Abstract: A golf ball comprising a core and a cover layer wherein the cover is formed of a polyurethane composition comprising a saturated prepolymer comprising an initiated polycaprolactone and a saturated diisocyanate, and a curing agent.

Abstract: A polyurethane/polyurethane urea resin obtained by reacting an isocyanate group-terminated polyurethane prepolymer (A) obtained by reaction of high molecular weight active hydrogen compound and a polyisocyanate compound, with a chain extender (B), in a solvent and thereafter by removing the solvent, wherein the isocyanate group-terminated polyurethane prepolymer (A) is an isocyanate group-terminated polyurethane prepolymer obtained by reacting the following polyol (1) with a polyisocyanate compound in the presence of an excess amount of an isocyanate group, followed by reacting the following polyol (2) with the reaction product of polyol (1) in the presence of an excess amount of an isocyanate group; Polyol (1): a polyoxyalkylene polyol having a hydroxyl group value of at most 70, a total unsaturation degree of at most 0.

Abstract: The invention relates to coating compositions containing: a) urethane (meth)acrylates that contain (meth)acryloyl groups and free isocyanate groups, b) urethane (meth)acrylates that contain (meth)acryloyl groups and free hydroxyl groups, c) the UV initiators that initiate radical polymerization and d) optionally, one or more compounds that react with isocyanates.

Abstract: A radiation-curable coating composition for an optical fiber comprising a reactive functionality-terminated urethane oligomer, wherein said oligomer comprises the reaction product of (i) a semi-crystalline polyol, and (ii) a non-crystalline polyol in the mole ratio of semi-crystalline polyol to non-crystalline polyol of at least about 1:1, (iii) at least one isocyanate, and (iv) an endcapping compound capable of supplying the functionality terminus.

Abstract: Compact and preferably cellular polyurethane elastomers based on polyisocyanate mixtures containing 3,3′-dimethylbiphenyl 4,4′-diisocyanate are produced by reacting a) relatively high molecular weight polyhydroxyl compounds and, if desired, b) low molecular weight hydroxyl-containing chain extenders and/or crosslinkers with c) 3,3′-dimethylbiphenyl 4,4′-diisocyanate and at least one additional aromatic diisocyanate selected from the group consisting of tolylene diisocyanate, diphenylmethane diisocyanate, 1,2-diphenylethane diisocyanate and phenylene diisocyanate, and/or at least one aliphatic diisocyanate having from 4 to 12 carbon atoms and/or at least one cycloaliphatic diisocyanate having from 6 to 18 carbon atoms, where the formative components (a), (c) and, if used, (b) are advantageously reacted by the prepolymer method, in the presence or absence of d) catalysts, e) blowing agents and f) additives.

Abstract: The present invention relates to a process for the preparation of polyether polyols by catalytic reaction of H-functional initiators with lower alkylene oxides, wherein the catalysts used are multimetal cyanide compounds and the H-functional initiators used are butane-1,4-diol, &agr;-hydroxy-&ohgr;-hydroxypoly(oxybutane-1,4-diyl), pentane-1,5-diol, decane-1,10-diol or mixtures of at least two of these compounds.

Abstract: A polyisocyanate-based elastomer having a ratio of the storage modulus (E′) at 20° C. and the storage modulus (E′) at 120° C. of between 0.75 and 1.5, a tan &dgr; at 100° C. of less than 0.1 and a maximum value of the tan &dgr; of more than 0.8, the tan &dgr; being the ratio of the loss modulus (E″) and the storage modulus (E′).

Abstract: The invention relates to new high-functional polyaddition compounds which contain free isocyanate groups with an average isocyanate functionality of 2.1 to 8.0, a concentration of uretdione of 10 to 18 wt. %, a concentration of urethane of 10 to 20 wt. % and a concentration of ester groups —CO—O and/or carbonate groups —O—CO—O of 1 to 17 wt. %, a process for the preparation thereof and their use as starting components for the preparation of polyurethane plastics, in particular as cross-linking agents for heat-curable powder coatings.

