JP2003238272A - Method of producing colored cement roof tile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing a colored cement roof tile which has excellent weatherability, resistance to hot water, coated film hardness or the like and exhibits excellent long-term durability. <P>SOLUTION: An undercoating material containing an acrylic emulsion resin having a gel fraction of ≥50% is coated on the surface of an uncured cement roof tile, and after drying the coated film, the uncured cement roof tile is subjected to steam curing. Thereafter, a topcoating material containing (A) an aqueous dispersion of an organic-inorganic composite resin, which is obtained by neutralizing a hydrolysis-condensation reaction product of (a) 100 parts by mass of an organosilane having general formula: R<SP>1</SP><SB>n</SB>Si(OR<SP>2</SP>)<SB>4-n</SB>or its partial hydrolysis-condensation product and (b) 5 to 200 parts by mass of a silyl group- containing vinyl-based resin containing a hydrolyzable silyl group or a silyl group with a silicon atom bonded with a hydroxy group and having an acidic number of 20 to 150 mgKOH/g and adding water, (B) a hydrolyzable and condensable alkoxysilane having an amino group, and (C) a compound with an epoxy group having reactivity to the amino group in the component (B) in its molecule is coated and baked/hardened. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a colored cement roof tile, and more particularly to a method for producing a colored cement roof tile having excellent weather resistance, warm water resistance, coating film hardness and the like and long-term durability.

[0002]

2. Description of the Related Art In recent years, with the prefabricated housing and cost reduction, the use of cement roof tiles is rapidly increasing in place of conventional Japanese roof tiles and Western roof tiles due to the advantages of workability and manufacturing cost. It is expected that demand will continue to grow.

Cement roof tiles are generally made by mixing cement, reinforcing fibers, aggregates, etc., adding water, mixing and stirring the resulting kneaded product into a mold of a predetermined shape, and dehydrating under pressure. It is produced by molding and curing, and such a cement roof tile may be used as it is, but recently, it is mostly colored and used for the purpose of enhancing the appearance.

As a coloring method, a method of applying a colored coating material made of a polymer material on the surface of a hardened cement roof tile is generally used. However, such a polymer material has a drawback that the baking temperature is high and the cost of raw materials is also high, and further, a color fading phenomenon or a peeling phenomenon often occurs, which is not satisfactory.

Regarding the above-mentioned colored cement roof tile,
In order to prevent efflorescence and discoloration during curing and to impart durability, solvent-based paint or water-based paint may be applied as a sealer and an undercoat paint. In this case, it is difficult to prevent efflorescence unless a paint having the ability to withstand the curing conditions of cement roof tiles is selected, and the adhesiveness with the base material is reduced and blisters, cracks,
Problems such as peeling may occur. As described above, the conventional colored coating method for cement roof tiles and the used coating materials have various defects in terms of performance and application.

A coating film having a binder of an organic-inorganic composite resin obtained by subjecting an organosilane and / or its hydrolytic condensate to a hydrolytic condensation reaction of a vinyl resin containing a silyl group is excellent in weather resistance. In addition, unlike a coating film in which an organopolysiloxane-based inorganic resin is used as a binder, cracks are less likely to occur, and therefore the coating composition in which the organic-inorganic composite resin is used as a binding component is attracting attention as a topcoat paint. Is becoming more common.

[0007]

The present invention has been made in order to solve the problems of the prior art, and is excellent in weather resistance, warm water resistance, coating film hardness and the like, and excellent in long-term durability performance. It is intended to provide a method for producing a colored cement roof tile.

[0008]

Means for Solving the Problems As a result of various studies conducted by the present inventors in order to achieve the above-mentioned objects, an undercoat containing a specific acrylic emulsion resin and a colorant on the surface of an uncured cement roof tile. Apply paint, dry the coating,
After steam curing of uncured cement, by applying a topcoat paint containing a specific organic-inorganic composite resin aqueous dispersion and a specific curing agent, and baking and curing, weather resistance, warm water resistance,
The present invention has been completed by finding that a colored cement roof tile having excellent coating film hardness and the like and long-term durability can be obtained.

That is, the method for producing a colored cement roof tile according to the present invention has a glass transition temperature of 20 to 1 on the surface of the uncured cement roof tile.
After coating an undercoat paint containing an acrylic emulsion resin and a colorant having a gel fraction of 50% or more at 00 ° C and drying the coating film, the uncured cement roof tile is steam-cured, and then (A) (a). General formula R ¹ _n Si (OR ² ) _4-n (wherein
R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is 1 to 1 carbon atoms.
5 is an alkyl group, and n is 1 or 2. 100 parts by mass of organosilane and / or a partial hydrolyzed condensate thereof and (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20 to 150 mgKOH. / G of silyl group-containing vinyl-based resin 5 to 200 parts by mass of the hydrolysis-condensation reaction product is neutralized with a neutralizing agent, water is added to obtain an organic-inorganic composite resin aqueous dispersion, (B) amino A hydrolytic condensation-reactive alkoxysilane having a group and (C) a top-coat paint containing a compound having an epoxy group in the molecule which has reactivity with the amino group of the component (B) is applied and baked and cured. It is characterized by

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. As the uncured cement roof tile used in the present invention, for example, cement, reinforcing fibers, aggregates, etc. are mixed, water is added, and the kneaded product obtained by mixing and stirring is put into a mold of a predetermined shape, and pressure dehydration is performed. An example of the uncured cement roof tile that is molded and primary cured is not limited by the manufacturing method thereof.

