PROCESS TO METALIZE A PLASTIC SURFACE
Description
The present invention relates to a process for metallizing a plastic surface. Within the scope of the process, according to the invention, the plastic surface of a plastic article or the plastic surfaces of various plastic articles are metallized. In another aspect, the metallized plastics are used for decorative purposes, for example in the field of sanitary installations or in the manufacture of automobiles. In another aspect, the metallization of plastics also comprises the relation to the treatment of the surface of electronic components for electronic protection purposes. Especially the surfaces of plastics, such as acrylonitrile-butadiene-styrene (ABE) and possibly ABE polycarbonate blends are metallized for decorative purposes. In a process already known in practice, the plastic surface is first roughened by strong etching, for example with chromic acid or with chrome-hydrochloric acid. By rough surface is meant especially, to the process of engraving, micro-carvenas that are created on the surface of the plastic. These micro-caverns, in general, have a size in the order of .1 to 10 μm. Especially these micro-caverns show a depth (for example an extension from the plastic surface towards the interior) in the range of .1 to 10 μm. The engraving is performed at relatively high temperatures, as a rule, for relatively large periods. The concentration of an oxidant that is added to the etching solution is usually relatively high. The roughening of the plastic surface has the purpose of subsequently allowing the activation layer and / or the metal layer to be applied so as to almost bind on the rough plastic surface. The adhesion of a metal layer to the rough plastic surface is achieved almost in the manner of the principle of rapid fixing in this known process. After etching or roughing the plastic surface, first the surface is activated with colloidal palladium or palladium ionogen. This activation, in the case of the colloidal process, is continued by the elimination of a thin protective colloid, or in the case of the ionogenic process, a reduction to elemental palladium. Subsequently, copper or nickel is chemically deposited on the plastic surface as a conductive layer. After this, the galvanization or the process to metallize respectively is carried out, in practice, this direct process to metallize the plastic surface acts only for certain plastics- If the roughness of the plastic is sufficient, or the formation of the micro- Carveras is suitable, respectively, it is not possible that by etching the plastic surface, a functionally secure adhesion of the metal layer to the plastic surface is not guaranteed. Therefore in the case of the known process, especially the number of plastics capable of being coated is widely limited. The direct process for metallizing in accordance with this known process generally only works smoothly with the plastic parts of ABE. In the case of blends of ABE polycarbonate and polypropylene, the process for metallizing is only possible under certain working conditions. In view of this, this known process is capable of being improved. In the case of another known process ("Novel methods of coating by chemical reaction or direct electrodeposition of plastics", A.Vaskelis et al., Institute of Chemistry, A Gostauto 9, 2600 Vilnius, Lithuania, documents presented at INTERFINISH 96 WORLD CRONGRESS , International Convention Center, Mirminghara, England, September 10-12, 1996), the plastic surface is similarly rough, by relatively strong or difficult etching and respectively. Here micro-caverns are also formed on the plastic surface by engraving in which the metal layer to be applied is clamped or mechanically joined. Also the engraving is carried out at elevated temperatures in this process. The solution for recording generally has a high concentration of an oxidant. The plastic surface, pretreated in this manner, subsequently treated with a solution of a copper salt, and then treated with a second solution, containing sulfur ions or polysulfide ions. In this way, an electrically conductive layer of non-stoichiometric copper sulfide is formed on the plastic surface. The initial stage of this known process is continued by the treatment of the plastic surface with both the solutions cited at room temperature for a duration of at most 1 minute. Even with this first stage, only certain plastics can be metallized in a satisfactory and functionally safe way. After a second step of this known process, the treatment with both of the mentioned solutions is carried out at an elevated temperature of 70 to 90 ° C, and for a longer period of 5 to 15 minutes. Within this working process, it will be understood that both the sulfur ions and also the copper ions penetrate the plastic surface in the plastic, and the non-stoichiometric copper sulfide is also generated under the plastic surface.