Abstract: A two component chemically thermoset composite resin matrix for use in composite manufacturing processes includes a solvent free polyisocyanate component and a solvent free polyol component. The solvent free polyisocyanate component is either an aromatic polyisocyanate, an aliphatic polyiscyanate or a blend of both. The solvent free polyol component is either a polyether polyol, a polyester polyol or a blend of both. The polyisocyanate component and the polyol component are in relative proportions in accordance with an OH/NCO equivalent ratio of 1:1 to 1:2. The components form a relatively low cost polyurethane composite resin having a useful range of physical properties, without the emission of volatile organic compounds during curing.

Abstract: The present invention relates to polyisocyanate mixtures prepared from aliphatic and/or cycloaliphatic diisocyanates and having a) an average isocyanate functionality of at least 2.0, b) a content of isocyanate groups (calculated as NCO; molecular weight=42) of 4.0 to 28.0 wt. % and c) a content of alkoxy groups having up to 36 carbon atoms of 2.0 to 37.5 wt. %, wherein the alkoxy groups are constituents of allophanate groups or optionally urethane groups, provided that >50 mol % of the alkoxy groups are a constituent of allophanate groups that are connected to at least two polyisocyanate molecules which are each prepared from at least two diisocyanates. The present invention also relates to a process for preparing these polyisocyanate mixtures and to coating compositions, which are highly diluted or dilutable with non-polar solvents and contain these polyisocyanate mixtures and lacquer binders or binder components optionally containing isocyanate-reactive groups.

Abstract: The present invention provides, inter alia, novel fluorinated polyurethane elastomers (e.g., fluorinated thermoset polyurethane elastomers and fluorinated thermoplastic elastomers) prepared from polyether prepolymers formed from mono-substituted fluorinated oxetane monomers (FOX monomers). In addition, the present invention provides methods of making such fluorinated polyurethane elastomers.

Abstract: A method for producing an isocyanate group-blocked liquid urethane prepolymer which comprises: reacting a lactone-modified diol (3) with a polyfunctional isocyanate (4) to form an isocyanate group-having urethane prepolymer (5), wherein said lactone-modified diol (3) is obtainable by ring-opening addition polymerization of a lactone monomer (2) with a diol (1) selected from the group consisting of a polyalkylene ether diol, a polyester diol and a polycarbonate diol; and then reacting said urethane prepolymer with a blocking agent (6).

Abstract: The invention relates to liquid stable MDI prepolymers and curative systems which are suitable for room temperature casting and which yield high performance low-shrinkage urethane elastomers upon room-temperature curing, the prepolymer and curative components, the elastomers themselves, and separately packaged prepolymer component and its complementary curative component provided as a single unit or kit.

Abstract: A two component polyurethane clear coat for use with golf balls includes a polyol component and a polyisocyanate component. The polyol component includes a polyester polyol resin containing a neopentyl glycol resin. A mixture of silane and aziridine is also preferably included in the polyol component. The polyisocynanate component includes a mixture of an isocyanate trimer of hexamethylene diisocyanate and a biuret of hexamethylene diisocyanate. The polyol and polyisocyanate components preferably include two solvents forming a blend selected from the group of ethyl acetate, butyl acetate, propyleneglycolmonomethylether acetate, toluene and xylene. The coating may be applied directly to golf ball covers with a variety of chemistries without the need of a primer or basecoat. The clear coat provides superior adhesion and abrasion resistance in addition to improving the drying and curing characteristics.

Abstract: A process for making polyether polyols employing a double metal cyanide (DMC) catalyst with specific low molecular weight polyether polyols as starters in combination with specific reaction conditions and impurity levels.

Abstract: The invention relates to a coating composition comprising at least one OH-functional binder component and at least one component compound, functioning as a crosslinking agent, which has NCO groups blocked with a pyrazole compound.

Abstract: The present invention relates to new polyamide oligomers. These oligomers can be conjugated to lipids, nucleic acids, peptides, proteins, etc. The oligomer-lipid conjugates can be used to form liposomes, virusomes, micelles, etc., optionally containing drugs or biological agents. The polyamide oligomers are heterobifunctional allowing the attachment of other suitable ligand compounds (e.g., a targeting moiety). In addition, methods of use for the liposomes, virusomes, micelles, etc., are provided.

Abstract: A method of coating a game ball with a rapidly curing polyurethane coating system is described herein. The coating system comprises a mixture of a polyol, an isocyanate, a solvent and a high level of catalyst which accelerates the curing process. The coating is a two-part polyurethane system which is preferably applied by spraying. The coating is particularly well-suited for use on golf balls, and also can be applied to other game balls such as softballs, baseballs, cricket balls.

