JPH06192842A - Method for coating resin formed article - Google Patents

Abstract

PURPOSE:To impart good adhesion in coating and high conductivity to a resin formed article by forming an electroless plating film with the surface resistance specified before the formed article contg. polyamide resin is coated. CONSTITUTION:A resin formed article contg. polyamide resin is etched by an etchant (hydrochloric acid, formic acid, etc.) contg. surfactant, etc. The article is then sensitized and activated by the catalyst acceleration process, etc., and the article is electroless-plated by using Ni-P, Ni-Co-P, Ni-Zn-P, etc., Ni, Cu, Pd, Pt, Au and Ag are deposited, as required, on the plating film. Consequently, a resin formed article having a nice appearance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a resin molded product which can simultaneously impart good coating adhesion to the resin molded product and high conductivity required for electrostatic coating.

[0002]

2. Description of the Related Art When electrostatically coating a resin molded product, it has been conventionally used as a primer for a base called a conductive primer in order to secure adhesion with a top coating and to obtain good throwing power in electrostatic coating. It was common to apply paint.

A conductive primer is used to obtain conductivity.
Add a conductive filler in the paint or a conductive additive,
For example, a surfactant is added. Examples of the conductive filler include carbon powder, non-metallic filler such as graphite, metallic filler such as silver, copper, nickel, tin, zinc, titanium, palladium and aluminum, fine particles such as glass, mica, plastic and carbon. It is possible to use a composite type filler plated with copper or silver.

Since these conductive primers are expensive in coating material, it is necessary to make the film thickness sufficiently thick to obtain the conductivity required for electrostatic coating, which raises the overall processing cost. There is. Furthermore, since automatic painting by an electrostatic painting machine is difficult and it is necessary to rely on human labor, it is a factor that further raises the cost.

It is also possible to obtain a conductive molded product by molding a resin containing a conductive filler mixed therein, but in order to obtain sufficiently high conductivity, a large amount of such filler is added. It is necessary to obtain a good coating appearance. Further, as described above, the cost of the conductive filler is high.

The inventors of the present invention have heretofore known Japanese Patent Laid-Open No. 1-2426.
37 and JP-A-2-181174 disclose a coating method for a polyamide resin. In the technologies related to these applications, it was possible to obtain sufficient coating adhesion, but the high electrical conductivity required for electrostatic coating is slightly insufficient in the case of simultaneous coating with metal. It was revealed.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and achieves sufficient adhesion of the coating material and adhesion at the same time when electrostatically coating a resin molded product. In addition, the present invention provides a method for coating a resin molded product, which can obtain a better coating appearance at low cost.

[0008]

The object of the present invention is to form an electroless plating film capable of obtaining a predetermined surface resistance on the surface of a resin molded product containing a polyamide resin, and then apply a top coat without applying a conductive primer. Solved by the method. In the coating method according to the present invention, the resin suitable as a resin molded product to be coated is not particularly limited, but it can be applied to many resin molded products containing a polyamide resin as a component. Particularly suitable resins are resin compositions containing polyphenylene ether resin and polyamide resin as main components, which are often used for outer panels and bumpers of automobiles. It can also be applied to a resin composition containing a polyamide resin and a polypropylene resin as main components.

As the polyphenylene ether in this case, known ones can be used, for example, poly (2,6-dimethyl-1,4-phenylene) ether and poly (2,6-).
Diethyl-1,4-phenylene) ether, poly (2-
Methyl-6-ethyl-1,4-phenylene) ether,
Poly (2-methyl-6-propyl-1,4-phenylene) ether, poly (2,6-dipropyl-1,4-phenylene) ether, poly (2-ethyl-6-propyl-1,4-phenylene) Examples thereof include ethers and copolymers of these with styrene.

Further, as the polyamide in this case, known materials can be used. For example, polycapramide (nylon 6), polyhexamethylene adipamide (nylon 6,6) polyhexamethylene sebacamide (nylon 6,10), polyundecane amide (nylon 11),
Examples thereof include polydodecanamide (nylon 12), amorphous nylon, and copolymers thereof.

