JP2006096639A - Decorative cement plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the durability of a decorative cement plate where a weather resistant coating layer exhibiting high weather resistance is formed on a decorative layer. <P>SOLUTION: The decorative layer 2 formed with a decorative cement material whose main material is cement is prepared on the surface side of a base plate 1 formed with a cement material for the base plate whose main material is cement. The weather resistant coating layer 3 is prepared on the decorative layer. The weather resistant coating layer 3 comprises a first coating layer 31 formed on the surface of the decorative layer 2 with an organic coating material whose main component is a resin and a second coating layer 32 formed with an organic and inorganic complex coating material containing an ultraviolet absorbing agent whose main component is cerium oxide and containing an organosilane as a main component. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a decorative layer formed of a decorative cement material mainly composed of cement on the surface side of a substrate formed from a cement material for a substrate mainly composed of cement, and the weather resistant coating layer on the decorative layer. The present invention relates to a decorative cement board.

  In recent years, building materials made of cement boards with substrates formed from cement materials for substrates mainly made of cement as roofing materials and wall materials have been used. There is a tendency for individuality to be achieved by making various improvements to functionality and functionality. In order to achieve such individualization, by providing a decorative layer made of a decorative cement material mainly composed of cement to which a pigment is added, the cement board has various design characteristics and functionality. Can do.

  As the decorative cement material, a colored cement material containing a pigment, a decorative cement material for forming an embossed appearance, a decorative cement material for producing a texture imparted with colored sand, and the like are used.

  In general, a decorative layer formed of such a decorative cement material is likely to have a problem of whiteness during curing. In order to solve such a problem, a sealer made of a polymer material is provided on the surface of the cured decorative layer. Application is generally performed. However, such a sealer tends to cause a peeling phenomenon due to ultraviolet ray deterioration accompanying long-term use.

Therefore, instead of the sealer, an organic-inorganic composite coating material in which an organic-inorganic composite resin obtained by hydrolytic condensation reaction of organosilane, a hydrolysis condensate thereof and a silyl group-containing vinyl resin is a binder. It is considered to provide a weather-resistant coating layer by applying a coating material. The coating layer formed of the coating material is less likely to crack, and therefore, a coating composition in which the organic-inorganic composite resin is a binding component has been attracting attention as a top coating material. However, since the covering material has low adhesion to the decorative layer, it is not actually provided directly on the decorative layer.
Therefore, in addition to the sealer, a weathering coating layer is provided by applying a coating material made of an organic-inorganic composite coating material. However, even in such a case, since it is necessary to make use of the appearance of the decorative layer, it is necessary to set the visible light-transmitting property of the weather-resistant coating layer to be high, but the coating for forming such a coating layer is necessary. The material has a high UV light transmissivity, and the paint cannot be effectively suppressed from being deteriorated by the UV light.

JP 2003-238272 A

  Therefore, it is conceivable to protect the sealer from ultraviolet rays by adding an ultraviolet absorber such as titanium oxide and zinc oxide to the weather resistant coating layer. However, in the case of zinc oxide or the like, the high temperature strength during curing of the substrate is considered. In the case of being unable to withstand alkaline conditions or being made of titanium oxide or the like, there has been a problem in that the coating layer is adversely affected due to its photocatalytic action, and those that are suitably used have not been known.

  Therefore, an object of the present invention is to form a weather-resistant coating layer that exhibits high weather resistance on a decorative cement board provided with a decorative layer, and to improve the durability of the decorative cement board.

  Accordingly, as a result of intensive studies on various ultraviolet absorbers, the present inventors have found that cerium oxide has an effect of adversely affecting the coating layer such as a photocatalytic action withstanding high-temperature strong alkali conditions during curing of the substrate. However, the inventors have experimentally found that it can be suitably contained in the organic-inorganic composite coating material, and have arrived at the present invention.

A feature of the present invention is that a decorative layer made of a decorative cement material mainly made of cement is provided on the surface side of a substrate formed of a cement material for a substrate mainly made of cement, and the decorative layer is weather-resistant. A decorative cement board provided with a covering layer,
The weather-resistant coating layer contains a first coating layer formed on the surface of the decorative layer from an organic coating material mainly composed of a resin, an ultraviolet absorber mainly composed of cerium oxide, and is mainly composed of organosilane. And a second coating layer formed from an organic-inorganic composite coating material as a component.

  In other words, the decorative cement board has a structure capable of exhibiting a design with excellent aesthetics because it has the decorative layer. According to the weather-resistant coating layer, since the weather resistance is high, long-term deterioration is suppressed due to high weather resistance. Can be improved.

