D

The thermoplastic molding compositions comprise, as component D, fibrous or particulate fillers other than component B, or a mixture of these. These are preferably commercially available products, such as carbon fibers and glass fibers.

Glass fibers that may be used may be composed of E, A, or C glass, and have preferably been treated with a size and with a coupling agent. Their diameter is generally from 6 to 20 μm. It is possible to use either continuous-filament fibers (rovings) or else chopped glass fibers (staple) whose length is from 1 to 10 mm, preferably from 3 to 6 mm.

It is also possible to add fillers or reinforcing materials, such as glass beads, mineral fibers, whiskers, aluminum oxide fibers, mica, powdered quartz, and wollastonite.

The thermoplastic molding compositions may moreover comprise other additions which are typical of, and customary in, plastics mixtures.

By way of example of these additions, mention may be made of: dyes, pigments, colorants, antistatic agents, antioxidants, stabilizers for improving heat resistance, for increasing resistance to light, for raising resistance to hydrolysis and to chemicals, agents to counter decomposition by heat, and in particular the lubricants that are advantageous for production of moldings. These other additions may be metered in at any stage of the production process, but preferably at an early juncture, in order that the stabilizing effects (or other specific effects) of the addition may be utilized at an early stage. Heat stabilizers or oxidation retarders are usually metal halides (chlorides, bromides, iodides) derived from metals of group I of the Periodic Table of the Elements (e.g. Li, Na, K, Cu).

Suitable stabilizers are the conventional hindered phenols, but also vitamin E or analogous-structure compounds. HALS stabilizers (Hindered Amine Light Stabilizers), benzophenones, resorcinols, salicylates, benzotriazoles, such as Tinuvin® RP (the UV absorber 2-(2H-benzotriazol-2-yl)-4-methylphenol from CIBA), and other compounds are also suitable. The amounts of these usually used are up to 2% by weight (based on the entire thermoplastic molding composition mixture).

Suitable lubricants and mold-release agents are stearic acids, stearyl alcohol, stearic esters, and generally higher fatty acids, their derivatives, and corresponding fatty acid mixtures having from 12 to 30 carbon atoms. The amounts of these additions are in the range from 0.05 to 1% by weight.

Silicone oils, oligomeric isobutylene, or similar substances may also be used as additives, and the usual amounts are from 0.05 to 5% by weight. It is also possible to use pigments, dyes, color brighteners, such as ultramarine blue, phthalocyanines, titanium dioxide, cadmium sulfides, derivatives of perylenetetracarboxylic acid.

The amounts usually used of processing aids and stabilizers, such as UV stabilizers, lubricants, and antistatic agents, are from 0.01 to 5% by weight.

Process for Production of Metallizable Substrates

The thermoplastic molding compositions are prepared from components A, B, and, if present, C and D by processes known to the person skilled in the art, for example via mixing of the components in the melt, using apparatuses known to the person skilled in the art at temperatures which as a function of the nature of the polymer A used are usually in the range from 150° C. to 300° C., in particular from 200° C. to 280° C. Each of the components here can be introduced in pure form into the mixing apparatuses. However, it is also possible to begin by premixing individual components, such as A and B or A and C, and then to mix these with further components A, B, and/or C, or with other components, such as D. In one embodiment, a concentrate is first prepared, these being known as additive masterbatches, for example from components B, C, or D in component A, and this is then mixed with the desired amounts of the remaining components. The thermoplastic molding compositions can be pelletized by processes known to the person skilled in the art, for, by way of example, subsequent processing via extrusion, injection molding, calendering, or compression molding to give metallizable moldings (i.e. substrates), such as foils or sheets or composite layered foils or composite layered sheets. However, they can also be processed, in particular extruded or injection molded, directly after the mixing procedure or in a single operation with the mixing procedure (i.e. simultaneous mixing in the melt and preferably extrusion, preferably by means of a screw extruder, or injection molding) to give metallizable moldings, such as foils or sheets.

In one preferred embodiment of the processes by means of extrusion, the screw extruder has been designed as a single-screw extruder with at least one distributively mixing screw element.

In a further preferred embodiment of the processes, the screw extruder has been designed as a twin-screw extruder with at least one distributively mixing screw element.

The processes for extrusion of the metallizable moldings can be carried out by methods described in the prior art and known to the person skilled in the art, e.g. slot extrusion in the form of adaptor coextrusion or die coextrusion, and the use of the apparatuses described in the prior art and known to the person skilled in the art. The processes for injection molding, calendering, or compression molding of the metallizable moldings are likewise known to the person skilled in the art and described in the prior art.

The total thickness of metallizable moldings in the form of foils or sheets is generally from 10 μm to 5 mm, preferably from 10 μm to 3 mm, particularly preferably from 20 μm to 1.5 mm, in particular from 100 μm to 400 μm.

The metallizable moldings can be subjected to further shaping processes conventional in plastics processing technology.

Moldings Obtainable Via Further Shaping Processes:

The metallizable foils or sheets or composite layered sheets or composite layered foils can be used for production of further moldings. Any desired moldings are accessible here, preference being given to sheet-like moldings, in particular large-surface-area moldings. These foils or sheets and composite layered sheets or composite layered foils are particularly preferably used for production of further moldings in which very good toughness values, good adhesion of the individual layers to one another, and good dimensional stability are important, thus by way of example minimizing breakdown via peel of the surfaces. Particularly preferred moldings which are obtainable by further shaping processes have monofoils or composite layered sheets or composite layered foils and a backing layer composed of plastic applied to the back of the material by an injection-molding, foaming, casting, or compression-molding process.

Processes that are known and described by way of example in WO 04/00935 can be used for production of these moldings from the metallizable foils or sheets or from the metallizable composite layered sheets or metallizable composite layered foils (the processes for further processing of composite layered sheets or composite layered foils being described below, but these processes also being capable of use for further processing the foils or sheets). The material can be applied to the back of the composite layered sheets or composite layered foils by an injection-molding, foaming, casting, or compression-molding process, without any further stage of processing. In particular, the use of the composite layered sheets or composite layered foils described permits production even of slightly three-dimensional components without prior thermoforming. The composite layered sheets or composite layered foils may, however, also be subjected to a prior thermoforming process.

