JP4526621B2 - Method of metal plating on electrical non-conductor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for plating a metal on an electrically non-conductive material, and more specifically, an electrical method in which plating has conventionally been difficult or impossible, such as silicone rubber, polyethylene rubber or EPR (ethylene-propylene-rubber). The present invention relates to a method in which metal plating can be easily applied to a nonconductor.
[0002]
[Prior art]
It is generally difficult to apply metal plating to the surface of an electrical non-conductor represented by plastic or the like. This is because the surface of the non-conductive substrate is smooth and it is difficult to form a catalytic metal layer as a pretreatment. Therefore, conventionally, after a mechanical treatment such as blasting or liquid honing is applied to the surface of the non-conductive substrate to roughen the surface, or the surface is chemically roughened with a strong agent such as chromic acid, A method of forming a metal plating layer on the surface of a base material by using the above has been adopted.
[0003]
However, in the method in which the surface of the base material is mechanically roughened and the metal plating is performed as described above, it is difficult to perform the treatment on an intricate portion of an article having a complicated external shape, and it cannot be uniformly roughened. For this reason, the appearance after plating is poor, and various drawbacks such as easy peeling due to poor adhesion are pointed out. In addition, in the method (etching) in which the surface of the base material is chemically roughened and then metal plating is performed, an appropriate treatment according to the type of the base material is indispensable, and there is a problem that it is inferior in versatility.
[0004]
As a treatment suitable for the substrate, for example, it is known to roughen the surface of an ABS material with a sulfuric acid-chromic anhydride solution. According to this, a high quality appearance and good adhesion can be obtained, and this is widely used as a standard prescription for plastic plating. Since the present invention relates to a metal plating method for a non-conductive material, an outline of a conventional metal plating method for an ABS-based material will be described first for the sake of understanding.
[0005]
First, the surface of an ABS material, which is an object to be plated, is etched with, for example, dichromic acid to be roughened by oxidation, and then immersed in a conditioner that improves the adhesion of a catalyst substance (described later). Next, it is washed with water, for example, immersed in a palladium / tin catalyst bath to give an indispensable catalyst for deposition of electroless plating. Apply.
[0006]
Next, a conductive step for forming a conductive layer is performed. In this conductive step, the ABS material is immersed in an electroless plating bath of nickel for a predetermined time to perform electroless plating, and an electroless plating serving as a conductive layer is deposited on the surface. This conductive step is indispensable for the subsequent electroplating step. The ABS-based material that has undergone the conductive step is subjected to electroplating as necessary to form, for example, a nickel metal plating layer. This electroplating step is completed by immersing the ABS material in a nickel sulfamate bath for a predetermined time, energizing the conductive layer to deposit a nickel metal film to a desired thickness.
[0007]
Materials other than the ABS-based materials described above, such as polyphenylene oxide resin, polypropylene resin, polycarbonate resin, polycarbonate alloy, polyacetal resin, nylon resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene sulfide resin, polyetherimide resin For example, it is possible to form a practical plating by an established pretreatment method including a chemical roughening step corresponding to each material.
[0008]
[Problems to be solved by the invention]
However, as described above, even though pretreatment methods corresponding to various resins have been established, conductive filler is included in the material, alloyed, or pre-etching with an organic solvent is performed as pretreatment. Since there are many restrictions such as necessary, the formation of plating on non-conductors has a difficulty in that there are few degrees of freedom. In general, it is impossible to plate rubbers with the prior art.
[0009]
In recent years, interest in various water pollutants has been increasing, and a wide range of regulations regarding the disposal of water pollutants are being made. Therefore, it is pointed out that the waste liquid such as hexavalent chromium generated by the chemical roughening treatment with the sulfuric acid-chromic anhydride solution described above also increases the cost required for the post-treatment for clearing the regulation.
[0010]
OBJECT OF THE INVENTION
In view of the problems inherent in the metal plating method for electrical non-conductors according to the prior art, the present invention has been proposed to suitably solve this problem. It is an object of the present invention to provide a method for easily applying metal plating to electrical non-conductors, such as silicone rubber and other materials, which has been difficult or impossible in the past.