The undercoat paint used in the present invention contains an acrylic emulsion resin. This acrylic emulsion resin, for example, with an ethylenically unsaturated carboxylic acid monomer,
Alkyl ester of acrylic acid or methacrylic acid,
A mixture of unsaturated monomers in combination with one or more selected from the group consisting of vinyl aromatic compounds, acrylonitrile, methacrylnitrile, saturated carboxylic acid vinyl esters, vinyl halides, butadiene and ethylene is used as an emulsifier. Obtained by emulsion polymerization in the presence.

In the present invention, the glass transition temperature (hereinafter, Tg
Is 20 to 100 ° C, preferably 40 to 80 ° C, and the gel fraction is 50% or more, preferably 75 to 80.
% Or more acrylic emulsion resin is used. Such an acrylic emulsion resin has excellent curing resistance. Tg of acrylic emulsion resin is 20
If the temperature is lower than 0 ° C, the dry coating film may be melted and eluted due to heat during curing, or a problem such as blocking is likely to occur. Conversely, if the Tg of the emulsion polymer is higher than 100 ° C, This is not preferable because defective film formation during drying tends to occur. Further, when the gel fraction of the acrylic emulsion resin is less than 50%, the dried coating film is melted and eluted by heat during curing, and efflorescence due to alkali from the base is likely to occur, which is preferable. Absent.

The acrylic emulsion resin used in the present invention preferably has a silyl group. As such a silyl group-containing acrylic emulsion resin,
For example, from the group consisting of ethylenically unsaturated carboxylic acid monomers and alkyl esters of acrylic or methacrylic acid, vinyl aromatic compounds, acrylonitrile, methacrylonitrile, saturated carboxylic acid vinyl esters, vinyl halides, butadiene and ethylene. 1 chosen
Or a mixture of two or more kinds of unsaturated monomers, and γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ A silyl group-containing unsaturated monomer such as methacryloxypropylmethyltriethoxysilane and γ
-Glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N
In the presence of an emulsifier, a mixture containing one or more selected from the group consisting of silane coupling agents containing a glycidyl group or an amino group such as -β (aminoethyl) γ-aminopropylmethyltrimethoxysilane Obtained by emulsion polymerization.

This silyl group-containing acrylic emulsion resin also has a Tg of 20 to 100 ° C., preferably 40.
~ 80 ° C, gel fraction 50% or more, preferably 7
5 to 80% or more is used. Such a silyl group-containing acrylic emulsion resin is excellent in curing resistance, and by using such a silyl group-containing acrylic emulsion resin, the adhesion with the topcoat paint used in the present invention is improved, which is preferable. .

The undercoat paint used in the present invention contains a colorant. Typical examples of the colorant include general inorganic pigments, but depending on the color, an organic pigment having alkali resistance and weather resistance may be used.
For example, in the case of coloring black, carbon black, iron oxide, etc., in the case of coloring red, valgate, etc., in the case of coloring green, chrome oxide, etc., in the case of coloring blue, phthalocyanine blue, etc., white. For coloring, titanium dioxide or the like can be used. The color pigments are not limited to these, and color pigments that are commonly used in paints can be used.

The color pigment is preferably blended in the undercoat paint in a proportion of 0.1 to 15% by mass, and the blending within this range allows sufficient coloring. Undercoat paint used in the present invention, the acrylic emulsion resin or silyl group-containing acrylic emulsion resin described above, in addition to the colorant, an organic solvent, a filler, a dye, further, a curing accelerator,
It may contain various additives such as a thickener and a pigment dispersant.

Next, the top coating material used in the present invention will be described. The top coating used in the present invention is (A) (a)
Formula R ¹ _n Si (OR ²⁾ in _4-n (wherein, R ¹ is an organic group having 1 to 8 carbon atoms, R ² is an alkyl group having 1 to 5 carbon atoms, n represents 1 or 2 And (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20-1
50 mgKOH / g silyl group-containing vinyl resin 5-2
The hydrolysis-condensation reaction product with 00 parts by mass is neutralized with a neutralizing agent,
Organic-inorganic composite resin aqueous dispersion obtained by adding water,
It contains (B) an alkoxysilane capable of undergoing a hydrolytic condensation reaction having an amino group, and (C) a compound having in its molecule an epoxy group having reactivity with the amino group of the component (B).

The organic-inorganic composite resin aqueous dispersion of the component (A) used in the present invention is (a) the general formula R ¹ _n Si (O).
R ² ) _4-n (in the formula, R ¹ is an organic group having 1 to 8 carbon atoms, R ² is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2). 100 parts by mass of organosilane and / or its partially hydrolyzed condensate and (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20 to 150 mgKOH / g.
It is obtained by neutralizing the hydrolysis-condensation reaction product of the silyl group-containing vinyl resin of 5 to 200 parts by mass with a neutralizing agent and adding water.