By way of example, it is possible to thermoform composite layered sheets or composite layered foils with the three-layered structure composed of backing layer, intermediate layer, and outer layer, or the two-layer structure composed of backing layer and outer layer, to produce relatively complex components. Either positive or negative thermoforming processes can be used here. Appropriate processes are known to the person skilled in the art. The composite layered sheets or composite layered foils here are oriented in the thermoforming process. Since the surface quality and metallizability of the composite layered sheets or composite layered foils does not decrease with orientation at high orientation ratios, for example up to 1:5, there are almost no restrictions relating to the possible orientation in the thermoforming processes. After the thermoforming process, the composite layered sheets or foils can be subjected to still further shaping steps, for example profile cuts.

The further metallizable moldings can be produced, if appropriate after the thermoforming processes described, by applying material to the back of the composite layered sheets or composite layered foils via injection-molding, foaming, casting, or compression-molding processes. These methods are known to the person skilled in the art and are described by way of example in DE-A1 100 55 190 or DE-A1 199 39 111.

The plastics materials applied in these injection-molding, compression-molding, or casting processes preferably comprise thermoplastic molding compositions based on ASA polymers, on ABS polymers, on SAN polymers, on poly(meth)acrylates, on polyether sulfones, on polybutylene terephthalate, on polycarbonates, on polypropylene (PP), or on polyethylene (PE), or else blends composed of ASA polymers or of ABS polymers and of polycarbonates or polybutylene terephthalate, and blends composed of polycarbonates and polybutylene terephthalate, and if PP and/or PE is used here it is clearly possible to provide the substrate layer in advance with an adhesion-promoter layer. Particularly suitable materials are amorphous thermoplastics and their blends. The plastics material preferably used for application to the back of the material by an injection-molding process is ABS polymers or SAN polymers. In another preferred embodiment, thermoset molding compositions known to the person skilled in the art are used for application to the back of the material by a foaming or compression-molding process. In one preferred embodiment, these are glass-fiber-reinforced plastics materials, and suitable variants are in particular described in DE-A1 100 55 190. For application to the back of the material by a foaming process it is preferable to use polyurethane foams, for example those described in DE-A1 199 39 111.

In one preferred production process the metallizable composite layered sheet or composite layered foil is thermoformed and then placed in a back-molding mold, and thermoplastics are applied to the back of the material by an injection-molding, casting, or compression-molding process, or thermoset plastics are applied to the back of the material by a foaming or compression-molding process.

After thermoforming and prior to placement in the back-molding mold, the composite layered sheet or composite layered foil may undergo a profile cut. The profile cut can also be delayed until after removal from the back-molding mold.

Dispersions Comprising Carbon Nanotubes

In another preferred embodiment, the substrates that can be used in the inventive processes for deposition of a metal by a chemical and/or electroplating method are those in which, prior to the step of metallizing by a chemical and/or electroplating method, the substrate is provided with a dispersion comprising carbon nanotubes and the dispersion is at least partially dried and/or at least partially hardened.

Preferred dispersions comprising carbon nanotubes comprise, based on the total weight of components A′, B′, and C′, which is 100% by weight,

• a′ from 0.1 to 99.9% by weight, preferably from 2 to 89.5% by weight, particularly preferably from 4 to 84% by weight, of component A′,
• b′ from 0.1 to 30% by weight, preferably from 0.5 to 20% by weight, particularly preferably from 1 to 10% by weight, of component B′, and
• c′ from 0 to 99.8% by weight, preferably from 10 to 97.5% by weight, particularly preferably from 15 to 95% by weight, of component C′.

The dispersion can comprise, other than components A′ to C′ mentioned, at least one of the following components:

• d′ from 0.1 to 50% by weight, preferably from 0.5 to 40% by weight, particularly preferably from 1 to 20% by weight, based on the total weight of components A′-C′, of a dispersing agent component D′; and also
• e′ from 0 to 50% by weight, preferably from 0.1 to 40% by weight, particularly preferably from 0.5 to 30% by weight, based on the total weight of components A′-C′, of a filler component E different from component B′.

The individual components of the dispersion are described below:

Component A′

The organic binder component A′ is a binder or binder mixture. Possible binders are binders having an anchor group that has pigment affinity, naturally occurring and synthetic polymers and their derivatives, naturally occurring resins and synthetic resins and their derivatives, natural rubber, synthetic rubber, proteins, cellulose derivatives, drying and non-drying oils, and the like. These can—but do not have to be—substances that cure chemically or physically, for example air-curing, radiation-curing, or heat-curing substances.

The binder component A′ is preferably a polymer or polymer mixture.

