JP7049152B2 - Epoxy resin composition for paints - Google Patents

Description

The present invention relates to an epoxy resin composition for paints having a low viscosity and excellent hardness, impact resistance and heat impact resistance.

Epoxy resin compositions that are cured with phenalkamine have been used for many years as primer paints for ships and general structures because they have excellent mechanical properties, water resistance, and chemical resistance. However, in recent years, higher characteristics have been required, and for example, in order to prevent cracks caused by temperature changes and cracks caused by collision between the transported object and the coating film, improvement in thermal shock resistance and impact resistance is required. There is.

As a method for reducing cracks, a method of adding various rubber components to an epoxy resin as a modifier is known. Examples of the rubber component include reactive liquid rubber such as butadiene / acrylonitrile liquid rubber (CTBN) having a terminal carboxylic acid, nitrile rubber (for example, Patent Document 1), core shell rubber (for example, Patent Document 2), and polyether polyol (for example). Examples thereof include Patent Document 3) or a combination thereof (for example, Patent Document 4).

The above method surely shows a high toughening effect in a composition not filled with a filler, but the toughening effect may be small or not seen in a filler-filled system. Further, in the filler filling system, the viscosity tends to increase with the addition of the rubber component, so that the amount of the rubber component added is also limited. Furthermore, impact resistance and thermal impact resistance are usually not correlated, and it is difficult to improve both characteristics at the same time. Further, since the phenalkamine curing agent has a long-chain hydrocarbon group in the molecule, it is relatively hydrophobic, and depending on the rubber component, its dispersion may be poor and it may be difficult to make it tough. From these facts, it is extremely difficult to maintain the viscosity of the composition low in the epoxy resin composition for paints cured with phenalkamine and improve the heat impact resistance and impact resistance without lowering the hardness of the cured product. It was a difficult task.

U.S. Patent 3208980 U.S. Patent 4778851 U.S. Pat. No. 4,497945 U.S. Patent 2015/0218299

An object of the present invention is to provide an epoxy resin composition for a paint having a low viscosity and having hardness, impact resistance and thermostable impact resistance.

That is, the present invention is as follows.
1) A core-shell polymer (D) containing a polyether polyol (A) having a hydroxyl equivalent of 350 to 1100 g / Eq, an epoxy resin (B), a phenalkamine curing agent (C), and a hydroxyl group of 0.055 to 0.140 mmol / g. An epoxy resin composition for paints containing one or more inorganic fillers (E) selected from the group consisting of barium sulfate, mica, talc, iron oxide, zinc phosphate, and titanium oxide.
When the total amount of (A), (B), (C), (D), and (E) is 100% by weight,
The content of (A) is 0.5 to 5.0% by weight,
The content of (D) is 1.5 to 5.0% by weight,
The content of (E) is 30 to 75% by weight,
It relates to an epoxy resin composition for paints.
2) The epoxy resin composition for paint according to 1), wherein the polyether polyol (A) is at least one selected from the group consisting of polyoxypropylene diol, polyoxypropylene triol, polyoxybutylene diol and polyoxybutylene triol. Regarding.
3) The epoxy resin composition for paint according to any one of 1) or 2), wherein the hydroxyl group equivalent of the polyether polyol (A) is 450 to 900 g / Eq.
4) The epoxy resin composition for paint according to any one of 1) to 3), wherein the core-shell polymer (D) is a core-shell polymer having a number average particle size of 0.01 to 0.6 μm.
5) One or more substances selected from the group in which the core layer of the core-shell polymer (D) consists of a diene-based rubber, a (meth) acrylate-based rubber, an organosiloxane-based rubber, a styrene-based polymer, and a (meth) acrylate-based polymer. The epoxy resin composition for a paint according to any one of 1) to 4) contained.
6) The epoxy resin composition for paint according to any one of 1) to 5), wherein the glass transition temperature of the polymer constituting the shell layer of the core-shell polymer (D) is −40 to 20 ° C.
7) The epoxy resin composition for paint according to any one of 1) to 6), wherein the core-shell polymer (D) has a hydroxyl group content of 0.080 to 0.140 mmol / g.
8) The present invention relates to a cured product of the epoxy resin composition for paint according to any one of 1) to 7).
9) The present invention relates to a cured product of the epoxy resin composition for paint according to 8), which has a pencil hardness of 3H or more.
10) The cured product of the epoxy resin composition for paint according to any one of claims 8 or 9, wherein the coating film thickness is 100 to 500 μm.

The epoxy resin composition for paints of the present invention has a low viscosity, and the cured product thereof is excellent in hardness, impact resistance and heat impact resistance.

The epoxy resin composition for paints of the present invention contains a polyether polyol (A) having a hydroxyl equivalent of 350 to 1100 g / Eq, an epoxy resin (B), a phenylacamine curing agent (C), and a hydroxyl group of 0.055 to 0.140 mmol. It contains the core-shell polymer (D) and the specific inorganic filler (E) containing / g, and the components (A), (D) and (E) have a specific amount. As a result, the highly filled epoxy resin composition cured with phenalkamine can obtain a high degree of impact resistance and heat impact resistance.
Hereinafter, the epoxy resin composition of the present invention will be described in detail.

<Polyether polyol (A)>
The polyether polyol (A) used in the present invention has a plurality of ether bonds in the main chain like polyoxyalkylene diols such as polyoxypropylene diol and polyoxybutylene diol, and has two or more hydroxyl groups in the molecule. It is a compound that has. The polyether polyol (A) is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, bisphenol A and the like. Diols; Triols such as trimethylolethane, trimethylolpropane, glycerin; Tetraols such as diglycerin and pentaerythritol; Sugars such as monosaccharides, oligosaccharides and polysaccharides; Sorbitol; Ammonia, ethylenediamine, urea, monomethyldiethanolamine, A compound obtained by ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc. in the presence of an initiator containing one or more active hydrogens such as amines such as monoethyldiethanolamine. be. Further, it may be a polycondensate synthesized by polycondensation such as ethylene glycol, propylene glycol, 1,4-butanediol and neopentyl glycol. It may be a random or block copolymer obtained by using a plurality of types of components at the time of synthesis.

The polyether polyol (A) is preferably a polyoxyalkylene diol such as a polyoxyethylene diol, a polyoxypropylene diol or a polyoxybutylene diol; trifunctional or higher functional alcohols (eg, trimethylol ethane, trimethylol propane, glycerin). Triols such as; triols such as diglycerin, tetraol such as pentaerythritol), one end of the polyoxyalkylene diol is bonded by an ether bond, and the other end remains as a hydroxy group. Compounds (eg, polyoxypropylene glyceryl ethers, etc.), polyoxyethylene triols, polyoxypropylene triols, and polyoxyalkylene triols such as polyoxy (propylene / ethylene) copolymerized triols are also preferred.

The preferred polyether polyol (A) is a polyol having a polyoxyalkylene unit, and from the viewpoint of impact resistance, polyoxypropylene diol, polyoxypropylene triol, polyoxybutylene diol and polyoxybutylene triol are more preferable. Polyoxypropylene diols and polyoxypropylene triols are particularly preferred from the standpoint of thermal shock resistance and low viscosity and handling. The polyoxypropylene polyol of the present invention contains less than 40% by weight of oxyethylene units in the polyoxypropylene polyol, for example, a polyoxypropylene polyol-ethylene oxide adduct having ethylene oxide added to the end of the polyoxypropylene polyol. And so on. The polyoxybutylene diol also includes those having an oxy-3-methylbutylene unit of less than 40% by weight.

The hydroxyl group equivalent of the polyether polyol (A) is 350 to 1100 g / Eq, preferably 450 to 900 g / Eq. When a polyether polyol having the above hydroxyl value range is used, the impact resistance and the thermostable impact resistance tend to be greatly improved and the influence on the compounding viscosity tends to be small. That is, when the hydroxyl group equivalent is too low or too high, the balance between impact resistance, thermal impact resistance and compounding viscosity tends to be poor.