In this way, especially the good adhesion of the subsequently applied metal layer is also achieved. However, the penetration described is performed only in a very incomplete manner, and therefore the adhesion of the metal layer also leaves something to be desired. In addition, also within this process, only certain plastics can be metallized in a satisfactory manner. In practice, there are also several known processes, whereby after etching the plastic surface and the formation of the micro-caverns, the plastic surface is treated with a solution of a copper salt. Subsequently, the treatment with a sulfur solution is applied. All these processes are characterized by the disadvantage that in order to create a partly satisfactory metal layer, the mentioned process steps must be repeated several times in sequence. It will be understood that this is complex and expensive. In contrast, the invention is based on the technical problem to describe a process of the type mentioned above, by which, in a less complex manner, a large variety of plastics can be metallized in a reproducible and functionally safe manner, thereby they are provided with a metal layer which has all the requirements. To solve this technical problem, the invention describes a process for metallizing a plastic surface, whereby the following stages of the process are performed in sequence: 1.1) The plastic surface is subjected to etching under mild conditions. 1.2) Subsequently, the plastic surface is treated with a solution of the metal salt which comprises at least one salt from the group of "Cobalt salt, silver salt, tin salt, lead salt" 1.3) The surface of Plastic is treated with a sulfur solution. 1.4) Finally, the plastic surface is metallized in a metalizing bath. Additional stages of the process, especially washing steps, can be interspersed with the process steps which are the object of the invention. The gentle engraving to which the invention relates means especially that the "engraving" or treatment of the plastic surface, respectively, with a solution for engraving occurs at low temperatures and / or within a shorter period of time at the concentration low of the burn solution. As a main matter, soft etching conditions can be performed either when one of the three conditions above is performed. The low temperature referred to in this invention means a maximum temperature of 40 ° C. When the mild etching conditions are created by a low temperature, this is using a maximum temperature of 30 ° C, with a temperature between 15 ° C and 25 ° C being preferred. With the aforementioned low temperature, the pre-treatment with the recording solution is carried out especially in a period of time of 3 to 15 minutes, preferably of 5 to 15 minutes, and even more preferred of 5 to 10 minutes. The invention claims that the treatment period is shorter than the highest temperature. However, mild etching conditions can be achieved at temperatures in excess of 40 ° C if the selected treatment period is appropriately short. According to a version of the invention, the engraving treatment is carried out at temperatures of 40 ° C to 95 ° C, preferably 50 ° C to 70 ° C, for a treatment period of 15 seconds to 5 minutes preferably from .5 to 3 minutes. Here, also the invention claims, that the treatment period is the shortest at the highest process temperature. In practical terms, the process temperature and / or the process time is selected according to the type of the recording solution employed. The smooth engraving as specified in the invention also means that, contrary to the known procedure referred to above, a way of roughing the plastic surface, or the creation of the micro-caverns on the plastic surface, respectively does not occur. The micro-caverns created with the engraving according to the state of the art or the hollow spaces, respectively, normally have a diameter or a depth, respectively, in a size in the range of .1 to 10 μm. However, the invention faces that the engraving conditions are adjusted so that only small openings or pores, respectively, are created on the plastic surface which have a diameter and especially a depth of <; .09μm, with < .05 μm preferred. In this relation, the depth means the degree of the openings / accesses of the plastic surface inside the plastic. Therefore, without the engraving in the classical sense is performed in the present as is the case with the known process. The invention comprises that by creating small openings or pores, respectively, the plastic surface is opened for the diffusion of metal ions from the solution of the metal salt. In other words, the plastic surface is sometimes transformed similar to a membrane or an almost diffusion membrane is created on the plastic surface respectively. The conditions of smooth recording, within the scope of the present invention, also means that the recording conditions are applied with the intention that only the mentioned small pores are created on the plastic surface and that the micro-caverns or the inner holes, respectively, on the plastic surface