The general formula R ¹ _n Si (OR of the above-mentioned component (a) is
² ) In _4-n , examples of the organic group represented by R ¹ include an alkyl group, a cycloalkyl group, an aryl group, and a vinyl group. The alkyl group may be linear or branched, and examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, and i.
Examples include —propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group, and octyl group. Preferred alkyl groups have 1 to 4 carbon atoms.

Preferred examples of the cycloalkyl group include a cyclohexyl group, a cycloheptyl group and a cyclooctyl group. Examples of the aryl group include a phenyl group. Each of the above functional groups may optionally have a substituent. Examples of such a substituent include a halogen atom (for example, a chlorine atom,
Examples thereof include bromine atom, fluorine atom, (meth) acryloyl group, mercapto group and alicyclic group.

The alkyl group represented by R ² may be linear or branched, and examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group,
Examples thereof include n-butyl group, i-butyl group, s-butyl group, t-butyl group and pentyl group. Preferred alkyl groups have 1 to 2 carbon atoms.

Specific examples of the organosilane represented by the above general formula R ¹ _n Si (OR ² ) _4-n include, for example, methyltrimethoxysilane, methyltriethoxysilane,
Ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane,
i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3 3-trifluoropropyltriethoxysilane, cyclohexyltrimethoxysilane, γ
-Methacryloxypropyltrimethoxysilane, γ-
Methacryloxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane , Diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, and dimethyldipropoxysilane. Preferred are methyltrimethoxysilane, methyltriethoxysilane, and dimethyldimethoxysilane. These organosilanes may be used alone or in combination of two or more.

The component (a) may be a partial hydrolyzed condensate of the above organosilane. The polystyrene reduced mass average molecular weight of the partially hydrolyzed condensate is, for example,
300 to 5000, preferably 500 to 3000 is suitable. By using a condensate having such a molecular weight, a coating film having good adhesion can be obtained without deteriorating storage stability. Further, the partially hydrolyzed condensate of organosilane is a —OH group or —O bonded to a silicon atom.
It is suitable to have one or more, preferably 3 to 30, R ² groups.

Specific examples of such condensates include commercially available products KR-211, KR-21 manufactured by Shin-Etsu Chemical Co., Ltd.
2, KR-213, KR-214, KR-216, KR
-218; TSR-145, TS manufactured by Toshiba Silicone Co., Ltd.
R-160, TSR-165, YR-3187 etc. can be mentioned.

Regarding the above-mentioned component (a) used in the present invention, the organosilane and / or its partial hydrolyzed condensate of the general formula R ¹ _n Si (OR ² ) _{4-n having} an n value of 1 and an n value of When a mixture having a mass ratio of 50:50 to 100: 0, preferably 60:40 to 95: 5, with the organosilane of 2 and / or its partial hydrolysis-condensation product is used, it is stable during the hydrolysis-condensation reaction. And a coating film having good crack resistance is obtained.

The above-mentioned component (b) used in the present invention comprises at least one hydrolyzable silyl group at the terminal or side chain of the vinyl resin, or at least one silyl group having a silicon atom bonded to a hydroxyl group in one resin molecule. , Preferably two or more,
Further, it is a vinyl resin having an acid value of 20 to 150 mgKOH / g and a molecular weight of, for example, about 1,000 to 50,000.

The above silyl group has the general formula --SiX.
_P (R ³ ) _(3-P) (In the formula, X is an alkoxy group, an acyloxy group, a halogen group, a ketoximate group, a mercapto group,
It is a hydrolyzable group such as an alkenyloxy group or a phenoxy group or a hydroxyl group, R ³ is hydrogen or a monovalent hydrocarbon group such as an alkyl group having 1 to 10 carbon atoms, an aryl group or an aralkyl group, and P is 1 Is an integer of ˜3. ).

The silyl group-containing vinyl resin is, for example, represented by the general formula (X) _P (R ³ ) _(3-P) Si--H (wherein X, R ³
And p have the same meaning as above. ) And a vinyl-based resin having a carbon-carbon double bond are reacted according to a conventional method.

As the above-mentioned hydrosilane compound,
Representative examples thereof include methyldichlorohydrosilane, methyldiethoxyhydrosilane, and methyldiacetoxyhydrosilane. The amount of the hydrosilane compound used in producing the silyl group-containing vinyl resin is preferably a molar amount that is 0.5 to 2 times the number of carbon-carbon double bonds contained in the vinyl resin. .

The above vinyl resin contains a carboxylic acid such as (meth) acrylic acid, itaconic acid, fumaric acid or an acid anhydride such as maleic anhydride as an essential monomer unit,
Further, (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylic acid, acrylonitrile, styrene, It is a copolymer containing a vinyl-based monomer selected from the group consisting of α-methylstyrene, vinyl acetate, vinyl propionate, etc. as a comonomer unit. However, allyl (meth) acrylate, diallyl phthalate, etc. are produced at the time of production of the copolymer. By radical copolymerization,
It is possible to introduce a carbon-carbon double bond for the hydrosilylation reaction into the vinyl resin.

The acid value of the resulting vinyl resin is 20.
~ 150 mg KOH / g, preferably 50-120 mg
It is necessary to include the above-mentioned carboxylic acid or acid anhydride in the constituent monomers of the copolymer so as to obtain KOH / g. When the acid value of the vinyl resin is less than 20 mgKOH / g, the storage stability of the resulting aqueous dispersion becomes poor, and conversely, when the acid value of the vinyl resin exceeds 150 mgKOH / g, the water resistance of the resulting coating film is low. , Because the hot water resistance deteriorates,
Neither is preferable.

