JPS6210268B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high solids coating composition containing a vinyl-modified polyester resin and an amino resin, which has a high solids content, low viscosity, little repellency of the coating film, and excellent coating performance. In recent years, reducing the amount of solvent in paints has become an important issue in the paint industry due to problems such as oil shock and air pollution. Therefore, as pollution-free and resource-saving measures, water-based paints, solvent-free paints (powder paints, photocurable paints, etc.), and high solid content paints are being developed and considered. However, in the case of high solid content paints, it is difficult to simultaneously satisfy high solid content, low viscosity, and coating film performance. For oil-free alkyd resins, high solids content,
Methods for lowering the viscosity can be roughly divided into (1) using a highly soluble solvent, (2) lowering the degree of condensation through esterification or increasing the excess of hydroxyl groups to lower the molecular weight (3) ) A possible method is to chain the resin structure. However, there is currently no method (1) suitable for use as an industrial solvent. In method (2), very low molecular weight compounds are mixed, the polarity of the resin becomes high, which causes serious defects such as pinhole repellency in the coating film, and the physical properties, boiling water resistance, moisture resistance, etc. are inferior, and it is not good. It is difficult to obtain a coating film. In method (3), since the resin structure is chain-like, network crosslinking is difficult to occur and physical properties are excellent, but boiling water resistance, weather resistance, stain resistance, etc. are poor and it is difficult to obtain a good coating film. The present invention provides a coating composition containing a vinyl-modified polyester resin and an amino resin,
This will solve these problems. That is, the present invention is (A) (a) obtained by reacting a polyhydric alcohol containing 2 to 3 hydroxyl groups in the molecule and a polyhydric carboxylic acid, with a hydroxyl value of 100 to 300 (solid content) and a polymerizable carbon-carbon 95 to 70% by weight of an unsaturated polyester resin having 0.01 to 0.1 double bonds per 100g (solid content) (b) 5 to 30% by weight of an ethylenically unsaturated compound copolymerizable with component (a). and (B) an amino resin. The unsaturated polyester as the component (a) is produced by a known method, and there are no restrictions on its production. For example, by adding a polyhydric alcohol such as neopentyl glycol or trimethylolpropane, a polyhydric carboxylic acid such as isophthalic acid or adipic acid, and if necessary an esterification catalyst such as dibutyltin oxide,
React at 180 to 200℃ for 1 to 2 hours, and then incubate at 180 to 200℃ for 1 to 2 hours.
The temperature was raised to 240°C to carry out the reaction to the end point. The polyhydric alcohol, which is the component (a) above, has 2 in the molecule.
Those containing ~3 hydroxyl groups are used. The use of monoalcohols having only one hydroxyl group in the molecule results in a low molecular weight and poor coating performance. The use of polyhydric alcohols containing four or more hydroxyl groups in the molecule impairs the compatibility when copolymerizing ethylenically unsaturated compounds, causing turbidity of the resin and whitening of the coating film. In addition, the unsaturated polyester resin of component (a) has a hydroxyl value of 100 to 300 (solid content), preferably 150 to 300.
