JPH04202336A - Method for coating resin molded product - Google Patents

Abstract

PURPOSE:To simplify resin molded product coating through enabling direct coating without the need for primer application, by treating a resin molded product with a surfactant containing a specific composition. CONSTITUTION:A resin molded product is treated with a surfactant containing, as active ingredient, >=30wt.% of a composition of structural formula of one of formulas I-IV (R1 is 34C or 51C alkyl of dimer or trimer acid produced by the polymerization of unsaturated fatty acid, or alkyl of fatty acid, as dimer acid, having structure of monocyclic form of formula V or noncyclic form of formula VI; R2 and R3 are each 1-3C alkyl, etc.; R4 is 1-2C alkyl, benzyl, etc.; n is 1-10; X<-> is Cl<->, Br<->, NO, etc.; A is CH2CH2, etc.; B is OH, NH2, etc.). Thence, this molded product is put to coating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for painting resin molded articles, particularly automobile bodies, bumpers, etc., which require treatment for seizure.

[Conventional technology]

In recent years, in order to meet the demands for lighter automobiles and lower manufacturing costs, resin molded products are increasingly being used for bodies and bumpers instead of conventional metal ones. For example, materials made of polyphenylene ether resin and polyamide resin are in practical use as resins for molding fenders and bumpers. These resin molded products have the characteristic that they can be painted and baked simultaneously with metal members used in other parts. However, these resin molded products have lower conductivity than metals. Therefore, before electrostatically painting the entire car, a conductive primer is applied to the resin molded product in order to impart conductivity and improve adhesion with the intermediate coat or top coat. Pretreatment was required. However, the conductive primer itself is expensive, and processing such as painting and baking is complicated, resulting in higher manufacturing costs than a metal body.

Therefore, the present inventors disclosed in Japanese Patent Application Laid-Open No. 2-187174 a method for painting resin molded products at low cost.

However, this method has the disadvantage that if the paint is applied and baked in one direction, the surface resistance increases, and the paint coverage cannot be obtained by electrostatic painting, and for example, recoating is not possible.

[Problems to be solved by the present invention]

An object of the present invention is to provide a simple and effective coating method for resin molded products that does not require primer application.

[Means for Solving the Problem] The problem of the present invention is to solve the problem by using a composition described in the claims, that is, a composition represented by any one of the structural formulas (I) to (VIII) below as an active ingredient. A method for painting a resin molded article, which comprises treating the resin molded article with a surfactant containing 30% by weight or more, and then painting without applying a primer. -or-CH,
CH-3 [where, B knee 0H5-NHz, -Nl
'1OCRo, -00CROR,: c, ~C2□ alkyl group] Here, R,, Rs: C1, and C5
The alkyl group of dimer and trimer acids produced by polymerization of unsaturated fatty acids in I, monocyclic form where CH=CI(CCHL) 7COQH as dimer acid.

CH:+(CHz)*(Jl(CHz)tcOO)
1CHx(CHz)qcH=c(CHz)7cOO
Acyclic form that is H.

Bicyclic which is.

Alkyl groups from fatty acids having the respective structures of Rz, l'h, Rb, Rv: Cr-C3 alkyl groups and/or -(Do), yL)I polyalkylene glycol groups (n= 1-10).

Ra: C, ~C2 alkyl group or benzyl group or -(DO))l hydroxyalkyl group or -
CHzCOOC,, Hzw+1 (n=1 to 3) acetate group.

X: Halogen group such as C1 or Br -05O3C? IH
zfl+1 (n=1-2) monoalkyl sulfate group, No
3-, SO,-.

Mineral acid of H2PO4-, C,l (2% ten, C00H (n=
1 to 18) or an organic acid having a -COOH group.

Re: 4) 1zCOO, -(CHz) S03
(n=1 to 3).

Materials suitable for the resin molded article to be coated in the coating method according to the present invention are not particularly limited, but many resins containing polyamide resin as a component can be used. Suitable examples include resin compositions containing polyphenylene ether resin and polyamide resin as main components, which are often used in automobile bodies, bumpers, and the like.

Known polyphenylene ethers can be used, such as poly(2,6-dimethyl-1,4-phenylene)
Ether, poly(2,6-ethyl-1,4-phenylene)ether, poly(2-methyl-6-nityl-L4-
phenylene) ether, poly(2-methyl-6-probyl-1,4-phenylene) ether, poly(2,6-diprobyl-1,4-phenylene) ether, poly(2-
Examples include ethyl-6-broby-1,4-phenylene) ether and copolymers of these with styrene. Also, known polyamides can be used, and preferred specific examples include polycapramide (nylon 6), polyhexamethylene adipamide (nylon 6.6), and polyhexamethylene sebacamide (nylon 6.10). ), polyundecaneamide (nylon 11
), polydodecanamide (nylon 12), amorphous nylon, and copolymers of these polyamides.

