JPH11263936A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating composition highly balanced in qualities such as weatherability, water resistance, storage stability, adhesiveness to the base, glass, pigment dispersibility, etc., and presenting films excellent in stain resistance. SOLUTION: This coating composition is constituted of (B) a copolymer comprising an alkoxysilyl group-containing radically polymerizable monomer, a carboxyl group-containing radically polymerizable monomer, a polyalkylene glycol mono(meth)acrylate and, if needed, a radically polymerizable monomer copolymerizable with said monomers dispersed or dissolved in (A) a water-based polymer dispersion, and a part or the whole of the carboxyl groups of the acrylic copolymer are neutralized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition comprising a water-based acrylic resin dispersion as a main component and having excellent stain resistance. In particular, a coating formed from the composition is a hydrophilic coating. Because it has a surface, it has excellent stain resistance, and because it has excellent adhesion to the base material, water resistance, durability, etc., it can be used for a wide range of applications such as paints, coating agents, binders for fibers and nonwoven fabrics, rust inhibitors, It can be awarded in these technical fields.

[0002]

2. Description of the Related Art Conventionally, curable copolymers having a hydrolyzable silyl group represented by an alkoxysilyl group have been widely used for applications such as adhesives, sealing materials, paints and coating agents. However, in these application fields, in order to avoid harm to the human body and environmental pollution due to volatilization of the organic solvent, an aqueous material that does not use an organic solvent is required, and the curable copolymer having the alkoxysilyl group is required. The need for aqueous emulsification has also increased.

[0003] A curable copolymer having an alkoxysilyl group is originally not easily obtained in the form of a stable aqueous emulsion because it has a property of crosslinking while hydrolyzing. For this reason, various attempts have been made to obtain an aqueous emulsion having excellent storage stability.
For example, Japanese Unexamined Patent Publication (Kokai) No. 3-227212 discloses that the above-mentioned monomer is used for the purpose of stabilizing the obtained curable copolymer when an aqueous emulsion polymerization of a monomer having an alkyl (meth) acrylate and an alkoxysilyl group is carried out. A method has been proposed in which a specific water-soluble monomer such as acrylamide, acrylic acid or styrene sulfonic acid is used in an amount of about 0.1 to 5% by weight in addition to the monomer to carry out copolymerization.

In Japanese Patent Application Laid-Open No. 7-149840, we disclosed a method of supplying an aqueous dispersion of a monomer in which an oil-soluble initiator was dissolved into heated and stirred water, that is, by using a so-called microsuspension polymerization method. Thus, an aqueous curable composition having good crosslinking properties was obtained. However, the coating film formed from this composition is excellent in weather resistance and water resistance due to the action of an alkoxysilyl group having room temperature crosslinkability, but is resistant to contamination such as rain streaking which has recently become a problem in outdoor applications. Sex was unsatisfactory.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has excellent stain resistance and weather resistance of a coating film.
It is an object of the present invention to obtain a coating composition in which qualities such as water resistance, storage stability, adhesion to a substrate, gloss, and pigment dispersibility are highly balanced.

[0006]

Under these circumstances, the present inventors have conducted intensive studies and as a result, have found that a water-soluble or water-dispersible acrylic copolymer of a specific composition is added to an aqueous dispersion of a polymer in a specific amount. It has been found that the above-mentioned problems can be solved by blending, and the present invention has been completed.

That is, the present invention provides (A) an aqueous dispersion of a polymer, (B) an alkoxysilyl group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and a polyalkylene glycol mono ( A copolymer comprising meth) acrylate and a radical polymerizable monomer copolymerizable with these monomers as necessary, wherein a part or all of the carboxyl groups are neutralized. The present invention provides a coating composition obtained by dissolving or dispersing an acrylic copolymer.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The aqueous dispersion of the polymer as the component (A) of the present invention is not particularly limited. Examples of the polymer include an acrylic polymer, a fluoropolymer, and a vinyl acetate polymer. And an epoxy polymer. An acrylic polymer which is a polymer of a (meth) acrylic acid ester is preferable. Examples of the (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and (meth) acrylate. ) Lauryl acrylate, alkyl (meth) acrylates such as stearyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, perfluoroalkyl (meth) acrylate, glycidyl (Meth) acrylate,
Polyalkylene glycol mono (meth) acrylate,
Polycaprolactone mono (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate and the like can be mentioned. Among these, an alkyl (meth) acrylate having an alkyl group having 1 to 8 carbon atoms and a (meth) acrylic acid having an alkylene group having 2 to 3 carbon atoms because the obtained polymer has excellent coating film properties. Hydroxyalkyl is preferred.