does not occur. In practical terms, diffusion openings or diffusion channels are created in the area of the plastic surface which has a depth of < .09 μm, preferably < .05μm. The treatment for recording comprised in the invention can be carried out with a recording solution and / or basically also by means of a plasma treatment or by a plasma engraving, respectively. Preferably, a recording solution used for recording contains at least one oxidant. Gentle etching within the scope of the invention also means that an oxidant is used in a low concentration. Permanganate and / or peroxydisulfate and / or periodate and / or peroxide can be used as oxidants. According to one type of the process, the engraving is by means of an acid etching solution which contains at least one oxidant. Preferably, an aqueous etchant solution used which contains permanganate or phosphoric acid (H3P0) and / or sulfuric acid. In practical terms, potassium permanganate is used as the permanganate. Very preferably it is the use of a solution to etch acid which only contains phosphoric acid or mainly phosphoric acid and a little sulfuric acid. According to another type of application of the invention, the treatment for engraving is by means of a basic aqueous solution, which contains the permanganate. In the present, potassium permanganate is also preferably used. In practical terms, the basic aqueous solution contains the alkaline solution. This invention refers to the type of used recording solution used depends on the type of plastic to be treated. The preferred concentration of the oxidant in the solution to burn is .05 to .6 mol / l. practical the solution to burn contains .05 to .6 mol / 1 of permanganate or persulfate. The invention also relates to the recording solution containing .1 to .5 mol / l of periodate or hydrogen peroxide. As mentioned above, permanganate is more preferred for the solution to burn. The proportion of the preferred permanganate is lg / 1 up to the solubility limit of permanganate, preferably of potassium permanganate. In terms of practice, a permanganate solution containing from 2 to 15 g / 1 of permanganate, preferably from 2 to 15 g / 1 of potassium permanganate. The invention comprises that the permanganate solution contains a moisturizing agent. - As mentioned before, gentle etching can also be achieved by the use of a dilute aqueous persulfate solution or a solution of periodite or dilute aqueous peroxide solution, preferably, the treatment for soft etching is carried out while the solution is stirred. - Subsequently, to the smooth engraving, the plastic surface is rinsed, for example 1 to 3 minutes with water. In accordance with a very preferred type of application, of the invention, the treatment with the solution of the metal salt according to 1.2) is carried out at a temperature of at most 30 ° C, preferably at a temperature between 15 to 25 ° C. Therefore, it is within the scope of the invention to carry out the treatment with the solution of the metal salt in the range of room temperature. In practice, the treatment with the metal salt solution is carried out without agitation. The preferred treatment time is from 30 seconds to 15 minutes, preferably from 3 to 12 minutes. Preferably, a solution of the metal salt which is used which has a pH value of between 7.5 and 12.5, preferably is adjusted to between 8 and 12. According to a preferred type of the application of the invention, a solution of the metal salt that is used contains ammonia and / or at least one amine. The adjustment of the aforementioned pH value can be carried out with the aid of ammonia and in this case, within the scope of the invention, a solution of the alkali metal salt is used. However, basically, what is also within the scope of the invention, is to use a solution of the metal salt which contains one or more amines. For example, the metal salt solution may contain monoethanolamine and / or triethanolamine. The treatment with the metal salt solution, within the scope of the invention, means in particular the immersion of the plastic surface in the solution of the metal salt. In accordance with a more preferred type of the invention which is especially significant within the scope of the invention refers to that a solution of the cobalt salt is used as the solution of the metal salt. Preferably, the cobalt salt solution contains from 0.1 to 15 g / 1 or of the Co (II) salt, preferably from 5 to 12 g / 1 of the Co (II) salt. In practical terms, the cobalt (II) solution contains cobalt (II) sulfate and / or cobalt (II) chloride. Preferably, the cobalt (II) solution contains .1 to 15 g / 1 of CoS04.7H20; and very preferred is from 1 to 10 g / 1 of CoS0 .7H20.