It is necessary to adjust it to 250 (solid content). If the hydroxyl number is less than 100 (solid content), the viscosity of the unsaturated polyester becomes too high, making it difficult to obtain a resin with high solid content and low viscosity, and if it exceeds 300, the molecular weight becomes too small. Furthermore, component (a) contains 0.01 to 0.1, preferably 0.02 to 0.05 polymerizable carbon-carbon double bonds per 100 g (solid content). In order to copolymerize component (a) with an ethylenically unsaturated compound as described below, it is necessary to introduce a polymerizable carbon-carbon double bond into the unsaturated polyester. Raw materials with polymerizable double bonds include fumaric acid, maleic acid,
Dicarboxylic acids such as itaconic acid and saffron oil, dehydrated castor oil, tung oil, which have conjugated double bonds,
There are drying oils or fatty acids such as soybean oil. However, the use of drying oils or their fatty acids is not preferred because they cause deterioration in the adhesion, weather resistance, staining properties, secondary physical properties, etc. of the coating film. In order to make copolymerizability with ethylenically unsaturated compounds more effective, it is more advantageous to introduce double bonds using dicarboxylic acids such as fumaric acid and maleic acid. The amount of raw materials containing these polymerizable double bonds will vary depending on the degree of copolymerization with the ethylenically unsaturated compound described below, but it will prevent resin turbidity and paint film whitening, and will also have a high solid content and low viscosity resin. In order to obtain this, the amount of double bonds must be 0.01 to 0.1 in 100 g (solid content) of the unsaturated polyester resin. i.e. polyester resin
If the amount of double bonds in 100 g (solid content) is less than 0.01, copolymerizability with the ethylenically unsaturated compound will not be sufficient, causing turbidity of the resin and whitening of the coating film. Furthermore, many of the resins obtained are blends of polyester resins and copolymers of ethylenically unsaturated compounds, and coating film performance, especially adhesion, tends to deteriorate due to the difference in curability with amino resins. shows. In addition, as the amount of polymerizable double bonds in unsaturated polyester increases, copolymerizability with ethylenically unsaturated compounds increases, and the turbidity of the resin and whitening of the coating disappear, but on the contrary, the phenomenon of turbidity of the resin and whitening of the coating film disappears. The viscosity becomes extremely high, making it difficult to obtain a resin with high solid content and low viscosity. The amount of polymerizable double bonds in the unsaturated polyester resin must be 0.1 or less. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, neobentyl glycol, 1,6-hexanediol, 1,3-
butanediol, cyclohexanedimethanol,
Trimethylpentanediol, glycerin, trimethylolethane, trimethylolpropane are used. The unsaturated dicarboxylic acids mentioned above include maleic acid,
Fumaric acid, itaconic acid, etc. are used. Examples of the saturated polycarboxylic acids include phthalic anhydride, adipic acid, isophthalic acid, terephthalic acid,
Tetrahydrophthalic anhydride, paratertiary butylbenzoic acid, etc. are used. Next, the copolymerization (vinyl modification) of the unsaturated polyester resin as the component (a) and the ethylenically unsaturated compound as the component (b) will be explained. The weight ratio of components (a) and (b) is (a)/(b)=95/5~
The reaction is carried out at a ratio of 70/30, preferably 90/10 to 80/20. If it exceeds 95/5, there will be no effect of improving the repellency, boiling water resistance, and moisture resistance of the coating film due to vinyl modification, and if it is less than 70/30, the viscosity of the resin will become too high.
It is difficult to obtain resins with high solid content and low viscosity. The reaction between component (a) and component (b) is carried out using benzoyl peroxide, azobisisobutylnitrile, t
-Butyl peroxybenzoate, N-nitrosoacrylanilide, p-bromobenzenediazo hydroxide, triphenylmethylazobenzene, etc. Polymerization catalysts that are relatively difficult to copolymerize and have a low decomposition temperature, such as azobisisobutylnitrile, tend to form polymers of ethylenically unsaturated compounds. Preferably, it is used in combination with a catalyst. Examples of the ethylenically unsaturated compounds include styrene, α-chlorostyrene, vinyltoluene, paratertiary butylstyrene, methyl acrylate,
Ethylenically unsaturated compounds without carboxyl or hydroxyl groups such as isobutyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, α-hydroxyethyl acrylate, methacrylic acid β-hydroxyethyl, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, acrylic acid,