The content (usage amount) of the polyether polyol (A) is the total amount of the components (A), (B), (C), (D) and (E) from the viewpoint of impact resistance and heat impact resistance. When it is 100% by weight, it is 0.5 to 5.0% by weight, preferably 1.0 to 4.0% by weight. If the content is too small, the impact resistance and the heat impact resistance tend not to be sufficiently exhibited, and if the content is too large, the hardness tends to decrease.

<Epoxy resin (B)>
As the epoxy resin (B) of the present invention, any epoxy resin having two or more epoxy groups in the molecule can be used.

For example, a glycidyl ether type epoxy resin such as bisphenol A diglycidyl ether and bisphenol F diglycidyl ether; a cyclic aliphatic type epoxy resin such as 3,4-epoxycyclohexylmethylcarboxylate and 1,4-cyclohexanedimethanol diglycidyl ether; Linear aliphatic epoxy resin such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polypropylene glycol diglycidyl ether; glycidyl ester type epoxy resin such as hexahydrophthalic acid glycidyl ester, tetra Glycidylaminodiphenylmethane, glycidyl compound of xylenediamine, glycidylamine type epoxy resin such as triglycidylaminophenol, glycidylaniline, polysiloxane type epoxy resin having an epoxy group at the end or side chain of polydimethylsiloxane, or phenol novolac type epoxy resin. , Cresol novolac type epoxy resin, triphenyl glycidyl ether methane, tetraphenyl glycidyl ether methane; brominated phenol novolac type epoxy resin, dicyclopentadiene novolac type epoxy resin, naphthol novolac type epoxy resin and the like. These epoxy resins can be used alone or in combination.

Further, a reactive diluent having one epoxy group in the molecule or a reactive diluent having oxetane in the molecule may be added to the epoxy resin (B). The reactive diluent has the effect of lowering the viscosity of the epoxy resin composition. The reactive diluent is preferably used up to 20 parts by weight with respect to 100 parts by weight of the epoxy resin. If too much reactive diluent is used, the mechanical properties of the cured product will be reduced.

Examples of the reactive diluent having one epoxy group in the molecule include alkyl monoglycidyl ethers such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and alkyl glycidyl ethers having 8 to 14 carbon atoms, phenylglycidyl ether, and nonylphenyl glycidyl. Examples thereof include phenol monoglycidyl ether such as ether. These may be used in combination of 2 or more types.

Among these, an epoxy resin containing 70% by weight or more of bisphenol A diglycidyl ether and / or bisphenol F diglycidyl ether is preferable because the effect of the present invention can be easily obtained.

<Phenalkamine hardener (C)>
Phenalkamine hardeners are usually obtained by the Mannich base reaction of phenolic compounds, aldehyde compounds and amines. Examples of phenolic compounds include cardanol extracted from cashew nut shell liquid, examples of aldehyde compounds include formaldehyde, and examples of amines include ethylenediamine and diethyltriamine.

Phenalkamine hardeners are commercially available. For example, Adar3440, Aradur3441, Aradur3442, Aradur3460, Aradur3462, etc. (all of which are manufactured by Huntsman), NC-541, NC-541LV, NC-558, NC-641, LTE-2001, etc. (all of which are manufactured by Cardolite). ), PPA-7041-LV, PPA-7062, PPA-7088, PPA-7709, PPA-7090, PPA-7108, PPA-7115, etc. (Manufactured by Royce International) can be given as a specific example. In addition to these, each company has a lineup of products, and the ones listed in catalogs can be used. These may be used alone or in combination of two or more.

Further, up to 20% by weight of the phenalkamine curing agent may be replaced with another amine-based curing agent. As the other amine-based curing agent, any one used for curing the epoxy resin can be used without particular limitation. For example, aliphatic amines such as diethylaminopropylamine, hexamethylenediamine, methylpentamethylenediamine, trimethylhexamethylenediamine, guanidine, oleylamine, etc .; mensendiamine, isophoronediamine, norbornandiamine, piperidine, N, N'-dimethylpiperazine. , N-aminoethylpiperazine, 1,2-diaminocyclohexane, bis (4-amino-3-methylcyclohexyl) methane, bis (4-aminocyclohexyl) methane, polycyclohexylpolyamine, 1,8-diazabicyclo [5,4 0] Alicyclic amines such as undecene-7 (DBU); 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane (ATU), morpholin , N-Methylmorpholin, polyoxypropylenediamine, polyoxypropylenetriamine, polyoxyethylenediamine and other amines with ether bonds; hydroxyl group-containing amines such as diethanolamine and triethanolamine; Polyamide amines obtained by reacting polyamines, polyamide amines using polycarboxylic acids other than dimer acid; imidazoles such as 2-ethyl-4-methylimidazole; dicyandiamide; epoxy compounds are reacted with the above amines. Examples thereof include modified amines such as epoxy-modified amines, Michael-added modified amines, and ketimines.
Further, the curing accelerator may be used together with the above-mentioned phenalkamine curing agent (and the above-mentioned other amine-based curing agent). Examples of curing accelerators include tertiary amines such as triethylamine and benzyldimethylamine, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, hydroxyl group-containing aromatic compounds such as nonylphenol and benzyl alcohol, and birds. Organic phosphorus compounds such as phenylphosphine, tri-p-tolylphosphine, triphenyl phosphite, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, tetotaphenylphosphine bromide, tetra-n-butylphosphonium Bromide, quaternary phosphonium salts such as tetra n-butylphosphonium o, o-diethylphosphologithionate, diazabicycloalkenes such as 1,8-diazabicyclo [5.4.0] undecene-7 and its organic acid salts, Organic metal compounds such as zinc octylate, tin octylate and aluminum acetylacetone complex, quaternary ammonium salts such as tetraethylammonium bromide and tetrabutylammonium bromide, boron compounds such as boron trifluoride and triphenylborate, zinc chloride and chloride. Examples thereof include metal halogen compounds such as ferric tin. Furthermore, microcapsule-type latent accelerators, amine salt-type latent curing accelerators, Lewis salts, Bronsted acid salts, etc., in which the surface of a high melting point imidazole compound, dicyandiamide, phosphorus-based, or phosphine-based accelerator is coated with a polymer. A latent curing accelerator typified by a high temperature dissociation type thermal cation polymerization type latent curing accelerator can also be used. These curing accelerators can be used alone or in combination of two or more. When the other amine-based curing agent and the curing accelerator can be used, these are included and regarded as a phenalkamine curing agent (C).

The amount of the phenalkamine curing agent used depends on the chemistry of the curing agent, the epoxy resin composition and the desired properties of the cured product. It is preferable to use the phenalkamine curing agent so that the active hydrogen equivalent of the amine of the phenalkamine curing agent is 0.7 to 1.3 per 1 epoxy group equivalent.

<Core shell polymer (D)>
The core-shell polymer (D) is a particulate polymer having a structure of at least two layers, and contains a hydroxyl group of 0.055 to 0.140 mmol / g, preferably 0.080 to 0.140 mmol / g. If the amount is too small or too large, the heat impact resistance tends to decrease.

The hydroxyl group may be contained in the core layer, but it is preferable to contain the hydroxyl group in the shell layer because it exhibits a good balance of physical properties.

The ratio of the core layer in the core-shell polymer is preferably 70 to 95% by weight, more preferably 80 to 93% by weight, from the viewpoint of mechanical properties. When the ratio of the core layer is small, the viscosity of the epoxy resin composition tends to be high. If the proportion of the core layer is too large, it will be difficult to prepare the core-shell polymer (synthesis itself is possible, but it will be difficult to remove it from the reaction solution in a practical form). The ratio of the core layer in the core-shell polymer can be measured from the absorbance ratio of the spectrum of infrared spectroscopic analysis and the like.

