JP3130032B2 - Paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a fluorine-modified resin suitable for a pre-coated metal coating material which forms a coating film having excellent stain resistance, hardness and flexibility. The present invention relates to a coating composition comprising an amino resin and a polyester resin or an acrylic resin.

(Prior art) A class of electrical products called light electrical products, such as paints for pre-coated metals used in refrigerators and washing machines,
Excellent stain resistance and high hardness are required. In addition, due to problems in the manufacture of coated steel sheets, the coating applied to the pre-coated metal requires flexibility and workability that can withstand subsequent pressing, bending, punching, etc. Required a coating film made of a flexible and highly flexible resin. However, such a coating film generally has insufficient hardness and poor stain resistance, and thus has a practical problem. On the other hand, a coating film having a hardness of a certain degree or more has problems such as cracking and peeling due to press work, bending work, punching work, etc., although the stain resistance is good, but the flexibility and flexibility are insufficient. Have.

Examples of this type of precoat metal paint include amino-acrylic resin, amino-alkyd resin, amino-
There are many types such as oil-free polyester resin type and vinyl resin type, but at present it is said that all of them are subject to restrictions on use for the reasons described above. The reality is that we cannot meet these demands.

(Problems to be Solved by the Invention) As a result of repeated studies to solve the above problems, the present inventors have modified fluorine-containing alcohol and amino resin to obtain a fluorine-modified amino-polyester resin or fluorine-modified amino-polyester resin. It has been found that many fluorine-modified amino resins are unevenly distributed in the surface layer of the coating film formed from the modified amino-acrylic resin system.

It has been found that a coating composition comprising such a fluorine-modified amino-polyester resin or a fluorine-modified amino-acrylic resin forms a coating film having excellent stain resistance and hardness without impairing flexibility, and led to the present invention. Was.

[Configuration of the invention]

(Means for Solving the Problems) The present invention relates to a fluorine-modified amino resin obtained by subjecting 100 parts by weight of an amino resin to an etherification reaction of 0.1 to 100 parts by weight of a fluorine-containing alcohol, and 5 to 100 parts by weight of a number average molecular weight. The present invention relates to a coating composition comprising 10,000 to 100,000 100 parts by weight of a polyester resin or an acrylic resin.

As the amino resin used in the present invention, a melamine resin,
Examples thereof include a urea resin, a benzoguanamine resin, and a glycoluril resin, and those having a methylol group or an alkoxymethyl group and further having an imino group can be used, and these can be used alone or in combination.

The fluorine-modified amino resin used in the present invention,
It is obtained by modifying the amino resin with a fluorine-containing alcohol in an amino resin solution having a methylol group or an alkoxymethyl group in the presence of a catalyst. That is, a methylol group in the amino resin and a hydroxyl group in the fluorine-containing alcohol are dehydrated and condensed and etherified, or an alkoxymethyl group in the amino resin and a hydroxyl group in the fluorine-containing alcohol are de-alcoholized. It has been subjected to a chemical reaction (substitution with ether).

Specific examples of the fluorine-containing alcohol include the following.

FC ₆ H ₄ C ₂ H ₄ OH FC ₆ H ₄ OH FC ₂ H ₄ OH CF ₃ CH ₂ OH CF ₃ C ₆ H ₄ CH ₂ OH CF ₃ C ₆ H ₄ OH (CF ₃ ) ₂ CHOH The amount is 0.1 to 100 parts by weight, preferably 0.5 to 50 parts by weight, based on 100 parts by weight of the amino resin.
When the amount is less than 0.1 part by weight, a sufficient effect on the stain resistance cannot be obtained. On the contrary, when the amount exceeds 100 parts by weight, the compatibility with the amino resin becomes poor and the resin is separated.

