JP2000044836A - Aqueous low-fouling coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having a good viscosity stability and compatibility at the time of mixing both components, capable of forming a coating film excellent in fouling resistance, etc., and useful for surface finish of a material such as a metal by including a modified condensate of an alkoxysilane as a fouling reducing agent in a specific aqueous coating material. SOLUTION: This composition is obtained by combining (A) an aqueous coating material at pH <=8.0 containing a synthetic resin emulsion containing preferably a carboxylic acid-containing monomer in <=5.0% weight ratio based on the total weight of the monomer such as an acrylic resin-based emulsion as a binder with (B) a modified condensate of an alkoxysilane having preferably >=1 polyoxyalkylene groups in an amount of 1.0-40.0 pts.wt. based on 100 pts.wt. of solid content of the synthetic resin emulsion of the component A and expressed in terms of SiO2. The component B is obtained by carrying out transesterification of, e.g. a condensate of tetraethoxysilane with a polyoxyethylene glycol, etc.

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]

SUMMARY OF THE INVENTION However, a WO which merely adds an organosilicate and / or a condensate thereof is disclosed.
In the case of 94/06870, the hydrolysis-condensation reaction which occurs when the organosilicate and / or its condensate is added to the water-based paint cannot be controlled, so that the paint viscosity rapidly increases in a short time, and furthermore, the whole paint Was gelled, and even a normal painting operation could not 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. Thus, simply adding the organosilicate and / or its condensate to the water-based paint will
There was a problem that could not be ignored in practical use.

Accordingly, the problem to be solved by the present invention is that the viscosity stability when the water-based paint and the low-contamination agent are mixed is good, and the compatibility between the water-based paint and the low-contamination agent is good. It can significantly improve stain resistance and the ability to prevent the penetration of contaminants, and when applied to gloss paint, a high-gloss water-based paint, has a high gloss value. An object of the present invention is to provide a water-based low-contamination coating composition that can be used.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve these problems, and as a result, a modified condensate of alkoxysilane is blended as a low-staining agent in a specific water-based paint. As a result, the viscosity stability when mixing the water-based paint and the low-contamination agent is good and does not hinder the coating operation, and the compatibility between the water-based paint and the low-contamination agent is good and aggregates are formed. Without any problem, it is possible to obtain a coating film having excellent stain resistance and resistance to penetration of contaminants, and it has been found that when applied to gloss paint, a coating film having a high gloss value can be obtained. Was completed.

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

1. (A) a water-based paint having a pH of 8.0 or less using a synthetic resin emulsion as a binder and (B) a modified condensate of an alkoxysilane, and a solid content of 100 parts by weight of the synthetic resin emulsion of (A) For
(B) An aqueous low-contamination coating composition comprising 1.0 to 40.0 parts by weight of a modified condensate of alkoxysilane in terms of SiO ₂ .

2. The synthetic resin emulsion (A) contains a carboxylic acid-containing monomer in a weight ratio of 5.0% or less based on the total weight of the monomer. 2. The aqueous low-contamination coating composition according to item 1.

3. (B) 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. (B) the modified condensate of alkoxysilane is a modified condensate of 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; The carbon number of the alkoxyl group is 1 to
4. Or 2. 2. The aqueous low-contamination coating composition according to item 1.

[0015] 5. (B) 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 polyoxyalkylene group has a repeating unit having 2 carbon atoms. 1. An ethylene group, 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.

[0016]

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

The water-based paint (A) constituting the present invention contains a synthetic resin emulsion as a binder, and also contains various pigments and various additives. The pH of the water-based paint is 8.0 or less. Is essential. When the pH is 8.0 or less, good viscosity stability when the aqueous paint and the low-staining agent are mixed is ensured. If it exceeds 8.0, there arises a problem that the viscosity increases in a short time after mixing, and further leads to gelation.