The core-shell polymer (D) preferably has a number average particle size of 0.01 to 0.6 μm, more preferably 0.03 to 0.5 μm, and even more preferably 0.05 to 0.4 μm. An emulsion polymerization method is suitable for obtaining a core-shell polymer (D) having such an average particle size, but if it is too small or too large, economical and industrial production becomes difficult. The number average particle size can be measured using a Microtrack UPA150 (manufactured by Nikkiso Co., Ltd.) or the like.

The core-shell polymer (D) preferably has an insoluble content in methyl ethyl ketone (MEK), and the insoluble content (MEK insoluble content) is preferably 95% by weight or more, more preferably 97% by weight or more. More preferably, 98% by weight or more is more preferable. If it is less than 95% by weight, the viscosity of the epoxy resin composition tends to be high, which makes it difficult to handle. In the present specification, the method for obtaining the MEK insoluble amount of the core-shell polymer (D) is as follows. Approximately 2 g of core-shell polymer powder or film is weighed and immersed in 100 g of MEK at 23 ° C. for 24 hours. Then, the obtained MEK insoluble matter is separated, dried and weighed, and the weight fraction (%) with respect to the weight of the core-shell polymer used for the measurement is calculated as the MEK insoluble matter amount.

The core-shell polymer (D) is preferably a polymer composed of a core layer made of a crosslinked polymer and a shell layer made of a polymer component graft-polymerized thereto. That is, it is preferable that a chemical bond exists between the shell layer and the core layer. Since the shell layer graft-polymerizes the monomers constituting the graft component onto the core component, the shell layer covers a part or the whole of the surface of the core portion.

The core layer is one or more selected from the group consisting of a diene-based rubber, a (meth) acrylate-based rubber, an organosiloxane-based rubber, a styrene-based polymer, and a (meth) acrylate-based polymer. In the present invention, (meth) acrylate means acrylate and / or methacrylate.

The core layer is preferably a rubber-like crosslinked polymer from the viewpoint of toughening the epoxy resin. In order for the core layer to have a rubber-like property, the glass transition temperature of the core layer (hereinafter, may be simply referred to as “Tg”) is preferably 0 ° C. or lower, more preferably −20 ° C. or lower. It is preferably −40 ° C. or lower, and it is particularly preferable that the temperature is −40 ° C. or lower.
The Tg can be measured by, for example, a dynamic viscoelasticity measuring method or a differential scanning calorimetry method.

As the polymer capable of forming the core layer having the properties of rubber, at least one monomer (first monomer) selected from natural rubber, a diene-based monomer (conjugated diene-based monomer) and a (meth) acrylate-based monomer). , 50 to 100% by weight, and 0 to 50% by weight of another copolymerizable vinyl-based monomer (second monomer), polysiloxane rubber, or a combination thereof can be mentioned. .. When obtaining a higher toughening effect, a diene-based rubber using a diene-based monomer is preferable. When a balance of toughness, weather resistance, economy and the like is required, (meth) acrylate rubber (also referred to as acrylic rubber) is preferable. Further, when high toughness at low temperature is to be obtained, the core layer is preferably polysiloxane rubber.

Examples of the monomer (conjugated diene-based monomer) constituting the diene-based rubber used for forming the core layer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, and 2-methyl-1,3. -Butadiene and the like can be mentioned. These diene-based monomers may be used alone or in combination of two or more.

Butadiene rubber using 1,3-butadiene, butadiene-styrene rubber which is a copolymer of 1,3-butadiene and styrene, 1,3-butadiene and butyl acrylate or 2-ethylhexyl acrylate Butadiene-acrylate rubber, which is a copolymer, is preferable, and butadiene rubber is more preferable. Further, butadiene-styrene rubber is more preferable when the transparency of the epoxy resin composition obtained by adjusting the refractive index can be enhanced and a good balance between good appearance and toughness can be obtained. Further, the butadiene-acrylate rubber has good weather resistance because the double bond concentration of butadiene in the rubber is lowered by the introduction of the acrylate, which is preferable when such characteristics are required.

Examples of the monomer constituting the (meth) acrylate-based rubber (also referred to as acrylic rubber) used for forming the core layer include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-. Alkyl (meth) acrylates such as ethylhexyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and behenyl (meth) acrylate; phenoxyethyl (meth) acrylate, benzyl (meth) acrylate. Aromatic ring-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylates, hydroxyalkyl (meth) acrylates such as 4-hydroxybutyl (meth) acrylates; glycidyl (meth) acrylates, glycidylalkyl (meth) acrylates, etc. Glycidyl (meth) acrylates; alkoxyalkyl (meth) acrylates; allylalkyl (meth) acrylates such as allyl (meth) acrylates and allylalkyl (meth) acrylates; monoethylene glycol di (meth) acrylates, triethylene glycols. Examples thereof include polyfunctional (meth) acrylates such as di (meth) acrylate and tetraethylene glycol di (meth) acrylate. These (meth) acrylate-based monomers may be used alone or in combination of two or more. Ethyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable.

Examples of the vinyl-based monomer (second monomer) copolymerizable with the first monomer include vinyl allenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinylcarboxylic acids such as acrylic acid and methacrylic acid. Vinyl cyanes such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride, vinyl bromide and chloroprene; Vinyl acetate; Alkenes such as ethylene, propylene, butylene and isobutylene; Examples thereof include polyfunctional monomers such as triallyl isocyanurate and divinylbenzene. These vinyl-based monomers may be used alone or in combination of two or more. Styrene is particularly preferable.

The organosiloxane-based rubber that can form the core layer is composed of an alkyl or aryl 2-substituted silyloxy unit such as dimethylsiloxane, diethylsiloxane, methylphenylsiloxane, diphenylsiloxane, and dimethylsiloxane-diphenylsiloxane. Examples thereof include an organosiloxane-based polymer composed of an alkyl or aryl 1-substituted siloxane unit, such as an organosiloxane-based polymer in which a part of the alkyl in the side chain is substituted with a hydrogen atom. These organosiloxane-based polymers may be used alone or in combination of two or more. Further, a composite rubber made of (meth) acrylate-based rubber / organosiloxane-based rubber combined with (meth) acrylate-based rubber may be used. Among them, dimethylsiloxane rubber, methylphenylsiloxane rubber, and dimethylsiloxane / butylacrylate composite rubber are preferable in terms of weather resistance and mechanical properties, and dimethylsiloxane rubber and dimethylsiloxane / butylacrylate composite rubber are easily available and economical. Most preferred.

In the embodiment in which the core layer is formed of an organosiloxane-based rubber, the organosiloxane-based polymer moiety contains at least 10% by weight of the entire core layer as 100% by weight so as not to impair the mechanical properties at low temperature. Is preferable.

From the viewpoint of maintaining the dispersion stability of the core-shell polymer (D) in the epoxy resin, the core layer may have a crosslinked structure introduced into a polymer component obtained by polymerizing the monomer or an organosiloxane-based polymer component. preferable. As a method for introducing the crosslinked structure, a generally used method can be adopted. For example, as a method of introducing a crosslinked structure into a polymer component obtained by polymerizing the above-mentioned monomer, a method of adding a crosslinked monomer such as a polyfunctional monomer or a mercapto group-containing compound to the monomer constituting the polymer component and then polymerizing the monomer. And so on. In addition, as a method for introducing a crosslinked structure into an organosiloxane-based polymer, a method in which a part of a polyfunctional alkoxysilane compound is used in combination at the time of polymerization, or a reactive group such as a vinyl-reactive group, a mercapto group, or a methacryloyl group is used as an organo. A method of introducing into a siloxane polymer and then adding a vinyl polymerizable monomer or an organic peroxide to cause a radical reaction, or a crosslinkable monomer such as a polyfunctional monomer or a mercapto group-containing compound is added to the organosiloxane polymer. Examples thereof include a method of adding and then polymerizing.
The polyfunctional monomer does not contain butadiene, and allylalkyl (meth) acrylates such as allyl (meth) acrylate and allylalkyl (meth) acrylate; allyloxyalkyl (meth) acrylates; (poly) ethylene glycol di. It has two or more (meth) acrylic groups such as (meth) acrylate, butanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene glycol di (meth) acrylate. Polyfunctional (meth) acrylates; examples thereof include diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene and the like. Particularly preferred are allyl methacrylate, triallyl isocyanurate, butanediol di (meth) acrylate, and divinylbenzene.

