Metalization of surfaces

Abstract

There is disclosed a method for application of a metal on a substrate, comprising the steps of a) providing the substrate which comprises abstractable hydrogen atoms and / or C=C bonds, b) producing a covalently bound negatively charged polymer on the substrate, by a reaction between the surface groups and monomers, wherein chain propagation of a growing polymer chain is carried out to the desired extent, wherein step b) is carried out in an environment with no more than 2 wt% water present, c) contacting the substrate with metal ions, d) reducing the metal ions to metal, and e) depositing further metal on the metal. An advantage is both improved adhesion and that a range of different ions such as copper ions can be used in the process.

Description

[0001] Metalization of surfaces

[0002] Technical field

[0003] The present invention relates generally to a method of applying a metal on a substrate surface by a method involving metal ions.

[0004] Background

[0005] In the prior art many different methods of applying a metal on a substrate surface are described, including polymeric substrates .

[0006] WO 2007 / 116056 discloses a method for applying a first metal on paper, which method comprises the steps a) producing polymers on the surface of said paper, said polymers comprising carboxyl groups and adsorbed ions of at least one second metal, said ions being adsorbed at a pH above 7, b) reducing said ions to the second metal and c) depositing said first metal on the reduced ions of said second metal. The ions are selected from ruthenium, rhodium, palladium, osmium, iridium, platinum and copper. In all examples palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0007] WO 2007 / 116057 discloses a method for applying a first metal on a substrate, which method comprises the steps a) producing polymers on the surface of said substrate, said polymers comprising carboxyl groups and adsorbed ions of at least one second metal, said ions being adsorbed at a pH above 7, b) reducing said ions to the second metal and c) depositing said first metal on the reduced ions of said second metal. The ions are selected from ruthenium, rhodium, palladium, osmium, iridium, platinum and copper. In all examples palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0008] WO 2012 / 066018 discloses a method for applying a metal on a substrate comprises: a) applying a coating by treatment in a plasma, comprising a compound selected from alkanes up to 1 0 carbon atoms, and unsaturated monomers, and b 1 ) producing polymers on the surface of said substrate, said polymers comprising carboxyl groups and adsorbed ions of a second metal, reducing said ions to the second metal, or alternatively b2) producing polymers on the surface, bringing the surface of said substrate in contact with a dispersion of colloidal metal particles of at least one second metal, and c) depositing said first metal on said second metal. In all examples palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added. In the general description it is described that ions of ruthenium, rhodium, palladium, osmium, iridium, platinum and copper can be used for the first deposition.

[0009] WO 2013 / 167598 discloses a process for application of metal on a substrate surface comprises applying a mixture of a solvent, a polymerizable monomer, and a photoinitiator on a substrate surface, wherein the photoinitiator does not form two phases together with the monomer and the solvent, i.e. it forms an amorphous mixture without any crystals. The monomer is able to polymerize to a polymer comprising at least one carboxyl group. There after the solvent is evaporated. Polymerization is induced by irradiating the applied dried mixture. Ions are applied and reduced to metal and there after further metal can be deposited. Palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added. WO 2014 / 086844 discloses a method for application of a metal on a cavity filter comprising contacting at least a part of said cavity filter base with a mixture, and inducing a polymerization reaction by exposure to at least one selected from heat and actinic radiation adapted to said at least one initiator to form polymers on at least the inner surface of said cavity filter base, said polymers comprising at least one charged group, and said polymers forming covalent bonds after reaction with at least one selected from an abstractable hydrogen atom and an unsaturation on said cavity filter base, and subsequently applying further metal. Palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0010] WO 2015 / 165874 discloses a method of metallizing a substrate with abstractable hydrogen atoms and / or unsaturations on the surface, comprising the steps: a) contacting the substrate with a polymerizable unit, at least one initiator which can be activated by both heat and actinic radiation, and optionally at least one solvent, b) inducing a polymerization reaction c) depositing a second metal on an already applied first metal to obtain a metal coating. A first metal is added as ions and / or small metal particles during the process. Palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0011] WO 2015 / 165875 discloses a method for application of a metal on a substrate, comprising the steps: a) contacting at least a part of the surface of the substrate with at least one selected from: i) at least one initiator, and a polymerizable unit with the ability to undergo a chemical reaction to form a polymer, said polymer comprising at least one charged group, and ii) a polymer comprising at least one charged group. The contacting is achieved by contacting a pad with a plate comprising the at least one substance and subsequently contacting the pad with the surface of the substrate, thereby transferring the at least one substance to the surface of the substrate. Subsequently a metal layer is produced on the surface. Palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0012] WO 2022 / 018278 discloses a method for treating a surface comprising heating the object and the object with a solution comprising a thermal initiator and a polymerizable molecule, wherein the polymerizable molecule reacts with the surface and forms a covalent bond and optionally a covalently bound polymer on the surface of the object. Metal ions are bound to the surface to make the surface capable of supporting the addition further metal. Palladium ions are bound to the surface and reduced to elemental palladium and there after other metals such as copper are added.