[0011]
[Means for Solving the Problems]
In order to overcome the above-mentioned problems and achieve the intended purpose, the metal plating method for the electrical non-conductor of the present invention includes:
Moisture curable resin , in which the functional groups in the structure react and solidify by absorbing moisture, is applied to the surface of the base material that is electrically non-conductive by a roll coater or spray ,
After forming the primer layer by drying and curing the moisture curable resin provided with the functional group in an unreacted state on the surface of the base material,
Forming a catalytic metal layer by contacting a catalytic metal having catalytic activity with respect to the electroless plating metal to the primer layer;
The catalyst metal layer is subjected to electroless plating to form a required metal plating layer.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the metal plating method for an electrically non-conductive material according to the present invention will be described below with reference to the accompanying drawings. The inventor of the present application provides a moisture curable resin primer as a pretreatment step to a silicone rubber base material, for example, where metal plating could not be formed so far. It has been found that a metal plating layer having high adhesion can be easily formed without performing surface roughening treatment using means.
[0013]
As shown in FIG. 1, the method for plating a metal on an electrically non-conductive material according to the present invention is largely divided into a pretreatment step S1 and a conductive step S2. As shown in FIG. 2, the pretreatment step S1 includes a primer application step S11 for applying a moisture curable resin 20 to be described later to the electrically non-conductive base material (rubber member) 10 by means such as spray coating, and this moisture. It comprises a drying step S12 in which the primer layer 12 formed of the curable resin 20 is dried by a predetermined means.
[0014]
As shown in FIGS. 1 and 3, the conductive step S <b> 2 performed after the pretreatment step S <b> 1 is performed on the primer layer 12 on the substrate 10 with desired metal fine particles exhibiting catalytic activity against electroless plating. A catalyst adsorption step S21 for adsorbing the catalyst metal 22 containing the catalyst metal 14 to form a catalyst metal layer 14 and a plating bath 30 of an appropriately selected plating metal 24 so as to have a predetermined thickness on the catalyst metal layer 14 The electroless plating step S22 for applying the metal plating layer 16 is included. After passing through the above steps, the inspection in the inspection step S3 is performed to complete the application of the metal plating to the electrical non-conductor. In some cases, subsequent to the electroless plating step S22, an electrolytic plating step S23 is performed to form a thicker metal plating layer 16. This electrolytic plating step S23 is selectively performed as appropriate according to various physical properties (for example, conductivity) required for electrical non-conductors.
[0015]
The base material to be plated in the present invention can be selected without any problem as long as it is a substance that has been extremely difficult to be metal plated so far and can impart the moisture curable resin to the surface. Preferable examples include silicone rubber, natural rubber, butadiene rubber, styrene butadiene rubber, nitrile rubber, ethylene / propylene rubber, polyethylene, polypropylene, polyacetal, etc. In addition, general polymer materials and highly polar inorganic materials, etc. Can also be granted.
[0016]
The moisture curable resin used in the present invention is mainly known in the field of adhesives, and is a resin having the property of causing cross-linking in the structure by absorbing moisture in the air and solidifying by this cross-linking. The blended resin blend is generally referred to. The moisture curable resin is applied on the base material in a thickness range of about 1 to 100 μm according to the type of the base material. Suitable examples of the moisture curable resin include a moisture curable silicone resin, a cyanoacrylate resin, and a urethane moisture adhesive. In the moisture curable silicone resin, a hydrolyzable functional group in the structure and a silanol group generated by moisture cause a condensation reaction to cause cross-linking. It is classified into acetic acid type, alcohol type, oxime type, amine type, amide type, aminoxy type, acetone type, etc., depending on the condensation reaction by-products. The cyanoacrylate resin is widely known as an instantaneous adhesive, and is cured by the polymerization reaction in the composition accelerated by moisture. The urethane moisture adhesive contains an oligomer at the end of the isocyanate group in the structure, and the amino group resulting from the reaction between the isocyanate group and moisture further crosslinks by reacting with another isocyanate group. It is produced and cured.
