JPH083462A - Curable resin composition for coating material - Google Patents

Abstract

PURPOSE:To obtain a curable resin compsn. for coating material capable of forming a coating film which has a high luster, does not discolor in curing, and is excellent in finished appearance and properties such as resistances to impact, water, and scratch. CONSTITUTION:A curable resin compsn. which contains a resin having hydroxyl, carboxyl, and epoxy groups in the same molecule, a silicon compd. having at least one silanol group and/or at least one hydrolyzable group directly bonded to a silicon atom, and an org. solvent as the essential components.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel curable resin composition for paints.

[0002]

2. Description of the Related Art Cross-linking and curing a resin based on a reaction between an epoxy group and a carboxyl group is widely used as a means for curing a paint film. For example, there are a mixed type of an epoxy group-containing resin and a carboxyl group-containing resin, or a self-crosslinking type having both functional groups in the same molecule.

The latter self-crosslinking type resin is prepared, for example, by polymerizing a monomer component containing a glycidyl group-containing polymerizable unsaturated monomer and a carboxyl group-containing polymerizable unsaturated monomer as main components ( See, for example, JP-A-63-135465.

However, in this method, each functional group of both unsaturated monomers reacts during or before the polymerization to cause gelation or partial polymerization, so that a sufficient amount of the functional group for curing is obtained. It is difficult to introduce a group.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems. As a result, an organic solvent solution or dispersion containing a resin containing a hydroxyl group, a carboxyl group and an epoxy group in the same molecule and a specific silicon compound has no discoloration during curing and has excellent low temperature curability. Therefore, the present invention has been completed.

That is, the present invention provides (a) a resin containing a hydroxyl group, a carboxyl group and an epoxy group in the same molecule,
(B) at least one silanol group in one molecule and /
Alternatively, the present invention relates to a curable resin composition for coatings, which contains a silicon compound having a hydrolyzable group directly bonded to a silicon atom and (c) an organic solvent as essential components.

In the present invention, the silanol group means a hydroxyl group directly bonded to a silicon atom, and the hydrolyzable group directly bonded to a silicon atom means a group which produces a silanol group by hydrolysis.

The resin (a) in the present invention is a base resin containing a hydroxyl group, a carboxyl group and an epoxy group in the same molecule.

The carboxyl group in the resin (a) is one of the important constitutional requirements in the present invention. That is, the carboxyl group is composed of a hydroxyl group in the resin (a) and a silanol group in the silicon compound (b) (including a silanol group produced by hydrolysis of a hydrolyzable group directly bonded to a silicon atom). The function of accelerating the reaction and the reaction of silanol groups is recognized, and the effect of improving low temperature curability is obtained by this, and this carboxyl group reacts with the epoxy group, and a cured film with excellent performance such as acid resistance. Along with the formation of the carboxyl group, the carboxyl group is consumed in the reaction with the epoxy group, and the carboxyl group does not remain in the coating film or remains in a small amount, so that the coating film has water resistance, acid resistance, scratch resistance, and weather resistance. And so on.

The hydroxyl group in the resin (a) has a hydroxyl value of about 1
An amount in the range of 0 to 300, preferably about 20 to 200 is good. When the hydroxyl value is less than about 10, the low temperature curing property, durability and the like of the coating film are deteriorated, while when the hydroxyl value exceeds about 300, the number of unreacted hydroxyl groups remaining in the coating film is increased, so that the water resistance of the coating film is increased. It is not preferable because it deteriorates the properties.

The amount of the carboxyl group in the resin (a) is about 3 to 150, preferably about 5 to 80 in terms of acid value. When the acid value is less than about 3, low temperature curability and the like decrease,
On the other hand, if the acid value exceeds about 150, the water resistance and weather resistance of the coating film will deteriorate, which is not preferable.

The epoxy group in the resin (a) is in an amount such that the epoxy value is in the range of about 0.1 to 4.0, preferably about 0.2 to 3.0. When the epoxy value is less than about 0.1, the low temperature curability is deteriorated, while when the epoxy value is more than about 4.0, the acid resistance and weather resistance of the coating film are deteriorated, which is not preferable.