Here, since the first coating layer is formed from an organic coating material containing a resin as a main component, the first coating layer contributes to prevention of whitening of the decorative layer, and is densely formed on the decorative layer. It plays the role of modifying the surface of the decorative layer so that the second coating layer is easily adhered.
Next, since the second coating layer contains an ultraviolet absorber, it is possible to suppress deterioration of the first coating layer due to ultraviolet rays, and from an organic-inorganic composite coating material containing organosilane as a main component. Since it is formed, it can be firmly adhered to the first coating layer and coated so that inconveniences such as peeling and blistering hardly occur.
Furthermore, since the ultraviolet absorber is cerium oxide, it is considered that the ultraviolet absorbing ability can be stably maintained over a long period of time because it can withstand high-temperature strong alkali conditions during curing and has a very weak photocatalytic action.

  Therefore, the weather-resistant coating layer formed by the first and second coating layers is a decorative cement board that does not deteriorate in performance due to curing, securely adheres to and protects the decorative layer, and does not easily deteriorate due to ultraviolet rays. Could be provided.

  In the present invention, the decorative cement material may be a colored cement material containing a pigment.

  That is, the aesthetics of the colored cement material are improved by the pigment, and furthermore, the aesthetics can be maintained over a long period of time by applying the above-mentioned weather resistant coating layer.

  Furthermore, the organic-inorganic composite coating material is preferably a composite resin containing a predetermined amount of cerium oxide having an average particle size of 0.4 to 0.5 μm so that the ultraviolet transmittance is 8.0% or less. .

  When the cerium oxide is added to the organic-inorganic composite coating material, if the formed weather-resistant coating layer is not highly transparent, the cosmetic layer may be covered and the texture of the cosmetic layer may be impaired. However, the composite resin containing a predetermined amount of cerium oxide having an average particle size of 0.4 to 0.5 μm so that the ultraviolet transmittance is 8.0% or less is high in transparency and the first coating layer is made of ultraviolet rays. Excellent ability to protect from.

  Moreover, it is preferable that the organic coating material is mainly composed of an acrylic resin.

  That is, the acrylic resin has high adhesion to the decorative layer, and is suitable for suppressing whiteness of the decorative layer.

[Embodiment of the Invention]
Hereinafter, the present invention will be described in detail.
The decorative cement board used in the present invention is made of, for example, a decorative cement material on a substrate 1 on which a cement material for a substrate mixed with cement, reinforcing fibers, aggregates and the like is spread in a plate shape while adding water. The decorative layer 2 is provided, and on the surface of the decorative layer, a weather-resistant coating layer 3 including a first coating layer 31 formed from an undercoat paint and a second coating layer 32 formed from a topcoat paint is provided.

<Undercoat paint>
The undercoat paint preferably contains an acrylic emulsion resin. This acrylic emulsion resin is, for example,
Acrylic acid,
An ethylenically unsaturated carboxylic acid selected from methacrylic acid and the like;
Alkyl esters of acrylic acid and methacrylic acid,
Vinyl aromatic compounds,
Acrylic nitrile,
Methacrylonitrile,
Saturated carboxylic acid vinyl ester,
Vinyl halide,
butadiene,
It can be obtained by emulsion polymerization of a monomer mixture composed of one or two or more olefins selected from ethylene or the like in the presence of an emulsifier.

The acrylic emulsion resin preferably has a silyl group. As such a silyl group-containing acrylic emulsion resin, for example,
γ-methacryloxypropylmethyldimethoxysilane,
γ-methacryloxypropylmethyltrimethoxysilane,
γ-methacryloxypropylmethyldiethoxysilane,
Silyl group-containing unsaturated monomers such as γ-methacryloxypropylmethyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane,
γ-glycidoxypropylmethyldiethoxysilane,
γ-glycidoxypropyltriethoxysilane,
N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane,
One or more selected from the group consisting of silane coupling agents containing a glycidyl group or amino group, such as N-β (aminoethyl) γ-aminopropylmethyltrimethoxysilane, are added to the mixture, and then an emulsifier. And those having a silyl group introduced by emulsion polymerization in the presence of.

The acrylic emulsion resin and the silyl group-containing acrylic emulsion resin have a glass transition temperature (hereinafter referred to as Tg) of 20 to 100 ° C., preferably 40 to 80 ° C., and a gel fraction of 50% or more, preferably 75. Use up to 80% or more. Such an emulsion resin is excellent in curing resistance, and in particular, a silyl group-containing acrylic emulsion resin exhibits extremely high performance. When the Tg of these emulsion resins is less than 20 ° C., the dried coating film is melted and dissolved due to heat during curing, and defects such as blocking are likely to occur. Conversely, the Tg of the emulsion polymer is 100 If it exceeds ° C., film formation during drying tends to occur, which is not preferable.
Further, when the gel fraction of the emulsion resin is less than 50%, it is preferable because the dried coating film is melted and eluted by heat or the like during curing, and efflorescence due to alkali from the base tends to occur. Absent.
Furthermore, the silyl group-containing acrylic emulsion resin is preferable because the adhesion to the top coating is improved by the introduction of the silyl group.

