JPH08113758A - Coating resin composition - Google Patents

Abstract

PURPOSE: To obtain a resin composition for coating which gives coating film excellent in processability, hardness, resistancs to boiling water, corrosion and acid with superior scratching properties. CONSTITUTION: This resin composition comprises (A) a polyester prepared from the acid components: 50-100 mole % of aromatic dicarboxylic acid such as terephthalic acid and 50-0 mole % of other dicarboxylic acids such as 1,4- cyclohexanedicarboxylic acid, and the diol components: 20-85 mole % of an aliphatic diol such as 1,4-cyclohexanedimethanol and 80-15 mole % of a bisphenol A alkylene oxide adduct and less than 50 mole % of other glycols where the glass transition temperature is higher than 0 deg.C and the reduced viscosity is 0.2dl/g or higher and (B) a curing agent (suitably methoxylated methylolmelamine) at a weight ratio of 99/1-50/50 A/B.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a resin composition for paints which has excellent workability and hardness, exhibits excellent boiling water resistance, corrosion resistance, and acid resistance, and has excellent scratch resistance. The present invention relates to a resin composition for a paint, especially for a primer coating material for painted metal.

[0002]

BACKGROUND ART There are many paints currently used as resins for painted metals, such as polyester resins, alkyd resins, vinyl resins and silicone resin paints. There is. However, none of them satisfy all the required performances, and focusing on one performance inevitably causes defects in the other performances, and is restricted in use. Is the current situation. Building materials such as roofing materials and wall materials that require hardness, have excellent boiling water resistance, corrosion resistance, have a beautiful coating film appearance, and are required to have excellent scratch resistance,
Epoxy resin paint has been used as a primer for outdoor appliances such as storerooms, radiator units, refrigerators, etc.
It has good boiling water resistance, corrosion resistance, and solvent resistance, but it is still inadequate because of its extremely poor workability. Further, in VTRs, indoor appliances, home appliances, etc., which are required to have high processability, high molecular polyester is used as the top and primer paint. High molecular polyester resin coatings have high processability, hardness and boiling water resistance, corrosion resistance, acid resistance, and Erichsen adhesion, but scratch resistance is still insufficient.

For example, in JP-A-56-167767 and JP-A-3-217471, workability is excellent, and hardness, boiling water resistance, corrosion resistance, acid resistance and Erichsen adhesion are compatible. However, in any case, the scratch resistance is inferior, and in the field where the above-mentioned epoxy resin mainly for outdoor use is used, it is rarely used, and there is a demand for an urgent solution from the industry. There is.

[0004]

SUMMARY OF THE INVENTION In view of these problems, the present inventors have considered excellent workability, hardness, boiling water resistance, corrosion resistance,
As a result of diligent research on a coating resin having acid resistance and excellent scratch resistance, it was confirmed that copolymerization of an alicyclic glycol and a bisphenol A alkylene oxide adduct does not impair processability. The inventors have found that the scratch resistance is improved and have reached the present invention.

[0005]

That is, the present invention is as follows.
(A) Acid component is 50 to 100 mol% of aromatic dicarboxylic acid, other dicarboxylic acid is 0 to 50 mol%, and glycol component is 20 to 85 mol% of alicyclic glycol.
80 to 15 mol% of the bisphenol A alkylene oxide adduct represented by the general formula (I) of Chemical formula 2, 50 mol% or less of other glycols, a glass transition temperature of 0 ° C. or higher, and a reduced viscosity of 0.20 dl / g or higher. It is a resin composition for paints, characterized in that a polyester resin is mixed with a curing agent capable of reacting with the polyester resin.

Embedded image (In the formula, R ₁ and R ₂ are hydrogen or a methyl group, and m,
Each of n is a number of 1 or more and at the same time, 2 ≦ m + n ≦ 1.
It is 4. )

In the polyester resin (A) of the present invention, the acid component is 50 to 100 mol% of aromatic dicarboxylic acid, preferably 60 to 100 mol%, more preferably 70 to 100 mol%. 50 aromatic dicarboxylic acids
If it is less than mol%, good scratch resistance cannot be obtained, and hardness, boiling water resistance, corrosion resistance and acid resistance are poor.

