JP2019203204A - Plating pretreatment method for abs resin surface, plating treatment method for abs resin surface, and abs resin-plated product - Google Patents

Abstract

To provide a plating pretreatment method for a Cr and Mn-free ABS resin surface in which plating in sufficient contact with the ABS resin surface can be formed.SOLUTION: A treatment apparatus 1 has a treatment tank 2 provided with a constant-temperature heater 3 at an outer periphery, an electrolysis cell 6 connecting with piping 4 comprising a circulation pump 5, and piping 7 for supply from the electrolysis cell 6 to the treatment tank 2. The electrolysis cell 6 internally comprises an anode 6A and a cathode 6B composed of diamond electrodes, and a bipolar electrode 6C arranged between them. The treatment tank 2 and electrolysis cell 6 are filled with a sulfuric acid of a predetermined concentration, and a predetermined current is supplied from a DC power unit to the anode 6A and cathode 6B for electrolysis of the sulphuric acid, so that a sulphuric acid solution S such as a peroxodisulfuric acid can be produced and supplied to the treatment tank 2 through the piping 7.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pretreatment method that is performed prior to plating of an ABS resin surface. The present invention also relates to a plating method for the surface of the ABS resin subjected to this pretreatment. Furthermore, the present invention relates to an ABS resin plating product obtained by plating the surface of the ABS resin subjected to this pretreatment.

  In parts where metal is used as a structural material or component material, plastics are substituted by taking advantage of advantages such as light weight, low cost, freedom of shape, and ease of mass production. At present, it is widely used not only for decoration but also for automobile exteriors, interior parts, and home appliances. At that time, in order to improve rigidity, wear resistance, weather resistance, heat resistance and the like, the plastic surface is often plated.

  Since plastic is non-conductive, it is necessary to first form a metal film as a conductor on the 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 of electroless nickel plating. Since the dry method is mostly a film formation in a vacuum state and is not suitable for mass production or application to a large part, the wet method has been adopted so far.

Among such plastic molded products, ABS-based resins are widely used as main plastics for metal replacement as the most easily plated resin. A roughening treatment using a chromic acid / sulfuric acid solution is performed as a roughening treatment as a pretreatment for plating of the ABS resin. Chromic acid is represented by the chemical formula: H ₂ CrO ₄ , and 2CrO ₄ ² + 2H ₃ O ⁺ → Cr ₂ O ₇ ² + + 3H ₂ O in an etching solution which is a mixed solution with concentrated sulfuric acid.
However, Cr is hexavalent anyway. Although hexavalent chromium is subject to REACH regulations and RoHS directives, hexavalent chromium does not remain in the product, so it is not itself regulated. However, in recent years, interest in environmental issues has increased, and there has been a strong demand for environmentally friendly technologies that do not use hexavalent chromium. In addition, the wastewater containing Cr has a problem that wastewater treatment such as reduction, neutralization, and coagulation precipitation is required, and the precipitate also contains Cr and cannot be easily discarded.

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

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

  However, the method of etching with a mixed solution of permanganate and inorganic salt described in Patent Document 1 has a problem that the surface treatment of the ABS resin is difficult and the adhesion with the metal is not good. Furthermore, manganese (Mn) is said to be subject to REACH regulations and RoHS directives in the same way as Cr in the future, and it is desirable not to use it. Moreover, in the pretreatment method for plating the plastic surface described in Patent Document 2 and Patent Document 3, since ozone has a high decomposition rate, it is necessary to produce high-concentration ozone water and maintain a high concentration. In addition to the need for large-scale equipment, there is a problem that unevenness tends to occur in the processing due to a difference in local 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-based resin surface, which can form a plating sufficiently adhered to the ABS-based resin surface. It aims at providing the plating pre-processing method of the resin surface. Another object of the present invention is to provide a plating method that adheres well to the surface of an ABS resin subjected to such a pretreatment method. A further object of the present invention is to provide an ABS resin plated product obtained by plating the surface of the ABS resin that has been pretreated.

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

  According to this invention (Invention 1), the specific surface area is increased by dissolving the butadiene component on the surface of the ABS resin by the strong oxidizing action of persulfuric acid generated by electrolyzing sulfuric acid and roughening the surface. Since the hydrophilic functional group is exposed, sufficiently adherent plating can be obtained by plating the ABS resin after this treatment. In this specification, the ABS-based resin is not limited to acrylonitrile / butadiene / styrene copolymer resin (ABS resin) alone, but is a blend resin of this ABS resin and other resins, specifically, ABS resin. And a mixed resin of polycarbonate (PC resin). In particular, the PC resin includes a PC / ABS mixed resin in which the PC resin is 20 to 70% by weight with respect to 100% by weight of the ABS resin and the PC resin in total.