Polymers preferred as binder are ABS (acrylonitrile-butadiene-styrene); ASA (acrylonitrile-styrene-acrylate); acrylated acrylates; alkyd resins; alkylvinyl acetates; alkylene-vinyl acetate copolymers, in particular methylene-vinyl acetate, ethylene-vinyl acetate, butylene-vinyl acetate; alkylene-vinyl chloride copolymers; amino resins; aldehyde resins and ketone resins; cellulose and cellulose derivatives, in particular hydroxyalkylcellulose, cellulose esters, such as cellulose acetates, cellulose propionates, cellulose butyrates, carboxyalkylcelluloses, cellulose nitrate; epoxy acrylates; epoxy resins; modified epoxy resins, e.g. bifunctional or polyfunctional bisphenol A or bisphenol F resins, epoxy-novolak resins, brominated epoxy resins, cycloaliphatic epoxy resins; aliphatic epoxy resins, glycidic ethers, vinyl ethers, ethylene-acrylic acid copolymers; hydrocarbon resins; MABS (transparent ABS comprising acrylate units present); melamine resins, maleic anhydride copolymers; methacrylates; natural rubber; synthetic rubber; chlorinated rubber; naturally occurring resins; rosins; shellac; phenolic resins; polyesters; polyester resins, such as phenyl ester resins; polysulfones; polyether sulfones; polyamides; polyimides; polyanilines; polypyrroles; polybutylene terephthalate (PBT); polycarbonate (e.g. Makrolon® from Bayer AG); polyester acrylates; polyether acrylates; polyethylene; polyethylene-thiophenes; polyethylene naphthalates; polyethylene terephthalate (PET); polyethylene terephthalate glycol (PETG); polypropylene; polymethyl methacrylate (PMMA); polyphenylene oxide (PPO); polystyrenes (PS), polytetrafluoroethylene (PTFE); polytetrahydrofuran; polyethers (e.g. polyethylene glycol, polypropylene glycol), polyvinyl compounds, in particular polyvinyl chloride (PVC), PVC copolymers, PVdC, polyvinyl acetate, and also copolymers of these, polyvinyl alcohol, if appropriate in partially hydrolyzed form, polyvinyl acetals, polyvinyl acetates, polyvinylpyrrolidone, polyvinyl ethers, polyvinyl acrylates and polyvinyl methacrylates in solution and in the form of a dispersion, and also copolymers of these, polyacrylates and polystyrene copolymers; polystyrene (impact-modified or non-impact-modified); polyurethanes, non-crosslinked or crosslinked with isocyanates; polyurethane acrylates, styrenic-acrylic copolymers; styrene-butadiene block copolymers (e.g. Styroflex® or Styrolux® from BASF AG, K-Resin™ from CPC, Kraton D or Kraton G from Kraton Polymers); proteins, e.g. casein; SIS; triazine resin, bismaleimide-triazine resin (BT), cyanate ester resin (CE), allylated polyphenylene ethers (APPE).

Mixtures of two or more polymers may also form the organic binder component A′.

Polymers preferred as component A′ are acrylates, acrylate resins, cellulose derivatives, methacrylates, methacrylate resins, melamine, and amino resins, polyalkylenes, polyimides, epoxy resins, modified epoxy resins, e.g. bifunctional or polyfunctional bisphenol A or bisphenol F resins, epoxy-novolak resins, brominated epoxy resins, cycloaliphatic epoxy resins; aliphatic epoxy resins, glycidic ethers, vinyl ethers, and phenolic resins, polyurethanes, polyesters, polyvinyl acetals, polyvinyl acetates, polystyrenes, polystyrene copolymers, polystyrene-acrylates, styrene-butadiene block copolymers, alkylene-vinyl acetates, and vinyl chloride copolymers, polyamides, and also copolymers of these.

Component B′

The carbon nanotubes described above as component B can be used as component B′.

In one embodiment of the invention, the carbon nanotubes can be added to the dispersion by first incorporating the carbon nanotubes into the binder component A′; if component A′ is a polymer or a polymer mixture, this incorporation can take place during or after the polymerization of the monomers to give the binder component A′. If the nanotubes are added after polymerization, they are preferably added via addition to the polymer melt in an extruder or preferably in a kneader. The compounding procedure in the kneader or extruder can comminute aggregates or carbon nanotubes substantially or even entirely and disperse the carbon nanotubes in the polymer matrix.

In one preferred embodiment of the pre-incorporation of the carbon nanotubes into the binder component A′, the form in which the carbon nanotubes are metered into the binder component A′ can be that of high-concentration masterbatches in polymers preferably selected from the group of the polymers used as component A′. The concentration of the carbon nanotubes in the masterbatches is usually in the range from 5 to 50% by weight, preferably from 8 to 30% by weight, particularly preferably in the range from 12 to 22% by weight. The preparation of masterbatches is described by way of example in U.S. Pat. No. 5,643,502. Use of masterbatches can in particular improve the commination of the aggregates.

The length distributions of the carbon nanotubes can be shorter than that originally used, as a result of the incorporation into the dispersion or of the pre-incorporation into component A′.

Component C′

The dispersion moreover comprises a solvent component C′. This is composed of a solvent or of a solvent mixture.

Examples of suitable solvents are aliphatic and aromatic hydrocarbons (e.g. n-octane, cyclohexane, toluene, xylene), alcohols (e.g. methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, amyl alcohol), polyhydric alcohols, such as glycerol, ethylene glycol, propylene glycol, neopentyl glycol, alkyl esters (e.g. methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, 3-methylbutanol), alkoxyalcohols (e.g. methoxypropanol, methoxybutanol, ethoxypropanol), alkylbenzenes (e.g. ethylbenzene, isopropylbenzene), butyl glycol, butyl diglycol, alkyl glycol acetates (e.g. butyl glycol acetate, butyl diglycol acetate), diacetone alcohol, diglycol dialkyl ethers, diglycol monoalkyl ethers, dipropylene diglycol dialkyl ethers, dipropylene glycol monoalkyl ethers, diglycol alkyl ether acetates, dipropylene glycol alkyl ether acetates, dioxane, dipropylene glycol and dipropylene glycol ethers, diethylene glycol and diethylene glycol ethers, DBE (dibasic esters), ethers (e.g. diethyl ether, tetrahydrofuran), ethylene chloride, ethylene glycol, ethylene glycol acetate, ethylene glycol dimethyl ether, cresol, lactones (e.g. butyrolactone), ketones (e.g. acetone, 2-butanone, cyclohexanone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), methyl diglycol, methylene chloride, methylene glycol, methylglycol acetate, methylphenol (ortho-, meta-, para-cresol), pyrrolidones (e.g. N-methyl-2-pyrrolidone), propylene glycol, propylene carbonate, carbon tetrachloride, toluene, trimethylolpropane (TMP), aromatic hydrocarbons and mixtures, aliphatic hydrocarbons and mixtures, alcoholic monoterpenes (e.g. terpineol), water, and also mixtures composed of two or more of these solvents.

