JPS6215588B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high solids coating composition comprising a mixture of an acrylic resin and a non-aqueous dispersion resin composition. Recently, in the field of paints as well, there has been a demand for measures to reduce pollution and save resources in response to regulations on the use of solvents due to worsening air pollution and in consideration of the waste of resources. One of the measures that can solve these problems at the same time is the development of a so-called high solid content type coating composition in which the solvent content in the paint is reduced and the solid content is increased in concentration. In view of the above circumstances, the inventors previously
Number average molecular weight 1000-8000, glass transition point -20
We have developed a thermosetting high solids coating composition consisting of a mixture of a thermosetting acrylic resin at ~20°C and a nonaqueous dispersion type thermosetting resin, an amino resin, and an organic solvent, and have applied for a patent. Unexamined Japanese Patent Publication 1972-
No. 35220). The present inventors conducted further studies on such coating compositions and found that the coating compositions were inferior in terms of physical performance and durability (gloss retention, occurrence of cracking), etc. Such defects may occur when applied to automobiles, household appliances, industrial equipment, steel furniture, non-metals, etc.
This is important and improvements are required. As a result of intensive research aimed at eliminating such defects, the inventors of the present invention have developed an acrylic material having a specific number average molecular weight, a specific lower glass transition temperature, and a specific hydroxyl value, which are larger than those in the previous invention. The present invention was completed based on the discovery that the object can be achieved by using the resin in combination with a non-aqueous dispersion type resin composition. That is, the present invention provides ()(a) an acrylic ester having an alkyl group having 1 to 12 carbon atoms, a methacrylic ester having an alkyl group having 1 to 12 carbon atoms, and a mixture thereof; At least one of them is obtained by polymerizing or copolymerizing an acrylic monomer having a hydroxy group.
Glass transition temperature -25℃ to -60℃, hydroxyl value 60
20 to 95% by weight (solids) of an acrylic resin having a number average molecular weight of 10,000 to 30,000 and (b) a nonaqueous dispersion type resin composition of 80 to 5
% by weight (resin solid content) and () an amino formaldehyde resin etherified with a monohydric alcohol having 1 to 4 carbon atoms as essential components, the content of which is as follows:
A high solid content type characterized by a solid content of 50 to 90 parts by weight of component () and 50 to 10 parts by weight of component () for a total of 100 parts by weight of component () and component (). It is a coating composition. The high solids coating composition of the present invention is particularly distinctive in that it contains the specific acrylic resin described in () (a) above. The coating composition of the present invention is a curable resin composition that forms a cured film by three-dimensionalization based on the reaction between component ()(a) and/or ()(b) and component (). It is a thing. The acrylic monomers used in the acrylic resin of component () (a) in the present invention, that is, methacrylic esters having an alkyl group having 1 to 12 carbon atoms and acrylic esters having an alkyl group having 1 to 12 carbon atoms, include, for example, Methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Examples include 2-hydroxyethyl, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, equimolar reaction products of acrylic acid or methacrylic acid and dihydric alcohol having 8 or less carbon atoms, glycidyl acrylate, glycidyl methacrylate, etc. . The acrylic monomer as exemplified above has 50
Amounts ranging up to 35% by weight can be replaced by other polymerizable ethylenically unsaturated monomers. Examples of these polymerizable ethylenically unsaturated monomers include styrene, acrylamide, acrylic acid, methacrylic acid, vinyltoluene, and the like. The acrylic resin of component () (a) in the present invention uses the above monomer, has a glass transition temperature of -25 to -60°C, preferably -35 to -55°C, and a hydroxyl value of 60 to 200, preferably 80-160, and the number average molecular weight is 10,000-30,000, preferably 10,000-
25,000, and at least one of the acrylic monomers used should have a hydroxyl group. In the present invention, when the number of carbon atoms in the alkyl group of the acrylic monomer used in the acrylic resin of component () (a), that is, the esters of acrylic acid and methacrylic acid, exceeds 12, the weather resistance of the polymer and coating film decreases. . In addition, when a part of the acrylic monomer is replaced with another polymerizable ethylenically unsaturated monomer, the proportion thereof is 50% by weight in the acrylic resin.