The synthetic resin emulsion used in the water-based paint (A) of the present invention is prepared by not adjusting the pH with a base,
Even if it is performed, it is necessary to keep the pH of the water-based paint (A) so as not to exceed 8.0. If the preparation is not made alkaline, the stirring stability and the low-temperature stability may be reduced. However, by selecting an appropriate dispersant, these stability can be ensured.

In the present invention, the pH of (A) is adjusted to 8.0.
It is thought that the following makes it possible to appropriately suppress the reaction rate of the hydrolysis and condensation of (B) that occurs when (B) is mixed with (A), thereby ensuring the viscosity stability of the coating. Can be

The synthetic resin emulsion used in (A) is not particularly limited as long as the pH of (A) can be adjusted so as not to exceed 8.0. Examples of usable synthetic resin emulsions include acrylic resin emulsions, acrylic silicone resin emulsions, fluororesin emulsions, and urethane resin emulsions.

[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] As the acrylic silicone resin emulsion, a silicon-containing acrylic monomer and another monomer copolymerizable with the silicon-containing acrylic monomer are radically copolymerized. Can be used.

The silicon-containing acrylic monomer is not particularly restricted but includes, 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 other monomers copolymerizable with the silicon-containing acrylic monomer, for example, the monomers 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] As the fluororesin emulsion, 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 in Crosslinking Reaction] In the synthetic resin emulsion, besides the above-mentioned crosslinking reaction by hydroxyl group and isocyanate compound, carbonyl group and hydrazide group, carboxylic acid and metal ion, epoxy group and amine, epoxy group 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 cross-linking reaction type emulsion is used as the synthetic resin emulsion, durability, solvent resistance, chemical resistance, stain resistance and the like are advantageous.

When the synthetic resin emulsion contains a carboxylic acid-containing monomer, its weight ratio is preferably at most 5.0%, more preferably at most 2.0%, based on the total weight of the monomers. Is more preferable. 5.0
%, The stain resistance and the ability to prevent the penetration of contaminants tend to decrease.

The method for producing the synthetic resin emulsion is not particularly limited. For example, the emulsion 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 securing the stirring stability and 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. Of these, the use of a reactive emulsifier can improve water resistance, and is therefore preferable. 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, redox initiators comprising a combination of hydrogen peroxide and sodium hydrogen sulfite, and furthermore, 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 polymerization initiator can be used in an amount of about 0.01 to 5 parts by weight based on 100 parts by weight of the monomer. In addition, inorganic salts such as sodium carbonate, potassium carbonate, and sodium thiosulfate, and organic bases such as triethylamine and triethanolamine can be added to adjust the pH of the emulsion within a range that does not impair the effects of the present invention.

The modified condensate of the alkoxysilane (B) of the present invention acts as a low-staining agent, and is used for imparting stain resistance and prevention of the penetration of contaminants to the aqueous coating composition of the present invention. It is an essential ingredient. Further, by being modified, (A) has good compatibility with the water-based paint, and exhibits an effect of forming a coating film having high gloss when used in gloss paint.
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 (B), those obtained by modifying an alkoxyl group of an alkoxysilane with a polyoxyalkylene group-containing compound, an amino group-containing compound, a fluorine-containing compound or the like are 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 method (B) can be produced by the method described below, but is not limited thereto. As a specific production method of (B), 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.

[0045] 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, diethyldimethylsilane, 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 has been described in which the ester exchange reaction is performed 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.

Examples of the component c include organic tin compounds such as dibutyltin dilaurate, dibutyltin malate, dioctyltin dilaurate, and dioctyltin malate; phosphoric acid such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, and 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.

These c components 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 with Coupling Agent The low-staining agent in the present invention can be prepared by a method of combining component a and component b in one molecule, in addition to the production method of introducing component b into component a by transesterification. 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 for 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-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyltriethoxysilane, β- (3,4
Epoxycyclohexyl) ethyltrimethoxysilane,
N-β (aminoethyl) γ-aminopropylmethyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane And the like.