- According to a very preferred embodiment of the application within the scope of the invention a solution of the metal salt used is especially a solution of the cobalt salt , which contains at least one oxidant. The oxidant may be, for example, hydrogen peroxide. The oxidant can also be suitably by blowing air, in the solution of the metal salt. If according to a preferred type of the application of the invention, the solution of the metal salt is a solution of the cobalt (II) salt, the oxidant is preferred to be used with the proviso that at least part of the cobalt (II) is oxidized to Cobalt (III). - Subsequently, upon treatment with the metal salt solution, the plastic surface is washed as required. In accordance with a preferred type of the application of the invention, the plastic surface is immersed in an aqueous alkaline solution between process steps 1.2) and 1.3} . The treatment of the immersion time is preferably 10 seconds to 3 minutes, and from 5 minutes to 2 minutes is more preferred. Preferably, a bath temperature that is used is a. the maximum of 30 ° C, and from 15 to 25 ° C is preferred. For practical purposes, the aqueous alkaline solution has a pH value of 9 to 14. The immersion in the aqueous alkaline solution is preferably in a dilute sodium alkaline solution. The scope of the invention includes the use of sodium hydroxide and / or potassium hydroxide and / or sodium carbonate to make the aqueous alkaline solution. It is much more preferred that the alkaline aqueous solution contains 5 to 50 g / 1 of sodium hydroxide or potassium hydroxide. Preferably in the present invention it is the concentration of the sodium hydroxide or potassium hydroxide to be high, the high concentration of the metal salt of the metal salt solution. In principle, the plastic surface, instead of an aqueous alkaline solution can be treated with an aqueous acid immersion solution.- It is also related within the scope of the invention, to rinse with water or with distilled water respectively, subsequently to the treatment of immersion According to a preferred embodiment of the application of the invention, the plastic surface is treated with an alkaline solution of an alkali metal sulfide in accordance with a step of process 1.3). An ammonium sulfide can also be used. The sulfide, for example, can be a monosulfide, a disulfide, tetrasulfide, or a polysulfide. According to a preferred process an alkali metal sulfide (M2S, M = alkali metal) is used for practical purposes, sodium sulfide (Na2S) is used. The concentration of the alkali metal monosulfide, preferably the sodium sulphide, is preferably from 5 to 10 g / 1, much more preferred is from 2 to 8 g / 1. For practical purposes, the alkaline solution of the alkali metal sulfide it contains from 5 to 25 g / 1 of sodium hydroxide, for example 10 g / 1 of sodium hydroxide. The treatment with the sulfide solution is preferably carried out in a period of time from 15 seconds to 5 minutes, much more preferred is from 30 seconds to 2 minutes. - The treatment with the sulfide solution according to the stage of the process 1.3 ) is preferably carried out at a maximum temperature of 30 ° C: a temperature between 15 and 25 ° C is preferred. - Subsequently the treatment with the sulfide solution is rinsed as required to be carried out, for example 1 to 3 minutes with cold water. Within the scope of the invention such that the solution of the metal salt, preferably a cobalt salt solution and / or the sulfide solution, has added a complex former for the stabilization of the affected solution. Therefore, the solution of the metal salt can at least partially contain the metal in the form of a metal complex. It is further understood within the scope of the invention that the metal salt solution and / or the sulfide solution has a humidifying agent that is added in order to improve the humidifying action of the results of the plastic surface. Within the scope of the invention, a sulfur solution that can be used contains at least one substance from the group of: "alcohol, diol, polyol, polyalkane glycol, polyalkene glycol, gel / sol building substances, such as a silica gel or aluminum oxide gel. "
The use of mixtures of these substances in the sulfide solution is within the scope of the invention. - Within the scope of the invention a solution of the metal salt, preferably a solution of the cobalt salt can be used which contains at least one substance from the group of "Alcohol, diol, polyol, polyalkanol, polyalkene glycol, a substance of gel / sol construction, such as silicic acid gel, or aluminum oxide gel, It is within the scope of the invention to use mixtures of these substances in the metal salt solution. preferred of the application of the invention, the drying of the plastic surface is carried out between the process step 1.3) and the process step 1.4) It is within the scope of the invention that the drying is carried out by heat treatment of the plastic surface (with increased temperature) Preferably, the process to metallize the plastic surface occurs only after drying, in principle, when the conformity procedure is applied. With the invention, the treatment with the metal salt solution and / or the treatment with the sulfide solution can be repeated. Within the scope of the invention such as in the case of multiple treatment with the sulfide solution, the plastic surface is subsequently dried to any treatment.
