DE1910445A1 - Electrically conductive elastomeric compounds - Google Patents

Description

Electrically conductive elastomeric materials.

The present invention relates to elastomeric compositions with
electrically conductive properties and a method for
Metallization of objects using such masses. In particular, it relates to a composition of
an elastomer, the oxides and / or hydroxides including those hydroxides generally considered to be hydrated oxides of cadmium, indium, lead and zinc
contains dispersed and a process for making metallized articles using such compositions.

Synthetic polymers, as a general class, are electrically non-conductive. In fact, it was precisely this quality which gave rise to the establishment of the synthetic polymer industry and strong impetus for its further development, because there was a need for electrical insulating materials.

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With the development of the electrical industry, there was a need for materials that, although not as conductive as metals, nevertheless have sufficient conductivity that they can be used, for example, as corona screens or for installation as a separate layer in the insulation could be used to prevent a spray discharge as it would completely break down the electrical isolation. With the development of the synthetic polymer industry, these materials were created also outside of their applications in electrical uses areas of application for jewelry and utility purposes such as for example in coatings, synthetic fibers, films, etc.

Because of the electrically insulating nature of these polymers, the articles made from such fibers and films show the disruptive property of building up static charges on their surfaces, as a result of which dust in turn builds up from the Adhere to air and other substances on their surfaces. Many attempts have been made to equip such objects with a surface which dissipates the electrostatic charges so that these objects no longer build up static charges as easily. Conductive surfaces are also desirable for electroplating non-conductors for jewelry and other uses, such as for decorative patterns, printed circuits, etc. Applications are also available where there is a need for Manufacture of compositions such as conductive fabrics, especially in the form of conductive tapes, which is a have certain conductivity in order to regulate the electrical current flowing in one containing such a composition Line flows.

Much effort has been made to develop synthetic, electrically conductive polymers. Than the synthetic Ion exchange resins were developed with the hope that these products could be used as conductive polymers could find. One soon had to experience, however, that under the influence of an electrical potential a large part the conductivity was ionic in nature, and the ionic groups

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of the polymer, depending on the respective charge of the ionic Group in the polymer, migrated to either the anode or the cathode. This property is undesirable because it to deplete the inner part of the polymer in ionic groups leads and thereby leads to an increase in resistance and a degradation of the polymer.

Other attempts at solving this problem have been to use conductive Fillers of a metallic or other type, such as incorporating carbon blacks into the polymers in order to obtain compounds, that were conductive. Since the amount of filler determines the conductivity of the composition, the maximum conductivity depends such compositions depend on the maximum amount of filler that can be incorporated into the composition without it whose mechanical properties are influenced. Although these compositions are electrically conductive, they have the disadvantage on that in their galvanic treatment the quality of the metallic deposition and the possibility of the deposition of the density (number per unit of the surface) of the conductive particles in the surface depends, the surface of which is at least is partially not covered by the polymer base. In addition, there is the adhesion of the applied metal to the substrate generally very bad; this is especially true when carbon is used as a conductive filler. Also at Using metal particles as a filler, the adhesiveness does not meet the requirements of many commercial ones Applications are placed on the coated objects. Metal particles are also difficult to disperse, them remain suspended in the paint or varnish and are generally available in such a coarse grain size that even after Deposition of another metal must be ground and polished so that the desired surface condition is obtained.

In the past few years, the production of metallized Plastic items increased sharply. As already mentioned, this means that plastic objects are with a

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Coating has been provided that the desired surface was first coated with an electrically conductive varnish or paint, the generally contained either carbon or metal powder as a filler in sufficient quantities to provide a surface received that could be electroplated. However, it left both the adhesion of the conductive paint to the substrate and the applied metal film on the conductive paint left a lot to be desired. During use, the applied metal cared for as a result of either failure of the bond between the metal and the conductive paint or the bond between the The conductive paint and the substrate will flake off the surface of the plastic or form efflorescence. This failure occurred particularly when the coated article Was subjected to temperature fluctuations.

To solve this problem, special plastics have been developed, in which a thin metal film is deposited by means of a chemical treatment of the surface with the help of electroless deposition processes and then a thicker metal coating could be applied with the help of galvanic processes. Although this The method that prevents the applied metal from peeling off during use still requires use certain plastics and is extremely time consuming and expensive.

It is an object of the present invention to provide a composition which is used for the manufacture of an object can, which has sufficient conductivity on at least part of its surface, so that it can be with the help of galvanic or electroless plating processes.

Another object of the present invention is to provide a composition which can be used to produce a surface coating with high conductivity on a specific surface of any non-conductive substrate, such as sheets, plates, films _, fibers or other shaped objects.

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The present invention has further improved manufacturing Metallized objects made of non-conductive material for the task.

Another object of the present invention is a method to achieve the above-mentioned tasks.

These objects are achieved according to the invention with the aid of a composition which has an elastomer which has a Metal composition contains in powder form selected from the group consisting of the oxides and hydroxides, including the Hydroxides generally selected as hydrated oxides of cadmium, indium, lead and zinc including their mixtures and using the above compositions by means of a process for the manufacture of an article, the Surface is at least partially electrically conductive to a sufficient extent so that these surfaces are coated with a metal can be.

The invention is described in more detail below with reference to the drawings in the

Pig. 1 is an isometric view of a substrate that has electrically insulating properties and on which a Pattern was formed in a manner according to the invention, and

Figure 2 illustrates a cross-sectional view of a substrate comprising has electrically insulating properties and has a coating adhered thereon on its surface and which has been enlarged to reveal details of the polymer composition according to the invention, and

Figure 3 is a cross-sectional view of a substrate having electrically insulating properties supported on its surface carries an adhesive coating of an electrically conductive polymer on which an adhesive coating of a metal according to the invention was deposited.