The resin (a) has a number average molecular weight of about 30.
00-200000, preferably about 5000-8000
The range of 0 is good. When the number average molecular weight is less than about 3,000, the durability of the coating film is deteriorated, while when the number average molecular weight exceeds about 200,000, an organic solvent (d) necessary for dilution is obtained.
It is not preferable because there is a drawback that the solid content of the coating material becomes low due to the large amount.

The type of the resin (a) is not particularly limited, and conventionally known ones can be appropriately selected and used, but acrylic resins are preferable from the viewpoint of weather resistance and durability of the coating film. .

Specific examples of the acrylic resin include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, (poly) ethylene glycol mono (meth) acrylate and (poly) propylene glycol. Hydroxyl group-containing acrylic monomers such as mono (meth) acrylate and adducts of these with caprolactone (ε-caprolactone etc.); (meth) acrylic acid;
(Anhydrous) maleic acid and other carboxyl group-containing ethylenically unsaturated monomers; glycidyl (meth) acrylate,
Glycidyl group-containing monomers such as methyl glycidyl (meth) acrylate and allyl glycidyl ether; 3,4-
A radically polymerizable epoxy group-containing monomer such as an alicyclic epoxy group-containing monomer such as epoxycyclohexylmethyl (meth) acrylate is used as an essential monomer component, and if necessary, other radically polymerizable unsaturated monomers,
For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate and cyclohexyl (meth).
C _1-24 alkyl (meth) acrylates or cycloalkyl (meth) acrylates such as acrylates; aromatic vinyl monomers such as styrene and vinyltoluene; nitrile compounds such as (meth) acrylonitrile; (meth)
Those obtained by copolymerizing other ethylenically unsaturated monomers such as amide compounds such as acrylamide and N-methylol (meth) acrylamide are included.

Further, as a method of synthesizing the resin (a), it is obtained by copolymerizing the hydroxyl group-containing acrylic monomer, the radically polymerizable epoxy group-containing monomer, and other radically polymerizable unsaturated monomers, if necessary. Also included is a method in which a cyclic acid anhydride (A-2) is subjected to a ring-opening half-esterification reaction with the hydroxyl group of the epoxy group-containing resin (A-1). The cyclic acid anhydride (A-2) used at that time is a compound having one or more carboxylic acid cyclic acid anhydride groups in one molecule, and examples thereof include phthalic anhydride, succinic anhydride, and tetrahydrophthalic anhydride. Acid, tetrabromophthalic anhydride, tetrachlorophthalic anhydride, het anhydride, hymic acid anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride and the like,
These can be used alone or in combination of two or more.

The model of the ring-opening half-esterification reaction between the hydroxyl group of the resin (A-1) and the cyclic acid anhydride (A-2) is, as a model, 1 mol of the hydroxyl group of the cyclic acid anhydride (A-2). This is a reaction in which moles react to open the cyclic acid anhydride group to generate 1 mole of a free carboxyl group. This ring-opening half-esterification reaction can be carried out by a method known per se,
For example, it can be performed in an organic solvent at a temperature of about 40 to about 100 ° C. At that time, a catalyst such as an organic tin compound, an organic titanium compound, or an organic zirconium compound can be used to accelerate the reaction.

The silicon compound (b) in the present invention has at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule, and is a crosslinker component of the resin (a). Is.

The hydrolyzable group is a residue which is hydrolyzed in the presence of water to form a silanol group, and examples thereof include a C _1-3 alkoxyl group such as methoxy, ethoxy and propoxy, acetoxy and propionyloxy. And the like acyloxy group and the like.