[0017]
Since these moisture curable resins generally have a high viscosity, they can be applied by coating with a roll coater or the like. Since the concentration can be adjusted with a solvent such as xylene, a uniform and thin primer layer can be easily formed. Moreover, since it hardens | cures by atmospheric humidity, a cure rate can also be easily controlled by controlling the humidity at the time of the provision to a base material. Moisture curable resins have a high physical adhesion ability to various substances and have many functional groups newly generated by reaction with functional groups remaining in the structure in an unreacted state after curing or with moisture. Capturing a catalytic metal colloid or a surfactant functional group that stabilizes the colloid, which will be described later, and adsorbing a large number of the catalytic metal as a result, indirectly provides strong adhesion of the plating layer It is inferred that
[0018]
As the catalytic metal used in the present invention, those having catalytic activity for the electroless plating reaction described later are suitable, and examples thereof include gold, silver, ruthenium, rhodium, palladium, iridium, osmium, and platinum. Is used under colloidal conditions. In order to produce the catalyst metal colloid, a general method is to dissolve a water-soluble salt containing the catalyst metal, add a surfactant, and add a reducing agent while stirring vigorously. May be used. As the surfactant, anionic or cationic, for example, soap, sodium higher alcohol sulfate, sodium alkylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, lauryltrimethylammonium chloride or alkylbenzyldimethylammonium chloride, It is appropriately selected depending on the catalyst metal. The catalyst metal layer formed here acts as a nucleus when forming a metal plating layer by electroless plating, which will be described later, so it is not necessary to form a continuous layer with respect to the primer layer, and is dispersed and adsorbed. Just do it.
[0019]
Further, the electroless plating metal used in the present invention includes electroless copper, electroless copper / nickel / phosphorous alloy, electroless nickel / phosphorous alloy, electroless nickel / boron alloy, electroless cobalt / phosphorous alloy. Electroless gold, electroless silver, electroless palladium, and the like. Depending on the degree of conductivity of the metal plating layer applied to the substrate, the metal plating layer is formed through an electrolytic plating step as necessary. In this case, the plating metal is preferably electroless copper or electroless nickel / phosphorous alloy from the viewpoint of cost and stability in consideration of the transition to the electrolytic plating stage.
[0020]
Although the suitable Example of the metal plating method to the electrical nonconductor which concerns on this invention below is shown, it is not limited to this.
[0021]
[First embodiment]
As a base material used in this example, a silicone rubber sheet (product name: manufactured by Toshiba GE Silicone) having a size of 100 × 100 × 3 mm was used. The following operation was performed to form a metal plating layer on one side of the silicone rubber sheet.
As a pretreatment process
(1) Primer application step: A 50% xylene solution of moisture curable silicone resin (trade name Super X: manufactured by Cemedine Co.) is spray-applied to the silicone rubber sheet so that the dry thickness of the primer layer is 10 μm. did.
(2) Drying step: Using a high-temperature oven capable of setting the temperature, drying was performed at a temperature of 60 ° C. for 30 minutes.
As a conductive process,
( ₃ ) Catalyst adsorption step: Stearyltrimethylammonium chloride (product name: Cotamine 86P Conch) was added to a pure aqueous solution consisting of 0.089 g / L of palladium chloride (PdCl ₂ ) and 0.146 g / L of sodium chloride (NaCl). A dark brown transparent palladium colloid catalyst solution by vigorously stirring while adding a solution prepared by dissolving 0.076 g of sodium borohydride (NaBH ₄ ) in a small amount of pure water to the main solution added with 1 g / L. Was made. This palladium colloid catalyst solution was sufficiently applied by spray coating on the silicone rubber sheet prepared in the pretreatment step, and then dried for 30 minutes at a temperature of 100 ° C. in a high-temperature oven capable of setting the temperature.
(4) Electroless plating step: An electroless nickel plating bath (product name: TMP chemical nickel: manufactured by Okuno Pharmaceutical Co., Ltd .: standard composition) was carried out at a temperature of 30 ° C. for 10 minutes.