A larger amount is not preferable because the glass transition temperature increases and the durability of the coating film deteriorates. In addition, the glass transition temperature of acrylic resin is -20℃
If the temperature is higher than this, the resin viscosity becomes high and it becomes difficult to obtain a high degree of solidification. On the other hand, if the temperature is lower than -60°C, the hardness of the coating film becomes insufficient, which is not preferable. Furthermore, if the hydroxyl value is less than 60, the curability, physical performance, durability, etc. of the coating film will be poor, and if it is greater than 200, the flexibility of the coating film will be reduced. Furthermore, if the number average molecular weight is less than 10,000, there will be difficulties in physical strength, durability, hardness, etc., especially if it is cured at low temperatures, and if it is greater than 30,000, the glass transition temperature will be -25 to -60℃. Also, high solid differentiation is difficult. The glass transition temperature of acrylic resin is determined by the empirical formula 1/Tg=W(a ₁ )/Tg(a ₁ ) +W(a ₂ )/Tg(a ₂ )...+W(an)/Tg
(an) (In the above formula, Tg is the glass transition temperature of the acrylic resin expressed in absolute temperature, W (a ₁ ), W (a ₂ )...W
(an), etc. are the weight fractions of component monomers a ₁ , a ₂ ...an, etc. in the acrylic resin, Tg (a ₁ ), Tg
(a ₂ ), . . . Tg(an), etc. are calculated and determined from the glass transition temperature expressed in absolute temperature of the homopolymer of each of the component monomers. Hydroxyl value is JISK1557
-1970 6.4, and the hydroxyl value can be adjusted by adjusting the amount of the hydroxyl group-containing monomer used. Polymerization or copolymerization reactions in the production of acrylic resins can be carried out by known methods. The nonaqueous dispersion type resin composition of component () (b) in the composition is known per se, and is prepared by dispersing or dispersing a polymeric dispersion stabilizer in an organic solvent, which is partially or completely dissolved in the organic solvent. is formed by polymerizing monomers that dissolve in the organic solvent as monomers but not as polymers, and the polymer of the monomers is used as a film-forming polymer component (particle core component). ). In the present invention, all known non-aqueous dispersion type resin compositions defined above can be used. As the film-forming polymer component of the non-aqueous dispersion type resin composition of component () (b) used in the present invention, acrylic polymers are preferred, such as methyl methacrylate, ethyl methacrylate,
Methacrylate esters such as n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, stearyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, methyl acrylate, Ethyl acrylate, n-butyl acrylate,
Acrylic acid esters such as isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl acrylate, and hydroxypropyl acrylate, α/β-ethylenically unsaturated acids such as acrylic acid and methacrylic acid, n - Polymers or copolymers made from monomers such as acrylamides such as butoxymethylacrylamide, N-methylolacrylamide and acrylamide, and methacrylamides such as n-butoxymethylmethacrylamide, N-methylolmethacrylamide and methacrylamide. used. Further, polymers or copolymers of styrene, vinyltoluene, acrylonitrile, methacrylonitrile, vinyl acetate, vinylpyridine, vinylpyrrolidone, etc. can also be used. In addition, examples of dispersion stabilizers (particle shell components) used in the production of non-aqueous dispersion type resin compositions include the following polymer compounds (however, they are partially or completely soluble in the organic solvent used). . (1) Addition reaction product of a self-condensed polyester of a fatty acid containing a hydroxyl group such as 12-hydroxystearic acid with glycidyl acrylate or glycidyl methacrylate and the same method used to obtain the film-forming polymer. A graft polymer obtained by copolymerizing acrylic ester or methacrylic ester. (2) Octyl acrylate, lauryl acrylate,
After copolymerizing a long chain alkyl ester of acrylic acid or methacrylic acid such as stearyl acrylate, octyl methacrylate, lauryl methacrylate or stearyl methacrylate with acrylic acid or methacrylic acid and optionally other vinyl monomers, The same type of acrylic monomer used to obtain the film-forming polymer is added to the polymer having side chain double bonds obtained by reacting the carboxyl groups of the copolymer with glycidyl acrylate or glycidyl methacrylate. A graft polymer obtained by copolymerization. (3) A copolymer whose main component is an ethylenically unsaturated monomer such as a long-chain alkyl ester of acrylic acid or methacrylic acid, and where necessary other ethylenically unsaturated monomers are copolymerized. (4) Alkylated melamine polymer (melamine core is 10
more than the nucleus). (5) A graft polymer obtained by graft polymerizing polybutadiene, polyisoprene, etc. with the same type of acrylic monomer used to obtain the film-forming polymer. (6) Alkyd resin. Note that the dispersion stabilizers (1) to (6) can also be used in combination as necessary. A non-aqueous dispersion type resin composition can be produced by polymerizing a film-forming polymer component in an organic liquid in the presence of a dispersion stabilizer synthesized in advance, or by polymerizing a film-forming polymer component in an organic solvent. It can be produced by polymerizing the dispersion stabilizer simultaneously with the polymerization of the polymer component. Generally, polymerization is preferably carried out by dissolving a dispersion stabilizer in an organic liquid and then dropping the monomer solution and polymerization initiator used in obtaining the film-forming polymer into this solution. At this time, by appropriately selecting the synthesis conditions, the solid content concentration and viscosity can be freely changed. For example, even at a high solid content concentration of 50 to 70%, a low viscosity dispersion can be produced It can be synthesized extremely easily. The polymer component and dispersion stabilizer in the nonaqueous dispersion type resin composition preferably contain a functional group that reacts with the amino resin, such as a hydroxyl group or a carboxyl group. The amount of dispersion stabilizer used is 95 to 95% of the film-forming polymer component.