In the resin composition as the material to be coated, the polyphenylene ether and polyamide are made compatibilized by a compound having a specific functional group such as citric acid, maleic anhydride, or an epoxy compound, as is already known. is preferred.

In addition to polyphenylene ether resin and polyamide resin, this resin composition also contains rubbery polymers, such as
Natural rubber, butadiene polymer, butadiene-styrene copolymer and its hydrogenated products (including all random copolymers, block copolymers, graft copolymers, etc.), isoprene polymer, chlorobutadiene polymer, butadiene −
Acrylonitrile copolymer, isobutylene polymer, isobutylene-isoprene copolymer, acrylic acid ester polymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, thiol rubber copolymer, polysulfide rubber, polyurethane rubber, Polyethylene rubber (for example, polypropylene oxide, etc.), shrimp chlorohydrin rubber, etc.: Styrenic polymers, such as homopolymers of styrene or its derivatives, as well as polybutadiene, polyisoprene, butyl rubber, EDPM, ethylene rubber, etc.
Propylene copolymers, natural rubber, styrenic polymers mixed with or modified with natural or synthetic elastomeric materials such as shrimp chlorohydrin, and also styrene-containing copolymers, such as styrene-acrylonitrile copolymers. (SAN), styrene-maleic anhydride copolymer, and styrene-acrylonitrile-butadiene copolymer (ABS). Preferred styrenic polymers for the present invention may include homopolystyrene, rubber reinforced polystyrene, and the like.

It can also be used as ε, in which conventional additives such as inorganic fillers, flame retardants, stabilizers, etc. are added.

Furthermore, in consideration of physical properties to molded products, adhesion of coating films, improvement of surface appearance of products, etc., polyphenylene ether resin and polyamide resin are used in the resin composition used in the present invention. Preferably, amounts of 0 to 70% and 100 to 30% by weight, respectively, are included.

In the present invention, the resin composition, which is the above-mentioned material, is treated with a surfactant represented by the above-mentioned structural formula, and then painted without applying a primer.

These surfactants are generally water, alcohols (e.g. methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, etc.), or other organic solvents (e.g. Ll, L), 1.1.2 -1- IJ It can be used as a solution dissolved in one or more of chloroethylene, toluene, xylene, methylene chloride, methyl ethyl ketone, etc.). Although the surfactant concentration in the solution is not particularly limited, it is preferable to use the surfactant as an active ingredient in a solution of about 0.1 to 20% by weight.

The above-mentioned surfactant treatment can be carried out by spraying, dipping, or the like.

Furthermore, in the coating method according to the present invention, in order to obtain good adhesion of the coating film, the molded article to be coated is treated with an acid treatment agent containing an inorganic acid, an organic acid, and/or their salts, and then a surfactant is added. Treatment with agents is convenient.

Preferred examples used in the present invention! Examples of acids include hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid. Also,
Examples of organic acids include formic acid, acetic acid, and propionic acid. Among these, phosphoric acid is particularly suitable. These acids can generally be used as an aqueous solution of one or more acids. Furthermore, the above-mentioned acid salts can also be used as the acid treatment agent.

These salts are usually used together with an acid, but can also be used alone if it is acidic. The concentration of acid in the acid treatment aqueous solution to obtain good adhesion and appearance of the coating film varies depending on the type of acid, treatment temperature and treatment time. For example, in the case of phosphoric acid, 80°C
If you decide to process at the above temperature for 60 seconds or more, 0.
It is possible to use a concentration of 0.001% or less, but practically it is
It is preferable to treat at a temperature of room temperature (23°C) to 80°C for 60 to 300 seconds at a concentration of 50%.

In the coating method of the present invention, after the treatment with the surfactant, a top coat is applied, for example, by electrostatic coating, air spray coating, etc., without applying a primer (including a conductive primer). In addition, if necessary,
An intermediate coat can also be applied before the top coat. As the top coat, all paints used as top coats for automobile bodies, such as melamine cross-linked polyester polyol resin paints, melamine cross-linked acrylic resin paints, etc., can be used.

〔Effect of the invention〕

Compared to conventional surfactants, the surfactant used in the coating method of the present invention causes less decrease in surface resistance even when baked after coating, so it can be recoated by electrostatic coating. It also has the effect of reducing paint repellency compared to conventional methods. Therefore, even if there are variations in the amount of surfactant deposited, a good painted appearance can be obtained.