(5) Electrolytic plating step: Next, a bright nickel bath (product name # 66: manufactured by EBARA Eugeneite Co., Ltd .: standard composition) is carried out for 30 minutes at a temperature of 30 ° C. and a current intensity of 2 A / dm ² to obtain a thickness of 12 μm. A metal plating layer of nickel metal was formed.
[0022]
In order to evaluate the adhesion of the metal plating layer obtained through each of the above steps, a test piece was prepared by fixing the sheet-like material provided with the metal plating layer to the iron plate with a moisture curing adhesive Super X Then, the adhesion force was measured according to “Electroplating for decoration on plastic, Annex 6 Adhesion test method” prescribed in JIS H 8630. Specifically, two parallel cuts with a width of 10 mm are made in the metal plating layer, and the peeling part of about 20 mm formed by pliers or the like is fixed to the head of a tensile tester by causing the cut to occur. The load cell value was measured by pulling the head and the base material (iron plate) at an angle of 90 ° and a head moving speed of 25 mm / min. The load cell value at this time was about 14.7 N / cm, and sufficient adhesion was confirmed.
[0023]
[Second embodiment]
As a base material used in this example, a flexible polyvinyl chloride sheet having dimensions of 100 × 100 × 0.125 mm was used. The following operation was performed to form a metal plating layer on both sides of the vinyl sheet.
As a pretreatment process
(1) Primer application stage: Moisture curable silicone resin (trade name Super X: manufactured by Cemedine) is applied to a soft polyvinyl chloride sheet so that the dry thickness of the primer layer is 5 μm. The coating was applied by a roll coater under supply.
(2) Drying step: Drying was performed simultaneously with resin application by supplying dry air.
As a conductive process,
( ₃ ) Catalyst adsorption step: Stearyltrimethylammonium chloride (product name: Cotamine 86P Conch) was added to a pure aqueous solution consisting of 0.089 g / L of palladium chloride (PdCl ₂ ) and 0.146 g / L of sodium chloride (NaCl). A dark brown transparent palladium colloid catalyst solution by vigorously stirring while adding a solution prepared by dissolving 0.076 g of sodium borohydride (NaBH ₄ ) in a small amount of pure water to the main solution added with 1 g / L. Was made. The palladium colloid catalyst solution was sufficiently applied by spray coating on the soft polyvinyl chloride sheet prepared in the pretreatment step, and then dried for 30 minutes at a temperature of 100 ° C. in a high temperature oven.
(4) Electroless plating step: An electroless copper plating bath (product name Omnishield 1598: manufactured by Shipley Far East Co., Ltd .: standard composition) was carried out at a temperature of 30 ° C. for 10 minutes.
(5) Electrolytic plating step: Next, a bright copper sulfate bath (product name: UBAC-EPII: manufactured by Ebara Eugelite Co., Ltd .: standard composition) is carried out for 15 minutes at a temperature of 25 ° C. and a current intensity of 4 A / dm ² . A 12 μm thick copper metal plating layer was formed.
[0024]
In order to evaluate the adhesion of the metal plating layer obtained through each of the above steps, a sheet-like material provided with the metal plating layer was fixed to an iron plate with a moisture-curing adhesive Super X, and a test piece was prepared. The adhesion was measured according to “Electroplating for decoration on plastic, Annex 6 Adhesion test method” defined in JIS H 8630. Specifically, two parallel cuts with a width of 10 mm are made in the metal plating layer, and the peeling part of about 20 mm formed by pliers or the like is fixed to the head of a tensile tester by causing the cut to occur. The load cell value was measured by pulling the head and the base material (iron plate) at an angle of 90 ° and a head moving speed of 25 mm / min. The load cell value at this time was about 9.8 N / cm, and sufficient adhesion was confirmed.
[0025]
[Third embodiment]
As a base material used in this example, an EPDM rubber sheet (manufactured by Inoac Elastomer Co., Ltd.) having a size of 100 × 100 × 3 mm was used. The following operation was performed to form a metal plating layer on both sides of the EPDM rubber sheet.