As the dibasic acid which is a constituent component of the polyester resin, generally known raw materials can be used. Specific examples thereof include isophthalic acid, terephthalic acid, phthalic anhydride, dimethyl isophthalate, dimethyl terephthalate, adipic acid, azelaic acid, sebacic acid, glutaric acid, and hexahydrophthalic anhydride.
Can be used for more than species. Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, trimethylolpropane, propylene glycol, dipropylene glycol, 1,6-hexanediol, neoventil glycol, hydrogenated bisphenol A, 1,4- Butanediol, 1,4-cyclohexanediol, 2,2,4-trimethylpentane1,3-diol, polyethylene glycol, etc., and these can be used alone or in combination of two or more.

The molecular weight of the saturated polyester resin obtained from the raw materials is preferably in the range of 10,000 to 100,000. If it is less than 10,000, the processability of the coating film is poor, and if it is more than 100,000, the viscosity increases and the handling becomes difficult.

As an acrylic resin, in considering the workability of the coating film,
It is preferable to use an acrylic polyol resin. As the acrylic polyol resin, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol or acrylic acid,
Hydroxyl-containing monomers which are reaction products of unsaturated carboxylic acids such as methacrylic acid, maleic acid, fumaric acid, and itaconic acid with ethylene glycol, ethylene oxide, propylene glycol, propylene oxide, etc., and methyl acrylate and acrylic acid Acrylic esters such as ethyl, n-propyl acrylate and 2-ethylhexyl acrylate; methacrylic esters such as ethyl methacrylate, n-propyl methacrylate and 2-ethylhexyl methacrylate; styrene monomers; acrylic acid And methacrylic acid, acrylamide, ethylene, glycidyl methacrylate, etc., by copolymerizing one or two or more copolymerizable α, β-ethylenically unsaturated monomers.

The molecular weight of the acrylic polyol resin obtained from the raw materials is preferably in the range of 10,000 to 100,000. If it is less than 10,000, the processability and chemical resistance of the coating film are inferior. If it is more than 100,000, the viscosity increases and the handling becomes difficult.

The method for obtaining the fluorine-modified amino resin in the present invention includes (1) a method in which an amino resin and a fluorine-containing alcohol are dissolved in an organic solvent in the presence of a catalyst and heating, and (2) a method in which the amino resin and a polyester resin or acryl in the presence of a catalyst are present. There is a method in which a fluorine-containing alcohol is dissolved in a resin mixed solution and heated. In the latter method, it is considered that the reaction between the amino resin and the fluororesin is delayed due to the influence of the polyester resin or the acrylic resin in the solution, and it is considered that the effect of stain resistance is not obtained as much as the former method. Reaction temperature is 60
To 150 ° C, preferably 100 to 150 ° C. Heating at 60 ° C or lower does not provide a sufficient effect on stain resistance, while heating at 150 ° C or higher produces a gel during the reaction.

The coating composition of the present invention is a fluorine-modified amino resin 5 to 100
Parts by weight and polyester resin or acrylic resin 10
0 parts by weight, preferably 10 to 50 parts by weight of a fluorine-modified amino resin and 100 parts by weight of a polyol resin (polyester polyol resin). When the content of the fluorine-modified amino resin is 10 parts by weight or less, the effect on hardness and stain resistance is not obtained. Conversely, when the content is 50 parts by weight or more, processability is poor.

Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene, ketone solvents such as methyl ethyl ketone and cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, and other alcohol solvents such as ethanol and butanol. It may be a mixed solvent.

Further, a thermosetting paint can be prepared by blending generally known pigments, fillers, additives, catalysts and the like.

Hereinafter, the present invention will be described with reference to examples. In the examples, “parts” means “parts by weight” and “%” means “% by weight”.

Production Example 1 Synthesis of fluorine-modified amino resin (a-1) Melamine resin [trade name, manufactured by Mitsui Cyanamid Co., Ltd.]
Cymer 325) 100 parts, fluorine-containing alcohol [FC ₆ H ₄ C ₂ H
₄ OH] 4.1 parts, paratoluenesulfonic acid 0.86 parts, cellosolve acetate 63.6 parts were charged into a reaction vessel and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to convert the fluorine-modified amino resin (a-1). Obtained.