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It has been found that electrically conductive polymers by dispersing an oxide or hydroxide of cadmium, indium, lead and zinc or their mixtures in an elastomer can be. If necessary, other dyes, pigments, fillers, flow aids such as agents which thixotropy can be used increase, etc., as well as vulcanizing or curing agents for elastomers be present. As detailed below the amount of elastomer should be sufficient to impart film-forming properties to the compositions and the amount of metal oxide or hydroxide should be so great that the metal compound is in one of these compositions produced film can be electrochemically reduced to the metal.

As mentioned above, the metal compounds that can be used in the elastomeric matrix are the oxides and hydroxides including the hydroxides generally viewed as hydrated oxides of cadmium, indium, lead and zinc will. These compounds must be able to be ground into fine powders so that they can be dissolved in a solution of the elastomer can be easily dispersed and the films or coatings made therefrom will be smooth. Form cadmium and zinc well-defined hydroxides that can be ground into powders. "The hydroxides of indium and lead are not well-defined compounds and are generally considered to be hydrated oxides. As all these hydroxides and hydrated oxides by heating can easily be converted into oxides at relatively low temperatures, since im A longer time is required within the scope of the process according to the invention and since the oxides are more readily available commercially are, the oxides of the four metals mentioned are preferred.

Lead oxides are commercially available in various oxidation states. The so-called black oxide or suboxide is actually a mixture of PbO and varying amounts, generally 10 to 15% by weight , of free lead. The other oxides PbO,

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Pb ^ O ₁ J and PbO ₂ are true oxides. The latter two oxides are oxidizing agents that have a deleterious effect on the elastomeric matrix. In addition, they are not reduced to metal as easily as PbO. For this reason, PbO, either as it is known as black lead or black oxide, is preferably used and referred to as the oxide of lead (II) or as lead (II) oxides.

Although the indium oxides are known in various oxidation states as In ₂ O, InO, In ₂ O, and In ^ Oj, In ₂ O and InO are produced by reducing the In ₂ O, and can easily be converted into In ₂ O, and In ^ Oj. should be oxidized, In, Oj. be a mixture of In ₂ O, and InO. In contrast to lead, the indium oxide in the highest oxidation state as In ₃ O is not an oxidizing agent and is reduced to metal in the process according to the invention just as easily as the other indium oxides. All indium oxides can therefore be used in the compositions according to the invention; However, InpO-z is preferred because it is the most readily available.

The oxides of cadmium and zinc are only known in one oxidation state as CdO and ZnO and are both easily reduced to metal in the process according to the invention. CdO and In ₂ O are unique in the compositions of the present invention in that the fibers, films, coatings, etc. containing either or both of these oxides have semiconductor properties, while fibers, films, coatings, etc. have their hydroxides or the Zinc or lead compounds contain such a high resistance that they are insulators for all practical purposes, surprisingly they can be reduced to metals using the method according to the invention, but this is preferably done by the separate electrochemical step which will be described below. If the reduction and the deposition of the metal are carried out at the same time, then CdO or In ₂ O are preferably used, where Cd ″ because of its

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- 8 is most beneficial at a considerably lower cost.

The compounds especially in dust and powder form Like lead compounds, cadmium is highly toxic. For this reason, great care must be taken when handling these substances are expended. Since zinc oxide or hydroxide are not considered to be toxic, they are preferable from this point of view. Zinc oxide is preferable to all metal compounds that can be used. It is non-toxic and in the form of a fine powder Easily available at low prices. Like the other metal compounds, it is easily dispersed in the solution of the elastomer, which can be used to produce very smooth coatings. The zinc oxide in the coating can be easily reduced and results in a smooth, very conductive coating that can easily be electroplated. The electrodeposited metal adheres very well to the substrate.

Surprisingly, it was found that other metal compounds, such as metal oxides, sulfides, etc. or conductive ones Carbon blacks cannot be used in place of the oxides and hydroxides of cadmium, indium, lead and zinc. A replacement of this kind leads to masses which in most cases cannot be galvanically coated and in the few cases. in which this composition is electroplated with a coating This exhibits poor adhesiveness and is generally very easy to peel from the conductive coating will. If the maximum .by using the metal compounds according to the invention, i.e. cadmium, indium, lead or Zinc oxides or hydroxides achievable peel strength, not required, then these substances can be used together and as a diluent find cost-saving use for the metallic compounds according to the invention. Find it this way If they are used, however, they should generally not be used in quantities greater than 25 vol.? the total volume of the diluent and the metal compound according to the invention can be used so that the subsequently electrodeposited metal

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- 9 retains sufficient liability.

If an object, the surface of which has been at least partially coated with a composition according to the invention, in a Entered an electroplating bath, with the surface coating serving as the cathode, then several competing ones occur Reactions to. If the electroplating bath contains either an acid, a chelating agent or a complexing agent, then there is a tendency the Met all connection to dissolve something. This tendency dissolving is much less when the bath is neutral or alkaline and either free of complexing agents or if the amount of complexing agent is sufficient to bind the metal ions already present in the galvanic solution as complexes, does not exceed the required amount. Around To keep the dissolution of the metal compound as low as possible, it is therefore advisable to use neutral or alkaline electroplating baths to use. The desired main reaction is that the metal compound is first reduced to the free metal and then the metal ions of the electroplating bath as a firmly adhering metallic coating on the surface, caused by the reduction the metal particles obtained from the metal oxides are precipitated. These reduction and deposition reactions set in Point at which electrical contact has been made and spread outward until the whole, originally the Metal compound containing surface is coated with metal. By using multiple connections on the conductive surface to the cathode induction and metal deposition can be effected at each terminal and spread to each coated one Surface merges with the others.