More preferred aqueous dispersions of acrylic polymers include (meth) acrylates, alkoxysilyl group-containing radical polymerizable monomers and radical polymerizable monomers copolymerizable with the monomers. In an aqueous medium, a resin dispersion having a particle size of 0.02 to 1.0 μm obtained by radical polymerization such as emulsion polymerization, dispersion polymerization, or suspension polymerization is preferable, and particularly, a resin dispersion obtained by microsuspension polymerization is preferable. The body is preferred. The alkoxysilyl group-containing radical polymerizable monomer used as the polymerization raw material is a compound having a group represented by the following general formula (1).

[0010]

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(Wherein, R ¹ represents a monovalent hydrocarbon group selected from an alkyl group, an aryl group and an aralkyl group having 1 to 10 carbon atoms, R ² represents a radical polymerizable group, and X represents an alkoxy group. Or a halogen atom, and a is an integer from 0 to 2. When each of X and R ¹ bonded to Si is two or more, they may be the same or different groups. )

In the general formula (1), in X, the alkoxy group includes a methoxy group, an ethoxy group, a propoxy group,
A butoxy group, a pentanoxy group, a hexanoxy group and the like can be mentioned, and as the halogen atom, F, Cl, Br and I can be mentioned. 4 or less alkoxy groups. As the radical polymerizable group for R ² , an ethylenically unsaturated group is preferable, and a functional group having high radical polymerizability such as a (meth) acryloyl group, a styryl group, a vinyl ester group, and a vinyl ether group is more preferable.

Specific examples of the alkoxysilyl group-containing radical polymerizable monomer include vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane. Silane,
Vinylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, vinyltripropoxysilane, vinylmethyldipropoxysilane, γ-methacryloxypropyltripropoxysilane and γ-methacryloxypropyl Methyl dipropoxysilane and the like can be mentioned. Among these, one kind or two or more kinds may be used in combination.

Radical polymerizable monomers copolymerizable with the above-mentioned monomers as other polymerization raw materials include (meth) acrylic acid, itaconic acid, maleic acid, vinyl acetate, vinyl propionate, styrene, α -Methylstyrene and the like. These monomers can be used alone, but generally, a plurality of components are selected so as to balance the properties of the coating film. Preferable examples of these monomers include styrene and (meth) acrylic acid because they are excellent in copolymerizability and the properties of the resulting copolymer in coating film are excellent.

The amount of (meth) acrylate used is
Based on the total amount of the monomers, the amount is preferably 50 to 95% by weight, and the amount of the alkoxysilyl group-containing radical polymerizable monomer used is preferably 0.1 to 30% by weight. The amount used is preferably from 0 to 30% by weight. (Meta)
If the amount of the acrylate is out of the range of 50 to 95% by weight, the weather resistance, strength and heat resistance of the coating film may be reduced. If the amount of the alkoxysilyl group-containing radically polymerizable monomer is less than 0.1% by weight, the composition may have low crosslinkability, and if it exceeds 30% by weight, the coating may become brittle and the adhesion may be reduced. is there.

The aqueous dispersion of the acrylic polymer (A) of the present invention is obtained by radical polymerization of the above monomers in an aqueous medium. As the radical initiator, a peroxide or azo initiator used in ordinary radical polymerization may be used. For example, when microsuspension polymerization, which is a preferred polymerization method, is used, an oil-soluble radical initiator having a solubility in water at 20 ° C. of 10% by weight or less and dissolving in the monomer mixture at the reaction temperature is used. Specifically, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1-azobis-1-cyclohexanecarbonitrile and dimethyl-2,2'-azo Azo initiators such as bisisobutyrate, organic peroxides such as lyloyl peroxide, benzoyl peroxide, dicumyl peroxide, cyclohexanone peroxide di-n-propylperoxydicarbonate and t-butylperoxypivalate Is preferably used. The preferred use amount of the radical initiator is 0.05 to 5% by weight, and more preferably 0.1 to 3% by weight. If the amount is less than 0.05% by weight, the odor becomes a problem because the monomer remains, and if it exceeds 5% by weight, the polymerization rate is too high and it is difficult to control heat generation.