After completing process step 1.3) the process to metallize directly from the plastic surface can proceed. According to a much more preferred process, which is especially significant within the scope of the invention, the plastic surface is nickel coated in a nickel bath according to process step 1.4). In this degree, a process for electrolytic direct plating can be carried out. The process of depositing nickel electro-chemically is preferably carried out in a Watts electrolyte. In practice, the treatment time is 10 to 15 minutes in this ratio, and the electrolyte temperature is preferably 30 to 40 ° C. It is within the scope of the present invention that for the electrochemical nickel coating, an initial current density of .3 A / dm2 is used which is increased to 3 A / dm2. In this way a layer of nickel can be deposited on the plastic surface by the process for elecrolytic plating. First, the invention is based on the knowledge that the plastic surface when engraving as described in the invention is handled in a manner that ultimately, in a surprising manner, a tightly bonded adhesion of the metal layer applied to the surface of the Plastic is achieved. These bonded bond metal layers show a high temperature cycling resistance and, in accordance with resisting all customary temperature cycling shocks. Furthermore, the invention is based on the knowledge that the use of the process described in the conditions of the invention can be created within a relatively short time, which are optimally suitable for the subsequent application of the metal or the nickel layer respectively. Although it is basic to the scope of the invention that the process steps are repeated and especially steps 1.2) and 1.3) are repeated, surprisingly the optimal results are also achieved without the repetition of these process steps. Within the scope of the invention, with small investment and consumption of small material, high-quality metal layers, especially nickel layers, are obtained on plastic surfaces. It does not require a complex equipment, or traditional or commonly suitable accessories that can be used. In order to apply the process which is the subject of the invention, it is advantageous that only limited space is required. In addition, the time used to apply the process which is the object of this invention is short, so that a substantial time also saves the results when compared with the known processes. Furthermore, the process can be regulated in a simple and functionally safe way, which lately affects the quality of the metal layers. It is of special significance within the scope of the invention that by the application of the measurements contained in the invention, a surprising variety of plastics can be metallized effectively and in a functionally safe manner. This is especially surprising in view of the fact that only a few and certain plastics can be satisfactorily metallized with the aforementioned known process. First, pure ABE can be metallized optimally and smoothly using the process which is the subject of the invention. This also applies to ABE / PC blends and especially also to ABE / PC blends with a relatively high PC component (PC = polycarbonate). The pure PC can also be metallized without problems with the help of the process which is the object of the invention. Such a process to metallize cash, functionally safe, surprisingly, is also possible with most other plastics, among others spatially in the case of the following plastics: POM
(polyoxymethylene), PEEK (polye teretercetona), PP
