WO2019045047A1

WO2019045047A1 - Plating pretreatment method for abs resin surface, plating treatment method for abs resin surface, and abs resin plated product

Info

Publication number: WO2019045047A1
Application number: PCT/JP2018/032342
Authority: WO
Inventors: 永井　達夫; 裕都喜山本; 泰望山本; 康男橋本; 美代子泉谷
Original assignee: 栗田工業株式会社; 株式会社Ｊｃｕ
Priority date: 2017-09-01
Filing date: 2018-08-31
Publication date: 2019-03-07
Also published as: EP3677703A1; EP3677703A4; CN111032910A; US20200190682A1; JP2019044229A

Abstract

A treatment device 1 has: a treatment tank 2 provided with a constant temperature heater 3 on the outer periphery; an electrolytic cell 6 continuing from a pipe 4 provided with a circulation pump 5; and a pipe 7 for supply to the treatment tank 2 from the electrolytic cell 6. Within the electrolytic cell 6 are provided a positive electrode 6A and a negative electrode 6B formed from diamond electrodes and a bipolar electrode 6C disposed between the two. The treatment tank 2 and the electrolytic cell 6 are filled with a prescribed concentration of sulfuric acid. The treatment device is configured such that a persulfate solution S such as peroxydisulfuric acid is generated by electrolysis of the sulfuric acid by making a prescribed current flow from a direct current power supply unit to the positive electrode 6A and the negative electrode 6B, and this persulfate solution S can be supplied to the treatment tank 2 via the pipe 7. A plating pretreatment method for Cr and Mn-free ABS resin surfaces that can form plating sufficiently adhering to an ABS resin surface can be applied to this treatment device 1.

Description

Pre-plating treatment method for ABS resin surface, plating method for ABS resin surface, and ABS resin-plated product

The present invention relates to a pretreatment method performed prior to plating of an ABS-based resin surface. The present invention also relates to a plating treatment method of the surface of the ABS-based resin which has been subjected to this pretreatment. Furthermore, the present invention relates to an ABS-based resin plated product obtained by plating the surface of the ABS-based resin subjected to the pretreatment.

In areas where metal is used as a structural material or component material, plastics are being replaced by taking advantage of weight reduction, cost reduction, freedom of shape, ease of mass production, and the like. At present, it is widely used not only for decoration but also for exterior and interior parts of automobiles, home appliances, and the like. At that time, in order to improve the rigidity, the abrasion resistance, the weather resistance, the heat resistance and the like, the plastic surface is often plated.

Since plastic is nonconductive, it is necessary to first form a metal film on the plastic to be a conductor in order to perform plating. The methods can be broadly classified into dry methods such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and wet methods of electroless nickel plating. Since the dry method is mostly film formation in a vacuum state and is not suitable for mass production or application to large parts, the wet method has been adopted so far.

Among such plastic molded products, an ABS-based resin is widely used as a resin that is most easily plated and as a main plastic for metal substitution. A surface roughening treatment with a chromic acid / sulfuric acid solution is performed for the surface roughening treatment as the plating pretreatment of the ABS resin. Chromic acid is represented by the chemical formula: H ₂ CrO ₄ , and in the etching solution which is a mixed solution with concentrated sulfuric acid, 2CrO ₄ ^2- + 2H ₃ O ⁺ → Cr ₂ O ₇ ^2- + 3H ₂ O
Although Cr's equilibrium exists, Cr is in any case hexavalent. Although hexavalent chromium is subject to the REACH regulations and the RoHS directive, it is not restricted by itself because hexavalent chromium does not remain in the product. However, in recent years there has been a growing interest in environmental issues and there is a strong demand for environmentally friendly technologies that do not use hexavalent chromium. In addition, waste water containing Cr requires waste water treatment such as reduction, neutralization, coagulation sedimentation, etc., and the precipitate also contains Cr, so that it can not be easily discarded.