Abstract: A compact veneer is based on a reaction mixture comprising

Abstract: This invention relates to polyurethane thickeners having particular utility in paints and coatings comprising the reaction product of an isocyanate functional material, a polyether polyol, and a difunctional hydrophilic endcapping material that is reactive with isocyanates.

Abstract: Provided is a low volatile organic content (VOC), isocyanate based curable oil-in-water emulsion of a polyisocyanate crosslinker and a surface active isocyanate reactive material in an aqueous medium, and a process for the preparation thereof. Also provided is a water-in-oil intermediate product to which an aqueous medium can be added to produce the curable oil-in-water emulsions. Such curable emulsions are particularly suited for use in coatings applications.

Abstract: Provided is a low volatile organic content (VOC), isocyanate based curable oil-in-water emulsion of a polyisocyanate crosslinker and a surface active isocyanate reactive material in an aqueous medium, and a process for the preparation thereof. Also provided is a water-in-oil intermediate product to which an aqueous medium can be added to produce the curable oil-in-water emulsions. Such curable emulsions are particularly suited for use in coatings applications.

Abstract: Compact and preferably cellular polyurethane elastomers are produced by reacting a) polyhydroxyl compounds having molecular weights of from 800 to 6000 and, if desired, b) chain extenders and/or crosslinkers having molecular weights of up to 800 [lacuna] c) naphthylene 1,5-diisocyanate and at least one additional aromatic diisocyanate selected from the group consisting of tolylene diisocyanate, diphenylmethane diisocyanate, 3,3′-dimethylbiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and phenylene diisocyanate, and/or aliphatic diisocyanate having from 4 to 12 carbon atoms and/or cycloaliphatic diisocyanate having from 6 to 18 carbon atoms, where the formative components (a), (c) and, if used, (b) are preferably reacted by the prepolymer method, in the presence or absence of d) catalysts, e) blowing agents and f) additives. Isocyanate prepolymers suitable for this purpose are also described.

Abstract: The present invention provides polyester/polyurethane/vinyl dioxolane based coating compositions containing no or essentially no volatile organic components. Oligomers for forming the coating compositions of the present invention are vinyl dioxolane end-capped polyesters and polyurethane oligomers.

Abstract: The present invention relates to polyaddition compounds, which are solid below 40° C. and liquid above 125° C., are prepared by the reaction of an isocyanate component containing uretdione groups with a polyol containing ester and/or carbonate groups, other than hydroxypivalic acid neopentylglycol ester, and have a) an average isocyanate functionality of 2.0 to 8.0 and a content of free isocyanate groups (calculated as NCO; molecular weight=42) of 2.1 to 6.0 wt. %, b) a content of uretdione groups (calculated as C2N2O2; molecular weight=84) of 10 to 19 wt. %, c) a content of urethane groups (calculated as —NH—CO—O; molecular weight=59) of 10 to 17 wt. % and d) a content of ester groups —CO—O (calculated as —CO—O; molecular weight=44) and/or carbonate groups —O—CO—O (calculated as —CO—O; molecular weight=44) of 1 to 17 wt. %.

Abstract: A method for damping vibration of a substrate comprises the step of applying a liquid material onto the substrate in an ambient environment, wherein, after application to the substrate, the material cures substantially instantaneously in the ambient environment. The damping composition usable therefor comprises a resin component and an isocyanate component. The resin component includes a polymer(s) for imparting tensile strength, hardness and flexibility; an optional chain extender(s) for imparting tensile strength, weatherability, flexibility, adhesion to specific substrates, and hardness; and an optional filler for imparting hardness, flexibility, and specific noise, vibration and harshness blocking characteristics to the after-application, cured surface. The isocyanate component of the composition includes an isocyanate quasi-prepolymer(s) based on a uretonimine modified MDI and a high molecular weight polyether polyol having an isocyanate equivalent content of 15.