[0013] ABS Polymer Electroless Plating through a One-Step Poly (acrylic acid) Covalent Grafting by Alexandre Garcia, Thomas Berthelot, Pascal Viel, Alice Mesnage, Pascale Jegou, Fabien Nekelson, Sebastien Roussel, and Serge Palacin in ACS Applied Materials & Interfaces 2010 2 (4) , 1177-1183 (DOI: 10.1021 / aml 000163 ) discloses a method for electroless plating of ABS polymers. Poly (acrylic acid) is grafted onto ABS and then Cu-ions are adsorbed to the surface, where after nickel or copper is added using standard methods. It should be noted that the polymer grafted to the surface is first polymerized and then attached covalently to the surface. Even if the article claims excellent adhesion there is still room for an improvement of the adhesion, using this technology.

[0014] In the prior art including the above mentioned applications WO 2007 / 116056, WO 2007 / 116057, WO 2012 / 066018, WO 2013 / 167598, WO 2014 / 086844, WO 2015 / 165874, WO 2015 / 165875, WO 2022 / 018278 palladium is the standard to use in this context. Other metal ions such as copper would be highly desirable to use instead of palladium. For instance, palladium is currently at least 5000 times more expensive compared to copper. Further, palladium can cause health conditions in the working place environment. Nevertheless, the much more expensive palladium is still used in spite of the high cost. Even if WO 2007 / 116056, WO 2007 / 116057, WO 2012 / 066018 mention copper ions together with a number of other metal ions, all examples are conducted with palladium and palladium is the only ion which have proven to work using this technology. Palladium ions are the standard ions to use in the art.

[0015] It is desirable to provide a method for metallization of polymeric substrates, which provides excellent adhesion and allows use of other metal ions than palladium.

[0016] Summary

[0017] It is an object of the present invention to obviate at least some of the problems in the prior art and provide an improved metallized substrate as well as an improved method of metallizing a substrate.

[0018] In a first aspect there is provided a method for application of a metal on a substrate, said method comprising the steps: a) providing the substrate where a surface of the substrate comprises surf ace-groups , wherein the surf ace-groups are at least one selected from the group consisting of abstractable hydrogen atoms and C=C bonds, b) producing a polymer, which is covalently bound to the surface of the substrate, wherein the polymer comprises at least one chemical group, which, in contact with water, is negatively charged, by a reaction between the surface groups and monomers, to obtain the polymer covalently bound to the surface of the substrate, wherein step b) is carried out in an environment with no more than 2 wt% water present, c) contacting at least a part of the surface of the substrate with metal ions after step b) , wherein the metal ions are in an agueous environment, d) reducing the metal ions to metal, e) depositing further metal on the metal.

[0019] In a second aspect there is provided a metallized substrate manufactured according to the method as described above.

[0020] Advantages of the invention include that a wide variety of metal ions can be used instead of palladium, and still give excellent adhesion. In particular, less expensive copper ions can be used. A freedom of selecting the metal ions for the first adsorption is achieved. Further it is possible to obtain a metal layer with only one type of metal atoms, i.e. copper ions .

[0021] Further, the adhesion is excellent not least because the polymerization reaction conducted on the surface of the substrate gives a high number of covalent bonds to the substrate surface, which in turn gives improved adhesion.

[0022] Brief description of the drawings

[0023] Figure 1 shows photographs of plated samples with stripes subjected to peel strength test. Samples a-c from left to right. Sample a and c of grey ABS and sample b made of LG HI 121. Fig 2 shows a flow chart for the method according to the invention .