As another method for producing the above silyl group-containing vinyl resin, a vinyl monomer containing the above carboxylic acid or acid anhydride, 2-hydroxyethyl (meth) acrylate, and 2-hydroxypropyl ( Hydroxyl group-containing monomers such as (meth) acrylate and 2-hydroxyvinyl ether, and γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, β- (meth) acryloxyethyltrimethoxysilane. , Β- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane, γ- (meth)
Acryloxypropylmethyldipropoxysilane, γ-
There is also a method of radical polymerization with a silyl group-containing vinyl compound such as (meth) acryloxybutylphenyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, and γ- (meth) acryloxypropyldiethylmethoxysilane. Specific examples of these silyl group-containing vinyl resins include, for example, Kaneka Zemurask manufactured by Kanegafuchi Chemical Industry Co., Ltd., which is a commercially available product.

Next, a method for producing the organic-inorganic composite resin aqueous dispersion of the component (A) used as the main component in the present invention will be described. First, water and a catalyst are further present in the mixture of the above-mentioned components (a) and (b) to cause hydrolysis and condensation reactions. The mixing ratio of the component (a) and the component (b) is 5 parts of the component (b) with respect to 100 parts by mass of the component (a).
It is suitable that the amount is ˜200 parts by mass, preferably 10 to 150 parts by mass.

When the amount of the component (b) is less than 5 parts by mass, the appearance, crack resistance, frost damage resistance, alkali resistance and the like of the resulting coating film deteriorate, and conversely the amount of the component (b) compounded is 2%.
If it exceeds 100 parts by mass, the weather resistance and stain resistance of the resulting coating film deteriorate, which is not preferable.

The amount of water added to the above mixture of the components (a) and (b) depends on the amount of the hydrolyzable groups initially present in the mixture of the components (a) and (b). Preferably 4
5 to 100%, more preferably 50 to 90%, which is an amount sufficient to cause a hydrolysis and condensation reaction, and specifically 0.45 to 1.0 of the total number of hydrolyzable groups in the above mixture.
It is suitable that the amount is twice, preferably 0.5 to 0.9 times the number of moles. The reason why 45% or more is preferable here is that the storage stability is good when it becomes an organic-inorganic composite resin aqueous dispersion (emulsion), and it is possible to form a highly transparent film when used in a paint. This is because.

Examples of the catalyst to be added to the mixture of the above components (a) and (b) include inorganic acids such as nitric acid and hydrochloric acid, and organic acids such as acetic acid, formic acid and propionic acid. The amount of the catalyst added is appropriately such that the pH of the above mixture becomes 3 to 6. For the hydrolysis reaction, the mixture of the component (a) and the component (b) was added in the presence of water and a catalyst to
A method of reacting at 0 to 80 ° C., preferably 45 to 65 ° C. for 2 to 10 hours with stirring is suitable, but the method is not limited to this.

The hydrolysis-condensation reaction of the components (a) and (b) can be carried out in one step as described above, but from the viewpoint of storage stability of the product, It is preferable to react in two stages. That is, as the first step, in the presence of water and a catalyst, 40% of the hydrolyzable group initially present in the mixture of the component (a) and the component (B) was used.
The reaction is carried out at 40 to 80 ° C., preferably 45 to 65 ° C. for 1 to 8 hours with stirring so that ˜80%, preferably 45 to 70%, undergoes a hydrolytic condensation reaction.

As the second step, following the first step, water and trialkoxyborane such as trimethoxyborane and triethoxyborane, tri-n-butoxyethyl acetate zirconium, di-n-butoxy (ethyl acetate) zirconium, Tetotarakis (ethyl acetate)
Zirconium chelate compounds such as zirconium, titanium diisopropoxybis (acetylacetate) titanium, diisopropoxybis (ethyl acetate) titanium chelate compounds, monoacetylacetate bis (ethylacetoacetate) aluminum, diisopropoxyethylacetoacetate aluminum An organometallic compound catalyst such as an aluminum chelate compound is added to cause a hydrolysis and a condensation reaction. The trialkoxyborane and the organometallic compound catalyst used in the second step can accelerate the condensation reaction and improve the appearance, weather resistance, stain resistance, hot water resistance and the like of the coating film.

The amount of water added in the second stage is 45 to 100%, preferably 50 to 90% of the hydrolyzable groups initially present in the mixture of the components (a) and (b). Is an amount sufficient for the hydrolysis and condensation reaction. The amount of the catalyst added in the second step is 0.001 based on 100 parts by mass of the total amount of the reaction product obtained in the first step and the unreacted components (a) and (b). ˜5 parts by mass, preferably 0.005 to 2 parts by mass. The hydrolysis-condensation reaction in the second step is 40 to 40 as in the first step.
It is suitable to react at 80 ° C. for 2 to 5 hours.

The hydrolysis-condensation reaction product is in a solution state due to the alcohol content produced in the reaction, or the alcohol content and an organic solvent described later added as necessary. A neutralizing agent was added to the solution of the organic-inorganic composite resin, which is the reaction product thus obtained, to uniformly disperse the solution,
After neutralization, water is added, or a neutralizing agent and water are added at the same time, and the mixture is forcibly dispersed by stirring to obtain an aqueous dispersion (emulsion).