Therefore, as an environment-friendly technology that replaces chromic acid, Patent Document 1 proposes etching with a mixed solution of permanganate and an inorganic salt. Further, Patent Document 2 and Patent Document 3 disclose a pretreatment method of electroless plating in which the surface of a plastic molded product is roughened using ozone-dissolved water.

JP 2008-31513A JP 2002-121678 A JP 2012-52214 A

However, in the method of etching with a mixed solution of permanganate and inorganic salt described in Patent Document 1, there is a problem that surface treatment of ABS resin is difficult and adhesion with metal is not good. Furthermore, manganese (Mn) is also said to be subject to the REACH regulation and the RoHS directive in the same manner as Cr in the future, and it is desirable not to use it. In addition, in the method for pre-plating a plastic surface described in Patent Document 2 and Patent Document 3, since ozone has a high decomposition rate, high concentration ozone water must be produced and high concentration maintained. Not only large-scale equipment is required, but there is also a problem that unevenness in processing is likely to occur due to local differences in ozone concentration.

The present invention has been made in view of the above problems, and is a plating pretreatment method for a chromium and manganese free ABS resin surface, which is capable of forming a plating sufficiently in contact with the ABS resin surface. It aims at providing the plating pretreatment method of the resin surface. Another object of the present invention is to provide a plating method which adheres well to the surface of an ABS resin to which such pretreatment method has been applied. Another object of the present invention is to provide an ABS-based resin plated product obtained by plating on the surface of the ABS-based resin which has been subjected to this pretreatment.

In order to achieve the above object, the present invention first provides a method for pre-plating a surface of an ABS-based resin, wherein the ABS-based resin is treated with a solution obtained by electrolyzing sulfuric acid (Invention 1).

According to this invention (Invention 1), the butadiene component of the surface of the ABS resin is dissolved by the strong oxidizing action of the persulfuric acid generated by electrolyzing sulfuric acid to roughen the surface, and the specific surface area is increased. Since the hydrophilic functional group is exposed, plating can be performed on the ABS-based resin after this treatment to obtain sufficiently close plating. In the present specification, an ABS-based resin refers not only to acrylonitrile-butadiene-styrene copolymer resin (ABS resin) alone, but also to a blend resin of this ABS resin and another resin, specifically an ABS resin. And polycarbonate (PC resin) mixed resin. In particular, PC resin contains 20 to 70% by weight of PC / ABS mixed resin with respect to 100% by weight in 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 this invention (Invention 2), the specific surface area is increased by suitably roughening the surface of the ABS-based resin with a persulfuric acid solution obtained by electrolyzing sulfuric acid at this concentration, and the adhesion of plating is improved. it can. Then, by varying the concentration of sulfuric acid within the above range, the degree of treatment of the surface of the ABS-based resin can be adjusted.

In the above inventions (Inventions 1 and 2), the temperature of the treatment is preferably 50 to 80 ° C. (Invention 3).

According to this invention (Invention 3), the specific surface area can be increased by appropriately roughening the surface of the ABS-based resin while suppressing the decomposition of the persulfuric acid, and the adhesion of the plating can be further improved.

In the above inventions (Inventions 1 to 3), the persulfate concentration of the solution is preferably 3 g / L or more (Invention 4).

According to this invention (Invention 4), the specific surface area can be increased by suitably roughening the surface of the ABS-based resin by the strong oxidizing action of persulfuric acid, and the adhesion of plating can be further improved.

Second, according to the present invention, after the plating pretreatment method of the ABS resin surface according to any of the above inventions (Inventions 1 to 4), electroless plating or electroplating is performed on the ABS resin surface. The plating method for ABS resin surface is provided (Invention 5).

According to this invention (Invention 5), the butadiene component on the surface of the ABS-based resin is dissolved by the strong oxidizing action of the persulfuric acid generated by electrolyzing sulfuric acid to roughen the surface and at the same time the hydrophilic functional group is exposed. Since plating is performed on the ABS resin after this treatment, plating of chromium or the like with good adhesion can be deposited on the surface of the ABS resin.