Specific examples of the dicarboxylic acid copolymerizable with the polyester resin (A) of the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid and 2,6-naphthalenedicarboxylic acid.

Specific examples of other dicarboxylic acid copolymerizable with the polyester (A) of the present invention include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and 4-methyl. Hexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxy water-added bisphenol A, water-added dimer acid, water-added naphthalenedicarboxylic acid, tricyclodecanedicarboxylic acid and other fats Examples include cyclic dicarboxylic acids. Further, aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, and azelaic acid can be mentioned. Further, a polyvalent carboxylic acid such as trimellitic anhydride or pyromellitic dianhydride may be used in combination as long as the content of the invention is not impaired.

In the polyester (A) of the present invention, the glycol component is an alicyclic glycol in an amount of 20 mol% to 85 mol%, preferably 30 mol% to 80 mol%, and more preferably 40 mol% to 75 mol%. is necessary. If the alicyclic glycol is less than 20 mol%, the workability and scratchability will be poor. If the alicyclic glycol exceeds 85 mol%, boiling water resistance and corrosion resistance will be poor.

The alicyclic glycol used in the present invention is specifically 1,4-cyclohexanedimethanol, 1,
Examples thereof include 3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and water-added bisphenol.

In the polyester (A) of the present invention, the glycol component is 80 to 15 mol%, preferably 70 to 20 mol%, of the bisphenol A alkylene oxide adduct represented by the general formula (I). Preferably 60 to 25 mol% is required. The bisphenol A alkylene oxide adduct represented by the general formula (I) is 80
If it exceeds mol%, the workability is poor. If it is less than 15 mol%, scratch resistance, corrosion resistance and boiling water resistance are poor.
The bisphenol A alkylene oxide adduct represented by the general formula (I) has m + n of 14, preferably 2 to 8
And more preferably 2 to 4. If it exceeds 14, hardness, corrosion resistance, boiling water resistance, and scratch resistance become poor. If n + m is less than 2, reactivity during polymerization will be poor.

In the polyester (A) of the present invention, the other glycol component is 50 mol% or less, preferably 40 mol% or less, more preferably 30 mol% glycol.
It is the following. If it exceeds 50 mol%, chemical resistance, corrosion resistance,
Poor boiling water resistance.

The other glycol used in the present invention is specifically an alkylene glycol having 2 to 10 carbon atoms, specifically ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol,
Tetraethylene glycol, polyethylene glycol, polytetraethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1 , 5-pentanediol,
2-methyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol, 1,10- Decanediol and the like can be mentioned. Further, polyhydric polyols such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and polyglycerin may be used in combination as long as the contents of the invention are not impaired. In addition, 5-sulfoisophthalic acid, 4-
Metal salts of sulfonaphthalene-2,7-dicarboxylic acid, 5 [4-sulfophenoxy] isophthalic acid or 2-sulfo-1,4-butanediol, 2,5-dimethyl-3
Even if a dicarboxylic acid or glycol containing a sulfonic acid metal base such as a metal salt such as sulfo-2,5-hexanediol is used in a range of 5 mol% or less of the total acid or the total glycol component. Good.

After polymerizing the polyester resin in the polyester (A) of the present invention, trimellitic anhydride, phthalic anhydride, pyromellitic anhydride, succinic anhydride, 1,8-naphthalic anhydride, 1,2-cyclohexanedicarboxylic anhydride. An acid value may be imparted by post-adding an acid or anhydrous 3,3,4,4-benzophenonetetracarboxylic acid. By imparting an acid value, scratchability can be further improved. Preferably 50-300 equivalents / 10 ^6.
g.

The glass transition temperature of the polyester resin of the present invention is 0 ° C. or higher, preferably 20 ° C. or higher, more preferably 40 ° C. or higher. When the glass transition temperature is 0 ° C or lower, hardness, scratch resistance, boiling water resistance and corrosion resistance cannot be obtained.