Abstract: A curable resin composition comprising a urethane (meth)acrylate having a molecular terminal represented by the following formula (3), 1

Abstract: The present invention provides a flexible two component polyurethane and method for producing the polyurethane. The cured polyurethane is flexible, durable and weather resistant. The polyurethane is suitable for use as a protective layer on various substrates. The flexible polyurethane is the reaction product of solvent-free reaction components. The first component includes one or more polyols, optionally, one or more diols, and a catalyst. The second component includes a primary aliphatic isocyante crosslinker.

Abstract: Difficult-to-bond substrates possessing low surface energies are bonded with moisture curable polyurethane hot melt adhesive comprising a polyurethane prepolymer which is the reaction product of a polyol component and a polyisocyanate component, wherein said polyol component comprises a polyester polyol which is the reaction product of diacid comprising aromatic diacid and optional co-monomer diacid and diol, with the proviso that said diacid is substantially free of phthalic acid or derivatives thereof.

Abstract: A golf ball comprising a center, a cover, and optionally, at least one intermediate layer disposed between the center and the cover, wherein at least one of the center, the cover, and the at least one intermediate layer is formed with a polyurethane composition comprising a reaction product of a prepolymer of at least one polyol and at least one polyisocyanate, and a curing agent of at least one diol. A polyurethane composition, suitable for forming golf equipment, said composition comprising a reaction product of a prepolymer of at least one polyol and at least one polyisocyanate, and a curing agent of at least one diol.

Abstract: Biodegradable polymers for use in forming high strength, degradable plastics and methods of forming the polymers are provided. Broadly, the methods comprise forming and heating a blended mixture of polylactic acid, a starch, and a linkage group for joining or copolymerizing the polylactic acid and starch. Preferred linkage groups comprise an isocyanate moiety, with diphenylmethylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. The reacted mixture can then be formed into the desired final product which has high tensile strength, modulus of elasticity, percent elongation, and thermal stability.

Abstract: A solvent-free, two-component strip coating for metal surfaces is described which comprises the following components: A) 5 to 20% by weight of an optionally substituted aromatic diamine, 0.1 to 5% by weight of a dehydrator, 0.01 to 1% by weight of an accelerator based on tertiary amines, 0.01 to 1% by weight of an accelerator based on organic tin compounds, a polyether polyol based on poly(oxyalkylene) glycols as the remainder; B) 40 to 60% by weight of an aromatic diisocyanate based on a phenylene or toluylene diisocyanate, 40 to 60% by weight of a polyether polyol based (poly(oxyalkeylene) glycols. Despite its freedom from solvents, the strip coating according to the invention has rapid-hardening and rapid-drying properties, can be applied to a metal surface to be treated in a single spray operation and finally can be removed without problem and residue-free.

Abstract: A two-component polyurethane coating composition essentially comprising (A) a polyols component, (B) a polyisocyanate component, wherein the polyisocyanate component (B) comprises at least 30% by weight of a polyisocyanate based on 2-methylpentane-1,5-diisocyanate and a polyisocyanate based on isophorone diisocyanate, the sum of the two polyisocyanates being 100% by weight.

Abstract: Propylene oxide is added to an active hydrogen compound in the presence of an alkali metal hydroxide catalyst in an amount of from 0.05 to 0.5 mole per mole of the active hydrogen compound at a reaction temperature of from 60 to 98.degree. C. at a reaction pressure less than or equal to 4 kg/cm.sup.2 to prepare a polyoxyalkylene polyol which has a hydroxyl value of from 10 to 35 mg KOH/g, a monool content less than or equal to 15 mol %, a Head-to-Tail bond selectivity greater than or equal to 96 percent, and low viscosity. A polymer polyol is prepared by polymerizing an ethylenically unsaturated monomer in the polyoxyalkylene polyol. A flexible polyurethane foam is prepared by reacting the polyoxyalkylene polyol or the polymer polyol with an organic polyisocyanate compound in the presence of a foaming agent, a catalyst, a surfactant, a crosslinking agent and other additives.

Abstract: A sealant for forming a fluid seal between the faying surface of two metallic substrates that are compressively and mechanically joined together. The sealant is a liquid in its pre-cured condition and a dry solid in its cured condition. The transition of the sealant from its pre-cured condition to its cured condition occurs at room temperature. The sealant's curing time is not less than about 10 minutes and not more than about 16 hours. The cured sealant has a Shore A hardness between about 30 and 70. The cured sealant is impermeable and resistant to chemical attack by air, water, common solvents and petroleum fuels. Also, the cured sealant is resistant to compressive cold flow, however, the cured sealant is deformable to conform to an abutting surface or with a layer of similar sealant. The cured sealant is flexible and resistant to temperatures between about -65 degrees F. and about 250 degrees F.