  In the said invention (invention 1), it is preferable that the sulfuric acid concentration of the said solution is 60 to 87 weight% (invention 2).

  According to this invention (invention 2), the surface area of the ABS resin is suitably roughened by a persulfuric acid solution obtained by electrolyzing this concentration of sulfuric acid, thereby increasing the specific surface area and improving the adhesion of plating. it can. And the degree of the process of the ABS resin surface can be adjusted by changing the sulfuric acid concentration within the above range.

  In the said invention (invention 1 and 2), it is preferable that the temperature of the said process is 50-80 degreeC (invention 3).

  According to this invention (Invention 3), the surface area of the ABS resin is suitably roughened while suppressing the decomposition of persulfuric acid, whereby the specific surface area is increased and the adhesion of plating can be further improved.

  In the said invention (invention 1-3), it is preferable that the persulfuric acid density | concentration of the said solution is 3 g / L or more (invention 4).

  According to this invention (invention 4), the surface area of the ABS resin is suitably roughened by the strong oxidizing action of persulfuric acid, thereby increasing the specific surface area and further improving the adhesion of the plating.

  In addition, according to the second aspect of the present invention, after treatment by the plating pretreatment method for the ABS resin surface according to any of the above inventions (Inventions 1 to 4), electroless plating or electroplating is applied to the ABS resin surface. An ABS resin surface plating method is provided (Invention 5).

  According to this invention (Invention 5), the butadiene component on the surface of the ABS resin is dissolved by the strong oxidizing action of persulfuric acid generated by electrolysis of sulfuric acid, and the surface is roughened and hydrophilic functional groups are exposed. Therefore, plating such as chromium having good adhesion can be deposited on the surface of the ABS resin by plating the ABS resin after the treatment.

  Thirdly, the present invention provides an ABS-based resin-plated product that has been plated by the method for plating a surface of an ABS-based resin described in the above-mentioned invention (Invention 5) (Invention 6).

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

  According to the plating method of the ABS resin surface of the present invention, the butadiene component on the ABS resin surface is dissolved by the strong oxidizing action of persulfuric acid generated by electrolysis of sulfuric acid, and the surface is roughened. Since the surface area increases and the hydrophilic functional groups are exposed, sufficiently adhered plating can be obtained by plating the ABS resin after this treatment.

It is the schematic which shows the structure of the processing apparatus which can apply the plating pre-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 resin surface according to an embodiment of the present invention can be applied. In FIG. 1, a processing apparatus 1 includes a processing tank 2 provided with a constant temperature heater 3 on the outer periphery, an electrolytic cell 6 continuous from a pipe 4 provided with a circulation pump 5, and a pipe supplied from the electrolytic cell 6 to the processing tank 2. 7. The electrolysis cell 6 includes an anode 6A and a cathode 6B made of a diamond electrode, and a bipolar electrode 6C disposed therebetween. In addition, in the processing tank 2, you may provide stirring means, such as a diffuser tube 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, The sulfuric acid is electrolyzed to generate a sulfuric acid solution (hereinafter referred to as a persulfuric acid solution) S containing persulfuric acid (oxidant) such as peroxodisulfuric acid. 7 can be supplied to the processing tank 2. The persulfuric acid solution S is circulated from the treatment tank 2 through the pipe 4 to the electrolytic cell 6 by the circulation pump 5 so that the persulfuric acid solution S is circulated. And in the processing tank 2, the ABS type resin board 8 which is a process target is suspended in 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 sulfuric acid concentration is less than 60% by weight, the sulfuric acid concentration of the resulting persulfuric acid solution S is too thin and the surface of the ABS resin plate 8 cannot be sufficiently roughened, thereby improving the adhesion of plating. On the other hand, if it exceeds 87% by weight, not only the improvement of the effect is not obtained, but also the handleability is unfavorable.

  Next, a plating pretreatment method for the ABS resin surface using the treatment apparatus 1 as described above will be described. First, when sulfuric acid is put into 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 a predetermined current is supplied from the DC power supply unit to electrolyze the sulfuric acid. A persulfuric acid solution S such as sulfuric acid is generated, and this 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 is 50 to 80 ° C. If the temperature of the persulfuric acid solution S is less than 50 ° C., the surface of the ABS resin plate 8 cannot be sufficiently roughened, and the effect of improving the adhesion of the plating cannot be sufficiently obtained. If it exceeds, the decomposition of persulfuric acid is promoted and the treatment efficiency is lowered.

