JP2001106978A - Aqueous low-stain coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous low-stain coating composition having excellent compatibility and viscosity stability in compounding an aqueous coating with a stain reducing agent, showing a high gloss value when applied to a gloss paint, capable of greatly improving stain resistance of coating film and prevention of permeation of contaminant, having excellent adhesivity in double coating of coating material. SOLUTION: This aqueous low-stain coating composition comprises (A) an aqueous coating composed of a synthetic resin emulsion as a binder, (B) an amino group-containing silane coupling agent and (C) a modified condensate of an alkoxysilane and is obtained by compounding 100 pts.wt. of solid content of (A) the synthetic resin emulsion with 0.05-3.0 pts.wt. of the component (B) and 1.0-40.0 pts.wt. calculated as SiO2 of the component (C) and adjusting the mixture to pH <=9.0 after the compounding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based low-contamination coating composition, and more particularly to the surface finishing of various materials such as metal, glass, porcelain tile, concrete, siding board, extruded plate, and plastic. The present invention relates to a water-based low-contamination paint composition which can be used and is mainly used for protecting a building such as a building or a civil engineering structure.

[0002]

2. Description of the Related Art In recent years, in the field of paints used for architectural and civil engineering structures, a shift from a solvent-based paint using an organic solvent as a solvent to a water-based paint using water as a solvent is being made. This is to reduce the health hazards for painters and residents,
It is carried out for the purpose of reducing atmospheric environmental pollution, and is becoming more and more aqueous every year.

[0003] Some known water-based paints have the same level of performance as solvent-based paints in terms of weather resistance, water resistance and the like. However, paying particular attention to the stainability, even water-based paints that are said to be low-stainable are far below the level of solvent-based low-stainable paints.

[0004] In general, a coating film made of an aqueous coating material has a lower coating film hardness than a coating film made of a solvent-type coating material, and tends to have higher penetration when contaminants adhere. Therefore, once a contaminant adheres, it is often difficult to remove the stain from the coating film surface.

[0005] As a low-contamination type paint which has solved such a problem, a technique of blending a specific organosilicate and / or a condensate thereof into the paint is disclosed in WO94 / 06870. More specifically, WO94 / 06870
The technology disclosed in US Pat.
Or, by mixing the condensate thereof and performing an acid treatment after the formation of the coating film, the surface of the coating film is made hydrophilic, making it difficult for oily contaminants to adhere, and the attached contaminants are washed away together with water drops such as rainfall. It is characterized by the following.

[0006] However, in the case of WO94 / 06870 in which an organosilicate and / or a condensate thereof is simply added, the hydrolysis / condensation reaction that occurs when the organosilicate and / or a condensate thereof is added to an aqueous paint cannot be controlled. In addition, the viscosity of the coating material sharply increases in a short time, and further, the entire coating material gels, so that even the usual coating operation cannot be performed. Further, even when the coating is performed immediately after mixing to form a coating film, there is a disadvantage that the resistance to the penetration of contaminants is poor.

In addition, there is a problem that the compatibility between the water-based paint and the organosilicate and / or its condensate is poor, and agglomerates are formed after mixing. In particular, a high gloss water-based paint generally called a gloss paint has a disadvantage that the surface gloss is extremely reduced due to the poor compatibility.

[0008] Further, when an aqueous coating material to which an organosilicate and / or a condensate thereof is added is applied and the coating film is dried and cured, when the same coating material or another coating material is applied over the coating film, sufficient adhesion is required. Was not obtained, and the recoating property was poor.

As described above, simply adding an organosilicate and / or a condensate thereof to an aqueous coating composition has a problem that cannot be ignored in practical use, and it is difficult to obtain a coating film having excellent low stainability. there were.

[0010]

Therefore, the problem to be solved by the present invention is that the compatibility and the viscosity stability when the water-based paint and the low-staining agent are mixed are good, and the high gloss aqueous solution is used. When applied to gloss paint, a paint film with a high gloss value can be obtained, the stain resistance of the paint film and the ability to prevent the penetration of contaminants can be dramatically improved. It is an object to provide a water-based low-contamination coating composition that can solve all of these problems.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have combined an aqueous coating composition using a synthetic resin emulsion as a binder, an amino group-containing silane coupling agent, and a modified condensate of alkoxysilane, It has been found that these problems can be solved by setting the pH after the combination to a specific range, and the present invention has been completed.

That is, the present invention relates to the following aqueous coating composition.