The amount of the neutralizing agent is such that 50 to 100%, preferably 70 to 100% of the acid groups in the organic-inorganic composite resin as a reaction product are neutralized so that a stable emulsion can be obtained. Appropriate. In addition, as a neutralizing agent, triethylamine, triethanolamine, dimethylethanolamine, monoethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, morpholine, etc. are mentioned as a typical thing.

The amount of water added after the neutralization is arbitrarily determined in consideration of the coating workability of the coating material, but it is usually an amount such that the solid content of the coating composition is 10 to 70% by mass. Is. In addition, in the organic-inorganic composite resin aqueous dispersion thus obtained, the alcohol content produced by the above-mentioned hydrolysis condensation reaction remains. Therefore, if the aqueous dispersion is used as it is as a coating composition, the amount of volatile organic components (VOC) increases, so it is preferable to remove the alcohol content under reduced pressure according to a conventional method.

The component (B) used in the present invention is an alkoxysilane having an amino group in the molecule and capable of undergoing a hydrolytic condensation reaction, and specifically, it is represented by the general formula (R ⁶ —NH—R ⁵ —) _n Si (OR ⁴ ) _4-n (In the formula, R ⁴ is an alkyl group having 1 to 5 carbon atoms, and R ⁵
Is an alkylene group having 1 to 5 carbon atoms, R ⁶ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an aryl group having 6 to 8 carbon atoms, or a substituted or unsubstituted group. It is a substituted amino group, and n is 1 or 2. )
The amino group-containing alkoxysilane represented by is preferably used.

The alkyl group as R ⁴ may be linear or branched, and examples thereof include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group and i-butyl group. , S-butyl group, t-butyl group, pentyl group. Preferred alkyl groups have 1 to 2 carbon atoms. The alkylene group as R ⁵ may be linear or branched, and examples thereof include a methylene group, an ethylene group and a propylene group.

The alkyl group as R ^{6 is the same} as in the above R ⁴ . Examples of the cycloalkyl group as R ⁶ include a cyclohexyl group and a cycloheptyl group. The aryl group as R ⁶ may be, for example, a phenyl group. Further, examples of the amino group as R ⁶ include those in which one or both of hydrogen atoms in the amino group are substituted with the above alkyl group having 1 to 5 carbon atoms.

Examples of the amino group-containing alkoxysilane represented by the above general formula include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane and N- (β-aminoethyl) -γ-aminopropyltrisilane. Methoxysilane, N- (β-aminoethyl) -γ-
Aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldiethoxysilane, N-cyclohexyl γ-aminopropyltrimethoxysilane, N-cyclohexyl-γ-aminopropyltriethoxysilane, γ -(2-aminoethyl) -aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane, γ-
Anilinopropyltrimethoxysilane can be mentioned.

The amount of the alkoxysilane which is the component (B) is preferably 0.5 to 100 parts by mass of the solid content (organic-inorganic composite resin) of the aqueous dispersion of the organic-inorganic composite resin which is the component (A). 30 parts by mass, more preferably 2 to 15 parts by mass is suitable. When the amount of component (B) is less than the above range, the curability and stain resistance of the resulting coating film tend to deteriorate, and conversely, when it is too large, the hot water resistance and crack resistance deteriorate. Tend.

The component (C) used in the present invention is a compound having in its molecule an epoxy group having reactivity with the amino group in the component (B). As these compounds, epoxy group-containing alkoxysilanes, alkyl glycidyl ethers and esters, cycloepoxy compounds, bisphenol AF-based low molecular weight epoxy resins, or emulsions thereof can be used.

Specifically, γ-glycidoxypropyltrimethyloxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ -Glycidoxypropyltriisopropenyloxysilane, γ-glycidoxypropyltriiminooxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, γ-isonanoatepropyltriisopropenyloxysilane With glycidol, butyl glycidyl ether, polyoxyethylene glycidyl ether, Cardura E (trade name, manufactured by Shell Co.), butylphenyl glycidyl ether, Epicoat 815, 828, 834 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), and the like. these Emulsion is a typical example. Among the above epoxy group-containing compounds, when the epoxy group-containing alkoxysilane compound having a hydrolyzable silyl group is used, the curability of the coating film is improved, and the heat resistance,
It is preferable because alkali resistance and the like are improved.

The blending amount of the component (C) is preferably the total number of epoxy groups of the epoxy group-containing compound with respect to the total number of active hydrogens of amino groups of the amino group-containing alkoxysilane compound which is the component (B). The amount is preferably 0.1 to 2.0 times, more preferably 0.2 to 1.2 times.

When the amount of the epoxy group-containing compound as the component (C) is less than the above range, the hot water resistance of the resulting coating film tends to be poor, and conversely, when it is more than the above range, the coating film is too large. Weather resistance, crack resistance, etc. tend to deteriorate. The amino group-containing alkoxysilane compound which is the component (B) and the epoxy group-containing compound which is the component (C) are mixed with the aqueous dispersion of the component (A) and dispersed before use, to be used.

