JPS5825116B2 - Fun Taiyoyouji Yushisoseibutsu - Google Patents

Description

Detailed Description of the Invention The present invention comprises a (β-methyl)glycidyl group-containing acrylic polymer, a saturated aliphatic dicarboxylic acid, and (anhydrous) trimellitic acid, and has excellent surface hardness, stain resistance, physical performance, etc. The present invention relates to a resin composition for powder coating that forms an excellent coating film.

It has been reported in Japanese Patent Publication No. 48-38617 and Japanese Patent Application Laid-Open No. 49-3454 that compositions prepared by blending various carboxylic acids as crosslinking agents with glycidyl group-containing acrylic polymers can be used in powder coatings.
It is described in Publication No. 6.

However, the coating film obtained when the aromatic polycarboxylic acid described therein is used alone generally lacks smoothness and flexibility, making it impractical, and when the aliphatic dicarboxylic acid is used alone, the coating film generally It has the disadvantage of being inferior in hardness and stain resistance, and it is not possible to obtain a fully satisfactory result in either case.

In view of these points, the present inventors have conducted intensive research and found that when saturated aliphatic dicarboxylic acids having 4 to 22 carbon atoms and trimellitic acid (anhydride) are used in a very limited specific range of proportions, coating It has been discovered that the smoothness, image clarity, hardness, stain resistance, etc. of the film can all be significantly improved, leading to the present invention.

That is, the present invention preferably uses a (β-methyl)glycidyl group-containing acrylic polymer in an amount of 75 to 96% by weight (hereinafter % indicates weight%), preferably 79 to 93%, and a weight ratio of 20:1 to 3:1, preferably 15%. : 1 to 5:1 mixture of saturated aliphatic dicarboxylic acid containing 4 to 22 carbon atoms and (anhydrous) trimellitic acid, preferably 4 to 25%, preferably 7 to 21%, for powder coatings. This invention relates to a resin composition.

In a bowing composition, if the usage ratio of even one of the constituent components deviates from the scope of the present invention, it will not be possible to obtain the excellent coating film that is a feature of the present invention.

The saturated aliphatic dicarboxylic acid used as part of the crosslinking agent of the present invention has 4 to 22 carbon atoms, preferably 5 to 13 carbon atoms, and includes, for example, adipic acid, pimelic acid,
Cono-phosphoric acid, azelaic acid, sebacic acid, decantate 1
There are 0-dicarboxylic acids and the like.

In addition, (methyl)glycidyl group-containing acrylic polymers (hereinafter simply referred to as polymers) are vinyl monomers having glycidyl groups and/or methylglycidyl groups, and other vinyl monomers (with a small amount of acrylic monomers). It is obtained by copolymerizing these monomers.

For monomers having a glycidyl group and vinyl monomers having a β-methylglycidyl group.

For example, (β-methyl)glycidyl ester of (meth)acrylic acid is included.

The proportion of these vinyl monomers in the polymer is usually 5
~50%, but in order to obtain a coating film with particularly excellent appearance and physical and chemical performance, the glycidyl group-containing vinyl monomer should be added in an amount of 5 to 20%, and the β-methylglycidyl group-containing vinyl monomer should be added in an amount of 5 to 20%. It is appropriate to keep the body weight at 5-20%.

Other vinyl monomers to be copolymerized with these monomers include monoesters of (meth)acrylic acid and monohydric or polyhydric alcohols, (meth:acrylonitrile, vinyl halides, vinyl acetate, vinyl alcohol, Styrene, tert-butylstyrene, etc. are included.

In particular, when the curing agent is trimellitic anhydride, the use of a hydroxyl group-containing vinyl monomer such as β-hydroxyethyl methacrylate makes it possible to introduce hydroxyl groups into the polymer.
It has the advantage of promoting ring opening of the acid anhydride group of trimellitic anhydride.

The same effect can also be achieved by using an unsaturated polyester having terminal hydroxyl groups as a modifier and polymerizing the raw vinyl monomer in its presence.

However, since the hydroxyl group is generated by the ring-opening reaction of the (β-methyl)glycidyl group, it is not necessarily necessary to take the trouble to introduce the hydroxyl group.

Although any known method can be used to produce the polymer, it is convenient to carry out solution polymerization and then remove the solvent, or to carry out suspension polymerization and then collect the produced polymer from house to house.

In the polymerization, for example, an azo compound such as azobisisobutylnitrile, a peroxide such as benzoyl peroxide, etc. can be used as an initiator.

A molecular weight regulator can also be used if necessary.

The molecular weight (number average) of the polymer is usually 3,000 to 30,000
Preferably it is 5,000 to 15,000, and the ring and ball softening point is usually 80 to 150°C, preferably 90 to 120°C.

To the thus formed composition of the present invention, various acid components, alkali components, and amines can be added to accelerate the curing reaction, and acrylic acid with a softening point of 50° C. or lower can be added to improve the smoothness of the coated surface. Chain alkyl ester polymers, fluorinated polymers, cellulose acetate butyrate, etc. can be added.

It goes without saying that other resins can be added to improve coating film performance.

For example, the salt resistance of the coating film can be improved by adding an epoxy resin.

Pigments, fillers, and additive systems can be mixed with the composition of the present invention to prepare a powder coating by any known method.