The polypropylene resin is, for example, a copolymerized part composed of an isotactic propylene homopolymer having crystallinity or a copolymer composed of an ethylene ethylene propylene random copolymer having a low ethylene unit content, or propylene homopolymer. A homopolymerization part made of a polymer and an ethylene-propylene random copolymer having a relatively large content of ethylene units can be applied. In addition to these crystalline resins, it is applicable to amorphous polypropylene and is not limited to these.

[0012]

According to the coating method of the present invention, the resin molded product is subjected to the etching treatment after the usual washing.
As the mineral acid used for the etching treatment in this case, hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, chromic acid or the like can be used. As the organic acid, organic carboxylic acids such as formic acid, acetic acid and citric acid can be used.

Particularly, hydrochloric acid is desirable, and 10 to 400 ml
It is preferred to contain 1 / l hydrochloric acid (36% HCl). The surface of the resin is melted by these mineral acids, and irregularities are formed on the surface of the resin molded product, which gives close contact with the resin and the electroless plating film (painting).

In this case, the etching solution contains cations,
It preferably contains nonionic, anionic and amphoteric surfactants. Here, cationic system 0.01 to 50 g
/ L, cationic system 0.01 to 50 g / l + nonionic system 0.01 to 50 g / l. The inclusion of these surfactants prevents the redeposition of the dissolved resin.

Further, it promotes the adsorption of palladium, which becomes the catalyst nucleus of the electroless plating in the subsequent step, to the resin. Further, by including an inorganic salt in this etching solution, the effect of the surfactant is promoted. The preferred concentration is 1
~ 100 g / l. 10-60 in this etching solution
By immersing at 1 ° C. for 1 to 30 minutes, surface roughening suitable for providing an electroless plating film (painting) having good adhesion is performed.

After etching, the material is sensitized and activated. As the treatment method, which is usually used in plating of plastics, any of a catalyst-accelerator method and a sensitizer-activator method, or a palladium solution used for a polyamide resin or a through-hole substrate-a reducing solution immersion method is used. Can be used.

Although such sensitization / activation treatment can give conductivity to some extent, electroless plating is performed to further enhance the conductivity. For electroless plating, Ni-P, Ni-Co-P, Ni-Zn-P, N
i-Sn-P, Ni-Pd-P, Ni-Cu-P, Ni
-B, Cu, etc. can be used. Liquid is alkaline, neutral,
Either acid may be used. A desirable condition is that the total metal concentration in the electroless nickel plating solution is 0.1 to 10 g / l.
And preferably 0.5 to 5 g / l. The liquid is preferably alkaline.

20 to 90 ° C. in electroless nickel plating solution,
Immersion is preferably performed at 30 to 50 ° C. for 10 seconds to 20 minutes, preferably 10 seconds to 10 minutes.

The molded product obtained by such treatment has a highly conductive surface. Further, a metal having a low electric resistance can be deposited on the electroless plating film in order to enhance conductivity, if necessary. The metals that can be used are Ni, Cu, Pd, Pt, Au and Ag. As a method of attaching, either an electroless plating deposition method or a substitution deposition method may be used. By this treatment, a resin molded product having a surface property with higher conductivity can be obtained.

The resin-molded product electrolessly plated through the above-mentioned process can be left at room temperature and naturally dried, but can be heated and dried after the electroless plating treatment. As a drying condition, it is desirable to dry at 50 to 150 ° C. for 3 minutes to 20 hours.

Since the surface resistance of the resin molded product thus obtained is within a predetermined range of, for example, 10 ⁷ Ω · cm or less, it is possible to apply the intermediate coating or the top coating without coating the conductive primer. Capable of electrostatic coating. The top coating material in this case is not particularly limited, but a suitable coating material such as a melamine cross-linking type polyester polyol resin-based coating material or an acrylic urethane resin-based coating material can be used.

[0022]

EXAMPLES The contents of the present invention will be disclosed in detail below with reference to examples. In Examples 1 and 2, GTX was used as the base material.
6006 (Trademark: GE Plastics Co., Ltd.)
A resin composition containing a polyphenylene ether resin and a polyamide resin) was used.