The reduced viscosity of the polyester resin of the present invention is 0.20 dl / g or more, preferably 0.25 or more, more preferably 0.30 or more. Reduced viscosity is 0.2
If it is less than 0 dl / g, good workability cannot be obtained.

The coating resin composition of the present invention is used by blending a polyester resin (A) and a curing agent (B) capable of reacting with the polyester resin (A). In that case, the ratio of the polyester resin (A) to the curing agent (B) capable of reacting with it is (A) / (B) = 99.
It is used by blending at a ratio of / 1 to 50/50 (weight ratio). (A) / (B) is preferably 99/5 to 60/40
(Weight ratio). When (A) exceeds 99/1, scratch resistance and corrosion resistance are poor. If (A) is less than 50/50, workability becomes poor.

Examples of the curing agent (B) capable of reacting with the polyester resin (A) include alkyl etherified amino formaldehyde resins, epoxy compounds and isocyanate compounds. Alkyl etherified amino formaldehyde resin means, for example, formaldehyde or para formaldehyde alkylated with an alcohol having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, n-butanol and urea, N, N. -A condensation product with ethylene urea, dicyandiamide, aminotriazine, etc., and methoxylated methylol-N, N-ethylene urea,
Methoxylated methylol dicyandiamide, methoxylated methylol benzoguanamine, butoxylated methylol benzoguanamine, methoxylated methylol melamine, butoxylated methylol melamine, methoxylated / butoxylated mixed methylol melamine, butoxylated methylol benzoguanamine, etc. Preferred are methoxylated methylol melamine, butoxylated methylol melamine, or mixed methoxylated / butoxylated methylol melamine, which can be used alone or in combination.

Bisphenol A as an epoxy compound
Diglycidyl ether and its oligomer, hydrogenated bisphenol A diglycidyl ether and its oligomer, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-oxybenzoic acid diglycidyl ester, tetrahydrophthalic acid Acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol di Glycidyl ether, 1,6-hexanediol diglycidyl ether and polyalkylene glycol diglycidyl ethers, trime Butyric acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl propylene urea, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether , Triglycidyl ether of glycerol alkylene oxide adduct, and the like.

Further, as the isocyanate compound, there are aromatic and aliphatic diisocyanates and polyisocyanates having a valence of 3 or more, and either low molecular weight compounds or high molecular weight compounds may be used. For example, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate or trimer of these isocyanate compounds, and excess of these isocyanate compounds. The amount of the low molecular weight active hydrogen compound such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine or various polyester polyols, polyether polyols, polyamides Conflicts with high molecular weight active hydrogen compounds It includes terminal isocyanate group-containing compounds obtained by.

The isocyanate compound may be a blocked isocyanate. Examples of the isocyanate blocking agent include phenol, thiophenol,
Phenols such as methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, chlorophenol, acetoxime, methylethylketoxime, its oximes such as cyclohexanone oxime, alcohols such as methanol, ethanol, propanol, butanol, ethylene chlorohydride Phosphorus, halogen-substituted alcohols such as 1,3-dichloro-2-propanol, t-butanol, t-
Tertiary alcohols such as pentanol, ε-caprolactam, δ-valerolactam, γ-butyrolactam, β
-Lactams such as propyrolactam, and other aromatic amines, imides, acetylacetone,
Examples also include active methylene compounds such as acetoacetic acid ester and malonic acid ethyl ester, mercaptans, imines, ureas, diaryl compounds such as sodium bisulfite. The blocked isocyanate is obtained by subjecting the above-mentioned isocyanate compound and an isocyanate blocking agent to an addition reaction by a conventionally known appropriate method.

A known curing agent or accelerator selected depending on the type of the crosslinking agent may be used in combination.

The coating composition of the present invention exhibits sufficient performance just by coating and baking it on a steel plate, but when higher boiling water resistance, adhesion, etc. are required to be improved, epoxy is used. Resin, urethane resin, amide resin,
You may mix imide resin etc. Further, the coating composition of the present invention shows sufficient performance just by applying it to a steel plate and baking it, but when it is required to further improve weather resistance, etc., it is used as a top coat agent other than the present invention. You may use polyester resin, alkyd resin, acrylic resin, silicone resin, fluororesin, etc.

