WO2015005317A1 - Oxidative curing, alkyd-modified silicone acrylic copolymer - Google Patents

Abstract

This oxidative curing, alkyd-modified silicone acrylic copolymer is obtained by reacting (a) an oxidative curing acrylic copolymer, and (b) a silicone having at least a hydroxyl group and/or an alkoxy group. The oxidative curing acrylic copolymer (a) is a copolymer obtained through graft polymerization of a monomer indicated by (a-1) styrenes, (a-2) (meth)acrylic acid esters, and (a-3) predetermined polymerizable unsaturated monomers, to an alkyd resin (c) having an oxidative polymerizable group.

Description

Oxidation-curable alkyd-modified silicone acrylic copolymer

The present invention relates to an oxidatively curable alkyd-modified silicone acrylic copolymer capable of forming a coating film having excellent initial gloss, weather resistance, initial drying property and impact resistance (strength).

Alkyd resin has oil and fat as a basic component and has an oxidative polymerization property of spontaneously curing by oxidative drying to form a coating film. Therefore, it dries faster than an oil-based blended paint that uses boil oil (long oil) as a film-forming component, and provides a coating film with an initial gloss, and is used for indoor and outdoor iron parts and indoor wood parts of general buildings. It is widely used as a film-forming component for resin blend paints. However, although the alkyd resin is excellent in initial gloss as compared with the acrylic resin and the silicone-modified resin, drying is slow, and the weather resistance and the coating film strength are lowered at the site exposed to ultraviolet rays, wind and rain. Therefore, the paint using the alkyd resin needs to limit the painting range to the indoor part as much as possible.

As a technique for solving this problem of weather resistance, Patent Document 1 discloses a copolymer using cyclohexyl methacrylate, which is a kind of highly weatherable monomer, at a fatty acid-modified acrylic resin or a fatty acid-modified acrylic copolymerization site. A one-part coating composition containing is described.

Patent Document 2 describes an oxidatively curable silicone-modified (meth) acrylic copolymer in which a fatty acid is added to an epoxy group of an epoxy group-containing acrylic copolymer, and a silicone is reacted with a hydroxyl group generated by ring opening of the epoxy group. Has been.

In Patent Document 3, in the presence of a polymer (B) that is soluble in an organic solvent, a vinyl monomer (A) that is difficult to dissolve in an organic solvent is produced by copolymerizing a vinyl monomer, and ( A non-aqueous dispersion type resin having improved weather resistance by modifying A) with silicone is described. Furthermore, it is described that the polymer (B) may be an oil-modified alkyd having an oil length of at least 50%.

Patent Document 4 describes an oxidatively curable silicone-modified vinyl copolymer using a polysiloxane-containing vinyl monomer, which introduces an unsaturated fatty acid into the copolymer molecule or is further modified with an unsaturated alkyd resin. It is described that the oxidative polymerizability is ensured by, for example.

Patent Document 5 describes a copolymer obtained by radical copolymerization of various monomers, an alkyd resin, and a resin obtained by mixing and reacting with a polysiloxane. It is described that this resin is basically used as a lacquer together with a cross-linking material such as polyisocyanate, and can also be imparted with oxidative curability.

JP 2004-211009 A JP 2001-122968 A JP-A-10-158311 JP 2004-091678 A JP 55-005977 A

The copolymer described in Patent Document 1 contains fatty acid which is a soft component having low polarity as a constituent monomer. Therefore, the coating composition containing this copolymer has insufficient weather resistance of the coating film.

The oxidation-curable silicone-modified (meth) acrylic copolymer described in Patent Document 2 has good weather resistance. However, the initial gloss of the coating film is insufficient, and the solubility in a solvent is lowered by further modification with silicone.

In the non-aqueous dispersion type resin described in Patent Document 3, the polymer (B) used as a dispersion stabilizer only surrounds the polymer (A) constituting the inside of the resin. That is, the polymers (A) and (B) are not bonded. Therefore, there is a problem in the weather resistance of the coating film, and there is also a fatal problem in the non-aqueous dispersion that the initial gloss of the coating film is insufficient.

The oxidation-curable silicone-modified vinyl copolymer described in Patent Document 4 has insufficient weather resistance and initial gloss.

In the resin described in Patent Document 5, a vinyl copolymer polymerized in advance is reacted with an alkyd resin and polysiloxane in the production process. Therefore, structurally, the alkyd resin and the copolymer are not directly bonded but are bonded via the polysiloxane. Therefore, the balance between the alkyd resin, the copolymer and the polysiloxane is poor, the crosslinking reaction does not easily proceed during the formation of the coating film, and the weather resistance and impact resistance (strength) of the coating film are insufficient.

The problem of the present invention is that the initial gloss of the coating film is high and the alkyd resin is a conventional silicone-modified resin, which cannot be realized by the resins and copolymers disclosed in Patent Documents 1 to 5 or conventional silicone-modified resins. The object of the present invention is to provide an oxidatively curable alkyd-modified silicone acrylic copolymer which is a coating film forming component satisfying weather resistance, initial drying property and impact resistance (strength) which are inferior to those of the above.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) Oxidation-curable acrylic copolymer obtained by graft polymerization of the following monomers (a-1), (a-2) and (a-3) to an alkyd resin (c) having an oxidation-polymerizable group An oxidatively curable alkyd-modified silicone acrylic copolymer obtained by reacting the union (a) with a silicone (b) having at least one of a hydroxyl group and an alkoxy group, wherein the alkyd resin (c), The alkyd resin (c) is 8 with respect to the total amount of styrenes (a-1), (meth) acrylic acid ester (a-2), polymerizable unsaturated monomer (a-3), and silicone (b). An oxidatively curable alkyd-modified silicone resin comprising: -40 mass%, styrenes (a-1) 10-30 mass%, and silicone (b) 5-15 mass% Lil copolymer.
(A-1) Styrenes (a-2) (Meth) acrylic acid ester (a-3) Polymerization having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group (2) The styrenes (a-1), the (meth) acrylic acid ester (a-2), and the polymerizable unsaturated monomer (a-3) are styrenes (a-1). The oxidatively curable alkyd-modified product according to (1), which is contained in the following ratio with respect to the total amount of (meth) acrylic acid ester (a-2) and polymerizable unsaturated monomer (a-3) Silicone acrylic copolymer.
(A-1) Styrenes: 13 to 40% by mass
(A-2) (Meth) acrylic acid ester: 53 to 86% by mass
(A-3) Polymerizable unsaturated monomer: 1 to 7% by mass
(3) The styrenes (a-1), the (meth) acrylic acid ester (a-2), and the polymerizable unsaturated monomer (a-3) are contained in an oxidatively curable alkyd-modified silicone acrylic copolymer. The oxidatively curable alkyd-modified silicone acrylic copolymer according to (1) or (2), which is contained in a total amount of 45 to 87% by mass.
(4) The oxidation-curable alkyd-modified silicone acrylic copolymer according to any one of (1) to (3), having a solid iodine value of 5 to 50.
(5) The oxidation-curable alkyd-modified silicone acrylic copolymer according to any one of (1) to (4), which has a weight average molecular weight of 10,000 to 150,000.
(6) The oxidation-curable alkyd-modified silicone acrylic copolymer according to any one of (1) to (5), wherein the silicone (b) further has a phenyl group.
(7) Oxidation-curable acrylic copolymer obtained by graft polymerization of the following monomers (a-1), (a-2) and (a-3) to alkyd resin (c) having an oxidative polymerizable group An alkyd resin (c) comprising a step of obtaining (a), a step of reacting the obtained oxidatively curable acrylic copolymer (a) with a silicone (b) having at least one of a hydroxyl group and an alkoxy group. Alkyd resin (c) with respect to the total amount of styrenes (a-1), (meth) acrylic acid ester (a-2), polymerizable unsaturated monomer (a-3), and silicone (b) The oxidatively curable alkyd-modified silicone acrylic copolymer is used in an amount of 8 to 40% by mass, styrenes (a-1) 10 to 30% by mass, and silicone (b) 5 to 15% by mass. Polymer Manufacturing method.
(A-1) Styrenes (a-2) (Meth) acrylic acid ester (a-3) Polymerization having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group Unsaturated monomers.

