JPS5952912B2 - Coating resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating resin composition that firmly adheres to metals, ceramics, etc. and has excellent physical properties such as boiling water resistance, hot water resistance, mechanical strength, and corrosion resistance.

Modified ethylene-vinyl acetate copolymers have good adhesion to metals and ceramics, and have excellent mechanical strength and transparency, and are used in many applications such as coating metal and ceramic containers. However, ethylene-vinyl acetate copolymer or modified ethylene-vinyl acetate copolymer
It has the disadvantage that it becomes stratified in boiling water and hot water, and its adhesion to technical garments and mechanical strength are significantly reduced. For these reasons, the present inventors have made extensive studies to improve the above-mentioned drawbacks, and as a result, the above-mentioned drawbacks have been improved by blending a specific amount of a specific compound into a modified ethylene-vinyl acetate copolymer. Boiling water resistance, hot water resistance, stain resistance,
It was discovered that mechanical strength, corrosion resistance, and solvent resistance are significantly improved, leading to the present invention.

That is, the present invention uses a modified ethylene-vinyl acetate copolymer A and a low polymer B of maleic anhydride and styrene as active ingredients, and (A):(B)■100:1-40
(weight ratio).

The modified ethylene-vinyl acetate copolymer A used in the present invention is an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 40 mol%.
J refers to (i) a hydrolyzate of a vinyl acetate copolymer or an ethylene-vinyl acetate-unsaturated carboxylic acid copolymer, or (ii) a graft polymer obtained by further grafting an unsaturated carboxylic acid to the hydrolyzate.

The above-mentioned hydrolyzate is not limited to the hydrolysis rate of the acetoxy group, and includes partially saponified products or completely saponified products, but those with a hydrolysis rate of 50 to 100% are particularly preferred. Here, the unsaturated carboxylic acid is typified by (meth)acrylic acid, and the content of unsaturated carboxylic acids such as (meth)acrylic acid in the ethylene-vinyl acetate-unsaturated carboxylic acid copolymer is usually ethylene-vinyl acetate. 0 for
．． It is 3 to 5% by weight. Moreover, the graft polymer is (
It is obtained by graft polymerizing 0.3 to 5% by weight of an unsaturated carboxylic acid such as meth)acrylic acid to the above hydrolyzate. The low polymer of maleic anhydride and styrene used in the present invention (hereinafter referred to as low polymer □) is an oligomer whose main component is a component with a molecular weight of 1000 or less.
of! 5 means.

In addition, the styrene in the low polymer □ is, for example, a general formula (where B1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and Xl and X2 are independently a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, aralkyl group or halogen atom),
Specifically, styrene, α-methylstyrene, α,2-dimethylstyrene, α,3-dimethylstyrene, α,4-
Dimethylstyrene, α,24,monotrimethylstyrene,
Examples include α-methyl-4-chlorostyrene, and one or more of these may be used.

Furthermore, as maleic anhydride in low polymer 8, a part of the acid anhydride group has the general formula (however, Yl and Y2 represent an alkoxyl group, a hydroxyl group, an amino group, or a halogen atom, etc., but are not limited to S). ) can also be used.

The low polymer 8 contains maleic anhydride and styrene as essential components, but one or more unsaturated monomers such as acrylic acid and acrylic esters may also be used. The role of the low polymer 8 in the present invention is to cause a crosslinking reaction by the reaction between the acid anhydride group and the hydroxyl group in the modified ethylene monovinyl acetate copolymer. For the crosslinking reaction, two or more acid anhydride groups are required in the low polymer 8, but if the number of acid anhydride groups is one or less. There is no problem even if a certain adduct is included as long as it does not impair the characteristics of the present invention. In addition, a catalyst may be added to these resin compositions to promote the crosslinking reaction, and a coating film fluidity regulator may be used to smooth the coating film.

In the coating resin composition of the present invention, the blending ratio of modified ethylene monovinyl acetate copolymer A, maleic anhydride and styrene low polymer B is usually A:B=10 by weight.
0:1-40, more preferably (A):(B)=10
0:3-20.

Here, if component (B) is less than 1% by weight relative to component (4), the effects in boiling water resistance, hot water resistance, corrosion resistance, and solvent resistance will not be sufficient; If it exceeds this, the smoothness and mechanical strength will be poor. The coating resin composition of the present invention contains the above-mentioned components A and B as active ingredients, but pigments and the like can be further blended as necessary for the purpose of use.

The pigments referred to herein are those generally used for paint purposes, and are not limited to organic pigments, inorganic pigments, coloring pigments, extender pigments, etc. The coating resin composition of the present invention is prepared by heating and melt-mixing the above-mentioned components in a conventional manner, for example, using an extruder, hot roll, Banbury mixer, or the like.