Usually 5 to 40% by weight compared to 60% by weight (solid content)
(solid content). 80% by weight non-aqueous dispersion type resin composition
(Solid content) If a larger amount is used, reductions in the gloss of the coating film, poor smoothness of the coating surface, reduction in toughness and softness of the coating film, and reduction in pigment stability are likely to occur, making it impractical. Furthermore, if the non-aqueous dispersion resin composition is less than 5% by weight (solid content), the coating film tends to sag, and the curability and durability of the coating film decreases, which is not preferable. Examples of the amino in the etherified amino formaldehyde resin component () in the high solids coating composition of the present invention include melamine, urea, benzoguanamine, acetoguanamine, stearoguanamine, and spiroguanamine. amino·
The alcohol used for etherification of formaldehyde resin has the chemical formula ROH.
Examples of R include monohydric alcohols having 1 to 4 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, and isobutyl. Such etherified amino-formaldehyde resins contain 1 to 3
Nuclear bodies are preferred, and those in which at least 30%, preferably at least 50%, (particularly preferably at least 65%) of the methylol groups are etherified are preferred. Component () in the high solids coating composition of the present invention contains the acrylic resin as component () (a) and the non-aqueous dispersion resin composition as component () (b) described above. It is a mixture that The content ratio of component () (a) and component () (b) in component () is the solid content ratio.
For the total of 100% by weight of (a) and components () and (b), component () (a) is 20 to 95% by weight, and component () (b) is 80 to 5% by weight.
Weight%. Needless to say, the content of the above components () and (b), ie, the non-aqueous dispersion type resin composition, includes the amount of the film-forming polymer component and the amount of the dispersion stabilizer component. Component () in the coating composition of the present invention, that is, a mixed system of () (a) acrylic resin and () (b) non-aqueous dispersion type resin composition and component () etherified amino formaldehyde resin. The content ratio of component () and component () is the solid content ratio.
For a total of 100 parts by weight, component () is 50 to 90 parts by weight, and component () is 50 to 10 parts by weight. If the amount of the etherified amino formaldehyde resin is more than 50 parts by weight or less than 10 parts by weight, curing suitable for coating performance will not be achieved, which is unfavorable in terms of hardness, physical properties, chemical resistance, durability, etc. The high solids coating composition of the present invention may further contain a known acid catalyst as a catalyst for the curing reaction of the amino-formaldehyde resin with the hydroxy group-containing acrylic resin, if necessary. Examples of acid catalysts include hydrochloric acid, phosphoric acid, dimethyl phosphate, triethyl phosphate, tricresyl phosphate,
Triphenyl phosphate, tributyl phosphate, trimethyl phosphate, xylene sulfonic acid, toluenesulfonic acid, sulfanilic acid, sulfobenzoic acid, naphthalene sulfonic acid, benzenesulfonic acid, sulfosalcylic acid, methanesulfonic acid, ethanesulfonic acid, aminophenolsulfonic acid , aminobenzenesulfonic acid, etc. The amount of the acid catalyst added is preferably in the range of 0.1 to 6.0 parts by weight, and preferably 0.5 to 6.0 parts by weight, based on 100 parts by weight of the mixed resin solid content of the acrylic resin/nonaqueous dispersion type resin composition and the etherified amino formaldehyde resin.
