CONDUCTIVE TEXTILES

A method of producing electrically conductive metallic structures in or on textiles, which has the following steps: (a) introducing at least one non-conducting precursor compound into a fibre or yarn material during or after the production thereof, wherein the at least one precursor compound is an inorganic metal phosphate compounds, a metal oxide or a spinel of the general formula AB2O4, (b) producing a textile from the fibre or yarn material, (c) irradiating the textile with electromagnetic radiation, preferably with laser light in the regions of the electrically conductive structures to be produced, with the release of metallisation seeds, and (d) electrical or non-electrical treatment of the textile with deposit of metals at the metallisation seeds with the production of conductive structures in the textile.

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Description
SUBJECT-MATTER OF THE INVENTION

The present invention concerns a method of producing electrically conductive metallic structures in or on textiles, the use of selected metal phosphates as precursor compounds in such a method and textiles produced in accordance with the method and having electrically conductive metallic structures.

BACKGROUND OF THE INVENTION

The production of electrically conductive textiles or electrically conductive structures in or on textiles is basically known.

For example for producing conductive textiles electrically conducting fibres or yarns like for example metal wires or conductively impregnated or coated threads can be incorporated in the textile manufacturing procedure. In that case the extent and orientation of the conductive structures in the textile material is determined inter alia by the manner of processing the fibres or yarns to afford the textile material. In a woven material for example the direction of conductivity will depend on whether the incorporated conductive threads are incorporated in the form of warp threads, weft threads or both. Corresponding considerations apply to knitted fabrics, crocheted fabrics and so forth. The implementation of conductivity in or on the textiles, in particular the provision of given conductive structures like circuits, antennae etc. is therefore severely restricted with that method. In addition the conductive fibres or yarns to be incorporated generally differ in respect of structure, strength and/or thickness of the processed non-conductive fibres or yarns, which can require suitably adapted processing machines like for example special looms. In addition the incorporated conductive fibres or yarns, besides conductivity, also influence other properties of the textile material like for example its flexibility, haptic and visual properties which can be unwanted or can also detrimentally influence further processing of the textile material.

To circumvent some of the above-mentioned disadvantages, for example to provide given conductive structures like circuits, antennae etc. on textile material there are methods in which conductive fibres or threads are sewn on to the textile material in the desired structure. Alternatively conductive coatings of the desired structure are applied to the textile material for example in the form of hardening conductive lacquer or the like. Both methods are laborious, work-intensive and often also poorly scalable like for example in the case of large woven fabric areas in the construction sector. Depending on the nature and extent of the applied conductive structures they can detrimentally influence further properties of the textile material like its flexibility, haptic and visual properties and options for further processing of the textile materials, and not infrequently the applied conductive structures have inadequate mechanical resistance and adhesion on the textile material.

Joohan Kim, JeongU Rho, Jong Hyeong Kim, Laser solidification of conductive composites on a fabric surface, Surface & Coating Technology 205 (2010) 1812-1819, describe a further method of producing electrically conductive structures on textile materials, in which a conductive paste is applied over a large area to the textile material. Then, similarly as in the production of conductor tracks using the so-called photoresist method the paste is exposed by means of laser light along the desired structure and in that way fixed or made resistant to a subsequent washing step with which the non-exposed regions of the paste are removed and the conducting structures remain behind. That method however results in large amounts of waste in the form of the washed-off paste which either has to be disposed of or processed in an expensive and complicated procedure. A further disadvantage is that the textile material, similarly as in the above-described application of a conductive lacquer, is provided with the conductive structures only on one side and at the surface.

US 2017/0204510 A1 describes a method of producing a metal-coated non-woven fabric from a polymer material by electrolytic coating with copper or nickel. In that case the entire non-woven material is acted upon with a coating solution, with the result that it is metalised throughout. The method does not allow the application of desired conductive structures. In addition the method is cost-intensive.

To produce specifically conductive structures on a completely conductive textile material, as described hereinbefore, methods are further known in which the material which is conductive throughout is printed upon with an etch-resistant polymer mask and protected thereby, in the regions in which the conductive structures are to be retained. The conductive metal layer is then removed by etching in the regions which are not protected by the polymer mask. The polymer mask is then removed with an organic solvent so that a conductive structure is produced on the woven material. US 2018/0168032 describes an alternative method in which the completely conductive textile material, in the regions in which no conductivity is to be acquired, is printed upon with an etching paste which removes the metallisation. Both methods are highly laborious, cost-intensive and require the use of strongly corrosive agents and disposal thereof.

EP 1 966 431 discloses a further method of producing conductive structures on textiles including printing on the textile material with a printing formulation containing a metal powder and subsequent thermal treatment in which the metal is deposited. A disadvantage here is once again the fact that the conductive metallisation is applied to the textile material on one side.

US 2018/08017 describes a method of producing an electrically conductive textile material in which the surface of the textile material is firstly silanised and then modified with a negatively charged polyelectrolyte. Metal particles are then deposited in a current-free procedure. The method requires a large number of process steps which are in part difficult to control.

Tariq Bashir, Mikael Skrifvars, Nils-Krister Persson, Production of high conductive textile viscose yarns by chemical vapor deposition technique: a route to continuous process, Polym. Adv. Technol. 2011, 22 2214-2221, describe the production of conductive textiles in which viscose fibres are coated by means of chemical vapour deposition (CVD) with a conductive polymer and are then processed to afford a textile material. The fibres obtained exhibited high conductivity but the textile material is made completely conductive with that method.

Liangbing Hu. Yi Cui, Energy and environmental nanotechnology in conductive paper and textiles, Energy Environ. Sci., 2012, 5, 6423-6435, describes the coating of textiles with carbon nanotubes (CNTs). The conductive fibres produced in that way exhibited good mechanical properties. However the high costs for CNTs are a decisive factor, why that technology hitherto could not gain acceptance.