The undercoat paint used in the present invention contains a colorant. As this colorant, a typical inorganic pigment can be cited as a representative, but depending on the color, an organic pigment having alkali resistance and weather resistance may be used.
For example,
When coloring black, carbon black, iron oxide, etc.
When coloring in red, petals, etc.
When colored green, chromium oxide, etc.
When coloring blue, phthalocyanine blue, etc.
In the case of coloring white, titanium dioxide or the like can be used.
The color pigment is not limited to these, and a color pigment blended in a normal paint can be used.

  The color pigment is preferably blended in the undercoat paint at a ratio of 0.1 to 15% by mass, and can be sufficiently colored by blending within this range. The undercoat used in the present invention includes the above-mentioned acrylic emulsion resin or silyl group-containing acrylic emulsion resin, the above colorant, an organic solvent, a filler, a dye, and further a curing accelerator, a thickener, and a pigment dispersant. Various additives such as can be contained.

<Topcoat paint>
The top coat contains the following (A) to (C).
(A) An organic-inorganic composite resin aqueous dispersion obtained by neutralizing the hydrolysis-condensation reaction product of (a) and (b) with a neutralizing agent and adding water.
(A) 100 parts by mass of an organosilane represented by Chemical Formula 1 and a partially hydrolyzed condensate thereof.
(B) 5 to 200 parts by mass of a silyl group-containing vinyl resin having 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.
(B) Alkoxysilane having an amino group and capable of hydrolysis condensation reaction.
(C) The compound which has the epoxy group which has the reactivity with the amino group of the said (B) component in a molecule | numerator.

[Chemical formula 1]
(R1) nSi (OR2) 4-n
R1: an organic group having 1 to 8 carbon atoms,
R2: an alkyl group having 1 to 5 carbon atoms,
n: 1 or 2

Examples of R1 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, an i-propyl group, an n-butyl group, an i-butyl group, Examples thereof include s-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group, and octyl group. Preferred alkyl groups are those having 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, chlorine atom, bromine atom, fluorine atom), (meth) acryloyl group, mercapto group, and alicyclic group.

  The alkyl group represented by R2 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, an n-butyl group, and an i-butyl group. , S-butyl group, t-butyl group, pentyl group and the like. Preferred alkyl groups are those having 1 to 2 carbon atoms.

Specific examples of the organosilane represented by Chemical Formula 1 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-trifluoropropyltriethoxysilane,
Cyclohexyltrimethoxysilane,
γ-methacryloxypropyltrimethoxysilane,
γ-methacryloxypropyltriethoxysilane,
γ-mercaptopropyltrimethoxysilane,
γ-mercaptopropyltriethoxysilane,
Phenyltrimethoxysilane,
Phenyltriethoxysilane,
Dimethyldimethoxysilane,
Dimethyldiethoxysilane,
Diethyldimethoxysilane,
Diethyldiethoxysilane,
Diphenyldimethoxysilane,
Diphenyldiethoxysilane,
Methylphenyldimethoxysilane,
Examples thereof include dimethyldipropoxysilane. Preferably,
Methyltrimethoxysilane,
Methyltriethoxysilane,
Dimethyldimethoxysilane.
These organosilanes can be used alone or in combination of two or more.

  The component (a) may be a partially 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. By using such a molecular weight condensate, a coating film with good adhesion can be obtained without deteriorating storage stability. Moreover, it is appropriate that the partial hydrolysis-condensation product of organosilane has one or more, preferably 3 to 30, —OH groups or —OR 2 groups bonded to silicon atoms.

Specific examples of such a condensate include commercially available KR-211, KR-212, KR-213, KR-214, KR-216, KR-218 manufactured by Shin-Etsu Chemical Co., Ltd., and TSR manufactured by Toshiba Silicone. -145, TSR-160, TSR-165, YR-3187, and the like.

  For the component (a), the mass ratio of the organosilane having an n value of 1 and a partially hydrolyzed condensate thereof to the organosilane having an n value of 2 and the partially hydrolyzed condensate thereof is 50:50 to 100: 0. It is preferable to use a mixture of 60:40 to 95: 5, since it reacts stably during the hydrolytic condensation reaction and a coating film with good crack resistance is obtained.

  The component (b) used in the present invention has at least one hydrolyzable silyl group or a silyl group having a silicon atom bonded to a hydroxyl group at the terminal or side chain of the vinyl resin in one molecule of the resin, preferably It is a vinyl resin having 2 or more and an acid value of 20 to 150 mgKOH / g and a molecular weight of, for example, about 1000 to 50000.

  The above silyl group is represented by Chemical Formula 2.