Production Example 2 Synthesis of fluorinated amino resin (a-2) 100 parts of melamine resin (trade name: Cymel 272, manufactured by Mitsui Cyanamid Co., Ltd.), 4.1 parts of fluorine-containing alcohol used in Example 1, 0.86 parts of paratoluenesulfonic acid And 63.6 parts of cellosolve acetate were charged into a reaction vessel and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to obtain a fluorine-modified amino resin (a-2).

Production Example 3 Synthesis of fluorine-modified amino resin (a-3) 100 parts of melamine resin (trade name: Cymel 272, manufactured by Mitsui Cyanamid Co., Ltd.), 4.1 parts of fluorine-containing alcohol used in Example 1, 0.86 parts of paratoluenesulfonic acid And 63.6 parts of cellosolve acetate were charged into a reaction vessel and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to obtain a fluorine-modified amino resin (a-3).

Production Example 4 Synthesis of fluorine-modified amino resin (a-4) 100 parts of melamine resin (trade name: Cymel 272, manufactured by Mitsui Cyanamid Co., Ltd.), 8.20 parts of fluorine-containing alcohol used in Example 1, and 0.86 parts of paratoluenesulfonic acid And 63.6 parts of cellosolve acetate were charged into a reaction vessel and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to obtain a fluorine-modified amino resin (a-4).

Production Example 5 Synthesis of fluorine-modified amino resin (a-5) 100 parts of melamine resin (trade name: Cymel 254, manufactured by Mitsui Cyanamid Co., Ltd.), 5 parts of fluorine-containing alcohol used in Example 1, 1.05 parts of paratoluenesulfonic acid And 100 parts of cellosolve acetate were charged into a reaction vessel, and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to obtain a fluorine-modified amino resin (a-5).

Production Example 6 Synthesis of fluorinated amino resin (a-6) 100 parts of melamine resin (trade name: Cymel 703, manufactured by Mitsui Cyanamid Co., Ltd.), 4.1 parts of fluorine-containing alcohol used in Example 1, 0.86 parts of paratoluenesulfonic acid And 63.6 parts of cellosolve acetate were charged into a reaction vessel and heated at 110 to 115 ° C. for 2 hours while stirring under a nitrogen stream to obtain a fluorine-modified amino resin (a-6).

Production Example 7 Synthesis of polyester resin (b-1) 492 parts of dimethyl terephthalate, ethylene glycol 2
52 parts, Neobentyl glycol 281 parts, zinc acetate 0.07
And 0.15 part of trimonium antimony were charged into a reaction vessel, and the mixture was heated to 160 to 220 ° C. while stirring under a nitrogen stream to carry out a transesterification reaction. After distilling off a theoretical amount of methanol, 411 parts of isophthalic acid and 209 parts of azelaic acid were charged into the reaction vessel and esterified at 180 to 240 ° C. When the acid value became 20 or less, the pressure in the reaction vessel was gradually reduced, and polymerization was carried out under reduced pressure at 1 mmHg or less at 240 ° C. for 3 hours to obtain a hydroxyl group-containing saturated polyester (b-1). Polyester (b-1) had a hydroxyl value of 9, an acid value of 1.2 and a molecular weight of 12,000.

Production Example 8 Synthesis of polyester resin (b-2) 492 parts of dimethyl terephthalate, ethylene glycol 2
52 parts, Neobentyl glycol 281 parts, zinc acetate 0.07
And 0.15 part of trimonium antimony were charged into a reaction vessel, and the mixture was heated to 160 to 220 ° C. while stirring under a nitrogen stream to carry out a transesterification reaction. After distilling off the theoretical amount of methanol, 411 parts of isophthalic acid and 209 parts of azelaic acid were charged into the reaction vessel and esterified at 180 to 240 ° C. When the acid value became 20 or less, the pressure in the reactor was gradually reduced, and polymerization was carried out under reduced pressure at 260 ° C. and 1 mmHg or less for 6 hours to obtain a hydroxyl group-containing saturated polyester (b-2). Polyester (b-2) had a hydroxyl value of 9, an acid value of 1.2 and a molecular weight of 30,000.