[0024] Detailed description

[0025] Before the invention is disclosed and described in detail, it is to be understood that this invention is not limited to particular compounds, configurations, method steps, substrates, and materials disclosed herein as such compounds, configurations, method steps, substrates, and materials may vary somewhat. It is also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present invention is limited only by the appended claims.

[0026] It must be noted that, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise .

[0027] As used herein, abstractable hydrogen atoms are hydrogen atoms in a compound, which hydrogen atoms can participate in a chemical reaction, which involves the formation of a new covalent bond. Abstractable in the present invention refers to a reaction when the polymer is covalently bound to the surface of the substrate. If hydrogen atoms in the substrate can participate in a chemical reaction so that a covalently bonded polymer is formed, then it is an abstractable hydrogen.

[0028] As used herein, monomers are molecules, which can undergo polymerization, thereby provide constitutional units to the essential structure of a polymer.

[0029] As used herein, substrate refers to the material or object to be at least partially coated by metal. The substrate refers to the base material on which the method is conducted. As used herein, surf ace-groups refers to chemical groups, which are at the surface of the substrate.

[0030] If nothing else is defined, any terms and scientific terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains.

[0031] ACS Applied Materials & Interfaces 2010 2 (4) , 1177-1183 mentions use of copper ions, but since the polymers are produced first and then grafted onto the surface after the polymerization the adhesion is not as good as for polymers which are polymerized directly on the surface. The latter case gives many more grafting points to the surface and thus a better adhesion. It is also important to note that water is present during the grafting in this article. Thus no water- free environment is disclosed in this article.

[0032] In spite of many attempts to use other ions than palladium ions such experiments have typically failed because an insufficient adhesion has been achieved. Since palladium ions are expensive many attempts to replace palladium have been made, but such attempts have generally not been successful. For instance copper ions have not given sufficient adhesion.

[0033] The inventors have carried out intensive research and have unexpectedly found that other metal ions than palladium ions can be successfully used if the polymers are made by polymerization on the surface in a water-free environment.

[0034] Without wishing to be bound by any particular scientific theory, the inventors believe that the water molecules react with and / or become loosely bound to and / or form a structure around the negatively charged polymers on the surface and that this hampers the subsequent adsorption / binding of many metal ions. Still without wishing to be bound by any particular scientific theory, the inventors believe that water molecules may interfere with the grafting reaction so that it becomes less efficient or at least different compared to the water- free reaction and that this contributes to a lower adhesion when water is present during the grafting.

[0035] When manufacturing the polymers in a water free environment it has been found that the subsequent adsorption of metal ions is much more efficient.

[0036] In the first aspect there is provided a method for application of a metal on a substrate, said method comprising the steps: a) providing 201 the substrate where a surface of the substrate comprises surf ace-groups , wherein the surface- groups are at least one selected from the group consisting of abstractable hydrogen atoms and C=C bonds, b) producing 202 a polymer, which is covalently bound to the surface of the substrate, wherein the polymer comprises at least one chemical group, which, in contact with water, is negatively charged, by a reaction between the surface groups and monomers, to obtain the polymer covalently bound to the surface of the substrate, wherein step b) is carried out in an environment with no more than 2 wt% water present, c) contacting 203 at least a part of the surface of the substrate with metal ions after step b) , wherein the metal ions are in an aqueous environment, d) reducing 204 the metal ions to metal, e) depositing 205 further metal on the metal. The substrate or at least the surface of the substrate should comprise chemical groups selected from abstractable hydrogen atoms and C=C bonds. These groups can be present throughout the substrate, but should at least be present on a part of the substrate surface.

[0037] In step b) a polymer is made by letting monomers react with the surface groups so that covalent bonds form. The monomers covalently bound to the surface groups can then be subject to chain polymerization in which the growth of a polymer chain proceeds by reaction (s) between monomer (s) and active site (s) on the polymer chain with regeneration of the active site (s) at the end of each growth step. The extent of the chain polymerization reaction, i.e. the length of the polymers is determined by factors including amount of monomers and the initiation if initiators are present.