The above components (B) and (C) act as a curing agent, the amino group in the component (B) reacts with the epoxy group in the component (C), and the silyl group in the component (B). The group, and further, the silyl group in the component (C) (only when present) undergoes a hydrolytic condensation reaction with the silyl group remaining in the organic-inorganic composite resin in the component (A), resulting in hot water resistance, alkali resistance, A cured coating film having excellent weather resistance, stain resistance, solvent resistance and the like is formed.

The top coating composition used in the present invention comprises the above-described aqueous dispersion of the organic-inorganic composite resin of the component (A) which is the main component and the amino group-containing alkoxy which is the component (B) of the curing agent. A silane compound and an epoxy group-containing compound which is the component (C) as a main component, and further, if necessary, water, an organic solvent and a filler for improving the storage stability and coating workability of the coating composition, It is composed of a dye and a mixture of various additives such as a curing accelerator, a thickener, a pigment dispersant and the like.

Examples of the organic solvent include alcohols such as methanol, ethanol, propanol and butanol, alcohol ethers such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, and hydrophilic organic solvents such as acetone and methyl ethyl ketone. A solvent or a mixed organic solvent thereof with a hydrophobic organic solvent for various coating materials such as toluene, xylene, ethyl acetate and butyl acetate can be used.

These organic solvents may be blended as a solvent so that the reaction can occur homogeneously during the production of the organic-inorganic composite resin aqueous dispersion which is the component (A). The content of the organic solvent is preferably 0 to 0 in the coating composition.
20% by mass, more preferably 0 to 10% by mass is suitable.

As the above-mentioned filler, usual inorganic / organic dyes and pigments can be used. Specifically, titanium oxide, zinc sulfide, zinc white, lead white, lithopone, carbon black, oil smoke, dark blue, phthalocyanine blue, ultramarine blue, carmine FB, yellow lead, zinc yellow, Hansa yellow, ocher,
Representative examples include red iron oxide, inactive-containing azo dyes, and the like. The content of the filler is preferably 0 to 70% by mass, more preferably 0 to 50% by mass, based on the solid content of the coating composition.

The top coat used in the present invention may be a clear paint or an enamel paint to produce a good roof tile, but the top coat is preferably a color clear paint. The color clear paint contains the above-mentioned inorganic / organic dyes and pigments in a proportion of about 0.01 to 15% by mass based on the resin solid content. If the amount of this inorganic / organic dye / pigment is less than 0.01% by mass, a sufficient change in color tone cannot be obtained, and conversely, if it exceeds 15% by mass, the transparency of the formed coating film will decrease and the depth There is a tendency that a certain change in color tone cannot be obtained. Particularly, the amount of the inorganic / organic dye / pigment is preferably about 0.05 to 10% by mass.

In the method for producing a cement roof tile of the present invention, the above-mentioned undercoat paint is applied to the surface of the above-mentioned uncured cement roof tile by a usual coating method such as brush, spray, roll coater, flow coater, shower coater and dipping. After drying the coating film according to a usual drying method, the uncured cement roof tile is steam-cured. As an example of this steam curing, as the initial curing, the temperature is raised to 60 ° C. at a heating rate of 20 ° C./hour, and 5
Hold for time, then cool to room temperature.

Then, the above-mentioned top coating composition is applied to the surface of the colored cement roof tile by a usual coating method such as a brush, a spray, a roll coater, a flow coater, a shower coater, dipping, etc., and by a usual baking method, for example, at 300 ° C. or lower. Bake at temperature to form a cured coating.

[0060]

EXAMPLES The present invention will be specifically described below with reference to examples, examples and comparative examples. In addition, in a reference example, an Example, and a comparative example, "part" and "%" are "mass part" and "mass%", respectively.

<Preparation of Acrylic Emulsion Paint 1> While stirring 80 parts of an acrylic emulsion resin having a glass transition temperature of 75 ° C. and a gel fraction of 80%, a film forming aid (2,2,4-trimethyl-1, 3-Pentanediol monoisobutyrate) 2 parts, water 12.4 parts, neutralizer (50% aqueous solution of dimethylaminoethanol) 0.5 parts, thickener (obtained from Rohm and Haas Japan KK) Primal AS which is an alkali swelling type thickener
E-60) 5 parts of an aqueous solution and 0.1 part of a defoaming agent (Fomaster VL, which is a silica-silicone defoaming agent available from San Nopco Co., Ltd.) were added, and the mixture was stirred for 30 minutes, and 1% of a coloring agent was added thereto. Was added and colored to obtain acrylic emulsion paint 1.

The above-mentioned colorant is ion-exchanged water 17.
7 parts, thickener (Natrazole 250HR available from Hercules Japan KK) 0.2 parts, dispersant (OROTAN 731DP available from Rohm and Haas Japan KK) 5 parts, wetting dispersant (Daiichi Kogyo) Neo Neugen 140 available from Pharmaceutical Co., Ltd.
A) 0.5 part, carbon black (Asahi # 50 available from Asahi Carbon Co., Ltd.) 9 parts, titanium dioxide (Taipec CR-97 available from Ishihara Sangyo Co., Ltd.) 10
Parts, barium sulfate (precipitating barium sulfate # 100 available from Sakai Chemical Industry Co., Ltd.) 57.5 parts, and antifoaming agent (Nopco 8034 available from San Nopco Ltd.)
It was obtained by mixing 1 part, adding 30 parts of glass beads therein, and stirring with a disperser until the particle size became 20 μm or less with a particle gauge.