The oxidatively curable alkyd-modified silicone acrylic copolymer of the present invention contains alkyd resin (c), styrenes (a-1) and silicone (b) in a predetermined ratio, and this is used as a coating film forming component. When used, a coating film having high initial gloss and satisfactory weather resistance, initial drying property and impact resistance (strength) can be obtained.

The oxidation-curable alkyd-modified silicone acrylic copolymer according to the present invention (hereinafter sometimes simply referred to as “the copolymer of the present invention”) includes an oxidation-curable acrylic copolymer (a), a hydroxyl group and an alkoxy group. It is obtained by reacting with silicone (b) having at least one of groups (hereinafter sometimes simply referred to as “silicone (b)”).

(Oxidation-curing acrylic copolymer (a))
The oxidatively curable acrylic copolymer (a) used in the present invention includes an alkyd resin (c) having an oxidative polymerizable group, the following (a-1), (a-2) and (a-3): It is obtained by graft polymerization of the monomers shown.
(A-1) Styrenes (a-2) (Meth) acrylic acid ester (a-3) Polymerization having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group Unsaturated monomer (hereinafter, sometimes simply referred to as “polymerizable unsaturated monomer”).

<Alkyd Resin (c) Having Oxidatively Polymerizable Group>
The alkyd resin is a kind of polyester resin and can be obtained by condensing a polyhydric alcohol and a polybasic acid. In the present invention, among alkyd resins, an alkyd resin (c) having an oxidative polymerizable group (hereinafter sometimes simply referred to as “alkyd resin (c)”) is used.

The oxidative polymerizable group possessed by the alkyd resin (c) is, for example, an unsaturated carbon bond (carbon double bond or carbon triple bond) derived from an unsaturated fatty acid. That is, the alkyd resin (c) is obtained by introducing an unsaturated fatty acid into the alkyd resin. The unsaturated fatty acid is not particularly limited as long as it is a fatty acid having at least one unsaturated carbon bond in the molecule. The unsaturated fatty acid used in the present invention preferably has a solid iodine value that is somewhat high (that is, has a lot of unsaturated carbon bonds). Examples of such unsaturated fatty acids include dry oil fatty acids and semi-dry oil fatty acids. Is mentioned. Dry oil fatty acids and semi-dry oil fatty acids are not strictly distinguishable, but usually dry oil fatty acids are unsaturated fatty acids having a solid iodine value of 130 or more, and semi-dry oil fatty acids have a solid iodine value of 100 or more and Less than 130 unsaturated fatty acids. The non-drying oil fatty acid is usually a fatty acid having a solid iodine value of less than 100.

Examples of the dry and semi-dry oil fatty acids include fish oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp oil fatty acid, grape Examples include nuclear oil fatty acid, corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid, hydienoic acid fatty acid, oleic acid, linoleic acid, and linolenic acid. These dry oil fatty acids and semi-dry oil fatty acids are non-dry oil fatty acids (for example, coconut oil fatty acid, hydrogenated coconut oil fatty acid, palm oil fatty acid, etc.), caproic acid, capric acid, lauric acid, myristic acid as necessary. , Palmitic acid, stearic acid and the like may be used in combination.

Furthermore, in the present invention, fats and oils (glycerides) may be used together with unsaturated fatty acids or instead of unsaturated fatty acids. The fats and oils are those having unsaturated carbon bonds, such as fish oil, dehydrated castor oil, safflower oil, linseed oil, soybean oil, sesame oil, poppy oil, eno oil, hemp seed oil, grape kernel oil, corn oil , Dry oil or semi-dry oil such as tall oil, sunflower oil, cottonseed oil, walnut oil, rubber seed oil.

The oil length of the alkyd resin (c) is preferably 30 to 70%. In this specification, "oil length" means the ratio (mass%) of the fatty acid or fats and oils in alkyd resin (c) raw material. The oil length is obtained by the following formula.
Oil length (%) = (mass of fatty acid or fat / total mass of alkyd resin (c) raw material) × 100
When the oil length is in such a range, when the obtained copolymer is used as a coating film-forming component, it is rich in oxidative curability, has a high crosslinking density, has a high initial gloss, and has weather resistance and initial drying properties. An excellent coating film can be obtained. Furthermore, hydrocarbon groups derived from fatty acids and fats and oils are appropriately introduced into the molecule of the alkyd resin (c), and the solubility in a solvent is further improved when preparing a coating composition. The oil length is more preferably 40 to 60%.

The alkyd resin (c) is obtained by subjecting a polyhydric alcohol, a polybasic acid, and an unsaturated fatty acid (or oil) to a condensation reaction (or transesterification reaction). Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, glycerin, pentaerythritol, mannitol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, hexanediol, trimethylolpropane, dipentaerythritol, And D-sorbitol. Examples of the polybasic acid include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, succinic anhydride, maleic acid, maleic anhydride, adipic acid, sebacic acid, and tetrahydrophthalic anhydride. If necessary, monobasic acids such as benzoic acid, t-butylbenzoic acid, hexahydrobenzoic acid and cinnamic acid can be used in combination.

These raw materials may be mixed and reacted usually at 170 to 280 ° C. for 3 to 15 hours under normal pressure or pressure. In the reaction, a solvent (for example, xylene, toluene, methyl isobutyl ketone, etc. can be used. Other usable solvents will be described later) may be used. Thus, an alkyd resin (c) having an unsaturated fatty acid residue introduced into the molecule is obtained. Furthermore, you may use a well-known catalyst as needed.

The oxidatively curable acrylic copolymer (a) used in the present invention is obtained by graft polymerization of the monomers (a-1), (a-2) and (a-3) to the alkyd resin (c). Can be obtained.