[Chemical formula 2]
-SiXm (R3) (3-m)
X: alkoxy group, acyloxy group, halogen group, ketoximate group,
Mercapto group, alkenyloxy group,
Hydrolyzable groups such as phenoxy groups or hydroxyl groups,
R3: hydrogen or an alkyl group having 1 to 10 carbon atoms, an aryl group,
Monovalent hydrocarbon groups such as aralkyl groups,
m: an integer from 1 to 3

  The silyl group-containing vinyl resin is produced, for example, by reacting a hydrosilane compound represented by Chemical Formula 3 with a vinyl resin having a carbon-carbon double bond according to a conventional method.

[Chemical formula 3]
H-SiXm (R3) (3-m)
X, R3, m are the same as those in Chemical formula 2

As the hydrosilane compound, for example,
Methyldichlorohydrosilane,
Methyldiethoxyhydrosilane,
A typical example is methyldiacetoxyhydrosilane.
The amount of the hydrosilane compound used in the production of the silyl group-containing vinyl resin is suitably a molar amount that is 0.5 to 2 times the number of carbon-carbon double bonds contained in the vinyl resin. .

The vinyl resin is
(Meth) acrylic acid, itaconic acid, fumaric acid and other carboxylic acids or maleic anhydride and other acid anhydrides as essential monomer units,
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, A copolymer containing a vinyl monomer selected from the group consisting of α-methylstyrene, vinyl acetate, vinyl propionate and the like as a comonomer unit is preferably used.
By radical copolymerization of allyl (meth) acrylate, diallyl phthalate and the like during the production of the copolymer, it becomes possible to introduce a carbon-carbon double bond for hydrosilylation reaction into the vinyl resin.

  In addition, it is necessary to contain said carboxylic acid or acid anhydride in the constituent monomer of the copolymer so that the acid value of the obtained vinyl-based resin is 20 to 150 mgKOH / g, preferably 50 to 120 mgKOH / g. is there. If the acid value of the vinyl resin is less than 20 mgKOH / g, the storage stability of the resulting aqueous dispersion will deteriorate. Conversely, if the acid value of the vinyl resin exceeds 150 mgKOH / g, the water resistance of the resulting coating film will be reduced. Since hot water resistance deteriorates, neither is preferable.

In addition, as another method for producing the silyl group-containing vinyl resin,
A vinyl monomer containing the carboxylic acid or acid anhydride;
2-hydroxyethyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate,
A hydroxyl group-containing monomer selected from 2-hydroxy vinyl ether and the like;
γ- (meth) acryloxypropyltrimethoxysilane,
γ- (meth) acryloxypropyltriethoxysilane,
β- (meth) acryloxyethyltrimethoxysilane,
β- (meth) acryloxyethyltriethoxysilane,
γ- (meth) acryloxypropylmethyldimethoxysilane,
γ- (meth) acryloxypropylmethyldiethoxysilane,
γ- (meth) acryloxypropylmethyldipropoxysilane,
γ- (meth) acryloxybutylphenyldimethoxysilane,
γ- (meth) acryloxypropyldimethylmethoxysilane,
There is also a method of radical polymerization with a silyl group-containing vinyl compound selected from γ- (meth) acryloxypropyldiethylmethoxysilane and the like.
Specific examples of these silyl group-containing vinyl resins include, for example, Kanekaze Murak manufactured by Kaneka Chemical Co., Ltd., which is a commercial product.

  Next, the manufacturing method of the organic-inorganic composite resin aqueous dispersion of 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 component (a) and the component (b) to cause hydrolysis and condensation reactions. The mixing ratio of the component (a) and the component (b) is suitably 5 to 200 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the component (a).

  When the amount of the component (b) is less than 5 parts by mass, the appearance, crack resistance, frost damage resistance, alkali resistance, etc. of the resulting coating film are deteriorated. Conversely, the amount of the component (b) is 200 parts by mass. When it exceeds, the weather resistance of a coating film obtained, stain resistance, etc. will worsen, and is unpreferable.

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

  Examples of the catalyst added to the mixture of the component (a) and the component (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 suitably such that the pH of the above mixture is 3-6. Regarding the hydrolysis reaction, the mixture of the component (a) and the component (b) is reacted in the presence of water and a catalyst at 40 to 80 ° C., preferably 45 to 65 ° C. for 2 to 10 hours with stirring. However, the method is not limited to this method.