Abstract: A composition comprising in admixture with a polymer, preferably a polyurethane, and a compatible surface-modifying macromolecule having (i) a central portion of a segmented block oligomeric copolymer comprising at least one polar hard segment, and (ii) .varies.-.omega. terminal polyfluoro oligomeric groups, in a surface modifying enhancing amount. The composition is of use in providing articles having improved surface properties, particularly, medical devices having improved resistance to enzyme degradation with acceptable blood compatibility.

Abstract: A polyurethane composition to provide a rigid polyurethane foam suitable for use as a core material in a composite laminate and which polyurethane composition includes an additive compound or oligomer-prepolymer having hydroxy groups for reaction with the diisocyanate of the polyurethane or which has been prereacted with a diisocyanate and which contains after the polyurethane reaction ethylenically unsaturated groups, like allyl or acrylic groups, to react with an unsaturated polyester resin. The invention includes the organic additive oligomer-prepolymer and the hybrid polyester-rigid polyurethane laminates.

Abstract: Thermoplastic polyurethanes are formed from a hydrogenated polydiene diol having from 1.6 to 2 terminal hydroxyl groups per molecule and a number average molecular weight between 500 and 20,000, an isocyanate having two isocyanate groups per molecule, and optionally a chain extender having two hydroxyl groups per molecule. The thermoplastic polyurethanes have excellent resistance to moisture as evidenced by retention of more than 70%, preferably at least 85%, of original tensile strength after aging in water for 7 days at a temperature of at least 70.degree. C. Preparation by a prepolymer method with subsequent addition of the chain extender is preferred.

Abstract: The invention relates to a solvent-free radiation curable, optical glass fiber coating composition containing:a) a urethane oligomer having a functional group capable of polymerization in the presence of actinic radiation, with an average functionality of at least about 1.2, having a vinyl addition polymer as backbone.b) a urethane compound having a functional group capable of polymerization in the presence of actinic radiation, with an average functionality of at least about 1, containing an organic moiety having about 5 or more carbon atoms as backbone.c) a reactive diluent.Furthermore, the invention relates to a solvent-free method for producing a solvent-free, radiation curable urethane oligomer composition.

Abstract: The present invention relates to an ablative fire resistant hydrophilic polyurea foam made from low molecular weight polyols capped with an isocyanate, with the polyol mixture including a fire retardant polyol that preferably includes carborane disilanol, with the fire retardant polyol containing the carborane disilanol imparting superior fire retardancy characteristics. The present invention also relates to a prepolymer for forming the polyurea foam and the present invention especially relates to the use of a carborane disilanol fire retardant polyol. The present invention also relates to a method for forming the polyurea foam and the prepolymer.

Abstract: A polyurethane elastic fiber is prepared from a polyurethane prepolymer by reaction extruding the polyurethane prepolymer and a chain extender, preferably with twin-screw extruder, and melt spinning the resulting polyurethane elastomer from the extrusion. The polyurethane prepolymer is obtained by carrying out a pre-polymerization reaction of a polyester diol and a diisocyanate, wherein the polyester diol comprises two different types of polyol, the first type being poly(tetramethylene adipate) glycol or poly(.epsilon.-caprolactone) glycol and the second type being a reaction product of a diol and dicarboxylic acid having 36 carbon atoms.

Abstract: A urethane top coat prepared by combining a polyol and a blend of an aliphatic diisocyanate and an aliphatic/aromatic polyisocyanate copolymer is provided, along with a method for its use as the top coating for a golf ball. The inventive top coating demonstrates an increased rate of curing compared to other top coatings having similar abrasion resistance and color retention qualities.