On the other hand, when a good balance between the strength and elastic modulus of the epoxy resin is required, the Tg of the core layer is preferably larger than 0 ° C, more preferably 20 ° C or higher, and more preferably 50 ° C or higher. It is more preferably 80 ° C. or higher, and most preferably 120 ° C. or higher.

As a polymer capable of forming a core layer having a Tg of more than 0 ° C. and not reducing or improving the elasticity of the epoxy resin, at least one monomer having a Tg of a homopolymer above 0 ° C. is 50 to 100. Consists of 0 to 50% by weight (more preferably 1 to 35% by weight) of at least one monomer having a Tg of less than 0 ° C. and 0 to 50% by weight (more preferably 65 to 99% by weight). The polymer to be used is mentioned.

Even when the Tg of the core layer is larger than 0 ° C., it is preferable that the core layer has a crosslinked structure introduced. By introducing the crosslinked structure, Tg is raised. Examples of the method for introducing the crosslinked structure include the above method.

Examples of the monomers having a Tg of more than 0 ° C. in the homopolymer include those containing one or more of the following monomers, but are not limited thereto. For example, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; vinyl-substituted aromatic compounds such as α-methylstyrene; 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2, Ring-alkylated vinyl aromatic compounds such as 5-dimethylstyrene, 3,5-dimethylstyrene, 2,4,6-trimethylstyrene; ring-alkenylated vinyl aromatic compounds such as 4-methoxystyrene and 4-ethoxystyrene. Ring-halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; Ring ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; Ring-hydroxylated vinyl aromatic compounds such as 4-hitoroxystyrene; Classes; vinyl esters such as vinyl benzoate and vinyl cyclohexanoate; vinyl halides such as vinyl chloride; aromatic monomers such as acenaphthalene and inden; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and isopropyl methacrylate; phenyl Aromatic methacrylates such as methacrylate; methacrylates such as isobornyl methacrylate and trimethylsilyl methacrylate; methacrylic monomers containing methacrylic acid derivatives such as methacrylonitrile; certain acrylic acid esters such as isobornyl acrylate and tert-butyl acrylate; Acrylic monomers containing an acrylic acid derivative such as acrylonitrile can be mentioned. Further, monomers such as acrylamide, isopropylacrylamide, N-vinylpyrrolidone, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate and 1-adamantyl methacrylate can be mentioned.

In the present invention, the core layer often has a single-layer structure, but may have a multi-layer structure. When the core layer has a multi-layer structure, the polymer composition of each layer may be different.

That is, a core composed of two layers having a second layer having a different polymer composition on the outside of the first core layer, or a core composed of two layers further formed a third layer having a different polymer composition to form three layers. It may be a core layer made of. When the second layer of the two-layer core or the third layer of the three-layer core is composed of a polymer obtained by polymerizing a polyfunctional monomer such as triallyl isocyanurate described above as a main component, a shell polymer described later is grafted. There is a merit that it becomes easy. However, the formation of a multi-layered core has the disadvantage of complicating the manufacturing process.

The outermost shell layer of the core-shell polymer (D), that is, the shell polymer, controls the compatibility with the polyether polyol (A), the epoxy resin (B), the phenalkamine curing agent (C), and the like, and the core-shell polymer. It plays a role of effectively dispersing.

Such shell polymers are preferably grafted onto the core layer. More precisely, it is preferable that the monomer component used for forming the shell polymer is graft-polymerized on the core polymer forming the core layer, and the shell polymer and the core are substantially chemically bonded. That is, preferably, the shell polymer is formed by graft-polymerizing the shell-forming monomer in the presence of the core polymer, and by doing so, the shell polymer is graft-polymerized on the core polymer, and is one of the core polymers. It covers a part or the whole. This polymerization operation can be carried out by polymerizing the latex of the core polymer prepared and existing in the state of an aqueous polymer latex by adding a monomer which is a constituent component of the shell polymer.

Further, the shell layer forming monomer preferably has a glass transition temperature (also referred to as Tg) of the shell polymer of -40 to 20 ° C., more preferably -40 to 20 ° C., from the viewpoint of obtaining an epoxy resin composition having a good physical balance. It needs to be selected to be −35 to 15 ° C., more preferably −30 to 10 ° C.

The Tg of the polymer obtained from the selected monomer can be obtained from a handbook, technical data obtained from a supplier of various monomers, a handbook, and the like. Aldrich (Reference: Polymer Properties, provided by Aldrich) is easy to use with a relatively large amount of data, but the Tg of polyacrylonitrile is 85 ° C (358K), The Tg of polyallyl methacrylate is 52 ° C (325K) from the technical data of BASF, and the Tg of poly4-hydroxylbutyl acrylate is -40 ° C (233K) from the technical data of Nippon Kasei Co., Ltd., polyglycidyl methacrylate. The Tg of the above is preferably 46 ° C. (319K) from the technical data of SANESTERS CORPORATION. Specifically, the Tg of the copolymer can be calculated using the Tg of the homopolymer. "ENCYCLOPEDIA OF POLYMER SCIENCE AND ENGINEERING" published by John Wiley & Son, 1987, 7 volumes, calculated by the Fox formula described on page 539. That is, the Tgc of the copolymer is a copolymer composed of m kinds of monomers. It was calculated by the following formula (1) from the glass transition temperature Tgn of the homopolymer of each monomer constituting the above and its weight fraction Wfn (value of% by weight / 100). In the same formula, the unit of Tg is. Since the absolute temperature (K) is used, it is converted to the Celsius temperature (° C.) by subtracting 273 from the obtained absolute temperature value.
Formula (1)

For example, the Tg of the copolymer composed of 50% by weight of styrene, 25% by weight of methyl methacrylate and 25% by weight of butyl acrylate is Tg373 (K) (100 ° C.) for polystyrene and Tg378 (K) (105 ° C.) for polymethylmethacrylate. , Tg-54 ° C. (219K) of polybutyl acrylate is substituted into the formula (1) to obtain the value of 318 (K) (45 ° C.).

In order to obtain the features of the present invention such as reduction of compounding viscosity, high impact resistance and thermal impact resistance, it is preferable to use a hydroxyl group-containing vinyl monomer as a part of the monomer for forming a shell layer. As a result, the core-shell polymer can contain a specific amount of hydroxyl groups. As the monomer to be copolymerized with the hydroxyl group-containing vinyl monomer, it is preferable to use a (meth) acrylate monomer or an aromatic vinyl monomer.

Further, when a polyfunctional monomer having two or more double bonds is used as the monomer for forming the shell layer, a crosslinked structure is introduced into the shell layer. As a result, the interaction between the core-shell polymer and the epoxy resin (B) is reduced, and as a result, the viscosity of the epoxy resin composition can be reduced. Therefore, it may be preferable to use a polyfunctional monomer having two or more double bonds. On the other hand, since the elongation of the cured product of the epoxy resin tends to decrease, if it is desired to improve the elongation to the maximum, do not use a polyfunctional monomer having two or more double bonds as the monomer for forming the shell layer. Is preferable.
When used, the polyfunctional monomer is preferably contained in the shell layer forming monomer in an amount of 0.5 to 10% by weight, more preferably 1 to 5% by weight.

Specific examples of the (meth) acrylate monomer include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and octyl (meth). ) Acrylate and the like can be mentioned.

Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, divinylbenzene and the like.

Specific examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

Specific examples of the polyfunctional monomer having two or more double bonds include the same monomers as the above-mentioned polyfunctional monomer, but allyl methacrylate and triallyl isocyanurate are preferable.
The shell layer may be formed by containing other monomer components in addition to the above-mentioned monomer components.