1. (A) a water-based paint using a synthetic resin emulsion as a binder, (B) an amino group-containing silane coupling agent, and (C) a modified condensate of an alkoxysilane, wherein the solid content of the synthetic resin emulsion of (A) is 100 (B) is 0.05 to 3.0 parts by weight, and (C) is based on parts by weight.
Is 1.0 to 40.0 parts by weight in terms of SiO ₂ , and the pH after compounding is 9.0 or less. 2. In the synthetic resin emulsion (A), the carboxylic acid-containing monomer is contained in a weight ratio of 5.
It is characterized by containing not more than 0%. 2. The aqueous low-contamination coating composition according to item 1. 3. (C) The modified condensate of alkoxysilane has at least one or more polyoxyalkylene groups. Or 2. 2. The aqueous low-contamination coating composition according to item 1. 4. (C) The modified condensate of an alkoxysilane is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the repeating unit of the polyoxyalkylene group has 1 carbon atom.
1-4, wherein the alkoxyl group has 1-4 carbon atoms. Or 2. 2. The aqueous low-contamination coating composition according to item 1. 5. (C) The modified condensate of an alkoxysilane is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene groups and alkoxyl groups, wherein the repeating unit of the polyoxyalkylene group has 2 carbon atoms.
Wherein the alkoxyl group is an ethoxy group having 2 carbon atoms. Or 2. 2. The aqueous low-contamination coating composition according to item 1.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on its embodiments.

The aqueous low-contamination coating composition of the present invention comprises (A)
Water-based paint using a synthetic resin emulsion as a binder, (B)
An amino group-containing silane coupling agent, and (C) a modified condensate of an alkoxysilane, containing (A), (B),
By adjusting the pH after mixing (C) to 9.0 or less, the compatibility and viscosity stability when mixing the water-based paint and the low-contaminating agent, gloss with gloss paint, and resistance of the formed coating film are improved. Not only is it excellent in stainability and resistance to infiltration of contaminants, but it can also ensure adhesion when a paint is applied over the formed coating film.

The aqueous coating composition (A) in the composition of the present invention comprises:
The synthetic resin emulsion is used as a binder, and contains a film-forming aid, a pigment, an additive, and the like as necessary.

Examples of the synthetic resin emulsion used in the water-based paint (A) of the present invention include an acrylic resin emulsion, an acrylic silicone resin emulsion, a fluororesin emulsion, and a urethane resin emulsion.

[Acrylic resin emulsion]
As the acrylic resin-based emulsion, those obtained by radical copolymerization of an acrylic monomer and another monomer copolymerizable with the acrylic monomer can be used.

The acrylic monomer is not particularly restricted but includes, for example, methyl (meth) acrylate (indicating either methyl acrylate or methyl methacrylate; the same applies hereinafter) and ethyl (meth).
Acrylate, n-butyl (meth) acrylate, i-
Alkyl group-containing (meth) acrylic monomers such as butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and cyclohexyl (meth) acrylate; 2
-Hydroxy group-containing (meth) acrylic monomers such as hydroxyethyl (meth) acrylate; ethylenically unsaturated carboxylic acids such as (meth) acrylic acid; dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate Amino group-containing (meth) acrylic monomers; amide-containing (meth) acrylic monomers such as (meth) acrylamide and ethyl (meth) acrylamide; nitrile group-containing (meth) acrylic monomers such as acrylonitrile An epoxy group-containing (meth) acrylic monomer such as glycidyl (meth) acrylate;

Other monomers copolymerizable with the acrylic monomer include aromatic hydrocarbon vinyl monomers such as styrene, methylstyrene, chlorostyrene and vinyltoluene; maleic acid, itaconic acid, croton Acid, fumaric acid,
Α, β-ethylenically unsaturated carboxylic acids such as citraconic acid; sulfonic acid-containing vinyl monomers such as styrene sulfonic acid and vinyl sulfonic acid; acid anhydrides such as maleic anhydride and itaconic anhydride; vinyl chloride, vinylidene chloride , Chloroprene and other chlorine-containing monomers; hydroxyethyl vinyl ether, hydroxypropyl vinyl ether and other hydroxyl-containing alkyl vinyl ethers; ethylene glycol monoallyl ether, propylene glycol monoallyl ether, diethylene glycol monoallyl ether and other alkylene glycol monoallyl ethers; ethylene and propylene And α-olefins such as isobutylene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate and vinyl pivalate; methyl vinyl ether and ethyl vinyl Ether, butyl vinyl ether, vinyl ether such as cyclohexyl vinyl ether, ethyl allyl ether, an allyl ether such as butyl allyl ether and the like.

When an acrylic resin emulsion is used as the synthetic resin emulsion, durability, cost, etc.
Advantageously, there is a high degree of freedom in resin design and a high gloss in gloss paint.

[Acrylic Silicone Resin Emulsion] The acrylic silicone resin emulsion is obtained by radical copolymerization of a silicon-containing acrylic monomer and another monomer copolymerizable with the silicon-containing acrylic monomer. Can be used.

The silicon-containing acrylic monomer is not particularly limited. For example, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, γ- (meth) acrylic Examples include hydrolyzable silyl group-containing vinyl monomers such as roxypropylmethyldimethoxysilane and γ- (meth) acryloxypropylmethyldiethoxysilane.