In producing the aqueous dispersion of the acrylic polymer (A), various surfactants such as anionic, nonionic and cationic surfactants commonly used in ordinary emulsion polymerization can be used. It is preferable to use a surfactant having a radical polymerizable group in order to impart a high degree of water resistance and weather resistance to a coating obtained by forming a polymer emulsion. A typical example of the radically polymerizable surfactant is a compound having a radically polymerizable unsaturated double bond and a hydrophilic portion in a molecule, and a polyoxyalkylene group represented by the following general formula (2) and an ion. It is a radically polymerizable surfactant containing a dissociable group.

Z- (AO) _n -Y (2) (wherein, Z represents a structural unit having a radical polymerizable double bond, AO represents an oxyalkylene group, and Y represents an ion-dissociable group. , N is an integer of 2 or more.) In the general formula (2), preferred Z is a hydrophobic group such as an aromatic hydrocarbon group, an alkyl-substituted aromatic hydrocarbon group, a higher alkyl group or an alicyclic hydrocarbon group. It is a structural unit in which a functional group and a radical polymerizable double bond are combined. As the radical polymerizable double bond, a (meth) allyl group, a propenyl group, a butenyl group, or the like is preferable.

The preferred ionicity of the surfactant of the formula (2) is an anion. As Y, a salt in which a cation is ionically bonded to an anion covalently bonded to an oxyalkylene group is preferable. Preferred examples of Y, -SO ₃ N
_{a, -SO 3 NH 4, -COONa} , -COONH 4,
-PO ₃ Na _2, and -PO ₃ (NH _{4) 2} and the like, -SO ₃ Na or -SO ₃ NH ₄ is more preferred.
_N in the group (AO) _n is an integer of 2 or more;
0 is preferred. If n is less than 5 or more than 50, the stability of the emulsion tends to decrease, and the physical properties of the coating film tend to decrease. The unit A in the group (AO) _n , that is, the alkylene group, is preferably an ethylene group or a propylene group.
The preferred use amount of the surfactant is 0.2 to 20% by weight, and more preferably 0.2 to 10% by weight. 0.
If it is less than 2% by weight, the dispersion stability at the time of polymerization decreases, and if it exceeds 20% by weight, the water resistance of the cured coating film decreases.

Specific examples of the surfactant include, for example, compounds represented by the following formulas (3) to (5). In the formulas (3) and (4), R ³ is preferably a linear or branched alkyl group having 6 to 18 carbon atoms.
In the formula (5), R ⁵ is preferably an alkyl group having 8 to 24 carbon atoms, and R ⁴ is a hydrogen atom or a methyl group. Further, specific examples of Y in formulas (3) to (5) are as described above.

[0021]

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[0022]

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[0023]

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Preferred examples of these surfactants are commercially available. For example, Aqualon (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) represented by the following formula (6) and Adecali Ripe (Asahi Denka Kabushiki Kaisha) represented by the following formula (7) Industrial company). Aqualon HS
05, HS10 and HS20 are each represented by the formula (6)
Wherein n, which is the degree of condensation of polyoxyethylene groups, is 5, 10 or 20, and
-10N is a compound of the formula (7) wherein n is 10.

[0025]

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The compound of the formula (6) is represented by the formula (3)
R ³ is an example of a nonyl group, A is an ethylene group, and Y is an example of SO ₃ NH ₄ .

[0027]

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The compound of the formula (7) is represented by the formula (4)
R ³ is an example of a nonyl group, A is an ethylene group, and Y is an example of SO ₃ NH ₄ .

Microsuspension polymerization, which is a preferred polymerization method, comprises:
After dissolving the oil-soluble radical polymerization initiator in the monomer mixture, it is dispersed in an aqueous medium with a dispersing device having high shear energy (hereinafter, this monomer dispersion is referred to as a pre-emulsion), and the pre-emulsion is heated. In this method, the polymerization is completed by adding the mixture to an aqueous medium. This method has the same particle size as ordinary emulsion polymerization products regardless of suspension polymerization.
It is characterized in that a dispersion of (submicron level) is obtained, and is called microsuspension polymerization or microsuspension polymerization in the sense of micron-sized suspension polymerization.