The proportion of the shell layer in the core-shell polymer (D) is 5 to 30% by weight, more preferably 7 to 20% by weight, assuming that the entire core-shell polymer is 100% by weight. If the proportion of the shell layer is too high, the viscosity of the epoxy resin composition tends to be too high. Also, if the amount is too small, it becomes difficult to disperse the core-shell polymer in the epoxy resin.

<< Manufacturing method of core-shell polymer (D) >>
(Manufacturing method of core layer)
The polymer forming the core layer constituting the core-shell polymer (D) used in the present invention is at least one monomer (first monomer) selected from a diene-based monomer (conjugated diene-based monomer) and a (meth) acrylate-based monomer. When configured by including, the formation of the core layer can be produced by, for example, emulsion polymerization, suspension polymerization, microsuspension polymerization, or the like, and for example, the method described in WO2005 / 028546 can be used. ..

When the polymer forming the core layer is composed of an organosiloxane-based polymer, the formation of the core layer can be produced, for example, by emulsion polymerization, suspension polymerization, microsuspension polymerization, or the like. The method described in EP1338625 can be used.

(Method of forming the shell layer)
The shell layer can be formed by polymerizing a monomer for forming a shell layer by a known radical polymerization. When the core layer is obtained as an emulsion of the core-shell polymer (D) precursor, the polymerization of the shell layer-forming monomer is preferably carried out by an emulsion polymerization method, and is produced, for example, according to the method described in WO2005 / 028546. be able to.

Examples of the emulsifier (dispersant) that can be used in emulsifying polymerization include alkyl or aryl sulfonic acid represented by dioctyl sulfosuccinic acid and dodecylbenzene sulfonic acid, alkyl or aryl ether sulfonic acid, and alkyl or aryl represented by dodecyl sulfate. Sulfuric acid, alkyl or aryl ether sulfuric acid, alkyl or aryl substituted phosphoric acid, alkyl or aryl ether substituted phosphoric acid, N-alkyl or aryl zarcosic acid typified by dodecyl sarcosic acid, alkyl represented by oleic acid or stearic acid or Various acids such as arylcarboxylic acids, alkyl or aryl ether carboxylic acids, anionic emulsifiers (dispersants) such as alkali metal or ammonium salts of these acids; nonionic emulsifiers (dispersants) such as alkyl or aryl substituted polyethylene glycols. ); Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives can be mentioned. These emulsifiers (dispersants) may be used alone or in combination of two or more.

It is preferable to use a small amount of the emulsifier (dispersant) as long as the dispersion stability of the aqueous latex of the core-shell polymer (D) is not hindered. The higher the water solubility of the emulsifier (dispersant), the more preferable it is. When the water solubility is high, the emulsifier (dispersant) can be easily removed by washing with water, and adverse effects on the finally obtained polyol composition can be easily prevented.

Thermally decomposed initiators such as 2,2'-azobisisobutyronitrile, organic peroxides, hydrogen peroxide, potassium persulfate, and ammonium persulfate are well known as initiators for the emulsion polymerization method. Organic peroxides are particularly preferred in the present invention.

Preferred organic peroxides include t-butyl peroxyisopropyl carbonate, paramentan hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, di-t-. Hexyl peroxide and the like can be mentioned. Among them, di-t-butyl peroxide (T ₁₀ : 124 ° C) paramentan hydroperoxide (T ₁₀ : 128) having a pyrolysis temperature (hereinafter, also referred to as T ₁₀ ) with a 10-hour half-life of 120 ° C or higher. ℃), cumene hydroperoxide (T ₁₀ : 158 ° C), t-butyl hydroperoxide (T ₁₀ : 167 ° C) and other organic peroxides can be used to reduce the MEK insoluble content of the core-shell polymer (D). It is preferable because it can be increased.

Also, organic peroxides and, if necessary, sodium formaldehyde sulfoxylate, reducing agents such as glucose, and if necessary, transition metal salts such as iron (II) sulfate, and if necessary, ethylenediamine disodium tetraacetate, etc. It is preferable to use a redox-type initiator in which a chelating agent of the above and, if necessary, a phosphorus-containing compound such as sodium pyrophosphate are used in combination.

When the redox-type initiator system is used, the polymerization can be carried out even at a low temperature at which the peroxide does not substantially undergo thermal decomposition, and the polymerization temperature can be set in a wide range, which is preferable.
The amount of the initiator used, and when the redox-type initiator is used, the amount of the reducing agent, transition metal salt, chelating agent, etc. used can be used within a known range.
Chain transfer agents can also be used if desired. The chain transfer agent may be any as long as it is used in ordinary emulsion polymerization, and is not particularly limited.

Specific examples of the chain transfer agent include t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan and the like.
Conditions such as polymerization temperature, pressure, and deoxidation at the time of polymerization can be applied within a known range.

<Inorganic filler (E)>
The inorganic filler (E) used in the present invention has adhesion to the base material and corrosion of the base material, and has impact resistance and heat impact resistance due to the polyether polyol (A) and the core-shell polymer (D). Those that are easily expressed are selected. As a specific example, it is one or more selected from the group consisting of barium sulfate, mica, talc, iron oxide, zinc phosphate, and titanium oxide. Of these, barium sulfate is particularly preferable, and it is preferable that the inorganic filler contains 50% by weight or more. Calcium carbonate, silica powder, and the like are often used as inorganic fillers, but are not preferable in the present invention because the balance of physical properties including corrosion resistance tends to decrease.

The particle size of the inorganic filler (E) is preferably 0.01 to 30 μm, more preferably 0.1 to 15 μm. If it is too small, the viscosity of the epoxy resin composition tends to be high, and if it is too large, the impact resistance tends to decrease.
As for the blending amount of the inorganic filler (E), since impact resistance and heat impact resistance are likely to be exhibited, the total amount of the components (A), (B), (C), (D) and (E) is 100. In terms of% by weight, it is 30 to 75% by weight, preferably 35 to 70% by weight. If the amount is too small or too large, the adhesion of the epoxy resin composition to the substrate tends to decrease, and the impact resistance tends to decrease.

<Other ingredients>
In the present invention, other compounding ingredients can be used as needed. The other compounding components may be used without particular limitation as long as they are used in ordinary epoxy resin compositions. For example, solvents, water, silane coupling agents, defoamers, anti-settling agents, thioxogenic agents, colorants such as pigments and dyes, extender pigments, ultraviolet absorbers, antioxidants, stabilizers (anti-gelling). Agents), plasticizers, leveling agents, antistatic agents, flame retardants, lubricants, thickeners, low shrinkage agents, organic fillers, thermoplastic resins, desiccants, dispersants and the like. Above all, the use of a solvent may be preferable because the solvent greatly lowers the compounding viscosity and enables coating by spraying. Preferred specific examples of the solvent include xylene, n-butanol, methyl ethyl ketone, methyl butyl ketone and the like. When a solvent is used, the amount used is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of the epoxy resin composition of the present invention. Further, water may be used instead of the solvent in order to reduce the environmental load. The amount of water used is preferably 5 to 80 parts by weight, more preferably 20 to 70 parts by weight, based on 100 parts by weight of the epoxy resin composition of the present invention. The silane coupling agent is particularly preferable because it improves the adhesiveness between the filler, the adhesive base material, the glass fiber, the carbon fiber, and the like and the resin. Specific examples thereof include 3-glycidyloxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-aminopropyltrimethoxysilane. The amount used is preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the epoxy resin composition. Further, since it is necessary to reduce air bubbles in the epoxy resin composition as much as possible, it is preferable to add an antifoaming agent during blending. As the defoaming agent, for example, a defoaming agent such as silicone-based, fluorine-based, acrylic-based, polyoxyethylene-based, or polyoxypropylene-based defoaming agent may be appropriately selected. Specific examples include BYK-A500 and BYK-1790 manufactured by Big Chemie. The amount used is preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the epoxy resin composition. Further, when a filler or the like is used in the epoxy resin composition, it is preferable to add a sedimentation inhibitor in order to improve the storage stability thereof. As the sedimentation inhibitor, an additive that enhances the thixotropic property of the epoxy resin composition, for example, fumed silica or fine powdered organic bentonite is preferable. The amount of the anti-settling agent used is preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the epoxy resin composition. Flame retardants include inorganic flame retardants such as aluminum hydroxide and magnesium hydroxide, tetrabromobisphenol A and its variants, halogen-based flame retardants such as tetrabromophthalade, triphenyl phosphate, bisphenol A bis (diphenyl) phosphate and Examples thereof include a phosphorus-based flame retardant such as reactive bisphenol A bis (diphenyl) phosphate, and a silicone-based flame retardant. It is preferable to use 1 to 200 parts by weight of the flame retardant with respect to 100 parts by weight of the epoxy resin (B).