The composition containing the metal compound was a surface coating or film on a transparent substrate and about 0.02-0.05 mm (l-2mils) thick, it was then surprisingly found that when the object was electroplated the reduction of the metal bond to the metal not only on the surface but through the entire depth of the coating

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and that the deposited metal penetrated into the depth as it was deposited on the surface and thereby formed a firmly adhering metal coating on such objects. This could therefore be perceived by the eye because the color of the layer, which came from the metal compound has been replaced by the gray color of the metal, surprising was the finding ₅ that the bond between the elastomer and sustained by the by the reduction of the dispersed metal compound Metal particles was not noticeably affected by the reduction.

It was also surprising to find that when an object whose surface was coated with any of these metal compounds containing composition is introduced into one of the various non-galvanic plating baths containing a reducing agent, after an induction period such a surface is catalytically active and the metal ions precipitates in the non-electroplating solution in the form of a continuous metal coating over the entire surface of the coating in contact with the solution. Whether the reducing agent contained in such a non-electroplating plating solution first reduces part of the metal compound to the metal which then constitutes the active catalyst which effects the non-electroplating reaction is not known, but it is very possible. Observation indicates that if such a reduction reaction occurs, it does not proceed to the depth as observed when the metal coating is formed in an electroplating solution. On the other hand, the fact that the metal deposition not * but only used in the non-galvanic plating bath immediately after a long period of time that the metal deposition in the galvanic plating bath so long does not begin until the present reducing agent at least part of at the Surface of the coating has reduced particles of the metal compound present to metal .

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Since the metal deposition only occurs electrochemically after the metal compound has been reduced to metal, there is a tendency near the electrical connection for the formation of a somewhat stronger precipitate, which decreases in strength towards the outside, since the metal connection is in this direction is reduced to metal. However, this difference in strength is not very pronounced. As mentioned above If non-electrodeposition processes are used, there is a delay before the metal settles into the non-galvanic bath begins to deposit on the object. However, as soon as deposition begins, it occurs the entire surface of the coating in contact with the solution and containing the metal compound. To both the galvanic as well as the non-galvanic deposition processes To accelerate, it has proven to be very useful to have the metal compound at least on the surface of the coating to be reduced to the metal by cathodic treatment with an electrolyte. Such reduced coatings are catalytically effective for the non-electrodeposition reaction and generally have high conductivity. the electrodeposition or non-electrodeposition occurs instantly all over the coated surface created in this way has been reduced.

Although any aqueous electrolyte that generates hydrogen at the cathode is sufficient for the reduction, the preferred electrolyte is alkaline or neutral, such as an aqueous solution of an alkali metal hydroxide, carbonate or bicarbonate or an alkali metal salt of a mineral acid, preferably HpSO ₁ ^. These solutions are simple, easy to obtain and do not lead to any harmful dissolution of the metal compound during cathodic treatment, as can occur with a satirical electrolyte. As observed with the electroplating of the metal compound-containing compositions, the cathodic treatment reduces the metal compound through a thin film or

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Coating through completely to the metal without affecting the adhesion between the particles and the elastomeric matrix would be affected.

The reduction process proceeds more slowly in the direction of the depth of the coating than on the surface. Will therefore thicker coatings or films either in a separate process stage or reduced during the deposition process, the reduction of the surface is completed first, without thereby excluding the reduction in the depth of the coating fc would be. If necessary, the reduction reaction is continued to generate free metal for at least the first 0.25 mm (10 mils) below the surface. To the Galvanic or non-galvanic deposition, only a reduction of the surface is necessary, although the simultaneous one Reduction in the depth of the coating significantly increases the adhesion of the deposited metal layer.

Is to be obtained a highly-conductive surface, or a metal may be deposited on such surface, either by means of non-galvanic or electrolytic method, it is preferable that the metal compound is at least on the surface of the metal particles in the surface of the counter W object, reduce to metal beforehand. This eliminates any risk of localized deposition due to any leaching of the metal compound from a particular site before it is reduced to free metal which would render such site non-conductive. However, such pretreatment, although very useful, is not necessary. High quality clad articles could also be obtained without such a prior reduction step. As mentioned above, it was surprising to find that the metal compounds could be reduced to metal even below the surface of the coating without affecting the bond between the particles and the elastomeric matrix, thereby reducing the peel strength of the subsequently applied to the surface Metal layer

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was greatly increased. In a standard withdrawal test it was determined that even if the metal is peeled off the plated article, the elastomeric matrix is still solid adheres to the underside of the peeled metal film.

When investigating various binders for the metal compounds, it was surprisingly found that only the polymers known as elastomers gave satisfactory results. Other polymers such as Polycarbonates, polystyrene, polyvinyl chloride, epoxy resins, etc. could be used in the same way to make metal clad Objects are used, but the metallic coating could very easily be removed from the substrate, which is in marked contrast to the high peel strength obtained with the general class of elastomers.

A further improvement in peel strength is obtained by using a solvent, a solvent mixture or a mixture of solvents and non-solvents in order to dissolve those elastomers which can attack the solvent without adversely affecting the substrate on which the composition containing the metal compound is applied is to be applied. If the solvent does not attack the substrate, as is the case, for example, when using ceramic, glass or thermosetting substrates, good adhesion is obtained by roughening the surface, for example by means of a sandblasting blower, by grinding, etc. If maximum adhesion to a substrate is being dispensed with, then the substrate should be of a type such that it is attacked but not adversely affected by the solvent used in the coating composition. In general, the aromatic hydrocarbons and aromatic halogenated hydrocarbons are good solvents for the elastomeric 1,3-butadienes and the strongly polar solvents such as dimethylformamide, dioxane, etc. are good solvents for the elastomeric polyurethanes.

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Monoral acrylonitrile, is an excellent tool, which can be used together with aromatic hydrocarbons to form the elastomeric copolymers of butadiene Dissolve acrylonitrile. These solvents can be diluted with other solvents, the stronger or the weaker one Have solution or even non-solution properties for the elastomer around the desired evaporation rates or to obtain the desired degree of attack of the solvent on a particular substrate. For example, a solution ^ agents that damage a substrate are used in small quantities together with other solvents for the elastomer, that have little or no effect on the substrate.