In the microsuspension polymerization, polymerization proceeds by the same mechanism as in the suspension polymerization method except that the particle size is small because the particles are polymerized as they are. Unlike a general emulsion polymerization in which a resin particle grows from an emulsifier micelle using a water-soluble initiator, the composition does not become uneven due to a difference in solubility of each monomer in an aqueous phase. Accordingly, the monomer composition and the reactive group density of each particle become the same, and a curable resin dispersion having excellent performance can be obtained.

In order to produce the resin dispersion of the component (A) by microsuspension polymerization, first, a radical polymerizable composition is emulsified and dispersed in an aqueous medium to prepare a pre-emulsion. Usually, a monomer component in water in which a surfactant is dissolved in advance,
The mixture of the oil-soluble initiator is emulsified and dispersed. The method of emulsification and dispersion is not particularly limited. However, when a normal rotary homomixer is used, it is desirable to increase the output and apply high shear. If a fine emulsion cannot be obtained with a rotary homomixer alone, the mixture is treated with a rotary homomixer, and then granulated using a high-pressure emulsifier / disperser (homogenizer) or a disperser having a high shear energy such as a turbine mixer. A method of reducing the diameter is recommended.

The average particle size of the pre-emulsion is from 0.02 to
It is necessary to be in the range of 10 μm, and 0.05 to 5.0.
μm is preferred. By using a pre-emulsion having such a particle size, the particle size of the emulsified dispersion obtained after the polymerization can be reduced, and the uniformity of the composition is improved. The properties such as water resistance and water resistance are excellent. The polymerization operation of the pre-emulsion obtained by the above operation is carried out by a method of continuously or intermittently supplying the pre-emulsion into an aqueous medium heated under stirring. At this time, the preferable amount of the aqueous medium charged into the polymerization reactor is in the range of 10 to 100 parts by weight per 100 parts by weight of the pre-emulsion. The aqueous medium contains at least 80% water, and may contain water-compatible solvents and additives such as alcohols, if necessary.

For the purpose of improving the emulsion stability during polymerization, the surfactant used for preparing the pre-emulsion may be charged in an aqueous medium. For the purpose of preventing the hydrolysis of the alkoxysilyl group during the polymerization, a known pH buffer may be added. If the pH during polymerization is kept at 7 to 10 using a pH buffer such as sodium bicarbonate, decomposition of the alkoxysilyl group is prevented, and an alkoxysilyl group-containing resin dispersion is obtained. On the other hand, when polymerizing without using a pH buffer,
The alkoxysilyl group is hydrolyzed and converted into a silanol group to form a silanol group-containing resin dispersion.

The water-soluble or water-dispersible acrylic copolymer which is the component (B) of the present invention comprises an alkoxysilyl group-containing radical polymerizable monomer, a carboxyl group-containing radical polymerizable monomer, and a polyalkylene glycol. A copolymer comprising a mono (meth) acrylate and a radically polymerizable monomer copolymerizable with these monomers as necessary, wherein a part or all of the carboxyl group is a medium. It is something that is summed up.

Examples of the alkoxysilyl group-containing radical polymerizable monomer include the same ones as those used in the acrylic water-based resin as the component (A).

Examples of the carboxyl group-containing radical polymerizable monomer include compounds having both a carboxyl group and a vinyl group in the molecule, such as (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, and fumaric acid. Can be Among them, acrylic acid and methacrylic acid are preferably used.

The polyalkylene glycol mono (meth) acrylate is a compound in which a (meth) acryloyl group is bonded to one end of the polyalkylene glycol, and its preferred number average molecular weight is 160 to 5,000. Polyethylene glycol is particularly preferred as the polyalkylene glycol. The terminal group opposite to the (meth) acryloyl group is preferably a hydroxyl group or an alkoxy group, particularly preferably an alkoxy group.

