JP3722724B2 - Manufacturing method of plated molded products - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a two-color molded product plated in silver or black, and more specifically, for example, electrical and electronic parts such as switches and key tops for PC operation, OA equipment such as personal computers and telephones, The present invention relates to a method for plating a surface of a communication device such as a DVD or MD, and more particularly to a method for manufacturing an operation button (key) of a mobile phone.
[0002]
[Prior art]
Conventionally, when plating a molded product such as a cellular phone button, the molded product is pretreated (chemical treatment), washed with water, then nickel plated, washed with water, chrome plated, washed with water, It is dry. Here, the chromium plating solution used uses a bath composition containing hexavalent chrome, ionizes the hexavalent chromium, and forms a metallic chromium film on the surface of the target product by electrophoresis. Metallic chromium coating is hexavalent, although ions do not exist, such as trivalent, human are concerned about adverse effects on the skin, also naturally by oxidation to hexavalent chromium by metallic chromium corrosion after the processed product is discarded It remains a problem to remain.
[0003]
Therefore, conventionally, a treatment method using only trivalent chromium in the chromium plating solution has been studied, but trivalent chromium is used from the beginning as compared with the conventional method of forming a metal film with only hexavalent chromium. It has been found that the method does not provide sufficient film formation and has poor corrosion resistance.
[0004]
In addition, when plating a two-color molded product mobile phone operation button with a newly introduced trivalent chromium plating bath, if the plating processing conditions are within the standard control values from the manufacturer, There are some problems that are not enough to manage the specs, and standard control values and equipment changes are required.
[0005]
For example, fine irregularities may be formed on the surface of the plated product. This is probably because dust mixed in the liquid and impurities generated during electrolysis are taken into the plating film. In addition, there is a case where the plating coverage (uniform electrodeposition property) may be poor, and this is presumed to be because the current cannot flow at the standard current density because of the product shape with large irregularities.
[0006]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above-mentioned actual condition, and the object is to form a plating film capable of forming a chemical conversion film having excellent corrosion resistance by a surface treatment using a treatment liquid not containing hexavalent chromium. It is in providing the manufacturing method of goods.
[0007]
[Means for Solving the Problems]
The method for producing a plated molded product of the present invention is obtained by two-color molding comprising a primary molded product formed of ABS resin and a secondary molded product formed of polycarbonate resin inside the primary molded product. A method of manufacturing a plated molded product by treating trivalent chromium plating on the surface of the molded product, wherein the molded product is an operation button for a mobile phone, and the primary molded product has a thickness of 0.15 to 0.15. Having a thin wall of 0.30 mm, whereby the above objective is achieved:
(A) Trivalent chromium liquid concentration in the plating bath: 6 to 10 g / liter,
(B) Total impurity amount in the plating bath: 60 ppm or less,
(C) Bath temperature: 40-50 ° C.
(D) pH of the plating bath: 3.2 to 3.6
(E) Cathode current density: 3-5 A / dm ²
(F) Anode / cathode ratio: 1.5-2: 1.
In the present invention, the anode / cathode ratio means the ratio of the surface area of the anode and the cathode.
[0008]
In one embodiment, the plating conditions further include:
(G) Rectifier: Use a rectifier that has a capacity of three times or more of the total current.
(H) Filtration capacity: The bath liquid is passed through the filtration section provided in the plating bath at least 7 rotations per hour with respect to the bath amount.
[0009]
In one embodiment, the molded product is a silver color operation button of a mobile phone.
[0010]
Another method for producing a plated molded product of the present invention is a two-color molding comprising a primary molded product formed of ABS resin and a secondary molded product formed of polycarbonate resin inside the primary molded product. A method for producing a plated molded product, in which trivalent chromium plating is processed on the surface of the molded product obtained by the above method, wherein the molded product is a button for operating a mobile phone, and the primary molded product has a thickness of 0. It has a thin part of 15 to 0.30 mm, whereby the above objective is achieved:
A method for producing a plated molded article including a step of plating under the following processing conditions:
(A) Liquid concentration of trivalent chromium in the plating bath: 5 to 10 g / liter,
(B) Total impurity amount in the plating bath: 60 ppm or less,
(C) Bath temperature: 53-63 ° C.
(D) pH of the plating bath: 3.2 to 3.6
(E) Cathode current density: 3-5 A / dm ²
(F) Anode / cathode ratio: 1.5-2: 1.