In the present invention, the water-based paint (A) and (B)
As a method for mixing with (A), (B) can be directly added to (A), or (B) can be mixed with a solvent or a cross-linking agent which can be mixed with (B). It is also possible to add it to (A) later. (B) is added in an amount of 1.0 to _{4 in} terms of SiO2 with respect to 100 parts by weight of the solid content of the synthetic resin emulsion of the aqueous paint (A).
Addition of 0.0 parts by weight is desirable.

Here, the term “SiO 2 conversion” refers to the amount by which a compound having a Si—O bond, such as alkoxysilane or silicate, is completely hydrolyzed, and then calcined at 900 ° C. to form silica (SiO 2). It is represented.

In general, alkoxysilanes and silicates have a property of reacting with water to cause a hydrolysis reaction to form silanols, and to further cause a condensation reaction 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.

The mixing ratio of (A) and (B) of the present invention is
If the amount 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 paint, the effect of reducing pollution cannot be exhibited. If it exceeds 40.0 parts by weight,
The compatibility between (A) and (B) tends to decrease,
Gloss paint causes a decrease in gloss.

To the aqueous 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.

It is preferable to add 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,
Organic tin 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 a surfactant. The surfactant used is not particularly limited, but nonionic, anionic, and nonionic-anionic surfactants can be suitably used.

The aqueous coating composition of the present invention (A) may contain, if necessary, a film-forming aid, an inorganic coloring pigment, an organic coloring pigment, an extender pigment, etc., which are usually used in coating compositions.
Further, a plasticizer, an antiseptic, a fungicide, an antifoaming agent, a leveling agent, a pigment dispersant, an anti-settling agent, which do not affect the present invention,
Additives such as anti-sagging agents, matting agents, ultraviolet absorbers, and antioxidants can be used alone or in combination.

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 or the like), but it is not particularly limited. As the painting method,
The coating can be performed by various methods such as brush coating, spray coating, roller coating, roll coater, and flow coater. Further, the surface of the building material can be pre-coated at a factory or the like.

[0068]

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

(1) Synthesis of Low Contaminant (Synthesis Example 1) Synthesis Example of Alkoxysilane-Modified Condensate 1 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 Synthetic Example 100 parts by weight of ethyl silicate condensate Q having an average molecular weight of 900 (average molecular weight: 900, silica remaining ratio: 45% by weight) and polyoxyethylene having an average molecular weight of 1,000 385.4 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.

[Table 1]

(2) Preparation of paint A paint was prepared using a synthetic resin emulsion as shown in Table 2 according to the formulation in Table 3. Next, a low-pollution agent was added according to the formulation in Table 4.

[Table 2]

[Table 3]

[Table 4]

(3) Test Method Viscosity Stability Immediately after mixing the water-based paint and the low-staining agent, the viscosity was measured, and the mixture was further heated for 1 hour at a temperature of 20 ° C. and a humidity of 65% (hereinafter referred to as “standard state”). After standing, 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-staining agent, the mixture was allowed to stand for 1 hour under standard conditions, and the presence or absence of generation of foreign substances was confirmed. The evaluation is as follows. ○: No abnormality ×: Foreign matter generated

Specular gloss at 60 ° 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, dried and cured under standard conditions for 2 days, and then subjected to JIS K5400
(1990) 7.6 The gloss value at an angle of 60 degrees was measured according to the specular gloss.

Water resistance SK # 1 was added to a 150 × 70 × 3 mm flexible board.
000 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. 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 length from above (hereinafter referred to as “exposure plate”) That)
SK # 1000 primer (epoxy resin primer; manufactured by SK Kaken Co., Ltd.)
It was spray-coated to a thickness of μm and dried under standard conditions for 8 hours. (The exposed plate has a convex surface.) Then, the prepared coating composition was spray-coated on the exposed plate coated with the above-mentioned primer so that the dry film thickness was about 40 μm. It dried and was set as the test body. The prepared specimen was placed in Ibaraki City, Osaka, facing south, with the large area vertical and the narrow area on top, and exposed outdoors. The presence or absence of dirt 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

Resistance to dirt penetration SK # 100 was applied to 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. After the prepared test body was dried and cured for 7 days in a standard state, a 15% by weight aqueous dispersion liquid of carbon black was coated on the coating surface with a diameter of 20 mm and a height of 5 mm according to the JISK5400 (1990) 8.10 stain resistance test. 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

(4) Test Results Table 5 shows the test results.

