JPS6160156B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an economically advantageous method for electroplating plastic moldings. More specifically, it relates to a plating method that does not require replacing the plating jig (i.e., the jig to which the plastic molded product to be plated is attached and energized) during the plating process. That is, the present invention is a plastic plating method characterized by immersing a plating jig in a solution of a sulfur-containing organic compound, attaching a plastic molded article, and applying plating. A plating jig is generally made of copper or a copper alloy, which is a good electrical conductor, and is adapted to attach one or more objects to be plated. In addition, to prevent the jig itself from being plated when plating is performed, the surface of the jig is masked by coating the surface of the jig with an insulator such as vinyl chloride, except for necessary parts. However, in plating plastic molded products, there is a step of making the molded product electrically conductive during the plating process. For this reason, there is a problem in that the coating surface of the plating jig also becomes conductive, and electroplating cannot be performed. For this reason, when plating plastics, the plating jig is replaced up to the process of making the molded product conductive (so-called chemical plating) and in the subsequent electroplating process, that is, the jig is replaced. The labor costs for this are extremely large and account for a large portion of the plastic plating cost. In addition, taking the semi-finished product out into the atmosphere during the plating process and touching it with human hands causes problems such as oil and fat adhesion and scratches on the surface of the molded product, which causes plating defects. The present invention prevents plating from adhering to the coating surface of the jig by immersing a regular plating jig in a specific chemical solution before use. This is a method of plating plastic that can do the following. The plating method of the present invention is characterized by immersing the plating jig in a solution of sulfur-containing organic compounds such as mercapto compounds, thiocarbonyl compounds, and sulfide compounds before plating. It is similar to Experiments have shown that most sulfur-containing organic compounds are effective. That is, mono- or disulfide compounds, sulfur-containing cyclic compounds such as thiazole, thiolane, thian, thio group (-S-), sulfonyl group

[Formula] Thiocarbonyl group

[Formula] A sulfur compound containing a mercapto group (-SH). To give a concrete example,
Tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetra-n-butylthiuram disulfide, dimethyldiethylthiuram disulfide, diphenyl disulfide, thiazole, benzothiazole, thiolane, thiane,
Thianthrene, 2-thiobarbituric acid, dithioamelide, thiophene, aminothiophene, acetylthiophene, thiourethane, ethyl disulfide, phenyl disulfide, β,β′-dithiodipropionic acid, thioacetaldehyde, dimethyl sulfoxide, ethyl sulfoxide, -n-butyl sulfoxide, dithiohydantoin, thiourea, 1,3
-diphenyl-2-thiourea, 2,2'-ditolylthiourea, 2-mercaptobenzothiazole, thiosalicylic acid, 2,5-dimercapto-1,3,
Examples include, but are not limited to, 4-thiadiazole, thiophenol, thiocresol, ethanedithiol, propylmercaptan, and thioindigo. The solvent may be any solvent as long as it dissolves the sulfur-containing organic compound, but water-soluble solvents are preferred from the viewpoint of contamination of the plating solution. For example, alcohols such as ethanol, butanol, and diacetone alcohol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and ethers such as ethyl ether are suitable solvents because they are readily available and easy to handle. However, hydrophobic solvents such as toluene, xylene, trichloroethane, etc. can also be used if they are dried after dipping. It is effective if the concentration of the solution is 1% or more, but
Since it is generally used repeatedly, a concentration of 3 to 20% is suitable. A plating jig is immersed in such a solution before the plating process. No special technique is required for the dipping method. All you have to do is put the plating jig into the solution.
Normally, it is sufficient to attach a treatment tank to the automatic line. The immersion temperature and time vary slightly depending on the type of sulfur-containing organic compound and the concentration of the solution, but the temperature ranges from room temperature to the boiling point of the solution, and the time varies depending on the temperature conditions, but if it is 1 minute or more, You can work for as many hours as you like, depending on your work schedule. In terms of metal adhesion prevention effect, it can be said that the higher the temperature and the longer the time, the greater the effect. A plating jig immersed in a solution of a water-soluble solvent is usually washed once or twice with the solvent and/or water before use. When a hydrophobic solvent is used, it is advisable to wash it several times with the solvent and dry it before use. In principle, the effect of preventing metal adhesion is only available once, and the immersion treatment is performed every time the jig is used. In some cases where the sulfur-containing organic compound was a sulfide compound or a mercapto compound, metal precipitation was not observed even after the jig was used twice or more. In such cases, the number of immersions can be reduced to several times at once. The present invention will be specifically explained below using examples. Example 1-16 An ordinary plating jig coated with vinyl chloride sol was immersed (50% ℃, 30 minutes), washed with diacetone alcohol and then water, and air-dried. When an acetal resin molded product was hung on this jig, degreased, etched with an etching liquid consisting of sulfuric acid/phosphoric acid, catalyzed and activated, and chemically nickel plated, no chemical plating was deposited on the jig. , only the molded parts were nickel plated. Subsequently, this material was electroplated with copper, nickel, and chromium in that order, and as shown in Table 1, no metal adhered to the jig. As a comparison, when a plating jig coated with vinyl chloride sol was subjected to plating as it was without being treated with a sulfur-containing organic compound, plating was deposited on the entire surface of the jig from the first time, as shown in Comparative Example 1 in Table 1. . Therefore, the jig had to be replaced after chemical plating.

[Table] Example 17-21 A plating jig coated with chloride beer sol was immersed in each concentration shown in Table 2 of the sulfur-containing organic compound solution (solvent diacetone alcohol) (50°C, 30 minutes). ) and plated in the same manner as in Example 1, and the degree of metal adhesion to the jig was observed, and the results shown in Table 2 were obtained. As is clear from the table, the effect was observed even at 1%.

[Table] Example 22-25 A plating jig coated with vinyl chloride sol was dissolved at 10% by weight in the solvent shown in Table 3 using tetra-n-butylthiuram disulfide as the sulfur-containing organic compound. Table 3 shows the results of observing the degree of metal adhesion to the jig. As is clear from the table, the same effect is observed not only with water-soluble solvents but also with hydrophobic solvents, and it can be seen that the immersion conditions are not subject to any restrictions.

【table】

[Table] Regarding Example 2, chemical copper plating solution was used instead of chemical nickel plating solution, and ABS
We also tested a commonly used high chromic acid/sulfuric acid etching solution for plating, and found similar effects, confirming that it can be used in a wide range of applications. By implementing the present invention, metal is no longer deposited on the plating jig during the plastic plating process, so it is no longer necessary to replace the jig during plating, and it has become clear that the cost of plastic plating can be significantly reduced. Ta. Another great effect is that the scratches and poor plating adhesion that occur when replacing hooks are eliminated, and the defective rate can be greatly reduced.

Claims (1)

[Scope of Claims] 1. A method for plating plastic, which comprises immersing a plating jig in a solution of a sulfur-containing organic compound, then attaching a plastic molded article and applying plating. 2. The plating method according to claim 1, wherein the sulfur-containing organic compound is a sulfide compound. 3. The plating method according to claim 1, wherein the sulfur-containing organic compound is a mercapto compound. 4. The plating method according to claim 1, wherein the solvent of the sulfur-containing organic compound solution is water-soluble.