<Styrenes (a-1)>
Styrenes (a-1) are used for improving the initial gloss of the coating film. The styrenes (a-1) used in the present invention are not particularly limited, and examples thereof include styrene, α-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-tert-butyl styrene and the like. Can be mentioned. Among these, styrene is preferable from an economical viewpoint and availability. These styrenes (a-1) may be used alone or in combination of two or more. The styrenes (a-1) are preferably used in a proportion of 13 to 40% by mass with respect to the total amount of the above (a-1), (a-2) and (a-3). Generally, when a large amount of styrene (a-1) is used, impact resistance (strength) and weather resistance tend to be lowered. In the present invention, the balance with other monomers ((a-2) and (a-3)) and the alkyd resin in spite of setting a relatively large amount of styrenes (a-1). By the balance with (c) and silicone (b) described later, the initial gloss and initial drying properties of the coating film can be further improved without substantially reducing the impact resistance (strength) and weather resistance of the coating film. Styrenes (a-1) are more preferably used in a proportion of 20 to 33% by mass.

<(Meth) acrylic acid ester (a-2)>
The (meth) acrylic acid ester (a-2) is used for imparting flexibility and weather resistance to the coating film. In the present specification, “(meth) acryl” means “acryl” or “methacryl”. The (meth) acrylic acid ester (a-2) used in the present invention is not particularly limited, and examples thereof include alkyl (meth) acrylate having an alkyl group having 1 to 18 carbon atoms. Specific examples of (meth) acrylic acid esters include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, (meth ) N-butyl acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, Lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, dialkylaminoalkyl (meth) acrylate (eg, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate) Etc.

Furthermore, as the (meth) acrylic acid ester (a-2), a (meth) acrylic acid ester containing a fluorine atom in the molecule may be used. Examples of such (meth) acrylic acid esters include (meth) acrylic acid esters having 3 to 17 fluorine atoms in the molecule. The (meth) acrylic acid ester containing a fluorine atom in the molecule is commercially available from, for example, Osaka Organic Chemical Industry Co., Ltd. under the following product name.
Biscoat 3F (acrylic ester monomer containing 3 fluorine atoms)
Biscoat 4F (acrylic ester monomer containing 4 fluorine atoms)
Biscote 8F (acrylic ester monomer containing 8 fluorine atoms)
Biscoat 12F (acrylic ester monomer containing 12 fluorine atoms)
Biscote 17F (acrylic acid ester monomer containing 17 fluorine atoms)
Among these, n-butyl acrylate, i-butyl methacrylate, and t-butyl methacrylate are preferable. These (meth) acrylic acid esters (a-2) may be used alone or in combination of two or more.

In addition, the compound generally classified into (meth) acrylic acid ester may overlap with the compound classified into the polymerizable unsaturated monomer (a-3) mentioned later depending on the kind. For example, hydroxymethyl (meth) acrylate is classified as (meth) acrylic acid ester and polymerizable unsaturated monomer. The (meth) acrylic acid ester having such a polar functional group is classified as “polymerizable unsaturated monomer (a-3)” in the present specification. Examples of the polar functional group include a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group.

The (meth) acrylic acid ester (a-2) is preferably used in a proportion of 53 to 86% by mass with respect to the total amount of the above (a-1), (a-2) and (a-3). . By using (meth) acrylic acid ester (a-2) in such a proportion, the flexibility and weather resistance of the coating film can be further improved without substantially reducing the initial gloss and impact resistance (strength) of the coating film. Can be increased. The (meth) acrylic acid ester (a-2) is more preferably used in a proportion of 64 to 79% by mass.

<Polymerizable unsaturated monomer (a-3)>
The polymerizable unsaturated monomer (a-3) is used to introduce silicone (b) described later into the copolymer (that is, to bond the oxidatively curable acrylic copolymer (a) and the silicone (b)). Used. The polymerizable unsaturated monomer (a-3) is a polymerizable unsaturated monomer having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group in the molecule. There is no particular limitation. Among these, a polymerizable unsaturated monomer having a hydroxyl group or a carboxyl group in the molecule is preferable. These polymerizable unsaturated monomers (a-3) may be used alone or in combination of two or more.

Examples of the polymerizable unsaturated monomer having a hydroxyl group include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 1-methyl (meth) acrylate. Examples thereof include hydroxyl group-containing (meth) acrylic acid esters such as 2-hydroxyethyl, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Of these, 2-hydroxyethyl (meth) acrylate is preferred.

Examples of the polymerizable unsaturated monomer having a carboxyl group include α, β-unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, maleic acid and fumaric acid or salts thereof; Examples include half esterified products of acid esters and acid anhydrides. Among these, α, β-unsaturated carboxylic acids are preferable, (meth) acrylic acid is more preferable, and methacrylic acid is more preferable.

Examples of the polymerizable unsaturated monomer having a glycidyl group include glycidyl group-containing (meth) acrylic acid esters such as glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and allyl glycidyl ether. Among these, glycidyl (meth) acrylate is preferable.

Examples of the polymerizable unsaturated monomer having an isocyanate group include isocyanatomethyl (meth) acrylate, 2-isocyanatoethyl (meth) acrylate, 3-isocyanatopropyl (meth) acrylate, and (meth) acrylic acid. Examples thereof include isocyanate group-containing (meth) acrylic esters such as 1-methyl-2-isocyanatoethyl, 2-isocyanatopropyl (meth) acrylate, and 4-isocyanatobutyl (meth) acrylate. Of these, 2-isocyanatoethyl (meth) acrylate is preferred.

The polymerizable unsaturated monomer (a-3) is preferably used in a ratio of 1 to 7% by mass with respect to the total amount of the above (a-1), (a-2) and (a-3). By using the polymerizable unsaturated monomer (a-3) in such a proportion, the reaction with the silicone (b) proceeds moderately, and the weather resistance of the coating film is almost reduced without substantially reducing the initial gloss of the coating film. In addition, impact resistance (strength) can be further increased. Furthermore, the viscosity of the coating composition does not become too high. The polymerizable unsaturated monomer (a-3) is more preferably used in a proportion of 1 to 3% by mass.

The method for graft polymerizing these (a-1), (a-2) and (a-3) to the alkyd resin (c) is not particularly limited. For example, polymerization may be performed in an inert gas atmosphere such as nitrogen gas or argon gas using light irradiation or a polymerization initiator shown below. Usually, the reaction temperature is 50 to 150 ° C., and the reaction time is 3 to 20 hours. More specifically, for example, a method of dropping a mixture of a monomer and a polymerization initiator into a reaction vessel containing an alkyd resin, a remaining monomer and a polymerization initiator in a reaction vessel containing an alkyd resin and a part of the monomer And a method of dropping a polymerization initiator into a reaction vessel containing an alkyd resin and a monomer, a method of dropping an alkyd resin and a polymerization initiator into a reaction vessel containing a monomer, and the like.

The polymerization initiator is not particularly limited, and is appropriately selected according to the type of monomer and reaction conditions. Specific examples include radical polymerization initiators and photopolymerization initiators. These polymerization initiators may be used alone or in combination of two or more.

Examples of radical polymerization initiators include azo compounds, peroxide compounds, sulfides, sulfines, sulfinic acids, diazo compounds, and resox compounds. Among these, an azo compound or a peroxide compound is preferable.

Examples of the azo compound include azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanenitrile, 1,1′-azobis (1-acetoxy-1-phenylethane), dimethyl 2,2′-azo. Examples thereof include bisisobutyrate and 4,4′-azobis-4-cyanovaleric acid.