As the other monomer copolymerizable with the silicon-containing acrylic monomer, for example, the monomer used in the above-mentioned acrylic resin emulsion can be used without any particular limitation.

When an acrylic silicone resin emulsion is used as the synthetic resin emulsion, weather resistance, yellowing resistance, durability, chemical resistance, stain resistance and the like are advantageous.

[Regarding Fluororesin Emulsion] Fluororesin emulsions include fluorine-containing monomers,
And those obtained by radical copolymerization of a fluorine-containing monomer and another copolymerizable monomer can be used.

Examples of the fluorine-containing monomer include fluoroolefins such as vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, pentafluoroethylene, and hexafluoropropylene; trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) And fluorinated (meth) acrylates such as acrylate and perfluorocyclohexyl (meth) acrylate.

As the other monomer copolymerizable with the fluorine-containing monomer, for example, the monomer used in the above-mentioned acrylic resin emulsion can be used without any particular limitation.

When a fluororesin emulsion is used as the synthetic resin emulsion, weather resistance, yellowing resistance, durability, chemical resistance, stain resistance and the like are advantageous.

[About urethane resin emulsion]
The urethane resin-based emulsion is a generic term for emulsions having urethane bonds in a coating film after the formation of the coating film. That is, it may be one having a urethane bond before the coating film is formed, or one which forms a urethane crosslink by a reaction after the coating film is formed. The form of the emulsion may be a one-part type or a two-part type. As a one-part type, a method of copolymerizing a polymerizable monomer having a urethane bond with another copolymerizable monomer, polymerizing a polymerizable unsaturated monomer in the presence of an aqueous resin having a urethane bond how to,
Examples include a method of mixing an aqueous urethane resin having a reactive group with an emulsion containing a group capable of reacting with the reactive group. Examples of the two-pack type include a combination of a water-dispersible isocyanate and a hydroxyl group-containing emulsion.

When a urethane resin emulsion is used as the synthetic resin emulsion, durability, solvent resistance,
Advantageous are chemical resistance and stain resistance.

[Other Emulsions for Crosslinking Reaction] In the synthetic resin emulsions, in addition to the above-mentioned crosslinking reaction between hydroxyl groups and isocyanate compounds, carbonyl groups and hydrazide groups, carboxylic acids and metal ions, epoxy groups and amines, epoxy groups It is also possible to use an emulsion that forms a cross-linking reaction using a carboxylic acid and aziridine, a carboxylic acid and carbodiimide, a carboxylic acid and oxazoline, an acetoacetate and ketimine, and the like. The cross-linking reaction type emulsion may be a one-component type or a multi-component type of two or more components.

When a crosslinking reaction type emulsion is used as the synthetic resin emulsion, durability, solvent resistance, chemical resistance, stain resistance and the like are advantageous.

In the synthetic resin emulsion, (meth)
Ethylenically unsaturated carboxylic acids such as acrylic acid; α, β-ethylenically unsaturated carboxylic acids such as maleic acid, itaconic acid, crotonic acid, fumaric acid, and citraconic acid; acid anhydrides such as maleic anhydride and itaconic anhydride When a carboxylic acid-containing monomer such as a carboxylic acid-containing monomer is contained, the weight ratio of the monomer to the total weight of the monomer is 5.0% or less, more preferably 2.0% or less, and furthermore 1.0% or less. By limiting to such a range, the stain resistance and the ability to prevent the penetration of contaminants can be improved. If the carboxylic acid-containing monomer exceeds 5.0%, the stain resistance and the ability to prevent the penetration of contaminants tend to decrease, which is not preferable.

The method for producing the synthetic resin emulsion is not particularly limited. For example, as the emulsion polymerization method, it can be produced by batch polymerization, monomer drop polymerization, emulsion monomer drop polymerization, or the like.

As the emulsifier used for the polymerization, it is necessary to use an emulsifier capable of ensuring the stirring stability and the low-temperature stability of the synthetic resin emulsion. The type is appropriately selected from anionic, cationic, nonionic, amphoteric, nonionic-cationic, nonionic-anionic, non-reactive, and reactive, and used alone or in combination. I do. Among them, the use of a reactive emulsifier having an unsaturated double bond is preferable because the water resistance can be improved. Furthermore, the combined use of a nonionic reactive emulsifier and an anionic reactive emulsifier is preferable because it can improve water resistance, stirring stability and low-temperature stability, and can also improve stain resistance.

As the polymerization initiator, ordinary radical initiators can be used, such as persulfates such as ammonium persulfate, a redox initiator comprising a combination of hydrogen peroxide and sodium hydrogen sulfite, Examples thereof include a system in which an inorganic initiator such as iron salt and silver nitrate is mixed, a dibasic acid peroxide such as disuccinic peroxide and diglutaric peroxide, and an organic initiator such as azobisbutyronitrile. The amount of the polymerization initiator is usually 0.01 to 100 parts by weight of the monomer.
It is about 5 parts by weight.