Preferred solvents are alcohols (e.g. ethanol, 1-propanol, 2-propanol, butanol), alkoxy alcohols (e.g. methoxypropanol, ethoxypropanol, butylglycol, butyldiglycol), butyrolactone, diglycol dialkyl ethers, diglycol monoalkyl ethers, dipropylene glycol dialkyl ethers, dipropylene glycol monoalkyl ethers, esters (e.g. ethyl acetate, butyl acetate, butylglycol acetate, butyldiglycol acetate, diglycol alkyl ether acetates, dipropylene glycol ether acetates, DBE), ethers (e.g. tetrahydrofuran), polyhydric alcohols, such as glycerol, ethylene glycol, propylene glycol, neopentyl glycol, ketones (e.g. acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), hydrocarbons (e.g. cyclohexane, ethylbenzene, toluene, xylene), N-methyl-2-pyrrolidone, water, and also mixtures of these.

Component D′

The dispersion can moreover comprise, as dispersing agent component D′, the dispersing agent described above as component C.

Component E′

The dispersion can moreover comprise, as filler component E′, the fillers described above as component D.

The dispersions can moreover comprise, alongside the components mentioned A′, B′, C′, and, if appropriate, D′ and/or E′, further additions, such as processing aids and stabilizers, e.g. UV stabilizers, lubricants, corrosion inhibitors, and flame retardants.

It is also possible to use further additives, such as agents with thixotropic effect, e.g. silica, silicates, e.g. Aerosils or bentonites, or organic agents with thixotropic effect and thickeners, e.g. polyacrylic acid, polyurethanes, hydrogenated castor oil, dyes, fatty acids, fatty acid amides, plasticizers, wetting agents, antifoams, lubricants, desiccants, crosslinking agents, photoinitiators, complexing agents, waxes, pigments, and conductive polymer particles.

The content of further additions, based on the total weight of the dispersion, is usually from 0.01 to 30% by weight. The content is preferably from 0.1 to 10% by weight.

Preferred processes for preparation of the dispersion comprise the following steps:

• a′) mixing of components A′ to B′ and of at least one portion of component C′, and also, if appropriate, D′, E′, and further components,
• b′) dispersion of the mixture,
• c′) if appropriate, addition of the proportion not used in step a′) of component C′ for adjustment of viscosity for the respective application method.

The dispersion can be prepared via intensive mixing and dispersion using assemblies known to persons skilled in the art. This includes mixing the components in an intensive-dispersion assembly, e.g. kneaders, ball mills, bead mills, dissolvers, three-roll mills, or rotor-stator mixers.

It is possible to mix all of the desired components of the dispersion in a single step of the process. However, it is also possible to premix two or more components, for example components A′ and B′, as described above, and to delay admixture of the remaining components to a subsequent separate step of the process.

One embodiment of the inventive processes for production of a metal layer on at least one portion of the surface of a substrate comprises the following steps:

• a) application of a dispersion comprising carbon nanotubes to the substrate;
• b) at least partial drying and/or at least partial hardening of the layer applied on the substrate; and
• c) deposition of a metal by a chemical and/or electroplating method on the at least partially dried and/or at least partially hardened dispersion layer.

A suitable substrate is provided by electrically non-conductive materials, such as polymers. Suitable polymers are epoxy resins, e.g. bifunctional or polyfunctional, aramid-reinforced or glass fiber-reinforced or paper-reinforced epoxy resins (e.g. FR4), glass fiber-reinforced plastics, liquid-crystal polymers (LCP), polyphenylene sulfides (PPS), polyoxymethylenes (POM), polyaryl ether ketones (PAEK), polyether ether ketones (PEEK), polyamides (PA), polycarbonates (PC), polybutylene terephthalates (PBT), polyethylene terephthalates (PET), polyimides (PI), polyimide resins, cyanate esters, bismaleimide-triazine resins, nylon, vinyl ester resins, polyesters, polyester resins, polyamides, polyanilines, phenolic resins, polypyrroles, polynaphthalene terephthalates, polymethyl methacrylate, polyethylenedioxythiophenes, phenolic-resin-coated aramid paper, polytetrafluoroethylene (PTFE), melamine resins, silicone resins, fluoro resins, dielectrics, APPE, polyetherimides (PEI), polyphenylene oxides (PPO), polypropylenes (PP), polyethylenes (PE), polysulfones (PSU), polyether sulfones (PES), polyarylamides (PAA), polyvinyl chlorides (PVC), polystyrenes (PS), acrylonitrile-butadiene-styrenes (ABS), acrylonitrile-styrene-acrylates (ASA), styrene-acrylonitriles (SAN), and also mixtures (blends) of two or more of the above-mentioned polymers, which may take a very wide variety of forms. The substrates can comprise additives known to the person skilled in the art, e.g. flame retardants.

In principle, it is also possible to use any of the polymers listed under component A′. Other suitable substrates are composite materials, foam-type polymers, Styropor® Styrodur®, polyurethanes (PU), ceramic surfaces, textiles, cardboard, paperboard, paper, polymer-coated paper, wood, mineral materials, silicon, glass, plant tissue, or else animal tissue, or resin-saturated woven fabrics, pressed to give sheets or rolls.

For the purposes of this embodiment of the present invention, an “electrically non-conductive substrate” preferably means that the surface resistance of the substrate is more than 10⁹ ohms/cm.

The dispersion can be applied to the substrate/backing by methods known to the person skilled in the art.

Application to the substrate surface can take place on one or more sides and can extend over one, two, or three dimensions. The substrate can generally have any desired geometry appropriate for the intended purpose.

The dispersion can be applied in structured or non-structured form in step a). It is preferable that the steps of application [step a)], of drying and/or hardening [step b)], and the deposition of a metal [step c)] are carried out in a continuous procedure. This is possible by virtue of the simple conduct of steps a), b), and c). However, a batchwise or semi-continuous process is, of course, possible.

The coating method used can involve the conventional and well-known coating processes (casting, spreading, doctoring, brushing, printing (intaglio print, screenprint, flexographic print, pad print, inkjet, offset, the LaserSonic® process, as described in DE10051850, etc., spraying, dip-coating, rolling, powdering, fluidized bed, or the like). The layer thickness preferably varies from 0.01 to 100 μm, more preferably from 0.1 to 50 μm, particularly preferably from 1 to 25 μm. The layers can be applied in a non-structured or structured manner.