Ethylenically unsaturated compounds containing carboxyl or hydroxyl groups such as methacrylic acid are used, but ethylenically unsaturated compounds other than styrene are relatively difficult to copolymerize with unsaturated polyesters using maleic acid or fumaric acid. Therefore, it is preferable to use it in combination with styrene. In addition, there are ethylenically unsaturated compounds having a glycidyl group such as glycidyl methacrylate, but care must be taken when using these as they tend to increase the viscosity of the resin. By adjusting the type and amount of the ethylenically unsaturated compound used, the performance of the coating film can be appropriately adjusted to the intended purpose. In other words, if the unsaturated polyester resin has a high molecular weight (viscosity) and has a side chain structure, the amount of ethylenically unsaturated compound used should be reduced, and ethyl acrylate,
Using linear raw materials such as butyl methacrylate, 2-ethylhexyl methacrylate, and butyl acrylate to reduce the molecular weight of a copolymer of ethylenically unsaturated compounds by adjusting the polymerization catalyst and synthesis method. This allows the coating film performance to be balanced. In addition, the use of ethylenically unsaturated compounds containing carboxyl or hydroxyl groups tends to increase the viscosity of the resin, and the amount of functional groups (carboxyl and hydroxyl groups) in the unsaturated polyester resin
It is preferable to use them together when there is a small amount of If the odor of unreacted ethylenically unsaturated compounds becomes a problem, it can be improved by removing the solvent while raising the temperature to 200 to 240° C. after the copolymerization reaction and recovering unreacted monomers at the same time. The vinyl-modified polyester resin obtained as described above is used in combination with a curing agent such as an amino resin. Amino resin cures at industrial baking temperatures of 120 to 180°C and provides a good coating. Amino resin is 90-70% by weight of vinyl modified polyester resin
10 to 30% by weight is practical, but the amount added varies depending on the application. If it is less than 10% by weight, the crosslinking reaction will not be sufficient and the coating performance will deteriorate overall. If the amount used exceeds 30% by weight, the amino resin tends to undergo a self-crosslinking reaction, and the resulting coating film will be hard and brittle, and its chemical properties will be significantly inferior. The amino resin can be obtained by adding an aldehyde such as formalin or paraformaldehyde to an amino compound such as urea, melamine, benzoguanamine, or spiroguanamine, and then etherifying the reaction with a monoalcohol having 1 to 4 carbon atoms. Industrially n
- Mainly butanol-modified amino resins, isobutanol-modified amino resins, and methanol-modified amino resins. Methanol-modified amino resin, i.e., methylated melamine resin, has higher solid content and lower viscosity than normal-butanol and isobutanol-modified amino resins, and also has higher crosslinking density, so it has better weather resistance. It has excellent stain resistance, hardness, etc. Industrially, the resin concentration is 70% by weight.
The above are the main points, and by combining with the vinyl-modified polyester resin of the present invention, a paint with a high solid content can be obtained, and the physical properties, boiling water resistance, moisture resistance, stain resistance,
A coating film with excellent weather resistance can be obtained. Furthermore, if it is necessary to promote the crosslinking reaction of the methylated melamine resin, 3 to 0.5% by weight of sulfonic acid or a salt of sulfonic acid and amines can be added.
Hardness, stain resistance, etc. can be improved. Furthermore, depending on the application, for example, an epoxy resin such as Epicoat 1001 (manufactured by Shell Chemical Co., Ltd.) can be added to improve adhesion, moisture resistance, etc., and coating film performance can be adjusted as appropriate. Cymel is the methylated melamine resin mentioned above.
300, 301 (manufactured by American Cyanamid), Nikaratsuku MX40 (manufactured by Sanwa Chemical), Sumimaru M-
Commercially available products such as 40S and 30S (manufactured by Sumitomo Chemical) can be used. As the diluting solvent, aromatic compounds such as triol and xylol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, ethers such as butyl cellosolve and ethyl cellosolve, and esters such as butyl acetate and cellosolve acetate are used.
In order to achieve a solvent composition that has as low a viscosity as possible and a high solids content that poses no problems during painting operations, the concentration of the resin must be adjusted.
It is preferable to use a solvent or mixed solvent that has a viscosity of 150 poise (25° C.) or less at 80±1% by weight. For example, a mixed solvent such as xylol/methyl isobutyl ketone=1/1 (weight ratio) or butyl cellosolve/methyl isobutyl ketone=1/1 (weight ratio) can be used. Next, examples will be shown. Hereinafter, "part" means "part by weight" and "%" means "% by weight." Example 1 310 parts of neopentyl glycol, 115 parts of trimethylolethane, and 208 parts of isophthalic acid were placed in a four-necked flask, and heated to 180 parts while passing inert gas.