Examples of the peroxide compounds include benzoyl peroxide, lauroyl peroxide, acetyl peroxide, capryel peroxide, 2,4-dichlorobenzoyl peroxide, isobutyl peroxide, acetylcyclohexylsulfonyl peroxide, and t-butyl peroxide. Oxybiparate, t-butylperoxy-2-ethylhexanoate, 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane 1,1-di-t-hexylperoxy-3,3,5-trimethylcyclohexane, isopropyl peroxydicarbonate, isobutyl peroxydicarbonate, s-butyl peroxydicarbonate, n-butyl peroxydi -Bonate, 2-ethylhexyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-amylperoxy-2-ethylhexaenoate, 1,1,3,3-tetramethylbutylperoxy -Ethylhexanoate, 1,1,2-trimethylpropylperoxy-2-ethylhexanoate, t-butylperoxyisopropyl monocarbonate, t-amylperoxyisopropyl monocarbonate, t-butylperoxy-2- Ethylhexyl carbonate, t-butyl peroxyallyl carbonate, t-butyl peroxyisopropyl carbonate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl Monomonocarbonate, 1,1,3,3-tetramethylbutylperoxyisononate, 1,1,2-trimethylpropylperoxy-isononate, t-butylperoxybenzoate, t-hexylperoxyisopropylmonocarbonate, and organic peroxides such as t-amylperoxy-3,5,5-trimethylhexanoate.

Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 1-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl. -Propan-1-one, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, 2-methyl-1- [4- (methylthio) Phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, bis (2,4,6-trimethylbenzoyl) -phenylphos Fin oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 4-methylbenzophenone, etc. And the like.

The alkyd resin (c) and the mixture of (a-1), (a-2) and (a-3) are an alkyd resin (c) and styrenes (a-1), which are described later. What is necessary is just to mix so that it may become a ratio contained in a polymer.

Furthermore, monomers other than (a-1) to (a-3) may be polymerized to the alkyd resin (c) within a range not impairing the effects of the present invention. Examples of monomers other than (a-1) to (a-3) include (meth) acrylonitrile, (meth) acrylamide, vinyl acetate, vinyl chloride, vinyl pyrrolidone, vinyl oxazoline, acryloylmorpholine, and the like. The content of monomers other than the above (a-1) to (a-3) is included in the oxidatively curable alkyd-modified silicone acrylic copolymer in a total amount of 5% by mass or less, preferably 2% by mass or less. It is.

By such a method, a mixture of (a-1), (a-2) and (a-3) can be graft polymerized to the alkyd resin (c). By graft polymerization of a mixture of (a-1), (a-2) and (a-3) to an alkyd resin, the impact resistance (strength), weather resistance, initial gloss and initial drying properties of the coating film are improved. Can be improved.

(Silicone (b) having at least one of hydroxyl group and alkoxy group)
The silicone (b) used in the present invention is, for example, a branched chain having a siloxane bond (—Si—O—Si—) as the main chain and a substituent such as an alkyl group, an aryl group, a hydroxyl group or an alkoxy group in the side chain. The polysiloxane having a structure is not particularly limited as long as it is a silicone having at least one of a hydroxyl group and an alkoxy group.

It is preferable that at least one of the hydroxyl group or the alkoxy group is directly bonded to at least one silicon atom in the silicone molecule.

Silicone (b) is represented, for example, by the formula R ¹ _m (R ² O) _n SiO _{(4-mn) / 2} .
Wherein R ¹ and R ² are the same or different and each represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and m is 0 ≦ m ≦ 3 .5 and n satisfies 0.0005 ≦ n <4). Since silicone (c) is a mixture of molecules having different degrees of polymerization and functional group substitution, the values of m and n in the above formula are not necessarily integers.

Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group. Among these, an alkyl group having 1 to 3 carbon atoms is preferable in terms of imparting weather resistance to the coating film. Furthermore, a propyl group (n-propyl group or isopropyl group) is more preferable from the viewpoint of solubility in a solvent. When the number of carbon atoms is 3 or more, it may be a cyclic alkyl group.

Examples of the aryl group having 6 to 12 carbon atoms include phenyl group, benzyl group, tolyl group, xylyl group, and naphthyl group. Among these, an aryl group having 6 to 8 carbon atoms is preferable, and a phenyl group is more preferable.

The silicone (b) is preferably a silicone further having a phenyl group in addition to a hydroxyl group or an alkoxy group, and the phenyl group is more preferably directly bonded to a silicon atom. When silicone having a phenyl group is used, solubility in a solvent (particularly a weak solvent described later) is further increased. As a result, since the viscosity of the paint can be lowered appropriately, workability can be further improved. Moreover, since the refractive index of a coating film improves, initial glossiness improves. Furthermore, a silicone having an alkyl group is preferable, and the alkyl group is more preferably directly bonded to a silicon atom. A silicone having a phenyl group directly bonded to a silicon atom and a propyl group (n-propyl group or isopropyl group) bonded directly to the silicon atom is particularly preferable. Thus, a silicone in which a phenyl group and a propyl group are bonded to a silicon atom may be referred to as “phenylpropyl silicone”, and the phenylpropyl group is not bonded to a silicon atom. Similarly, “phenylmethyl silicone” exists, but the phenylmethyl group is not bonded to a silicon atom. It means a silicone in which a phenyl group and a methyl group are bonded to a silicon atom.

The molecular weight of silicone (b) is not particularly limited. In the present invention, a silicone having a number average molecular weight of preferably 200 to 5,500, more preferably a silicone having a number average molecular weight of 1,400 to 3,000 is used.
Typical examples of such commercially available silicones are 3037 INTERMEDIATE, 3074 INTERMEDIATE, Z-6018, 217 FLAKE, 220 FLAKE, 233 FLAKE, 249 FLAKE, QP8-5314, SR2402, AY 42-163 (all of which are Toray Manufactured by Dow Corning); TSR160, TSR165, TSR3168 (all manufactured by Momentive Performance Materials); KR-211, KR-216, KR-213, KR-9218 (all manufactured by Shin-Etsu Chemical Co., Ltd.) SILRES SY 231, SILRES SY 300, SILRES SY 409, SILRES IC368 (all manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) and the like.

(Oxidation-curable alkyd-modified silicone acrylic copolymer)
The copolymer of the present invention is characterized in that alkyd resin (c), styrenes (a-1) and silicone (b) are polymerized at a specific ratio. That is, with respect to the total amount of alkyd resin (c), styrenes (a-1), (meth) acrylic acid ester (a-2), polymerizable unsaturated monomer (a-3), and silicone (b) The alkyd resin (c) is contained in an amount of 8 to 40% by mass, the styrene (a-1) is contained in an amount of 10 to 30% by mass, and the silicone (b) is contained in an amount of 5 to 15% by mass.

When the content of the alkyd resin (c) is less than 8% by mass, the solvent resistance of the obtained coating film is lowered because the number of oxidatively polymerizable sites is reduced, and the weather resistance of the coating film, initial drying property, and the meat of the coating film The feeling of holding will be poor. On the other hand, when the content of the alkyd resin (c) exceeds 40% by mass, it tends to gel during the production of the copolymer, and even if it does not gel, a coating film using such a copolymer. The water resistance, alkali resistance, weather resistance and the like are reduced. The alkyd resin (c) is preferably contained in a proportion of 15 to 25% by mass.

