CN111032910A

CN111032910A - Method for pre-plating surface of ABS resin, method for plating surface of ABS resin, and ABS resin plated product

Info

Publication number: CN111032910A
Application number: CN201880055459.8A
Authority: CN
Inventors: 永井达夫; 山本裕都喜; 山本泰望; 桥本康男; 泉谷美代子
Original assignee: JCU Corp; Kurita Water Industries Ltd
Current assignee: JCU Corp; Kurita Water Industries Ltd
Priority date: 2017-09-01
Filing date: 2018-08-31
Publication date: 2020-04-17
Also published as: EP3677703A1; WO2019045047A1; US20200190682A1; EP3677703A4; JP2019044229A

Abstract

A processing apparatus (1) of the present invention comprises: a treatment tank (2) provided with a constant temperature heater (3) on the outer periphery; an electrolytic cell (6) connected to a pipe (4) having a circulation pump (5); and a pipe (7) for supplying the electrolytic cell (6) to the treatment tank (2). The electrolytic cell (6) is provided with an anode (6A) and a cathode (6B) each comprising a diamond electrode, and a bipolar electrode (6C) disposed between the anode and the cathode. The treatment tank (2) and the electrolytic cell (6) are filled with sulfuric acid of a predetermined concentration, and the sulfuric acid is electrolyzed by passing a predetermined current from the direct current power supply unit to the anode (6A) and the cathode (6B), thereby generating a persulfuric acid solution (S) such as peroxodisulfuric acid, which can be supplied to the treatment tank (2) via the pipe (7). The treatment apparatus (1) can be applied to a method for pretreating the surface of an ABS resin by plating, and is a method for pretreating the surface of a chromium-free and manganese-free ABS resin by plating, and can form plating which is sufficiently dense on the surface of the ABS resin.

Description

Method for pre-plating surface of ABS resin, method for plating surface of ABS resin, and ABS resin plated product

Technical Field

The present invention relates to a pretreatment method performed before plating treatment of the surface of an ABS resin. The present invention also relates to a method for plating the surface of an ABS resin, which is subjected to the pretreatment. The present invention also relates to an ABS resin plated product obtained by plating the surface of the ABS resin subjected to the pretreatment.

Background

In the portion using metal as a structural material or a member material, the portion is replaced by plastic, and advantages such as light weight, low cost, freedom of shape, and easiness in mass production are exhibited. At present, the resin composition is widely used not only for decoration but also for exterior and interior parts of automobiles, home electric appliances, and the like. In this case, the plastic surface is often plated to improve rigidity, abrasion resistance, weather resistance, heat resistance, and the like.

Since plastic is nonconductive, a metal film as a conductor needs to be formed on plastic in order to perform plating. The methods are roughly classified into dry methods such as CVD (chemical vapor deposition) and PVD (physical vapor deposition), and wet methods such as electroless nickel plating. Since the dry method is almost always a method of forming a film under vacuum and is not suitable for mass production or application to large-sized parts, a wet method has been used so far.

Among such plastic molded products, ABS resin is widely used as a main plastic replacing metal as the resin most easily plated. As the roughening treatment before the plating of the ABS resin, a chromic acid solution or a sulfuric acid solution was used for the roughening treatment. Chromic acid is represented by the chemical formula H₂CrO₄Indicating the presence of 2CrO in the etching solution as a mixed solution of the etching solution and concentrated sulfuric acid₄ ^2-+2H₃O⁺→Cr₂O₇ ^2-+3H₂And balancing O, wherein Cr is hexavalent. Hexavalent chromium is the subject of REACH regulations and RoHS directives, but is not limited by itself as it does not remain in the article. However, in recent years, attention to environmental problems has increased, and thus an environmental regulation type technique not using hexavalent chromium is strongly desired. Further, the wastewater containing Cr requires wastewater treatment such as reduction, neutralization, and coagulation and precipitation, and the precipitate also contains Cr, so that it is easy to discard the precipitate.