A range of 3.0 parts by weight is more preferred. Each component of the high solids coating composition of the present invention is:
Usually, the composition of the present invention, which is composed of these components, contains the organic solvent used in the manufacturing step. however,
By using each component that does not contain an organic solvent, a composition that does not contain an organic solvent can be made into a powder coating. Moreover, in addition to the organic solvent based on each component, an organic solvent can also be added to the composition of the present invention. The organic solvent added separately may be the same as or different from the organic solvent based on each component. The content of the organic solvent is preferably such that the total solid content of the composition is 50% or more, preferably 55 to 80% by weight. Examples of organic solvents that can be used include hydrocarbon solvents such as heptane, toluene, and xylene; alcohol solvents such as propyl alcohol and butanol;
Ester solvents such as ethyl acetate and butyl acetate,
Ketone solvents such as acetone and methyl ethyl ketone, other ethers, alcohol ethers,
These include organic solvents such as alcohol esters and ether esters, and there are no particular restrictions on the type of solvent. The high solids coating composition of the present invention may contain inorganic or organic colored pigments, metal powder such as aluminum flakes, and fillers, if necessary. Further, for coating, a normal air spray, airless spray, electrostatic coating, roll coater, curtain flow coater, etc. may be used. Furthermore, it is of course possible to apply the paint by heating it (30 to 60°C) using a hot spray method, and in this case, it becomes possible to handle the paint at even higher solids. The baking temperature of the paint coating ranges from room temperature to 200°C, and is usually cured at 50°C to 180°C. Particularly in curing at low temperatures below 100°C, the combination of an acid catalyst is effective. The resulting coating is a composition with high utility value as an industrial material, which is strong and has excellent hardness, resistance to tolerable agents, non-adhesiveness, durability, and durability. Hereinafter, the present invention will be described in more detail with reference to Examples, but those skilled in the art will be able to make a wide range of modifications without departing from the gist of the present invention. It's not something you receive. In addition, parts and % in manufacturing examples and examples are parts by weight and % by weight unless otherwise specified. (A) Production example of acrylic resin varnish Production example A-1 Put 56.3 parts of butyl acetate into a 300ml four-necked flask equipped with a thermometer, stirrer, condenser, and dropping funnel, and replace the air in the flask with nitrogen. After replacing, keep the contents below 30°C and add 2.0 parts of azobisisobutyronitrile, 60.0 parts of orthobutyl acrylate,
A monomer mixture consisting of 30.0 parts of 2-hydroxyethyl acrylate and 10.0 parts of styrene was placed in a dropping funnel, and the contents of the flask were kept at 120°C and added dropwise over 3 hours. After dropping, keep at this temperature for 1 hour, then add 0.5 azobisdimethylvaleronitrile.
A mixture of 1.5 parts and 10 parts of butyl acetate was added dropwise over 1.5 hours, and the mixture was then reacted at 120°C for 2 hours. Polymerization rate 100%, number average molecular weight approximately 18500, solid content approximately
Viscosity N at 60% (Gardner viscometer/25℃ or less), hydroxyl value 145, glass transition temperature -48℃,
A varnish containing 60% by weight of acrylic resin was obtained. Production Examples A-2 to A-12 Acrylic resins were produced in the same manner as Production Example A-1 based on the monomer formulations shown in Table-1.

【table】

[Table] (B) Example of manufacturing a non-aqueous dispersion Manufacturing example B-1 15 parts of melamine, 54 parts of butyl formaldehyde solution (40%), 3 parts of butyl alcohol, and 0.03 part of phthalic anhydride were heated for 5 minutes and refluxed. let
Then 23 parts of lauryl alcohol and 5 parts of xylene were added and the mixture was heated for 8 hours to remove water. Gardner viscosity (25℃) is Z (70%)
The ratio of formaldehyde to melamine in the product was about 5-6:1. above product
176 parts were dissolved in a mixture of 343.5 parts of mineral spirits, 86 parts of n-octane, and 1.3 parts of benzoyl peroxide. The mixture was heated to 80° C. with stirring under nitrogen atmosphere. Thereafter, the following monomer mixture was added dropwise over 5.5 hours. Acrylonitrile 77.5 Methyl methacrylate 147.5 N-Butyl methacrylate 116 2-Hydroxyethyl methacrylate 46 Benzoyl peroxide 5.2 The temperature was maintained at 80° C. throughout the above dropwise addition period to form the dispersion. After dropping, keep the temperature for 1 hour.