When the content of styrenes (a-1) is less than 10% by mass, the initial gloss and initial drying properties of the coating film are lowered. On the other hand, when the content of styrenes (a-1) exceeds 30% by mass, the impact resistance (strength) of the coating film becomes poor, and the weather resistance is greatly lowered. The styrenes (a-1) are preferably contained in a proportion of 15 to 25% by mass.

When the content of silicone (b) is less than 5% by mass, the weather resistance of the coating film is greatly reduced. On the other hand, when content of silicone (b) exceeds 15 mass%, it exists in the tendency to gelatinize during manufacture of a copolymer. Even if it does not gel, a coating film using such a copolymer is poor in impact resistance (strength) of the coating film and feeling of flesh of the coating film. Silicone (b) is preferably contained in a proportion of 7 to 12% by mass.

In the copolymer of the present invention, the styrenes (a-1), the (meth) acrylic acid ester (a-2) and the polymerizable unsaturated monomer (a-3) are preferably 45 to 87% by mass in total, More preferably, it is contained in a proportion of 63 to 78% by mass.

The copolymer of the present invention preferably has a solid iodine value of 5 to 50. When the solid iodine value is within such a range, the obtained coating film has good water resistance and alkali resistance in addition to weather resistance, and good strength and fleshiness. Furthermore, gelation is less likely during production of the copolymer, and the solubility in weak solvents is less likely to decrease. The copolymer of the present invention has a solid iodine value of more preferably 18 to 46, still more preferably 20 to 40. The solid iodine value can be measured in accordance with JIS K0070 (Test method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products).

Furthermore, the weight average molecular weight of the copolymer of the present invention is not particularly limited. The copolymer of the present invention preferably has a weight average molecular weight of 10,000 to 150,000. When the weight average molecular weight is in such a range, the resulting coating film has good water resistance and alkali resistance in addition to weather resistance, and more initial gloss can be obtained. Furthermore, the viscosity of the paint does not become too high, and the workability during coating becomes better. The copolymer of the present invention has a weight average molecular weight of more preferably 30,000 to 100,000, still more preferably 40,000 to 80,000. The weight average molecular weight is measured by, for example, gel permeation chromatography (GPC).

(Method for producing oxidation-curing alkyd-modified silicone acrylic copolymer)
The copolymer of the present invention can be obtained, for example, by reacting the above-mentioned oxidatively curable acrylic copolymer (a) with silicone (b). That is, a functional group (at least one selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group) present in the oxidation-curable acrylic copolymer (a) and a hydroxyl group present in the silicone (b) Or an alkoxy group couple | bonds by dehydration or dealcohol condensation, and the oxidation hardening type alkyd modified silicone acrylic copolymer of this invention is obtained.

The dehydration or dealcoholization condensation reaction between the oxidation curable acrylic copolymer (a) and the silicone (b) is performed by, for example, mixing the oxidation curable acrylic copolymer (a) and the silicone (b) to 130 to 180. The reaction is carried out for 2 to 8 hours while heating to 0 ° C. and removing water or alcohol produced. Furthermore, you may react in presence of a well-known catalyst and a reflux solvent as needed. The weather resistance of the coating film can be improved by subjecting the oxidation-curable acrylic copolymer (a) and the silicone (b) to dehydration or dealcoholization condensation reaction. On the other hand, the weather resistance of the coating film becomes insufficient by simply mixing (cold blend) without reacting the oxidation-curable acrylic copolymer (a) and the silicone (b).

In each step of producing the alkyd resin (c), the oxidation-curing acrylic copolymer (a), or the copolymer of the present invention, an organic solvent can be used as necessary. Usable organic solvents include, for example, mineral spirit (also known as mineral terpene, white spirit), isoparaffin, hexane, heptane, octane, nonane, decane, cyclohexane, cycloheptane, toluene, xylene, ethyl acetate, butyl acetate, methanol, Examples include ethanol, butanol, propanol, methyl ethyl ketone, and methyl isobutyl ketone. These solvents may be used alone or in combination of two or more.

In consideration of the environment and the health of the painter, it is preferable to use a weak solvent. A weak solvent is an aliphatic hydrocarbon solvent that may contain a high-boiling aromatic hydrocarbon solvent, and has a high flash point, a high boiling point, and a low hazard, such as terpenes and mineral spirits. Say something. Examples of the mixed solvent include mineral spirit, white spirit, mineral terpene, isoparaffin, solvent kerosene, aromatic naphtha, VM & P naphtha, and solvent naphtha. Other single component solvents include, for example, aliphatic hydrocarbons such as n-butane, n-hexane, n-heptane, n-octane, isononane, n-decane, n-dodecane, cyclopentane, cyclohexane, cyclobutane, etc. Is mentioned.

The copolymer of the present invention thus obtained contains alkyd resin (c), styrenes (a-1) and silicone (b) in a predetermined ratio, and this is used as a film-forming component. When used, a coating film having high initial gloss and satisfactory weather resistance, initial drying property and impact resistance (strength) can be obtained. Therefore, the copolymer of the present invention is suitably used as various coating compositions (for example, for building (indoor and outdoor coating), for automobiles, for baking, etc.) and as coating film forming components and binders in ink compositions. Is done. The above-mentioned coating composition is prepared by mixing the copolymer of the present invention with a solvent, a pigment, a dryer, and, if necessary, other additives (leveling agent, sagging inhibitor, etc.) depending on the application. The

As the solvent, the same alkyd resin (c), oxidatively curable acrylic copolymer (a), or those similar to those used in the respective steps for producing the copolymer of the present invention can be used. . Examples of the pigment include inorganic pigments such as titanium dioxide, carbon black, calcium oxide, barium sulfate, silica, clay, talc, and silica sand, and organic pigments such as phthalocyanine blue. Examples of the dryer include cobalt salt, manganese salt, lead salt, zirconium salt, calcium salt of naphthenic acid or octylic acid.

The copolymer of the present invention is contained in the coating composition in an amount of about 10 to 90% by mass, preferably about 40 to 70% by mass. The obtained coating composition can be used as a room temperature curable coating composition, a baking type coating composition, and the like.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples.