As a pretreatment process
(1) Primer application stage: Spray coating of a 50% xylene solution of moisture-curing silicone resin (trade name Super X: manufactured by Cemedine Co.) onto the EPDM rubber sheet so that the dry thickness of the primer layer is 10 μm. did.
(2) Drying step: Using a high-temperature oven capable of setting the temperature, drying was performed at a temperature of 60 ° C. for 30 minutes.
As a conductive process,
(3) Catalyst adsorption stage: 0.1 g / L of stearyltrimethylammonium chloride (product name: Cotamine 86P Conch) into a pure aqueous solution of sodium tetrachloroaurate (III) (NaAuCl ₄ .2H ₂ O) of 0.199 g / L A red transparent gold colloid catalyst solution was prepared by vigorously stirring the added main solution while adding a solution prepared by dissolving 0.076 g of sodium borohydride (NaBH ₄ ) in a small amount of pure water in advance. . The gold colloid catalyst solution was sufficiently applied by spray coating on the EPDM rubber sheet prepared in the pretreatment step, and then washed with water. Then, it was dried at a temperature of 100 ° C. for 30 minutes in a high-temperature oven capable of setting the temperature.
(4) An electroless copper plating bath (product name Omnishield 1598: manufactured by Shipley Far East Co., Ltd .: standard composition) was carried out at a temperature of 30 ° C. for 30 minutes. Next, an activation bath containing palladium chloride (Omnishield 1501: manufactured by Shipley Far East Co., Ltd .: standard formulation) was run for 1 minute at a temperature of 25 ° C. and thoroughly washed with water, and finally an electroless nickel plating bath (product name) Omnishield 1580 (manufactured by Shipley Far East Co., Ltd .: standard composition) was carried out at a temperature of 30 ° C. for 15 minutes.
By the above two-stage electroless plating, an EPDM rubber sheet in which a copper plating layer and a nickel plating layer were formed and laminated by 1 μm each was produced.
[0026]
In order to evaluate the adhesion of the metal plating layer obtained through each of the above steps, a sheet-like material provided with the metal plating layer was fixed to an iron plate with a moisture-curing adhesive Super X, and a test piece was prepared. Adhesion was evaluated according to “Tape Test Method” in “Plating Adhesion Test” defined in JIS H 8504. Specifically, a square stripe having a side of 2 mm that completely penetrates the metal plating layer was formed with a cutter, and a cellophane tape having a width of 12 mm was pressed for 10 seconds to make contact. Next, the cellophane was peeled off instantaneously under the condition of being perpendicular to the metal plating layer surface, and the peeled state was confirmed. The peeling was not recognized about the metal plating layer concerning a present Example. Moreover, after performing the immersion process for 4 hours in 60 degreeC warm water, the same peeling test was done, but peeling did not arise but it was confirmed that the strong metal plating layer is formed.
[0027]
[Fourth embodiment]
As a base material used in this example, a natural rubber sheet having a size of 100 × 100 × 1 mm was used. The following operation was carried out to form a metal plating layer on one side of the natural rubber sheet.
As a pretreatment process
(1) Primer application step: A cyanoacrylate resin (instant adhesive: trade name: Cemedine 3000D: manufactured by Cemedine) was applied to a natural rubber sheet by brush coating so that the dry thickness of the primer layer was 10 μm.
(2) Drying step: Using a high-temperature oven capable of setting the temperature, drying was performed at a temperature of 60 ° C. for 30 minutes.
As a conductive process,
( ₃ ) Catalyst adsorption step: Stearyltrimethylammonium chloride (product name: Cotamine 86P Conch) was added to a pure aqueous solution consisting of 0.089 g / L of palladium chloride (PdCl ₂ ) and 0.146 g / L of sodium chloride (NaCl). A dark brown transparent palladium colloid catalyst solution by vigorously stirring while adding a solution prepared by dissolving 0.076 g of sodium borohydride (NaBH ₄ ) in a small amount of pure water to the main solution added with 1 g / L. Was made. This palladium colloid catalyst solution was sufficiently applied by spray coating on the silicone rubber sheet prepared in the pretreatment step, and then dried at a temperature of 100 ° C. for 30 minutes in a high-temperature oven capable of setting the temperature.