(Polypropylene) . In view of the fact that, according to the invention, the etching of the plastic surface at elevated temperatures is not necessary, recovering energy that can also be achieved. Due only to the fact that very smooth engraving conditions are required, most of the varied engraving solutions can be used in different ways so that the process which is the subject of the invention is not subject to restrictions from this point of view. In soft etching solutions to conform according to the invention, it is advantageous to remove components of aggressive etching solutions, for example chromic acid. - Due to the fact that preferably the process steps 1.1), 1.2) and 1.3) are carried out at a maximum temperature of 30 ° C, preferably at a temperature of 15 to 25 ° C, the process which is subject to the invention only requires soft conditions in all, in which, among others, it results in a considerable saving of energy. In addition, due to the mild conditions, undesirable side reactions are avoided to an extensive degree. With the process which is the object of the invention, a very selective metallizing process of the plastic surface can be achieved. It is emphasized that with this procedure the use of risks can be avoided in a functionally safe manner. In the following, the process is explained on the basis of an example: Depending on the type of plastic to be metallized, whether a solution is used to record acid or alkaline. In accordance with a preferred type of the application of the invention, a solution for etching acid is used for gentle etching, consisting of 100 to 300 ml / 1 of water, 700 to 900 ml / 1 of concentrated phosphoric acid and 3 to 7 g / 1 potassium permanganate. According to an application example, the acid etch solution consists of 74% by weight of phosphoric acid, 26% by weight of water and 5 g of potassium permanganate. In accordance with another type of application of the invention, a solution for alkaline etching is used for the soft etching, which in practice contains 20 to 40 g / 1 of sodium hydroxide and 5 to 15 g / 1 of potassium permanganate . According to an application example, the aqueous alkaline recording solution consists of 30 g / 1 of sodium hydroxide and 10 g / 1 of potassium permanganate. With the acid etch solution or with the alkaline recording solution explained above, the etching is preferably carried out at room temperature in a period of 10 minutes. Subsequent to the treatment for etching, the plastic surface is rinsed as required. In addition, in accordance with the preferred type of application of the invention, a solution of the ammoniacal metal salt is employed which contains from 0.1 to 12. g / 1 of cobalt sulfate (II), as well as 10 to 50 ml / 1 of a 25% ammonia solution. Activation with the cobalt salt preferably occurs at room temperature, for example during a treatment time of 5 to 10 minutes. Subsequent to activation with the cobalt salt solution, the plastic surface is rinsed with water as required. - For the aqueous alkaline solution in which the part is preferably submerged subsequently to the treatment with the metal salt solution, 10 to 50 g / 1 of sodium hydroxide is dissolved in water. In accordance with an application example, an aqueous alkaline solution with 20 g / 1 of sodium hydroxide is employed. The immersion in the aqueous alkaline solution, in practice is carried out at room temperature and in a period of time of treatment of .5 to 2 minutes. - Preferably, a solution of sulfur, is used as an alkaline sulfide solution. which contains from .5 to 10 g / 1 of sodium sulfide (Na2S), as well as from 5 to 26 g /
1 of sodium hydroxide. According to an example of a preferred application, a solution of alkali alkali sulfide is used, which contains 5 g / 1 of sodium sulfide (Na2S), as well as 10 g / 1 of sodium hydroxide. Preferably, the sulfide treatment is carried out at room temperature and in a treatment period of from 5 to 5 minutes. Subsequently, upon treatment of the sulfide, the plastic surface is rinsed with water as required. Within the scope of the invention prior to the metallizing process, especially the nickel coating, the plastic surface is dried. The invention is explained in greater detail by means of the following six examples. Application examples 1 and 2 correspond to the state of the art (comparison examples), while examples 3 to 6 clarify the process which is the subject of the invention. In application examples 1, 3, and 5, ABE plastic discs with a surface area of 50 cm2 are used, while products embossed with impact resistant polystyrene press with a surface area of 70 cm2 are used for examples 2 , 4 and 6. In the following, the notation "M" corresponds to the concentration "mol / 1".