[0038] When a chain polymerization reaction is carried out some polymers will be covalently bound to the substrate surface by a reaction with the surface groups. However, some polymerization will inevitably occur above the surface in an applied solution. It is thus recommended to wash the substrate surface at some point after step b) so that formed polymers which are not covalently bound to the surface are washed away. Polymers which are not covalently bound to the substrate and any other remaining compounds on the substrate, which are not covalently bound to the substrate are easily washed away, since the covalently bound polymers adhere firmly to the substrate surface.

[0039] The monomer should be selected so that it can both participate in a reaction with abstractable hydrogen atoms and / or C=C bonds and so that it can participate in a polymerization reaction to form a polymer covalently bound to the substrate surface .

[0040] It is important that step b) is carried out in a water free environment, or at least in an environment with less than 2 wt% water. The environment refers to the atoms and molecules closest to the surface, i.e. a liquid in contact with the substrate surface must not comprise more than 2 wt% water. The few millimetre closest to surface should not comprise more than 2 wt% water. This can be measured by measuring the water content of the 2 mm above the surface. The water content is measured by weight. The same applies to a gas in contact with the substrate surface, such a gas must not comprise more than 2 wt% water. In one embodiment step b) is carried out in an environment with no more than 1.5 wt% water present. In one embodiment step b) is carried out in an environment with no more than 1 wt% water present. In one embodiment step b) is carried out in an environment with no more than 0.5 wt% water present. In one embodiment step b) is carried out in an environment with no more than 0.1 wt% water present. In one embodiment step b) is carried out in an environment with no more than 0.05 wt% water present. In one embodiment step b) is carried out in an environment with no more than 0.01 wt% water present. The water

[0041] In one embodiment the reaction between the surface groups and monomers, to obtain the polymer covalently bound to the surface of the substrate is carried out so that a liquid mixture is applied on the surface. In one embodiment the liquid is applied so that a confluent layer is formed. In alternative embodiments it is possible to apply the liquid in a desired pattern. In one embodiment the liquid is applied to a thickness of less than 500 pm. When the metal ions are added in step c) they are actually added in an aqueous solution. Thus, the limitation regarding the maximum amount of water only applies to step b) . In step c) the metal ions are provided in an aqueous environment. Providing the metal ions in an aqueous environment means that water is present. Typically, the metal ions are provided in a water solution. Optionally water-miscible solvents may be present. In the aqueous environment, the metal ions and groups on the polymers are positively and negatively charged respectively so that they are attracted to each other. During step c) the pH should be adapted so that the chemical groups are negatively charged if the charge is pH dependent. This pH range can easily be adapted to the chemical groups such as carboxyl groups so that they are negatively charged.

[0042] The polymer covalently bound to the substrate surface should be negatively charged when in water, i.e. in an aqueous environment. This can be achieved by using negatively charged monomers, or at least monomers, which in an aqueous solution are negatively charged. Alternatively, it can be achieved by using monomers comprising chemical groups, which can be converted to negative charges by a chemical reaction. In the latter case, the negative charges emerge after a reaction to produce negative charges.

[0043] The polymer comprises at least one chemical group, which, in contact with water, is negatively charged. Such a chemical group is in one embodiment a carboxyl group, which depending on the pH has a negative charge. If the charge of the chemical group is pH dependent the pH should be adjusted so that the charge is negative. Other examples are highly polar groups, which have a slightly negatively charged part. When the monomer or polymer is in the water free environment in step b) , then it is difficult to define a charge for a carboxyl group. Hence, the negative charge is defined when in contact with water. During step b) it may be the case that there is a chemical group present and some water such as 0.1, 0.5 or 1.0 wt% or similar and that small amount of water may interact with the chemical groups so that there may be some kind of charge also during step b) even if this effect is very limited .

[0044] If desired, the polymerization can be made in a pattern on the substrate surface.

[0045] When the substrate surface has been contacted with metal ions and some metal ions have been associated with the oppositely charged polymer, then the metal ions are reduced to metal, i.e. metal in elemental form. This is effectuated with a reducing agent, which creates reducing conditions. Reducing agents and reducing conditions are well known and any suitable reducing agent can be used. In one embodiment sodium borohydride is used in a concentration of 0.1 M in slightly alkali conditions.

[0046] When the negatively charged and covalently bound polymers have been produced on the surface of the substrate, then metal ions are contacted with the substrate surface. This occurs in an aqueous solution. As long as there are metal ions in the water, then the metal ions will be adsorbed to the negatively charged polymers and thus an aqueous solution can be used to deliver the metal ions. Before the metal ions are contacted with the substrate surface no aqueous solution should be added to the substrate surface. Any counter ions to the metal ions can be used.