The baking temperature of the coating composition of the present invention is arbitrarily selected depending on the size and thickness of the steel sheet, the capacity of the baking furnace, the curability of the coating, and the like. A mixer such as a roll kneader, a ball mill and a blender is used for producing the coating composition. For coating, roller coating, roll coater, spray coating, electrostatic coating, etc. are appropriately selected.

The coating composition of the present invention comprises pigments such as titanium oxide, silica, sulphate sulfate, talc and various color pigments, anticorrosion pigments such as zinc chromate, strontium chromate, calcium chromate and red iron oxide, and glass fiber depending on the purpose and application. Additives such as wax can be added.

[0026]

EXAMPLES The present invention will be described below with reference to examples. In the examples, “parts” means “parts by weight”. Moreover, each measurement item followed the following method.

1. Reduced viscosity ηsp / c (dl / g) 0.10 g of polyester resin was dissolved in 25 cc of a mixed solvent of phenol / tetrachloroethane (weight ratio 6/4), and measured at 30 ° C.

2. Glass transition temperature It was measured at a temperature rising rate of 20 ° C./min using a differential scanning calorimeter (DSC). As a sample, 5 mg of the sample was placed in an aluminum pressing lid type container and crimped before use.

3. Acid value A sample of 0.2 g was precisely weighed and dissolved in 20 ml of chloroform. Then, it was determined by titration with 0.01 N potassium hydroxide (ethanol solution). Phenolphthalein was used as the indicator.

4. The film was immersed in an acid resistant 5% sulfuric acid aqueous solution at room temperature for 50 hours, and abnormalities in the appearance of the coating film were visually judged. (○: good, ×: bad)

5. Resistance to boiling water After immersion in boiling water for 10 hours, abnormalities in the appearance of the coating film were visually judged. (○: good, ×: bad)

6. Hardness The coated surface of the steel plate was measured according to JIS K-5400 using a high-grade pencil defined in JIS S-6006, and judged by the presence or absence of scratches.

7. Workability The coated steel sheet was bent 180 degrees, and cracks occurring in the bent portion were observed and judged with a 10 times magnifying glass. 3T indicates a case where three sheets having the same plate thickness are sandwiched in the bent portion, and 0T indicates a case where the plate is folded 180 degrees without sandwiching the plate.

8. Gloss 60 degree reflectance was measured.

9. Corrosion resistance After a cross-cut was made on the surface of the coating film with a knife, the state of corrosion was measured at 35 ° C after 1000 hours of a 5% -NaCl salt spray test. (Corrosion width from cross cut (unit: m
The smaller m) is, the better the result is.)

10. Scratchability A pencil having a hardness of 7H was attached to a pencil hardness tester, a load of 2 kg was applied, the coating film was scratched by the method of JIS-K5400, and peeling of the coating film was visually judged. (◎ Excellent, ○ Good, × Poor)

Preparation of Top Coat 80 parts of commercially available high molecular weight polyester Byron 300 (manufactured by Toyobo Co., Ltd.), 80 parts of a mixture of 20 parts of the same Byron 200, 117 parts of cyclohexanone and 116 parts of Solvesso-150 were used. The mixture was poured under stirring at ℃ and dissolved for about 3 hours. To 100 parts of solid content in the obtained solution, 125 parts of titanium oxide, methyl etherified methylol melamine (trade name: Sumimar M-40S, nonvolatile content 80%,
Sumitomo Chemical Co., Ltd. 25 parts, and 2.5 parts of 10% benzyl alcohol solution of p-toluene sulfonic acid were added and dispersed for 5 hours with a glass bead type high-speed shaker to obtain a coating for a coated steel sheet (a) ) Was adjusted.