It was kept at 80℃. The reaction product was a milky white dispersant with a low viscosity and a resin content of 50%. The resin content was concentrated to 60% under reduced pressure. Production Example B-2 190 parts of butyl alcohol was heated to 118°C and refluxed. After that, 90 parts of methyl methacrylate, 360 parts of 2-ethylhexyl acrylate, 2 parts of methacrylic acid,
-150 parts of hydroxypropyl and 9 parts of azobisisobutyronitrile were added over a period of 3 hours, during which time refluxing was continued. One hour after the addition was complete, a mixture of 10 parts of butyl alcohol and 3 parts of azobisdimethylvaleronitrile was added and the mixture was stirred at reflux for an additional 3 hours. Add 200 parts of the above product to 387 parts of ethylcyclohexane
It was distributed to different departments. The mixture was heated to reflux.
The following monomer mixture was then added over a period of 4 hours. Methyl acrylate 52.5 n-butyl methacrylate 80.5 Acrylonitrile 57.5 Methyl methacrylate 105 Hydroxyethyl acrylate 52.5 Acrylic acid 2 Aliphatic naphtha 50 t-Butyl peroxyoctoate 3.5 Reflux continued throughout the above addition times to form a dispersion. Ta. After the addition was completed, the mixture was refluxed and stirred for 1 hour. The reaction product was a milky white dispersion with a resin solids content of 46.9%. The solvent was distilled off under reduced pressure to reduce the resin content to 60%. Production Example B-3 (a) A mixture of 540 parts of 12-hydroxystearic acid and 60 parts of xylene was heated to reflux in a nitrogen atmosphere, and about 25 parts of water was removed by azeotropy. The non-volatile content in the solution is 90%, and the molecular weight of the obtained poly-12-hydroxystearic acid is approximately
It was 1500. 560 parts of this solution of poly-12-hydroxystearic acid was diluted with 44.0 parts of xylene, and 0.5 part of hydroquinone and 1 part of N・N'-dimethyldodecylamine were added to the solution, and together with 60 parts of glycidyl methacrylate, the acid value was reduced to 1 or less. Refluxing was continued until the (b) While refluxing a mixture of 180 parts of ethyl acetate and 90 parts of butyl acetate, the following monomers were added over a period of 3 hours. Solution obtained in (a) 500 parts Methyl methacrylate 200 parts Ethyl acrylate 50 parts Azobisisobutyronitrile 10 parts After the addition was complete, refluxing was continued for another 2 hours. The concentration of the graft polymer in the resulting solution was 49%. (c) 8 parts of mineral spirits, 1.4 parts of the graft polymer solution obtained in (b), 4.5 parts of methyl methacrylate
1 part, 0.01 part of n-octyl mercaptan, and 0.2 part of azobisisobutyronitrile were heated under reflux at 75°C for 1 hour. The following monomers were added to it for about 4 hours. Methyl methacrylate 79 parts Methacrylic acid 1 part 2-hydroxyethyl acrylate 20 parts Azobisisobutyronitrile 1.35 parts At the same time, 9 parts of the graft polymer solution obtained in (B) was dissolved in 5 parts of mineral spirits. Solutions were added during the first 2 hours. The reaction was further carried out at 75°C for 2 hours. The reaction product had a resin solids content of 54%. The solvent was distilled off from this under reduced pressure, resulting in a resin content of 60%. (C) Production example of amino formaldehyde resin Production example C-1 Add 126 parts of melamine, 525 parts of isobutanol formalin (formaldehyde concentration 40%), 625 parts of isobutanol, and 56 parts of pure water to a reaction tank, and heat under reflux for 3 hours. After dehydration, excess isobutanol was replaced with xylene to obtain an aminoformaldehyde resin. The resulting solution had a solids content of 80% and a Gardner-Holtz viscosity of P. Production example C-2 126 parts of melamine, 250 parts of n-butyl alcohol,
Add 520 parts of n-butanol formalin (formaldehyde concentration 40%) and 0.01 part of phthalic anhydride,