In addition, although it is possible to implement the hydrolysis-condensation reaction of (a) component and (b) component in one step as described above, from the viewpoint of storage stability of the product, the following two steps It is preferable to make it react with.
That is, as a first step, in the presence of water and a catalyst, 40 to 80%, preferably 45 to 70% of the hydrolyzable groups initially present in the mixture of the component (a) and the component (b). The reaction is carried out at 40 to 80 ° C., preferably 45 to 65 ° C. for 1 to 8 hours with stirring so that% can undergo a hydrolytic condensation reaction.
As the second stage, following the first stage, further trialkoxyboranes such as trimethoxyborane and triethoxyborane,
Zirconium chelate compounds such as tri-n-butoxyethyl acetate zirconium, di-n-butoxy (ethyl acetate) zirconium, tetotarakis (ethyl acetate) zirconium,
Titanium chelate compounds such as diisopropoxybis (acetylacetate) titanium, diisopropoxybis (ethyl acetate) titanium,
Add organic metal compound catalyst such as aluminum chelates such as monoacetyl acetate bis (ethyl acetoacetate) aluminum and diisopropoxyethyl acetoacetate aluminum with water,
Causes hydrolysis and condensation reactions.
The trialkoxyborane and the organometallic compound catalyst used in the second stage promote the condensation reaction, so that the appearance, weather resistance, stain resistance, hot water resistance and the like of the coating film can be improved.

  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 component (a) and component (b). And an amount sufficient for the condensation reaction. The amount of the catalyst added in the second stage is 0.001 with respect to 100 parts by mass of the total amount of the reaction product obtained in the first stage and the unreacted (a) component and (b) component. ˜5 parts by mass, preferably 0.005 to 2 parts by mass is suitable. The hydrolysis condensation reaction in the second stage is suitably performed at 40 to 80 ° C. for 2 to 5 hours as in the first stage.

  In addition, the hydrolysis-condensation reaction product is in a solution state with an alcohol component generated by the reaction, or with the alcohol component and an organic solvent described later added as necessary. A neutralizing agent is added to the solution of the organic-inorganic composite resin, which is the reaction product thus obtained, and uniformly dispersed. After neutralization, water is added, or the neutralizing agent and water are added simultaneously, The mixture is forcibly dispersed by stirring to obtain an aqueous dispersion (emulsion).

The amount of the neutralizing agent is an amount that neutralizes 50 to 100%, preferably 70 to 100%, of the acid groups in the organic-inorganic composite resin as the reactant so that a stable emulsion is obtained. .
As a neutralizing agent,
Triethylamine,
Triethanolamine,
Dimethylethanolamine,
Monoethanolamine,
N-methyldiethanolamine,
N, N-dimethylethanolamine,
A typical example is morpholine.

  Further, the amount of water added after neutralization is arbitrarily determined in consideration of the coating workability of the paint, but usually an amount such that the solid content of the paint composition is 10 to 70% by mass is appropriate. . In addition, the alcohol produced | generated by said hydrolysis condensation reaction remains in the organic inorganic composite resin aqueous dispersion obtained in this way. Accordingly, if the aqueous dispersion is used as it is as a coating composition, the volatile organic component (VOC) increases, and therefore, it is preferable to remove the alcohol component under reduced pressure according to a conventional method.

  The component (B) is an alkoxysilane having an amino group in the molecule and capable of undergoing a hydrolytic condensation reaction. Specifically, an amino group-containing alkoxysilane represented by Chemical Formula 4 can be preferably used.

[Chemical formula 4]
(R6-NH-R5-) nSi (OR4) 4-n
R4: C1-C5 alkyl group
R5: an alkylene group having 1 to 5 carbon atoms
R6: 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,
Substituted or unsubstituted amino group
n: 1 or 2

The alkyl group as R4 may be linear or branched, and examples thereof include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, and s-butyl. Group, t-butyl group and pentyl group. Preferred alkyl groups are those having 1 to 2 carbon atoms.
The alkylene group as R5 may be linear or branched, and examples thereof include a methylene group, an ethylene group, and a propylene group.
The alkyl group as R6 is the same as in the case of R4.
Examples of the cycloalkyl group as R6 include a cyclohexyl group and a cycloheptyl group.
Moreover, as an aryl group as R6, a phenyl group can be mentioned, for example. Furthermore, examples of the amino group as R6 include those in which one or both of the hydrogen atoms in the amino group are substituted with an alkyl group having 1 to 5 carbon atoms.

As the amino group-containing alkoxysilane represented by the chemical formula 4, for example,
γ-aminopropyltrimethoxysilane,
γ-aminopropyltriethoxysilane,
N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane,
N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane,
N- (β-aminoethyl) -γ-aminopropylmethyldiethoxysilane,
N-cyclohexyloxy γ-aminopropyltrimethoxysilane,
N-cyclohexyl-γ-aminopropyltriethoxysilane,
γ- (2-aminoethyl) -aminopropyltrimethoxysilane,
γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane,
γ-anilinopropyltrimethoxysilane can be mentioned.

The compounding amount of the alkoxysilane as the component (B) is preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the organic inorganic composite resin aqueous dispersion as the component (A) (organic inorganic composite resin). More preferably, 2 to 15 parts by mass is appropriate. In addition, when there are few compounding quantities of (B) component, there exists a tendency for the sclerosis | hardenability and stain resistance of the coating film obtained to worsen, and conversely when too large, hot water resistance and crack resistance will worsen. Tend.

