JPH027343B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy coating resin composition that forms a cured coating film with excellent curability, flexibility, and adhesion at low temperatures. Bisphenol A-based resins with an epoxy equivalent of 1000 or more have hydroxyl groups that can react with isocyanate groups,
It has three or more in one molecule and can cause a crosslinking reaction with polyisocyanate to form a cured coating film. At this time, since the epoxy group does not react with the isocyanate group, it may be modified with dialkanolamine or monocarboxylic acid, but a small amount of epoxy group may remain as it does not have an adverse effect on the coating film. This cured coating film is similar to that obtained when using an amine-based cross-linking agent, and has excellent corrosion resistance, adhesion, and chemical resistance, which are characteristics of epoxy resins, and has better low-temperature curing properties than when using an amine-based cross-linking agent. It is excellent and is used as a vehicle for general rust prevention and heavy rust prevention, and is particularly widely used when low-temperature curability is required. However, this type of cured coating film is generally very hard, lacks the flexibility required for many applications, and has the drawbacks of poor impact resistance and bending resistance. Generally, cured coatings obtained from bisphenol A-based epoxy resins have the disadvantage of lacking flexibility, but in order to improve this, epoxy resins have been made with dimer acids (dimer acids made by heating and polymerizing unsaturated fatty acids). dibasic acids of the body, e.g. Versadime 216, 282
(both manufactured by Henkel Japan, trade name) are commercially available. ) or a butadiene/acrylonitrile copolymer with a carboxyl group at the end. Typical epoxy resins modified with dimer acid include Epotote YD172 (trade name, manufactured by Shato Kasei Co., Ltd.) and Epiclon 1600 (manufactured by Dainippon Ink and Chemicals Co., Ltd.).
Although they have improved flexibility, smoothness, dilutability with organic solvents, pigment dispersibility, etc., they have the disadvantage of impairing the adhesion characteristic of epoxy resins. Also, butadiene has a carboxyl group at the end. Modification with acrylonitrile copolymer is disclosed in Japanese Patent Application Laid-open Nos. 55-84371 and 56-84.
No. 122823 and has flexibility without compromising adhesion. However, if a butadiene/acrylonitrile copolymer having sufficient terminal carboxyl groups is used to achieve this property, water resistance, corrosion resistance, and dilutability to organic solvents will deteriorate. Furthermore, a butadiene/acrylonitrile copolymer having a carboxyl group at the end is more expensive than dimer acid or epoxy resin, so its use inevitably increases costs. The present inventors conducted various studies in order to improve the drawbacks of these conventional flexible epoxy resins, and as a result, for 100 parts by weight of bisphenol A-based epoxy resin with an epoxy equivalent of 170 to 1000,
1 mole or less per equivalent of the remaining epoxy group of the modified epoxy resin obtained by reacting 10 to 1000 parts by weight of dimer acid and 5 to 40 parts by weight of a butadiene-acrylonitrile copolymer having a terminal carboxyl group. Invented a resin composition for coatings whose main component is a polyisocyanate with an isocyanate group equivalent of 0.7 to 1.3 added to 1 equivalent of hydroxyl groups of an epoxy-modified polyol resin obtained by reacting dialkanolamine or monocarboxylic acid. However, unlike conventional products, this product gives satisfactory results in all aspects of flexibility, adhesion, water resistance, corrosion resistance, low temperature curability, and dilutability with organic solvents. In the present invention, the reason why bisphenol A-based epoxy resin having an epoxy equivalent of 170 to 1000 is used as the epoxy resin is because if the epoxy equivalent is 1000 or more, the modified epoxy resin becomes highly viscous and is not practical.
Furthermore, it is impossible to synthesize bisphenol A-based resins with less than 170 bifunctional epoxy groups. Typical commercial products include Epicote 815,
828, 834, 1001, 1004 (manufactured by Yuka Ciel Epoxy Co., Ltd.)