The resulting powder coating can be applied by any known method such as electrostatic spraying or fluidized dipping.

The present invention will be explained below according to examples.

"Parts" in the text indicate parts by weight.

Example 1 To a mixture of 200 parts of water and 73 parts of triammonium phosphate heated to 50°C, 2 parts of calcium acetate and 0.5 parts of sodium sulfite were added with stirring, the temperature was raised to 60°C, and styrene was dissolved in a nitrogen stream. 40 parts, inbutyl methacrylate 35 parts, glycidyl methacrylate 10 parts, β-methylglycidyl methacrylate 10 parts, β-hydroxypropyl methacrylate 5 parts, azobisisobutyl nitrile 4 parts, ter
1 part of t-butyl perbenzoate and 1 part of lauryl mercaptan were added, kept at the same temperature for 3 hours, and then gradually reduced to 80%
The product was heated to 105°C, kept at the same temperature for 15 hours, separated, washed with water and dried to give a softening point of 105°C and a molecular weight of 80.
000 polymer was obtained.

88 parts of this polymer, 10-dicarboxylic acid 10 decanoate
．． 5 parts of trimellitic anhydride, 15 parts of trimellitic anhydride, 0.5 parts of Modaflow (acrylic acid long-chain alkyl ester polymer fluidity adjuster manufactured by Monsando), and 50 parts of titanium oxide were heated at 90°C for 3 minutes using three rolls. After kneading, cool and crush, 1
The powder that passed through the 50-mesh wire mesh was used as a powder coating, which was applied to a mild steel plate by electrostatic spraying and baked at 200° C. for 20 minutes to obtain a coating film.

Example 2 35 parts of styrene, 40 parts of inbutyl methacrylate, β
- Using 5 parts of hydroxyethyl methacrylate, 10 parts of glycidyl methacrylate, and 10 parts of β-methylglycidyl methacrylate, a softening point of 1
A polymer having a molecular weight of 85,000 was obtained at 10°C.

88 parts of this polymer, decantated 10-dicarboxylic acid 10
．． A coating film was obtained in the same manner as in Example 1 using 5 parts of trimellitic acid, 1.5 parts of trimellitic acid, 0.5 parts of Modaflow, and 50 parts of titanium oxide.

Example 3 600 parts of isophthalic acid, 190 parts of trimethylolpropane
1 part, 360 parts of 1,6-hexanediol, and 20 parts of maleic anhydride were heated at 180°C for 2 hours and at 200°C for about 7 hours while stirring in an inert gas stream to reach a softening point of 1.
A polyester resin having a temperature of 00°C, a hydroxyl value of 120, and an acid value of 31 was obtained.

Further, 40 parts of styrene, 15 parts of inbutyl methacrylate, 10 parts of methyl nucleate, 10 parts of the above polyester resin, 10 parts of glycidyl methacrylate, and 15 parts of methylglycidyl methacrylate were used in the same manner as in Example 1, with a softening point of 109°C, A polymer having a molecular weight of 82,000 was obtained.

85 parts of the above polymer, decantated 13 parts of 10-dicarboxylic acid
part, 2 parts of trimellitic anhydride, 0.5 part of Modaflow,
A coating film was obtained in the same manner as in Example 1 using 50 parts of titanium oxide.

Example 4 Example 10 77 parts of polymer, 10 parts of Evicron 1050 (epoxy resin manufactured by Inu Nippon Ink Chemical Industry Co., Ltd.), 3.11 parts of Decanoate 10-dicarboxylic acid, 2 parts of trimellitic anhydride, 0.5 parts of Modaflow A coating film was obtained in the same manner as in Example 1 using 50 parts of titanium oxide.

Comparative Example 1 A coating film was obtained in the same manner as in Example 1 using 87 parts of Example 10 polymer, 13 parts of decantated 10-dicarboxylic acid, 0.5 parts of Modaflow, and 50 parts of titanium oxide.

Comparative Example 2 Example 10 Using 92 parts of polymer, 8 parts of trimellitic anhydride, 5 parts of Modaflow, and 50 parts of titanium oxide, Example 1
A coating film was obtained in the same manner as above.

Comparative Example 3 A coating film was prepared in the same manner as in Example 1 using 90 parts of the polymer of Example 10, 5 parts of decantate 10-dicarboxylic acid, 5 parts of trimellitic anhydride, 0.5 parts of Modaflow, and 50 parts of titanium oxide. Obtained.

Table 1 shows the performance of the baked coatings obtained on each side.

Stain resistance was determined by applying marker ink to the painted surface and wiping it off with absorbent cotton soaked in a mixed solvent of ethanol/petroleum benzine-515 after 24 hours at 30°C and judging by the degree of traces left.

Claims (1)

[Claims] 1 A weight ratio of 20:1 to 3:1 is added to 75 to 96% by weight of a (β-methyl)glycidyl group-containing acrylic polymer having a ring and ball softening point of 80 to 150°C and a number average molecular weight of 3000 to 30000. A resin composition for a powder coating comprising 4 to 25% by weight of a mixture of a saturated aliphatic dicarboxylic acid containing 4 to 22 carbon atoms and (anhydrous) trimellitic acid.