JPH10168379A - Polyethylene-based powder coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating material composition improved in adhesiveness and gloss and excellent in weather resistance in the case exposed under outdoor severe conditions by compounding polyethylene resin with a specific copolymer resin and a nucleating agent. SOLUTION: This coating material composition is obtained by compounding (A) 100 pts.wt. polyethylene resin (preferably having 1-100g/10min melt flow rate) with (B) 1-100 pts.wt. ethylene-acrylic acid copolymer resin (preferably having 1-20wt.% acrylic aid content) and (C) 0.05-3 pts.wt. nucleating agent. Sugar alcohol such as D-sorbitol or condensate of a sugar alcohol such as dibenzilidene sorbitol with benzaldehyde is preferably used as the component C. The composition is preferably obtained by mixing, e.g. the components A to C by Henschel mixer, etc., melting the mixture by an extruder, etc., molding the mixture into pellets and pulverizing the pellets. Furthermore, particle diameter of the composition is preferably 50-400μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a powder coating composition. More specifically, the present invention relates to a polyethylene-based powder coating composition that gives a coating film having excellent adhesion, gloss, and weather resistance when powder coating is performed.

[0002]

2. Description of the Related Art Conventionally, there has been known a method in which a metal material is coated with a powder paint to impart aesthetics, rust prevention, weather resistance, chemical resistance and the like to the material. As the powder coating in this case, those having a thermoplastic resin as a component and those having a thermosetting resin as a component have been commercialized in various ways.

[0003] However, powder coatings containing a non-polar thermoplastic resin such as polyethylene as a component generally have extremely poor adhesion to the metal of the obtained coating film, and also have problems in terms of gloss and weather resistance of the coating film. There's a problem. Therefore, it has been practiced to improve the adhesiveness to metal by mixing polyethylene with a polyolefin modified with an unsaturated carboxylic acid or an anhydride thereof (Japanese Unexamined Patent Publication No. Hei.
259937, JP-B-3-46028).
Attempts have also been made to improve weather resistance by adding various weather stabilizers. However, the method of mixing the polyolefin has a drawback that when the coated product is used outdoors, swelling occurs, or when the coating is damaged by impact or the like, the coating is peeled off. The one to which the weather stabilizer is added has a disadvantage that the weather resistance is not sufficient when used outdoors for a long period of time.

[0004]

DISCLOSURE OF THE INVENTION The present invention improves the adhesiveness and gloss, which are the drawbacks of polyethylene-based powder coatings, as well as the weather resistance when exposed to severe outdoor conditions, and particularly damages to the coating film. It is an object of the present invention to provide a polyethylene-based powder coating composition having excellent weather resistance in a state in which cracks occur.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result,
The present inventors have found that a coating film having excellent adhesiveness and gloss and excellent weather resistance can be obtained by blending the ethylene-acrylic acid copolymer resin and the nucleating agent, and the present invention has been achieved.

That is, the gist of the present invention is as follows: (1) 1 to 100 parts by weight of an ethylene-acrylic acid copolymer resin and 0.05 to 3.0 parts of a nucleating agent for 100 parts by weight of a polyethylene resin.
And (2) a polyethylene resin having a melt flow rate of 1
The powder coating composition according to the above (1), which is a resin of from 100 to 10 g / 10 minutes; and (3) the ethylene-acrylic acid copolymer resin, wherein the acrylic acid content of the resin is 1 to 20% by weight. (4) The powder coating composition according to any one of the above (1) to (3), wherein the nucleating agent is a sugar alcohol or a condensate of a sugar alcohol and benzaldehyde.

[0007] The nucleating agent used in the present invention is usually used to enhance the gloss and transparency of the coating film. However, the addition of the nucleating agent makes it possible to obtain a polyethylene powder coating composition having excellent weather resistance. This is a surprising and remarkable effect.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyethylene resin used in the present invention has a melt flow rate of 1 to 100 g / 1.
A range of 0 minutes is preferable, and the range is not particularly limited as long as it is within the range. When a polyethylene resin having a melt flow rate of less than 1 g / 10 minutes is used, the meltability is poor, and the surface of the coating film is not smooth. The so-called edge break, which causes insufficient coverage of the edge of the object,
Not preferred.