〔Example〕

Examples of the present invention will be disclosed below. GT as a base material
X6006 (trade name, resin composition containing polyphenylene ether resin and polyamide resin, manufactured by Nippon GE Plastics ■) was used.

These base materials were soaked in a 20% by weight phosphoric acid aqueous solution at 60°C for 5 minutes.
After soaking for a minute, rinse with water and place in a hot air dryer at 100°C15.
Dry for a minute. The base materials treated in this way are shown below (I
Surfactant represented by formula X), product name similar to Elique PS92, quaternary ammonium salt type surfactant: Yoshimura Oil Chemical
A solution prepared by diluting 50% of the active ingredient) with isopropyl alcohol to the concentration shown below was used.

Immerse the above-mentioned base material in the above solution and stand it vertically for 75 minutes.
Dry with warm air at ℃. The following tests were conducted on the test piece thus obtained.

(1) Surface resistance The surface resistance of the test piece was measured in accordance with JIS 6911r general test method for thermosetting plastics. Also,
The substrate treated with the surfactant was baked several times in a hot air oven at 160°C for 30 minutes, and after being left at room temperature for 1 hour, the surface resistance was measured after each baking.

(2) Paint adhesion and paint appearance evaluation Amirac white (trademark, manufactured by Kansai Paint ■) was applied as a paint to the test piece using the electrostatic coating method, left for 10 minutes, and then baked in a hot air oven at 140"C for 30 minutes. A coating film with a thickness of 35 μm was obtained.The painted appearance of the obtained coated board was visually evaluated, and the following coating film adhesion test was conducted.

■Initial adhesion test After the base grain test according to JIS K 5400, the tape was peeled off and the number of creases in 100 squares and the number of creases where the coating film remained were counted.

(2) Secondary adhesion test After immersing the test piece in 40°C warm water for 10 days, a test similar to the above initial adhesion test is conducted.

The results of the above evaluations and tests are shown in Table 1. In addition, the painted appearance was evaluated based on the following criteria.

O: Good appearance Δ: Some paint repellency ×: Significant paint repellency [Comparative example] The surfactant is a surfactant represented by the following formula (X), Elique PS 909 (trade name, quaternary ammonium salt) The experiment was carried out in the same manner as in Example 1, except that a surfactant type surfactant (manufactured by Yoshimura Yukagaku ■, active ingredient 50%) was used. The results are shown in Table 2.

Table 2

Claims (1)

[Claims] 1. A method for coating a resin molded article containing polyamide, which contains 30% by weight or more of a composition represented by any of the following structural formulas (I) to (VIII) as an active ingredient. A method for painting a resin molded article, which is characterized in that the resin molded article is treated with a surfactant and then painted without applying a primer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼( IV) [Here, -A-:-CH_2CH_2 or ▲formula,
There are chemical formulas, tables, etc. ▼] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (V) [Here, B: -OH, -NH_2, -NHOCR_0
, -OOCR_0, R_0: Alkyl group of C_1 to C_2_2] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VI) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (VII) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ( VIII) Here, R_1, R_5: C_3_4 and C_5_1
The alkyl groups of dimer acids and trimer acids produced by the polymerization of unsaturated fatty acids, dimer acids include monocyclic forms, which have ▲mathematical formulas, chemical formulas, tables, etc.; Cyclic form, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Bicyclic form, alkyl groups from fatty acids, etc. that have the respective structures, and R_2, R_3, R_6, R_7: C_1 to C_
3 alkyl group and/or -(DO)_nH polyalkylene glycol group (n = 1 to 10), R_4: C_1 to C_2 alkyl group or benzyl group or -(DO)H hydroxyalkyl group or -
CH_2COOC_nH_2_n_+_1 (n=1~3
) acetate group, [D:-CH_2CH_2- or ▲There are mathematical formulas, chemical formulas, tables, etc.▼]X^-: Cl^
-, Br^- and other halogen groups -OSO_3C_nH_2
_n+1 (n=1-2) monoalkyl sulfate group, NO_
3^-, SO_4^-, H_2PO_4^- mineral acids, C
_nH_2_n_+_1COOH (n=1 to 18) or an organic acid having a -COOH group, R_8^-: -CH_2COO^-, -(CH_2)_
nSO_3^-(n=1-3). 2. The method for coating a resin molded article containing polyamide according to claim 1, wherein the surfactant contains a composition represented by structural formulas (I) to (VIII) in an amount of 50% by weight or more as an active ingredient. A method of containing a surfactant. 3. In the method for coating a resin molded article containing polyamide according to claim 1 or 2, before the treatment with the surfactant, treatment with an acid treatment agent containing an inorganic acid, an organic acid and/or a salt thereof. how to.