In addition, inorganic salts such as sodium carbonate, potassium carbonate and sodium thiosulfate and organic bases such as triethylamine and triethanolamine may be added to adjust the pH of the emulsion within a range not to impair the effects of the present invention. it can.

(A) In addition to the above-mentioned synthetic resin emulsion, an organic solvent, an inorganic coloring pigment, an organic coloring pigment, an extender pigment and the like which are usually used for a coating material can be added to the aqueous coating material, if necessary. . In addition, plasticizers, preservatives, fungicides, defoamers, thickeners, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, matting agents, ultraviolet absorbers, which do not affect the present invention, Additives such as antioxidants may be used alone or in combination.

Examples of the organic solvent include methanol,
Ethanol, propanol, isopropyl alcohol,
Alcohols such as benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol,
Polyhydric alcohols such as dipropylene glycol, trimethylolethane, glycerin, etc .; ethers such as cellosolve, butyl cellosolve, isobutyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether;
Esters such as trimethyl-1,3-pentanediol monoisobutyrate can be used.

Examples of the inorganic color pigments include titanium oxide, carbon black, ferric oxide (red iron oxide), yellow iron oxide, ocher, ultramarine, and cobalt green. Naphthol,
Pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, quinophthalone and the like can be used.

Examples of extenders include extender pigments such as heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, and barium carbonate.
However, when the present invention is applied to a gloss paint having high gloss, it is necessary to pay attention to the type and the amount of the extender pigment so that the gloss of the formed coating film does not decrease.

The amino group-containing silane coupling agent (B) in the composition of the present invention is an essential component in order to ensure the adhesion when performing recoating.

Examples of the amino group-containing silane coupling agent include γ-aminopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropyldimethylmethoxysilane, γ-
Aminopropyldimethylethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldiethoxysilane, N- (6-aminohexyl)
Aminopropyltrimethoxysilane, N- (6-aminohexyl) aminopropyltriethoxysilane, N-
(Β-aminoethyl) -γ-aminoisobutyltrimethoxysilane, N- (β-aminoethyl) -γ-aminoisobutylmethyldimethoxysilane, γ-aminopropyldiisopropyltrimethoxysilane, γ-aminopropyldiisopropyltriethoxysilane, γ-aminopropylmethylbis (trimethylsiloxy) silane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-phenyl-γ-aminopropyltriethoxy Silane, N-benzyl-γ-aminopropyltrimethoxysilane, N-benzyl-γ-aminopropyltriethoxysilane, 3- (m-aminophenoxy) propyltrimethoxysilane, 3- (m-aminophenoxy) propyl Liethoxysilane, m-aminophenyltrimethoxysilane, m-aminophenyltriethoxysilane, p-aminophenyltrimethoxysilane, p-aminophenyltriethoxysilane, aminophenyltrimethoxysilane, aminophenyltriethoxysilane, γ- Aminopropyltris (methoxyethoxyethoxy) silane, γ-aminopropyltris (trimethylsiloxy) silane, 2-aminoethylaminomethylbenzyloxydimethylsilane, (aminoethylaminomethyl) phenethyltrimethoxysilane, N-vinylbenzyl-γ- Aminolopyrtriethoxysilane,
And the like.

The amino group-containing silane coupling agent is used in an amount of 0.1 to 100 parts by weight of the solid content of the synthetic resin emulsion.
It is added in the range of 0.05 to 3.0 parts by weight. When the amount is less than 0.05 part by weight, sufficient adhesion at the time of recoating cannot be ensured. When the amount is more than 3 parts by weight, viscosity stability when mixing with a low-contamination agent and low-contamination property of a formed coating film. May decrease, which is not preferable.

The modified condensate of the alkoxysilane (C) in the composition of the present invention acts as a low-staining agent, and imparts stain resistance and anti-soiling property to the aqueous coating composition of the present invention. It is an indispensable ingredient.
Further, by being modified, (A) the compatibility with the water-based paint is good, and when it is used for a gloss paint, an effect that a coating film having high gloss can be formed is exhibited. When an unmodified alkoxysilane is used, the compatibility with the water-based paint is poor, causing a problem that foreign matter is generated in the paint and that the gloss of the coating film with gloss paint is reduced.

As the modified condensate of the alkoxysilane (C), a product obtained by modifying the alkoxyl group of the alkoxysilane with a compound containing a polyoxyalkylene group, a compound containing an amino group, a compound containing fluorine, or the like is used.
Among these, an alkoxysilane condensate modified with a polyoxyalkylene group-containing compound is preferably used from the viewpoint of compatibility with the water-based paint.

The production method (C) can be produced by the method described below, but is not limited thereto. As a specific production method of (C), for example, one or more condensates of alkoxysilane are
Examples thereof include a method of performing a transesterification reaction with one or more polyoxyalkylene group-containing substances and a method of performing an addition reaction using a coupling agent described below.