[0011]
In one embodiment, the plating conditions further include:
(G) Rectifier: Use a rectifier that has a capacity of three times or more of the total current.
(H) Filtration capacity: The bath liquid is passed through the filtration section provided in the plating bath at least 7 rotations per hour with respect to the bath amount.
[0012]
In one embodiment, the molded product is a black color operation button of a mobile phone.
[0014]
The operation of the present invention is as follows.
[0015]
In the present invention, the plating process conditions are changed as follows for the following items.
(1) Surface irregularities (foreign matter adhesion, scratches)
Improve the filtration capacity in the plating bath and change the impurity control value of the bath. Thereby, the particles in the liquid can be made uniform (improvement of filtration accuracy), and adhesion of foreign matters can be reduced.
(2) Around plating (uniform electrodeposition)
Adjust the liquid concentration control range, reset the liquid temperature standard value, and reset the pH value.
[0016]
That is, compared with the conventional method, the metal concentration in the bath is increased to improve the throwing power. Moreover, the reaction rate is improved to improve the throwing power. Furthermore, the pH value is set high to increase the reaction rate.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0018]
As shown in FIG. 1, the thin molded product 4 of the present invention has a thin portion 3 obtained by two-color molding, a primary molded product 1 formed of ABS resin, and the primary molded product 1. And a secondary molded product 2 molded by two-color molding. The secondary molded product 2 can be formed of a transparent resin such as PC as necessary.
[0019]
The molded product 4 injection-molded in the shape of a dish has a thin portion 3, and the thickness of the thin portion is usually 0.35 mm or less, preferably 0.15 to 0.30 mm. Such a molded product can be molded by two-color molding in which the cavity and the core are reversed.
[0020]
Plating treatment is performed on the surface of the molded article having the thin wall portion thus obtained by the following steps.
(A) The molded product is washed with water, and a metal plating layer is formed on the surface thereof by electroless nickel plating (chemical plating) or copper plating.
[0021]
Electroless plating can be performed as follows.
[0022]
Etching step: The molded product is immersed in an aqueous solution of chromic anhydride and sulfuric acid at a predetermined temperature, and then washed with water to roughen the surface.
[0023]
Catalyst (catalyzer) step: A molded product is immersed in an aqueous solution of palladium chloride, stannous chloride and hydrochloric acid, and then washed with water to adsorb palladium on the surface of the molded product.
[0024]
Accelerator process:
The molded product is immersed in an aqueous solution of hydrochloric acid, washed with water, and tin adsorbed together with palladium in the catalyst process is dissolved and removed with hydrochloric acid.
[0025]
Electroless nickel plating or copper plating (chemical plating):
Immerse in a mixed solution of nickel or copper, formalin, Rossell salt, caustic soda, sodium hypophosphite, ammonia, water, etc. and wash with water. Thereby, nickel (copper) is deposited on palladium by a reduction reaction with formalin and sodium hypophosphite.
[0026]
Next, electroplating is performed on the electroless plating layer as follows.
[0027]
In the present invention, nickel plating, chromium plating, or chromium alloy plating is performed after copper plating.
(B) A copper plating layer is formed on the surface of the electroless plating layer by electroplating.
[0028]
The thickness of the copper plating layer is usually 5 μm to 15 μm.
[0029]
The copper plating conditions can be as follows.
[0030]
The molded product is immersed in a copper sulfate bath of 70 to 90 g / l of copper sulfate and 170 to 210 g / l of sulfuric acid at 10 to 30 ° C. (more preferably 20 ° C.) to obtain a cathode current density of 1 to 1. Plating at 4 A / dm ² .
(C) A nickel layer is formed on the surface of the copper plating layer by electroplating.
[0031]
A molded product is immersed in a mixed solution containing nickel sulfate, nickel chloride, boric acid, and a brightening agent, then treated under predetermined voltage and current conditions, and then washed with water to form a nickel film on the surface of the molded product.
[0032]
The water washing after the plating treatment is preferably performed by applying vibration to the water using a special device, and the liquid that has entered the gap between the primary molded product 1 and the secondary molded product 2 of the two-color molded product is completely removed. Can be kicked out.
(D) A chromium layer or a chromium alloy layer is formed on the surface of the nickel layer by electroplating.