Examples of elastomers which have been found to be extremely useful are elastomers, the polymers of US Pat Represent 1,3-butadienes. You can make homopolymers or copolymers (graft, block, irregular polymers, etc.) with others be polymerizable monomers. Other suitable classes of elastomers are known in the art as polymeric urethane elastomers, Silicone elastomers, chlorosulfonated polyolefin elastomers, etc. are known.

"Specific examples of elastomers that can be used are polymers of 1,3-butadiene alone or copolymerized with other polymerizable monomers such as styrene, acrylonitrile, butene, etc., natural rubber, polymers including copolymers of 2-chloro-1, 3-butadiene, etc. These polymers are used in their thermoplastic form, that is, they are still soluble in the solvent and are not crosslinked or vulcanized to their insoluble, infusible state, however vulcanizing or curing agents can be incorporated and the compositions later vulcanized or crosslinked .

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The polymeric urethanes are generally the reaction products of a dihydroxy compound and a diisocyanate * In this form they are thermoplastic and easily soluble in a variety of solvents. The commercially available products are generally prepared using a dihydroxy compound which is either a polyester or a polyether having a molecular weight in the range of 500 to 5,000, and are then reacted with the diisocyanate to obtain a high molecular weight polymeric urethane. The inclusion of either a small amount of a hydroxy compound such as glycerol, trimethylolpropane, sorbitol, etc. or a small amount of a polyisocyanate that contains more than two isocyanate groups leads to crosslinking of these polymers and thus to insoluble products. When to ^r manufacture. If it is desired to use such crosslinked products in the compositions containing the metal compound, the crosslinking or curing agent is added to the composition just prior to use and the films, fibers, surface coating, etc. prepared prior to the curing of the composition.

The silicone elastomers can be any of those in U.S. Patent 2,867,603 and the patents listed therein Be French elastomers and be mixed with other elastomers mentioned therein. Unhardened silicone elastomers and mixtures with other elastomers are readily soluble in liquid aromatic hydrocarbons. In the cited patents also mention various hardeners named for these compositions. The preferred silicone elastomers are the polydimethylsiloxane and Polymethylphenylsiloxane elastomers.

The chlorosulfonated polyolefin elastomers can be any that in U.S. Patents 2,416,060 and 2,416 06l mentioned elastomers, which also describe curing processes. Usable blends of these polymers

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with other elastomers, US Pat. No. 2,729,6O8 mentions also processes for curing such compositions. is called. Before curing, the chlorosulfonated polyolefins and the mixtures with other elastomers are easily soluble in liquid aromatic hydrocarbons. The preferred and most readily available chlorosulfonated polyolefin elastomers are the chlorosulfonated polyethylenes. The above-mentioned elastomers as well as other known in the art elastomers for the production of ER- length inventive conductive compositions useful.

It can be seen from what has been stated above that these elastomers must initially be soluble in a suitable solvent, ie they must be elastomers which are soluble in solvent. If the composition is used to produce pressed or shaped objects, then the metal oxides or hydroxides in the elastomer can be dispersed by grinding the elastomer on differential rolls and the metal compound added to the elastomer or by using other mixing devices commonly used in rubber or plastics engineering , such as an internal Banburry mixer. These solid disper- sions W of the metal compound in the elastomer, conventionally by means of extrusion, and pressing process and the procedures are processed for processing into films and laminates into shaped articles.

Shall the compositionune: be used as a color to others To provide objects on the surface with a coating, as well as for wet spinning: of fibers, etc., the dispersion is on most conveniently prepared by first dissolving the elastomer in a suitable solvent. Contains the Solution for whatever reason Gel particles of the elastomer which do not dissolve, the solution is expediently filtered off to remove the gel particles and to ensure

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that they are no longer present in the finished composition. The metal compound is in the solution with the help of Standard methods of paint manufacture for dispersing pigments dispersed in paints, for example with the help of Paint mills j ball mills, rod mills, etc. to ensure that any agglomerates of the powdery Metal compound are dissolved.

For Lehmann it can be seen that the amounts of the elastomer and the metal compound contained in the end products produced from either the solid or liquid dispersions should be kept within certain practical limits. If too much of the metal compound before ₅ is not sufficient, the amount of elastomer to form around the particles of the metal compound into an integral mass or to connect a coherent film or coating on a substrate. The maximum amount of metal compound,, which can be incorporated, cannot simply be stated in percentages, since it depends on the particle size, the nature of the binder, etc. As a general guideline, rather than a strict limit, it is understood that the metal compound should generally not exceed 60% by volume of the total volume of the solids content of the composition in order for good results to be obtained. The critical limit, however, is determined by the amount of elastomer that is necessary to give the composition a coherent film-forming properties, that is, that the solid dispersion is processed into a coherent sheet or film and the liquid dispersion by pouring, spraying, coating, etc. can be processed to form a coherent film or coating.

Obviously, the electrical conductivity after the reduction is adversely affected if the amount of the metal compound is too small, i.e. the amount of the elastomer is so large that that the individual metal particles in the elastomer base

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are completely enveloped. The minimum amount of in the elastomer The dispersed metal compound is best expressed as the amount sufficient to make one out of such Composition of the film produced can be electrochemically reduced to the metal. The percentage required is fluctuating and is in turn dependent on the particle size, the nature of the binder, the degree of dispersion, the Thickness of the coating, etc.. Coatings that are 0.002 mm (0.1 mil) or less thick take much longer

™ to be electrochemically reduced or plated as Coatings that are at least 0.02 mm (1 mil) thick. Should be as a general guideline rather than a strict limit apply that the amount of metal compound should be at least 20 vol. # of the pesticides in the composition, if yet another conductive substance such as conductive carbon, semi-conductive copper oxide, molybdenum dioxide etc. is present and at least 25 vol. $ if no other conductive solid is present in the composition. In general, if the metal compound is present in less than these amounts, the reduction ° deposition goes like this slowly in front of you that any savings in the metal

| Connection by the cost of longer proceedings and when using electrochemical means are compensated by inefficiency. Are for the one containing the reduced metal The metal compound should have the highest conductivity and require optimal properties for the deposited metal film in amounts of 30 to 50 Vol.Ji and the elastomer in Quantities between 70 to 50 vol. $ Are available.