OBJECT

The object of the present invention is to provide a method which is improved over the state of the art of producing electrically conductive metallic structures in or on textiles, including highly complex structures which can be produced individually for individual textiles, which is comparatively simple, inexpensive, precise and resource-friendly and even with ongoing and/or repeated loading of the textile material, for example when washing, provides stable and long-lived conductive structures which comparatively little impair the properties of the textile material in terms of processing and/or use.

DESCRIPTION OF THE INVENTION

According to the invention that object is attained by a method of producing electrically conductive metallic structures in or on textiles, which has the following steps:

    • (a) introducing at least one non-conducting precursor compound into a fibre or yarn material during or after the production thereof, wherein the at least one precursor compound is an inorganic metal phosphate compound, a metal oxide or a spinel of the general formula AB2O4,
    • (b) producing a textile from the fibre or yarn material,
    • (c) irradiating the textile with electromagnetic radiation, preferably with laser light in the regions of the electrically conductive structures to be produced, with the release of metallisation seeds, and
    • (d) electrical or non-electrical treatment of the textile with deposit of metals at the metallisation seeds with the production of conductive structures in the textile.

In the first method step (a) of the method according to the invention there is introduced into an initially not electrically conductive fibre or yarn material at least one inorganic metal phosphate compound which is referred to herein as the precursor compound as it is selected from such compounds which are activatable by means of laser light with the release of metallisation seeds.

The inorganic metal phosphates, metal oxides or spinels used according to the invention as the precursor compounds are preferably temperature-resistant in such a way that even at elevated temperatures as can occur for example in certain textile production methods they remain stable, that is to say in this connection that they are not already activated prior to the laser treatment at the elevated temperatures and in that case already undesirably form metallisation seeds distributed over the entire textile material.

Optionally step (d) can advantageously be followed by a post-treatment of the textile, in which an additional coating is implemented to protect the metallised material. For example the coating can be a covering comprising a suitable polymer material.

Examples of metal oxides or spinels which are suitable according to the invention of the general formula AB2O4, wherein A and B are different metals, include copper-iron-spinel, copper-chromium-spinel, magnesium-aluminium-oxide, copper-chromium-manganese-oxide, copper-manganese-iron-oxide, copper (I) oxide, copper (II) oxide, copper-chromium-oxide, zinc-iron-oxide, cobalt-chromium-oxide, cobalt-aluminium-oxide, magnesium-aluminium-oxide and mixtures thereof.

According to the invention preferred inorganic metal phosphate compounds which are particularly suitable as precursor compounds are selected from:

    • copper hydroxide phosphate, preferably copper hydroxide phosphate of the general formula Cu2(OH)PO4,
    • anhydrous iron (II) orthophosphate of the general formula Fe3(PO4)2 and
    • anhydrous iron (II) metal orthophosphate, iron (II) metal phosphonate, iron (II) metal pyrophosphate or iron (II) metal metaphosphate of the general formula FeaMetb(POc)d,

wherein a is a number of 1 to 5, b is a number of >0 to 5, c is a number of 2.5 to 5, d is a number of 0.5 to 3 and wherein Met represents one or more metals, selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d-block), in particular Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, Co, Ni, Ag, Au, the metals and metalloids of the third, fourth and fifth main groups, in particular B, Al, Ga, In, Si, Sn, Sb, Bi and the lanthanoids, or combinations of the above-mentioned phosphates.

Those compounds afford a large number of advantages over many other metal compounds. They can be produced economically and inexpensively, which has an advantageous effect on the production costs of textiles with electrically conductive structures using the method according to the invention. In addition they enjoy high absorption in the near infra-red range (NIR) while they exhibit only weak absorption in the visible range of electromagnetic radiation. As a result the colour of the textile material is not seriously affected at least in the regions in which no electrically conductive structures are produced, while at the same time they can be efficiently activated by means of laser light, in particular in the NIR range. It is assumed that the high absorption capability of those compounds according to the invention in the NIR range is governed by their crystal structure. In that way a particularly high yield in respect of the radiated laser light in relation to the mass of precursor compound used is achieved. Those properties make it possible to keep the amounts of those components used and thus also the influences thereof on the material properties of the textile material as low as possible.

There are various suitable possible ways of introducing the non-conducting precursor compound into the fibre or yarn material.

In an embodiment of the method according to the invention the fibre or yarn material, during or after production thereof, is acted upon with or is passed through a solution of the non-conducting precursor compound which possibly contains further components like for example a stabiliser or/or synergist which are also described hereinafter. Preferably an aqueous solution is used. Alternatively a solution in an organic or aqueously organic solvent is used. The fibre or yarn material can be acted upon with the solution by spraying, dipping or passing the fibre or yarn material through a bath. In that case the fibre or yarn material is acted upon or soaked with the solution either only in the region near the surface or completely. The fibre or yarn material can then be further processed either moist or after drying with complete or partial removal of the solvent in the next method step.

In a preferred embodiment of the invention the at least one non-conducting precursor compound and possibly additives used, for example a stabiliser and/or synergist, as are described hereinafter, is introduced into the fibre or yarn material by at least one of those substances being suspended as a solid in a spinning solution and then spun through nozzles.

The term “solution” of the non-conducting precursor compound and possibly further components includes in accordance with the present invention both true solutions and also suspensions and dispersions of the constituents.

The operation of acting on the fibre or yarn material with the precursor compound can also be effected directly in various fibre spinning processes. Thus for example the precursor compound can be homogenously distributed in powder form (suspended or dispersed) in the wet spinning operation, for example in the production of viscose fibres, or can be contained disolved in the spinning solution, so that it is absorbed into the fibres in the spinning process. In the melt spinning of polymer fibres the precursor compound can be introduced into a polymer melt and thus incorporated into the fibres in the melt spinning process. In the case of electrospinning the precursor compound can be dispersed in the polymer solution or polymer melt and also spun in the spinning process in the electrical field.