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

In particular,
γ-glycidoxypropyl trimexylsilane,
γ-glycidoxypropyltriethoxysilane,
γ-glycidoxypropylmethyldimethoxysilane,
γ-glycidoxypropylmethyldiethoxysilane,
γ-glycidoxypropyl triisopropenyloxysilane,
γ-glycidoxypropyltriiminooxysilane,
β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane,
an adduct of γ-isocyanatopropyltriisopropenyloxysilane and glycidol,
Butyl glycidyl ether,
Polyoxyethylene glycidyl ether,
Cardura E (product name by Shell),
Butyl phenyl glycidyl ether,
Epicoats 815, 828, 834 (trade names manufactured by Yuka Shell Epoxy Co., Ltd.) and the like and their emulsions are representative examples.
Among the epoxy group-containing compounds, the use of an epoxy group-containing alkoxysilane compound having a hydrolyzable silyl group is preferred because the curability of the coating film is improved and the heat resistance, alkali resistance and the like are improved.

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

  In addition, when the amount of the epoxy group-containing compound of the component (C) is less than the above range, the hot water resistance of the obtained coating film tends to be deteriorated. There is a tendency for the property, crack resistance, etc. to deteriorate. The (B) component amino group-containing alkoxysilane compound and the (C) component epoxy group-containing compound are mixed with the aqueous dispersion of the component (A) and dispersed before use.

  The component (B) and the component (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 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) to provide hot water resistance, alkali resistance, weather resistance, Forms a cured coating film with excellent contamination and solvent resistance.

  The top coat is composed of the organic-inorganic composite resin aqueous dispersion of component (A) as the main component and the amino group-containing alkoxysilane compound (B) as the curing agent and component (C) described above. A main component of a certain epoxy group-containing compound, and, if necessary, water, an organic solvent and a filler, a dye, and a curing accelerator for improving the storage stability and coating workability of the coating composition. , Thickeners, pigment dispersants and other additives.

  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 ketones such as acetone and methyl ethyl ketone, and toluene. Organic solvents with various hydrophobic organic solvents for paints such as xylene, ethyl acetate and butyl acetate can be used.

  The organic solvent can be blended as a solvent so that the reaction occurs homogeneously during the production of the organic inorganic composite resin aqueous dispersion as the component (A). The blending amount of the organic solvent is preferably 0 to 20% by mass, more preferably 0 to 10% by mass of the coating composition.

  As the filler, a normal inorganic / organic dye / pigment can be used. Specifically, titanium oxide, zinc sulfide, zinc white, lead white, lithopone, carbon black, oil smoke, bitumen, phthalocyanine blue, ultramarine, carmine FB, yellow lead, zinc yellow, Hansa yellow, ocher, bengara, inactive content Representative examples include azo dyes. The blending amount 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.

  Further, cerium oxide as an inorganic ultraviolet absorber is added to the top coating.

  The top coat used in the present invention is preferably a clear paint in order to make use of the texture of the decorative layer. In the case of a color clear paint, the above-mentioned inorganic / organic dye / pigment may be contained at a ratio of about 0.01 to 15% by mass relative to the resin solid content. If the amount of the inorganic / organic dye / pigment is less than 0.01% by mass, a sufficient change in color tone cannot be obtained. Conversely, if the amount exceeds 15% by mass, the transparency of the formed coating film decreases, resulting in a deeper depth. There is a tendency that a certain color change cannot be obtained. In particular, an inorganic / organic dye / pigment amount of about 0.05 to 10% by mass is preferred.

  The average particle diameter of cerium oxide is set to 0.4 to 0.5 μm, so that it is easy to ensure transparency with respect to the top coat. Further, if the amount of cerium oxide added to the top coat is set to a predetermined amount such that the UV transmittance is 8.0% or less, the UV transmittance of the top coat can be effectively reduced, and the UV of the undercoat can be reduced. The texture of the decorative layer can be utilized while preventing deterioration due to.

<Board>
The substrate cement material is composed of aggregate, cement, and reinforcing fibers, and is prepared by dry uniform mixing with a mixer while automatically weighing each raw material supplied from a hopper. Silica sand having a brane value of 3000 to 5000 is used as the aggregate, and 50% is added to the cement. Portland cement is used as the cement. As the reinforcing fibers, pulp fibers having an average fiber length of 2 mm are suitably used, and 7 to 15% is added to the cement. The substrate is formed into a plate having a thickness of about 5 mm by dry-molding the substrate cement material.