[0047] If it is desired to make a pattern on the substrate surface, it is possible to contact only a part of the substrate surface with metal ions. When the metal ions have reduced to metal, then further metal can be applied by using well known and established methods for metallization. It is well known to add metal on an existing layer of metal. Any metal can be applied. Step e) , 205, of adding further metal to the already existing metal is in one embodiment performed in more than one step. Step e) is in one embodiment performed using more than one method.

[0048] The method is particularly suitable for applying metal on polymeric substrates. In one embodiment, the substrate provided in step a) comprises at least one polymer.

[0049] In one embodiment, the reaction of the monomers and the surface groups are initiated with an initiator. Also the chain propagation in the chain polymerization may be initiated with the initiator. In one embodiment, at least one initiator is added in step b) and wherein the reaction in step b) is induced by exposure to at least one selected from the group consisting of heat and actinic radiation adapted to said at least one initiator. Also initiators working according to other principles can be added.

[0050] In one embodiment, a solvent is present at least in step b) and wherein the solvent is at least one selected from the group consisting of an alcohol, an ester and an ether. In one embodiment, a solvent is present at least in step b) and wherein the solvent is at least one selected from the group consisting of methanol, ethanol, acetone, ethylene glycol, isopropyl alcohol, ethyl acetate, propanol, and l-methoxy-2- propanol. If a solvent is not present, for instance a water free mixture of monomers and optionally an initiator can be added .

[0051] In one embodiment, the monomers in step b) are selected from the group consisting of methacrylic acid, acrylic acid, ethyl acrylate, 2-hydroxyethyl acrylate, 2-carboxyethyl acrylate and maleic acid.

[0052] In one embodiment, an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of antraguinone, thioxanthone, isopropyl thioxanthone, xanthone, benzophenone, and fluorenone.

[0053] In one embodiment, an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of alpha-hydroxyketone , phenylglycolate, acylphospine oxide, alpha aminoketones, benzildimethylketal, and oxime esters.

[0054] In one embodiment, an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of peroxides, and azo compounds.

[0055] Before the polymerization on the surface, it is possible to treat the substrate surface with various methods. This is particularly suitable for substrates which are known to be difficult to treat or for surfaces which comprise few surface groups (i.e. few abstractable hydrogens and / or few C=C bonds) .

[0056] In one embodiment, an initiator is present together with a synergist. Such a synergist can have the effect of enhancing surface polymerization. As an example, 2-Ethylhexyl 4- dimethylamino benzoate is a tertiary amine synergist typically used in combination with Norrish type II photoinitiators such as benzophenone, thioxanthone, and isopropyl thioxanthone. It is known for its ability to promote surface cure, i.e. to promote polymerization at the substrate surface. It is soluble in most monomers, oligomers and pre-polymers but insoluble in H20, which makes it suitable in a water free system. In one embodiment, a polymerization inhibitor is added in step b) . This is to prevent autopolymerization. For instance, 4- methoxyphenol can be used as a polymerization inhibitor for acrylates. Unsaturated monomers such as acrylates should preferably have inhibitors for both processing and safe transport and storage.

[0057] In one embodiment, ammonia is present at least in step b) . Ammonia forms a complex with the monomers in step b) , in particular with (meth) acrylic acid. (meth) acrylic acid denotes both acrylic acid and / or methacrylic acid.

[0058] In one embodiment, the substrate is treated with at least one selected from the groups consisting of plasma, corona, and flame treatment before step b) .

[0059] In one embodiment, the metal deposited in step e) is at least one selected from the group consisting of copper, silver, nickel and gold. In one embodiment, the metal deposited in step e) is at least one selected from the group consisting of copper, and nickel. In one embodiment, the metal deposited in step e) is copper. It is an advantage that copper can be used both since it is far less expensive than for instance palladium and since the copper can be used for further addition of metal resulting in a substrate which is coated with copper only.

[0060] In the second aspect there is provided a metallized substrate manufactured according to the method as described above.

[0061] Other features and uses of the invention and their associated advantages will be evident to a person skilled in the art upon reading the description and the examples.