Examples of the silicon compound (b) include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane,
If necessary, a radically polymerizable unsaturated group-containing silicon compound such as β- (meth) acryloyloxyethyltrimethoxysilane may be added to, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate. , (Poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol mono (meth) acrylate, and hydroxyl group-containing acrylic monomers such as adducts of these with caprolactone (ε-caprolactone etc.), (meth )
Acrylic acid, carboxyl group-containing ethylenically unsaturated monomers such as (anhydrous) maleic acid, glycidyl (meth) acrylate, methylglycidyl (meth) acrylate,
Glycidyl group-containing monomers such as allyl glycidyl ether, radically polymerizable epoxy monomers such as alicyclic epoxy group-containing monomers such as 3,4-epoxycyclohexylmethyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meta)
C _1-24 alkyl (meth) acrylate or cycloalkyl (meth), such as acrylate, butyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate and cyclohexyl (meth) acrylate. ) Acrylates, aromatic vinyl monomers such as styrene and vinyltoluene, nitrile compounds such as (meth) acrylonitrile, and other ethylenic compounds such as amide compounds such as (meth) acrylamide and N-methylol (meth) acrylamide. A polymer obtained by a radical polymerization reaction with a saturated monomer, preferably having an average molecular weight of about 3,000 to
In the range of about 200,000; General formula Si (OR) ₄ (I) (wherein R is the same or different, is a hydrogen atom or C _1-3.
Is an alkyl group. ) A silicon monomer represented by the formula; a low condensate of the silicon monomer; a low condensate of the silicon monomer, wherein a part of R in the low condensate is C _4-24 (preferably C _4-8 ). A modified silicon condensate substituted with a monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond);
Or obtained by reacting the modified silicon condensate with an ethylenically unsaturated monomer containing a functional group capable of reacting with one ethylenically unsaturated group and SiOR group (R is the same as above) in one molecule. A silicon condensate containing an ethylenically unsaturated group,
Polymers obtained by radical polymerization reaction with the above-mentioned other ethylenically unsaturated monomers, if necessary, preferably having an average molecular weight of about 3,000 to 200,000 are included.

In the above silicon compound (b), a low condensation product of a silicon monomer and a modified silicon condensation product can form a coating film having a high solid content, low cost, and various performances, and thus can be advantageously used. . Further, when a modified silicon condensate or a polymer using the same is used as the silicon compound (b), the resulting coating film is particularly advantageous in that it has excellent finish and acid resistance.

The low-condensation product of the above-mentioned silicon monomer is about 2-1 obtained by subjecting the above-mentioned silicon monomers to a condensation reaction.
A 00-mer, preferably about 2 to 10-mer, is suitable. Examples of the low-condensation product of the silicon monomer include "Colcoat ES40" (trade name, manufactured by Colcoat Co., Ltd., hereinafter, similarly, 1 to 10 mer of tetraethyl silicate, average of about 5 mer), "Colcoat MS51" (tetramethyl silicate). 1 to 10 mer, average about 4 mer) and the like. These low-condensates made by Colcoat are generally

[0023]

Embedded image

It is considered to have a structure of (n is 1 to 10).

The C _4-24 monovalent hydrocarbon group in the modified silicon condensate is, for example, a cyclic or linear branched chain such as butyl, pentyl, hexyl, heptyl, octyl, decyl, stearyl, cycloalkyl and the like. It includes an optionally substituted alkyl group, an aryl group such as phenyl, toluyl, xylyl and the like, an aralkyl group such as benzyl (an alkyl group substituted with an aryl group) and the like.

The hydrocarbon group containing an ether bond is, for example,

[0027]

Embedded image

(Where m is 1, 2 or 3, p is 1 or 2 and _R'is a C _1-8 alkyl group),

[0029]

Embedded image

(In the formula, m has the same meaning as described above.)
Etc. are included. In particular,

[0031]

[Chemical 4]

And the like.

The hydrocarbon group containing an ester bond is, for example,

[0034]

Embedded image

(In the formula, R ″ represents a C _1-8 cyclic or linear alkyl group which may be branched, an aryl group or an aralkyl group, and m represents the same meaning as described above. .)
Etc. are included. In particular,

[0036]

[Chemical 6]

And the like.

Further, the hydrocarbon group containing both ether bond and ester bond is, for example,

[0039]

[Chemical 7]

(In the formula, q is an integer of 2 or more, preferably 2
Is an integer of 10 and m and R ″ have the same meanings as described above.) And the like.

[0041]

Embedded image

And the like.

The modified silicon condensate is prepared, for example, by using a monomer in which a part of R in the silicon monomer is replaced by a C _4-24 monovalent hydrocarbon group as a starting material, and subjecting this to a condensation reaction. or low condensate with C _4-24 alcohol (ether bond and / or may contain an ester bond) and the hydrocarbon part of the R of Teichijimigobutsu by dealcoholization C _4-24 of the silicon monomer It can be produced by substituting with a group.