Product name), Epotote YD-115, 128, 134, 011,
014 (manufactured by Toto Kasei Co., Ltd., product name). Butadiene/acrylonitrile copolymer with carboxyl groups at the ends is a linear polymer with carboxyl groups at both ends of the molecule, and has a molecular weight of 2000 to 5000.
Typical commercially available products include Hiker C TBN1300×8, 1300×9 (manufactured by BF Gutsudoritsu Co., Ltd., trade name), Naipaul DN601 (manufactured by Nippon Zeon Co., Ltd., trade name), etc. (Examples) For simplicity, it is expressed as liquid rubber.) Examples of dialkanolamines to be reacted with the residual epoxy groups include diethanolamine and diisopropanolamine, and examples of monocarboxylic acids include aromatic acids such as benzoic acid and paratertiary butylbenzoic acid. Aliphatic monocarboxylic acids include monocarboxylic acids, acetic acid, propionic acid, coconut oil fatty acids, soybean oil fatty acids, tall oil fatty acids, and castor oil fatty acids. In the present invention, the dimer acid is limited to 10 to 100 parts by weight relative to 100 parts by weight of the epoxy resin, because if it is less than 10 parts by weight, sufficient flexibility cannot be obtained, and if more than 100 parts by weight is used, This is because the inherent adhesion, corrosion resistance, and chemical resistance of the epoxy resin are impaired. In addition, butadiene/acrylonitrile containing a carboxyl group at the end was limited to 5 to 40 parts by weight because less than 5 parts by weight has little effect on flexibility, adhesion, and low-temperature curability, and more than 40 parts by weight If used, the water resistance and corrosion resistance will deteriorate, the viscosity will become high and workability will be poor, the rigidity of the epoxy resin will be impaired, and it will be uneconomical (butadiene-acrylonitrile copolymers with terminal carboxyl groups are expensive). ) Dialkanolamine or monocarboxylic acid to be reacted with the remaining epoxy groups is added to the remaining epoxy groups.
The reason why the amount is set to 1 mole or less based on the equivalent is that the modified epoxy resin modified with the dimer acid and the butadiene-acrylonitrile copolymer having a terminal carboxyl group contains hydroxyl groups that can react with isocyanate groups. It may be used as is as a polyol resin together with a polyisocyanate compound, but it can be obtained by further reacting with dialkanolamine or monocarboxylic acid at a ratio of 1 mole or less per equivalent of residual epoxy groups that do not react with isocyanate groups. This is because when the polyol resin used together with a polyisocyanate compound is used, a cured coating film having even better chemical resistance and water resistance can be obtained. Now, in order to make the epoxy modified polyol resin referred to in the present invention, for example, the epoxy equivalent is 170 to 1000.
To 100 parts by weight of bisphenol A-based epoxy resin, 10 to 100 parts by weight of dimer acid and 5 to 40 parts by weight of a butadiene-acrylonitrile copolymer having a carboxyl group at the terminal were added at 130 to 200°C.