In the acrylic copolymer of the present invention, a radical polymerizable monomer (hereinafter, referred to as “other monomer”) copolymerizable with the above monomer can be used as needed. And other monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate,
Alkyl (meth) acrylates such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, 2- (meth) acrylate
Hydroxyethyl, 2-hydroxypropyl (meth) acrylate, perfluoroalkyl (meth) acrylate,
Glycidyl (meth) acrylate, polyalkylene glycol mono (meth) acrylate, polycaprolactone mono (meth) acrylate, (meth) acrylic acid N, N
-(Meth) acrylates such as diethylaminoethyl, vinyl acetate, vinyl propionate, styrene, α
-Methylstyrene and the like. These monomers can be used alone, but generally, a plurality of components are selected so as to balance the properties of the coating film. The copolymerization ratio of these other monomers is preferably from 0 to 60% by weight.

Among these other monomers, those having 1 to 1 carbon atoms
An alkyl (meth) acrylate having an alkyl group of 8;
Styrene, hydroxyalkyl (meth) acrylate and perfluoroalkyl (meth) acrylate having an alkylene group having 2 to 3 carbon atoms are preferable from the viewpoint of copolymerizability, coating film properties and the like. Further, at least 50 parts of (meth) acrylic acid ester is used with respect to 100 parts of the total weight of the monomer components, so that the coating film properties such as weather resistance, strength and heat resistance of the coating film are maintained at a high level. In this respect, it is preferable. Further, it is preferable that 0.2 to 30% by weight of perfluoroalkyl (meth) acrylate is copolymerized. Thus, when a heat treatment is performed for the purpose of accelerating the crosslinking reaction of the coating film, the hydrophilic portion of the coating film surface may sink into the interior due to heat and lose the stain resistance function. Energy can be reduced. The perfluoroalkyl (meth) acrylate includes 3 to 15 carbon atoms.
Those having a perfluoroalkyl group are preferred.

In the acrylic copolymer (B), the content of the alkoxysilyl group-containing radically polymerizable monomer unit is preferably from 2 to 40% by weight. If the copolymerization ratio is less than 2% by weight, the crosslinkability of the composition may decrease, and if it exceeds 40% by weight, the coating may become brittle and the adhesion may decrease. Further, the content ratio of the carboxyl group-containing radical polymerizable monomer unit is preferably from 2 to 30% by weight. If the copolymerization ratio is less than 2% by weight, the solubility in water may be insufficient and a uniform dispersion may not be obtained. If the copolymerization ratio exceeds 30% by weight, the water resistance of the coating film may decrease. The content ratio of the polyalkylene glycol mono (meth) acrylate unit is preferably from 20 to 80% by weight. If the copolymerization ratio is less than 20% by weight, stain resistance may not be imparted to the coating film, and if it exceeds 80% by weight, the water resistance of the coating film may be reduced.

As a method for producing the acrylic copolymer (B) of the present invention, a method in which the above-mentioned monomer is solution-polymerized using an organic solvent and neutralized is preferred. Examples of the organic solvent include alcohol solvents such as methanol, ethanol, isopropanol and butanol; ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone; acetate solvents such as ethyl acetate, propyl acetate and butyl acetate; toluene, xylene and the like. And hydrocarbon compounds such as hexane and cyclohexane. In this, the boiling point is 100 ° C
The following alcohol-based, ketone-based, and acetate-based solvents are preferably used, and specifically, ethanol, isopropanol, acetone, methyl ethyl ketone, and ethyl acetate are preferred.

The solution polymerization may be performed according to a known method, for example, a method of reacting at a temperature of 40 to 150 ° C. in the presence of a radical initiator such as an azo compound or an organic peroxide. If necessary, an appropriate amount of a chain transfer agent such as n-dodecyl mercaptan, mercaptoacetic acid, mercaptoethanol, thiomalic acid, mercaptopropionic acid may be used.

The number average molecular weight of the copolymer before neutralization is 1,000
-30,000 is preferred, and 2,000-20,000 is more preferred.
If the number average molecular weight of the copolymer before neutralization is less than 1,000, the durability of the coating film is poor, while if it exceeds 30,000, the solution viscosity tends to be excessively high. Incidentally, the number average molecular weight in the present invention,
It is the molecular weight in terms of polystyrene determined by gel permeation chromatography.

As the basic substance used for neutralization, ammonia, monomethanolamine, dimethylamine, diethylamine, triethylamine, triethanolamine,
Examples thereof include organic amine compounds such as diethylethanolamine and dimethylethanolamine, and alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide. The amount of the basic substance used is preferably 20 to 100 mol%, more preferably 40 to 80 mol%, based on the amount of carboxyl groups in the copolymer before neutralization. If it is less than 20 mol%, the solubility in water is insufficient, and it tends to aggregate during neutralization. In order to enhance the storage stability of the copolymer, the pH after neutralization is preferably set to 6 to 8.