Furthermore, the present invention thirdly provides an ABS-based resin plated product (invention 6), which is plated by the plating method of the surface of the ABS-based resin described in the above invention (Invention 5).

According to this invention (invention 6), it is an ABS resin-plated product in which the surface of the ABS resin is plated with chromium or the like with good adhesion.

According to the plating method of the present invention on the surface of ABS resin, the butadiene component on the surface of ABS resin is dissolved by the strong oxidizing action of the persulfuric acid generated by electrolyzing sulfuric acid, thereby roughening the surface. Since the surface area is increased and the hydrophilic functional group is exposed, plating can be performed on the ABS-based resin after this treatment to obtain sufficiently close plating.

It is the schematic which shows the structure of the processing apparatus which can apply the pre-plating processing method of the ABS-type resin surface by one Embodiment of this invention.

FIG. 1 shows a processing apparatus to which a plating pretreatment method for an ABS-based resin surface according to an embodiment of the present invention can be applied. In FIG. 1, the processing apparatus 1 includes an electrolytic cell 6 continuous from a processing tank 2 provided with a constant temperature heater 3 on the outer periphery thereof, a pipe 4 provided with a circulating pump 5, and a pipe supplying the processing cell 2 from the electrolytic cell 6. And 7. The electrolysis cell 6 is provided with an anode 6A and a cathode 6B formed of diamond electrodes, and a bipolar electrode 6C disposed between the two. In addition, in the processing tank 2, you may provide stirring means, such as an aeration pipe for stirring the inside of a tank as needed.

In such a processing apparatus 1, the processing tank 2 and the electrolytic cell 6 are filled with sulfuric acid having a predetermined concentration in the initial state, and a predetermined current is supplied to the anode 6A and the cathode 6B from the DC power supply unit. A sulfuric acid solution (hereinafter referred to as a persulfuric acid solution in the present specification) S containing persulfuric acid (oxidizing agent) such as peroxodisulfuric acid is produced by electrolyzing sulfuric acid, and the persulfuric acid solution S is It can be supplied to the processing tank 2 via 7. The persulfuric acid solution S is configured to be circulated by circulating the persulfuric acid solution S from the treatment tank 2 to the electrolytic cell 6 by the circulation pump 5 via the pipe 4. And in the processing tank 2, the ABS-type resin board 8 which is a process target is suspended by the up-down direction.

The persulfuric acid solution S preferably has a sulfuric acid concentration of 60 to 87% by weight, particularly 70 to 83% by weight. If the concentration of sulfuric acid is less than 60% by weight, the concentration of sulfuric acid in the obtained persulfuric acid solution S is too thin to roughen the surface of the ABS-based resin plate 8 sufficiently, thereby improving the adhesion of plating. However, even if it exceeds 87% by weight, no further improvement of the effect can not be obtained, and the handleability is unfavorably deteriorated.

Next, a plating pretreatment method of the ABS resin surface using the processing apparatus 1 as described above will be described. First, when sulfuric acid is put in the treatment tank 2 and heated by the constant temperature heater 3, it is supplied to the electrolytic cell 6 by the circulation pump 5 and supplied with a predetermined current from the DC power supply unit to electrolyze sulfuric acid. A persulfuric acid solution S such as sulfuric acid is generated, and the persulfuric acid solution S is supplied to the treatment tank 2 via the pipe 7 and circulated.

At this time, it is preferable to heat by the constant temperature heater 3 so that the temperature of the persulfuric acid solution S becomes 50 to 80.degree. When the temperature of the persulfuric acid solution S is less than 50 ° C., the surface of the ABS-based resin plate 8 can not be roughened sufficiently, and while the effect of improving the adhesion of plating can not be sufficiently obtained, 80 ° C. When it exceeds, decomposition of persulfate is promoted and processing efficiency is reduced.