℃ for 2 hours, and then at 200℃, acid value 35.6 (solid content)
215 parts of adipic acid and 20 parts of maleic anhydride were added and the esterification reaction was continued at 180°C for 2 hours and then at 220°C until the solid content was 80±1% with xylol. Adjust to
The end point was when the viscosity reached 22.7 to 34 poise (25°C). After the reaction was completed, about 150 parts of xylene was added to adjust the solid content to 80±1%. The resulting resin had a solid content of 80.1%, a viscosity of 28 poise, an acid value of 8.9, a hydroxyl value of 226, and a double bond of 0.07 per 100 g of resin. The above unsaturated polyester resin adjusted to xylol solid content of 80% was placed in another four-necked flask.
A mixed solution of 32 parts of styrene, 28.8 parts of butyl methacrylate, 1.3 parts of β-hydroxyethyl methacrylate, and 1.9 parts of t-butyl peroxybenzoate was heated to 150°C and placed in a separating funnel for 1 hour. After the drop was finished, the temperature was kept at the same temperature for 4 hours, and the temperature was raised to 200℃ while
80 parts were collected, cooled to below 100°C, and 80 parts of methyl isobutyl ketone was added to adjust the solid content to 80%. The resulting resin had a solid content of 79.5%, a viscosity of 63.4 poise (25°C), and an acid value of 8.1. Example 2 262 parts of neopentyl glycol, 113 parts of trimethylolpropane, 74 parts of 1,6-hexanediol
and 209 parts of isophthalic acid were charged into two four-necked flasks, and the esterification reaction was proceeded in the same manner as in Example 1. The acid value was 40 (solid content) and the mixture was cooled to 100°C. Added a section. Further, the esterification reaction was carried out in the same manner as in Example 1, and the solid content was adjusted to 80 ± 1% with xylene, and the viscosity was 18 to 20%.
The end point was the point at which the temperature reached poise (25°C). After the reaction, approximately 194 parts of xylene was added to bring the solid content to 80±1%.
Adjusted to. The resulting resin has a solid content of 80.8% and a viscosity of
24 poise (25℃), acid value 5.6, hydroxyl value 224
The number of double bonds in 100g of resin was 0.08. 680 parts of the above unsaturated polyester resin adjusted to a solid content of 80 ± 1% with xylol was placed in another four-necked flask, heated to 160°C, and placed in a separating funnel with 33 parts of styrene and 38 parts of butyl methacrylate. 10 parts of ethyl acrylate, 2 parts of β-hydroxyethyl methacrylate, and 4 parts of t-butylperoxybenzoate were uniformly added dropwise over 1 hour, and kept at the same temperature for 4 hours after the addition was completed. 90 parts of xylene was collected while keeping the temperature up to 200°C, cooled to below 100°C, and 90 parts of methyl isobutyl ketone was added to adjust the solid content to 80±1%. The resulting resin had a solid content of 80.1%, a viscosity of 76 poise (at 25°C), and an acid value of 4.7. Example 3 369 parts of neopentyl glycol, 95 parts of trimethylolethane, and 196 parts of isophthalic acid were charged into a four-necked flask, and the esterification reaction was proceeded in the same manner as in Example 1. After reaching an acid value of 28 (solid content), The mixture was cooled to 100°C, and 173 parts of adipic acid and 38 parts of maleic acid were added. Further, the esterification reaction was carried out in the same manner as in Example 1, and the end point was the point at which the viscosity reached 7 to 15 poise (25°C) when the solid content was adjusted to 80±1% with xylene. After the reaction was completed, about 195 parts of xylene was added to adjust the solid content to 80±1%. The number of double bonds in 100 g of resin was 0.1. The resulting resin has a solid content of 80.5
%, viscosity 11 poise (25°C), acid value 7.8, and hydroxyl value 283. The above unsaturated polyester resin adjusted to a solid content of 80 ± 1% with xylol was placed in another 14-neck flask, heated to 160°C, and placed in a separating funnel. Styrene 54 parts and butyl methacrylate 54 parts. ,t
- A mixture of 8 parts of butyl peroxybenzoate was uniformly dropped over 1 hour, and after the dropwise addition was completed, it was heated to 4 parts at the same temperature.