The oxides and hydroxides of indium, cadmium, lead and zinc are readily available in powder form and have a particle size on the order of 1 to 2 µm or smaller. The smaller the particle size, the more evenly the metal coating will be applied to the conductive layer. If a mirror-like surface finish is required, this can easily be done by using particle sizes in

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of the order of 1 to 2 to be achieved. Will be a If a matt surface finish is required, particle sizes of up to 10 μm can be used, with rougher surfaces being due larger particle sizes can be obtained.

After the metal compound is dispersed, the mixtures are used to make up any intended non-conductive Substrates by applying techniques such as spraying, dipping, brushing, treatment with Rolling, sieving with silk, etc., to be superficially covered in order to either cover the entire surface or only certain intended ones To cover surfaces with a coating. Before use hardening agents can be added to the elastomer, see above. that the coating becomes insoluble and infusible can be cured or vulcanized. Optionally, the solutions of the polymers can be prepared by wet spinning processes are spun to produce fibers.

The solution can be poured onto a well-polished metal band and results in films that after evaporation of the liquid can be peeled off to form self-supporting films. If the metal compound is cadmium oxide or indium oxide, you can the films, fibers or surface coatings are used where a semi-conductive surface is desired, for example with corona shutters to dissipate static charges, etc. The solid dispersions can with the help of any known Process are brought into the intended form.

As already stated, the objects can be introduced directly into an electroplating bath _; to obtain a metal plated article having high conductivity; however, the metal compound is preferably cathodically reduced beforehand, as described above, and results in a surface with high conductivity which can be used as such, for example as a heating element, etc., as an electrical conductor or as a base on which another metal can be deposited, to either corrugated objects

ORIGINAL INSPECTED

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To design jewelry or use surfaces made of metal. Is a metal surface either by electrodeposition or Once non-electrodeposition processes are obtained, one or more additional metals can optionally be deposited on top of this Metal to be deposited. The conductive fibers obtained in this way can either be before or after the deposition of a metal can be spun into fabrics etc. The aspects of the present invention outlined above are made possible by the Drawing illustrates.

Fig. 1 shows an embodiment of the present invention which a decorative pattern such as a letter is formed on a non-conductive substrate. In the preparation of of the pattern, the non-conductive substrate with the polymer filled with the metal compound and described here can only be coated on the surfaces on which the metal is to be deposited later. If necessary, a larger area can be coated and reduced and then masked, so that the deposited metal is only in the desired places is deposited. The latter procedure leaves part of the conductive polymer surface free of the deposited metal. For producing an electrical circuit such as a printed circuit board using the method of the invention it would not be useful in general! an unplated conductive one To have interconnection from the polymeric coating shorting out the metal plated circle. Sin procedure the use of both unplated and plated conductive circles can be used to tell the difference in terms of conductivity, for example, to be used in a shunt connection.

Instead of applying a pattern, the entire free surface of an object such as a button, a handle, a fiber, a rod, etc. can be coated with the metal and optionally with one or more other metals such as silver, nickel, chromium. Gold. Platinum _: zinc,

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- 21 brass, cobalt, etc. to be plated.

FIGS. 2 and 3 show certain embodiments of the present invention Invention: as described above. In these figures the thickness of the layers is for the purpose of illustration greatly increased.

Fig. 2 shows the coating -that is filled with the metal compound and applied to a selected part of the surface of a substrate having electrically insulating properties, i.e. represents a non-conductive base element. the actual area covered by the coating can be any desired area for simple or difficult patterns to be obtained will. It can be used as such as an electrical circuit on the insulating part or coated with a metal, as Fig. 3 shows, form decorative or useful patterns such as printed circuit boards

The following embodiments are intended to complete the present invention explain in more detail.

example 1

This example shows the variability of conductivity by changing the amount of metal compound _; which is embedded in the polymer matrix. A solution of a polymeric 2-chloro-1,3-butadiene was prepared, which will hereinafter be referred to as chloroprene elastomer (neoprene AD-IO) and contains 50% heptane, 25 % toluene, 15 % by volume Contains benzene and 10 vol. $ Monochlorobenzene. The fastest way to dissolve was by dissolving the elastomer in the aromatic components of the solvent mixture and then adding the heptane. This solution was used as a stock solution and cadmium oxide with an average particle size of 1 µm was added in amounts sufficient to obtain dispersions based on the total volume of the metal oxide and

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of the elastomer, 20, 25, 30, 35, 40, 50 and 60 vol. 5? Cadmium oxide contained and then with the help of a ball mill a

gave a homogeneous dispersion. The surface of one side of a transparent test plate of 5 × 7-5 × 0.31 cm (2 × 3 × 1/8 inch) pressed from a polycarbonate resin (Lexan) was evenly coated with these dispersions. When dry, the coatings were about 0.02 mm (1 mil) thick. Measurements showed that no significant difference existed in the conductivity of the coatings, at least 40 by volume. ^ ^C ^ n ⁿ¹ held. In contrast, a decrease was found for smaller quantities. The conductivity of the 20 and 25 vol. Coatings containing% cadmium oxide were too low to be measured with an ohmmeter.