(Synthesis example: Synthesis of alkyd resin)
The following raw materials were charged in a reaction vessel, heated to 240 ° C., and reacted until the acid value became 5 or less while removing water in the reaction system with a water separator. When the acid value became 5 or less, xylene was removed by vacuum distillation. After cooling, the reaction product obtained was diluted with 350 parts by mass of mineral spirit, oil length 50%, acid value 2.5, viscosity (Gardner bubble viscometer / 25 ° C.) Z, color number (Gardner) 6, non-volatile content 60 mass% alkyd resin was obtained.
Phthalic anhydride: 140 parts by weight Dehydrated castor oil fatty acid: 260 parts by weight Glycerin: 50 parts by weight Pentaerythritol: 70 parts by weight Refluxing solvent (xylene): 15.6 parts by weight

Example 1
<Synthesis of oxidation-curable alkyd-modified silicone acrylic resin (copolymer)>
17.53 parts by mass of the alkyd resin (nonvolatile content: 60% by mass) obtained in the above synthesis example and 31.78 parts by mass of mineral spirit were charged into a reaction vessel, and the temperature was raised to 120 ° C. while stirring with aeration of nitrogen gas. . Next, the mixture shown below was dropped into the reaction vessel over 2 hours while maintaining 120 ° C. In addition, the ratio in a parenthesis shows the ratio of each monomer when the total amount of monomers is 100 mass%.
(blend)
I-Butyl methacrylate: 21.24 parts by mass (50.0% by mass)
T-butyl methacrylate: 2.12 parts by mass (5.0% by mass)
N-butyl acrylate: 7.95 parts by mass (18.7% by mass)
Styrene: 10.70 parts by mass (25.2% by mass)
2-hydroxyethyl methacrylate: 0.43 parts by mass (1.0% by mass)
Methacrylic acid: 0.04 parts by mass (0.1% by mass)
t-Hexylperoxyisopropyl monocarbonate: 0.46 parts by mass

After completion of dropping, the mixture was aged at 120 ° C. for 4 hours, and then a water separator was attached to the reaction vessel. 3.96 parts by mass of silicone resin Z-6018 (solid resin having a nonvolatile content of 100% by mass, a number average molecular weight of 2,000 and having a phenyl group and a propyl group directly bonded to a silicon atom, Toray Dow Corning Co., Ltd. )) Was added to the reaction vessel, the temperature was raised to 160 ° C., and the reaction was carried out for 4 hours while removing water in the reaction system with a water separator. After the reaction, the reaction mixture is cooled to 80 ° C. and 3.79 parts by mass of mineral spirit is added to the reaction vessel, and a brown transparent and viscous oxidative curable alkyd-modified silicone acrylic copolymer (resin) (nonvolatile content 55% by mass) is added. Obtained.

The weight average molecular weight of the obtained resin was measured by gel permeation chromatography (GPC). The resin was dissolved in tetrahydrofuran (concentration: 1.0 g / L) and measured by GPC equipped with a differential refractive index detector (RID) to obtain a molecular weight distribution of the resin. Thereafter, the weight average molecular weight (Mw) of the resin was calculated from the obtained chromatogram (chart) using standard polystyrene as a calibration curve. The weight average molecular weight of the obtained resin was 44,000. Measuring devices and measuring conditions are as follows.
Data processor: HLC-8220GPC (manufactured by Tosoh Corporation)
Differential refractive index detector: RI detector built in HLC-8220GPC Column: 2 TSKgel SuperHZM-H (manufactured by Tosoh Corporation) Mobile phase: Tetrahydrofuran Column flow rate: 0.35 mL / min Sample concentration: 1.0 g / L
Injection volume: 10 μL
Measurement temperature: 40 ° C
Molecular weight marker: Standard polystyrene (standard material manufactured by POLYMER LABORATORIES) (using POLYSYRENE-MEDIAUM WEIGHT CALIBRATION KIT)

The solid iodine value of the obtained resin was measured in accordance with JIS K0070 (Testing method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products).

<Preparation of coating composition>
57.0 parts by mass of the obtained resin (nonvolatile content 55% by mass), 23.5 parts by mass of mineral spirit as a solvent, and 14.0 parts by mass of titanium oxide JR-603 (manufactured by Teika) as a pigment, 3.5 parts by mass of a dryer composed of cobalt octylate and zirconium octylate, 2.0 parts by mass of an anti-sagging agent as an additive, kneaded by a three roll mill, coating composition (room temperature curable coating composition) Was prepared.

(Examples 2 to 18 and Comparative Examples 1 to 8)
An oxidatively curable alkyd-modified silicone acrylic copolymer was obtained in the same procedure as in Example 1 except that the components shown in Table 1 were used in the proportions shown in Table 1. A coating composition was prepared in the same manner as in Example 1 except that each of the obtained resins was used. In addition, the symbol shown in Table 1 shows the following compound. Furthermore, the meanings of “phenylpropyl” and “phenylmethyl” of silicone are as described above.
i-BMA: i-butyl methacrylate t-BMA: t-butyl methacrylate n-BA: n-butyl acrylate St: styrene 2-HEMA: 2-hydroxyethyl methacrylate MA: methacrylic acid

(Evaluation)
Using the coating compositions obtained in Examples 1 to 18 and Comparative Examples 1 to 8, (1) initial gloss, (2) initial drying, (3) accelerated weather resistance, and (4) impact resistance evaluated. The results are shown in Table 2. If any one of the physical properties (1) to (4) failed (C evaluation), it was judged that the practicality as a coating composition was lacking.

(1) Initial gloss The obtained coating composition (room temperature curable coating composition) is coated on a 3 mm thick glass plate (150 mm × 70 mm) using a film applicator AP250 (manufactured by Dazai Equipment Co., Ltd.). did. The coated glass plate was dried in a room at 23 ° C. and 50% RH for 1 week, measured for 20 ° specular reflectance (20 ° G), and the measured value was converted to specular gloss according to JIS Z8741. The evaluation was based on the following criteria, and a B rating or higher (mirror reflectivity of 80 or higher) was determined to be acceptable.
A: When the specular gloss is 90 or more A: When the specular gloss is 85 or more and less than 90 B: When the specular gloss is 80 or more and less than 85 C: When the specular gloss is less than 80

(2) Initial drying property The test was performed by a method in which JIS K 5600-3-6 (non-adhesive drying property test) was partially changed. Obtained coating composition (room temperature curable coating composition), weight (500 g, bottom diameter 40 mm), tin plate of thickness 0.3 mm (300 mm × 70 mm), coating tool (film applicator AP250), and pharmacopoeia Gauze (what was normally sold at a pharmacy was cut into 50 mm squares and used) was allowed to stand in an atmosphere of 23 ° C. for 24 hours. Subsequently, the obtained coating composition (room temperature curable coating composition) was coated on a tin plate using a film applicator AP250. The painted tin plate was left in a room at 23 ° C. and 50% RH for 2 hours to place gauze on the surface of the coating film, and a weight was placed thereon. After 1 hour, the weight was taken and the state when the gauze was turned over was evaluated according to the following criteria, and the B evaluation or higher was regarded as acceptable.
A +: When gauze peels off without resistance, and no trace remains on the coating film surface A: When trace remains on the coating film surface, but gauze peels off without resistance B: When gauze is peeled off, resistance is When there is C: When the groundwork (tinplate) is visible when the gauze is peeled off

(3) Accelerated weather resistance The obtained coating composition (room temperature curable coating composition) was coated on a dull steel plate (150 mm × 70 mm) having a thickness of 0.8 mm using a film applicator AP250. Gloss retention (20 °) when painted dull steel plate is dried for one week in a room at 23 ° C and 50% RH and exposed for 1,500 hours with a sunshine weather meter (Suga Test Instruments Co., Ltd.) GR) was determined and evaluated according to the following criteria. A B rating or higher (gloss retention of 70% or higher) was considered acceptable. The gloss retention rate is obtained by the following formula.
Gloss retention (%) = (Specular reflectance after test / Specular reflectance before test) × 100
A: When gloss retention is 90% or more A: When gloss retention is 80% or more and less than 90% B: When gloss retention is 70% or more and less than 80% C: When gloss retention is less than 70%

(4) Impact resistance In accordance with JIS K 5600-5-3 (weight drop resistance test), an impact resistance test was conducted and evaluated according to the following criteria. A B rating or higher was considered acceptable.
A: When the coating film was not broken by impact of 1 kg × 15 cm B: When the coating film was not broken by impact of 1 kg × 10 cm, but when the coating film was broken by impact of 1 kg × 15 cm C: 1 kg × 10 cm When the coating cracks due to impact

As shown in Table 2, in Examples 1 to 18, when the obtained resin was used as a coating film forming component, the obtained coating film had a high initial gloss, initial drying property, weather resistance and resistance. It turns out that it is excellent also in impact property (strength).