Application example 1 Plastic ABE discs having a surface area of 50 cm2 are treated with acid for 3 minutes at 70 ° C in a recording solution consisting of 4M H2SO4 and 3.5M Cr03. Subsequently, it is rinsed with water. Next, plastic articles are treated for 30 seconds in an ammonia solution with CuS0. 5H20 .5M which has a pH value of 9.5 and a temperature of 20 ° C. The plastic articles are then submerged for 20 seconds in distilled water and, subsequently, for 30 seconds it is treated with a sulfide solution, which contains Na2S2 .1M and which has a temperature of 20 ° C. After this treatment, the plastic items are washed again with cold water. Following this, it is coated with electrochemical nickel. For this, the articles are treated for 15 minutes with a Watts electrolyte, which contains NiS04.7H20 1.2M, NiCl2.6H20.2M and H3B03.5M. The initial current is .3 A / dm2 and the nickel coating is carried out at 40 ° C. Application Example 2 Impact-resistant polystyrene pressurized articles having a surface area of 70 cm2 are treated with acid for 30 seconds in a recording solution, containing 15 M H2SO4 and .1 M Cr03 and having a temperature of 20 ° C. Subsequently, the articles are washed with water and then submerged for 30 seconds in an emulsion of .2 g / 1 of Xylol and .2g / 1 of Sintanol at 20"C, After the treatment to burn, the articles are washed with water The articles are then treated for 30 seconds with a solution of a metal salt, containing .5 M CuS04.5H20 The monoethanolamine having the pH value is adjusted to 9.8 and the temperature of the solution is 20 C. Subsequently, the articles are immersed in distilled water for 20 seconds and then treated with a solution of sulfur for 30 seconds containing .1M NaS and having a temperature of 20 ° C. Subsequently, the treatment with the solution of the metal salt and the next treatment with the sulfide solution as described above is repeated.After this treatment, the articles are washed with distilled water and electrochemically coated with nickel in a Watts electrolyte as indicated in FIG. scribe in Application Example 1. Application example 3 The surface of the ABE plastic parts are treated with acid at room temperature with a solution of 15M H2S04 and .05M KMn04. After the engraving, the articles are rinsed with water and subsequently treated in an ammoniacal solution for 10 minutes which contains .1M of C0SO4 and has a pH value of 10 as well as the temperature is of 20 ° C. Following this, the articles are treated with water which have been acidified with H2SO4 at a pH value of 1. Subsequently, for a period of 30 seconds, there is a treatment with a sulfide solution containing .01 M Na2S2. After this treatment, the articles are rinsed with distilled water, and then electrochemically coated with nickel with a Watts electrolyte in accordance with Application Example 1. Application Example 4. The surface of polystyrene articles resistant to impact are treated with acid, for a period of 10 minutes at room temperature with a solution containing 17M of H2SO4 and 1M of H2O2. After etching, the articles are rinsed with water and subsequently treated for 10 minutes with a solution containing .01M CoF3 and monoe anolamine up to a pH value of 8 and at a temperature of 20 ° C. The articles are then immersed for 20 seconds in an aqueous alkaline solution which contains sufficient sodium hydroxide having a pH value of 14. Subsequently, they are treated for 30 seconds with a sulfide solution containing .05 of K2S4. The treated articles are then rinsed, with distilled water, dried and then nickel-coated for 15 minutes in a Watts electrolyte according to the Example of
Application 1.
Application Example 5 The surfaces of ABE plastic articles are treated with acid at room temperature with a solution which contains 13M of H3P04 and .5 of K2S209. After the engraving, the articles are rinsed with water. Subsequently, they are treated for 10 minutes with a solution containing .25M of C0SO4 and triethanolamine up to a pH value of 9 to 20 ° C. After which, the articles are immersed in an aqueous alkaline solution which has been adjusted to a value of 9 with sodium carbonate. Subsequently, they are treated for 30 seconds in a sulfide solution, which contains .02 of K2S3. After the treatment, the plastic articles are rinsed with distilled water, dried and subsequently, in a period of time of 15 minutes, the electrochemical coating with nickel, uses a Watts electrolyte in accordance with Application Example 1.
Application Example 6. The surface of the impact-resistant polystyrene articles are treated with acid at room temperature with a solution containing 17M H2SO4 and 0.5M KI04. After recording, the articles are rinsed with water and subsequently treated with a solution containing .01M CoF, which has been adjusted to a pH value of 12 with ammonia and which has a temperature of
20 ° C. The articles are submerged for 20 seconds in an acid solution which has been adjusted to a pH value of 5 with the aid of acetic acid. Subsequently, the articles are treated for 30 seconds in a sulfide solution which contains 0.1 Na2S. After this treatment, the articles are rinsed with distilled water, dried and subsequently coated with electrochemical nickel for 15 minutes, using a Watts electrolyte in accordance with Application Example 1. The data related to the process is carried out from according to Application Examples 1 to 6, as well as the properties of the resulting metal layers are mentioned in the following table.