<Preparation of Acrylic Emulsion Paint 2> While stirring 80 parts of a silyl group-containing acrylic emulsion resin having a glass transition temperature of 75 ° C. and a gel fraction of 80%, a film forming aid (2,2,4-trimethyl) was added thereto. -1,3-pentanediol monoisobutyrate) 2 parts, water 12.4 parts, a neutralizing agent (50% aqueous solution of dimethylaminoethanol) 0.
5 parts, 5 parts thickener (primal ASE-60, which is an alkali-swelling thickener available from Rohm and Haas Japan Co., Ltd.) aqueous solution, and antifoaming agent (silica silicone defoamer available from San Nopco Co., Ltd.) Fomaster VL, which is a foaming agent, is added in an amount of 0.1 part and stirred for 30 minutes, and a coloring agent (the same as that used in the preparation of the acrylic emulsion paint 1 above) is added thereto in a proportion of 1%. Then, it was colored to obtain acrylic emulsion paint 2.

<Preparation of Acrylic Emulsion Paint 3> While stirring 80 parts of an acrylic emulsion resin having a glass transition temperature of 30 ° C. and a gel fraction of 40%, a film forming aid (2,2,4-trimethyl-1, 3-Pentanediol monoisobutyrate) 2 parts, water 12.4 parts, neutralizer (50% aqueous solution of dimethylaminoethanol) 0.5 parts, thickener (obtained from Rohm and Haas Japan KK) Primal AS which is an alkali swelling type thickener
E-60) 5 parts of an aqueous solution and 0.1 part of a defoaming agent (Fomaster VL, which is a silica-silicone defoaming agent available from San Nopco Co., Ltd.) are added, and the mixture is stirred for 30 minutes, to which a colorant (the above-mentioned is added. The same as used in the preparation of acrylic emulsion paint 1) was added at a ratio of 1% and colored to prepare acrylic emulsion paint 3.

<Preparation of silyl group-containing vinyl resin solution>
To a reactor equipped with a reflux condenser and a stirrer, 50 parts of diethylene glycol monobutyl ether and 50 parts of n-butanol were added and heated to 100 ° C while stirring. Next, 50 parts of isobutyl methacrylate, 31.5 parts of 2-ethylhexyl methacrylate, 8.5 parts of γ-methacryloxypropyltrimethoxysilane, 10.5 parts of acrylic acid and t-butylperoxy-2-ethylhexanoate.2.
A mixed solution consisting of 5 parts was added dropwise at 100 ° C. over 3 hours, then heated to 105 ° C. and maintained for 2 hours to terminate the reaction. The resulting silyl group-containing vinyl resin solution had a solid content concentration of 50% and an acid value of the resin of 65 mgKOH /
and the number average molecular weight was 10,000.

<Preparation of Organic-Inorganic Composite Resin Paint a> (Enamel Paint) In a reactor equipped with a reflux condenser and a stirrer,
Obtained by preparing 23 parts of a partial hydrolyzed condensate of methyltrimethoxysilane which is the component (a), 8 parts of methyltrimethoxysilane, 1.7 parts of dimethyldimethoxysilane, and the above-mentioned vinyl resin solution containing a silyl group (b). 25 parts of a silyl group-containing vinyl resin solution as a component) and 10 parts of isopropanol are added and mixed, and then 3.0 parts of ion-exchanged water and 0.05 part of 1N hydrochloric acid are added and reacted at 60 ° C. for 3 hours. It was Next, 0.3 part of monoacetylacetonate bis (ethylacetoacetate) aluminum and 0.8 part of ion-exchanged water were added, and the mixture was further reacted at 60 ° C. for 3 hours. Next, 0.55 parts of dimethylaminoethanol and 37 parts of water were added, and the mixture was stirred at 50 ° C. for 1 hour, and then depressurized (1.3 × 1).
After removing the solvent under 0 ⁴ Pa), solid content concentration of 35
Dilution adjustment was performed so as to be 100% to prepare an organic-inorganic composite resin aqueous dispersion.

Organic-inorganic composite resin aqueous dispersion 10 obtained above
A coloring agent (the same as that used in the preparation of the acrylic emulsion coating composition 1) was added to 0 part at a ratio of 15% of the solid content for coloring. Immediately before coating, 1 part of the amino group-containing alkoxysilane compound and 2.4 parts of the epoxy group-containing alkoxysilane compound were mixed with this to prepare an organic-inorganic composite resin coating material a.

<Preparation of Organic-Inorganic Composite Resin Paint b> (Color Clear Paint) Except that the amount of the colorant (the same as that used in the preparation of the acrylic emulsion paint 1) was 3% of the solid content. An organic-inorganic composite resin coating material b was prepared in the same manner as the above-mentioned organic-inorganic composite resin coating material a.

Reference Examples 1 to 4 The above acrylic emulsion paint 1, acrylic emulsion paint 3, organic-inorganic composite resin paint a, and organic-inorganic composite resin paint b were each applied to a glass plate with an applicator (6
mil), and dried at 120 ° C. for 3 minutes. Then, it was dried at 40 ° C. for 1 week to prepare a coated plate. Each coated plate was evaluated by the following methods. The results are shown in Table 1. Appearance: The appearance of the coating film formed on the coated plate was visually determined. Hardness: Pencil hardness measured according to JIS K5600.

