JPH061867A - Method for coating olefin resin molding - Google Patents

Abstract

PURPOSE:To form a topcoating film excellent in adhesion without using an org. halogenous solvent and without priming by treating the surface of a molding of an acid-modified polyolefin resin with a functional aziridine and applying a topcoating compsn. to the surface directly. CONSTITUTION:The surface of a molding of an olefin resin grafted with 0.1-10wt.% alpha,beta-unsatd. carboxylic acid, unsatd. dicarboxylic acid, or anhydride thereof is treated with a functional aziridine of the formula wherein R1 is H or 1-10C alkyl; and R2 is 1-10C alkyl optionally substd. by one or two aziridine, melamine, or -P=O groups and then directly coated with a topcoating compsn.

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 an olefin resin molded product. More specifically, the present invention relates to a coating method in which the surface energy of an olefin resin molded article is increased by a specific treatment, and then excellent coating adhesion is obtained even when directly overcoating.

[0002]

2. Description of the Related Art Olefin resins have excellent chemical properties,
It is widely used for industrial parts because of its physical properties and electrical properties, but it is chemically inactive because it has no polar group in its molecule, and its paintability is extremely low. For this reason, a method has been used in which various surface treatments are performed on the surface of an olefin resin molded product, and then coating is performed. The surface treatment method is (1) chemical oxidation method (for example, Japanese Patent Publication 3-
503655), (2) radiation graft polymerization method (for example, JP-A-61-233024), (3) UV pre-irradiation method,
(4) Plasma treatment method (for example, JP-A-59-9814)
No. 0, 61-228029) and the like, a method of treating and modifying the surface is proposed. Further, as a general coating method, a method of treating with a halogen-containing organic solvent, followed by primer coating and then top coating is proposed (for example, JP-A-63-172758).

[0003]

However, the chemical oxidation method is a method of oxidizing the surface of a molded article with chromic acid or the like and treating the surface with a functional aziridine or the like, but it requires a waste liquid treatment of the chemical to be used. There is a problem that A radiation graft polymerization method including a method of coating a hydrophilic monomer such as acrylic acid or an acrylic acid ester on the surface of a molded article and then grafting it using γ rays has a slow processing speed and has a problem in economy. The ultraviolet pre-irradiation method not only causes deterioration of the olefin resin, but also has a drawback that the modified surface becomes ineffective as time passes. In addition to the problem that it is difficult to obtain a stable quality plasma processing method, there is a problem in economical efficiency because an expensive apparatus is used. Further, the method of applying a primer after treatment with a halogen-based organic solvent has a problem of environmental pollution of the halogen-based organic solvent and an increase in the number of steps.

[0004]

SUMMARY OF THE INVENTION The present inventors have completed the present invention as a result of intensive studies on a coating method including a surface modification method of an olefin resin in order to solve the above problems. That is, the present invention relates to an α, β-unsaturated carboxylic acid,
Unsaturated dicarboxylic acid or its acid anhydride is 0.1 to 10
This is a method for coating an olefin resin molded product, characterized in that the surface of a molded product of an olefinic resin grafted by weight% is treated with a functional aziridine and then directly overcoated. The present invention will be specifically described below.

(A) An olefin resin grafted with an α, β-unsaturated carboxylic acid, an unsaturated dicarboxylic acid or an acid anhydride thereof (hereinafter referred to as a modified polyolefin). The modified polyolefin used in the present invention is an α, β-unsaturated carboxylic acid, an unsaturated dicarboxylic acid or an acid anhydride thereof having an acid density of 0.
1 to 10% by weight is grafted. If the graft amount is less than 0.1% by weight, the effect of surface modification after the treatment with the functional aziridine will be small and the adhesion of the coating material to be applied thereafter will be reduced. On the other hand, if it exceeds 10% by weight, the mechanical properties of the modified polyolefin molding will be significantly deteriorated.

Examples of the olefin resin as the main chain of the modified polyolefin include stereoregular polypropylene, atactic polypropylene, high density polyethylene, low density polyethylene, propylene / ethylene block copolymer, propylene / ethylene random copolymer, polypropylene. And polyethylene blends, propylene and α-
Examples thereof include olefin copolymers. Examples of the α, β-unsaturated carboxylic acid, unsaturated dicarboxylic acid or acid anhydride thereof include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, maleic anhydride and itaconic anhydride. To be The addition amount of these is not particularly limited, but is usually 0.5 to 15 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the olefin resin.

In the present invention, an organic peroxide is used to accelerate the graft reaction. Examples of the organic peroxide include benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, dicumyl peroxide, α-α′-bis (t-butylperoxydiisopropyl) benzene, 2,5-dimethyl- Two
5-di (t-butylperoxy) hexane, cumene hydroperoxide, t-butyl hydroperoxide and the like can be mentioned. The amount of the organic peroxide added is not particularly limited, but is usually 0.005 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the olefin resin.

The modified polyolefin can be obtained by melt-kneading the olefin resin and these acids or their anhydrides and organic peroxides using a kneader such as a Banbury mixer, a kneader, a roll mill and a screw type extruder.