<Manufacturing method of epoxy resin composition>
The epoxy resin composition of the present invention contains a polyether polyol (A) having a hydroxyl group equivalent of 350 to 1100 g / Eq, an epoxy resin (B), a phenalkamine curing agent (C), and a hydroxyl group of 0.055 to 0.140 mmol / g. Epoxy resin composition for paints containing the core-shell polymer (D) and one or more inorganic fillers (E) selected from the group consisting of barium sulfate, mica, talc, iron oxide, zinc phosphate and titanium oxide. And
When the total amount of (A), (B), (C), (D), and (E) is 100% by weight,
The content of (A) is 0.5 to 5.0% by weight,
The content of (D) is 1.5 to 5.0% by weight,
The content of (E) is 30 to 75% by weight,
Is what it is.

In the above formulation, the viscosity of the epoxy resin composition can be obtained by using a dispersion in which the core-shell polymer (D) is once dispersed in the polyether polyol (A) or the epoxy resin (B) in the state of primary particles. It is preferable because it is easy to control. In particular, it is preferable to disperse the core-shell polymer in the polyether polyol (A) because it can be dispersed in a high concentration and the viscosity of the dispersion is lowered.

As a method for obtaining the dispersion in which the core-shell polymer (D) is dispersed in the polyether polyol (A) or the epoxy resin (B) in the state of primary particles, various methods can be used, for example, an aqueous latex state. A method of removing unnecessary components such as water after contacting the core-shell polymer obtained in 1 with the polyether polyol (A) or the epoxy resin (B). The core-shell polymer is once extracted into an organic solvent and then the polyether polyol (A). ) Or a method of removing the organic solvent after mixing with the epoxy resin (B), etc., but it is preferable to use the method described in International Publication WO2005 / 028546. The specific production method is as follows, in order, an aqueous latex containing a core-shell polymer (specifically, a reaction mixture after producing a core-shell polymer by emulsification polymerization) has a solubility in water at 20 ° C. of 5% or more and 40% or less. After mixing with the organic solvent of the above, the first step of further mixing with excess water to aggregate the core-shell polymer, and after separating and recovering the aggregated core-shell polymer from the liquid phase, the core-shell polymer is mixed again with the organic solvent and the core-shell. Prepared including a second step of obtaining an organic solvent solution of the polymer, and a third step of further mixing the organic solvent solution with the polyether polyol (A) or the epoxy resin (B) and then distilling off the organic solvent. Is preferable.

It is preferable that the polyether polyol (A) or the epoxy resin (B) is liquid at 23 ° C. because the third step is facilitated. "Liquid at 23 ° C" means that the softening point is 23 ° C or lower, and shows fluidity at 23 ° C.

Using a composition in which the core-shell polymer is dispersed in the state of primary particles (hereinafter, also referred to as a primary particle dispersion composition) in the polyether polyol (A) or the epoxy resin (B) obtained through the above steps. If necessary, the polyether polyol (A) or the epoxy resin (B) is added, and further, the phenalkamine curing agent (C) and the inorganic filler (E) are additionally mixed, and if necessary, the other compounding components are described above. The epoxy resin composition of the present invention can be obtained by mixing the above.

On the other hand, the powdery core-shell polymer obtained by solidifying by a method such as salting out and then drying is made of poly using a disperser having a high mechanical shearing force such as a three-paint roll, a roll mill, or a kneader. It can be redispersed in the ether polyol (A) or the epoxy resin (B). At this time, by applying a mechanical shearing force to the mixture of the polyether polyol (A) or the epoxy resin (B) and the core-shell polymer at a high temperature, the core-shell polymer is contained in the polyether polyol (A) or the epoxy resin (B). Allows for efficient dispersion. The temperature at the time of dispersion is preferably 50 to 200 ° C, more preferably 70 to 170 ° C, further preferably 80 to 150 ° C, and particularly preferably 90 to 120 ° C. If the temperature is lower than 50 ° C, the core-shell polymer may not be sufficiently dispersed, and if it is higher than 200 ° C, the polyether polyol (A), the epoxy resin (B) and the core-shell polymer (D) are thermally deteriorated. There is.

The epoxy resin composition of the present invention contains a polyether polyol (A), an epoxy resin (B), a phenalkamine curing agent (C), a core-shell polymer (D) and an inorganic filler (E) as main components and a curing component. It may be mixed and prepared as. For example, the main component is a mixed component of a polyether polyol (A), an epoxy resin (B), a core-shell polymer (D), and an inorganic filler (E), a phenalkamine curing agent (C), and an inorganic filler (E) if necessary. ) May be included in the curing component and then mixed to prepare the epoxy resin composition of the present invention. After the curing agent component, the epoxy resin composition of the present invention may be prepared by mixing with a main component consisting of an epoxy resin (B) and an inorganic filler (E). These are examples, and in any combination other than these, the main component and the curing component may be separately mixed.

<Curing product>
The present invention includes a cured product obtained by curing the epoxy resin composition. The epoxy resin composition can be cured under normal epoxy curing conditions: −5 to 150 ° C. for 30 minutes to 10 days. The hardness of the obtained cured product is pencil hardness, preferably 3H or more. The thickness of the coating film obtained by curing is preferably 100 to 500 μm. If it is too thin or too thick, the physical characteristics of the cured product tend to be unbalanced.

<Use>
The cured product obtained from the composition of the present invention has excellent hardness, impact resistance and heat impact resistance, and is therefore suitable for a paint for undercoating and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto, and can be appropriately modified and carried out to the extent that it can meet the purposes of the preceding and the following. And all of them are included in the technical scope of the present invention. In the following Examples and Comparative Examples, "parts" and "%" mean parts by weight or% by weight.

The measurements and tests in the following synthetic examples, examples and comparative examples were performed as follows.

[1] Measurement of Average Particle Size of Polymer Particles The number average particle size (Mn) of the polymer particles dispersed in the aqueous latex was measured using Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). A sample diluted with deionized water was used as a measurement sample.

[2] Measurement of MEK Insoluble Content of Core Shell Polymer 2 g of the core shell polymer obtained by drying from latex was immersed in 100 g of MEK for 24 hours at 23 ° C., and then the MEK insoluble content was centrifuged. The obtained insoluble matter was dried and weighed, and the weight fraction (%) of the MEK insoluble matter with respect to the weight of the core-shell polymer was calculated.

[3] Viscosity measurement The viscosity was measured at 25 ° C. at a shear rate of 5 cycles / sec using a cone plate type viscometer manufactured by BROOKFIELD using a cone plate 3 ° / 24 mm.

[4] Evaluation of Impact Resistance The test was carried out at a test temperature of 23 ° C. according to ASTM D2794. First, the epoxy resin composition for paint was applied to a cold-rolled steel sheet (thickness 0.8 mm) using an applicator, left at room temperature for 3 days or more to cure, and then left at 60 ° C for 3 hours to sufficiently cure. .. The test plate was left at 23 ° C. for 1 day, and then the coating film thickness was measured. Then, a weight weighing 1 kg was dropped on this coating film from different heights, and the height at which cracks were formed was measured. This was taken as the impact resistance index (cm).