[0062] It is to be understood that this invention is not limited to the particular embodiments shown here. The following examples are provided for illustrative purposes and are not intended to limit the scope of the invention since the scope of the present invention is limited by the appended claims.

[0063] Examples

[0064] Example 1

[0065] Copper ions for metallization of surface modified polymers. In this experiment adsorption of copper and nickel ions to surfaces is tested.

[0066] Materials

[0067] Experiments were made on different polymer substrates comprising Acrylonitrile Butadiene Styrene (ABS) . The substrate was an ABS substrate with a grey color.

[0068] For the surface bound polymerization, a mixture of monomers, initiators and solvent were used, see Table 1. Chemicals used for the polymerization mixture were i) anhydrous acrylic acid, 99 wt%, with 200 ppm 4-metoxyphenol and ii) 2-carboxyethyl acrylate, with 1000 ppm 4-methoxyphenol , i.e. they were used as monomers. As initiator isopropyl-9K-thioxanthen-9-one (i.e. an isopropyl thioxanthon) , a mixture of 2- and 4-isomers was used. In the initiator system 2- ethylhexyl (dimethylamino) benzoate was also used as synergist to enhance surface polymerization rate and yield. As main solvent for the polymerization mixture ethanol, 99.7, wt% and l-methoxy-2-propanol , 99.5 wt% , was used. Ammonia, 2 M, dissolved in ethanol and 1 , 2-ethanediol were used as additional components to make up the polymerization mixture. The mixture for the polymerization has less than 1 wt% water in total. Thus, the mixtures and substances to make the polymerization were essentially water free. The mixture of reactants and solvent was applied on the substrates using a commercial spray gun used for various paint applications. The mixture of reactants and solvent was applied so that a confluent layer was formed. To initiate the polymerization a 395 nm UV-LED lamp was used. The power density of the irradiation was 12 W / cmz.

[0069] For metal activation (step 203) of the formed polymer a water solution of 0.1 M copper ( I I ) sul f ate pentahydrate with 1.2 M ammonia or 0.1 M nickel ( II ) sulf ate hexahydrate respectively with 1.2 M ammonia. Reduction of adsorbed metal ions (step

[0070] 204) was done in a water solution of 0.1 M sodium borohydride and 0.1 M sodium hydroxide. Plating of the activated surfaces (step 205) was performed using commercial electroless copper followed by galvanic plating in an acid copper bath. Table 1 Composition of acrylate reaction mixture used for surface bound polymerization.

[0071] Method

[0072] Polymerization Clean plastic samples were sprayed with the grafting mixture creating a thin uniform coating, i.e. a confluent layer. The wet pieces were transferred to the UV-source and exposed to the light for 10 seconds for polymerization of the acrylics on to the substrate surface. To remove polymer that not had bound to the surface, the samples were rinsed in tap water for 5 minutes so that the polymers bound to the surface remained. This gave polymers covalently bound to the substrate surface (step 202) .

[0073] Activation and plating

[0074] Washed and wet samples were immersed in the copper or nickel activation respectively (step 203) and were soaked for 1-10 minutes at ambient temperature. After the soaking, where metal ions adsorbed to the polymer, the samples were quickly rinsed under running tap water. They were then transferred to the reduction solution and treated for 10 minutes at 40 °C under mild agitation of the liquid, (step 204) This was followed by a 5-minute rinse in tap water. The rinsed samples were plated in a formaldehyde electroless copper bath with high activity until a uniform copper coating was achieved, (step 205) The samples were then electroplated with copper to a thickness of about 20 pm to assess adhesion, (step 205) Plated samples were then masked with tape and 6.35 mm strips of copper were etched out on the surface. Peel strength tests were performed on the strips .

[0075] Resul ts

[0076] Both types of ABS and the polyamide were successfully activated with copper, i.e. ions were adsorbed on the oppositely charged covalently bound polymers. After the reduction step a uniform dark grey layer of reduced copper was formed. In the electroless copper plating a somewhat coarse copper deposit was formed on the activated surfaces. Surfaces that had not been covered by the spray coating, and hence had not undergone any surface modification, had no deposit. On the electroless copper deposit both high acid matte galvanic copper and low acid bright galvanic copper could be plated with desired finish. When testing the peel strength, the grey ABS type showed a very good adhesion with about 10 N / cm.