The (B) functional aziridine is represented by the formula (1). Wherein R ₁ is hydrogen or an alkyl group having 1 to 10 carbon atoms, and R ₂ is an alkyl group having 1 to 10 carbon atoms or 1 or 2 additional aziridine groups, melamine groups, Or 1 substituted by a -P = O group
It is an alkyl group having 10 to 10 carbon atoms.

[Chemical 1]

(C) Surface modification treatment method The surface modification treatment of the molded article (A) with the functional aziridine (B) is carried out by mixing (B) in an organic solvent having no active hydrogen group such as ketone and ether. Immersing the molded body in the solution or directly (B) without using a solvent
Soak in. Processing time is generally short, from 30 seconds
It is 30 minutes, preferably 30 seconds to 5 minutes. Processing temperature is 2
The temperature is 0 ° C to 90 ° C, preferably 20 ° C to 50 ° C.

(D) As the paint used in the present invention, urethane-based, acrylic-based, epoxy-based, melamine-based, etc. paints are used, and urethane-based paints are preferably used.
The present invention is a method in which, after the molded product is treated with aziridine as described above, these paints are directly overcoated on the molded product without using a halogen-containing organic solvent or a primer.

[0012]

The reaction between the compounds (A) and (B) takes place through ring opening of the heterocycle. An example of such a reaction is as follows.

[Chemical 2] In reaction 1

[Chemical 3] And / or —CH ₂ OOC— is considered to be a functional group that enhances the hydrophilicity of the surface, and it is considered that this improves the paintability and adhesiveness.

[0013]

The present invention will be described in more detail with reference to the following examples. In addition, the measuring method of the physical-property value in an Example is shown below. (1) Content of maleic anhydride The content of maleic anhydride in the modified polyolefin was purified by dissolving 1.0 g of the sample in 100 ml of heated xylene and then reprecipitating in 3 liters of methanol, and then in a vacuum dryer. It is dried at 70 ° C for 24 hours, and the transmission IR of the pressed film product is measured to be 1730 cm.
^It was determined from the absorbance of the carbonyl group of ^-1 . (2) Adhesion strength of coating film A coating product is applied to a surface-modified molded product with a spray gun.
The 180 ° peeling strength was measured under the condition of m / min.

Example 1 An injection-molded product (1) of a propylene homopolymer grafted with maleic anhydride at 0.9% by weight.
20 × 120 mm, 2 mmt) with acetone 1: 1
It was immersed for 50 seconds at a temperature of 25 ° C with a trifunctional aziridine (manufactured by Nippon Shokubai Co., Ltd., trade name PZ-33) diluted to a volume ratio of. Then, it was washed with acetone for 1 minute. Then, the molded product was dried by air drying. A two-component urethane paint (Nippon Bee Chemical Co., Ltd., trade name R271 Pure White) was applied to the obtained molded product so as to have a film thickness in the range of 50 to 60 μm, and allowed to stand for 10 minutes at room temperature and then left for 8 minutes.
It was baked and cured in an oven at 0 ° C. for 45 minutes. The results are shown in Table 1.

Example 2 The same method as in Example 1 was used except that the propylene homopolymer grafted with 2.4% by weight of maleic anhydride was used in Example 1.

Example 3 The same method as in Example 1 was used except that the propylene homopolymer used in Example 1 was an ethylene-propylene block copolymer having an ethylene content of 8.7% by weight.

(Embodiment 4) A two-pack type urethane paint was used as a one-pack type polyester / melamine paint in Example 1 (manufactured by Kansai Paint Co., Ltd. under the trade name Soflex NO.121).
1) and the same method as in Example 1 except that the bake hardening temperature was 120 ° C.

(Embodiment 5) The paint used in Embodiment 1 is a one-pack type acrylic paint (manufactured by NOF CORPORATION, Primac No. 3).
001) and the bake hardening temperature was 100 ° C.

Comparative Example 1 The same method as in Example 1 was used except that the propylene homopolymer grafted with maleic anhydride was changed to the propylene homopolymer in Example 1.

Comparative Example 2 Same as Example 1 except that the propylene homopolymer grafted with 0.9% by weight of maleic anhydride in Example 1 was replaced with a propylene homopolymer grafted with 0.02% by weight of maleic anhydride. It was a method.

Comparative Example 3 The same method as in Example 1 was carried out except that the trifunctional aziridine treatment was not carried out.

[0022]

[Table 1]

[0023]

INDUSTRIAL APPLICABILITY The method of the present invention has an effect that the surface of an olefin resin can be modified more simply and cheaply as compared with the conventional technique, and the coating film adhesion with various paints can be improved. . Moreover, since neither halogen-containing organic solvent nor primer is used, there is no problem of environmental pollution.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Aoki 3-2 Chidoricho, Kawasaki-ku, Kawasaki-shi, Kanagawa Akira Kawasaki Plastics Research Laboratory

Claims (1)

[Claims] 1. A surface of a molded product of an olefin resin grafted with 0.1 to 10% by weight of an α, β-unsaturated carboxylic acid, an unsaturated dicarboxylic acid or an acid anhydride thereof is treated with a functional aziridine, and thereafter. A method for coating an olefin-based resin molded article, which is characterized by direct top-coating.