[5] Evaluation of heat resistance and impact resistance The epoxy resin composition for paint was placed in a mold set so that a spring washer (size M10) was embedded in the center and cured (curing conditions are the same as in [4]). A heat cycle test was performed in which the obtained diameter of 26 mm and thickness of 5 mm was 60 ° C./30 minutes to -30 ° C./30 minutes as one cycle. The number of cycles when cracks occurred in the cured product was recorded and used as the thermal shock resistance index.

[6] Evaluation of hardness Using the test plate prepared by the method of the above [4], the pencil hardness of the coating film was evaluated at 23 ° C. The evaluation was performed according to ASTM D3363.

The polyether polyol (A), the epoxy resin (B), the phenalkamine-based curing agent (C), the core-shell polymer (D) and the inorganic filler (E) used in Examples and Comparative Examples are shown. The core-shell polymer (D) dispersed in the polyether polyol (A) or the epoxy resin (B) was designated as the dispersion (F).

<Polyether polyol (A)>
A-1: PPD1000, polyoxypropylene diol with a number average molecular weight of 1000 (manufactured by Mitsui Chemicals, Inc., Actol D-1000: hydroxyl group equivalent 510 g / Eq)
A-2: Polyoxypropylene diol with PPD1500 and number average molecular weight 1500 (manufactured by Mitsui Chemicals, Inc., Actol D-1500: hydroxyl group equivalent 748 g / Eq)
A-3: Polyoxypropylene triol with PPT 1500 and number average molecular weight 1500 (manufactured by Mitsui Chemicals, Inc., Actol T-1500: hydroxyl group equivalent 510 g / Eq)
A-4: Polyoxypropylene diol with PPD2000 and number average molecular weight 2000 (manufactured by Mitsui Chemicals, Inc., Actol D-2000: hydroxyl group equivalent 1020 g / Eq)
A-5: PPD700, polyoxypropylene diol with a number average molecular weight of 700 (manufactured by Mitsui Chemicals, Inc., Actol D-700: hydroxyl group equivalent 351 g / Eq)
A-6: PPD400, polyoxypropylene diol with a number average molecular weight of 400 (manufactured by Mitsui Chemicals, Inc., Actol D-400: hydroxyl group equivalent 200 g / Eq)
A-7: Polyoxypropylene diol with PPD2400 and number average molecular weight of 2400 (Mitsui Chemicals, Inc., equal weight mixture of Actol D-2000 and Actol D3000: hydroxyl group equivalent 1200 g / Eq)

<Epoxy resin (B)>
B-1: BPADGE, bisphenol A diglycidyl ether (jER828EL manufactured by Mitsubishi Chemical Corporation)

<Phenalkamine-based curing agent (C)>
C-1: NC-541LV phenalkamine (NC-541LV manufactured by Cardlight).

<Core-shell polymer (D)> See synthetic examples below. D-1 to D-8: Core-shell polymer in which the main component of the core is a butadiene rubber core.

<Inorganic filler (E)>
E-1: Barium sulfate (W-1, manufactured by Takehara Chemical Industry Co., Ltd., average particle size 1.5 μm)
E-2: Talc (Talc manufactured by Wako Pure Chemical Industries, Ltd., average particle size 10 to 15 μm)
E-3: Iron oxide (Laxess Bayferrox 180M, average particle size 1 μm)

<Dispersion (F)> Refer to the synthetic example described later. F-1: Dispersion in which 40% by weight of the core-shell polymer (D-1) is dispersed in the polyether polyol (A-1) F-2: Core-shell polymer (D-) 2) Dispersion F-3 in which 40% by weight is dispersed in the polyether polyol (A-1): Dispersion F-4 in which 40% by weight of the core-shell polymer (D-3) is dispersed in the polyether polyol (A-1). : 40% by weight of core-shell polymer (D-4) dispersed in polyether polyol (A-1) F-5: 40% by weight of core-shell polymer (D-5) dispersed in polyether polyol (A-1) Dispersion F-6: 40% by weight of the core-shell polymer (D-6) dispersed in the polyether polyol (A-1) F-7: 40% by weight of the core-shell polymer (D-7) was a polyether polyol ( Dispersion F-8 dispersed in A-1): 40% by weight of core-shell polymer (D-8) dispersed in polyether polyol (B-1) F-9: 40% by weight of core-shell polymer (D-2) Dispersion F-10 in which% is dispersed in the polyether polyol (A-2): Dispersion in which 40% by weight of the core-shell polymer (D-2) is dispersed in the polyether polyol (A-3) F-111: Core-shell polymer ( D-2) Dispersion F-12 in which 40% by weight is dispersed in the polyether polyol (A-4): Dispersion F in which 40% by weight of the core-shell polymer (D-2) is dispersed in the polyether polyol (A-5). -13: Dispersion in which 40% by weight of the core-shell polymer (D-2) is dispersed in the polyether polyol (A-6) F-14: 40% by weight of the core-shell polymer (D-2) is a polyether polyol (A-7) Dispersion dispersed in

<Other ingredients>
G-1: Thixotropy, organic bentonite (Benton SD-2 manufactured by Elementis)
H-1: Dispersant, U100 (manufactured by BYK, Anti-Terra-U100)
I-1: Solvent mixture, solvent mixture in which xylene (X) and n-butanol (B) are mixed in a weight ratio of 2: 1.

(Synthetic example Core shell polymer (D-1) to (D-6))
1-1. Formation of core layer Synthesis example 1-1-1; Preparation of polybutadiene rubber latex (R-1) In a pressure resistant polymerizer, 200 parts of deionized water, 0.03 part of tripotassium phosphate, potassium dihydrogen phosphate 0. Add 25 parts, 0.002 part of ethylenediamine tetraacetate disodium (EDTA), 0.001 part of ferrous sulfate heptahydrate (Fe) and 0.2 part of sodium dodecylbenzenesulfonate (SDS), and stir. After sufficiently replacing the nitrogen with nitrogen to remove oxygen, 100 parts of butadiene (BD) was added into the system and the temperature was raised to 45 ° C. 0.015 parts of paramentan hydroperoxide (PHP) and then 0.04 part of sodium formaldehyde sulfoxylate (SFS) were added to initiate polymerization. At 4 hours from the start of polymerization, 0.3 part of SDS, 0.01 part of PHP, 0.0015 part of EDTA and 0.001 part of Fe were added. Further, 0.4 part of SDS was added 7 hours after the polymerization. At 10 hours after the polymerization, the residual monomer was volatilized and removed under reduced pressure to complete the polymerization, and a latex (R-1) containing polybutadiene rubber particles was obtained. The polymerization reaction rate was 99% or more. The number average particle size of the polybutadiene rubber particles contained in the obtained latex was 0.14 μm.

1-2. Preparation of core-shell polymer (formation of shell layer)
Synthesis Example 1-2-1; Preparation of latex (D-1LX) containing core-shell polymer (D-1) A 5-port glass container equipped with a reflux condenser, a nitrogen inlet, an additional port for monomers and emulsifiers, and a thermometer. 1575 parts of latex (R-1) (corresponding to 518 parts of polybutadiene rubber particles) and 315 parts of deionized water obtained in Synthesis Example 1-1 were charged into the mixture, and the mixture was stirred at 60 ° C. while performing nitrogen substitution. After adding 0.024 part of EDTA, 0.006 part of Fe and 1.2 part of SFS, graft monomer (42 parts of butyl acrylate (BA), 42 parts of methyl methacrylate (MMA), 6 parts of 4-hydroxybutyl acrylate (4-HBA)). ) And a mixture of 0.4 parts of CHP were continuously added over 2 hours for graft polymerization. After the addition was completed, the reaction was terminated with further stirring for 2 hours to obtain a latex (D-1LX) of the core-shell polymer (D-1). The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-1) was 85% based on the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-1) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be 1 ° C. from the composition ratio.