The ethylene-acrylic acid copolymer resin used in the present invention has an acrylic acid content of 1-2.
The amount is preferably 0% by weight, and is not particularly limited as long as it is within the above range. When the ethylene-acrylic acid copolymer resin having an acrylic acid content of less than 1% by weight is used, the adhesiveness is poor. When the acrylic acid content is more than 20% by weight, the adhesiveness is obtained but the pulverizability becomes extremely poor. When used as a body paint, there is a problem that powder blocking occurs.

The amount of the ethylene-acrylic acid copolymer resin is usually 1 to 100 parts by weight of the polyethylene resin.
100 parts by weight, preferably 10 to 80 parts by weight. 1
If the amount is less than 100 parts by weight, the adhesiveness is poor. If the amount exceeds 100 parts by weight, the pulverizability becomes poor, and it is difficult to obtain a powder suitable for powder coating.

In the present invention, in addition to the above-mentioned resins, a nucleating agent which has been conventionally added for improving the gloss and transparency of the coating film is blended, so that the weather resistance is remarkably improved in addition to the above-mentioned effects. It is found that it is done.

The nucleating agent used in the present invention is preferably an organic substance, for example, an organic acid such as stearic acid, arachiic acid, benzoic acid or terephthalic acid; a saturated fatty acid amide such as stearic acid amide or arachidic acid amide; Sugar alcohols such as D-sorbitol, tetrit, penchit, and hexit; condensates of sugar alcohols and aldehydes and the like are usually used. Among them, sugar alcohols and condensates of sugar alcohols and benzaldehyde are preferably used. Specific examples thereof include D-sorbitol as a sugar alcohol, and dibenzylidene sorbitol or dibenzylidene sorbitol substituted with an alkyl group having 1 to 4 carbon atoms as a condensate of a sugar alcohol and benzaldehyde.
For example, bis (p-methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol, bis (p-propylbenzylidene) sorbitol, bis (p-butylbenzylidene) sorbitol and the like can be mentioned.

The amount of the nucleating agent is usually 0.05 to 3.0 parts by weight, preferably 0.1 to 2.0 parts by weight, based on 100 parts by weight of the polyethylene resin. If the amount is less than 0.05 part by weight, gloss and weather resistance are poor. If the amount is more than 3.0 parts by weight, whitening due to bleeding of the nucleating agent exposed on the surface of the coating film appears, and not only has no commercial value, but also the adhesive strength is reduced. And is not preferred.

The polyethylene-based powder coating composition of the present invention is prepared by mixing the above-mentioned polyethylene resin, ethylene-acrylic acid copolymer resin and nucleating agent in a desired ratio using a super mixer, a Henschel mixer or the like, and then extruding the mixture. Machine,
After being melted and homogenized with a Banbury mixer, kneader or the like, it is formed into, for example, pellets, which are further subjected to 40 to 50.
It is obtained by pulverizing to a particle size in the range of 0 micron, preferably 50 to 400 micron. Alternatively, the polyethylene resin, which has been finely pulverized in the above-mentioned particle size range, the ethylene-acrylic acid copolymer resin and the nucleating agent may be uniformly mixed at a predetermined ratio.

The powder coating composition thus obtained may be further blended with usual additives such as heat stabilizers, weather stabilizers, powder flow improvers, antistatic agents and pigments.

The polyethylene powder coating composition of the present invention is applied to a substrate by a conventional powder coating method, for example, a fluid immersion method, an electrostatic coating method, a thermal spraying method or the like. The substrate is not particularly limited, but metals, mainly iron, iron alloys, zinc, or plated products thereof are preferably used.

[0017]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

Examples 1 to 3 Linear low-density polyethylene having a melt flow rate of 10 g / 10 min (Ultzex 2510 manufactured by Mitsui Petrochemical Co., Ltd.)
0), an ethylene-acrylic acid copolymer resin (manufactured by Mitsubishi Chemical: Yucalon A220S, acrylic acid content: 7% by weight) and dibenzylidene sorbitol (manufactured by Marubishi Yuka: Denone YK2) as a nucleating agent, as shown in Table 1. Premixed in a Henschel mixer, and then melt mixed in an extruder to obtain pellets. The pellets are mechanically pulverized to a particle size of 50-2.
The powder was classified to 70 μm to obtain a powder coating composition.