[Table 5] (Examples 1 to 3 and Example 5) Viscosity stability and compatibility were both good, the formed coating film had a high gloss value, and the results were excellent in raindrop stainability and infiltration prevention of contaminants. (Examples 4 and 6) As an emulsifier, one having no reactivity was used, and the water resistance was slightly lowered. (Example 7) The weight ratio of the carboxylic acid-containing monomer in the synthetic resin emulsion was slightly large, and the stain resistance was slightly lowered.

(Comparative Example 1) The pH of the water-based paint was higher than 8.0, and the results were inferior in viscosity stability, glossiness, and raindrop contamination. (Comparative Example 2) Since the pH of the water-based paint was higher than 8.0 and the silicate was not modified, the viscosity stability,
The results were inferior in compatibility, gloss, raindrop contamination, and ability to prevent permeation of contaminants. (Comparative Example 3) When the silicate was not modified,
The results were inferior in compatibility, glossiness and raindrop contamination. (Comparative Example 4) The amount of the low-contaminating agent added was small, resulting in poor raindrop contamination and poor permeation prevention of contaminants. (Comparative Example 5) The added amount of the low-staining agent was large, and the glossiness was reduced.

[0084]

The water-based paint composition of the present invention has good viscosity stability when mixed with the water-based paint and the low-staining agent, and does not hinder the coating operation. With good compatibility with and without generating aggregates, it is possible to obtain a coating film having excellent stain resistance and resistance to penetration of contaminants, and when applied to gloss paint,
This has the effect that a coating film having a high gloss value can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 183/04 C09D 183/04 F-term (Reference) 4J038 CD091 CG031 CG141 CH031 CH041 CH071 CH121 CH151 CH171 CH201 CH221 CJ011 CJ031 CJ061 CJ081 CJ101 CJ131 DG011 DL052 DL121 GA02 GA06 JA48 JB03 JC13 JC22 JC38 JC39 KA04 MA08 MA10 NA01 NA05 NA23 NA27 PB05 PC02 PC03 PC04 PC06 PC08

Claims (5)

[Claims] (1) A combination of (A) a water-based paint having a pH of 8.0 or less using a synthetic resin emulsion as a binder and (B) a modified condensate of an alkoxysilane, For 100 parts by weight of solid content,
(B) An aqueous low-contamination coating composition comprising 1.0 to 40.0 parts by weight of a modified condensate of alkoxysilane in terms of SiO ₂ . 2. The synthetic resin emulsion of (A), wherein the carboxylic acid-containing monomer is contained in a weight ratio of 5.0% or less based on the total weight of the monomers. Aqueous low-contamination coating composition. 3. The aqueous low-pollution coating composition according to claim 1, wherein the modified condensate of the alkoxysilane (B) has at least one or more polyoxyalkylene groups. 4. The modified condensate of the alkoxysilane (B) is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the number of carbon atoms of the repeating unit of the polyoxyalkylene group is Is 1 to 4, the carbon number of the alkoxyl group is 1 to
3. The aqueous low-contamination coating composition according to claim 1 or 2, wherein 5. The modified condensate of an alkoxysilane (B) is a modified condensate of an alkoxysilane having at least one or more polyoxyalkylene group and alkoxyl group, wherein the number of carbon atoms of the repeating unit of the polyoxyalkylene group is 3 is a polyoxyethylene group having 2 carbon atoms, and the alkoxyl group is an ethoxy group having 2 carbon atoms.