Production Example 9 Synthesis of acrylic resin (c-1) 33 parts of methyl methacrylate, 5 parts of styrene, 13.5 parts of hydroxyethyl methacrylate, 48 parts of 2-ethylhexyl methacrylate, 0.5 part of acrylic acid, 1.5 parts of azobisisobutyronitrile Into a reaction vessel charged with 50 parts of xylol and 51.5 parts of butyl acetate at 78-80 ° C. with stirring over 2 hours, polymerize, and further heat at 80 ° C. for 2 hours to continue acrylic polyol. Resin (c-1) was obtained. Acrylic resin (c-1) has a hydroxyl value of 58 and a molecular weight of 21,000 to 23,0
00.

Production Example 10 Synthesis of acrylic resin (c-2) 33 parts of methyl methacrylate, 5 parts of styrene, 13.5 parts of hydroxyethyl methacrylate, 48 parts of 2-ethylhexyl methacrylate, 0.5 part of acrylic acid, 0.5 part of azobisisobutyronitrile Into a reaction vessel charged with 50 parts of xylol and 51.5 parts of butyl acetate over 2 hours with stirring at 78-80 ° C, and further heated at 80 ° C for 3 hours while continuing to heat the acrylic polyol resin. (C-2) was obtained. Acrylic resin (c-2) has a hydroxyl value of 58 and a molecular weight of 52,000 to 55,000
Met.

Examples 1 to 13 and Comparative Examples 1 to 5 The fluorine-modified amino resin obtained in Production Examples 1 to 6, the polyester resin obtained in Production Examples 7 to 8, and Production Examples 9 to
Using the acrylic resin obtained in Step 10, a paint was prepared with the paint composition shown in Table 1, and a physical property test of the baked cured coating film was conducted.

The baking of the paint was performed at 200 ° C. for 10 minutes by applying the paint on a bond steel plate at a thickness of 20 μm. Table 1 shows the results.

 The judgment of the test result was performed as follows.

(1) Pencil hardness It was measured by JIS K 5400 using Mitsubishi Uni.

(2) Workability The painted plate was bent 180 ° and pressed.

Evaluation ：: No cracks: 1: 1/3 cracks ：: Cracks on the entire surface (3) Stain resistance After 24 hours, traces of magic ink (blue, black, red) on test pieces are wiped off with ethanol.

(4) Acid resistance 3 ml of 5% HCl solution was dropped on the coated surface, left standing for 24 hours, then washed with water and visually evaluated for changes in the coated surface. Evaluation 評 価: No abnormality 異常: Slight discoloration was observed
Δ: Discoloration observed X: Swelling observed (5) Alkali resistance 3 ml of a 5% NaOH solution was dropped on the coated surface, allowed to stand for 24 hours, then washed with water, and the change in the coated surface was visually judged. Evaluation is based on acid resistance.

〔The invention's effect〕

The fluorine-modified amino resin composition of the present invention is obtained by modifying an amino resin with a fluorine-containing alcohol, and does not impair the workability and hardness of the coating film and enhances stain resistance.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 12/00-12/46 C09D 161/20-161/32 C09D 133/00-133/16 C09D 167/00-167 / 08

Claims (1)

(57) [Claims] 1 to 5 parts by weight of a fluorine-modified amino resin obtained by etherifying 100 parts by weight of an amino resin with 0.1 to 100 parts by weight of a fluorine-containing alcohol, and a polyester resin or acrylic having a number average molecular weight of 10,000 to 100,000. A coating composition comprising 100 parts by weight of a resin.