[0049] i) transesterification reaction i.e., the general formula _{^{(R 1 O) 4-a}} -SiR 2 a ( wherein, ^{R 1} represents an alkyl group having 1 to 4 carbon atoms, ^{R 2}
Is an alkyl group, an aryl group, an aralkyl group,
4 represents an alkoxyl group, and a represents an integer of 0 to 2)
(Hereinafter referred to as “a component”)
That. The raw material before the condensation is referred to as “a component monomer”. ) And the general formula ^{_{R 3 - (OC n H 2n}} ) m -R 4 ( wherein, ^{R 3} is a hydrogen atom or an alkyl group, an epoxy group, an acyl group, ^{R 4} is a hydroxyl group, an alkyl group, an alkoxyl group, An epoxy group, an acyl group, a carboxyl group, n is an integer of 1-4, and m is an integer of 1-20)
By transesterification with a polyoxyalkylene chain-containing compound represented by the following formula (hereinafter referred to as “component b”). In particular, in the transesterification reaction, it is necessary to have at least one or more hydroxyl groups at the terminal (this is not the case in the case of an addition reaction using a coupling agent described later). It is important to use the ingredients.

Specifically, as the monomer of the component a,
For example, tetramethoxysilane, tetraethoxysilane,
Tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetra-i-
Butoxysilane, tetra-t-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane,
Ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltributoxysilane, butyltrimethoxylan, butyltriethoxysilane, Butyl tripropoxy silane,
Examples include butyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, and condensates of diethyldibutoxysilane. These can be used alone or as a mixture of plural types.

The alkoxysilyl group of component a has 1 carbon atom.
To 4 are preferable. When the number of carbon atoms exceeds 5, heating at a high temperature is required in the transesterification reaction between the monomer of the component a and the component b. However, since the thermal stability of the component a is inferior, the gel tends to be unusable during the transesterification reaction. The average degree of condensation of the component a is preferably 1 to 20. If the average degree of condensation exceeds 20, handling becomes inconvenient, which is not preferable.

Specific examples of the component b include polyoxyethylene glycol, polyoxyethylene glycol monoalkyl ether, polyoxyethylene-propylene glycol, polyoxyethylene-tetramethylene glycol, polyoxyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl. ether,
Polyoxyethylene diglycolic acid, polyoxyethylene glycol vinyl ether, polyoxyethylene glycol allyl ether, polyoxyethylene glycol diallyl ether, polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkyl Amines and the like. These compounds are
One or a combination of two or more can be selected.

The average molecular weight of the component b is preferably from 150 to 2,000. If the average molecular weight is less than 150, the stability when mixing the low-staining agent obtained by transesterification with the component a into the paint tends to be poor, and excellent gloss is obtained with the gloss paint. Is gone. Conversely, if the average molecular weight of the component b exceeds 2,000, the water resistance and hardness of the cured coating film tend to decrease.

In the above, an example is described in which the ester exchange reaction is carried out after the monomer of the component a is condensed. However, a production method in which the monomer of the component a is transesterified with the component b in advance and then condensed can also be used.

In carrying out the transesterification reaction, a transesterification catalyst (hereinafter referred to as "component c") can be added.

As the component c, for example, organic tin compounds such as dibutyltin dilaurate, dibutyltin malate, dioctyltin dilaurate, dioctyltin malate; phosphoric acid such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, monooctyl phosphate; Phosphate esters; Adducts of epoxy compounds such as propylene oxide, butylene oxide, glycidyl methacrylate, γ-glycidoxypropyltriethoxysilane, and Epikote 828 with phosphoric acid and / or acidic monophosphate esters; organic titanate compounds; Aluminum compound; organic zirconium compound; maleic acid;
Acidic compounds such as adipic acid, azelaic acid, their anhydrides, and paratoluenesulfonic acid; hexylamine; Amines such as N-dimethyldodecylamine;
Curing catalysts such as an alkaline compound such as sodium hydroxide are exemplified.

Such a component c can be used alone or in combination of two or more. Component c is preferably used in an amount of 0.0001 to 5 parts by weight based on 100 parts by weight of component a. When the amount of the component c is 0.0001 parts by weight or less, the contribution to the transesterification reaction is small,
If the amount is more than 1 part by weight, the condensation reaction of the component (a) itself is accelerated, and the stability of the low-contaminating agent is undesirably reduced.

Ii) Addition Reaction by Coupling Agent The low-staining agent in the present invention may be prepared by a method of introducing the component b into the component a by transesterification, or a reaction for binding the component a and the component b in one molecule. It can also be produced by an addition reaction using a coupling agent having a hydrophilic functional group and one or more alkoxysilyl groups (hereinafter referred to as “d component”).

Examples of the reactive functional group of the component d include a vinyl group, an epoxy group, an amino group, an isocyanate group and a mercapto group. Further, the functional group may be bonded to an alkoxysilyl group via a urethane bond, a urea bond, a siloxane bond, an amide bond, or the like.