The polymer of the ethylenically unsaturated group-containing silicon condensate is a functional group capable of reacting with the SiOR group contained in the low condensate of the silicon monomer or the modified silicon condensate (for example,
An ethylenically unsaturated monomer having one or more active hydrogen groups such as hydroxyl groups in one molecule and one ethylenically unsaturated group in one molecule is a low condensation product of silicon monomers and / or modified silicon condensation. Alcohol reacts with the substance to produce the SiOR
After substituting a part of R of the group with an ethylenically unsaturated monomer to produce an ethylenically unsaturated group-containing silicon condensate containing an average of about 1 ethylenically unsaturated group in one molecule, this is used alone Or by radical polymerization reaction of this with the other ethylenically unsaturated monomer.

Examples of the ethylenically unsaturated monomer having a functional group that reacts with the SiOR group and an ethylenically unsaturated group include, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, (Poly) ethylene glycol mono (meth) acrylate, (poly) propylene glycol (meth) acrylate, hydroxyethyl vinyl ether, hydroxypropyl vinyl ether,
Hydroxyl vinyl ether, (poly) ethylene glycol monoallyl ether, and hydroxyl group-containing ethylenically unsaturated monomers such as adducts of these with caprolactone are preferred.

When a polymer is used as the above-mentioned silicon compound (b), if the average molecular weight thereof is less than about 3000, the coating film performance such as acid resistance tends to decrease, while about 20,000.
When it exceeds 0, the solid content of the coating composition tends to decrease and the finished appearance of the coating film tends to deteriorate, such being undesirable.

The above-mentioned components (a) and (b) are preferably blended in the following proportions. The ratio is a value based on the total measurement of the components (a) and (b).

Component (a): The amount is in the range of about 30 to 98% by weight, preferably about 50 to 95% by weight, and when it is less than about 30% by weight, the base resin component in the composition is reduced, so that the coating film is finished. The appearance and performance are deteriorated, while if it exceeds about 98% by weight, the solid content of the resin composition is decreased and the curability is decreased, which is not preferable.

Component (b): About 2 to 70% by weight, preferably about 5 to 50% by weight, and if it is out of the range, the curability is deteriorated, which is not preferable.

The organic solvent (c) in the present invention is a component which dissolves or disperses the components (a) and (b).
The organic solvent (c) is not particularly limited as long as it can dissolve or disperse the components (a) and (b), and can be appropriately selected and used from conventional organic solvents.

Specific examples of the organic solvent (c) include aromatic hydrocarbons such as toluene and xylene, acetone,
Examples thereof include ketone systems such as methyl ethyl ketone and methyl isobutyl ketone, ester systems such as ethyl acetate, propyl acetate and butyl acetate, and alcohol systems such as ethylene glycol monobutyl ether.

The organic solvent (c) is blended so that the solid content of the resin composition is usually in the range of about 10 to 70% by weight.

The composition of the present invention comprises the above-mentioned (a) to (c).
In addition to the components, a curing catalyst, a coloring pigment, an extender pigment, an ultraviolet absorber, an ultraviolet stabilizer, a fluidity adjusting agent, and other additives for paints can be added as necessary.

The composition of the present invention can be applied directly to a base material such as metal or plastic, or to a coated base material obtained by coating these materials. The coating film thickness is about 1 to dry film thickness.
The range of 100 μm, preferably about 10 to 50 μm is good, and the curing conditions are such that heating at a temperature of about 60 to 260 ° C. cures for about 1 to 180 minutes.

[0055]

According to the composition of the present invention, high gloss, no discoloration upon curing, excellent finished appearance, and impact resistance,
It is possible to form a coating film having excellent properties such as water resistance and scratch resistance.

[0056]

EXAMPLES The present invention will be described more specifically below with reference to production examples, examples and comparative examples.

Production Example 1 Production of Resin (a) 2-Hydroxyethyl Methacrylate 130 g Acrylic Acid 36 g Glycidyl Methacrylate 142 g Isobutyl Methacrylate 492 g Styrene 200 g Azobisdimethylvaleronitrile 70 g A mixture was added dropwise to 1000 g of xylene at 80 ° C.
Acrylic polyol having a number average molecular weight of 8000 (hydroxyl value = 56, acid value = 25, epoxy value =
0.95) was obtained.