The reaction is carried out in the presence of a catalyst such as a tertiary amine such as triethylamine or benzyldimethylamine, a quaternary ammonium salt such as tetramethylammonium chloride, or a trisubstituted phosphine such as triphenylphosphine. It can be easily produced by reacting 1 mole or less of dialkanolamine or monocarboxylic acid per equivalent of epoxy group at 130 to 200°C. Next, the polyisocyanate compound as used in the present invention is a compound having two or more isocyanate groups, such as tolylene diisocyanate (TDI),
Polyisocyanate prepolymers such as diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMDI), xylene diisocyanate (XDI), isophorone diisocyanate (IPDI), their polyol adducts, and polymers, and polyisocyanate prepolymers such as polyol adducts and polymers of these, and those in which the isocyanate active group is phenol. These include blocked isocyanate compounds blocked with alcohol or alcohol. The mixing ratio of the above-mentioned epoxy-modified polyol resin and polyisocyanate is preferably such that the hydroxyl groups of the former are equal to the isocyanate groups of the latter, but this is not always necessary; for example, even if isocyanate groups remain. Moisture in the air contributes to the hardening of the paint film. It goes without saying that pigments and other conventional additives may be further added to the coating resin composition of the present invention as required. Example 1 In a flask equipped with a thermometer, stirrer, and reflux condenser as described in Contents 1, 100 g of bisphenol A-based epoxy resin "Epicote 1004" (epoxy equivalent 950, manufactured by Yuka Ciel Epoxy Co., Ltd., trade name) was added. , dimer acid "Versadime 216" (manufactured by Henkel Japan, trade name)
15g, liquid rubber (butadiene-acrylonitrile copolymer with a carboxyl group at the end) "Hiker CTBN1300 x 8 (manufactured by BF Gutdrich, trade name) 15g, tetramethylammonium chloride
0.1g, kept at 150℃ for 5 hours with stirring,
87 g of xylene was added to obtain a modified epoxy resin solution (A) having a hydroxyl value of 184. Next, 45 g of red iron, 12 g of calcium carbonate, and 24 g of talc were added to 100 g of (A), and after thorough mixing, urethane prepolymer "Vancenate A-81 (NCO 9%, manufactured by Harima Kasei Kogyo Co., Ltd.)
Product name) 92g (equivalent ratio of isocyanate group to hydroxyl group 1:1), diluted with a mixed solvent of equal weights of toluene and ethyl acetate to the extent that it can be spray painted, and JIS-G314 0.7mm x 150mm x 70mm. spray painted on mild steel plate. Dry at 20℃ for 3 days to reduce film thickness.
A cured coating film (1) of 100μ was obtained. Example 2 Using the same equipment as in the above example, bisphenol A-based epoxy resin “Epicote 1001” (epoxy equivalent
450, product name 100g and "Versa Dime 216" 15g,
15g of liquid rubber “Hiker CTBN1300×8”
0.1 g of tetramethylammonium chloride was kept at 150°C for 5 hours with stirring, then 10 g of diisopropanolamine (0.5 mol per equivalent of residual epoxy group) was added and kept at 170°C for 5 hours while stirring. Thereafter, 107 g of xylene was added to obtain an epoxy-modified polyol resin solution (B) with a hydroxyl value of 227 and a solid content of 60%. The subsequent operations were the same as in Example 1, except that the amount of "Vancenate A-81" used as a crosslinking agent was 91 g (equivalent ratio of isocyanate groups to hydroxyl groups 0.8:1), and a cured coating film with a film thickness of 100 μm was obtained. I got (2). Example 3 Using the same equipment as in Example 1, bisphenol A-based epoxy resin “Epicote 828” (epoxy equivalent: 175,
Product name) 100g, "Versadime 216" 50g, liquid rubber "Nipol601" (manufactured by Nippon Zeon Co., Ltd., product name) 25
g, 0.1 g of tetramethylammonium chloride,
After keeping at 150℃ for 5 hours with stirring, benzoic acid
41 parts (0.9 mol per equivalent of remaining epoxy group) was added and kept at 170°C for 5 hours with stirring, and xylene 144
g was added to obtain an epoxy-modified polyol resin (C) containing 60% solid content of 169 hydroxyl groups. In the subsequent operations, "Bansate A-" was used as a crosslinking agent.
A cured coating film (3) with a film thickness of 100 μm was obtained in the same manner as in Example 1, except for blending 101 g of “81” (equivalent ratio of isocyanate groups to hydroxyl groups: 1.2:1). Example 4 Using the same equipment as in Example 1 above, bisphenol A
epoxy resin “Epicote 128” (epoxy equivalent
190, manufactured by Toto Kasei Co., Ltd., product name) 100g, "Versadime 216" 80g, liquid rubber "Hiker CIBN1300"
×8” 10g, tetramethylammonium chloride
After keeping 0.1g at 150℃ for 5 hours with stirring, 59g of tall oil fatty acid (per equivalent of residual epoxy group)
0.9 mol) was added thereto, and the mixture was kept at 170° C. for 5 hours with stirring, and 166 g of xylene was added to obtain an epoxy-modified polyol resin solution (D) having a hydroxyl value of 139. In the subsequent operations, 69g of "Vancenate A-81" was added as a crosslinking agent ((equivalent ratio of isocyanate to hydroxyl group 1:1))
Everything else was the same as in Example 1, and the film thickness was 100μ.