On the other hand, in Comparative Examples 1 to 8 in which the content of the alkyd resin (c), styrenes (a-1) or silicone (b) is outside the scope of the present invention, the initial gloss, initial drying property, weather resistance, and resistance It is inferior to any of impact properties (that is, initial gloss is C rating (specular gloss is less than 80), initial drying property is C rating, weather resistance is C rating (gloss retention is less than 70%), or It can be seen that the impact property is C evaluation.

(Comparative Example 9)
<Synthesis of silicone-modified acrylic copolymer>
The reaction vessel was charged with 100 parts by mass of mineral spirits and heated to 115 ° C. with stirring while aeration of nitrogen gas. Subsequently, the following mixture was added dropwise over 4 hours while maintaining the temperature at 115 ° C.
(blend)
N-butyl methacrylate: 15 parts by mass i-butyl methacrylate: 20 parts by mass Styrene: 25 parts by mass 2-ethylhexyl acrylate: 20 parts by mass Glycidyl methacrylate: 20 parts by mass 2,2′-azobisisobutyronitrile : 1 part by mass

After completion of the dropwise addition, the mixture was aged at 115 ° C. for 2 hours, heated to 140 ° C., and 30 parts by mass of linseed oil fatty acid and 0.4 part by mass of N, N-dimethylaminoethanol as a reaction catalyst were added. The fatty acid addition reaction was carried out at 160 ° C. for 5 hours. The resin acid value was traced by the KOH titration method, and the time when the resin acid value became 1.0 or less was taken as the end point. After completion of the reaction, 45 parts by mass of xylene was added for dilution to obtain a brown transparent and viscous fatty acid-modified copolymer solution having a nonvolatile content of 47% by mass. Next, it cooled to 100 degreeC and attached the water separator to the reaction container. In a reaction vessel, 15 parts by mass of Z-6018 (silicone manufactured by Toray Dow Corning Silicone Co., Ltd.), 14 parts by mass of mineral spirit, 6 parts by mass of xylene, and 0.20 mass of tetra-n-butyl titanate as a reaction catalyst. Part was added. The temperature was raised to 165 ° C., and the reaction was allowed to proceed for 5 hours while separating water with a water separator in a reflux system to obtain a brown transparent and viscous silicone-modified acrylic copolymer having a nonvolatile content of 47% by mass.

The ratio of styrene in the raw material of the silicone-modified acrylic copolymer (in solid conversion) is 17.2% by mass, and the ratio of silicone is 10.3% by mass. The weight average molecular weight and solid iodine value of the obtained resin were measured in the same procedure as in Example 1. The weight average molecular weight was 40,000, and the solid iodine value was 28. Using the obtained resin, a coating composition was prepared in the same manner as in Example 1, except that the amount of mineral spirit was adjusted so that the nonvolatile content was the same as in Example 1. Using the obtained coating composition, the above-mentioned (1) initial gloss, (2) initial drying property, (3) accelerated weather resistance, and (4) impact resistance were evaluated. The results are shown in Table 3.

(Comparative Example 10)
<Synthesis of alkyd resin>
The following raw materials were charged into a reaction vessel, heated to 240 ° C., and reacted until the acid value became 8 or less while removing water in the reaction system with a water separator. When the acid value became 8 or less, xylene was removed by vacuum distillation. After cooling, the reaction product obtained was diluted with 350 parts by mass of mineral spirits, oil length 50%, acid value 5.5, viscosity (Gardner bubble viscometer / 25 ° C) Z, color number (Gardner) 6, non-volatile content 58 mass% alkyd resin was obtained.
Phthalic anhydride: 140 parts by weight Dehydrated castor oil fatty acid: 260 parts by weight Glycerin: 50 parts by weight Pentaerythritol: 70 parts by weight Refluxing solvent (xylene): 15.6 parts by weight

In Comparative Example 9, an attempt was made to cause the reaction using 30 parts by mass of the alkyd resin obtained above instead of 30 parts by mass of linseed oil fatty acid. However, since the reaction did not proceed (resin acid value did not decrease), the reaction was stopped and no evaluation was performed.

(Comparative Example 11)
The coating composition was evaluated using a resin in which the monomers shown in (a-1) to (a-3) such as styrenes were not graft-polymerized as the alkyd resin.
<Synthesis of acrylic resin (copolymer)>
The reaction vessel was charged with 42.41 parts by mass of mineral spirits and heated to 118 ° C. with stirring while aeration of nitrogen gas. Subsequently, the following mixture was added dropwise over 3 hours while maintaining the temperature at 118 ° C. In addition, the ratio in a parenthesis shows the ratio of each monomer when the total amount of monomers is 100 mass%.
(blend)
I-Butyl methacrylate: 28.51 parts by mass (50.0% by mass)
T-butyl methacrylate: 2.85 parts by mass (5.0% by mass)
N-butyl acrylate: 10.67 parts by mass (18.7% by mass)
Styrene: 14.36 parts by mass (25.2% by mass)
2-hydroxyethyl methacrylate: 0.57 parts by mass (1.0% by mass)
Methacrylic acid: 0.05 parts by mass (0.1% by mass)
t-Hexylperoxyisopropyl monocarbonate: 0.58 parts by mass

After completion of dropping, the mixture was aged at 120 ° C. for 4 hours and then cooled to 80 ° C. to obtain a brown transparent and viscous acrylic copolymer having a nonvolatile content of 57% by mass.

<Reaction of alkyd resin, copolymer and silicone resin>
In a reaction vessel equipped with a water separator, 17.60 parts by mass of the alkyd resin (nonvolatile content 60% by mass) used in Example 1 above, 74.81 parts by mass of the acrylic copolymer (nonvolatile content 57% by mass), 3.98 parts by mass of silicone resin (Z-6018) used in Example 1 and 7.58 parts by mass of mineral spirit were charged. Next, the mixture was stirred at 120 ° C. for 4 hours while ventilating nitrogen gas to obtain a resin (nonvolatile content: 55% by mass). The proportion of styrene constituting the obtained resin was 18.8 mass% in terms of solid content, the proportion of alkyd resin was 18.5 mass%, and the proportion of silicone was 7.0 mass%. The weight average molecular weight and solid iodine value of the obtained resin were measured in the same procedure as in Example 1. The weight average molecular weight was 47,000, and the solid iodine value was 21.