As the d component, specifically, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyl Triethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane,
N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxy Examples include silane.

The amount of (C) added is 100 parts by weight of the solid content of the synthetic resin emulsion of the water-based coating composition.
In O ₂ conversion in the range of 1.0 to 40.0 parts by weight. When the content of (C) is less than 1.0 part by weight based on 100 parts by weight of the solid content of the synthetic resin emulsion of the water-based paint, the effect of reducing pollution cannot be exhibited. When the amount exceeds 40.0 parts by weight, the viscosity stability of the water-based paint and (B) tends to decrease, and glossiness may be reduced in gloss paint.

Here, in terms of SiO 2, the term “silica (SiO 2) that is obtained by completely hydrolyzing a compound having a Si—O bond such as alkoxysilane or silicate when calcined at 900 ° C. It is represented.

In general, alkoxysilanes and silicates have the property of reacting with water to undergo a hydrolysis reaction to form silanols, and to further cause condensation reactions between silanols or between silanols and alkoxy. When this reaction is performed to the ultimate, silica (SiO 2) is obtained. These reactions are

Embedded image This is a conversion formula of the amount of the remaining silica component based on this reaction formula.

The actual calculation is

(Equation 1) The equation was used.

It is preferable to add (D) a curing catalyst to the aqueous coating composition of the present invention. The addition amount of the curing catalyst is preferably from 0.1 to 10 parts by weight of the curing catalyst based on 100 parts by weight of the aqueous paint. If the amount is less than 0.1 part by weight, the reaction rate becomes slow, and as a result, the effect of low contamination of the cured coating film tends to decrease. If the amount is more than 10 parts by weight, the appearance and durability of the coating film tend to decrease.

Examples of such a curing catalyst include, for example,
Organotin compounds such as dibutyltin dilaurate, dibutyltin malate, dioctyltin dilaurate, dioctyltin malate; phosphoric acid or phosphoric acid esters such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, monooctyl phosphate; propylene oxide, butylene oxide Glycidyl methacrylate, γ-glycidoxypropyltriethoxysilane, Epikote 82
Adducts of epoxy compounds such as 8 with phosphoric acid and / or acidic monophosphate esters; organic titanate compounds;
Organic aluminum compounds; organic zirconium compounds; maleic acid, adipic acid, azelaic acid, acid anhydrides thereof, acidic compounds such as paratoluenesulfonic acid; hexylamine; Examples thereof include amines such as N-dimethyldodecylamine; alkaline compounds such as sodium hydroxide. These curing catalysts can be used alone or in combination of two or more.

These curing catalysts can be added after emulsification and dispersion using an emulsifier. The emulsifier to be used is not particularly limited, but nonionic, anionic and nonionic-anionic emulsifiers can be suitably used.

Further, to the water-based coating composition of the present invention, an alkoxysilane compound as described above as the monomer of the component a may be added within a range not to impair the effects of the present invention.

In the composition of the present invention, since the (C) low-fouling agent reacts with water, it should be avoided to keep the (A) water-based paint containing water for a very long time. Therefore, the composition of the present invention has 2
It is desirable that the composition be treated as a multi-component type paint having more than the components and be mixed at the time of use.

In this case, for example, the first component is (A), the second component is a mixture of (B) and (C); the first component is a mixture of (A) and (B), A mixture of (C) as an eye. Further, when (D) a curing catalyst is contained, (A) is a first component, a mixture of (B), (C), and (D) as a second component; a mixture of (A) and (B) as a first component A mixture of (C) and (D) as a second component; a mixture of (A) and (D) as a first component, (B) as a second component,
A mixture of (C); (A), (B),
The mixture of (D) and (C) as the second component can be used.

The composition of the present invention comprises (A), (B),
(C) If necessary, the pH when (D) is mixed is 9.
It must be 0 or less. By adjusting the pH at the time of mixing to such a range, it is possible to ensure viscosity stability when mixing the water-based paint and the low-staining agent, gloss with gloss paint, and stain resistance of the formed coating film. .

The aqueous coating composition of the present invention can be used for metal, glass, porcelain tile, concrete, siding board,
It can be used for surface finishing of various materials such as extruded plates and plastics, and is mainly used for protection of buildings such as buildings and civil engineering structures. At this time, the aqueous coating composition of the present invention is applied to the final finished surface,
It is possible to apply directly to the base material, or to apply it after applying some surface treatment (base treatment with a sealer, surfacer, filler, etc.), but it is not particularly limited. As a coating method, it can be applied by various methods such as brush coating, spray coating, roller coating, roll coater, flow coater and the like. Further, the surface of the building material can be pre-coated at a factory or the like.

[0073]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention.