The mixture was dehydrated under heating under reflux for a period of time, and excess n-butanol was replaced with xylene to obtain an aminoformaldehyde resin. The resulting solution had a solids content of 70% and an Odnerholtz viscosity of E. Example 1 To 35 parts of the acrylic resin of Production Example A-1, 125 parts of titanium oxide (R-500 manufactured by Teikoku Kako Co., Ltd.), 8 parts of methyl ethyl ketone, 10 parts of xylene, and 1 part of a dispersant (manufactured by Raybow Chemical Co., Ltd., Raybow #3) were added. Pebble Mill at 10
Disperse to a micron size, immediately add 11 parts of the above acrylic resin, and operate a pebble mill for about 30 minutes for stabilization. Then, 36 parts of the above acrylic resin,
84 parts of non-aqueous dispersion of Production Example B-1, 10 parts of methyl ethyl ketone, 2 parts of xylene, Production Example C-
32 parts of amino formaldehyde resin No. 1 was uniformly mixed into the Pebble Mill base with stirring to obtain a coating composition. Furthermore, add 4 parts of para-toluenesulfonic acid,
Mixed uniformly with a stirrer. The obtained coating composition was applied to a polished mild steel plate (300
x 90 x 0.8 mm) to a film thickness of 35 to 45 microns (solid content at the time of coating: 75%), left indoors for about 15 minutes, and cured under the conditions shown in Table 4. did. The test results are shown in Table-4. Examples 2 to 10 and Comparative Examples 1 to 6 Coating compositions were prepared in the same manner as in Example 1 with the formulations shown in Tables 2 and 3, and coated on test plates in the same manner as in Example 1. Performance tests were conducted. The results are shown in Table-4.

【table】

【table】

【table】

【table】

[Table] The test method is as follows. (1) Gloss: 60 degree specular reflectance was examined. (2) Pencil hardness: A scratch test was conducted with a pencil. (3) Gasoline resistance: Tested by applying regular type gasoline to a rag and wiping it 20 times. (4) Toluene resistance: Tested by pour-coating toluene. (5) Water resistance: Soaked in water at 20°C for 4 days. (6) Accelerated weathering: Irradiated for 500 hours with a weather meter. (7) Gel fraction: Indicates the acetone elution residue. (8) Yellowing resistance: L, a, after irradiation with germicidal lamp for 24 hours.
b, was measured and ΔE was calculated. (9) Gloss retention rate: Ratio of gloss to initial gloss after 500 hours of main irradiation using a Weathero meter. (10) Impact test: Dupont impact tester, 500g,
Results at 1/2 inch 50cm. ○ indicates no abnormality, × indicates cracking or peeling of the paint film.

Claims (1)

[Scope of Claims] 1 ()(a) An acrylic ester having an alkyl group having 1 to 12 carbon atoms, a methacrylic ester having an alkyl group having 1 to 12 carbon atoms, and a mixture thereof. At least one of them is obtained by polymerizing or copolymerizing an acrylic monomer having a hydroxyl group, and has a glass transition temperature of -25°C to -60°C, a hydroxyl value of 60 to 200, and a number average molecular weight of 10,000 to 10,000.
Acrylic resin with 30000 20-95% by weight
(solid content) and (b) non-aqueous dispersion type resin composition 80-5
% by weight (resin solid content), () an amino formaldehyde resin etherified with a monohydric alcohol having 1 to 4 carbon atoms, and () an acid catalyst as essential components, the content of which is as follows: In terms of solid content, for a total of 100 parts by weight of component () and component (), component () is 50 to 90 parts by weight, component () is 50 to 10 parts by weight, and component () is 0.1 to 0.1 parts by weight.
6 parts by weight of a low-temperature curable high solids coating composition. 2. A patent in which the acrylic resin of component () (a) is a copolymerized acrylic resin obtained by copolymerization of a mixed monomer in which 50% by weight or less of the acrylic monomer is replaced with another polymerizable ethylenically unsaturated monomer. A high solids coating composition according to claim 1. 3. The high solids coating composition according to claim 1 or 2, which contains an organic solvent in an amount such that the solids content is 50% or more.