Each of these plates was used as a cathode in an aqueous potassium hydroxide solution (10 g / l) and the electrical connection was made with the aid of a clamp on one edge of the coating. The samples were immersed in the electrolyte bath with the lower end of the clamp just touching the surface of the electrolyte. A potential of 2.5 to 3 volts was applied, which resulted in the formation of gas bubbles on the clamp. As a result of the reducing effect that takes place, the ψ nature of the cathode changes and causes a decrease in potential. To compensate for this, the potential was adjusted so that it remained essentially constant throughout the reduction process. The reduction of the cadmium oxide to the metallic cadmium occurred initially at the clip and slowly spread over and into the entire coating at a rate which was dependent on the metal oxide content of the coating. This could be seen because the brown color of the coating, which originates from the cadmium oxide, turned gray with the reduction to the metal.

Coatings containing at least 40 vol. 16 cadmium oxide were used over the entire area of approximately 38 cm (6 sq.inches) over the course of 30 min. Reduced. 25 vol. £ cadmium oxide-containing coatings

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required one night to reduce. The 20 volume # cadmium oxide-containing coating was only about 6 cm (1 sq.inch) reduced after 16 hours. Although the cadmium oxide in such a coating can be reduced to metal, the cost of electricity exceeds the cost of the additional cadmium oxide required. Conductivity measurements showed that the reduced film, which initially contained 40 vol./ί cadmium, was essentially the same as that which contained a larger amount, but decreased below this amount. Surprisingly, it was found that the initially only 25 vol. % Cadmium oxide The film containing hardly any conductivity even after the reduction. However, like the coatings which initially contained large amounts of cadmium oxide, it became readily coated with copper. .

The plating of the coatings with copper took place in that an initial copper layer of about 0.002 mm (0.1 mil) copper was applied in a standard alkaline copper cyanide solution and then plating using a commercially available acidic, light-colored copper plating solution of about 0.05 mm (2 mils) was plated, leaving mirror-like coatings of copper on the polycarbonate sheets became. All of these copper coatings were firmly adherent and could only be removed from the plate by tearing the chloroprene coating are detached and showed that the adhesive strength of the elastomer to the substrate and the adhesive strength of the Elastomers on the copper plating was stronger than the cohesive force of the elastomer. The one used to peel off the copper coating the force required of the coating composition originally containing 60 v / o cadmium oxide was not as great as the force required to peel off the coatings containing a minor amount of the metal oxide, what showed that the higher loading of metal oxide had reduced the cohesive force of the coating layer. Considering the results obtained for conductivity and peel strength clearly show that by using a load of the elastomer with a metal compound, diiybis

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Vol.jS exceeds j no advantage is obtained since the best Results in this range can be obtained and less metal compound must be used.

As the experiment using 20% cadmium oxide with the modification that the composition also contained 2.2 vol. SS of a conductive carbon black was repeated, results were obtained received that were similar to those obtained when using 25 Vol.5? Cadmium oxide had been obtained. this applies A also in the case where copper oxide and lead sulfide were used instead of carbon black.

In all of the above tests, peel strength was determined using a tensile strength meter with a slide speed of 12.5 cm (5 inches) per minute. A strip 2.5 cm wide and 7.5 cm long was cut off with the aid of a razor blade. One end was lifted off with the razor blade so that it could be attached to the gripping jaws. All plated samples gave peel strengths of about 0.62 to 1.11 kg / m (5-9 lbs. per inch). 12stündiges by heating the plated sample at 80 C, even higher peel strengths were ER- keep w, the 1.24 kg / m (10 pounds per inch) exceeded.

Example 2

This example shows that as a binder for the metal compound an elastomer must be used. The following solutions were prepared so that each 10 g of the above Polymer contained in 100 ml of a solvent. After dissolution was achieved, sufficient amounts were powdered Cadmium oxide with an average particle diameter of 1 µm dispersed in the solution and a 40% dispersion of Cadmium oxide, based on the total volume of polymer and des Obtained metal oxide. The compositions are shown in the table below.

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'Table I.

19104AS

Composition of polymer

Solvent (volume ratios)

Polyurethane elastomer (a)

Polyester (b) polycarbonate (c) polyvinyl chloride polyvinyl acetate

Epoxy resin (d) ethyl hydroxyethyl cellulose

Butyl rubber

(a) polyisobutylene

(b) butadiene-isobutylene copolymer

Butadiene Acrylonitrile Rubber Silicone Elastomer

Oil-sulphonated polyethylene elastomer

Dioxane

Dioxane 1,1,2-trichloroethane methyl ethyl ketone

Methy1-ethyl-ketone-toluene (1: 1)

Toluene-n-butanol (2: 3)

Ligroin isopropanol (95: 5)

Chlorobenzene heptane

(20:80) for both

Toluene xylene

toluene

(a) Polyester of 1,4-butanediol and adipic acid, chain-extended with 4.4 ^l -diphenylmethane diisocyanate (Estane 5740 X 1).

(b) neopentyl glycol 4,4'-isopropylidene bisphenol adipate.

(c) 4,4-isopropylidene bisphenol carbonate

(d) Polyamide of a dibasic acid and a polyamine reacted with the reaction product of epichlorohydrin and an epoxy-terminated bisphenol (Epon 1001 - Versamid 100).

(e) The reduction step requires a stirred, neutral electrolyte.

Each of these compositions was used to make a polycarbonate sheet to be coated as in Example 1. After electrochemical reduction of the cadmium oxide to the cadmium metal in

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the coatings and the electroplating with copper only compositions A, H, I, J and K firmly adhered coatings of the clad metal. In all other cases it was peeled the copper metal from the substrate very easily and showed that an elastomeric material is necessary to ensure good adhesion To obtain coatings.