[0077] Table 2 Peel strength values for grey ABS treated in copper activator for 1 or 10 minutes respectively.

[0078] Example 2.

[0079] Same type of materials, method and activation / plating was used as in example 1. The only difference is that Palladium ions was used for metallization of surface modified polymers and aliphatic PUR was used as material to be metallized.

[0080] Different mixtures with and without water were compared.

[0081] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 weight-% on acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0082] The water free grafting solution had the same composition as in example 1.

[0083] The results show that the water free grafting solution is giving higher adhesion values compared to the water grafting solution .

[0084] Example 3.

[0085] Same type of materials, method and activation / plating was used as in example 1. The only difference is that the light source is a Fusion F-300 UV lamp with a H-bulb . The panels were irradiated with an energy of 1200 mJ / cm2(UVA + UVB) .

[0086] The results are shown below:

[0087] The result shows that different type of Actinic light gives similar results for the adhesion.

[0088] Example 4.

[0089] Same type of materials, method and activation / plating was used as in example 1. The only difference is that Nikel ions (Ni2+, Nikel acetate) was used for metallization in combination with Sodium Borhydride (NaBH4) solution as reduction agent. The surface modified polymers and aliphatic PUR was used as material to be metallized.

[0090] Different mixtures with and without water were compared.

[0091] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 23 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 weight-% on acrylic acid) , 60 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0092] The water free grafting solution had the same composition as in example 1.

[0093] The results show that the water free grafting solution is giving higher adhes ion values compared to the water grafting solution .

[0094] Example 5.

[0095] Same type of materials, method and activation / plating was used as in example 1. The only difference was that Palladium ions was used for metallization and various materials were used as material to be metallized.

[0096] Electrode free broad spectrum mercury UV lamps were used. Different mixtures with and without water were compared. Time in activation bath was 10 minutes.

[0097] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 wt% based on the weight of acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0098] Used on substrates made of acrylonitrile butadiene styrene polymer, polyamides, polyethylene terephthalate, polytetrafluorethylene, cyclic olefin copolymers, acrylonitrile styrene acrylate polymer, polyphenylene oxide, polyphenylene ether, polyether imide, and polypropylene.

[0099] Benzophenone 2.0 g

[0100] Ethylene glycol 3.5 ml

[0101] Acrylic acid 13.0 ml

[0102] Ammonia 2M in ethanol 41.0 ml

[0103] 2-hydroxyethyl acrylate 3.0 ml

[0104] The results show that the water free grafting solution is giving higher adhesion values compared to the water grafting solution .

[0105] Example 6.

[0106] Same type of materials, method and activation / plating was used as in example 1. The only difference was that Palladium ions was used for metallization of surface modified polymers and aliphatic PUR was used as material to be metallized.

[0107] An UV-laser at 375 nm was used.

[0108] Different mixtures with and without water were compared. Time in activation bath was 10 minutes.

[0109] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 wt% based on the weight of acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) . Used on substrates made of acrylonitrile butadiene styrene polymer and polyurethane aliphatic polymer.

[0110] Used on substrates made of polyurethane and acrylonitrile butadiene styrene polymer.

[0111] The results show that the water free grafting solution is giving higher adhesion values compared to the water grafting solution .

[0112] Example 7.

[0113] Same type of materials, method and activation / plating was used as in example 1. The only difference is that Palladium ions was used for metallization and various materials were metallized. UV-LED at 365 nm was used.

[0114] Different mixtures with and without water were compared. Time in activation bath was 10 minutes.

[0115] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 wt% based on the weight of acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0116] Used on substrates made of acrylonitrile butadiene styrene polymer, acrylonitrile styrene acrylate polymer, flame resistant epoxy laminates, polyamides, polyphenylene oxide, and polyphenylene ether.

[0117] The results show that the water free grafting solution is giving higher adhesion values compared to the water grafting solution .

[0118] Example 8.

[0119] Same type of materials, method and activation / plating was used as in example 1. The only difference was that Palladium ions was used for metallization. Various materials were metallized. UV-LED at 365 nm was used.

[0120] Different mixtures with and without water were compared. Time in activation bath was 10 minutes.

[0121] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 wt% based on the weight of acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0122] Used on substrates made of acrylonitrile butadiene styrene polymer, polyamides, polyether imide, acrylonitrile styrene acrylate polymer and polypropylene. The results show that the water free grafting solution is giving higher adhesion values compared to the water grafting solution .