As a specific neutralization operation, a method in which an aqueous solution of a basic substance is added to an organic solvent solution of the copolymer obtained by the above-mentioned polymerization to neutralize it is simple. The aqueous solution or aqueous dispersion of the carboxylate-containing copolymer thus obtained can be removed by removing the organic solvent under reduced pressure or adding water, if necessary, to obtain a suitable solid concentration of 10 to 40% by weight. Acrylic copolymer aqueous solution or aqueous dispersion is obtained. When a water-soluble organic solvent such as alcohol is used as the organic solvent, it is not always necessary to remove the organic solvent. As the acrylic copolymer as the component (B), a water-soluble copolymer is preferable.

The coating composition of the present invention contains the polymer of the component (A) and the water-soluble or water-dispersible acrylic copolymer of the component (B), and the components (A) and (B) The ratio of the polymer (A) is 70 based on the total amount.
To 99 parts by weight, more preferably 8 to 99 parts by weight.
0 to 98 parts by weight. Acrylic water based resin ratio of 7
If the amount is less than 0% by weight, the weather resistance and water resistance of the coating film may decrease, and if it exceeds 99% by weight, the stain resistance may decrease.

The method for producing the composition of the present invention includes:
The polymer of the component (A) and the acrylic copolymer of the component (B) may be mixed in the presence of an aqueous medium. The method of mixing the two components is not particularly limited, and may be mixed by a usual method such as stirring or shaking. At the mixing time, an aqueous solution or aqueous dispersion of an acrylic copolymer may be added at the time of producing a polymer dispersion (such as at the time of preparing a pre-emulsion), or a polymer dispersion and an acrylic copolymer may be added. May be mixed. Further, for the purpose of enhancing the storage stability after mixing, the pH can be adjusted by adding a buffer.

A film can be obtained by applying the composition of the present invention to a base material and volatilizing water at room temperature or under heating. If the polymer has an alkoxysilyl group or a silanol group together with the fusion and continuation of the polymer (A) as the main component, the polymer is further crosslinked and cured by a self-condensation reaction of these functional groups. At this time, the water-soluble or water-dispersible acrylic copolymer (B) improves the uniformity of the coating film by filling gaps where fusion is incomplete, and further develops a stain-resistant function by covering the coating surface. Let it. When the acrylic copolymer itself has a silanol group, the self-crosslinking and the crosslinking reaction with the acrylic copolymer (B) proceed, and the interfacial adhesion and durability are imparted.

When the polymer has an alkoxysilyl group or a silanol group, the crosslinking reaction proceeds rapidly even at room temperature. However, when it is desired to further promote crosslinking, as a curing catalyst, for example, isopropyl triisostearoyl titanate, isopropyl tri (dioctyl pyrol) Organic titanate compounds such as (phosphate) titanate, or organic tin compounds such as tin dioctylate, dibutyltin dilaurate, and dibutyltin malate, or organic acid catalysts such as paratoluenesulfonic acid may be used.

The coating composition of the present invention includes various additives commonly used in coatings, coating agents, binders for fibers and non-woven fabrics, such as clay, talc, calcium carbonate, titanium white, colloidal silica, etc. Fillers, pigments, dyes, film-forming aids, plasticizers, various surfactants used for wetting, dispersion, defoaming, etc., antistatic agents, thickeners,
Thixotropic agents, antifreezing agents, various cross-linking agents, antifogging agents, lubricants, metal powders, antioxidants, UV inhibitors, antibacterial agents, antifungal agents, tackifiers, rust inhibitors, etc. as required An appropriate amount can be added.

The coating composition of the present invention is suitable as a coating agent or a binder, and the substrate to be applied includes, for example, glass, slate, metal, wood or plastic. The intended use is as follows: paints for building materials that are hardly stained with rain streaks, paints for acid rain resistance, antifouling paints, water repellents for inorganic building materials, moisture-proof coatings for electric and electronic components,
Back coat agent for magnetic tape, sealing agent, fiber treatment agent, binder for fiber / non-woven fabric, binder for ink,
An adhesive and the like can be mentioned.