[Synthesis of Low-Pollutant] (Synthesis Example 1) Synthesis Example of Alkoxysilane-Modified Condensate 1 An average molecular weight of 750 which is a condensate of tetraethoxysilane
100.0 parts by weight of ethyl silicate condensate P (average molecular weight: 750, silica remaining ratio: 40% by weight) and 106.7 parts by weight of polyoxyethylene glycol # 200 having an average molecular weight of 200 (manufactured by Wako Pure Chemical Industries, Ltd.) Then, after adding 0.02 parts by weight of dibutyltin dilaurate as a catalyst, a deethanolization reaction was carried out at 75 ° C. for 8 hours to synthesize an alkoxysilane-modified condensate 1.

The alkoxysilane-modified condensate 1
The residual silica ratio obtained by calcining at 0 ° C. was 20.9% by weight.

(Synthesis Example 2) Synthesis Example of Alkoxysilane-Modified Condensate 2 100 parts by weight of ethyl silicate condensate P, 81.7 parts by weight of polyoxyethylene glycol monocetyl ether having an average molecular weight of 400 (manufactured by Tokyo Chemical Industry Co., Ltd.) Mix
0.02 parts by weight of dibutyltin dilaurate was added as a catalyst, and an alkoxysilane-modified condensate 2 was synthesized in the same manner as in Synthesis Example 1.

The residual silica ratio of this alkoxysilane-modified condensate 2 was 22.2% by weight.

Synthesis Example 3 Synthesis Example of Alkoxysilane-Modified Condensate 3 100 parts by weight of ethyl silicate condensate Q having an average molecular weight of 900 (average molecular weight of 900, silica remaining ratio of 45% by weight) and polyoxyethylene having an average molecular weight of 1000 385.4 parts by weight of lauryl ether (manufactured by Kao Corporation) were mixed, and 0.02 parts by weight of dibutyltin dilaurate was further added as a catalyst, and an alkoxysilane-modified condensate 3 was synthesized in the same manner as in Synthesis Example 1.

The residual ratio of silica in the alkoxysilane-modified condensate 3 was 11.7% by weight.

[0080]

[Table 1]

[Preparation of paint] A paint was prepared using the synthetic resin emulsion shown in Table 2 with the composition shown in Table 3. Next, as shown in Table 4, a low-contamination agent and the like were blended, and each test was performed.

[0082]

[Table 2]

[0083]

[Table 3]

[0084]

[Table 4]

[Test Method] Viscosity Stability Immediately after mixing the water-based paint and the low-contaminating agent, the viscosity was measured, and the mixture was further left for 1 hour at a temperature of 20 ° C. and a humidity of 65% (hereinafter referred to as “standard state”). After that, the viscosity is measured again. The evaluation is as follows. ：: Increase in viscosity is less than 1.0 Pa · s ×: Increase in viscosity is 1.0 Pa · s or more

Evaluation of Compatibility After mixing the water-based paint and the low-contaminating agent, the mixture was allowed to stand for 1 hour in a standard state, and the presence or absence of generation of foreign substances was confirmed. The evaluation is as follows. ○: No abnormality ×: Foreign matter generated

60 ° specular glossiness The coating composition was applied to a 150 × 120 × 3 mm transparent glass plate with an applicator so that the WET film thickness became 150 μm, and dried and cured under standard conditions for 2 days.
990) 7.6 The gloss value was measured at an angle of 60 degrees according to the specular gloss.

Water resistance 150 × 70 × 3 mm flexible plate, SK # 10
A 00 primer (epoxy resin primer; manufactured by SK Chemical Co., Ltd.) was spray-coated so as to have a dry film thickness of 30 μm, and dried for 8 hours in a standard state. Next, the prepared coating composition was spray-coated so as to have a dry film thickness of 40 μm to prepare a test body. After the prepared test specimens were dried and cured for 7 days under standard conditions, JISK5660 (1995) 4.10
The gloss retention after immersion in water at 20 ° C. for 96 hours was calculated according to the above. The evaluation is as follows. ：: Gloss retention of 90% or more 光 沢: Gloss retention of 80% or more and less than 90% ×: Gloss retention of less than 80%

Rain Streak Contamination An aluminum plate of 300 × 150 × 3.0 mm bent at an angle of 135 ° at one third of the length from above (hereinafter, “exposure plate”) That)
SK # 1000 primer and a dry film thickness of about 30μ
m, and dried under standard conditions for 8 hours. (The exposed plate has a convex surface as the surface.) Next, the prepared coating composition is spray-coated on the exposed plate coated with the primer so that the dry film thickness is about 40 µm.
The specimen was dried under standard conditions for 7 days. The prepared specimen was placed in Ibaraki City, Osaka Prefecture, facing the south side, making the large area vertical, and placing the narrow area on top,
Outdoor exposure was performed, and the presence or absence of rain streak stains after 6 months was visually evaluated. The evaluation is as follows. ◎: No rain streak contamination on vertical surface ○: Slight rain streak contamination on vertical surface ×: Clear streak contamination on vertical surface