<Makeup layer>
The decorative cement material is composed of aggregate, cement, and pigment, and is prepared in the same manner as the substrate cement material. As the aggregate, silica sand having an average particle diameter of 0.1 mm is used, and 10% by weight is added to the cement. As the cement, Portland cement is preferably used. As the pigment, for example, a black pigment is oxidized. Iron is used and added to the cement at 10% The colored layer is molded to a thickness of about 0.5 mm using the colored cement material.
The coated cement material has a composition obtained by removing the pigment from the colored cement material, and the coated layer is molded to a thickness of about 0.5 mm using the coated cement material.

  In addition to forming a colored layer from a colored cement material, the decorative layer may be one that is decorated with a texture in which sand particles are dispersed on the surface, or a decorative process that forms an emboss. Collectively referred to as a decorative layer.

  The cement used for the substrate cement material and the decorative cement material is not limited to por and land cement, and various known materials such as alumina cement can be used.

<Coating method>
The undercoat paint is applied to the surface of the decorative layer according to a normal coating method such as brush, spray, roll coater, flow coater, shower coater, dipping, etc., and the coating film is dried according to a normal drying method, followed by steam curing. As an example of this steam curing, as an initial curing, the temperature is raised to 60 ° C. at a temperature rising rate of 20 ° C./hour, held in this state for 5 hours, and then cooled to room temperature.

  After that, the above-mentioned top coat is applied to the colored cement tile surface according to a normal coating method such as brush, spray, roll coater, flow coater, shower coater, dipping, and baked at a temperature of 300 ° C. or less, for example, according to a normal baking method. To form a cured coating.

〔Example〕
The present invention will be specifically described below with reference examples, examples, and comparative examples. In the reference examples, examples, and comparative examples, “parts” and “%” are “parts by mass” and “mass%”, respectively.

<Board and decorative layer>
As shown in FIG. 2, the substrate cement material 11 is mixed and prepared, and the substrate cement material 11 is continuously dropped and supplied onto the transport surface of the endless conveyor 13 being rotated by a drop supply device 12.
The coated cement material 11 dropped and supplied to the endless conveyor 13 is made to have a substantially constant thickness by the baffle plate 14 and then pressed by the pressure roller 15. After the water for cement hardening is sprayed by the watering device 16, it is further pressed by the pressure roller 17 to mold the substrate 1 having a substantially constant thickness.
Further, the decorative cement material 21 is spread on the upper surface of the substrate 1, and the decorative layer 2 is provided on the substrate 1 by the same steps as those of the substrate (22 to 27 in the figure correspond to 12 to 17 in the figure). The obtained plate material is cut into a rectangular plate A having an appropriate size after being conveyed.

  The rectangular plate A that has been naturally cured for several days is punched into a plate B having a predetermined size and shape by a punch press. The punched plate B is dried after the first coating layer 31 is formed by the undercoat coating apparatus, and is dried after the second coating layer 32 is formed by the top coating apparatus.

<Preparation of undercoat paint>
While stirring 80 parts of an acrylic emulsion resin having a glass transition temperature of 75 ° C. and a gel fraction of 80%, 2 parts of a film forming aid (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate) are added therein. , 12.4 parts of water, 0.5 parts of a neutralizing agent (50% aqueous solution of dimethylaminoethanol), and a thickener (Primal ASE, an alkali swelling type thickener available from Rohm and Haas Japan KK) -60) 5 parts of an aqueous solution and 0.1 part of an antifoaming agent (Formaster VL, which is a silica silicone-based antifoaming agent available from San Nopco Co., Ltd.) are added and stirred for 30 minutes. The acrylic emulsion paint was added in a proportion and colored.

  In addition, said coloring agent can be obtained from 17.7 parts of ion-exchange water, 0.2 part of thickener (Natrazole 250HR available from Hercules Japan Co., Ltd.), and dispersant (Rohm and Haas Japan Co., Ltd.). 5 parts of OROTAN731DP), 0.5 part of a wetting and dispersing agent (Neonyogen 140A available from Daiichi Kogyo Seiyaku Co., Ltd.), 9 parts of carbon black (Asahi # 50 available from Asahi Carbon Co., Ltd.), titanium dioxide (Ishihara Sangyo Co., Ltd.) 10 parts of Typek CR-97), 57.5 parts of barium sulfate (precipitated barium sulfate # 100 available from Sakai Chemical Industry Co., Ltd.), and 1 part of antifoam (Nopco 8034 available from San Nopco Corporation) And add 30 parts of glass beads to it until the particle gauge becomes 20 μm or less. One in which a disperser obtained by stirring.

<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. with stirring. Next, from 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 2.5 parts of t-butylperoxy 2-ethylhexanoate The resulting mixed solution was added dropwise at 100 ° C. over 3 hours, then heated to 105 ° C. and maintained for 2 hours to complete the reaction. The resulting silyl group-containing vinyl resin solution had a solid concentration of 50%, an acid value of the resin of 65 mgKOH / g, and a number average molecular weight of 10,000.