If the precursor compounds are used in the form of solids, for example in powder form in the spinning solution, it is advantageous if the particle size is not greater than the diameter of the spinning fibre. When using spinning nozzles a mean particle size d50 of not more than 4 μm is advantageous, in which case no particles of sizes of more than 10 μm should be involved in order not to clog the nozzles. When using finer nozzles the mean particle size and the maximum absolute particle size are to be selected correspondingly smaller.

The term textiles in accordance with the present invention denotes any kind of material which is produced by bringing together and/or joining fibres or yarns, including non-woven fabrics. The production of the textile from the fibre or yarn material in the second method step (b) of the method according to the invention can be effected using any method known in textile manufacture, for example by weaving, knitting, laying, felting, needling, braiding, tufting, spinning and so forth. Fibres and yarns include natural and/or synthetic materials which can be treated and/or refined prior to, during or after the production thereof mechanically and/or chemically. The production of yarns is usually effected by spinning crude fibres, for example vegetable fibres like cotton, animal fibres like wool or synthetic fibres like viscose or polyester.

Preferably in that respect only one fibre or yarn material which in accordance with step (a) is subjected to the action of the at least one non-conducting precursor compound is used. Alternatively, depending on the respective situation of use and the processing technology it is also possible for fibre or yarn material to be jointly processed with and without a precursor compound in the production of the textiles.

In step (c) of the method according to the invention the laser is irradiated with laser light, with the release of metallisation seeds, in the regions of the electrically conductive structures to be generated. The suitable laser parameters depend on various properties of the textile to be irradiated like textile material, fibre thickness, concentration and nature of the at least one precursor compound and further included components as well as the desired result. The respectively suitable laser parameters can therefore not be specified generally but are to be ascertained in each case by simple tests by the man skilled in the art with knowledge of the invention. The laser parameters to be taken into consideration in that respect include the laser wavelength to be applied, the laser power, the irradiation duration or scanning speed and possibly pulse rate and pulse energy if pulsed laser light is used.

Depending on the respective concentration and type of the at least one precursor compound used and the further included components such as a stabliser and synergist the desired metallisation seeds for subsequent metallisation to provide the conductive metal structures are formed when suitable laser parameters are involved. If laser activation is excessively weak then too few or no metallisation seeds are formed. If however the laser irradiation is excessively strong the textile material can be locally damaged.

The laser light provides that the at least one precursor compound is locally activated, that is to say it is photochemically converted so that metallisation seeds are formed for the subsequent metal deposit. That reaction usually involves reduction of the metal in the precursor compound.

The laser light for carrying out the method according to the invention can be of a wavelength in the range of 200 nm to 12000 nm. A preferred wavelength is in the range of 700 nm to 1500 nm, particularly preferably 850 nm to 1200 nm. Near infra-red lasers like for example NdYAG lasers, IR diode lasers, VCSEL lasers and Excimer lasers are preferred. The use of Excimer lasers as are known from photolithography is suitable. Suitable Excimer lasers are ArF-, KrF-, XeCl-, XeF-, and KrCl-lasers. The use of Excimer lasers makes it possible to produce very sharp contours for the structures. The use of a KrF Excimer laser with a wavelength of 248 nm is particularly advantageous, particularly if the fibre or yarn material from which the textile material is produced is a thermoplastic polymer material. The laser allows structuring without substantial heating and at all events with minimum fusing of the material in the operative area of the laser. In addition a very high definition sharpness is achieved.

The use of Nd:YAG lasers as are known from medical technology is also advantageous. Nd:YAG lasers using wavelengths of 1064 nm, 946 nm, 532 nm or 473 nm are particularly suitable, an Nd:YAG laser using a wavelength of 1064 nm being particularly preferred as in that way the laser radiation procedure can be particularly delicately carried out and little charring or similar degradation reactions of the textile material occur.

According to the invention VCSEL lasers (Vertical-Cavity Surface-Emitting lasers) are also suitable. These involve semiconductor lasers, specifically surface emitters, in which the light is radiated perpendicularly to the plane of the semiconductor chip in contrast to conventional edge emitters in which the light issues at one or two sides of the chip. Advantages of such surface emitters are on the one hand the low manufacturing costs and the low power consumption. On the other hand the radiation profile, with at the same time a lower level of output power, is better in relation to edge emitters. The VCSEL is distinguished in that it is available in single-mode form and the wavelength is tunable. That makes it possible to specifically select the appropriate wavelength, for example the wavelength at which the metal phosphate compound used according to the invention presents the highest absorption or at which disturbing effects in respect of laser irradiation are kept particularly low. In that way it is possible in accordance with the invention to achieve a highly precise laser structuring result.

The production of the metallic conductive structures requires in the last stage (d) metallisation which can be carried out by means of electrical current or current-less (chemically reductively or electrolytically or galvanically). In that case metals are deposited on the activated structures (metallisation seeds).

Current-less chemically reductive metallisation can advantageously be effected in a wet-chemical process in a metal bath, preferably in a copper, nickel, silver or gold bath, particularly preferably in a copper bath. Suitable technologies and methods for that purpose are known to the man skilled in that art. Chemically reductive metallisation has the advantage over electrolytic metallisation that in that method the semiconductors which are often required and which serve as current bridges between mutually insulated regions of the conductive structures are not required and, unlike the situation with electrolytic metallisation, do not have to be subsequently removed again in a further process step.

After metal deposit the textile is desirably washed and dried. In further steps coatings can also be applied for protection purposes or for enhancing functionality.

The electrically conductive structures produced on textiles according to the method of the invention can be for example electrical circuits, sensors, heating elements or antenna structures for the most widely varying applications. They can be connected to further electronic components. Textiles with electrically conductive structures thereon can also be used for screening in relation to electromagnetic radiation. The possible application options are multiple.