(4) Electroless plating step: An electroless nickel plating bath (product name: TMP chemical nickel: manufactured by Okuno Pharmaceutical Co., Ltd .: standard composition) was plated at a temperature of 30 ° C. for 10 minutes.
(5) Electrolytic plating step: Next, a bright nickel bath (product name # 66: EBARA Eugleite Co., Ltd .: standard composition) was carried out for 30 minutes under the conditions of a temperature of 30 ° C. and a current intensity of 2 A / dm ² . A metal plating layer of nickel metal was formed.
[0028]
In order to evaluate the adhesion of the metal plating layer obtained through each of the above steps, a sheet-like material provided with the metal plating layer was fixed to an iron plate with a moisture-curing adhesive Super X, and a test piece was prepared. Adhesion was evaluated according to “Tape Test Method” in “Plating Adhesion Test” defined in JIS H 8504. Specifically, a square stripe having a side of 2 mm that completely penetrates the metal plating layer was formed with a cutter, and a cellophane tape having a width of 12 mm was pressed for 10 seconds to make contact. Next, the cellophane was peeled off instantaneously under the condition of being perpendicular to the metal plating layer surface, and the peeled state was confirmed. The peeling was not recognized about the metal plating layer concerning a present Example. Moreover, after performing the immersion process for 4 hours in 60 degreeC warm water, the same peeling test was done, but peeling did not arise but it was confirmed that the strong metal plating layer is formed.
[0029]
【The invention's effect】
As described above, according to the metal plating method on the electrical non-conductor according to the present invention, it is higher than the electrical non-conductor such as rubber which has been difficult or impossible to form a metal plating layer until now. It became possible to easily apply metal plating having uniformity and adhesion. For example, with the addition of conductivity to the rubber member by metal plating, a conductive roller or the like having a high nip and conductivity essential for laser printers and copying can be suitably produced. In addition, the present invention has a beneficial effect that metal plating can be similarly applied to a wide variety of substances including substances that are difficult to form other metal plating layers. Furthermore, the use of substances such as chromium, which are highly toxic and environmentally burdensome, can be avoided, so that there are no post-treatment problems associated with disposal of pollutants.
[Brief description of the drawings]
FIG. 1 is a flowchart showing steps of a metal plating method according to an embodiment of the present invention.
FIG. 2 is a process diagram showing each stage of a pretreatment process in a metal plating method according to an embodiment of the present invention.
FIG. 3 is a process diagram showing each stage of a pretreatment process in a metal plating method according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Base material 12 Primer layer 14 Catalyst metal layer 16 Metal plating layer 20 Moisture curable resin 22 Catalyst metal

Claims (6)

Moisture curable resin (20), which is solidified by the reaction of functional groups in the structure by absorbing moisture, is applied to the surface of the electrically non-conductive substrate (10) by a roll coater or spray ,
After forming the primer layer (12) by drying and curing the moisture curable resin (20) provided with the functional group in an unreacted state on the surface of the substrate (10),
Forming a catalytic metal layer (14) by contacting a catalytic metal (22) having catalytic activity with respect to the electroless plating metal to the primer layer (12),
A method of plating a metal on an electrically non-conductive material, wherein the catalyst metal layer (14) is electrolessly plated to form a required metal plating layer (16).   The method for metal plating on an electrically non-conductive material according to claim 1, wherein a silicone resin is used as the moisture curable resin (20).   The metal plating method for an electrically non-conductive material according to claim 1, wherein a cyanoacrylate resin is used as the moisture curable resin (20).   The method for metal plating on an electrically nonconductive material according to any one of claims 1 to 3, wherein rubber is used as the base material (10).   The method for metal plating on an electrically non-conductive material according to any one of claims 1 to 4, wherein the catalytic metal (22) is applied in a colloidal state.   6. The method for plating a metal on an electrically non-conductive body according to any one of claims 1 to 5, wherein electrolytic plating is performed subsequent to the electroless plating.

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