[0052]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but this is merely an example and does not limit the present invention. In each of the examples, the “blending part” or “part” in the component blending is all parts by weight, and “%” is% by weight.

Reference Example 1 Production of Aqueous Dispersion of Acrylic Polymer (Component (A)) A monomer, an emulsifier, an initiator, a pH buffer and water shown in Table 1 were mixed in the amounts shown in Table 1. Pre-emulsion (monomer emulsion)
Was prepared. The particle size of the monomer mixture was about 0.2 μm.

Next, 70 parts of deionized water was charged as an aqueous medium into a flask equipped with a stirrer, a thermometer, and a cooler.
After raising the liquid temperature to 85 ° C., the above pre-emulsion was added dropwise over 3 hours with stirring. After completion of the dropwise addition, the temperature of the internal solution was raised to 90 ° C., and the temperature was further maintained for 1 hour to complete polymerization.
No liquid separation and blocking occurred during the polymerization, and the polymerization was carried out stably. The average particle size of the obtained resin dispersion is 0.1
At 6 μm, the pH was 8.5 and the solids content was 44%. The ethanol content in the emulsion was 0.03%, and the hydrolysis rate was 2% or less.

[0055]

[Table 1]

In Table 1, "AQUALON HS10" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is a compound of the formula (6) wherein n = 10.

Reference Example 2 Production of Water-Soluble Acrylic Copolymer (Component (B)) 12 parts of γ-methacryloxypropyltriethoxysilane was placed in a glass flask having a stirrer, a reflux condenser, a temperature system and a nitrogen blowing tube. , 38 parts of cyclohexyl methacrylate, polyethylene glycol monomethacrylate (NK ester M-90G; manufactured by Shin-Nakamura Chemical Co., Ltd.) 40
Parts, acrylic acid 10 parts, mercaptopropionic acid 1.0
And 130 parts of isopropanol were charged, and the temperature was raised to 75 ° C. In the flask, 2,2'-azobis- (2-
A solution in which 1.5 parts of methylbutyronitrile) (ABN-E; manufactured by Nippon Hydrajin Kogyo Co., Ltd.) was dissolved in 20 parts of isopropanol was supplied over 3 hours.
Held. Thereafter, 0.5 parts of ABN-E was further added to maintain the reaction solution at the reflux temperature, and refluxed for 4 hours to complete the polymerization. The number average molecular weight of the obtained copolymer before neutralization is
6,200 and the weight average molecular weight was 15,000. A mixed solution of 4.82 parts of a 25% aqueous ammonia solution and 355 parts of distilled water was added to 200 parts of the copolymer solution before neutralization and mixed. The pressure in the flask was reduced, and about 280 parts of a mixture of isopanol and water was distilled. This gave a clear aqueous solution of the acrylic copolymer. The non-volatile content of the solution is 27.4%
Was 6.4.

Reference Example 3 Production of Water-Soluble Acrylic Copolymer (Component (B)) Into 200 parts of the copolymer solution before neutralization in Reference Example 2, 2.46 parts of sodium hydroxide (96% purity) was distilled. A mixed solution of 357 parts of water was added and mixed, and the inside of the flask was depressurized to distill off about 310 parts of a mixture of isopropanol and water to obtain a transparent aqueous solution of an acrylic copolymer. The non-volatile content of the solution is 32.4
% And the pH was 6.5.

Reference Example 4 Production of Water-Soluble Acrylic Copolymer (Component (B)) To 200 parts of the copolymer solution before neutralization of Reference Example 2, 1.44 parts of lithium hydroxide (purity: 98%) was distilled. A mixed solution of 358 parts of water was added and mixed, and the inside of the flask was depressurized to distill off about 290 parts of a mixture of isopropanol and water to obtain a transparent aqueous solution of an acrylic copolymer. The non-volatile content of the solution is 28.4%
And the pH was 6.2.

Reference Examples 5 to 10 Production of Water-Soluble Acrylic Copolymer (Component (B)) Polymerization was carried out in the same manner as in Reference Example 2, except that the monomer composition was changed as shown in Table 2, and neutralized. An isopropanol solution of the pre-copolymer was obtained. This copolymer solution was neutralized according to Reference Example 3 to obtain a transparent aqueous solution of a sodium carboxylate type acrylic copolymer.