Here, as an environment-friendly technique that replaces chromic acid, patent document 1 proposes a method of performing etching using a mixed solution of a permanganate and an inorganic salt. Further,

patent documents

2 and 3 disclose a pretreatment method of electroless plating for roughening the surface of a plastic molded article using ozone-dissolved water.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-31513;

patent document 2: japanese patent laid-open publication No. 2002-121678;

patent document 3: japanese patent laid-open No. 2012 and 52214.

Disclosure of Invention

Problems to be solved by the invention

However, the method of etching using a mixed solution of a permanganate and an inorganic salt described in patent document 1 has a problem that the surface treatment of the ABS resin is difficult and the adhesion to metal is poor. Further, manganese (Mn) is also expected to be subject to REACH regulations and RoHS directive in the future, as with Cr, and is therefore not used. In addition, the method for the pre-plating treatment of the plastic surface described in

patent documents

2 and 3 has a problem that since the ozone decomposition rate is high, it is necessary to produce ozone water of high concentration and maintain the high concentration, and therefore, not only a large facility is required, but also treatment unevenness due to a local ozone concentration difference is likely to occur.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for pretreating an ABS resin surface with plating, which is a chromium-free and manganese-free method for pretreating an ABS resin surface with plating capable of forming plating sufficiently close to the ABS resin surface. Further, an object of the present invention is to provide a plating method which can satisfactorily adhere to the surface of the ABS resin subjected to the pretreatment method. Further, an object of the present invention is to provide an ABS resin plated product obtained by plating the surface of the ABS resin subjected to the pretreatment.

Means for solving the problems

In order to achieve the above object, the first aspect of the present invention provides a method for treating the surface of an ABS resin before plating, which comprises treating the ABS resin with a solution obtained by electrolyzing sulfuric acid (invention 1).

According to the invention (invention 1), the butadiene component on the surface of the ABS resin is dissolved by the strong oxidation action of the persulfuric acid generated by the electrolytic sulfuric acid to roughen the surface, thereby increasing the specific surface area and exposing the hydrophilic functional group, and therefore, the ABS resin after the treatment can be plated to obtain a sufficiently close plating by performing the plating treatment. In the present specification, the ABS resin includes not only an acrylonitrile-butadiene-styrene copolymer resin (ABS resin) alone but also a mixed resin of the ABS resin and another resin, specifically, a mixed resin of the ABS resin and a polycarbonate (PC resin). In particular, the PC/ABS mixed resin comprises 20-70 wt% of PC resin relative to 100 wt% of the total of ABS resin and PC resin.

In the above invention (invention 1), the sulfuric acid concentration of the solution is preferably 60 to 87% by weight (invention 2).

According to the invention (invention 2), the surface of the ABS resin is appropriately roughened by the persulfate solution obtained by electrolyzing the sulfuric acid of the above-mentioned concentration, thereby increasing the specific surface area and improving the adhesion of plating. Further, the degree of treatment of the surface of the ABS resin can be adjusted by changing the sulfuric acid concentration within the above range.

In the above inventions (inventions 1 and 2), the temperature of the treatment is preferably 50 to 80 ℃ (invention 3).

According to the invention (invention 3), the surface of the ABS resin is appropriately roughened while suppressing the decomposition of persulfuric acid, thereby increasing the specific surface area and further improving the adhesion of plating.

In the above inventions (inventions 1 to 3), the persulfuric acid concentration of the solution is preferably 3g/L or more (invention 4).

According to the invention (invention 4), the ABS resin surface can be appropriately roughened by the strong oxidation action of the persulfuric acid to increase the specific surface area and further improve the adhesion of plating.

The second aspect of the present invention provides a method for plating a surface of an ABS resin, which comprises treating the surface of the ABS resin with the method for pre-plating the surface of the ABS resin according to any one of the above-mentioned inventions (inventions 1 to 4), and then subjecting the surface of the ABS resin to electroless plating or electroplating (invention 5).

According to the invention (invention 5), since the butadiene component on the surface of the ABS resin is dissolved by the strong oxidation action of the persulfuric acid generated by the electrolytic sulfuric acid to roughen the surface and expose the hydrophilic functional group, the ABS resin after the treatment can be subjected to the plating treatment to deposit a plating such as chromium having good adhesion on the surface of the ABS resin.