Examples 1 to 4 and Comparative Examples 1 to 2 As an undercoat paint on the surface of an uncured cement roof tile, as shown in Table 2, the above acrylic emulsion paints 1, 2 or 3 were used.
Was applied by a flow coater and dried by a jet oven dryer. Then, the uncured cement roof tile was heated up to a temperature of 60 ° C. at a temperature rising rate of 20 ° C./hour as an initial curing, held in this state for 5 hours, and then cooled to room temperature for curing. As shown in Table 2, the above-mentioned organic-inorganic composite resin coating a as an overcoat for this cement roof tile,
The organic-inorganic composite resin coating material b or the above acrylic emulsion coating material 1 was applied with a flow coater and dried with a jet oven dryer to prepare a coated plate. Each coated plate was evaluated by the following methods. The results are shown in Table 2.

<Appearance> The appearance of the coating film formed on the coated plate was visually evaluated. <Curing resistance> Abnormalities in the appearance of the coating film after steam curing were visually evaluated according to the following criteria. ◯: Almost no efflorescence and no change in coating appearance. Δ: Slight efflorescence and slight change in appearance of coating film. X: The efflorescence and the appearance of the coating film are significantly changed.

<Warm water resistance> The coated plate was immersed in water at 60 ° C for 100
After immersion for a period of time, abnormalities in the appearance of the coating film were visually evaluated according to the following criteria. ◯: No change. Δ: Changes in gloss reduction, whitening, etc. are slight. X: Significant changes such as decrease in gloss and whitening.

<Weather resistance> Evaluation was carried out after 1,500 hours using a super UV accelerated weather resistance tester. ◯: There is no change in the appearance of the coating film, and the gloss retention rate is 80% or more. Δ: The change in the appearance of the coating film is slight, and the gloss retention rate is 50 to 8
Less than 0%. X: The coating film is significantly changed, and the gloss retention rate is less than 50%.

<Adhesion> Frost damage test 1 by ASTM-B method
A cellophane adhesive tape adhesion test was performed after 00, 300, and 600 cycles to evaluate the interlayer adhesion of the undercoat / topcoat. ◯: No peeling in 600 cycles. Δ: No peeling at 300 cycles, but peeling at 600 cycles. X: There is peeling after 100 cycles.

[0075]

[Table 1]

As is clear from Tables 1 and 2, the colored cement roof tile obtained by the method for producing a colored cement roof tile of the present invention using a specific undercoat paint and topcoat paint has excellent coating film performance. is doing. On the other hand, in Comparative Example 1 in which the acrylic emulsion coating 3 having an insufficient gel fraction was used as the undercoating coating, sufficient coating performance could not be obtained even when the organic-inorganic composite resin coating was applied to the topcoating. Further, even in Comparative Example 2 in which the acrylic emulsion paint 1 was used as both the undercoat paint and the topcoat paint, sufficient coating film performance could not be obtained.

[0077]

Industrial Applicability According to the method for producing a colored cement roof tile of the present invention, a colored cement roof tile having a coating film excellent in appearance, curing resistance, weather resistance, warm water resistance, coating film hardness and the like can be manufactured.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Yamada             2-1 Takamatsu, Kosai Town, Koga District, Shiga Prefecture             Kubota Shiga Factory (72) Inventor Junji Tsukao             3-8-2-402 Tatsunan, Ikuno-ku, Osaka-shi, Osaka Prefecture (72) Inventor Shoichi Horie             3-4-18 Nishiyama-cho, Nagata-ku, Kobe City, Hyogo Prefecture (72) Inventor Makoto Emi             4-9-5 Takejodai, Sakai City, Osaka Prefecture F-term (reference) 4G028 CA01 CB04 CC01

Claims (3)

[Claims] 1. After applying an undercoat paint containing an acrylic emulsion resin having a glass transition temperature of 20 to 100 ° C. and a gel fraction of 50% or more and a colorant on the surface of an uncured cement roof tile, and drying the coating film. , Steam curing the uncured cement roof tile, and then (A) (a) the general formula R ¹ _n Si (OR ² ) _4-n (wherein
R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is 1 to 1 carbon atoms.
5 is an alkyl group, and n is 1 or 2. 100 parts by mass of organosilane and / or a partial hydrolyzed condensate thereof and (b) a hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group, and having an acid value of 20 to 150 mgKOH. / G of silyl group-containing vinyl-based resin 5 to 200 parts by mass of the hydrolysis-condensation reaction product is neutralized with a neutralizing agent, water is added to obtain an organic-inorganic composite resin aqueous dispersion, (B) amino A hydrolytic condensation-reactive alkoxysilane having a group and (C) a top-coat paint containing a compound having an epoxy group in the molecule which has reactivity with the amino group of the component (B) is applied and baked and cured. A method for producing a colored cement roof tile, comprising: 2. The method for producing a colored cement roof tile according to claim 1, wherein the acrylic emulsion resin has a silyl group. 3. The method for producing a colored cement roof tile according to claim 1, wherein the topcoat paint is a color clear paint.