Example 1 The above test piece was subjected to 30
Etching was performed at 10 ° C. for 10 minutes. Etching treatment liquid Hydrochloric acid (35% HCl) 270 ml / l EP-etching GL 400 ml / l (trademark: Kizai Co., Ltd.) Water balance

Then, a sensitizing treatment was carried out by immersing in a solution of 35% hydrochloric acid 50 ml / l at room temperature for 1 minute, washing with water, and then immersing at 30 ° C. for 3 minutes using the following sensitizing solution. Sensitization processing solution EP-Acti GL A solution 100 ml / l (trademark: Kizai Co., Ltd.) EP-Acti GL B solution 100 ml / l (trademark: Kizai Co., Ltd.)

After washing with water, the following activation treatment liquid was used.
An activation process was performed. Activation treatment liquid EP-Accel GL 100 ml / l (trademark: Kizai Co., Ltd.)

After washing the treatment solution with water, it is immersed in the electroless nickel plating solution shown below at 40 ° C. for the times shown in Table 1 (10 seconds, 20 seconds, 30 seconds) to obtain an electroless nickel plating film. It was Electroless nickel plating solution EP-Nyco GL A solution 100 ml / l (Trademark: Kizai Co., Ltd.) EP-Nyco GL B solution 100 ml / l (Trademark: Kizai Co., Ltd.)

The test piece thus obtained was dried with hot air at 120 ° C. for 10 minutes.

Regarding the test piece thus obtained,
The following tests were conducted to confirm the effect. (1) Surface resistance The surface resistance of the test piece was measured according to JIS K6911 "General test method for thermosetting plastics". Here, the test piece after the electroless plating treatment was repeatedly baked in a hot air oven at 160 ° C., and the surface resistance of each baking was measured. The results are shown in Table 1.

(2) Coating adhesion, coating appearance and coating thickness As a coating material, High Epico No100 (trademark: intermediate coating, manufactured by NOF CORPORATION) was applied by electrostatic coating method, left for 10 minutes, and then 140 ° C. After baking for 30 minutes in the hot air oven, the product was taken out and left at room temperature for 30 minutes. After that, Neoamilac (trademark: manufactured by Kansai Paint Co., Ltd.,
Topcoat) is applied by electrostatic coating method, left for 10 minutes, baked at 140 ° C for 30 minutes, and taken out at room temperature for 2 minutes.
After leaving for 4 hours, the following evaluation was performed.

(1) Initial adhesion The tape was peeled off in a manner suitable for the cross-cut test (100 squares at 1 mm intervals) according to JIS K5400.
Count the number of remaining coatings out of 100. (2) Secondary Adhesion Test After dipping the test piece in warm water of 40 ° C. for 10 days, the same test as the initial adhesion test was conducted. (3) Coating appearance The appearance of the coating surface was visually evaluated. (4) Coating film thickness The cross section of the coating film was observed with an electron microscope to measure the film thickness. The test results are shown in Table 1.

[0030]

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the treatment time of the electroless plating treatment was changed to 5 seconds and 60 seconds. The results are shown in Table 2.

[0032]

Example 2 Using the above test piece, etching-sensitizing treatment-activating treatment was carried out in the same manner as in Example 1, and after washing with water, the electroless copper plating solution shown below was used, and the temperature was set at 25 ° C. Soak for 2 hours,
An electroless copper plating film was obtained. Electroless copper plating solution CP-CU305 (Trademark: Kizai Co., Ltd.) Solution A 100 ml / l Solution B 100 ml / l Solution C 20 ml / l

The obtained test piece was dried at 120 ° C. for 10 minutes. The test piece thus obtained was washed with water in the same manner as in Example 1 and then treated with an activation treatment solution shown below.
An activation process was performed. Activation treatment liquid EP-Accel GL 100 ml / l (trademark: Kizai Co., Ltd.)

After washing the treatment solution with water, it is immersed in the electroless nickel plating solution shown below at 40 ° C. for the times (10 seconds, 20 seconds, 30 seconds) shown in Table 1 to obtain an electroless nickel plating film. It was Electroless nickel plating solution EP-Nyco GL A solution 100 ml / l (Trademark: Kizai Co., Ltd.) EP-Nyco GL B solution 100 ml / l (Trademark: Kizai Co., Ltd.)

The obtained test piece was dried with hot air at 120 ° C. for 10 minutes.

Regarding the test piece thus obtained,
The following tests were conducted to confirm the effect. (1) Surface resistance The surface resistance of the test piece was measured according to JIS K6911 "General test method for thermosetting plastics". Here, the test piece after the electroless plating treatment was repeatedly baked in a hot air oven at 160 ° C., and the surface resistance of each baking was measured. The results are shown in Table 1.