Conventional methods are used for the drying or hardening of the dispersion applied in structured or non-structured form. For example, the dispersion can be hardened by a chemical route, e.g. via a polymerization, polyaddition or polycondensation reaction of the binder, for example via UV radiation, electron beam, microwave radiation, IR radiation, or heat, or by a purely physical route via evaporation of the solvent. It is also possible to combine drying by a physical and chemical route.

The layer obtained after application of the dispersion and at least partial drying and/or at least partial hardening permits subsequent deposition of a metal by a chemical and/or electroplating method on the at least partially dried and/or at least partially hardened dispersion layer.

Metal Deposition on Substrate by an Electroplating Method

The substrates in whose surface carbon nanotubes are present, for example the thermoplastic molding compositions comprising carbon nanotubes or the substrates coated with dispersions comprising carbon nanotubes, have particular suitability for deposition of metal layers by an electroplating method, i.e. for production of metallized substrates, without any need for complicated pretreatment of the substrate surface.

In principle, any of the processes known to the person skilled in the art and described in the literature for deposition of metals by an electroplating method on plastic surfaces is suitable as process for production of the metallized substrates. (see, for example, Harold Ebneth et al., Metallisieren von Kunststoffen: Praktische Erfahrungen mit physikalisch, chemisch und galvanisch metallisierten Hochpolymeren [Metallization of plastics: practical experience with high polymers metallized by physical, chemical, and electroplating methods], Expert Verlag, Renningen-Malmsheim, 1995, ISBN 3-8169-1037-8; Kurt Heymann et al., Kunststoffinetallisierung: Handbuch für Theorie und Praxis [Metallization of plastics: theoretical and practical manual] No. 22 in the series of publications entitled Galvanotechnik und Oberflächenbehandlung [Electroplating technology and surface treatment], Saulgau: Leuze, 1991; Mittal, K. L. (ed.), Metallized Plastics Three Fundamental and Applied Aspects, Third Electrochemical Society Symposium on Metallized Plastics: Proceedings, Phoenix, Ariz., Oct. 13-18, 1991, New York, Plenum Press).

It is preferable that, after the respective final shaping process, the metallizable substrates are arranged as cathode via application of an electrical potential and brought into contact with an acidic, neutral, or basic metal salt solution, whereupon the metal of this metal salt solution is deposited by an electroplating method on the surface comprising the carbon nanotubes in the metallizable substrates. Preferred metals for deposition are chromium, nickel, copper, gold, and silver, in particular copper. It is also possible to deposit a plurality of metal layers in succession by an electroplating method, for example by introducing the metallizable substrates into dip-coating baths with solutions of different metals, in each case with application of external voltage and flow of current.

Although no particular pretreatment of the surface of the metallizable substrates is needed prior to the metallization by a chemical and/or electroplating method, it is possible in principle to carry out surface activation by processes known to the person skilled in the art. Surface activation of the substrate surface can be used to improve adhesion or else to accelerate metal deposition, by roughening the surface in a controlled manner or using a controlled method to release carbon nanotubes on the surface. Release of carbon nanotubes also has the advantage that a smaller proportion is needed in the polymer matrix to achieve metallization.

By way of example, surface activation can take place via mechanical abrasion, in particular via brushing, grinding, or polishing with an abrasive or impact under pressure from a water jet, sandblasting, or blasting with supercritical carbon dioxide (dry ice), or by physical methods, e.g. via heating, laser, UV light, corona or plasma discharge, and/or chemical abrasion, in particular via etching and/or oxidation. Processes for carrying out mechanical abrasion and/or chemical abrasion are known to the person skilled in the art and are described in the prior art.

The abrasive used for polishing can be any of the abrasives known to the person skilled in the art. An example of a suitable abrasive is pumice flour. In order to ablate the uppermost layer of the hardened dispersion when using a water jet under pressure, the water jet preferably comprises small solid grains, such as pumice flour (Al₂O₃) whose average grain size distribution is from 40 to 120 μm, preferably from 60 to 80 μm, or else powdered quartz (SiO₂) whose grain size is >3 μm.

Surface activation can also take place via stretching (also often termed drawing or extending) of the metallizable substrate, in particular by a factor of from 1.1 to 10, preferably from 1.2 to 5, particularly preferably from 1.3 to 3. The embodiments mentioned of mechanical and/or chemical abrasion and of stretching can, of course, also be applied in combination with one another for surface activation.

The stretching can take place in one or more directions. In the case of extruded profiles, strands, or tubes, stretching preferably takes place in one direction, and in the case of sheet-like plastics articles it is preferable that multidirectional, in particular bidirectional, stretching takes place, for example in the blow-molding or thermoforming process on foils or sheets. In the case of multidirectional stretching, it is essential that the stretching factor mentioned is achieved in at least one direction of stretching. Processes that can be used for stretching are in principle any of the stretching processes described in the literature and known to the person skilled in the art. Examples of preferred stretching processes for foils are blow-molding processes.

In the case of chemical abrasion, it is preferable to use a chemical or mixture of chemicals appropriate for the polymer of the substrate. In the case of chemical abrasion, the polymer can, for example, be at least partially dissolved away at the surface by a solvent, or the chemical structure of the matrix material can be at least to some extent disrupted by means of suitable reagents, thus releasing the carbon nanotubes. Reagents which swell the matrix material are also suitable for releasing the carbon nanotubes. The swelling produces cavities in which the metal ions to be deposited can penetrate from the electrolyte solution, thus permitting metallization of a greater number of carbon nanotubes. The greater number of released carbon nanotubes raises the rate of the metallizing process.