Example 3

Four compositions were prepared similar to Composition A in Example 2, except that the cadmium oxide was replaced with conductive carbon black, cupric oxide, lead sulfide and indium oxide. Since the chemical reduction reaction would be of no use in the case of carbon soot, the chemical reduction was only applied to the other coatings. Of these, only the indium oxide coating containing was slightly reduced to the metal. All of the coatings could be plated with copper to a satisfactory degree, but the coatings containing carbon black, cupric oxide and lead sulfide began to plating at the electrical connector and spread over the surface of the film from there, whereas initially the indium oxide-containing film was immediately plated over the entire surface after the reduction. The copper plating was easily peeled off the samples in which the initial coating contained the conductive carbon, cupric oxide and lead sulfide, in marked contrast to the adherent copper coating that was obtained on the coating, which was initially indium oxide contained.

Attempts to use either V ₃ O ₃ or TigOg, both of which have metallic conductivity, in the above compositions showed that they could not be electrochemically reduced to metal and could not be plated with copper.

Example 4

This example shows the inclusion of a curing agent for the elastomer in a coating composition. By dissolving A solution was prepared from 100 g of chloroprene elastomers in 650 g of toluene and then 4 g of magnesium oxide,

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5 g zinc oxide, 2 g phenyl-beta-naphthylamine and 542 g cadmium oxide dispersed. After these ingredients were well dispersed, a slurry of 10 g of black lead in 10 g of toluene was added to obtain a composition which could be vulcanized by heating. This composition was used to coat a polycarbonate sheet. It was reduced and plated with copper as in Example 1. Heating at 80 ° C overnight led to the vulcanization of the Chloroprene elastomers. The peel strength was 0.86 kg / m (7 lbs. Per inch). It was later found that there was no storage a vulcanizing agent even the cadmium oxide or metal apparently the hardening of the chloroprene polymer after heating had caused, because after a peeling test in which a break occurred in the elastomer body (cohesive break)., the polymer was found not to dissolve in solvents in which the chloroprene elastomer was initially soluble dissolved.

Example 5

Substrates other than the polycarbonates have become successful using the compositions shown in the examples above plated with copper. Examples of different substrates and the respective solvents and elastomers used to make them the dispersions of the metal compound used in elastomers are listed in Table II.

Table II

Substrate elastomeric solvent

Poly (2,6-dimethyl-1,4-chloroprene chlorobenzene phenylene oxide)

Poly (1,4-phenylene sulfone) polyurethane dioxane

Acrylonitrile butadiene (a) chloroprene toluene

Styrene ter- ^ polymer (ABS) (b) Polyuaethane Dioxane

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Polystyrene (a) Chloroprene like solvent

as in example 1

(b) butadiene-toluene
Acrylonitrile copolymer

Mixture of poly (2,6-dimethyl-chloroprene, solvent 1,4-phenylene oxide) and poly as in Example 1

styrene

Phenol-formaldehyde foil chloroprene gl. Solvent

as in example 1

Polymethyl methacrylate Chloroprene gl. Solvent

as in example 1

Example 6

Test plates made of polycarbonate were with a 0.025 mm
(1 mil) thick coating of the following spreads,
where those listed in columns A and B of Table III
Percentages are to be understood as% by weight.

Table III

AWAY

30.75 Cadmium oxide 0.73 Carbon black 7.25 Chloroprene elastomer -_— Butadiene-acrylonitrile rubber
(Hycar 1022) Xylene 11.12 toluene Acrylonitrile 13.18 benzene 8.50 Monochlorobenzene 28.47 Cyclohexane

41.06 0.94

8.00 46.24

3.76

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When these coatings were introduced into the alkaline copper cyanide bath as a cathode without reduction, it could be observed that that the brown color of the coating turned gray, and then the deposition of copper began at the point of electrical contact and then spread outwards in a circle until the whole surface was covered with copper. An inspection from the back showed that the brown color of the coating was now gray with some copper color also showing, showing that the copper plating was in the Elastomer coating had penetrated. This is also to be observed, but to a lesser extent, in the case of coatings that were made before Plating had been reduced. The penetration of the deposited metal also depends on the speed the deposition. Lower deposition speeds result in deeper penetration.

Example 7

This example shows that the use of the metal compound and subsequent reduction before plating leads to a completely different result than when using the free one Metal is started. Two glass plates were coated with a solution of a chloroprene elastomer in xylene, which are referenced on the total volume of the elastomer and the oxide, 40% by volume Contained cadmium oxide. After the metal oxide had been reduced to metal, a coating was peeled off the plate with xylene and used the dispersion to recoat the glass plate. When these two coatings were plated with copper, the reformed coating could not be plated, whereas the other could be plated very easily with an adherent coating was plated from copper.

Two polycarbonate sheets were coated with the cadmium oxide dispersion described above. The one was on the above way described reduced. Both plates were immersed in an electroless copper plating solution (alkaline Copper sulfate tartrate complex formaldehyde solution). Of the

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Reduced plating immediately began to be plated with copper. The other coating was plated with copper after standing overnight. Both copper plates adhered very firmly to the substrate.

Example 8

Various coating compositions made from zinc oxide-chloroprene elastomers were on an acrylonitrile-butadiene-styrene terpolymer (ABS) and on polystyrene substrates (PS) with high impact resistance After drying, the zinc oxide was applied electrochemically reduced in the manner described above and the surfaces obtained from a non-galvanic copper bath covered with copper. Other test panels coated with the last two compositions of Table IV, were also coated with copper after electroreduction using a copper cyanide galvanizing bath. Between there was no noticeable difference between the two methods. The initial copper layers were in a light, clean Copper bath further galvanized in order to obtain a sufficiently thick metal layer for the determinations of the peel strength. The compositions and results are shown in Table IV.