(2) Coating adhesion, coating appearance and coating thickness As a coating, High Epico No100 (trademark: intermediate coating manufactured by NOF CORPORATION) was coated by an electrostatic coating method, left for 10 minutes and then 140 ° C. After baking for 30 minutes in the hot air oven, the product was taken out and left at room temperature for 30 minutes. After that, Neoamilac (trademark: manufactured by Kansai Paint Co., Ltd.,
Topcoat) is applied by electrostatic coating method, left for 10 minutes, baked at 140 ° C for 30 minutes, and taken out at room temperature for 2 minutes.
After leaving for 4 hours, the following evaluation was performed.

(1) Initial Adhesion The tape was peeled off in a manner compatible with the cross-cut test (100 squares at 1 mm intervals) according to JIS K5400.
Count the number of remaining coatings out of 100. (2) Secondary Adhesion Test After dipping the test piece in warm water of 40 ° C. for 10 days, the same test as the initial adhesion test was conducted. (3) Coating appearance The appearance of the coating surface was visually evaluated. (4) Coating film thickness The cross section of the coating film was observed with an electron microscope to measure the film thickness. The test results are shown in Table 3.

[0040]

Comparative Example 2 An experiment was conducted in the same manner as in Example 2 except that the treatment time of the electroless plating treatment was changed to 10 seconds. The results are shown in Table 4.
As shown in.

[0042]

[0043]

EFFECTS OF THE INVENTION According to the method for coating a resin molded product according to the present invention, sufficient conductivity can be obtained as compared with the conventional coating method including the step of coating a conventional conductive primer, and the coating cost can be reduced. It is possible to reduce coating cost and baking cost.

When carrying out electrostatic coating,
It is necessary to ground the object to be painted and a paint to have a predetermined potential difference. Usually, it was necessary to spray a conductive coating even on the back surface of the molded product to form a conductive portion for grounding. However, in the electroless plating method, since the electroless plating film is formed on both the front and back surfaces of the molded product, it is possible to connect the ground to an arbitrary position on the back surface, and no special treatment is required.

Further, in the method of coating the conductive primer, it is difficult for the paint to wrap sufficiently to coat the paint if the resin molded product has a complicated shape. Therefore, coating unevenness is likely to occur, but the method according to the present invention for forming an electroless plating film can form a uniform coating film even in a complicated shape and does not cause coating unevenness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Amane 1015 Hodosawa, Gotemba City, Shizuoka Prefecture, Japan GE Plastics Co., Ltd. (72) Hiromichi Uohashi, 1015 Hodosawa, Gotemba City, Shizuoka Prefecture, Japan 72) Inventor Eiji Aoki 2-10-4, Fukuura, Kanazawa-ku, Yokohama, Kanagawa Prefecture, Kizai Co., Ltd. (72) Inventor, Kiyotaka Funada 2-10-4, Fukuura, Kanazawa-ku, Yokohama, Kanagawa Prefecture, Kizai Co., Ltd.

Claims (6)

[Claims] 1. A method for coating a resin molded product whose material contains a polyamide resin, characterized in that an electroless plating film capable of obtaining a surface resistance value within a predetermined range is formed prior to the coating of the coating material. How to paint the product. 2. A resin molded article is subjected to etching treatment, sensitization / activation treatment, and electroless plating treatment in this order, and then,
The method for coating a resin molded product according to claim 1, wherein coating is performed. 3. A resin molded article is subjected to etching treatment, sensitization / activation treatment, and electroless plating treatment in this order, and then,
A method for coating a resin molded product, which comprises depositing a metal having a low electric resistance on the electroless plating layer. 4. The method for coating a resin molded product according to claim 1, wherein the etching solution for the etching treatment is an aqueous solution of any one of mineral acid and / or organic acid. 5. The method for coating a resin molded product according to claim 4, wherein the etching liquid further contains either a surfactant and / or an inorganic acid. 6. Ni, Cu, Pd, Pt, Au, Ag on electroless plating
A method for coating a resin molded product according to any one of claims 1 to 5, characterized in that a metal selected from the group of (1) to (4) is applied.