[0061]

[Table 2] In the table, MTES indicates γ-methacryloxypropyltriethoxysilane, CHMA indicates cyclohexyl methacrylate, FMA indicates perfluorooctylethyl methacrylate, and M-90G indicates polyethylene glycol monomethacrylate (NK ester M-90G; new AA denotes acrylic acid.

Examples 1 to 4 and Comparative Example Aqueous dispersion of acrylic polymer produced in Reference Example 1, aqueous solution of water-soluble acrylic copolymer produced in Reference Examples 2 to 4, and tripropylene glycol-n- Butyl ether (TPNB) was blended at a mixing ratio (in terms of pure content) shown in Table 3 to prepare a composition. Using the obtained composition, a coating film having a film thickness of about 10 μm was formed on a galvanized steel sheet and an allodized aluminum plate using a bar coater. 23 painted boards
℃, 40% RH for 2 weeks (room temperature curing) or 130 ° C for 2 weeks
After holding for 0 minutes (heat curing), the following evaluation was performed on the obtained coating film. Table 3 shows the results. In addition, the number of a composition shows a "part."

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[Table 3] In the table, the evaluation items were evaluated by the following methods. -Pencil hardness: Evaluated according to JIS K 5400 8.4.2. -Water resistance: After immersing the coated plate in water at room temperature for 24 hours, judgment is made based on whitening and gloss of the coating film.は indicates excellent, Δ indicates slightly excellent, and × indicates inferior. -Water resistant contact angle: The contact angle between the cured coating film and water was measured with a goniometer. Stain resistance: Using a commercially available aluminum plate coated with a white paint, the coating agent obtained in each example was applied on the white coated film in the same manner as in Example 1 to form a coated film, Or, it was cured by heating. The coated plate was placed outdoors for three months, and the state of contamination during that period was measured by a color difference meter. Evaluation was made based on the difference (−ΔL) between the initial L value and the L value after outdoor exposure.

Examples 5 to 10 The aqueous dispersion of the acrylic polymer produced in Reference Example 1, the aqueous solution of the water-soluble acrylic copolymer produced in Reference Examples 5 to 10, and TPNB were mixed with each other in an acrylic resin. Polymer 100 parts, water-soluble acrylic copolymer 5 parts, TPN
B 10 parts and 138 parts of water were mixed to prepare a composition. Next, coating films were prepared and evaluated in the same manner as in Examples 1 to 4. Table 4 shows the results.

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[Table 4]

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As is evident from the results of the examples and comparative examples, according to the present invention, stain resistance can be effectively improved without adversely affecting the coating properties such as water resistance. Therefore, it can be applied to a wide range of uses such as paints, coating agents, fibers, binders for nonwoven fabrics, tackifiers / adhesives, and rust inhibitors, and has great industrial value.

Claims (4)

[Claims] 1. An aqueous dispersion of (A) a polymer, wherein (B)
Alkoxysilyl group-containing radical polymerizable monomer, carboxyl group-containing radical polymerizable monomer, polyalkylene glycol mono (meth) acrylate, and, if necessary, a radical polymerizable monomer copolymerizable with these monomers Acrylic copolymer obtained by neutralizing a part or all of the carboxyl group of the constituent monomer,
Is a coating composition in which is dissolved or dispersed. 2. The method according to claim 1, wherein (A) is a (meth) acrylic acid ester, an alkoxysilyl group-containing radical polymerizable monomer, and a radical polymerizable monomer copolymerizable with the monomer.
The coating composition according to claim 1, which is an aqueous dispersion of an acrylic polymer obtained by microsuspension polymerization in an aqueous medium. 3. The coating composition according to claim 1, comprising 70 to 99 parts by weight of the polymer (A) and 30 to 1 part by weight of the acrylic copolymer (B). 4. In the acrylic copolymer (B), the content of the alkoxysilyl group-containing radical polymerizable monomer unit is 2 to 40% by weight, and the content of the carboxyl group-containing radical polymerizable monomer unit is 2 to 40% by weight. The content ratio is 2 to 30% by weight, and the content ratio of the polyalkylene glycol mono (meth) acrylate unit is 20 to 80% by weight.
The coating composition according to any one of claims 1 to 3.