In an embodiment of the method according to the invention in addition to the at least one precursor compound at least one stabiliser is introduced into the fibre or yarn material during or after production thereof, which is selected from compounds of the group consisting of Brönsted acids and Lewis acids, wherein a Brönsted acid is defined as a proton-transmitting compound and a Lewis acid is defined as a non-proton-transmitting electron-deficient compound.

It was surprisingly found that the use of a stabiliser according to the invention in combination with the at least one precursor compound creates particularly desirable reaction conditions for the production of electrically conducting structures under the effect of a laser. It was further established that the stabliser prevents or at least reduces unwanted degradation reactions due to chemical and mechanical effects.

The term Brönsted acid in accordance with the present invention indicates a compound which acts as a proton donor and can transfer protons to a second reaction partner, the so-called Brönsted base. In that respect the Brönsted acid is defined as that compound whose pKs value is less than that of the reaction partner. In the context according to the invention the pKs value of the Brönstead acid is less than the pKs value of the water which is 14.

The term Lewis acid in accordance with the present invention denotes a compound which acts as an electrophilic electron pair acceptor and thus partially or completely acquires from a second reaction partner, the so-called Lewis base, an electron pair, with the formation of an adduct. The Lewis acids in accordance with the present invention include compounds i) with an incomplete electron octet, like: B(CH3)3, BF3, AlCl3, FeCl2, ii) metal cations as central atoms in chemical complexes, iii) molecules with polarised multiple bonds, iv) halogenides with unsaturated coordination like for example SiCl4 or PF5, and v) other electron pair acceptors, for example condensed phosphates.

According to the invention the at least one precursor compound and the stabiliser can be introduced simultaneously or successively into the fibre or yarn material during or after production thereof.

The Brönsted acids and/or Lewis acids used as a stabiliser according to the invention are desirably selected from such acids which are temperature-resistant in such a way that in the processing procedure they remain stable and do not degrade under those and other conditions involved.

According to the invention Brönsted acids which are preferred and suitable as the stabliser include oxyacids of phosphorus with phosphorus in the oxidation stage +V, +IV, +III, +II or +I, sulphuric acid, nitric acid, hydrofluoric acid, silicic acid, aliphatic and aromatic carboxylic acids and salts of the above-mentioned acids.

Preferably the oxyacids of phosphorus and salts thereof are selected from phosphoric acid, diphosphoric acid, polyphosphoric acids, hypodiphosphoric acid, phosphonic acid, diphosphonic acid, hypodiphosphonic acid, phosphinic acid and salts of the above-mentioned acids. The aliphatic and aromatic carboxylic acids and salts thereof are preferably selected from acetic acid, formic acid, oxalic acid, phthalic acid, sulphonic acids, benzoic acid and salts of the above-mentioned acids. Acids are advantageous which do not deteriorate during introduction of the stabiliser into the fibre or yarn material, do not attack same and influence the material properties thereof not at all or only slightly.

According to the invention Lewis acids which are preferred and suitable as the stabliser include sodium-aluminium-sulphate (SOS), monocalciumphosphate-monohydrate (MCPM), dicalciumphosphate-dihydrate (DCPD), sodium-aluminium-phosphate (SALP), calcium-magnesium-aluminium-phosphate, calcium polyphosphate, aluminium chloride, boron trifluoride, magnesium polyphosphate, aluminium hydroxide, boric acid, alkyl borans, aluminium alkyls, iron (II)-salts and mixtures of the above-mentioned. Lewis acids have the advantage over Brönsted acids that during the processing and structuring procedure they do not separate off and liberate water which could result in foaming or oxidation reactions on the part of the metal phosphate compound.

In an embodiment of the invention the stabiliser includes a combination of at least one Brönsted acid and at least one Lewis acid. Such a combination has the advantage that the generally very high stability of the diversely available Brönsted acids can very easily provide advantageous conditions for the production of electrically conducting structures and enhanced stability of the precursor compound in the processing step. At the same time the use of the at least one Lewis acid can provide that water which is possibly liberated and which could adversely affect the result of laser radiation can be caught.

In a further embodiment of the invention in addition at least one synergist is introduced into the fibre or yarn material during or after manufacture thereof, which is selected from metal phosphates, metal oxides or mixtures thereof. Preferably the metal atoms of the metal phosphates, metal oxides or mixtures thereof are selected from the group consisting of Cu, Au, Ag, Pd, Pt, Fe, Zn, Sn, Ti and Al. It was surprisingly found that the synergist promotes the process of metal complex degradation and metal deposit on the fibre or yarn material. Particularly preferred synergists suitable according to the invention are selected from the group consisting of copper phosphate, tricopper diphosphate, copper pyrophosphate, tin phosphate, zinc phosphate, titanium oxide, zinc oxide, tin oxide and iron oxide. The synergists used are desirably so selected in respect of their temperature resistance that they remain stable in the processing procedure and do not degrade in the baths used for the metallisation operation.

Preferably the at least one non-conducting precursor compound in the method according to the invention, with respect to the solid of the precursor compound, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % or at least 0.1 wt % or at least 0.5 wt % and/or at most 15 wt % or at most 10 wt % or at most 5 wt % or at most 2 wt % of the dry fibre or yarn material.

An excessively small proportion involves excessively low density of precursor compound, whereby poorly produced electrically conductive structures can result whereas an excessively high proportion of precursor compound can lead to impairment of the material properties of the textile material.

Preferably the stabiliser in the method according to the invention, with respect to the solid of the stabiliser, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % or at least 0.1 wt % or at least 0.5 wt % and/or at most 15 wt % or at most 10 wt % or at most 5 wt % or at most 2 wt % of the dry fibre or yarn material.

An excessively low proportion involves an excessively low density of stabiliser, whereby the positive effect of the stabiliser in relation to the formation of the electrically conductive structures and the stability in the processing procedure can be reduced whereas an excessively high proportion of stabilier can lead to impairment of the material properties of the textile material.