The third aspect of the present invention provides an ABS resin plated product obtained by applying a plating treatment to the surface of the ABS resin according to the above-described ABS resin plating method of the invention (invention 5) (invention 6).

According to this invention (invention 6), an ABS resin plated product is obtained by plating a surface of an ABS resin with chromium or the like having good adhesion.

Effects of the invention

According to the method for plating the surface of the ABS resin of the present invention, the butadiene component on the surface of the ABS resin is dissolved by the strong oxidation of the persulfuric acid generated by the electrolytic sulfuric acid to roughen the surface, thereby increasing the specific surface area and exposing the hydrophilic functional group.

Drawings

Fig. 1 is a schematic view showing a configuration of a processing apparatus to which a plating pretreatment method for an ABS resin surface according to an embodiment of the present invention can be applied.

Detailed Description

Fig. 1 is a schematic view showing a configuration of a processing apparatus to which a plating pretreatment method for an ABS resin surface according to an embodiment of the present invention can be applied. The processing apparatus 1 in fig. 1 includes: a treatment tank 2 having a constant temperature heater 3 provided on the outer periphery thereof; an electrolytic cell 6 connected to the pipe 4 having a circulation pump 5; and a pipe 7 for supplying the electrolytic bath 6 to the treatment tank 2. The electrolytic cell 6 includes an anode 6A and a cathode 6B each made of a diamond electrode, and a bipolar electrode 6C disposed therebetween. In the treatment tank 2, a stirring mechanism such as an aeration pipe for stirring the inside of the tank may be provided as necessary.

In the treatment apparatus 1, sulfuric acid having a predetermined concentration is filled in the treatment tank 2 and the electrolytic bath 6 in an initial state, and the sulfuric acid is electrolyzed by passing a predetermined current from the dc power supply unit to the anode 6A and the cathode 6B to generate a sulfuric acid solution (hereinafter, referred to as a sulfuric acid solution in the present specification) S containing persulfuric acid (an oxidizing agent) such as peroxodisulfuric acid, and the sulfuric acid solution S can be supplied to the treatment tank 2 through the pipe 7. The persulfuric acid solution S is circulated by circulating the persulfuric acid solution S from the treatment tank 2 to the electrolytic cell 6 through the pipe 4 by the circulating pump 5. In the processing tank 2, an ABS resin plate 8 to be processed is suspended in the vertical direction.

The concentration of sulfuric acid in the persulfuric acid solution S is preferably 60 to 87 wt%, and more preferably 70 to 83 wt%. When the sulfuric acid concentration is less than 60 wt%, the sulfuric acid concentration of the obtained persulfuric acid solution S is too low, and the surface of the ABS resin plate 8 cannot be sufficiently roughened, so that the effect of improving the plating adhesion cannot be sufficiently obtained, while when the sulfuric acid concentration exceeds 87 wt%, the effect cannot be further improved, and the workability is also deteriorated, which is not preferable.

Next, a method of pretreatment for plating the surface of the ABS resin using the above-described treatment apparatus 1 will be described. First, sulfuric acid is fed into the treatment tank 2, heated by the constant temperature heater 3, supplied to the electrolytic cell 6 by the circulation pump 5, and electrolyzed by passing a predetermined current from the dc power supply unit to the electrolytic cell 6 to produce a persulfate solution S such as peroxodisulfuric acid, which is supplied to the treatment tank 2 through the pipe 7 and circulated.

In this case, the persulfuric acid solution S is preferably heated by the constant temperature heater 3 so that the temperature thereof becomes 50 to 80 ℃. When the temperature of the persulfuric acid solution S is less than 50 ℃, the surface of the ABS resin plate 8 cannot be sufficiently roughened, and thus the effect of improving the plating adhesion cannot be sufficiently obtained, while when the temperature exceeds 80 ℃, decomposition of persulfuric acid is promoted to lower the treatment efficiency.

The electrolysis of sulfuric acid in the electrolytic cell 6 may be carried out under conditions such that the concentration of persulfuric acid such as peroxodisulfuric acid produced by the electrolysis is 3g/L or more, particularly 3 to 20 g/L. When the concentration of persulfuric acid is less than 3g/L, the effect of improving the plating adhesion cannot be sufficiently obtained, while when it exceeds 20g/L, not only the above effect cannot be improved but also it is uneconomical.