Production Example 2 Production of resin (b) 2-hydroxyethyl methacrylate 2 mol / kg, glycidyl methacrylate 2 mol / kg, styrene 200
2,000 g of a 50% xylol solution of an acrylic polyol (number average molecular weight of 8500) consisting of g / kg and the balance of n-butyl methacrylate was mixed with 148 g of phthalic anhydride and 0.5 g of butyltin laurate and the acid was added at 50 ° C. for 6 hours. A ring-opening reaction of an anhydrous group is performed to obtain an acrylic polyol having a number average molecular weight of 10,000 (hydroxyl value = 49,
Acid value = 48, epoxy value = 1.72) was obtained.

Production Example 3 Production of resin (c) 2-hydroxyethyl acrylate 2.5 mol / kg,
Acrylic polyol consisting of 1.5 mol / kg of 3,4-epoxycyclohexylmethyl methacrylate and the balance of n-butyl methacrylate (number average molecular weight 9000)
Succinic anhydride 10 to 2000 g of 50% xylol solution
Add 0 g and butyltin laurate 0.5 g, 50
The acid anhydride group was subjected to ring-opening reaction at 6 ° C. for 6 hours to obtain an acrylic polyol having a number average molecular weight of 10,000 (hydroxyl value = 158, acid value = 50, epoxy value = 1.35).

Production Example 4 Production of Silicon Compound γ-methacryloxypropyltrimethoxysilane 375 g n-butyl acrylate 625 g Azobisisobutyronitrile 20 g A mixture was added dropwise to 1000 g of xylene at 110 ° C.
The reaction was carried out for 8 hours to obtain a silicon compound which was an acrylic resin having a number average molecular weight of 20,000 (average of 30 alkoxysilane groups in one molecule).

Production Example 5 Production of Silicon Compound “Colcoat ES40” 850 g 2-hydroxyethyl methacrylate 150 g Tris (acetylacetonato) aluminum 0.1 g Hydroquinone 1 g A mixture of 53 g was deethanolized at 120 ° C. for 3 hours to give 1 A silicon-containing monomer having an average of one unsaturated bond in the molecule was obtained.

Next, a mixture of the above silicon-containing monomer 300 g hydroxyethyl acrylate 232 g n-butyl methacrylate 468 g azobisisobutyronitrile 30 g was added dropwise to 1000 g of xylene at 100 ° C. 8
The reaction was carried out for a time to obtain a silicon compound which is an acrylic resin having a number average molecular weight of 15,000.

Production Example 6 Production of Silicon Compound “Colcoat ES40” 530 g Benzyl alcohol 470 g Tris (acetylacetonato) aluminum 0.1 g A mixture of 200 g was subjected to ethanol removal reaction at 160 ° C. for 6 hours to obtain a silicon compound. This product has 6 out of 12 ethoxy groups on average in one molecule.

[0064]

[Chemical 9]

Has been replaced by.

Production Example 7 Production of Silicon Compound “Colcoat ES40” 705 g Hydroxyethyl acetate 295 g Tris (acetylacetonato) aluminum 0.1 g A mixture of 44 g was deethanolized at 160 ° C. for 6 hours to obtain a silicon compound. . This one has 3 out of 12 ethoxy groups on average in one molecule.

[0067]

[Chemical 10]

Is replaced by

Production Example 8 Production of Resin (d) Acrylic acid 108 g 2-hydroxyethyl acrylate 232 g Styrene 300 g n-Butyl acrylate 360 g Azobisisobutyronitrile 20 g A mixture of the above was added dropwise to 1000 g of xylene at 110 ° C.
The reaction was carried out for 8 hours to obtain an acrylic polyol having a number average molecular weight of 20,000 (hydroxyl value = 112, acid value = 84).

Production Example 9 Production of Resin (e) 2-Hydroxyethyl Acrylate 232 g Glycidyl Methacrylate 284 g Styrene 200 g 2-Ethylhexyl Methacrylate 284 g Azobisisobutyronitrile A mixture of 20 g was added dropwise to 1000 g of xylene at 110 ° C.
Acrylic polyol having a number average molecular weight of 20,000 after reacting for 8 hours (hydroxyl value = 112, epoxy value = 2.0)
I got

Examples 1 to 18 and Comparative Examples 1 to 6 The various components shown in Table 1 were blended (solid content) and then diluted with xylene so that the resin solid content was 50% by weight. The curable resin composition of was obtained.