Preferably the synergist in the method according to the invention, with respect to the solid of the synergist, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % or at least 0.1 wt % or at least 0.5 wt % and/or at most 15 wt % or at most 10 wt % or at most 5 wt % or at most 2 wt % of the dry fibre or yarn material.

An excessively low proportion involves an excessively low density of synergist, whereby the positive effect of the synergist in relation to the formation of the electrically conductive structures and the stability in the processing procedure can be reduced whereas an excessively high proportion of synergist can lead to impairment of the material properties of the textile material.

Suitable amounts and a suitable relationship of precursor compound and optionally stabiliser and/or synergist can be ascertained by simple tests by the man skilled in the art for a given fibre or yarn material or textile material to be produced therefrom, with knowledge of the invention.

Fibre or yarn material suitable according to the invention for the production of textiles with electrically conductive metallic structures according to the method according to the invention include but are not limited to cotton, wool, flax, hemp, viscose, polyamide, polyurethane, polyacrylonitrile, cellulose acetate, polyesters like PET, PBT etc., polyolefins like PE, PP and so forth and copolymers like elastane.

The invention further includes the use of at least one inorganic metal phosphate compound selected from the group consisting of:

    • copper hydroxide phosphate, preferably copper hydroxide phosphate of the general formula Cu2(OH)PO4,
    • anhydrous iron (II) orthophosphate of the general formula Fe3(PO4)2 and
    • anhydrous iron (II) metal orthophosphate, iron (II) metal phosphonate, iron (II) metal pyrophosphate or iron (II) metal metaphosphate of the general formula FeaMetb(POc)d, wherein a is a number of 1 to 5, b is a number of >0 to 5, c is a number of 2.5 to 5, d is a number of 0.5 to 3 and wherein Met represents one or more metals, selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d-block), in particular Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, Co, Ni, Ag, Au, the metals and metalloids of the third, fourth and fifth main groups, in particular B, Al, Ga, In, Si, Sn, Sb, Bi and the lanthanoids, or combinations of the above-mentioned phosphates or a metal oxide or a spinel of the general formula AB2O4 for the production of electrically conductive metallic structures in or on a textile.

Preferably the at least one inorganic precursor compound is used in combination with a stabiliser and/or with a synergist as are defined herein.

The invention also includes a textile which is or can be produced in accordance with the method of the invention and having electrically conductive metallic structures. A textile produced in that way differs from known textiles with electrically conductive metallic structures not only by the advantageous manufacturing method according to the invention but also by virtue of the resulting advantageous structural differences as are described herein and which result in the advantages also described herein, for example in regard to the particularly stable and durable metallization.

The method according to the invention has many advantages over the known methods in the state of the art. The production of electrically conductive metallic structures on textiles is substantially simplified by the method of the invention and can be carried out at lower cost. Highly individual electrically conductive metallic structures can be easily applied to individual or a few textiles without the method of textile manufacture in itself having to be reconfigured. It is sufficient in regard to the textiles to suitably program the usually electronically controlled irradiation operation with electromagnetic radiation, preferably with laser light.

Structuring by means of laser irradiation makes it possible to produce very precisely and quickly even complex electrically conductive structures. It is possible to dispense with the use of resist substances like for example polymer masks whereby it is possible to save on additional chemicals and process steps to a considerable degree. Complex etching and washing steps which are difficult to handle are not required. The method according to the invention is thus highly resource-sparing and does not require laborious and expensive disposal or re-processing of environmentally polluting chemicals. In the method according to the invention the wastage rate is low in comparison with many other known methods, whereby considerable costs can be saved.

A particular advantage of the method according to the invention lies in particular in the stability of the electrically conductive structures produced. It was found that the metallisation created with the method according to the invention can be performed in such a way that the fibres of the textile are metallised completely and cohesively from all sides and a highly stable, resistant and durable metallisation is achieved thereby. At the same time the properties of the textile material are comparatively little impaired in terms of processing and/or use.

The invention will now be further described by means of embodiments by way of example and examples of manufacture for anhydrous iron (II) orthophosphate of the general formula Fe3(PO4)2 and anhydrous iron (II) metal orthophosphate, iron (II) metal phosphonate, iron (II) metal pyrophosphate or iron (II) metal metaphosphate of the general formula FeaMetb(POc)d which are suitable according to the invention as precursor compounds. The attached Figures show X-ray diffraction diagrams of the metal-phosphate compounds produced in accordance with the production examples.

FIG. 1 shows the X-ray diffraction diagram of anhydrous Fe2P2O7 produced in accordance with the invention according to production example 1,

FIG. 2 shows the X-ray diffraction diagram of a phase mixture of anhydrous Mg1.5Fe1.5(PO4)2 and Fe3(PO4)2 produced in accordance with the invention according to production example 2,

FIG. 3 shows the X-ray diffraction diagram of anhydrous Fe3(PO4)2 produced according to the invention in accordance with production example 3,

FIG. 4 shows the X-ray diffraction diagram of anhydrous KFe3(PO4) produced according to the invention in accordance with production example 4,

FIG. 5 shows the X-ray diffraction diagram of anhydrous KFe0.90Zn0.10(PO4) produced according to the invention in accordance with production example 5,

FIG. 6 shows the X-ray diffraction diagram of anhydrous KFe0.75Zn0.25(PO4) produced according to the invention in accordance with production example 6,

FIG. 7 shows the X-ray diffraction diagram of anhydrous KFe0.75Mn0.25(PO4) produced according to the invention in accordance with production example 7,

FIG. 8 shows the X-ray diffraction diagram of anhydrous BaFeP2O7 produced according to the invention in accordance with production example 8, and

FIG. 9 shows conductive metallic structures produced in accordance with example 5 on viscose textile.

 EXAMPLES X-Ray Diffractometry (XRD)

Taking the products produced in accordance with the examples hereinafter X-ray diffraction measurements were carried out on a diffractometer of the type D8 Advance A25 (Bruker) using CuKα-radiation.