When the persulfuric acid solution S in the treatment tank 2 has reached the above temperature and the persulfuric acid concentration, the surface of the ABS resin sheet 8 is treated by immersing the degreased ABS resin sheet 8 in the treatment tank 2. In this case, in order to suppress bubbles adhering when immersed in the persulfate solution S, it is preferable to perform a wet treatment on the ABS resin plate 8 in advance.

The ABS resin plate 8 is immersed in a persulfuric acid solution S in the treatment tank 2 for 5 to 20 minutes, whereby hydrophilic functional groups are exposed on the surface of the ABS resin plate 8. Thus, hydroxyl groups, carbonyl groups, aldehyde groups, and carboxyl groups of the ABS resin appear on the surface of the ABS resin. This improves the adhesion of plating in the subsequent plating treatment.

After activating the functional groups appearing on the resin surface of the ABS resin plate 8 in the above-mentioned step, neutralization, reduction treatment, conditioning treatment, and the like may be performed as necessary.

By the pretreatment method of the present embodiment described above, the surface of the ABS resin plate 8 can be etched. In the method for the pre-plating treatment according to the present embodiment, a conventionally known plating method for a resin, such as an electroless plating method or a direct plating method, can be applied thereafter.

For example, the catalyst is applied to the ABS resin plate 8 treated by the pretreatment method according to the present embodiment by the catalyst application treatment liquid. The catalyst-applying treatment solution is not particularly limited as long as it is a solution for applying a catalyst that is generally used in a plating step, but a solution containing a noble metal is preferable, a solution containing palladium is more preferable, and a palladium/tin mixed colloidal catalyst solution is particularly preferable. When these catalysts are applied to the resin surface, the liquid temperature of the catalyst application treatment liquid is preferably 10 to 60 ℃, particularly preferably 20 to 50 ℃, and the ABS resin sheet 8 may be immersed in the catalyst application treatment liquid for 1 to 20 minutes, preferably 2 to 5 minutes. The resin surface to which the catalyst has been applied in this manner is then metallized by a metal plating treatment such as electroless plating or electroplating (direct plating).

In the case of metallizing the resin surface by electroless plating, the resin surface may be further treated with an activating treatment solution containing hydrochloric acid or sulfuric acid after the catalyst is applied by using a catalyst-applying treatment solution. The concentration of hydrochloric acid or sulfuric acid in the activation treatment liquid is 0.5mol/L or more, preferably 1 to 4 mol/L. When the resin surface is treated with the activating treatment liquid, the liquid temperature of the activating treatment liquid is preferably 0 to 60 ℃, particularly preferably 30 to 45 ℃, and the ABS resin sheet 8 may be treated by being dipped therein for preferably 1 to 20 minutes, particularly preferably 2 to 5 minutes.

The ABS resin plate 8 activated with the catalyst as described above is then subjected to electroless plating. The electroless plating treatment can be performed by a conventional method using electroless plating such as a known electroless nickel plating solution, electroless copper plating solution, and electroless cobalt plating solution. Specifically, when the resin surface is plated with an electroless nickel plating solution, the ABS resin sheet 8 may be immersed in the electroless nickel plating solution having a pH of 8 to 10 and a solution temperature of 30 to 50 ℃ for 5 to 15 minutes.

In addition, when plating (direct plating) is used for metallizing the resin surface, after the catalyst is applied from the catalyst-applying treatment liquid, the resin may be further treated with an activating treatment liquid containing copper ions and having a pH of 7 or more. The source of the copper ions contained in the activation treatment liquid is not particularly limited, and examples thereof include copper sulfate. When the resin surface is treated with the activation treatment liquid, the liquid temperature of the activation treatment liquid is preferably 0 to 60 ℃, particularly preferably 30 to 50 ℃, and the ABS resin sheet 8 may be treated by being immersed therein for preferably 1 to 20 minutes, particularly preferably 2 to 50 minutes.