If the matrix material is, for example, an epoxy resin, a modified epoxy resin, an epoxy-novolak, a polyacrylate, ABS, a styrene-butadiene copolymer, or a polyether, release of the carbon nanotubes is preferably achieved by an oxidant. The oxidant breaks bonds of the matrix material, thus permitting break-away of the binder with resultant release of the particles. Examples of suitable oxidants are manganates, e.g. potassium permanganate, potassium manganate, sodium permanganate, sodium manganate, hydrogen peroxide, oxygen, oxygen in the presence of catalysts, e.g. salts of manganese, of molybdenum, of bismuth, of tungsten, and of cobalt, ozone, vanadium pentoxide, selenium dioxide, ammonium polysulfide solution, sulfur in the presence of ammonia or of amines, manganese dioxide, potassium ferrate, dichromate/sulfuric acid, chromic acid in sulfuric acid or in acetic acid or in acetic anhydride, nitric acid, hydroiodic acid, hydrobromic acid, pyridinium dichromate, chromic acid-pyridine complex, chromic anhydride, chromium(VI) oxide, periodic acid, lead tetraacetate, quinone, methylquinone, anthraquinone, bromine, chlorine, fluorine, ferric salt solutions, disulfate solutions, sodium percarbonate, salts of oxohalic acids, e.g. chlorates or bromates or iodates, salts of perhalo acids, e.g. sodium periodate or sodium perchlorate, sodium perborate, dichromates, e.g. sodium dichromate, salts of persulfuric acid, such as potassium peroxodisulfate, potassium peroxomonosulfate, pyridinium chlorochromate, salts of hypohalic acids, e.g. sodium hypochloride, dimethyl sulfoxide in the presence of electrophilic reagents, tert-butyl hydroperoxide, 3-chloroperbenzoic acid, 2,2-dimethylpropanal, Des-Martin-periodinane, oxalyl chloride, urea-hydrogen peroxide adduct, urea peroxide, 2-iodoxybenzoic acid, potassium peroxomonosulfate, m-chloroperbenzoic acid, N-methylmorpholine N-oxide, 2-methylprop-2-yl hydroperoxide, peracetic acid, pivaldehyde, osmium tetraoxide, oxones, ruthenium(III) salts and ruthenium(IV) salts, oxygen in the presence 2,2,6,6-tetramethylpiperidinyl N-oxide, triacetoxyperiodinane, trifluoroperacetic acid, trimethylacetaldehyde, ammonium nitrate. The temperature can optionally be increased during the process in order to improve the release process.

Preference is given to manganates, such as potassium permanganate, potassium manganate, sodium permanganate; sodium manganate, hydrogen peroxide, N-methyl-morpholine N-oxide, percarbonates, e.g. sodium percarbonate or potassium percarbonate, perborates, e.g. sodium perborate or potassium perborate; persulfates, such as sodium persulfate or potassium persulfate; the peroxodi- and -monosulfates of sodium, of potassium, and of ammonium, sodium hypochloride, urea-hydrogen peroxide adducts, salts of oxohalic acids, such as chlorates or bromates or iodates, salts of perhalic acids, such as sodium periodate or sodium perchlorate, tetrabutylammonium peroxydisulfate, quinones, ferric salt solutions, vanadium pentoxide, pyridinium dichromate, hydrochloric acid, bromine, chlorine, dichromates.

Particular preference is given to potassium permanganate, potassium manganate, sodium permanganate, sodium manganate, hydrogen peroxide and its adducts, perborates, percarbonates, persulfates, peroxodisulfates, sodium hypochloride, and perchlorates.

For release of the carbon nanotubes in a matrix material which comprises, for example, ester structures, e.g. polyester resins, polyester acrylates, polyether acrylates, polyester urethanes, it is preferable to use, for example, acidic or alkaline chemicals and/or mixtures of chemicals. Preferred acidic chemicals and/or mixtures of chemicals are, for example, concentrated or dilute acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid. Organic acids can also be suitable as a function of the matrix material, examples being formic acid or acetic acid. Suitable alkaline chemicals and/or mixtures of chemicals are, for example, bases, such as sodium hydroxide solution, potassium hydroxide solution, ammonium hydroxide, or carbonates, such as sodium carbonate or potassium carbonate. The temperature can optionally be increased during the process in order to improve the release process.

Solvents can also be used for release of the carbon nanotubes in the matrix material. The solvent has to be appropriately matched to the matrix material, since the matrix material must undergo dissolution in the solvent or solvation by the solvent. If a solvent in which the matrix material is soluble is used, the base layer is brought into contact with the solvent for only a short time, in order that the upper layer of the matrix material is solvated and thus separated. In principle, any of the abovementioned solvents can be used. Preferred solvents are xylene, toluene, halogenated hydrocarbons, acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diethylene glycol monobutyl ether. To improve solvent behavior, the temperature can optionally be increased during the dissolution procedure.

The thicknesses of the one or more metal layers deposited by a chemical and/or electroplating method are within the conventional range known to the person skilled in the art and are not significant for the invention.

Particularly preferred metallized substrates for use as electrically conducting components, in particular printed circuit boards, have at least one metal layer deposited by a chemical and/or electroplating method, in particular a copper layer, silver layer, or gold layer.

Particularly preferred metallized substrates for use in the decorative sector have a copper layer deposited by a chemical and/or electroplating method, and a nickel layer thereupon deposited by a chemical and/or electroplating method, and a chromium layer, silver layer, or gold layer deposited thereupon.

The metallized substrates, if appropriate after production of conductor track structures by the processes described in the literature and known to the person skilled in the art, are suitable as electrically conducting components, in particular printed circuit boards, RFID antennas, transponder antennas, or other antenna structures, switches, sensors, and MIDs, EMI shielding materials (i.e. shielding to avoid electromagnetic interference), such as absorbers, attenuators, or reflectors for electromagnetic radiation, or as gas barriers or decorative parts, in particular decorative parts in the motor vehicle sector, sanitary sector, toy sector, household sector, and office sector.

Examples of these applications are: computer cases, cases for electronic components, military and non-military shielding, devices, shaver fittings and washstand fittings, shower heads, shower rails, shower holders, metallized door handles and door knobs, toilet-paper-roll holders, bathtub grips, metallized decorative strips on furniture and on mirrors, and frames for shower partitions.

Mention may also be made of: metallized plastics surfaces in the automotive sector, e.g. decorative strips, exterior mirrors, radiator grilles, front end metallization, aerofoil surfaces, exterior bodywork parts, door sills, replacement tread plate, decorative wheel covers.

