JPH01165675A - Powder coating material composition - Google Patents

Abstract

PURPOSE:To realize the formation of a powder coating material composition which has improved fluidity, friction melting resistance, etc., and gives a good coated surface, by incorporating a solid polyolefin into a thermosetting powder coating material composition. CONSTITUTION:This thermosetting powder coating material composition for electrostatic coating comprises a solid polyolefin of a number-average molecular weight of 20,000 or lower in an amount of 0.1-5 pts.wt. based on 100 pts.wt. total of resin and curing agent for the resin. Examples of the polyolefin include polyethylene, polypropylene, an ethylene/propylene copolymer, and mixtures thereof.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a thermosetting powder coating composition for electrostatic coating that has improved fluidity, friction melting properties, etc., and has excellent coating workability. It is about things.

[Conventional technology and its problems]

Electrostatic spray coating is widely used as a powder coating method due to its high coating efficiency.

By the way, in electrostatic spray painting, air is used to transport the powder paint from the paint tank to the spray gun, but the pressure is quite high, and as a result, the powder paint during transport is Part of the powder coating may melt due to collision or friction inside the device, and the powder may fuse together, or
Furthermore, there was a problem in that powder paint was fused as cholesterol to a part of the ejector of the paint tank and inside the paint hose.

As a result, the resulting coating film becomes poor, and if powder coating is continuously transported, it gradually becomes unstable.
Therefore, it is necessary to frequently clean the conveying device, which requires a large number of man-hours, and the painting workability is poor.

This tendency is particularly likely to occur in thermosetting powder coatings that use low molecular weight resins, compared to thermoplastic powder coatings.

In view of the current situation, as a result of intensive research, the present invention has discovered a thermosetting powder coating composition for electrostatic coating that solves the above problems and has excellent fluidity, friction melting resistance, etc. This has led to the present invention.

[Means to resolve the problem]

That is, in the thermosetting powder coating composition for electrostatic coating, the present invention contains 0 solid polyolefin having a number average molecular weight of 20.000 or less per 100 parts by weight of the resin and curing agent.
．． The present invention relates to a powder coating composition characterized in that it contains 1 to 5 parts by weight.

By melt-mixing a solid polyolefin into a thermosetting powder coating, the present invention unexpectedly has good fluidity during transportation to a spray gun, and also prevents particles from colliding with each other or by friction inside the device. The inventors have discovered that as a result, it becomes difficult for the powder to fuse together, or for the powder paint to fuse to a part of the ejector of the paint tank or inside the paint hose.

The mechanism by which these effects occur is not clear, but it is thought that the polyolefin partially protrudes near the powder surface, which improves slippage, resulting in better fluidity and less frictional resistance. .

The present invention will be explained in detail below.

The thermosetting powder coating used in the present invention is composed of conventionally known resins, curing agents, and, if necessary, various pigments, additives, etc., such as polyester resins, epoxy resins, etc. A typical example is an acrylic resin thermosetting powder coating. The method for producing it is to melt and knead the mixture of the components using an extruder, hot roll, kneader, etc. at a temperature that does not cause a crosslinking reaction between the resin and the curing agent, and then to crush the mixture after cooling. are mentioned as typical examples, but it goes without saying that the invention is not limited to these, and that other conventionally known manufacturing methods can also be employed.

Typical resins that are constituent components of thermosetting powder coatings include polyester resins, epoxy resins, acrylic resins, and the like. Polyester resins include carboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and β-oxypropionic acid, as well as ethylene glycol, propanediol, butanediol, bentanediol, hexanediol, neo Typically used are those obtained by reacting polyhydric alcohols such as pentyl glycol, trimethylolprohane, and pentaerythritol in a conventional manner.

Epoxy resins are compounds with two or more epoxy groups in the molecule, including glycidyl ether type resins such as the condensate of bisphenol A and epichlorohydrin, glycidyl ester type resins, glycidyl amine type resins, alicyclic epoxy resins, Linear aliphatic epoxy resins are typically used.

Examples of the acrylic resin include monomers such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and styrene; glycidyl acrylate; Typically used are glycidyl group-containing monomers such as glycidyl methacrylate and 2-methylglycidyl methacrylate, which are polymerized by a conventional method.

The curing agent, which is a component of the thermosetting powder coating, is appropriately selected depending on the type of resin, but for example, 2 equivalents or more per molecule of blocked polyisocyanate, adipic acid, succinic acid, sebacic acid, etc. Compounds containing carboxyl groups or acid anhydrides, aminoplast resins, epoxy resins, etc. are typically used.

Pigments include coloring pigments such as titanium dioxide, red iron oxide, iron oxide, carbon black, phthalocyanine blue, phthalocyanine green, quinacridone pigments, azo pigments, and isoindolinone pigments, silica, talc, precipitated barium sulfate, and calcium carbonate. Extender pigments such as are typically used.

As additives, anti-sag agents, surface conditioners, crosslinking promoting catalysts, etc. are used.

The thermosetting powder coating of the present invention is produced by blending a solid polyolefin into a composition made of these components during the melt kneading process.

Typical polyolefins used in the present invention include polyethylene, polypropylene, ethylene-propylene copolymers, and mixtures thereof.

The polyolefin that can be used is a polyolefin that is solid at room temperature and has a number average molecular weight of 20,000 or less, particularly preferably 000 or less. If the molecular weight of the polyolefin is too large than the above range, the compatibility with other resins will be poor, the resulting coated surface will tend to have a citron skin, and the effect of friction melting resistance will be reduced, which is not preferable.