The electrolysis of sulfuric acid in the electrolytic cell 6 may be performed under conditions such that the concentration of persulfuric acid such as peroxodisulfuric acid generated by the electrolysis is 3 g / L or more, particularly 3 to 20 g / L. If the persulfate concentration is less than 3 g / L, sufficient improvement in the adhesion of the plating can not be obtained. If the concentration is more than 20 g / L, the above effect can not be improved and it is not economical.

When the persulfuric acid solution S in the processing tank 2 reaches the above-described temperature and persulfuric acid concentration, the surface of the ABS resin sheet 8 is treated by immersing the degreased ABS resin sheet 8 in the processing tank 2. At this time, in order to suppress air bubbles attached when immersed in the persulfuric acid solution S, the ABS resin plate 8 is preferably subjected to a wet treatment in advance.

By immersing the ABS-based resin plate 8 in the persulfuric acid solution S in the processing tank 2 for 5 to 20 minutes, hydrophilic functional groups are exposed on the surface of the ABS-based resin plate 8. Thereby, the hydroxyl group, the carbonyl group, the aldehyde group and the carboxyl group of the ABS resin appear on the surface of the ABS resin. By these, the adhesiveness of plating can be improved in subsequent plating processes.

After activating the functional group expressed on the resin surface of the ABS-based resin plate 8 in the above process, neutralization / reduction treatment, conditioner treatment, etc. may be performed if necessary.

The surface of the ABS resin plate 8 can be etched by the pretreatment method of the present embodiment described above. And the plating pre-processing method of this embodiment can apply the plating method to conventionally well-known resin, such as an electroless plating method and direct plating method, after that.

For example, a catalyst is applied to the ABS resin plate 8 treated by the pretreatment method of the present embodiment using a catalyst application treatment solution. The treatment liquid for applying a catalyst is not particularly limited as long as it is generally used for applying a catalyst in a plating step, but one containing a noble metal is preferable, one containing palladium is more preferable, and a mixed palladium / tin catalyst solution is particularly preferable. . In order to apply these catalysts to the resin surface, the temperature of the catalyst application treatment solution is preferably 10 to 60 ° C., particularly 20 to 50 ° C., and the ABS resin plate 8 is used for 1 to 20 minutes, preferably 2 to 20 minutes. It may be treated by immersion for 5 minutes. The resin surface to which the catalyst has been applied in this manner is then metallized on the resin surface by metal plating such as electroless plating and electroplating (direct plating).

When electroless plating is used to metallize the resin surface, the catalyst may be applied with a catalyst application treatment solution and then treated with an activation treatment solution containing hydrochloric acid or sulfuric acid. The concentration of hydrochloric acid or sulfuric acid in this activation treatment solution is 0.5 mol / L or more, preferably 1 to 4 mol / L. In order to treat the resin surface with these activation treatment liquids, the liquid temperature of the activation treatment liquid is preferably set to 0 to 60 ° C., particularly 30 to 45 ° C., and the ABS resin plate 8 is preferably 1 to 20 here. Immersion treatment may be carried out for a minute, especially for 2 to 5 minutes.

Next, electroless plating is performed on the ABS-based resin plate 8 to which the catalyst has been applied and activated as described above. The electroless plating treatment can be carried out according to a conventional method using electroless plating such as known electroless nickel plating solution, electroless copper plating solution, electroless cobalt plating solution and the like. Specifically, when plating the resin surface with an electroless nickel plating solution, the ABS resin plate 8 is immersed in the electroless nickel plating solution with a pH of 8 to 10 and a temperature of 30 to 50 ° C. for 5 to 15 minutes. You may do it.

When electroplating (direct plating) is used to metallize the resin surface, after applying a catalyst with a catalyst application treatment solution, treatment is further performed with a pH 7 or more activation treatment solution containing copper ions. You may go. The origin of the copper ion contained in this activation treatment solution is not particularly limited, and examples thereof include copper sulfate. In order to treat the resin surface with the activation treatment liquid, the liquid temperature of the activation treatment liquid is preferably set to 0 to 60 ° C., particularly 30 to 50 ° C., and the ABS resin plate 8 is preferably used here for 1 to 20 minutes. In particular, it may be treated by immersion for 2 to 50 minutes.