  In addition, the electrolysis of sulfuric acid in the electrolytic cell 6 may be performed under the condition that the concentration of persulfuric acid such as peroxodisulfuric acid generated by electrolysis is 3 g / L or more, particularly 3 to 20 g / L. When the concentration of persulfuric acid is less than 3 g / L, a sufficient effect of improving the adhesion of plating cannot be obtained. On the other hand, when the concentration exceeds 20 g / L, the above effect cannot be improved and it is not economical.

  When the persulfuric acid solution S in the treatment 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 treatment tank 2. At this time, in order to suppress bubbles adhering when immersed in the persulfuric acid solution S, it is preferable that the ABS-based resin plate 8 is subjected to a wet treatment in advance.

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

  After activating the functional group expressed on the surface of the ABS resin plate 8 resin in the above process, neutralization / reduction treatment, conditioner treatment, or the like may be performed as 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 pretreatment method of this embodiment can apply plating methods to conventionally well-known resin, such as an electroless plating method and a direct plating method, after that.

  For example, a catalyst is imparted to the ABS resin plate 8 treated by the pretreatment method of the present embodiment with a catalyst imparting treatment liquid. The catalyst application treatment liquid is not particularly limited as long as it is generally used for catalyst application in the plating step, but preferably contains a noble metal, more preferably contains palladium, and particularly preferably a palladium / tin mixed colloid catalyst solution. . In order to apply these catalysts to the resin surface, the temperature of the catalyst application treatment liquid is preferably 10 to 60 ° C., particularly 20 to 50 ° C., and the ABS resin plate 8 is placed here for 1 to 20 minutes, preferably 2 to What is necessary is just to immerse and process for 5 minutes. The resin surface thus provided with the catalyst is then metallized by metal plating such as electroless plating or electroplating (direct plating).

  When electroless plating is used for the metallization of the resin surface, after applying the catalyst with the catalyst application treatment solution, the treatment may be performed with an activation treatment solution containing hydrochloric acid or sulfuric acid. The concentration of hydrochloric acid or sulfuric acid in the activation treatment liquid 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 0 to 60 ° C., particularly 30 to 45 ° C., and the ABS resin plate 8 is preferably 1 to 20 here. What is necessary is just to immerse and process for 2 minutes for 2 minutes especially.

  Next, the electroless plating process is performed on the ABS resin plate 8 to which the catalyst is applied and activated as described above. The electroless plating treatment can be performed according to 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 plating the resin surface with an electroless nickel plating solution, the ABS resin plate 8 is immersed in an electroless nickel plating solution at a pH of 8 to 10 and a temperature of 30 to 50 ° C. for 5 to 15 minutes. Process.

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

The ABS-based resin plate 8 subjected to the catalyst application and activation treatment as described above is subsequently immersed in a general-purpose electrolytic copper plating bath such as a copper sulfate bath, and is subjected to normal conditions, for example, 1 to 5 A / dm. ² for ² to 10 minutes. By the way, between each process so far, we will perform sufficient water washing and hot water washing. As described above, the surface of the ABS resin plate 8 is subjected to metal plating such as electroless plating or electroplating, and the surface of the metalized ABS resin plate 8 is further subjected to various types of copper electroplating and electric as required. Nickel plating and electrochrome plating can also be applied. These metal platings only need 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 performed continuously while replacing the ABS resin plate 8, but the persulfuric acid in the persulfuric acid solution S in the treatment tank 2 is decomposed with the treatment, and the persulfuric acid concentration decreases. It is desirable that the pump 5 is continuously driven to continuously replenish the treatment tank 2 with the new persulfuric acid solution S from the electrolytic cell 6 through the pipe 7. Moreover, what is necessary is just to replenish water to the processing tank 2 suitably, when a sulfuric acid concentration falls, and to the processing tank 2 when a sulfuric acid concentration rises. A sulfuric acid concentration system can be installed in the treatment tank 2 to perform this operation automatically.

  Prior to the pretreatment of the present embodiment as described above, the ABS resin plate 8 may be subjected to a treatment for imparting wettability as necessary. This treatment may be performed, for example, by sufficiently immersing the ABS resin plate 8 in a wet treatment tank and imparting wettability to the resin substrate surface. Further, a surfactant may be contained in the wet treatment tank. Although it does not specifically limit as surfactant, For example, amine salt type surfactant, quaternary amine salt type surfactant, amino acid type surfactant, betaine type surfactant, carboxylate type surfactant, Sulfonate-type surfactant, sulfate ester-type surfactant, phosphate ester-type surfactant, ether-type surfactant, ester-type surfactant, nitrogen-containing surfactant, fluorine-containing surfactant, etc. Can be used. These surfactants can be used alone or in combination of two or more.