Synthesis Example (A) 200 parts of dimethyl terephthalic acid and dimethyl isophthalic acid were placed in a reaction vessel equipped with a stirrer, a condenser and a thermometer.
200 parts, 1,4-cyclohexanedimethanol 13
4 parts, bisphenol A ethylene oxide 2.3 mol addition product, 331 parts, ethylene glycol 144 parts, tetrabutyl titanate 0.255 parts were charged, 160 parts
The esterification reaction was performed from 4 ° C to 250 ° C over 4 hours. Then, the pressure in the system is gradually reduced to 5 for 50 minutes.
The pressure was reduced to mmHg, and a polycondensation reaction was performed at 260 ° C. for 60 minutes under a vacuum of 0.3 mmHg or less. As a result of composition analysis such as NMR, the obtained copolyester (A) was found to have a molar ratio of acid components of terephthalic acid / isophthalic acid =
50/50, and the glycol component has a molar ratio of 1,4-
Cyclohexanedimethanol / Bisphenol A ethylene oxide 2.3 mol adduct / ethylene glycol =
It was 45/50/5, and when the reduced viscosity was measured, it was 0.35 dl / g and the acid value was 12 equivalents / 10 ⁶ g,
The glass transition temperature was 69 ° C. The results are shown in Table 1.

Hereinafter, Table 1 was obtained by the method according to the above-mentioned synthesis example.
-Polyester resins (B) to (F) having the compositions shown in Table 3 were synthesized. (G) to (M) in Table 4 are comparative polyesters.

Example 1 100 parts of polyester resin (A) was added to cyclohexanone 7
80 parts in a mixed solvent of 5 parts and Solvesso-150 in 75 parts.
The mixture was poured under stirring at ℃ and dissolved for about 3 hours. 40 parts of titanium oxide, 40 parts of strontium chromate, 40 parts of methyl etherified methylol melamine (trade name: Sumimal M-40S, non-volatile content 80%, manufactured by Sumitomo Chemical Co., Ltd.) with respect to 100 parts of solid content in the obtained solution. Parts and 2.5 parts of a 10 wt% benzyl alcohol solution of p-toluenesulfonic acid were added and dispersed for 5 hours with a glass bead type high-speed shaker to obtain a coating composition.

This coating composition was applied to a zinc iron phosphate-coated steel sheet having a thickness of 0.5 mm so as to have a film thickness of 8 μ, and then baked at 210 ° C. for 50 seconds. The top coating composition obtained in Reference Example was further applied to the obtained coating plate to a thickness of about 18 μm, and then baked at 230 ° C. for 60 seconds. The resulting coating film has good processability and hardness, and exhibits coating film properties excellent in boiling water resistance, corrosion resistance, and acid resistance.
It had excellent scratch resistance. The test results are shown in Table 5.

In the same manner as described below, Examples 2 to 9 and Comparative Example 1
The coating compositions Nos. 9 to 9 were prepared, applied and baked. Table 5 to Table 8 show the test results of the obtained coated steel sheet. However, the compounding ratio of the paint was expressed in terms of solid content.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

EFFECT OF THE INVENTION The coating composition of the present invention has a coating film having good workability and hardness, and exhibits coating film properties excellent in boiling water resistance, corrosion resistance and acid resistance. It has excellent scratch resistance that could not be obtained with conventional technology, and it is used for home appliances including outdoor, building materials such as roofing materials and wall materials, storerooms, outdoor equipment such as radiator units, VTRs, refrigerators, etc. It can meet the high quality requirements in the field.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masami Oka 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd.

Claims (1)

[Claims] 1. The (A) acid component is an aromatic dicarboxylic acid 50.
˜100 mol%, other dicarboxylic acid is 0˜50 mol%, glycol component is alicyclic glycol 20 mol% ˜
85 mol%, 80 to 15 mol% of bisphenol A alkylene oxide adduct represented by the following general formula (I) of Chemical formula 1, 50 mol% or less of other glycols, glass transition temperature of 0 ° C. or higher, and reduced viscosity of 0. 20% dl / g or more of the polyester resin (A) and the curing agent (B) capable of reacting with the polyester resin (A) are blended at a ratio of (A) / (B) = 99/1 to 50/50 (weight ratio). A characteristic resin composition for paints. Embedded image (In the formula, R ₁ and R ₂ are hydrogen or a methyl group, and m,
Each of n is a number of 1 or more and at the same time, 2 ≦ m + n ≦ 1.
It is 4. )