The products and their crystal structures were identified on the basis of suitable reference diffraction diagrams (Powder Diffraction Files; PDF-cards) of the database of the ICDD (International Centre for Diffraction Data), formerly JCPDS (Joint Committee on Powder Diffraction Standards). Insofar as no PDF cards were available for the products manufactured PDF-cards of isotype compounds (=compounds of the same structure type) were used.

Elementary Analysis

To ascertain and confirm the stoichiometries of the products manufactured elementary analyses were carried out by means of X-ray fluorescence analysis (XRF) using the Axios FAST spectrometer (from PANalytical).

Production Example 1 Anhydrous Fe2P2O7

A suspension comprising

i) 35.5 kg of iron (II) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 16.5 kg of 98% phosphonic acid [H3PO3],

iii) 26.5 kg of 75% phosphoric acid [H3PO4] and

LM: 220 kg of water

was sprayed granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 4 h in a formine gas atmosphere (5 vol-% H2 in N2) at 700° C. The result obtained is an almost colourless to pink-coloured product. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 1. The product was identified on the basis of the PDF-card 01-072-1516.

Production Example 2 Phase Mixture of Anhydrous Mg1.5Fe1.5(PO4)2 and Fe3(PO4)2

A suspension comprising

i) 8.45 kg of iron (II) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 7.95 kg of 98% phosphonic acid [H3PO3],

iii) 19.6 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 8.43 kg of magnesium carbonate [MgCO3] and

LM: 160 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 3 h in a forming gas atmosphere (5 vol-% H2 in N2) at 750° C. An almost colourless product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 2. The product was defined on the basis of the PDF-cards as a phase mixture comprising a main phase Mg1.5Fe1.5(PO4)2 (PDF-card 01-071-6793) and a secondary phase Fe3(PO4)2 (PDF-card 00-49-1087).

Production Example 3 Anhydrous Fe3(PO4)2

A suspension comprising

i) 21.75 kg of iron (II) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 12.15 kg of 98% phosphonic acid [H3PO3],

iii) 10.3 kg of iron (III)-phosphate-dihydrate [FePO42H2O] and

LM: 140 kg of water

was spray granulated. The granulate obtained in that way was temperature treated in a rotary furnace for a mean residence time of 90 minutes in a forming gas atmosphere (5 vol-% H2 in N2) at 750° C. An almost colourless product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 3. The product crystalises in the graftonite structure and was defined on the basis of the PDF-card 00-49-1087. The product was ground in such a way that 50 wt % of the product was of a particle size of less than 3 μm.

Production Example 4 Production of Anhydrous KFe(PO4)

A suspension comprising

i) 11.80 kg of iron (III) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 10.70 kg of 98% phosphonic acid [H3PO3],

iii) 24.8 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 29.8 kg of 50% potash [KOH]

v) 1.0 kg of 75% phosphoric acid [H3PO4] and

LM: 110 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 3 h in a forming gas atmosphere (5 vol-% H2 in N2) at 650° C. A pale light green product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 4. The product was identified on the basis of the PDF-card 01-076-4615).

Production Example 5 Anhydrous KFe0.90Zn0.10(PO4)

A suspension comprising

i) 10.60 kg of iron (III) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 9.65 kg of 98% phosphonic acid [H3PO3],

iii) 22.30 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 2.15 kg of zinc oxide [ZnO]

v) 29.8 kg of 50% potash [KOH]

vi) 4.15 kg of 75% phosphoric acid [H3PO4] and

LM: 120 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 2 h in a forming gas atmosphere (5 vol-% H2 in N2) at 600° C. A light grey product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 5. The product involves a new structure type which seems to be closely related to the KFe(PO4) structure in accordance with PDF-card 01-076-4615.

Production Example 6 Anhydrous KFe0.75Zn0.25(PO4)

A suspension comprising

i) 8.85 kg of iron (III) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 8.05 kg of 98% phosphonic acid [H3PO3],

iii) 18.60 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 5.40 kg of zinc oxide [ZnO]

v) 29.8 kg of 50% potash [KOH]

vi) 9.30 kg of 75% phosphoric acid [H3PO4] and

LM: 120 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 2 h in a forming gas atmosphere (5 vol-% H2 in N2) at 600° C. A light grey product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 6. The product is not known from the literature. It crystalises isotypically to KZn(PO4) in accordance with PDF-card 01-081-1034.

Production Example 7 Anhydrous KFe0.25(PO4)

A suspension comprising

i) 8.85 kg of iron (III) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 8.05 kg of 98% phosphonic acid [H3PO3],

iii) 18.60 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 8.85 kg of manganese carbonate-hydrate [MnCO3H2O]

v) 29.8 kg of 50% potash [KOH]

vi) 9.30 kg of 75% phosphoric acid [H3PO4] and

LM: 140 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 2 h in a forming gas atmosphere (5 vol-% H2 in N2) at 600° C. A light grey product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 7. The product is not known from the literature. It crystalises isotypically to KFe(PO4) in accordance with PDF-card 01-076-4615.

Production Example 8 Anhydrous BaFeP2O7

A suspension comprising

i) 8.70 kg of iron (III) oxide hydroxide [FeO(OH) or Fe2O31H2O],

ii) 8.20 kg of 98% phosphonic acid [H3PO3],

iii) 19.05 kg of iron (III)-phosphate-dihydrate [FePO42H2O],

iv) 63.09 kg of barium hydroxide-octahydrate [Ba(OH)28H2O]

v) 26.15 kg of 75% phosphoric acid [H3PO4] and

LM: 250 kg of water

was spray granulated. The granulate obtained in that way was temperature-treated in a rotary furnace for a mean residence time of 4 h in a formin gas atmosphere (5 vol-% H2 in N2) at 800° C. A light grey product was obtained. The X-ray diffraction diagram (XRD) of the product is shown in FIG. 8. The product crystalises isotypically to BaCoP2O7 in accordance with PDF-card 01-084-1833.