<Preparation of top coat>
In a reactor equipped with a reflux condenser and a stirrer, 23 parts of a partially hydrolyzed condensate of methyltrimethoxysilane as component (a), 8 parts of methyltrimethoxysilane, 1.7 parts of dimethyldimethoxysilane, containing the silyl group After adding and mixing 25 parts of the silyl group-containing vinyl resin solution (b) component obtained in the preparation of the vinyl resin solution and 10 parts of isopropanol, 3.0 parts of ion-exchanged water and 0.05% of 1N hydrochloric acid 0.05 Part was added and reacted at 60 ° C. for 3 hours. Next, 0.3 part of monoacetylacetonate bis (ethylacetoacetate) aluminum and 0.8 part of ion-exchanged water were added and 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. After removing the solvent under reduced pressure (1.3 × 10 4 Pa), the solid content concentration was 35% with water. Dilution adjustment was performed to prepare an organic-inorganic composite resin aqueous dispersion.

  To 100 parts of the organic-inorganic composite resin aqueous dispersion obtained above, a colorant (same as that used in the preparation of the acrylic emulsion paint described above) was added in various amounts with respect to the solid content, and was colored. Immediately before coating, 1 part of an amino group-containing alkoxysilane compound and 2.4 parts of an epoxy group-containing alkoxysilane compound were mixed with this to prepare 6 types of topcoat paints a1-6. Furthermore, top coating materials A1 and A2 in which cerium oxide as an ultraviolet absorber was further added for a1 and a2 therein were prepared.

<Formation of weather-resistant coating layer>
An undercoat paint was applied to the surface of the decorative layer with a flow coater and dried with a jet oven dryer. Then, the obtained board | plate material was heated up to the temperature of 60 degreeC by the temperature increase rate of the temperature of 20 degree-C / hour as an initial stage curing, and it hold | maintained in this state for 5 hours, and cooled to room temperature after that, and was cured. A top coat was applied to the plate material with a flow coater and dried with a jet oven dryer to obtain a decorative cement plate. The properties of each decorative cement board were evaluated by the following methods. The results are shown in Tables 1 and 2.

<Ultraviolet transmittance>
The ultraviolet light transmittance of the weather-resistant coating layer was calculated by injecting light of the measurement wavelength into the measurement sample and measuring the transmitted light by spectroscopy (spectrophotometer: U-3410, manufactured by Hitachi, Ltd.).

<Gloss retention of coating film (weather resistance)>
The gloss retention was measured with a gloss meter after 1500 hours with a Super UV accelerated weathering tester.

From Table 1, when the addition rate of the colorant is 0.8% or more, the ultraviolet transmittance is greatly suppressed, and a considerably high weather resistance (gloss retention of the coating film) can be obtained. May be damaged. Therefore, as shown in Table 2 (the samples No. 11 to 13 are obtained by further adding cerium oxide to the samples No. 1 to 3, respectively), the amount of cerium oxide to be added to the top coat is transmitted through ultraviolet rays. When the ratio is added to 8.0% or less, extremely high weather resistance can be obtained and a highly transparent second coating layer can be formed, which is particularly useful as a weather resistant coating layer for decorative cement boards. It was found that it was used.
There are several other UV absorbers that can be used, but cerium oxide is most suitable in the present invention.
For example, titanium oxide is semi-permanent with respect to the ultraviolet absorption effect like cerium oxide, but has the disadvantage that it has a feeling of opacity and further has a photoactivity so that the surrounding resin can be deteriorated.
Table 3 below summarizes the characteristics of various ultraviolet absorbers.

  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 produced.

Schematic diagram of decorative cement board Manufacturing process diagram of decorative cement board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Cosmetic layer 3 Weatherproof coating layer 31 First coating layer 32 Second coating layer

Claims (4)

A decorative layer formed from a decorative cement material mainly composed of cement is provided on the surface side of the substrate formed from a cement material for a substrate mainly composed of cement, and a weather resistant coating layer is provided on the decorative layer. A decorative cement board,
The weather-resistant coating layer contains a first coating layer formed on the surface of the decorative layer from an organic coating material mainly composed of a resin, an ultraviolet absorber mainly composed of cerium oxide, and is mainly composed of organosilane. A decorative cement board comprising a second coating layer formed from an organic-inorganic composite coating material as a component.   The decorative cement board according to claim 1, wherein the decorative cement material is a colored cement material containing a pigment.   The organic-inorganic composite coating material is a composite resin containing a predetermined amount of cerium oxide having an average particle size of 0.4 to 0.5 µm so that the ultraviolet transmittance is 8.0% or less. Cosmetic cement board as described in. The decorative cement board according to any one of claims 1 to 3, wherein the organic coating material contains an acrylic resin as a main component.

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