[0072]

[Table 1]

Each of the above resin compositions was used as a raw material and had a dry film thickness of 4
It was applied so as to have a thickness of 0 μm and baked at 140 ° C. for 30 minutes to obtain a test coating film. The following coating film performance test was performed on this coating film.

Appearance of coating film: Migaki mild steel plate was used as the material.
The presence or absence of abnormal surface conditions (blur, tingling, cracks, peeling, opacity (smudge)) was examined.

Gloss: A white coated plate was used as a material. 6
The 0 ° specular reflectance (%) was measured.

Gel fraction: A glass plate was used as the material. The coating film was peeled off from the glass plate and extracted with acetone in a Soxhlet extractor at reflux temperature for 6 hours, and then the coating film residue was expressed in%.

Impact resistance: Mild steel plate was used as the material. Using a DuPont impact tester, drop a weight of 500g on the coating surface, and the maximum drop distance (cm) without cracking or peeling of the coating film.
I checked.

Water resistance: Mild steel plate was used as the material. The test piece was immersed in warm water (40 ° C.) for 60 days, and then the presence or absence of an abnormality in the coated surface state (blister, whitening, glossiness, etc.) was examined.

Scratch resistance: A dyed product friction fastness tester (manufactured by Daiei Kagaku Seiki Seisakusho) was used. Polishing powder (Dharma
A cleanser) is kneaded with water and placed on the coated surface, the tester terminals are pressed on the cleanser, and a 0.5 kg load is applied, and 25 reciprocations are performed. After washing with water, the degree of scratches was evaluated according to the following evaluation criteria.

⊚: No change compared to the initial gloss, ◯: Slight gloss was generated compared to the initial gloss, Δ: Gloss was generated compared to the initial gloss, ×: Compared with the initial gloss Caused a remarkable luster.

The test results are shown in Table 2.

[0082]

[Table 2]

Claims (8)

[Claims] 1. A resin containing (a) a hydroxyl group, a carboxyl group and an epoxy group in the same molecule, and (b) at least one silanol group and / or a hydrolyzable group directly bonded to a silicon atom in one molecule. A curable resin composition for a coating material, which comprises a silicon compound having the formula (c) and an organic solvent (c) as essential components. 2. The curable resin composition for coating according to claim 1, wherein the resin (a) has a hydroxyl value of 10 to 300, an acid value of 3 to 150, and an epoxy value of 0.1 to 4.0. Stuff. 3. The resin (a) is obtained by subjecting a resin containing a hydroxyl group and an epoxy group in the same molecule to a ring-opening half-esterification reaction of a cyclic acid anhydride with the hydroxyl group. The curable resin composition for paint according to claim 1. 4. A silicon compound and / or a silicon compound represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). The curable resin composition for coating according to claim 1, which is a low condensation product thereof. 5. A low-condensation silicon compound (b) represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). A thing,
Further, it is a modified silicon condensate in which a part of R in the low condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond). The curable resin composition for paint according to claim 1, wherein 6. A low-condensation silicon compound represented by the general formula Si (OR) ₄ (I), wherein R represents a hydrogen atom or a C _1-3 alkyl group. Ethylenically unsaturated group obtained by reacting a compound with an ethylenically unsaturated monomer having a functional group that reacts with one ethylenically unsaturated group and SiOR group (R is the same as above) in one molecule A curable resin composition for a coating composition according to claim 1, which is a radical polymer containing the contained silicon condensate as a monomer component. 7. A low-condensation silicon compound represented by the general formula Si (OR) ₄ (I) (wherein R represents a hydrogen atom or a C _1-3 alkyl group). A thing,
Further, a modified silicon condensate in which a part of R in the low condensate is substituted with a C _4-24 monovalent hydrocarbon group (which may contain an ether bond and / or an ester bond) and 1 Ethylenically unsaturated group-containing silicon condensation obtained by reacting an ethylenically unsaturated monomer having a functional group that reacts with one ethylenically unsaturated group and a SiOR group (R is the same as above) in the molecule A curable resin composition for a coating composition according to claim 1, which is a radical polymer containing a substance as a monomer component. 8. The curable resin composition for coating composition according to claim 6 or 7, wherein the ethylenically unsaturated monomer is a hydroxyl group-containing ethylenically unsaturated monomer.