The ABS resin plate 8 subjected to the catalyst application and activation treatment as described above is subsequently immersed in a general-purpose copper electroplating bath such as a copper sulfate bath under ordinary conditions, for example, 1 to 5 A / dm. ² may be treated for 2 to 10 minutes. By the way, it is decided to carry out sufficient water washing and hot water washing between each process so far. As described above, the surface of the ABS resin plate 8 is plated with metal such as electroless plating or electroplating, and the surface of the metallized ABS resin plate 8 is further subjected to various kinds of electric copper plating or electricity as required. It is also possible to apply nickel plating or electrochromic plating. The metal plating should just be able to obtain a film as plating, and examples thereof include nickel, copper, chromium, cobalt, tin, zinc, iron, silver, gold and alloys thereof.

Such treatment may be continuously performed while replacing the ABS resin plate 8, but the persulfuric acid of the persulfuric acid solution S in the processing tank 2 is decomposed with the processing, and the persulfuric acid concentration is reduced. It is desirable to continuously drive the pump 5 to continuously replenish the processing tank 2 with fresh persulfate solution S from the electrolytic cell 6 through the pipe 7. Further, when the concentration of sulfuric acid decreases, the processing tank 2 may be appropriately supplemented with sulfuric acid, and when the concentration of sulfuric acid increases, the processing tank 2 may be appropriately supplemented with water. A sulfuric acid concentration system can be installed in the processing tank 2 and this operation can be performed automatically.

In addition, you may perform the process which provides wettability to the ABS-type resin board 8 as needed prior to the pre-processing of this embodiment which was mentioned above. This treatment may be performed, for example, by sufficiently immersing the ABS resin plate 8 in a wet treatment tank to impart wettability to the surface of the resin substrate. In addition, the wetting treatment tank may contain a surfactant. The surfactant is not particularly limited. For example, an amine salt surfactant, a quaternary amine salt surfactant, an amino acid surfactant, a betaine surfactant, a carboxylate surfactant, Sulfonate surfactants, sulfate ester surfactants, phosphate surfactants, ether surfactants, ester surfactants, nitrogen-containing surfactants, fluorine-containing surfactants, etc. Can be used. These surfactants can be used alone or in combination of two or more.

Electroless plating or electroplating can be applied to the ABS-based resin plate 8 thus pretreated by a conventional method. As a result, it is possible to obtain an ABS-based resin plated product in which the surface of the ABS-based resin plate 8 is plated with chromium or the like having good adhesion.

As mentioned above, although the plating processing method of the ABS system resin surface of the present invention was explained based on the above-mentioned embodiment, the present invention is not limited to the above-mentioned example, and various modification implementation is possible. For example, it is applicable not only to batch processing like this embodiment but to continuous processing. Further, it is needless to say that the ABS-based resin plate is applicable not only to the plate as in the present embodiment but also to molded articles of various shapes.

The present invention will be described more specifically by showing Examples and Comparative Examples below. However, the present invention is not limited at all by these descriptions. In the following examples and comparative examples, the persulfate concentration measurement and the adhesion test were performed as follows.

<Method for measuring persulfate concentration>
First, the total oxidizing agent concentration contained in the treatment solution (persulfuric acid solution S) is measured by iodine titration. And the iodometric titration, persulfate solution S added KI to release I _2, to determine the amount of I ₂ was titrated the I ₂ with sodium thiosulfate standard solution, oxidizing agent concentration from the amount of the I ₂ Seeks Next, only the hydrogen peroxide concentration of the persulfate solution S was determined by potassium permanganate titration, and the persulfate concentration was calculated by subtracting the potassium permanganate titration value from the iodine titration value.