Using the obtained resin, a coating composition was prepared in the same manner as in Example 1. Using the obtained coating composition, the above-mentioned (1) initial gloss, (2) initial drying property, (3) accelerated weather resistance, and (4) impact resistance were evaluated. The results are shown in Table 3.

(Comparative Example 12)
The coating composition was evaluated using a mixture obtained by simply mixing (cold blend) without reacting the oxidation-curable acrylic copolymer (a) and the silicone (b). First, the reaction vessel was charged with 17.53 parts by mass of alkyd resin (nonvolatile content 60% by mass) and 31.78 parts by mass of mineral spirit used in Example 1 above. Next, the mixture was stirred and heated up to 120 ° C. while bubbling nitrogen gas. While maintaining the temperature at 120 ° C., the following mixture was added dropwise over 2 hours. In addition, the ratio in a parenthesis shows the ratio of each monomer when the total amount of monomers is 100 mass%.
(blend)
I-Butyl methacrylate: 21.24 parts by mass (50.0% by mass)
T-butyl methacrylate: 2.12 parts by mass (5.0% by mass)
N-butyl acrylate: 7.95 parts by mass (18.7% by mass)
Styrene: 10.70 parts by mass (25.2% by mass)
2-hydroxyethyl methacrylate: 0.43 parts by mass (1.0% by mass)
Methacrylic acid: 0.04 parts by mass (0.1% by mass)
t-Hexylperoxyisopropyl monocarbonate: 0.46 parts by mass

After completion of the reaction, the mixture was aged at 120 ° C. for 4 hours to obtain an oxidatively curable acrylic copolymer (a monomer graft polymer to an alkyd resin). Next, a water separator was attached to the reaction vessel and cooled to 80 ° C. The silicone resin (Z-6018) used in Example 1 was charged and stirred at 80 ° C. for 2 hours. During this time, no water was generated in the reaction system. 3.79 parts by mass of mineral spirit was charged into a reaction vessel to obtain a mixture of a brown transparent and viscous oxidative curable acrylic copolymer (a monomer graft polymer to an alkyd resin) and silicone. The proportion of styrene in the obtained mixture was 18.7 mass% in terms of solid content, the proportion of alkyd resin was 18.6 mass%, and the proportion of silicone was 7.0 mass%. The weight average molecular weight and solid iodine value of the obtained mixture were measured by the same procedure as in Example 1. The weight average molecular weight was 40,000, and the solid iodine value was 22.

Using the resulting mixture, a coating composition was prepared in the same manner as in Example 1. Using the obtained coating composition, the above-mentioned (1) initial gloss, (2) initial drying property, (3) accelerated weather resistance, and (4) impact resistance were evaluated. The results are shown in Table 3.

As shown in Table 3, Comparative Example 9 containing no alkyd resin is inferior in initial gloss. Comparative Example 10 is an example in which an alkyd resin was used instead of the unsaturated fatty acid (linseed oil fatty acid) of Comparative Example 9, but the reaction between the epoxy group-containing vinyl copolymer and the alkyd resin did not proceed, and the resin was It was not obtained. Comparative Example 11 is an example in which a resin in which the monomers shown in (a-1) to (a-3) such as styrene are not graft-polymerized is used for the alkyd resin, but the crosslinking reaction during the coating film formation proceeds. It can be seen that the initial gloss, initial drying, weather resistance and impact resistance are all inferior. Comparative Example 12 is an example using a mixture obtained by simply mixing (cold blend) without reacting the oxidation-curable acrylic copolymer and silicone, but it is found that the weather resistance is poor. This is presumably because the silicone does not react with the oxidatively curable acrylic copolymer, and the silicone bleeds out over time.

Claims (7)

1. Oxidation-curable acrylic copolymer (a) obtained by graft polymerization of the following monomers (a-1), (a-2) and (a-3) to alkyd resin (c) having an oxidatively polymerizable group (a) ) And a silicone (b) having at least one of a hydroxyl group and an alkoxy group, and an oxidatively curable alkyd-modified silicone acrylic copolymer,
   In the raw material, the total amount of alkyd resin (c), styrenes (a-1), (meth) acrylic acid ester (a-2), polymerizable unsaturated monomer (a-3), and silicone (b) In contrast, the alkyd resin (c) is contained in an amount of 8 to 40% by mass, the styrenes (a-1) in an amount of 10 to 30% by mass, and the silicone (b) in an amount of 5 to 15% by mass. , Oxidation-curable alkyd-modified silicone acrylic copolymer.
   (A-1) Styrenes (a-2) (Meth) acrylic acid ester (a-3) Polymerization having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group Unsaturated monomers
2. The styrenes (a-1), the (meth) acrylic acid ester (a-2), and the polymerizable unsaturated monomer (a-3) are styrenes (a-1) and (meth) acrylic acid esters. The oxidatively curable alkyd-modified silicone acrylic copolymer according to claim 1, which is contained in the following proportions relative to the total amount of (a-2) and the polymerizable unsaturated monomer (a-3).
   (A-1) Styrenes: 13 to 40% by mass
   (A-2) (Meth) acrylic acid ester: 53 to 86% by mass
   (A-3) Polymerizable unsaturated monomer: 1 to 7% by mass
3. The styrenes (a-1), the (meth) acrylic acid ester (a-2), and the polymerizable unsaturated monomer (a-3) are combined in an oxidatively curable alkyd-modified silicone acrylic copolymer. The oxidatively curable alkyd-modified silicone acrylic copolymer according to claim 1 or 2, which is contained in an amount of 45 to 87% by mass.
4. The oxidatively curable alkyd-modified silicone acrylic copolymer according to any one of claims 1 to 3, having a solid iodine value of 5 to 50.
5. The oxidatively curable alkyd-modified silicone acrylic copolymer according to any one of claims 1 to 4, having a weight average molecular weight of 10,000 to 150,000.
6. The oxidation-curable alkyd-modified silicone acrylic copolymer according to any one of claims 1 to 5, wherein the silicone (b) further has a phenyl group.
7. Oxidation-curable acrylic copolymer (a) obtained by graft polymerization of the following monomers (a-1), (a-2) and (a-3) to alkyd resin (c) having an oxidatively polymerizable group Obtaining
   A step of reacting the obtained oxidatively curable acrylic copolymer (a) with silicone (b) having at least one of a hydroxyl group and an alkoxy group,
   Alkyd relative to the total amount of alkyd resin (c), styrenes (a-1), (meth) acrylic acid ester (a-2), polymerizable unsaturated monomer (a-3), and silicone (b) Oxidation-curing type, characterized in that the resin (c) is used in a proportion of 8 to 40% by mass, the styrene (a-1) is used in a proportion of 10 to 30% by mass, and the silicone (b) is used in a proportion of 5 to 15% by mass. A method for producing an alkyd-modified silicone acrylic copolymer.
   (A-1) Styrenes (a-2) (Meth) acrylic acid ester (a-3) Polymerization having at least one functional group selected from the group consisting of a hydroxyl group, a carboxyl group, a glycidyl group, and an isocyanate group Unsaturated monomers.