[0033]
In the present invention, trivalent chromium plating is processed. The composition of the plating solution is, for example, chromium sulfate (trivalent), chromium acetate ( trivalent), chromium nitrate ( trivalent), chromium chloride ( trivalent) as disclosed in JP-A-2000-54157. Chromium biphosphate ( trivalent) can be used.
[0034]
Here, the silver plating conditions are as follows.
(A) Liquid concentration of trivalent chromium in the plating bath: 6 to 10 g / liter (preferably 7 to 9 g / liter),
(B) Total amount of impurities in the plating bath: 60 ppm or less (preferably 35 ppm or less),
(C) Bath temperature: 40-50 ° C (preferably 47-49 ° C),
(D) pH of the plating bath: 3.2 to 3.6 (preferably pH 3.35 to 3.45),
(E) Cathode current density: 3 to 5 A / dm ² (preferably 3.5 to 4.5 A / dm ² ),
(F) Anode / cathode ratio: 1.5-2: 1
(G) Rectifier: Use a rectifier that has a capacity that is at least three times the total current.
(H) Filtration capacity: The amount of the bath is passed through the rolling filtration section 7 times or more per hour with respect to the amount of the bath. This filtration is performed continuously. That is, the bath liquid is circulated 7 to 10 times / hour in the present invention, while the circulation rate of the bath liquid is conventionally about 2 times / hour. Further, it is preferable to use a filter (filter cloth) having a mesh size of 5 μm to 10 μm (conventionally about 50 to 100 μm).
[0035]
Moreover, it is preferable to always apply the current to the plating bath.
[0036]
In order to obtain a black molded product, only the following points are changed among the above processing conditions.
(A ′) Trivalent chromium concentration in the plating bath: 6 to 10 g / liter (preferably 6 to 9 g / liter)
(C ′) bath temperature: 53 to 63 ° C. (preferably 57 to 59 ° C.),
(D ′) Plating bath pH: 3.2 to 3.6 (preferably pH 3.45 to 3.55).
[0037]
As described above, the chromium concentration and the liquid temperature are increased by about 2%, the pH is set to a value lower by about 0.2, and the filtration capacity is set to 2.5 times or more than the manufacturer's standard plating treatment conditions. As a result, impurities can be reduced.
[0038]
【Example】
(Example 1)
The molded product after the nickel plating was subjected to trivalent chromium plating under the following plating conditions to obtain a silver portable button.
(A) Liquid concentration of trivalent chromium in the plating bath: 9 g / liter (b) Total impurity amount in the plating bath: 35 ppm or less (c) Bath temperature: 48 ° C.
(D) Plating bath pH: 3.4
(E) Cathode current density: 4.0 A / dm ²
(F) Anode / cathode ratio: 1.5: 1
(G) Rectifier: Use a rectifier having a capacity three times the total amount of current.
(H) Filtration capacity: The bath volume is continuously passed through the filtration section for 7 or more revolutions per hour with respect to the bath volume.
[0039]
As a result, a silver-colored portable button with no irregularities on the surface and good plating was obtained.
(Example 2)
The molded product after the nickel plating was subjected to trivalent chromium plating under the following plating conditions to obtain a black portable button.
(A) Liquid concentration of trivalent chromium in the plating bath: 9 g / liter (b) Total impurity amount in the plating bath: 35 ppm or less (c) Bath temperature: 58 ° C.
(D) pH of plating bath: 3.5
(E) Cathode current density: 4.0 A / dm ²
(F) Anode / cathode ratio: 1.5: 1
(G) Rectifier: Use a rectifier having a capacity three times the total amount of current.
(H) Filtration capacity: The bath volume is continuously passed through the filtration section for 7 or more revolutions per hour with respect to the bath volume.
[0040]
As a result, a black portable button having no unevenness on the surface and good plating was obtained.
(Comparative Example 1)
The molded product after the nickel plating was subjected to trivalent chromium plating under the following plating conditions to obtain a silver portable button.
(A) Liquid concentration of trivalent chromium in the plating bath: 5 g / liter (b) Total impurity amount in the plating bath: 600 ppm
(C) Bath temperature: 40 ° C
(D) pH of plating bath: 3.2
(E) Cathode current density: 7.0 A / dm ²
(F) Anode / cathode ratio: 1.5: 1
(G) Rectifier: A rectifier having a capacity that is one time the total amount of current is used.
(H) Filtration capacity: The amount of the bath is passed through the filtration unit continuously for two rotations per hour with respect to the amount of the bath.