The ABS resin plate 8 activated by the catalyst as described above may be immersed in a common electrolytic copper plating bath such as a copper sulfate bath under normal conditions, for example, 1 to 5A/dm²And (3) treating for 2-10 minutes under the condition. Incidentally, the water washing and the hot water washing have been sufficiently performed between the respective steps so far. As described above, the surface of the ABS resin plate 8 is plated with a metal such as electroless plating or electroplating, and the surface of the metallized ABS resin plate 8 can be further plated with a metal such as electrolytic plating or electroplating, if necessaryElectroplating copper, electroplating nickel and electroplating chromium. In these metal plating, the plating may be performed so long as a coating film is obtained, and examples thereof include nickel, copper, chromium, cobalt, tin, zinc, iron, silver, gold, and alloys thereof.

Although such treatment can be continuously carried out while replacing the ABS resin sheet 8, it is preferable to continuously drive the circulation pump 5 to continuously replenish the persulfuric acid solution S from the electrolytic bath 6 to the treatment tank 2 through the pipe 7 because the persulfuric acid in the persulfuric acid solution S in the treatment tank 2 is decomposed with the treatment and the concentration of the persulfuric acid is reduced. Further, when the sulfuric acid concentration is decreased, the sulfuric acid may be appropriately supplemented to the treatment tank 2, and when the sulfuric acid concentration is increased, the water may be appropriately supplemented to the treatment tank 2. This operation can be automatically performed by providing the sulfuric acid concentration system in the treatment tank 2.

Before the pretreatment in the present embodiment as described above, the ABS resin plate 8 may be subjected to a treatment for imparting wettability as necessary. This treatment can be performed, for example, by sufficiently immersing the ABS resin sheet 8 in a wetting treatment tank to impart wettability to the surface of the resin sheet. The wet treatment tank may contain a surfactant. The surfactant is not particularly limited, and examples thereof include an amine salt type surfactant, a quaternary ammonium salt type surfactant, an amino acid type surfactant, a betaine type surfactant, a carboxylate type surfactant, a sulfonate type surfactant, a sulfate type surfactant, a phosphate type surfactant, an ether type surfactant, an ester type surfactant, a nitrogen type surfactant, and a fluorine type surfactant. One or two or more of these surfactants can be used.

The ABS resin plate 8 pretreated as described above can be subjected to electroless plating or electroplating by a usual method. This makes it possible to obtain an ABS resin plated product obtained by plating the surface of the ABS resin plate 8 with chromium or the like having good adhesion.

The plating method for the ABS resin surface according to the present invention has been described above based on the above embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made. For example, the present invention can be applied not to the batch process but to the continuous process as in the present embodiment. It is needless to say that the ABS resin sheet is not limited to a sheet as in the present embodiment, and can be applied to molded articles of various shapes.

Examples

The present invention will be described more specifically below with reference to examples and comparative examples. However, the present invention is not limited to these descriptions at all. In the following examples and comparative examples, the persulfuric acid concentration and the adhesion test were performed as follows.

< method for measuring persulfuric acid concentration >

First, the total oxidant concentration contained in the treatment liquid (the peroxysulfuric acid solution S) was measured by iodine titration. The iodine titration is carried out by adding KI to a persulfuric acid solution S to add I₂Free, titrate the I with sodium thiosulfate standard solution₂To find I₂And from the amount of I₂The oxidant concentration was determined. Then, only the hydrogen peroxide concentration of the peroxysulfuric acid solution S was determined by potassium permanganate titration, and the persulfuric acid concentration was calculated by subtracting the potassium permanganate titration value from the iodine titration value.

< plating adhesion test >

In this test, adhesion was examined by thermal shock by heating and rapidly cooling a sample, and after 40 cycles of holding the sample for 1 hour under temperature conditions of 70 ℃ and-30 ℃, i.e., a temperature difference of 100 ℃, the presence or absence of peeling, cracking, expansion, and the like on the plating surface was observed, and evaluation was performed in three stages of the following categories 1 to 3.

Classification 1: there was no peeling, cracking or wrinkling, or swelling of the plating at all.

And (4) classification 2: there was peeling, cracking or wrinkling, swelling of the plating less than 25% of the area of the sample.

And (3) classification: the plating had peeling, cracking, wrinkling, or swelling of 25% or more of the sample area.