Stain resistance to dirt SK # 100 on an aluminum plate of 150 × 75 × 0.8 mm
The No. 0 primer was spray-coated so as to have a dry film thickness of 30 μm, and dried under standard conditions for 8 hours. Next, the prepared coating composition was spray-coated so as to have a dry film thickness of 40 μm to prepare a test body. The prepared test body was dried and cured in a standard state for 7 days, and then, according to JISK5400 (1990) 8.10 stain resistance test, a 15% by weight aqueous dispersion of carbon black was applied to the coating surface with a diameter of 20 mm and a height of 5 mm. Then, the mixture was left in a constant temperature room at 50 ° C. for 2 hours. Thereafter, the film was washed in running water, and the degree of contamination of the coating film surface was visually evaluated. The evaluation is as follows. ◎: No trace ○: Slight trace ×: Clear trace

Adhesion during recoating SK # 10 was applied to a 150 × 70 × 3 mm flexible plate.
The No. 00 primer was spray-coated so as to have a dry film thickness of 30 μm, and was dried under standard conditions for 8 hours. Next, the prepared coating composition was spray-coated so as to have a dry film thickness of 40 μm, and under each condition (standard state 3 days, standard state 7 days,
After curing at 50 ° C. for 3 days and 50 ° C. for 7 days), the same coating composition was spray-coated so that the dry film thickness became 40 μm, and cured under standard conditions for 3 days to obtain a test specimen.
The prepared specimen was evaluated for adhesion in accordance with JIS K5400 8.5.2. The evaluation is as follows. ：: Deficient area is within 5% Δ: Defective area is 5-35% ×: Defective area is 35% or more

[Test Results] Table 5 shows the test results.

[0093]

[Table 5]

(Examples 1 to 5) Good viscosity stability and compatibility when mixed with a low-contaminating agent, high glossiness of the formed coating film, water resistance, rain streak stain resistance, and stain resistance. It was excellent.

(Comparative Example 1) The pH of the paint was high, the viscosity stability could not be ensured when the low-contaminating agent was mixed, and the result was that the rain streaks were inferior. (Comparative Example 2) The amount of the amine compound was larger than the specified amount of the present invention, the viscosity stability when the low-staining agent was mixed could not be ensured, and the water resistance and rain streaks were poor. (Comparative Example 3) When no amine compound was contained, 5
The adhesion at the time of recoating after curing at 0 ° C. for 7 days was reduced. (Comparative Example 4) When the content of the low-staining agent was made smaller than the content of the present invention, the result was inferior in rain streak stainability and dirt penetration resistance. (Comparative Example 5) When the content of the low-contaminating agent was made higher than the content of the present invention, the viscosity stability at the time of mixing the low-contaminating agent could not be ensured, and the adhesion at the time of recoating was poor. Was. (Comparative Example 6) When unmodified ethyl silicate was used as the low-staining agent, the compatibility at the time of mixing with the coating material was poor, and the gloss of the formed coating film was also reduced. In addition, the result was inferior in rain streak stainability and adhesiveness at the time of recoating.

[0096]

The water-based paint composition of the present invention has good viscosity stability and compatibility when the water-based paint and the low-staining agent are mixed, and maintains a high gloss value when applied to a gloss paint. be able to. Further, it is possible to obtain a coating film having significantly improved stain resistance and resistance to penetration of contaminants. Furthermore, the adhesion at the time of performing the overcoating of the paint can also be ensured.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09D 201/08 C09D 201/08

Claims (5)

[Claims] 1. An aqueous coating composition comprising (A) a synthetic resin emulsion as a binder, (B) an amino group-containing silane coupling agent, and (C) a modified condensate of an alkoxysilane.
(B) is 0.05 to 3.0 parts by weight, and (C) is S based on 100 parts by weight of the solid content of the synthetic resin emulsion of (A).
iO ₂ from 1.0 to 40.0 parts by weight is blended in terms of an aqueous low-staining coating composition characterized in that the pH after mixing is 9.0 or less. 2. The synthetic resin emulsion of (A),
The aqueous low-contamination coating composition according to claim 1, wherein the carboxylic acid-containing monomer is contained in a weight ratio of 5.0% or less based on the total weight of the monomer. 3. The modified condensate of (C) alkoxysilane,
The aqueous low-contamination coating composition according to claim 1 or 2, wherein the composition has at least one or more polyoxyalkylene groups. 4. The modified condensate of (C) alkoxysilane,
A modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the repeating unit of the polyoxyalkylene group has 1 to 4 carbon atoms, and the alkoxyl group has 1 to 4 carbon atoms. The aqueous low-contamination coating composition according to claim 1 or 2, wherein 5. The modified condensate of (C) alkoxysilane,
A modified condensate of an alkoxysilane having at least one or more polyoxyalkylene groups and alkoxyl groups, wherein the repeating unit of the polyoxyalkylene group has 2 carbon atoms, and the alkoxyl group has 2 carbon atoms. 3. The aqueous low-contamination coating composition according to claim 1, wherein the ethoxy group is a ethoxy group.