Abstract: This invention is a liquid polyisocyanate prepolymer comprising the reaction product of an organic polyisocyanate blend and a polyoxyalkylene polyol, where polyisocyanate blend isA) a diphenylmethane diisocyanate comprising from 50 weight percent to 95 weight percent 4,4'-diphenylmethane diisocyanate, from 5 weight percent to 50 weight percent 2,4'-diphenylmethane diisocyanate, and less than 10 weight percent 2,2'-diphenylmethane diisocyanate, said weight percentages based on the total weight of the ingredients in A);B) a polymethylene polyphenyl polyisocyanate comprising from 30 weight percent to 70 weight percent diphenylmethane diisocyanate, the remainder comprising polymethylene polyphenyl polyisocyanates having functionalities greater than two, said weight percentages based on the total weight of the ingredients in B);C) and optionally a uretonimine-carbodiimide modified diisocyanate comprising from 10 weight percent to 35 weight percent uretonimine-carbodiimide species, the remainder comprising essentia

Abstract: A flexible polyurethane foam prepared by reacting polyisocyanate with polyol and/or polymer polyol containing dispersed polymer microparticles obtained by polymerizing an unsaturated compound, water, catalyst, surfactant and, when needed, crosslinking agent and other auxiliary agents, wherein a portion or the whole of the polyol and/or the polymer polyol is prepared in the presence of a compound having a nitrogen-phosphorus double bond as a catalyst, have excellent wet compression set, fatigue by constant-load pounding and dynamic durability.

Abstract: A method for preparing a polyurethane flexible or rigid foam by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a silicone surfactant, and a cell opener characterized in that the cell opener comprises the reaction product of a C1-C20 hydrocarbyl group-containing organic acid anhydride and a substituted phenol which may be alkoxylated or an alkoxylated primary alcohol, optionally reacted in the presence of a tertiary amine urethane catalyst.

Abstract: A radiation curable composition comprising a urethane oligomer with a polyester backbone which composition, when cured, has improved hydrolytic stability. The composition comprises a urethane oligomer, having a polyester backbone with a number average molecular weight of less than about 1000, wherein the polyester backbone is at least in part based on a diol component wherein at least one carbon at the .beta.-position with respect to a hydroxyl group bears two carbon-containing substituents having a total of at least three carbon atoms. Alternatively, when the composition comprises a urethane oligomer with a number average molecular weight of less than about 2000, having a polyester polyol backbone with a number average molecular weight of less than about 1000, the polyester backbone is at least in part based on a diol component wherein at least one carbon at the .beta.-position with respect to a hydroxyl group bears at least one carbon-containing substituent.

Abstract: The present invention relates to solvent-free two-component polyurethane adhesive systems with high initial strengths and low levels of migration derived from a select reactants comprising a hydroxyl polyester and an isocyanate containing prepolymer.

Abstract: This invention relates to a new and useful color pigmented moisture curing polyurethane coating that has an adjustable drying time, as well as methods of producing the coating. The coating is suitable for use as a protective and/or decorative coating. The coating comprises one or more specified color pigments, polyisocyanates, polyols, tertiary amines, and blocked amines. The blocked amines, in conjunction with the tertiary amines, allow the coating to dry slowly once the coating has been applied, resulting in a defect free surface. Furthermore, an additional catalyst, comprising a metal catalyst may optionally be added to the coating immediately prior to use in order to speed up the rate of drying of the coating, allowing for very precise control of the drying speed of the coating. Additional optional ingredients may be added to the coating composition, including ultraviolet light stabilizers, wetting agents, solvents, and agents to increase slip and flow.

Abstract: The present invention provides a low softening temperature, fast-setting adhesive package that exhibits high ultimate temperature performance. These adhesives are particularly useful in the manufacture of bonded furnishings which may require the creation of a bond at a relatively low temperature but maintenance of the bond at relatively high temperatures. A preferred adhesive of the present invention comprises a partially reacted blend of an aliphatic polyester and a trifunctional isocyanate. After curing, the adhesive forms an adhesive composition that exhibits high temperature performance.

Abstract: A two component type polyurethane adhesive is provided for fiberglass reinforced plastics which requires no cleaning, preparation or treatment of the surface, and the like. The curative component is a nitrogen-free liquid polyether or polyester in an amount such that in association with a urethane prepolymer component containing free NCO groups, the ratio of the free NCO groups in the prepolymer component to the OH groups in said curative component is at least 1.2 and desirably at least 1.35. Such high NCO/OH ratios have unexpectedly been found to provide good adhesion and especially good humidity adhesion and peel strength adhesion to fiberglass reinforced plastics or metal surfaces which are free from any surface treatment.