[ example 1]

The surface treatment of the ABS resin plate 8 was performed by using the apparatus shown in fig. 1. The specifications and conditions of the treatment tank are as follows.

< treatment tank >

Volume of treatment tank 2: 40L

Dimensions of the ABS resin plate 8: 500mm x thickness 5mm

< Property of persulfuric acid solution S and surface treatment conditions >

Concentration of sulfuric acid: 75% by weight

Concentration of persulfuric acid: 10g/L

Treatment temperature: 75 deg.C

Treatment time: 15 minutes

< electrolytic cell for persulfuric acid formation 6 and electrolysis conditions >

The volume of the pool is as follows: 0.5L

Anode and cathode: diamond electrode (diameter 150mm)

Bipolar electrode material: the anode and the cathode are the same

Current density: 50A/dm²

Liquid circulation amount: 2.5L/min

Concentration of sulfuric acid: 75% by weight

Concentration of persulfuric acid: 10g/L

Treatment temperature: 75 deg.C

First, the ABS resin plate 8 was immersed in a wetting treatment tank containing a surfactant for 10 minutes, then immersed in a treatment tank 2 filled with a persulfate solution S for 10 minutes, taken out from the treatment tank 2, washed with tap water, and then subjected to electroless nickel plating through an activation step and a catalyst application step. Thereafter, chromium plating is finally performed. The treatment conditions in the plating step are shown in tables 1 and 2. Further, the plating adhesion of the chromium-plated ABS resin plate 8 was evaluated by the above-described method. The results are shown in Table 3 together with the conditions of the electrolytic sulfuric acid treatment.

TABLE 1

Trade names manufactured by 1 to 8 Jieshiyu (JCU)

TABLE 2

Trade names of 9 to 17 Jieshi products

[ examples 2 to 7]

Chromium plating was performed in the same manner as in example 1 except that the electrolytic sulfuric acid treatment conditions were changed to various settings as shown in table 3, and the adhesion of the plating was evaluated. The results are shown in Table 3 together with the conditions of the electrolytic sulfuric acid treatment.

Comparative example 1

Chromium plating was performed in the same manner as in example 1 except that a sulfuric acid solution having a sulfuric acid concentration of 75 wt% was used instead of the sulfuric acid electrolytic solution, and the adhesion of plating was evaluated. The results are shown in Table 3 together with the treatment conditions.

Comparative example 2

Chromium plating was performed in the same manner as in example 1, except that a mixed solution of sulfuric acid and hydrogen peroxide was used instead of the sulfuric acid electrolytic solution, and the adhesion of plating was evaluated. The results are shown in Table 3 together with the treatment conditions.

TABLE 3

As is clear from table 3, the surface plating treatment method using the ABS resin of the present invention can obtain excellent plating adhesion. In the method for plating a surface of an ABS resin of comparative example 2, there was a problem in that the treatment stability was long due to the consumption of hydrogen peroxide.

Description of the reference numerals

1 a processing device;

2, a treatment tank;

3, a constant temperature heater;

4, piping;

5 circulating pump;

6, an electrolytic cell;

6A anode;

a 6B cathode;

a 6C bipolar electrode;

7 a pipe;

8 ABS resin plate;

s a solution of persulfuric acid.

Claims

1. A method for treating the surface of ABS resin before plating,

the ABS resin was treated with a solution obtained by electrolyzing sulfuric acid.

2. The method for treating the ABS resin surface before plating according to claim 1, wherein,

the sulfuric acid concentration of the solution is 60-87 wt%.

3. The method for treating the ABS-based resin surface before plating according to claim 1 or 2, wherein,

the treatment temperature is 50-80 ℃.

4. The method for treating the surface of ABS resin before plating according to any of claims 1 to 3, wherein,

the persulfuric acid concentration of the solution is more than 3 g/L.

5. A method for plating the surface of an ABS resin,

the method for treating the surface of an ABS-based resin according to any one of claims 1 to 4 before plating, and then subjecting the surface of the ABS-based resin to electroless plating or electroplating.

6. An ABS resin plated product which has been subjected to plating treatment by the method for plating the surface of an ABS resin according to claim 5.