After incubating for an hour, xylol was heated to 200°C while
A portion was collected and cooled. At 100°C or lower, 82 parts of methyl isobutyl ketone was added to adjust the solid content to 80±1%. The resulting resin had a solid content of 79.8%, a viscosity of 61 poise (at 25°C), and an acid value of 6.2. Comparative Example 1 308 parts of neopentyl glycol, 59 parts of trimethylol ethane, 50 parts of pentaerythol, and 246 parts of isophthalic acid were placed in a four-necked flask, and the esterification reaction was proceeded in the same manner as in Example 1 until the acid value reached 58. Once reached, it was cooled to 100°C and 216 parts of adipic acid were added. Further, the esterification reaction was carried out in the same manner as in Example 1, and the end point was when the viscosity reached 30 to 60 poise (25°C) when the solid content was adjusted to 80±1% with xylene. After the reaction was completed, about 200 parts of xylene was added to adjust the solid content to 80±1%. The resulting resin had a solid content of 80.1%, a viscosity of 51 poise (at 25°C), an acid value of 9.8, a hydroxyl value of 218, and 0 double bonds in 100 g of the resin. Comparative Example 2 720 parts of the resin of Comparative Example 1 adjusted to 80±1% with xylol, 30 parts of maleic anhydride, 7.5 parts of xylol
The mixture was heated to 150°C and reacted for 1 hour. Furthermore, a mixture of 32 parts of styrene, 28.8 parts of butyl methacrylate, 1.3 parts of β-hydroxyethyl methacrylate, and 1.9 parts of t-butylperoxybenzoate in a separating funnel was uniformly added dropwise over 1 hour.
After the completion of the dropwise addition, the mixture was kept at the same temperature for 4 hours, and 68 parts of xylene was recovered while raising the temperature to 200°C. After completion of recovery, the mixture was cooled to below 100°C, and about 204 parts of methyl isobutyl ketone was added to adjust the concentration to 70±1%. The obtained resin was cloudy and did not change even after removing solvents such as xylene and methyl isobutyl ketone, and whitening of the coating film was observed. Next, an application example will be shown in which the resin of the example is made into a paint. Application Example 1 Table 1 shows an example of application to the top coat of household electrical appliances.

【table】

【table】

【table】 Application example 2 Table 2 shows examples of applications for automotive interior coatings.

[Table] As is clear from the above, the coating composition containing the vinyl-modified polyester resin and amino resin according to the present invention has a high solids content, and has little repellency of the coating film, which is an important workability characteristic. membrane performance,
In particular, the physical properties, boiling water resistance, and moisture resistance can be significantly improved compared to conventional coating compositions using high solid content polyester resins. The coating composition according to the invention has a high solids content,
Therefore, it is possible to provide a coating composition that can contribute to resource saving and pollution control, and has a low viscosity, which has great practical effects in terms of efficiency of coating work and coating film performance.

Claims (1)

[Claims] 1 (A) (a) A polyhydric alcohol containing 2 to 3 hydroxyl groups in the molecule and a polyhydric carboxylic acid, which have a hydroxyl value of 100 to 300 (solid content), and a polymerization 100 carbon-carbon double bonds
95 to 70% by weight of an unsaturated polyester resin having 0.01 to 0.1 particles in g (solid content) (b) Vinyl obtained by reacting 30 to 5% by weight of an ethylenically unsaturated compound copolymerizable with component (a) A high solid content coating composition comprising a modified polyester resin and (B) an amino resin. 2. The high solid content coating composition according to claim 1, comprising 70 to 90% by weight of a vinyl-modified polyester resin and 30 to 10% by weight of an amino resin. 3. The high solid content coating composition according to claim 1 or 2, wherein the amino resin is a methyl etherified amino resin etherified with methanol.