[0123] Example 9.

[0124] Same type of materials, method and activation / plating was used as in example 1. The only difference was that Palladium ions was used for metallization. Various materials were metallized. Electrode free broad spectrum mercury UV lamps were used. Different mixtures with and without water were compared. Time in activation bath was 10 minutes.

[0125] The results are shown in table below with comparison of water based grafting solution. The water containing grafting solution has the following recipe: 25 ml acrylic acid, 18 ml Ammonia (30 wt% NH3and 70 wt% water) , thioxanthone (3.2 wt % based on the weight of acrylic acid) , 58 ml ethanol (70 wt% ethanol, 30 wt% water) .

[0126] Composition for padprint applications.

[0127] Used on substrates made of acrylonitrile butadiene styrene polymer and polyamides. The compositions were applied in a pattern with lines using pad-printing.

[0128] The water-free compositions allowed pad-printing of distinct lines .

Claims

Claims :

1. A method for application of a metal on a substrate, said method comprising the steps: a) providing (201) the substrate where a surface of the substrate comprises surf ace-groups , wherein the surface- groups are at least one selected from the group consisting of abstractable hydrogen atoms and C=C bonds, b) producing (202) a polymer, which is covalently bound to the surface of the substrate, wherein the polymer comprises at least one chemical group, which, in contact with water, is negatively charged, by a reaction between the surface groups and monomers, to obtain the polymer covalently bound to the surface of the substrate, wherein step b) is carried out in an environment with no more than 2 wt% water present, c) contacting (203) at least a part of the surface of the substrate with metal ions after step b) , wherein the metal ions are in an aqueous environment, d) reducing (204) the metal ions to metal, e) depositing (205) further metal on the metal.

2. The method according to claim 1, wherein the substrate provided in step a) comprises at least one polymer.

3. The method according to any one of claims 1-2, wherein the substrate comprises at least one polymer comprising a C=C bond.

4. The method according to any one of claims 1-3, wherein at least one initiator is added in step b) and wherein the reaction in step b) is induced by exposure to at least oneselected from the group consisting of heat and actinic radiation adapted to said at least one initiator.

5. The method according to any one of claims 1-4, wherein a solvent is present at least in step b) and wherein the solvent is at least one selected from the group consisting of an alcohol, an ester and an ether.

6. The method according to any one of claims 1-5, wherein a solvent is present at least in step b) and wherein the solvent is at least one selected from the group consisting of methanol, ethanol, acetone, ethylene glycol, isopropyl alcohol, ethyl acetate, propanol, and l-methoxy-2-propanol .

7. The method according to any one of claims 1-6, wherein the monomers in step b) are selected from the group consisting of methacrylic acid, acrylic acid, ethyl acrylate, 2-hydroxyethyl acrylate, 2-carboxyethyl acrylate, and maleic acid.

8. The method according to any one of claims 1-7, wherein an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of antraquinone , thioxanthone, isopropyl thioxanthone, xanthone, benzophenone, and fluorenone.

9. The method according to any one of claims 1-8, wherein an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of alpha-hydroxyketone, phenylglycolate, acylphospine oxide, alpha aminoketones, benzildimethylketal, and oxime esters.

10. The method according to any one of claims 1-9, wherein an initiator is present at least in step b) and the initiator is at least one selected from the group consisting of peroxides, and azo compounds.

11. The method according to any one of claims 4 or 8-10, wherein at an initiator is present together with a synergist.

12. The method according to any one of claims 1-11, wherein a polymerization inhibitor is added in step b) .

13. The method according to any one of claims 1-12, wherein ammonia is present at least in step b) .

14. The method according to any one of claims 1-13, wherein the substrate is treated with at least one selected from the groups consisting of plasma, corona, and flame treatment before step b) .

15. The method according to any one of claims 1-14, wherein the metal deposited in step e) is at least one selected from the group consisting of copper, silver, nickel and gold.

16. The method according to any one of claims 1-15, wherein the metal deposited in step e) is at least one selected from the group consisting of copper, and nickel.

17. The method according to any one of claims 1-16, wherein the metal deposited in step e) is copper.

18. A metallized substrate manufactured according to the method of any one of claims 1-17.

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