[0041]
As a result, a silver portable button having no irregularities on the surface and poor plating was obtained.
(Comparative Example 2)
The molded product after the nickel plating was subjected to trivalent chromium plating under the following plating conditions to obtain a black portable button.
(A) Liquid concentration of trivalent chromium in the plating bath: 8 g / liter (b) Total impurity amount in the plating bath: 640 ppm or less (c) Bath temperature: 50 ° C.
(D) Plating bath pH: 3.4
(E) Cathode current density: 7.0 A / dm ²
(F) Anode / cathode ratio: 1.5: 1
(G) Rectifier: Use a rectifier having a capacity twice as large as the total amount of current.
(H) Filtration capacity: The amount of the bath is passed through the filtration unit continuously for two rotations per hour with respect to the amount of the bath.
[0042]
As a result, a black portable button with no irregularities on the surface and poor plating was obtained.
[0043]
The surface irregularities were determined by visually observing the adhesion of foreign matter, scratches, etc. at a distance of 30 cm or more, and those having a foreign matter of 0.2 mm or more were judged as rejected.
[0044]
Judgment of plating around was made by visually observing whether or not there was uniform plating and the presence or absence of discoloration, haze, etc., and those with discoloration, haze, etc. were rejected.
[0045]
【The invention's effect】
According to the present invention, a metal film having excellent corrosion resistance can be formed by surface treatment using a treatment liquid containing no hexavalent chromium, and the chromium concentration and the liquid temperature are increased by about 2% relative to the manufacturer standard, and the pH is increased. Can be reduced to about 0.2 by setting the filtration capacity to 2.5 times or more.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of one embodiment of a plated molded product obtained by the manufacturing method of the present invention.
[Explanation of symbols]
1 Primary molded product 2 Secondary molded product 3 Thin part 4 Molded product

Claims (6)

Trivalent chromium is formed on the surface of a molded product obtained by two-color molding, which comprises a primary molded product formed of ABS resin and a secondary molded product formed of polycarbonate resin inside the primary molded product. A method of manufacturing a plated molded product for processing plating,
The molded product is a button for operating a mobile phone, and the primary molded product has a thin portion with a thickness of 0.15 to 0.30 mm,
A method for producing a plated molded article including a step of plating under the following processing conditions:
(A) Trivalent chromium liquid concentration in the plating bath: 6 to 10 g / liter,
(B) Total impurity amount in the plating bath: 60 ppm or less,
(C) Bath temperature: 40-50 ° C.
(D) pH of the plating bath: 3.2 to 3.6
(E) Cathode current density: 3-5 A / dm ²
(F) Anode / cathode ratio: 1.5-2: 1. The method for producing a plated molded article according to claim 1, wherein the plating treatment condition further includes:
(G) Rectifier: Use a rectifier that has a capacity that is at least three times the total current.
(H) Filtration capacity: The bath liquid is passed through the filtration section provided in the plating bath at least 7 rotations per hour with respect to the bath amount.   The method of manufacturing a plated molded product according to claim 1 or 2, wherein the molded product is a silver color operation button of a mobile phone. Trivalent chromium is formed on the surface of a molded product obtained by two-color molding, which comprises a primary molded product formed of ABS resin and a secondary molded product formed of polycarbonate resin inside the primary molded product. A method of manufacturing a plated molded product for processing plating,
The molded product is a button for operating a mobile phone, and the primary molded product has a thin portion with a thickness of 0.15 to 0.30 mm,
A method for producing a plated molded article including a step of plating under the following processing conditions:
(A) Liquid concentration of trivalent chromium in the plating bath: 5 to 10 g / liter,
(B) Total impurity amount in the plating bath: 60 ppm or less,
(C) Bath temperature: 53-63 ° C.
(D) pH of the plating bath: 3.2 to 3.6
(E) Cathode current density: 3-5 A / dm ²
(F) Anode / cathode ratio: 1.5-2: 1. The method for producing a plated molded article according to claim 4, wherein the plating treatment condition further includes:
(G) Rectifier: Use a rectifier that has a capacity that is at least three times the total current.
(H) Filtration capacity: The bath liquid is passed through the filtration section provided in the plating bath at least 7 rotations per hour with respect to the bath amount.   The method of manufacturing a plated molded product according to claim 4 or 5, wherein the molded product is a black operation button for a mobile phone.

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