Parts that can be produced from plastic are particularly those which hitherto have been produced partially or entirely from metals. Examples that may be mentioned here are: tools, such as pliers, screwdrivers, drills, drill chucks, saw blades, ring wrenches, and open-jaw wrenches.

The metallized substrates—insofar as they comprise magnetizable metals—are also used in the sectors of magnetizable functional parts, e.g. magnetic panels, magnetic games, magnetic surfaces in, for example, refrigerator doors. They are also applied in sectors where good thermal conductivity is advantageous, for example in foils for seat-heating systems, floor covering-heating systems, insulation materials.

The inventive processes permit improved application of a metal layer on a substrate via deposition of a metal from a metal salt solution by a chemical and/or electroplating method. In particular, the inventive processes can deposit, on a substrate, metal layers with good adhesion to the substrate within comparatively short electroplating times at low cost and with good quality. The resultant metallized substrates have comparatively low weight.

Examples are used below for further illustration of the invention.

EXAMPLES

Experimental part 1

Substrates Composed of a Molding Composition Comprising Carbon Nanotubes

The following were used as component A:

• A-i Styroflex® 2G66, an S-TPE from BASF Aktiengesellschaft.
• A-ii PP4821 polypropylene from Borealis, melt flow index 2.4 g/10 min (determined to ISO 1133 at 230° C. and 2.16 kg).

The following were used as component B:

• B-i Baytubes® C150P, multiwall carbon nanotubes from Bayer Material Science AG with carbon content >95% by weight, with average particle diameter of from 13 to 16 nm and with length of from 1 to 10 μm.

The following components were used for non-inventive comparative experiments:

• Comp-i: Vulcan® XC 72R, conductive carbon black from Cabot Corp.

Production of Metallizable Substrates:

Taking the quantitative proportions of component A mentioned in Table 1, in an IKA Duplex kneader at temperatures of from 120° C. to 150° C., the quantitative proportions likewise mentioned in Table 1 of the further components were added in portions and mixed (data in % by weight, based in each case on the total weight of all of the components). The molding compositions obtained after kneading for about 30 minutes were injection-molded to give flat test specimens of edge length 50×50 mm.

Surface Activation:

The following surface activation was also carried out on the appropriately indicated test specimens in Table 1:

The test specimens were immersed for a period of 2 min in an aqueous solution whose temperature was 80° C. comprising 6% by weight of KMnO₄ and 4.5% by weight of NaOH (based in each case on the total weight of the aqueous solution). The test specimens were then rinsed with a stream of running water for 30 s. Finally, the test specimens were immersed for a period of 1 min in an aqueous solution comprising 2% by weight of H₂O₂ and 10% by weight of H₂SO₄ (based in each case on the total weight of the aqueous solution).

Metallization:

The test specimens were metallized for a period of 30 min via immersion and application of an electrical potential of 1 V into a commercially available acidic Cupracid® HS copper sulfate bath (comprising 21% by weight of CuSO₄, 5.5% by weight of H₂SO₄, 0.2% by weight of brightener, 0.5% by weight of HS leveler, and 0.02% by weight of NaCl, based in each case on the total weight of the solution, in aqueous solution) from Atotech. A test specimen was regarded as metallizable if a visually homogeneous copper layer had deposited on the entire test specimen after the minutes of electroplating.

Table 1 gives the metallizability of the test specimens.

TABLE 1
Constitution of molding compositions
[% by weight, based on total weight	Example*
of molding compositions]	1	2	3	Comp-1	Comp-2
A-i	80	92	—	80	80
A-ii	—	—	90	—	—
B-i	20	8	10	—	10
Comp-i	—	—	—	20	10
Surface activation	no	yes	yes	no	no
Metallizability**	yes	yes	yes	no	no
*examples indicated by “comp” are comparative examples,
**a test specimen was classified with “yes” for metallizability if a visually homogeneous copper layer had deposited on the entire test specimen after the 30 minutes of electroplating mentioned in the description.

Experimental part 2

Coating of a Substrate with a Dispersion Comprising Carbon Nanotubes

The following were used as component A′:

• A′-i Styroflex® 2G66, an S-TPE from BASF Aktiengesellschaft.

The following were used as component B′:

• B′-i Baytubes® C150P, multiwall carbon nanotubes from Bayer Material Science AG with carbon content >95% by weight, with average particle diameter of from 13 to 16 nm and with length of from 1 to 10 μm.

The following were used as component C′:

• C′-i n-butyl acetate.

The following were used as component E′:

• E′-i: Vulcan® XC 72R, a conductive carbon black from Cabot Corp.

Preparation of Dispersions:

Taking the quantitative proportions mentioned in Table 2 of component A′, the quantitative proportions of component B′ likewise mentioned in Table 2 were added in portions and mixed in an IKA Duplex kneader at temperatures of 120° C. (data in % by weight, based in each case on the total weight of all of the components).

The resultant mixtures were mixed in a Skandex DAS 200 mixer for a period of 1 h in the presence of glass particles with the quantitative proportions mentioned in Table 2 of component C′ and, if appropriate, of further components (data in % by weight, based in each case on the total weight of all of the components). The glass particles were then removed.

Coating of Substrate:

The resultant dispersions were further processed by two alternative methods (indicated in Table 2):

• α) the dispersions were applied to a foil composed of polyethylene terephthalate as substrate. Ten minutes of drying of the dispersion at 80° C. followed, with formation of a layer of thickness about 25 μm on the substrate; or
• β) the dispersions were printed by means of a Saueressig CP90/200 gravure color proofer in the form of an RFID antenna onto a foil composed of polyethylene terephthalate as substrate, and then dried to form tracks whose layer thickness was about 3 μm.

Surface Activation:

In the case of coated substrates appropriately indicated in Table 2, the following surface activation was also carried out:

The coated substrates were immersed for a period of 2 min in an aqueous solution whose temperature was 80° C. comprising 6% by weight of KMnO₄ and 4.5% by weight of NaOH (based in each case on the total weight of the aqueous solution). The coated substrates were then rinsed with a stream of running water for 30 s. Finally, the coated substrates were immersed for a period of 1 min in an aqueous solution comprising 2% by weight of H₂O₂ and 10% by weight of H₂SO₄ (based in each case on the total weight of the aqueous solution).