  The ABS resin plate 8 that has been pretreated in this manner can be subjected to electroless plating or electroplating by an ordinary method. As a result, an ABS resin plated product in which the surface of the ABS resin plate 8 is plated with chromium or the like having good adhesion can be obtained.

  As mentioned above, although the plating method of the ABS type resin surface of this invention has been demonstrated based on the said embodiment, this invention is not limited to the said Example, A various deformation | transformation implementation is possible. For example, the present invention can be applied not only to batch processing as in the present embodiment but also to continuous processing. Needless to say, the ABS resin plate is applicable not only to the plate as in the present embodiment but also to molded products having various shapes.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited by these descriptions. In the following examples and comparative examples, the persulfuric acid concentration measurement and the adhesion test were performed as follows.

<Persulfuric acid concentration measurement method>
First, the total oxidant concentration contained in the treatment liquid (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 Is what you want. Next, only the hydrogen peroxide concentration in the persulfuric acid solution S was determined by titration with potassium permanganate, 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 by heating and quenching the sample. After carrying out 40 cycles at 70 ° C. and −30 ° C., that is, at a temperature difference of 100 ° C. for 1 hour, peeling of the plating surface, Observe the presence or absence of cracks, blisters, etc., and evaluate in three stages from classification 1 to 3 below.
Classification 1: No peeling of plating, cracks, wrinkles, or blisters.
Classification 2: Plating peeling, cracks, wrinkles, and blisters are present in less than 25% of the sample area.
Classification 3: Plating peeling, cracks, wrinkles and blisters are present in 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: 40L
ABS resin plate 8 size: 500 mm × 500 mm × thickness 5 mm
<Properties and surface treatment conditions of persulfuric acid solution S>
Sulfuric acid concentration: 75% by weight
Persulfuric acid concentration: 10 g / L
Processing temperature: 75 ° C
Treatment time: 15 minutes <Electrolytic cell 6 for persulfuric acid production and electrolysis conditions>
Cell volume: 0.5L
Anode and cathode: Diamond electrode (diameter 150mm)
Bipolar electrode material: Same as anode and cathode Current density: 50 A / dm ²
Liquid circulation rate: 2.5 L / min
Sulfuric acid concentration: 75% by weight
Persulfuric acid concentration: 10 g / L
Processing temperature: 75 ° C

  First, the ABS resin plate 8 is immersed for 10 minutes in a wet processing tank containing a surfactant, and then immersed for 10 minutes in the processing tank 2 filled with the persulfuric acid solution S. After washing with water, electroless nickel plating was performed through an activation step and a catalyst application step. Finally, chrome plating was applied. Table 1 and Table 2 show the processing conditions of the plating step. The plating adhesion of the chromium-plated ABS resin plate 8 was evaluated by the above method. The results are shown in Table 3 together with the 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 of the electrolytic sulfuric acid treatment conditions were changed as shown in Table 3, and the adhesion of the plating was evaluated. The results are shown in Table 3 together with the 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]
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 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 is apparent from Table 3, according to the plating treatment method for the surface of the ABS resin of the present invention, it can be seen that excellent plating adhesion can be obtained. In addition, in the plating method for the surface of the ABS resin of Comparative Example 2, there was a problem in the long-term stability of the treatment due to consumption of hydrogen peroxide.

DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Processing tank 3 Constant temperature heater 4 Piping 5 Circulating pump 6 Electrolytic cell 6A Anode 6B Cathode 6C Bipolar electrode 7 Piping 8 ABS resin board S Persulfuric acid solution

Claims (6)

  A plating pretreatment method for the surface of an ABS resin, wherein the ABS resin is treated with a solution obtained by electrolyzing sulfuric acid.   The plating pretreatment method for an ABS resin surface according to claim 1, wherein the sulfuric acid concentration of the solution is 60 to 87% by weight.   The plating pretreatment method for an ABS resin surface according to claim 1 or 2, wherein the temperature of the treatment is 50 to 80 ° C.   The plating pretreatment method for the ABS resin surface according to any one of claims 1 to 3, wherein the solution has a persulfuric acid concentration of 3 g / L or more.   A plating treatment method for an ABS resin surface, wherein the ABS resin surface is subjected to electroless plating or electroplating after being treated by the pretreatment method for plating an ABS resin surface according to any one of claims 1 to 4.   An ABS resin-plated product, which is plated by the method for plating the ABS resin surface according to claim 5.

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