Synthesis Example 1-2-2; Preparation of Latex (D-2LX) Containing Core-Shell Polymer (D-2) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers The latex (D-2) of the core-shell polymer (D-2) was the same as in Synthesis Example 1-2-1 except that <BA41.4 part, MMA41.4 part, 4-HBA7.2 part> was used instead of. -2LX) was obtained. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-2) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-2) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be 0 ° C. from the composition ratio.

Synthesis Example 1-2-3; Preparation of Latex (D-3LX) Containing Core-Shell Polymer (D-3) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers The latex (D) of the core-shell polymer (D-3) was the same as in Synthesis Example 1-2-1 except that <BA39.6 part, MMA39.6 part, 4-HBA10.8 part> was used instead of. -3LX) was obtained. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-3) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-3) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be -2 ° C. from the composition ratio.

Synthesis Example 1-2-4; Preparation of Latex (D-4LX) Containing Core-Shell Polymer (D-4) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers A latex (D-4LX) of the core-shell polymer (D-4) was obtained in the same manner as in Synthesis Example 1-2-1 except that <BA39 part, MMA39 part, 4-HBA12 part> was used instead of. .. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-4) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-4) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be -3 ° C from the composition ratio.

Synthesis Example 1-2-5; Preparation of Latex (D-5LX) Containing Core-Shell Polymer (D-5) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers In the same manner as in Synthesis Example 1-2-1 except that <BA38.1 part, MMA38.1 part, 4-HBA13.8 part> was used instead of -5LX) was obtained. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-5) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-5) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be -4 ° C. from the composition ratio.

Synthesis Example 1-2-6; Preparation of Latex (D-6LX) Containing Core-Shell Polymer (D-6) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers The latex (D-6LX) of the core-shell polymer (D-6) was the same as in Synthesis Example 1-2-1 except that <BA26.8 part, MMA56 part, 4-HBA7.2 part> was used instead of. ) Was obtained. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-6) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-6) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be 26 ° C. from the composition ratio.

Synthesis Example 1-2-7; Preparation of Latex (D-7LX) Containing Core-Shell Polymer (D-7) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers A latex (D-7LX) of the core-shell polymer (D-7) was obtained in the same manner as in Synthesis Example 1-2-1 except that <BA45 part, MMA45 part> was used instead of. The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-7) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-7) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be 4 ° C. from the composition ratio.

Synthesis Example 1-2-8; Preparation of Latex (D-8LX) Containing Core-Shell Polymer (D-8) In Synthesis Example 1-2-1, <BA42 parts, MMA42 parts, 4-HBA6 parts> as graft monomers Latex (D-8LX) of the core-shell polymer (D-8) was used in the same manner as in Synthesis Example 1-2-1 except that <BA42 part, MMA42 part, and glycidylmethacrylate (GMA) 6 part> were used instead of. Got The polymerization reaction rate was 99% or more. The amount of the rubber component of the core-shell polymer (D-8) was 85% from the charged amount and the reaction rate. The number average particle size of the core-shell polymer (D-8) contained in the obtained latex was 0.15 μm, and the MEK insoluble content was 98%. The Tg of the shell polymer was calculated to be 7 ° C. from the composition ratio.
The core-shell polymers of the above synthetic examples are summarized in Table 1.

1-3. (Preparation of dispersion (F-1 to F-14) in which core-shell polymers (D-1 to D-8) are dispersed in polyether polyols (A-1 to A-7) or epoxy resin (B-1))
100 parts of MEK was introduced into a 1 L mixing tank at 25 ° C., and 30 parts of the core-shell polymer (D) latex obtained in the above synthesis example was charged while stirring. After mixing uniformly, 150 parts of water was added at a supply rate of 60 parts / minute. When the stirring was immediately stopped after the end of the supply, a slurry liquid consisting of a floating aggregate and an aqueous phase partially containing an organic solvent was obtained. Next, the aqueous phase was discharged from the discharge port at the bottom of the tank. 70 parts of MEK was added to the obtained aggregate and mixed uniformly to obtain a dispersion in which the core-shell polymer was uniformly dispersed. The dispersion was placed in a 500 ml glass container and mixed with 45 parts of the polyether polyol (A). However, the dispersion (F-8) was mixed with the epoxy resin (B) instead of the polyether polyol (A). MEK was removed from this mixture with a rotary evaporator. In this way, a dispersion (F) in which the core-shell polymer (D) was dispersed in 40% by weight in the polyether polyol (A) or the epoxy resin (B) was obtained. Table 2 summarizes the blending amounts.

(Examples 1 to 11, Comparative Examples 1 to 7)
According to the formulations shown in Tables 3 to 4, first, the components (A), (B), (E), (F), (G) and (H) are weighed, and the stirrer (rotational revolution mixer, bubble squirrel). It was mixed uniformly using Neritaro (manufactured by Shinky Co., Ltd.). Ingredients (C) and (I) were weighed and added to the obtained mixture, respectively, and uniformly mixed using a stirrer to obtain an epoxy resin composition. The obtained epoxy resin composition was applied to a cold-rolled steel sheet (thickness 0.8 mm) using an applicator, left at room temperature for 3 days or more to cure, and then left at 60 ° C. for 3 hours to sufficiently cure. The test plate was allowed to stand at 23 ° C. for one day, and then the thickness of the coating film was measured to evaluate the pencil hardness, impact resistance and heat impact resistance.
The results are shown in Tables 3 and 4.

From Tables 3 to 4, it can be seen that the cured product obtained from the epoxy resin composition for paint of the present invention is excellent in hardness, impact resistance and heat resistance.

Claims (10)

A polyether polyol (A) having a hydroxyl equivalent of 350 to 900 g / Eq, an epoxy resin (B), a phenalkamine curing agent (C), a core-shell polymer (D) containing 0.055 to 0.140 mmol / g of a hydroxyl group, and a core-shell polymer (D). An epoxy resin composition for paints containing one or more inorganic fillers (E) selected from the group consisting of barium sulfate, mica, talc, iron oxide, zinc phosphate, and titanium oxide.
When the total amount of (A), (B), (C), (D), and (E) is 100% by weight,
The content of (A) is 0.5 to 5.0% by weight,
The content of (D) is 1.5 to 5.0% by weight,
The content of (E) is 30 to 75% by weight,
Epoxy resin composition for paints. The epoxy resin composition for paint according to claim 1, wherein the polyether polyol (A) is at least one selected from the group consisting of polyoxypropylene diol, polyoxypropylene triol, polyoxybutylene diol and polyoxybutylene triol. The epoxy resin composition for paint according to claim 1 or 2 , wherein the hydroxyl group equivalent of the polyether polyol (A) is 450 to 900 g / Eq. The epoxy resin composition for paint according to any one of claims 1 to 3, wherein the core-shell polymer (D) is a core-shell polymer having a number average particle diameter of 0.01 to 0.6 μm . The core layer of the core-shell polymer (D) contains one or more substances selected from the group consisting of a diene rubber, a (meth) acrylate rubber, an organosiloxane rubber, a styrene polymer and a (meth) acrylate polymer. The epoxy resin composition for a paint according to any one of claims 1 to 4. The epoxy resin composition for paint according to any one of claims 1 to 5, wherein the glass transition temperature of the polymer constituting the shell layer of the core-shell polymer (D) is −40 to 20 ° C. The epoxy resin composition for paint according to any one of claims 1 to 6, wherein the core-shell polymer (D) has a hydroxyl group content of 0.080 to 0.140 mmol / g. The cured product of the epoxy resin composition for paint according to any one of claims 1 to 7. The cured product of the epoxy resin composition for paint according to claim 8, wherein the pencil hardness is 3H or more. The cured product of the epoxy resin composition for paint according to claim 8 or 9 , wherein the coating film thickness is 100 to 500 μm.