The coating resin composition thus obtained can be coated on an adherend by a known method such as a fluidized dipping method, an electrostatic coating method, a hot spraying method, a spray coating method, or a dipping coating method. .

The present invention will be explained below with reference to Examples.

Reference example 1 (Production example of a low polymer of maleic anhydride and styrenes)
588.4 ml of maleic anhydride in a 114 Turow flask equipped with a reflux condenser, dropping spout, thermometer and stirrer.
g (6.0 mol) was charged, and the temperature was raised to melt to 180°C.

Styrene 182 prepared in advance after reaching 180℃
．． 2g (1.75 mol) and dimethylstyrene*23
Pour 31.4 g (1.75 mol) of the mixed solution through the dropping spout.
It dripped in time.

The temperature during dropping was maintained at 180-190°C. After the dropwise addition was completed, the mixture was kept at the same temperature for 2 hours, and the reaction product was taken out. The resulting resin was a light brown solid with a softening point of 115°C. This will be referred to as resin 3. *) Dimethylstyrene is α,
It is a mixture of 4-dimethylstyrene and α,2-dimethylstyrene, with a composition ratio of about 6:4.

Also, instead of styrene and dimedylstyrene in the above example, 413.7g of α-methylstyrene (3.
The same operation as in the above example was performed except that 5 mol) was used to obtain a light brown solid with a softening point of 110°C.

This will be referred to as resin 5. Example 1 Melt index 150, vinyl acetate content 11.2
Resin 8 synthesized in Reference column 1 was added to a modified Gojin monovinyl acetate copolymer with a hydrolysis rate of 98% obtained by hydrolyzing ethylene monovinyl acetate copolymer of mol % to a weight ratio of 92:
8 and kneaded for 10 minutes on a test roll heated to 120 to 130°C to form pellets. After pulverizing the pellets using a pulverizer (manufactured by Alpine, 11,000 rpm), the pellets were passed through a vibrating sieve. The powder was sieved to obtain 200 mesh powder.

This powder was applied at a voltage of 70 KV and a powder ejection amount of 100 g/1.
After electrostatic coating for 0 minutes, it was baked for 10 minutes in a hot air drying oven at 180°C. Various tests were conducted on the resulting coating film, and the results shown in Table 1 were obtained. Example 2 The same modified ethylene monovinyl acetate copolymer used in Example 1, Resin 8 and titanium oxide (Tiepeke R-82
0 Ishihara Sangyo Co., Ltd. product) at a weight ratio of 82.8:7.2:10.
A resin composition was powdered in the same manner as in Example 1 except that a mixture of 0.0 and 0.0% was used, and electrostatic coating and coating film baking were performed in the same manner.

Table 1 shows the performance of the resulting coating film. Example 3 Electrostatic coating and baking of the coating film were carried out in exactly the same manner as in Example 1 except that Resin 5 was used instead of Resin 3 in Example 1.

Table 1 shows the performance of the resulting coating film. Example 4 Electrostatic coating and baking of the coating film were carried out in exactly the same manner as in Example 2, except that Resin 5 was used instead of Resin 3 in Example 2.

Table 1 shows the performance of the resulting coating film. Example 5 In place of the modified ethylene monovinyl acetate copolymer in Example 1, ethylene monovinyl acetate-acrylic acid copolymer (melt index 140, vinyl acetate content 12 mol%, acrylic acid content 2 mol) was used. Electrostatic coating and baking of the coating film were carried out in exactly the same manner as in Example 1, except that a modified ethylene monovinyl acetate copolymer with a hydrolysis rate of 98% obtained by hydrolyzing %) was used.

Table 1 shows the performance of the resulting coating film. Comparative Example 1 Only the same modified ethylene monovinyl acetate copolymer used in Example 1 was sieved using a vibrating sieve to form a powder of 200 mesh, which was then electrostatically coated and baked in the same manner as in Example 1. Summer.

Table 1 shows the performance of the resulting coating film. Comparative Example 2 The same modified ethylene monovinyl acetate copolymer used in Example 1 was mixed with titanium oxide (Tiepeque R-820) at a weight ratio of 9:1, pulverized, and then sieved to 200 mesh pieces. powder was obtained.

The obtained powder was electrostatically coated in the same manner as in Example 1 and baked to obtain a coating film. Table 1 shows the performance of the resulting coating film. (Support) Test conditions 1) Film thickness: 50 to 60μ 2) Adhesion: Vertical test 3) Eric's ν value: JISZ-2247 4) Boiling water resistance: Immersed in boiling water for 1 hour

Claims (1)

[Claims] 1 Modified ethylene-vinyl acetate copolymer A and maleic anhydride and styrene low polymer B are used as active ingredients,
A coating resin composition characterized in that A:B=100:1 to 40 (weight ratio).