The following Examples explain the method according to the invention.

Example 1

Iron (II) magnesium phosphate of the formula Fe2Mg(PO4)2 was dry mixed with 1 wt % of disodium dihydrogen phosphate, Na2H2P2O7. 5 wt % of the mixture was incorporated by means of an extruder (type ZSK 18 from Coperion GmbH) into a polyamide 6,6 (Ultramid™ from BASF) and a granulate was produced. The granulate could be processed to give fibres by means of melt spinning.

Example 2 Comparative

3 wt % of copper hydroxide phosphate was incorporated by means of an extruder (type ZSK 18 from Coperion GmbH) into a polyamide 6,6 (Ultramid™ from BASF). The extrusion operation was carried out at the upper end of the recommended temperature range at 285° C. Unwanted discolouration of the plastic occurred. The initially light greenish compound changed its colour to brown. In addition a slight but unwanted deposit of metallic copper on the shaft of the extruder was found.

Example 3

4 wt % of copper hydroxide phosphate and 2 wt % of sodium-aluminium-sulphate (SAS) was incorporated by means of an extruder (type ZSK 18 from Coperion GmbH) into a polyamide 6,6 (Ultramid™ from BASF) and a granulate was produced. The extrusion operation was carried out at the upper end of the recommended temperature range at 285° C. No unwanted discolouration of the plastic occurred and there was no deposit of metallic copper on the shaft of the extruder. It was possible to produce polyamide fibres by way of the melt spinning method.

Example 4

Polyamide fibres produced in Examples 1 and 3 were used to produce textiles by weaving. They were activated by means of laser light of a wavelength of 1064 mm with different laser parameters. For first investigations relating to the metallisation the textile patterns were processed over 120 min in the chemical copper electrolyte at a copper deposit rate of 3-5 μm/h.

Example 5 Production of Electrically Conductive Metallic Structures on a Viscose Textile

In a first step viscose fibres were produced in an industrial viscose spinning process known to the man skilled in the art. Copper hydroxide phosphate (Cu2(OH)PO4; Fabulase 361, Chemische Fabrik Budenheim KG) was added as the precursor compound to the spinning solution. The precursor compound was of a grain size of 3.4 μm (median value) and an exclusion value of the maximum grain size of 10 μm. The viscose fibre obtained had a fineness in accordance with ISO 1144 and DIN 60905 of 1.7 dtex. The loading of the viscose fibre with the precursor compound copper hydroxide phosphate was 3 wt % with respect to the weight of the dry viscose fibre.

In a next processing step non-wovens (spun non-wovens) were produced from the viscose fibres produced, using the so-called spunlace method. In that case respective mixtures of fibres with and without loading with precursor compound were used in defined ratios. Non-woven consisting only of non-loaded fibres was produced as a reference. The non-wovens respectively were of a weight in relation to surface area of 100 g/m2.

TABLE 1 Textiles produced (non-wovens): Textile pattern # Cu2(OH)PO4 loaded fibre [%] Non-loaded fibre [%] 1 (Ref.) — 100%  2 20% 80% 3 80% 20% 4 100%  —

Structures were produced on the textile pattern #4 by means of laser irradiation with different laser parameters. The pulse rate was constant at 100 kHz. The laser power, pulse energy, scanning speed, longitudinal pitch and transverse pitch were varied. “Longitudinal pitch” denotes the spacing between two points of the laser irradiation in the longitudinal direction of a linear structure. “Transverse pitch” denotes the spacing between two points of the laser irradiation transversely to the longitudinal direction of a linear structure. By way of example 3 parameter sets are explained in greater detail. With the parameter sets L1 and L2 the scanning speed at 500 mm/s as well as the longitudinal and transverse pitch at 5 μm were kept constant while the laser power and pulse energy were varied. In the case of L1 the values of laser power and pulse energy were at 2 W and 20 μJ while the values in L2 were at 4 W and 40 μJ. In parameter set L3 the laser power and the pulse energy were increased further to 8 W and 80 μJ. In addition the scanning speed was doubled to 1000 mm/s and the longitudinal and transverse pitch were respectively increased to 10 μm.

A laser installation MicroLine 3D 160i from LPKF with a focus diameter of 60 μm and a wavelength of 1064 nm was used for laser structuring. After laser irradiation the textile patterns were cleaned by a wet chemical procedure.

The textile patterns were firstly visually assessed after laser irradiation but prior to metallisation. Here the structuring with adequate energy input could already be well observed but an excessively high energy input resulted in partial destruction of the textile.

For metallisation the textile patterns were processed over 120 min in the chemical copper electrolyte with a copper deposit rate of 3-5 μm/h.

Good Cu deposit could be observed over wide ranges of the laser parameter sets used, as is shown in FIG. 9 reproducing the modified viscose textile after laser structuring and metallisation (laser parameter set L1 at the left, laser parameter set L2 at the middle and laser parameter set L3 at the right). In general laser parameter sets involving greater longitudinal and transverse pitches like for example parameter set L3 severed the textile to a lesser degree.

In addition it was possible to observe that no closed metal layer was formed by virtue of the condition of the substrate in the investigations. Rather the individual textile fibres were coated in the laser-structured regions upon processing in the Cu electrolyte. Electrical accelerated tests on metallised regions gave electrical conductivity of the structures.

Claims

1. A method of producing electrically conductive metallic structures in or on textiles, which has the following steps:

(a) introducing at least one non-conducting precursor compound into a fibre or yarn material during or after the production thereof, wherein the at least one precursor compound is an inorganic metal phosphate compound, a metal oxide or a spinel of the general formula AB2O4,
(b) producing a textile from the fibre or yarn material,
(c) irradiating the textile with electromagnetic radiation, preferably with laser light in the regions of the electrically conductive structures to be produced, with the release of metallisation seeds, and
(d) electrical or non-electrical treatment of the textile with deposit of metal at the metallisation seeds with the production of conductive structures in the textile.