Metallization:

The coated substrates were metallized for a period of 30 min via immersion and application of an electrical potential of 1 V into a commercially available acidic Cupracid® HS copper sulfate bath (comprising 21% by weight of CuSO₄, 5.5% by weight of H₂SO₄, 0.2% by weight of brightener, 0.5% by weight of HS leveler, and 0.02% by weight of NaCl, based in each case on the total weight of the solution, in aqueous solution) from Atotech. A coated substrate was regarded as metallizable if a visually homogeneous copper layer had deposited on the entire substrate after the 30 minutes of electroplating.

Table 2 gives the metallizability of the coated substrates.

	TABLE 2
	Example*	1	2
	Constitution of dispersion [% by weight,
	based on total weight of dispersion]
	A′-i	22	12.2
	B′-i	3	1.7
	C′-i	75	83.3
	E′-i	—	2.8
	Method of further processing	α	β
	Surface activation	yes	yes
	Metallizability*	yes	yes
	*a coated substrate was classified with “yes” for metallizability if a visually homogeneous copper layer had deposited on the entire substrate after the 30 minutes of electroplating mentioned in the description.

Claims

1. A process for application of a metal layer on a substrate via deposition of a metal from a metal salt solution, which comprises the presence of carbon nanotubes in the substrate surface.

2. The process according to claim 1, wherein the carbon nanotubes used comprise single- or multiwall carbon nanotubes whose length is in the range from 0.5 to 1000 μm and whose diameter is in the range from 0.002 to 0.5 μm.

3. The process according to claim 1, wherein the substrate comprises a thermoplastic molding composition, where the thermoplastic molding composition comprises, based on the total weight of components A, B, C, and D, which is 100% by weight,

a from 20 to 99% by weight of a thermoplastic polymer, as component A,

b from 1 to 30% by weight of carbon nanotubes, as component B,

c from 0 to 10% by weight of a dispersing agent, as component C, and

d from 0 to 40% by weight of fibrous or particulate fillers, or a mixture of these, as component D.

4. The process according to claim 3, wherein the component A used comprises one or more polymers selected from the group of impact-modified vinylaromatic copolymers, polyolefins, polycarbonates, thermoplastic polyurethanes, and styrene-based thermoplastic elastomers.

5. The process according to claim 1, wherein the substrate is provided with a dispersion, and the dispersion is at least partially dried and/or at least partially hardened and, after the at least partial drying and/or at least partial hardening of the dispersion, deposition of the metal takes place by a chemical and/or electroplating method, where the dispersion comprises a′ from 0.1 to 99.9% by weight, based on the total weight of components A′, B′, and C′, of an organic binder component A′;

b′ from 0.1 to 30% by weight, based on the total weight of components A′, B′, and C′, of carbon nanotubes, as component B′;

c′ from 0 to 99.8% by weight, based on the total weight of components A′, B′, and C′, of a solvent component C′.

6. The process according to claim 5, wherein the dispersion moreover comprises at least one of the following components:

d′ from 0.1 to 50% by weight, based on the total weight of components A′, B′, and C′, of a dispersing agent component D′; and also

e′ from 0.1 to 50% by weight, based on the total weight of components A′, B′, and C′, of a filler component E′.

7. The process according to claim 5, wherein the binder component A′ is composed of a polymer or polymer mixture.

8. The process according to claim 5, wherein the dispersion is applied in structured or non-structured form to the substrate.

9. The process according to claim 1, wherein the substrate surface in which carbon nanotubes are present is activated prior to deposition of a metal by a chemical and/or electroplating method.

10. (canceled)

11. A substrate surface at least partially having an electrically conductive metal layer obtainable from the process according to claim 1.

12. The substrate surface according to claim 11 wherein the electrically conductive metal layer is provided for conducting electrical current or heat, or as a decorative metal surface, or for shielding from electromagnetic radiation, or else for magnetizing.

13. A printed circuit board, RFID antenna, transponder antenna or other antenna structure, seat-heating system, ribbon cable, foil conductor, contactless chip card, conductor tracks in solar cells, or in LCD display screens or in plasma display screens comprising the substrate surface according to claim 12.

14. The process according to claim 2, wherein the substrate comprises a thermoplastic molding composition, where the thermoplastic molding composition comprises, based on the total weight of components A, B, C, and D, which is 100% by weight,

a from 20 to 99% by weight of a thermoplastic polymer, as component A,

b from 1 to 30% by weight of carbon nanotubes, as component B,

c from 0 to 10% by weight of a dispersing agent, as component C, and

d from 0 to 40% by weight of fibrous or particulate fillers, or a mixture of these, as component D.

15. The process according to claim 2, wherein the substrate is provided with a dispersion, and the dispersion is at least partially dried and/or at least partially hardened and, after the at least partial drying and/or at least partial hardening of the dispersion, deposition of the metal takes place by a chemical and/or electroplating method, where the dispersion comprises

a′ from 0.1 to 99.9% by weight, based on the total weight of components A′, B′, and C′, of an organic binder component A′;

b′ from 0.1 to 30% by weight, based on the total weight of components A′, B′, and C′, of carbon nanotubes, as component B′;

c′ from 0 to 99.8% by weight, based on the total weight of components A′, B′, and C′, of a solvent component C′.

16. The process according to claim 6, wherein the binder component A′ is composed of a polymer or polymer mixture.

17. The process according to claim 6, wherein the dispersion is applied in structured or non-structured form to the substrate.

18. The process according to claim 7, wherein the dispersion is applied in structured or non-structured form to the substrate.

19. The process according to claim 2, wherein the substrate surface in which carbon nanotubes are present is activated prior to deposition of a metal by a chemical and/or electroplating method.

20. The process according to claim 3, wherein the substrate surface in which carbon nanotubes are present is activated prior to deposition of a metal by a chemical and/or electroplating method.

21. The process according to claim 4, wherein the substrate surface in which carbon nanotubes are present is activated prior to deposition of a metal by a chemical and/or electroplating method.