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- 31 Table IV

Composition of the coating (parts by weight)

Zinc oxide chloroprene solvent substrate peel strength, Elastomer kg / m lbs./inch

ABS 0.75 6.1

PS 1.04 8.4

ιοο, ο 32.0 toluene 168.0 benzene 70.2 100, ^{op cit} 26.8 toluene 59.1 acetone 72.1 n-heptane 62.3 ioo, o ^b 26.8 toluene 46.4 acetone 35.4 n-heptane 61.1 1,4-dioxane 46.3 ioo, o ^c 26.9 toluene 211.1 ioo, o ^c 26.9 toluene 211.1 benzene 67.6

ABS 1.15 9.3

ABS 0.63 5.1 ABS 0.75 6.2

a) Commercially available ZnO of unknown particle size

b) Commercially available ZnO; Particle size 0.20 / ura.

c) Commercially available ZnO; Particle size 0.14 µm.

d) Average value from different determinations.

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Example 9

A coating composition containing 100.0 g of zinc hydroxide, 60 ₃ O g of chloroprene elastomer and 600.0 g of toluene was _{applied 3 to} a substrate made of ABS. This experimental plate was electrochemically reduced and plated as in Example 8. A very well adhering copper coating similar to that obtained with ZnO was obtained.

Example 10

With the aid of a ball mill, 100.0 g of lead oxide (black lead) were dispersed in a solution of 15.8 g of chloroprene elastomer in 16.0 g of toluene. After applying this composition
onto an ABS substrate and evaporating the solvent, the lead oxide was electrochemically reduced and plated as in Example 8. The peeling strength was greater than 0.62 kg / m
(5 lbs./inch).

Other metals became lightly on the copper plating of the above Examples are plated, such as nickel, nickel and then chromium, lead, etc. or on the conductive coatings plated directly on.

In general, the plague was made that at the
Manufacture of conductive coatings that are either used as such or as a base for the deposition of a
As metal should serve that the coating should be strong enough that it is opaque to shining light. this
can be easily determined by using a transparent substrate. In general, the coatings for these uses should be at least 0.012 mm (0.5 mil) thick.

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It must be remembered that the volume measures of the amounts of the metal oxide or hydroxide and the elastomer are more important than the weight ratios. The correct weight ratios of the metal compound can be estimated to the elastomer ^men Kus to the numbers in the examples by the densities of the materials are used for calculating the weight of the materials required. In this connection it must be remembered that the density is the real density and not the apparent density, which depends on the extent to which the particles are divided.

The procedures in the above examples are not limited to the precise details given therein. It is also possible to use other elastomeric binders and the other metal hydroxides specified in more detail than those specifically mentioned in the examples, just as other substrates can also be used if the appropriate attention is paid to the choice of solvent from the known properties of the resistance of each selected substrate versus the solvent and the solubility properties of the elastomer selected in each case. Metals other than copper can be applied either as the first metal to be deposited or as additional plating on the first applied metal. The walls of holes drilled through a metal-clad foil can be coated with the compositions of the invention. The metal cladding on the foil provides an easy way to provide each hole with electrical contact and to reduce the metal connection in the plating to metal, even if the metal cladding is masked or not, and then to plate the walls of the holes, preferably after the _e Verki was masked idung to pass establish an electrical connection to the two metal surfaces through the holes.

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Claims (18)

PATENT CLAIMS .1 / coating compound made of an elastomer thereby
characterized as being a metal compound
contains dispersed that consists of the oxides and hydroxides of cadmium, indium, zinc and lead (II) and their mixtures
existing group is selected and the amount of elastomer
sufficient to give the mass the properties for the formation of a coherent film and the amount of the metal compound
sufficient that the metal compound in one of this mass
produced film can be electrochemically reduced to metal 2. Coating composition according to claim I ₃ , characterized in that the metal compound is cadmium oxide. 3. Coating composition according to claim 1, characterized in that the metal compound is zinc oxide. 4. Coating composition according to claim 1, characterized in that that the metal compound is zinc hydroxide. 5. Coating composition according to claim 1, characterized in that that the elastomer contains a polymer of a 1,3-butadiene. 6. coating composition according to claim 1, characterized in that that the elastomer is a polymer of 2-chloro-1,3-butadiene contains. 7. Coating composition according to claim 1, characterized in that the elastomer is a polymeric urethane
contains. 8. Coating composition according to claim 1, characterized in that the elastomer is a silicone elastomer
contains. 909848/1125 1910-5 9. coating composition according to claim 1, characterized indicates that the elastomer contains a chlorosulfonated polyolefin elastomer. 10. Coating composition according to claim 1, characterized in that the elastomer is a chlorosulfonated Contains polyethylene elastomer. 11. Use of the coating composition according to claims 1-10 for partially or completely covering the surface a substrate having electrically insulating properties. 12. Use of the coating composition according to claims 1-10 for partially or completely covering the surface a substrate exhibiting electrically insulating properties, wherein at least the surface of the powdered metal compound in the surface of the firmly adhering coating is reduced to metal. 13. Use of the coating composition according to claims 1 -10 for partially or completely covering the surface a substrate having electrically insulating properties, at least the surface of the powdery Metal compound in the surface of the firmly adhering coating is reduced to the metal, and at least one metal is firmly adhering is electroplated or non-electroplated on the surface of the firmly adhering coating. I ¹ K composition, characterized in that a substrate with electrically insulating properties has a firmly adhering coating of the coating material according to claims 1-10 on at least part of its surface. 15 · Composition according to claim 14, characterized in that - 909848/1125 indicates that at least the surface of the powdered metal compound in the surface of the firmly adhering Coating is reduced to the metal. 16. Composition according to claim 5> characterized in that at least one metal is firmly plated on the surface of the firmly adhering coating. 17. A method for producing a metallic coating on an electrically non-conductive substrate, thereby characterized in that at least a part of the surface of the non-conductive substrate with the coating composition according to claim 1 to 10 coated, at least the surface the powdery metal compound on the surface of the coating is reduced to metal and then at least another metal on the metal in which the coating is plated. 18. The method according to claim 20, characterized in that that the metal is electroplated. 19 · The method according to claim 21, characterized in that that the metal is not electroplated. 909848/1125