A cured coating film (4) was obtained. Example 5 Add 30 g of "Epicoat 1004" to 70 g of the epoxy-modified polyol resin solution obtained in Example 3 above, heat and dissolve, then add 20 g of xylene to give a hydroxyl value of 179.
A resin solution (E) containing 60% solid content was obtained. In the subsequent operations, "Vancenate A" was used as a crosslinking agent.
A cured coating film (5) with a film thickness of 100 μm was obtained in the same manner as in Example 1, except that 89 g of “-81” was used (equivalent ratio of isocyanate groups to hydroxyl groups: 1:1). Comparative Example 1 Using the same equipment as in Example 1 above, bisphenol A
100g of epoxy resin “Epicote 1001”, 20g of “Versadime 216”, liquid rubber “Hiker”
After stirring 3 g of "CTBN1300 x 8" and 0.1 g of tetramethylammonium chloride at 150℃ for 5 hours, 10 g of diisopropanolamine was added.
(0.5 mol based on the remaining epoxy groups) and kept at 170°C for 5 hours with stirring, then added 89 g of xylene to obtain an epoxy-modified polyol resin solution (F) with a hydroxyl value of 273 and a solid content of 60%. (equivalent ratio of isocyanate groups to hydroxyl groups 1:1). Thereafter, the same operations as in Example 1 were carried out except that 136 g of "Vancenate A-81" was added as a crosslinking agent to obtain a cured coating film (ratio 1) with a film thickness of 100 μm. (Equivalent ratio of isocyanate group to hydroxyl group 1:1). Comparative Example 2 Using the same equipment as in Example 1 above, 100 g of bisphenol-based epoxy resin "Epicote 828", 120 g of "Versadime 216", and liquid rubber "Hiker" were added.
CTBN1300×8'' 20g and tetramethylammonium chloride 0.1g were heated to 150℃ with stirring for
After keeping for a while, 14 g of benzoic acid (0.9 mol per equivalent of remaining epoxy group) was added and heated to 170°C while stirring.
After keeping the solution for 5 hours, 169 g of xylene was added to obtain an epoxy-modified polyol resin solution (G) having a hydroxyl value of 148 and containing 60% solids. The subsequent operations were carried out in the same manner as in Example 1, except that 74 g of "Vancenate A-81" was blended as a crosslinking agent, to obtain a cured coating film (ratio 2) with a film thickness of 100 μm (equivalence of isocyanate groups and hydroxyl groups). ratio 1:1). Comparative Example 3 Using the same equipment as in Example 1 above, bisphenol A
100g of epoxy resin “Epicote 828”, 5g of “Versadime 216”, liquid rubber “Hiker”
After keeping 30 g of CTBN1300 After holding for 5 hours, 129 g of xylene was added to obtain an epoxy-modified polyol resin solution (H) having a hydroxyl value of 184 and containing 60% solid content. This product had poor solubility in xylene and was opaque. The following operations are
The process was the same as in Example 1, except that 92 g of "Vancenate A-81" was blended as a crosslinking agent, and a cured coating film (ratio 3) with a film thickness of 100 μm was obtained (equivalent ratio of isocyanate groups to hydroxyl groups 1:1). . Comparative Example 4 Using the same equipment as in Example 1 above, bisphenol A
100g of epoxy resin “Epicote 828”, 20g of “Versadime 216”, liquid rubber “Hiker”
50g of "CTBN1300
After keeping for a while, 52 g of benzoic acid (0.9 mol per equivalent of remaining epoxy group) was added and heated to 170°C while stirring.