Examples 4 and 5 Low-density polyethylene having a melt flow rate of 20 g / 10 min (Sumikasen G801 manufactured by Sumitomo Chemical Co., Ltd.)
Except that acrylic acid copolymer resin (Exxon Chemical: Escol 5110, acrylic acid content 13% by weight) and dibenzylidene sorbitol (Nippon Rika: Gelol D) as nucleating agents were used in the amounts shown in Table 1. A powder coating composition was obtained in the same manner as in Example 1.

Comparative Example 1 A powder coating composition was obtained in the same manner as in Example 1 except that no nucleating agent was added.

Comparative Example 2 A powder coating composition was obtained in the same manner as in Example 1 except that no ethylene-acrylic acid copolymer resin was added.

Comparative Example 3 Linear low-density polyethylene having a melt flow rate of 10 g / 10 min (Ultzex 2510 manufactured by Mitsui Petrochemical Co., Ltd.)
A powder coating composition was obtained in the same manner as in Example 1 except that only 0) was used.

Using the powder coating compositions obtained in Examples 1 to 5 and Comparative Examples 1 to 3, a test piece was coated by a fluid immersion method. That is, 70 × 150 × 2
(Mm) test piece (material: iron or galvanized)
Was heated in a heating furnace at about 360 ° C. for 6 minutes, and then immersed in a fluidized immersion tank for 6 seconds. Return to heating furnace again, about 200 ℃
For 2 minutes and cooled to room temperature to obtain a powder-coated product.
About the obtained powder coating product, a coating film (film thickness: 500-6)
(00 μm). Table 1 shows the results. The evaluation method and criteria are as follows.

(Gloss) The surface of the coated product was visually observed. ◎: glossy ○: slightly glossy ×: no gloss

(Adhesive force) A parallel notch having a width of 25 mm is inserted into the painted product with a cutter knife so as to reach the metal material.
The film was peeled in a direction of 180 degrees by a tensile tester, and the adhesive strength was measured (unit: kg / 25 mm width).

(Weather resistance) A cross-notch was inserted into the painted product and the painted product by a cutter knife so as to reach the metal material, and an exposure test was performed for 2,000 hours using a sunshine weather meter (manufactured by Suga Test Machine). The surface condition and the state of peeling of the coating film from the notch were observed. ：: No cracks or swelling on the surface of the coated product, and no peeling from the notch portion was observed for the coated product with a notch, and the weather resistance was good. △: The coating product was swelled and a notch was formed on the surface. Painted products peeled off from the notch part and the weather resistance was slightly poor. ×: Cracks and blisters were observed on the surface of the coated product, and peeled off notch parts were observed for the coated products with notches. Poor sex

[0027]

[Table 1]

As is clear from Table 1, when the powder coating compositions of the present invention were used, coating films having gloss, good adhesion and excellent weather resistance were obtained. On the other hand, in Comparative Example 1 in which no nucleating agent was added, there was no gloss and no weather resistance was observed. In Comparative Example 2 in which the ethylene-acrylic acid copolymer resin was not added, the adhesiveness was poor,
Therefore, no weather resistance was observed. In Comparative Example 3 in which neither the ethylene-acrylic acid copolymer resin nor the nucleating agent was added, none of gloss, adhesion, and weather resistance was observed.

[0029]

The polyethylene powder coating composition of the present invention has excellent adhesiveness and gloss and excellent weather resistance by blending an ethylene-acrylic acid copolymer resin and a nucleating agent with a polyethylene resin. Can be formed. In particular, it is useful because it has excellent weather resistance even when the coating film is damaged.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Goto 1384-1 Uetakano, Yachiyo-shi, Chiba Sumitomo Seika Co., Ltd.

Claims (4)

[Claims] [Claim 1] For 100 parts by weight of a polyethylene resin,
A polyethylene powder coating composition comprising 1 to 100 parts by weight of an ethylene-acrylic acid copolymer resin and 0.05 to 3.0 parts by weight of a nucleating agent. 2. The powder coating composition according to claim 1, wherein the polyethylene resin is a resin having a melt flow rate of 1 to 100 g / 10 minutes. 3. An ethylene-acrylic acid copolymer resin having an acrylic acid content of 1 to 20% by weight.
A powder coating composition as described in the above. 4. The powder coating composition according to claim 1, wherein the nucleating agent is a sugar alcohol or a condensate of a sugar alcohol and benzaldehyde.