<Plating adhesion test>
In this test, the adhesion is examined by thermal shock of heating and quenching the sample, and peeling of the plated surface is performed after 70 cycles and -30 ° C, that is, a temperature difference of 100 ° C is maintained for 1 hour for 40 cycles. The situation such as the presence or absence of a crack, swelling, etc. is observed and it evaluates in three steps from the following classification 1-3.
Category 1: There is no peeling, cracking, wrinkling or swelling of plating.
Category 2: Peeling, cracks, wrinkles and blisters of less than 25% of the sample area.
Category 3: Plating peeling, cracks, wrinkles, and blisters 25% or more of the sample area.

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

<Treatment tank>
Volume of treatment tank 2: 40 L
Size of ABS resin plate 8: 500 mm × 500 mm × thickness 5 mm
<Properties of persulfate solution S and surface treatment conditions>
Sulfuric acid concentration: 75% by weight
Persulfate concentration: 10 g / L
Processing temperature: 75 ° C
Treatment time: 15 minutes <electrolysis cell 6 for generating persulfate and electrolysis conditions>
Cell volume: 0.5 L
Anode and cathode: Diamond electrode (diameter 150 mm)
Bipolar electrode material: same as anode and cathode Current density: 50A / dm ²
Liquid circulation rate: 2.5 L / min
Sulfuric acid concentration: 75% by weight
Persulfate concentration: 10 g / L
Processing temperature: 75 ° C

First, the ABS resin plate 8 is immersed for 10 minutes in a wetting treatment tank containing a surfactant, and then immersed for 10 minutes in the treatment tank 2 filled with the persulfuric acid solution S, and then removed from the treatment tank 2 After washing with water, electroless nickel plating was applied through an activation step and a catalyst application step. Thereafter, chromium plating was finally performed. The processing conditions of the plating step are shown in Tables 1 and 2. Then, the adhesion of the plating of the chromium-plated ABS-based resin plate 8 was evaluated by the above method. The results are shown in Table 3 together with electrolytic sulfuric acid treatment conditions.

[Examples 2 to 7]
Chromium plating was performed in the same manner as in Example 1 except that various settings were changed as shown in Table 3 for electrolytic sulfuric acid treatment conditions, and the adhesion of the plating was evaluated. The results are shown in Table 3 together with electrolytic sulfuric acid treatment conditions.

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% by weight was used instead of the electrolytic sulfuric acid solution, and the adhesion of the plating was evaluated. The results are shown in Table 3 together with the processing conditions.

Comparative Example 2
Chrome 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 electrolytic sulfuric acid solution, and the adhesion of the plating was evaluated. The results are shown in Table 3 together with the processing conditions.

As apparent from Table 3, according to the plating treatment method of the surface of the ABS-based resin of the present invention, it is understood that excellent plating adhesion can be obtained. In addition, in the plating processing method of the surface of the ABS-type resin of the comparative example 2, there existed a problem in the long-term stability of a process by consumption of hydrogen peroxide.

1 processing apparatus 2 processing tank 3 constant temperature heater 4 piping 5 circulation pump 6 electrolysis cell 6A anode 6B cathode 6C bipolar electrode 7 piping 8 ABS resin plate S persulfate solution

Claims

A plating pretreatment method of ABS resin surface, wherein ABS resin is treated with a solution obtained by electrolyzing sulfuric acid.
The method according to claim 1, wherein the concentration of sulfuric acid in the solution is 60 to 87 wt%.
The plating pretreatment method according to claim 1 or 2, wherein the temperature of the treatment is 50 to 80 属 C.
The plating pretreatment method of ABS resin surface according to any one of claims 1 to 3, wherein the persulfate concentration of the solution is 3 g / L or more.
A plating treatment method of ABS resin surface, wherein electroless plating or electroplating is performed on the ABS resin surface after treating the ABS resin surface by the plating pretreatment method according to any one of claims 1 to 4.
An ABS resin-plated product, which has been plated by the plating method of ABS resin surface according to claim 5.