After keeping it for 5 hours, 148 g of xylene was added to obtain an epoxy-modified polyol resin solution (I) containing 60% solid content of 162 hydroxyl groups, but it became opaque and had a high viscosity as in Comparative Example 3. Liquidity was lacking. Comparative Example 5 Using the same equipment as in Example 1 above, bisphenol A
100g of epoxy resin "Epicote 1004", 13g of diisopropanolamine (0.5 mole per equivalent of epoxy group), and 0.1g of tetramethylammonium chloride were kept at 170°C for 5 hours with stirring, then 75g of xylene was added. An epoxy modified polyol resin solution (J) with a hydroxyl value of 324 and a solid content of 60% was obtained. The subsequent operations were the same as in Example 1, except that 162 g of "Vancenate A-81" was blended as a crosslinking agent, and a cured coating film with a film thickness of 100 μm (ratio 5)
(equivalent ratio of isocyanate groups to hydroxyl groups 1:1). Comparative Example 6 Bisphenol A was added to the same apparatus as in Example 1 above.
After keeping 100 g of epoxy resin "Epicote 828", 80 g of "Versadime 216" and 0.1 g of tetramethyammonium chloride at 150°C for 5 hours with stirring, 30 g of diisopropanolamine (0.8 mol per equivalent of the remaining epoxy group) ) and maintained at 170° C. for 5 hours with stirring, then 140 g of xylene was added to obtain an epoxy-modified polyol resin solution (K) with a hydroxyl value of 288 and a solid content of 60%. In the subsequent operations, "Vancenate A-81" 144 was used as a crosslinking agent.
The film thickness was adjusted in the same manner as in Example 1 except that g was added.
A cured coating of 100μ (ratio 6) was obtained (equivalent ratio with isocyanate groups 1:1). Comparative Example 7 Using the same equipment as in Example 1 above, bisphenol A
After keeping 100 g of epoxy resin "Epicote 1001", 30 g of liquid rubber "Hiker CTBN 1300 x 8", and 0.1 g of tetramethylammonium chloride at 150°C for 5 hours with stirring, 15 g of diisopropanolamine, (1 remaining epoxy group) 0.5 for equivalent weight
After maintaining the temperature at 170° C. for 5 hours with stirring, 95 g of xylene was added to obtain an epoxy-modified polyol resin solution (L) with a hydroxyl value of 272 and a solid content of 60%. The subsequent operations were the same as in Example 1, except that 136 g of "Vancenate A-81" was blended as a crosslinking agent. Ratio 1:
1). Comparative Example 8 Add the liquid rubber-modified epoxy-modified polyol resin solution (L) obtained in Comparative Example 7 to 50 g of the dimer acid-modified polyol resin solution (K) obtained in Comparative Example 6 above.
50 g was added to obtain a mixed solution containing a solid component with a hydroxyl value of 280. The subsequent operations were the same as in Example 1 except that 140 g of "Vancenate A-81" was added as a crosslinking agent.
In the same manner as above, a cured coating film (8) with a film thickness of 100 μm was obtained. Table 1 shows the results of testing the cured coating films obtained in each Example and Comparative Example. However, all measurement methods were based on JIS K5400 (General Test Methods for Paints). As mentioned above, the epoxy resin composition for coatings of the present invention is excellent in providing satisfactory results in all aspects of flexibility, adhesion, water resistance, corrosion resistance, low temperature curability, and dilutability with organic solvents. Therefore, it should be widely used in the paint industry.

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Claims (1)

[Claims] 1 Bisphenol A with epoxy equivalent of 170 to 1000
100 parts by weight of epoxy resin and 10 to 100 parts of dimer acid
1 mole or less of dialkanolamine or A resin composition for a coating material, in which a polyisocyanate compound is added in an isocyanate group equivalent of 0.7 to 1.3 per equivalent of hydroxyl group of an epoxy modified polyol resin obtained by reacting a monocarboxylic acid.