The appropriate amount of polyolefin to be blended is 1 to 5 parts by weight, particularly preferably 0.3 to 3.5 parts by weight, based on 100 parts by weight of the resin serving as the binder and its curing agent. If the blending amount is less than the above range, the effects of the present invention cannot be obtained, and if it is too large, the coating surface condition will be adversely affected, which is not preferable.

〔Effect of the invention〕

According to the present invention, by blending a solid polyolefin into a thermosetting powder coating, the fluidity, friction melting properties, etc. of the powder coating are improved, and the electrostatic coating has good workability and a good coated surface condition. A powder coating is obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

Note 1) FINDIC M8000J (trade name manufactured by Dainippon Ink and Chemicals) Note 2) rB-1530J (trade name manufactured by Hinils) Note 3) Epicron 4050J (trade name manufactured by Dainippon Ink and Chemical) Note 4 ) A mixture consisting of a surface conditioner and a curing accelerator (7:2) Note 5) Sunwax 161-PJ (trade name: Mn5000, manufactured by Sanyo Chemical Industries, Ltd.) After mixing the above components for about 1 minute in a Henschel mixer. , melt-kneaded in an extruder (Busco Kneader PR46) under a temperature condition of 100 to 120°C, and after cooling, 0.2% of silica fine powder was added to the mixed components, and the mixture was ground in a pantum mill, and then mixed into a 200-mesh wire mesh. and sieved to prepare a powder coating.

Titanium dioxide 25.7 parts Fudakuchi cyanine 10. 3 copies Note 6) rER-6610J (Product name manufactured by Nippon Ester Co., Ltd.) Note 7) “Fleran Ui” (Product name manufactured by Bayer) Note 8) “Epicron 2050J (Product name manufactured by Dainippon Ink & Chemicals Co., Ltd.) Note 9) "Viscol 660-PJ (trade name, manufactured by Sanyo Chemical Industries, Ltd.; Mn3000) A powder coating was prepared from the above components in the same manner as in Example 1.

Precipitated barium sulfate 14.7 parts Titanium dioxide 29.4 parts Yellow iron oxide
1.0 part Red Garla
0.3 R Note 10) “Ester Resin ER-81
01J (S, product name manufactured by Hon-Ester Co., Ltd.) Attention) r Epo) -) YD-014J (product name manufactured by Tobu Kasei Co., Ltd.) Note 12) “Sun7tux LEL-400PJ (product name manufactured by Sanyo Chemical Industries, Ltd.; Mn4000) A powder coating was prepared from the above components in the same manner as in Example 1.

Note 13) "Ester Resin ER-82oo" (trade name manufactured by Nippon Ester Co., Ltd.) Note 14) "Epicor) 828 (trade name manufactured by Yuka Shell Co., Ltd.) A powder coating was prepared from the above components in the same manner as in Example 1. .

Example 5 A powder coating material was prepared in the same manner as in Example 4 except that the amount of solid polyethylene was changed to 4 parts.

Titanium dioxide 54.9 parts Note 15)
"FINDIC A-223SJ (trade name, manufactured by Dainippon Ink & Chemicals) A powder coating was prepared from the above components in the same manner as in Example 1.

Comparative Example 1 A powder coating was prepared in the same manner as in Example 4 except that solid polyethylene was not blended.

Comparative Example 2 A powder coating was prepared in the same manner as in Example 4 except that the amount of solid polyethylene was changed to 8 parts.

Comparative Example 3 Mn3000 was used as solid polyethylene in Example 4.
A powder coating was prepared in the same manner except that 0 high molecular weight polyethylene was used.

Comparative Example 4 A powder coating was prepared in the same manner as in Example 6 except that solid polyethylene was not blended.

The powder coatings produced in each example and comparative example were coated on a polished mild steel plate with a thickness of 0.8 mm using an electrostatic powder coating gun (Model 721 manufactured by Gema Co., Ltd.) at a voltage of -60 KV to a film thickness of 60 μm. Paint it like this,
Baked in a hot air drying oven.

Various tests were conducted on the resulting coating film, and the results are shown in Table 1.

Note 16) Visual judgment ◎: Good, ○: Very slight yuzu skin, △: Yuzu skin, X: Severe yuzu skin Note 17) 6 according to JIS-K-54006, 7
Measure the 0° reflectance Note 18) JIS-Z-22471: Judgment 19) Measure with each inch diameter and 500 g weight according to JIS-K-54006, 13, 3 Note 20) Powder paint , 45 minutes inside the powder coating hose and fluid tank! ffl, and measure the amount of powder coating fused to a part of the ejector (however, the injector air pressure is 5,0 kg/cut; the fluidizing air pressure is 0.2
kg/cut) As is clear from Table 1, the powder coating of the present invention was able to significantly improve frictional adhesion without deteriorating coating performance, and was excellent in coating workability.

On the other hand, Comparative Examples 1 and 4, in which no solid polyolefin was blended, had a high frictional fusion property, and Comparative Example 2, in which an excessive amount of solid polyolefin was blended, had improved friction fusion properties, but the smoothness, gloss, and Coating film properties such as impact resistance deteriorated, and in Comparative Example 3, in which a solid polyolefin with a high molecular weight was used, frictional adhesion was not improved as much.
It resulted in a terrible yuzu skin coating.

Claims (2)

[Claims] (1) In a thermosetting powder coating composition for electrostatic coating, the number average molecular weight is 2 for 100 parts by weight of the resin and its curing agent.
A powder coating composition containing 0.1 to 5 parts by weight of a solid polyolefin having a molecular weight of 0,000 or less. (2) The powder coating composition according to claim (1), wherein the polyolefin is polyethylene, polypropylene, or a mixture thereof.