2. The method according to claim 1, wherein the at least one inorganic metal phosphate compound is selected from the group consisting of:

copper hydroxide phosphate;
anhydrous iron (II) orthophosphate of the general formula Fe3(PO4)2; and
anhydrous iron (II) metal orthophosphate, iron (II) metal phosphonate, iron (II) metal pyrophosphate or iron (II) metal metaphosphate of the general formula FeaMetb(POc)d, wherein a is a number of 1 to 5, b is a number of >0 to 5, c is a number of 2.5 to 5, d is a number of 0.5 to 3 and wherein Met represents one or more metals, selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d-block), the metals and metalloids of the third, fourth and fifth main groups, and the lanthanoids, or combinations of the above-mentioned phosphates.

3. The method according to claim 1, wherein in addition to the at least one precursor compound at least one stabiliser is introduced into the fibre or yarn material during or after production thereof, which is selected from compounds of the group consisting of Brönsted acids and Lewis acids, wherein a Brönsted acid is defined as a proton-transmitting compound and a Lewis acid is defined as a non-proton-transmitting electron-deficient compound.

4. The method according to claim 1, wherein the at least one stabiliser is or includes a Brönsted acid selected from oxyacids of phosphorus with phosphorus in the oxidation stage +V, +IV, +III, +II or +I, sulphuric acid, nitric acid, hydrofluoric acid, silicic acid, aliphatic and aromatic carboxylic acids and salts of the above-mentioned acids.

5. The method according to claim 4, wherein the oxyacids of phosphorus and salts thereof are selected from phosphoric acid, diphosphoric acid, polyphosphoric acids, hypodiphosphoric acid, phosphonic acid, diphosphonic acid, hypodiphosphonic acid, phosphinic acid and salts of the above-mentioned acids and/or the aliphatic and aromatic carboxylic acids and salts thereof are selected from acetic acid, formic acid, oxalic acid, phthalic acid, sulphonic acids, benzoic acid and salts of the above-mentioned acids.

6. The method according to claim 1, wherein the at least one stabiliser is or includes a Lewis acid selected from sodium-aluminium-sulphate (SOS), monocalciumphosphate-monohydrate (MCPM), dicalciumphosphate-dihydrate (DCPD), sodium-aluminium-phosphate (SALP), calcium-magnesium-aluminium-phosphate, calcium polyphosphate, magnesium polyphosphate, aluminium hydroxide, boric acid, alkyl borans, aluminium alkyls, iron (II)-salts and mixtures of the above-mentioned.

7. The method according to claim 1, wherein in addition at least one synergist is introduced into the fibre or yarn material during or after manufacture thereof, which is selected from metal phosphates, metal oxides or mixtures thereof.

8. The method according to claim 1, wherein the at least one non-conducting precursor compound and the optionally used stabiliser and/or the optionally used synergist are introduced into the fibre or yarn material by the fibre or yarn material during or after production thereof being acted upon with a solution thereof or passed through same, wherein the solution is an aqueous solution or a solution in an organic or aqueously organic solvent.

9. The method according to claim 1, wherein the at least one non-conducting precursor compound, with respect to the solid of the precursor compound, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % at most 15 wt % of the dry fibre or yarn material.

10. The method according to claim 2, wherein the at least one stabiliser, with respect to the solid of the stabiliser, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % and at most 15 wt % of the dry fibre or yarn material.

11. The method according to claim 7, wherein the at least one synergist, with respect to the solid of the synergist, is introduced into the fibre or yarn material in an amount which corresponds to at least 0.01 wt % and at most 15 wt % of the dry fibre or yarn material.

12. The method according to claim 1, wherein the laser light used for irradiating the textile has a wavelength in the range of 200 nm to 12000 nm.

13. The method according to claim 1, wherein the fibre or yarn material is selected from the group consisting of cotton, wool, flax, hemp, viscose, polyamide, polyurethane, polyacrylonitrile, cellulose acetate, polyesters, polyolefins, and copolymers of the above-mentioned.

14. A method comprising adding in or on a textile at least one inorganic metal phosphate compound selected from the group consisting of:

copper hydroxide phosphate,
anhydrous iron (II) orthophosphate of the general formula Fe3(PO4)2 and
anhydrous iron (II) metal orthophosphate, iron (II) metal phosphonate, iron (II) metal pyrophosphate or iron (II) metal metaphosphate of the general formula FeaMetb(POc)d, wherein a is a number of 1 to 5, b is a number of >0 to 5, c is a number of 2.5 to 5, d is a number of 0.5 to 3 and wherein Met represents one or more metals selected from the group consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d-block), in particular Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn, Co, Ni, Ag, Au, the metals and metalloids of the third, fourth and fifth main groups, in particular B, Al, Ga, In, Si, Sn, Sb, Bi and the lanthanoids, or combinations of the above-mentioned phosphates; or
a metal oxide or spinel of the general formula AB2O4.

15. The method according to claim 14, wherein the at least one inorganic metal phosphate compound or the metal oxide or spinel of the general formula AB2O4 is added in combination with a stabiliser and/or with a synergist.

16. (canceled)

17. A textile having electrically conductive metallic structures which is or can be produced according to claim 1.

Patent History
Publication number: 20210388532
Type: Application
Filed: Sep 26, 2019
Publication Date: Dec 16, 2021
Applicant: Chemische Fabrik Budenheim KG (Budenheim)
Inventors: David ENGERS (Budenheim), Thomas FUTTERER (Ingelheim), Tobias MOSS (Darmstadt), Gideon RATH (Darmstadt), Rüdiger WISSEMBORSKI (Neuruppin)
Application Number: 17/279,638
Classifications
International Classification: D01F 1/09 (20060101); D01F 1/10 (20060101); D01F 2/08 (20060101); D06M 10/00 (20060101); D06M 10/06 (20060101); D06M 11/83 (20060101);