JP2021055411A - Roofing material - Google Patents

Abstract

To provide cement roofing material of the present invention, excellent in waterproof not to be deformed.SOLUTION: A purpose of the present invention is achieved by roofing material comprising cement substrate roofing material of which a front side has a front side coat and a rear side has a rear side coat, respectively, wherein the rear side coat contains an inorganic layer compound. Preferably, for the rear side coat, 5 to 35 mass% of the inorganic layer compound is contained, and a permeable water volume of the front side coat is 2.0 mL/day or less and a permeable water volume of the rear side coat is 2.0 mL/day or less as well as a permeable water volume of the rear side coat is equal or less than the permeable water volume of the front side coat.SELECTED DRAWING: Figure 1

Description

The present invention relates to a roofing material, and more particularly to a cement-based roofing material having a waterproof coating film on the back surface.

In the roofing material market for detached houses, in recent years, many roofing materials using fiber-reinforced cement, which has been reduced in weight and has excellent earthquake resistance, have been used (Patent Document 1).
Rainwater flows down along the slope of the roof, but because the roofing material is nailed, part of it may enter the gap on the back side of the roofing material. The rainwater that has entered collects between the field board covered with the tarpaulin and the roofing material, and the back surface of the roofing material is exposed to rainwater for a long period of time, which may lead to deterioration and distortion of cement. Therefore, a technique of providing a waterproof layer on the back surface of the roofing material has also been proposed (Patent Document 2).

JP-A-2007-9655 Japanese Patent No. 37346555

In recent years, roof slopes have tended to be designed gently. However, when the slope of the roof is gentle, the rain from the side hit easily enters the gap on the back side of the roofing material, and the rainwater once accumulated on the back side is hard to be discharged. Therefore, rainwater accumulates in the gap between the field board or the tarpaulin and the roofing material, so that the back side becomes wet for a long period of time, and the time for which the humidity difference between the roof surface and the back side occurs becomes long. Therefore, a deformation phenomenon that the roofing material warps may occur.

An object of the present invention is to provide a cement-based roofing material having excellent water resistance and not deforming.

The present invention has been achieved by:

(1) A roofing material made of a cement-based base material, which has a front surface side coating film on the front surface side and a back surface side coating film on the back surface side, and at least the back surface side coating film is inorganic. A roofing material containing a layered compound.
(2) The roofing material according to 1 above, wherein the back surface side coating film contains 5 to 35% by mass of an inorganic layered compound.
(3) The water permeability of the front surface side coating film is 2.0 mL / day or less, the water permeability of the back surface side coating film is 2.0 mL / day or less, and the water permeability of the back surface side coating film is the front surface. The roofing material according to 1 or 2 above, which is equal to or less than the water permeability of the side coating film.
(4) The roofing material according to any one of 1 to 3 above, wherein the film thickness of the front surface side coating film is 15 to 70 μm, and the film thickness of the back surface side coating film is 10 to 120 μm.

According to the present invention, it is possible to provide a cement-based roofing material having excellent water resistance and not causing warpage for a long period of time.

It is a figure which shows the concept of the roofing material of this invention. It is a figure which shows the test instrument of the water permeability test. It is a figure which shows the position of the base point of the warp test piece of a base material. It is a figure which shows the warp test by water absorption of a base material.

Hereinafter, embodiments of the present invention will be described in detail.
<Roofing material>
The roofing material of the present invention is a roofing material made of a cement-based base material, and has a front surface side coating film on the front surface side and a back surface side coating film on the back surface side, and at least the back surface side coating. The membrane is characterized by containing an inorganic layered compound.

≪Back side coating film≫
The back surface coating film of the present invention contains at least a binder resin and an inorganic layered compound.

[Binder resin]
Examples of the binder resin of the present invention include acrylic resin, silicone resin, acrylic silicone resin, fluororesin, epoxy resin, vinyl resin, phenol resin, urethane resin, melamine resin, ketone resin and the like. Among these, acrylic resin or acrylic silicone resin is preferable from the viewpoint of improving the adhesiveness to the base material.

In particular, acrylic silicone resin is preferable because it can exhibit adhesiveness due to the affinity between the inorganic component and the cement component of the silicone resin in addition to the adhesiveness of the acrylic resin to the base material. These resins may be used alone or in combination of two or more. Further, these resins may be crosslinked in the coating film via a crosslinking agent or a curing agent.

As the acrylic resin, for example, one or more kinds of acrylic components selected from acrylic acid, methacrylic acid and its esters, amides, nitriles and the like, and copolymerizable ethylenically unsaturated monomers such as styrene and vinyltoluene. Examples thereof include a polymer obtained by polymerizing.

Specific examples of the acrylic component include compounds shown in the following (a) to (h). However, when the compound shown in the following (h) is used as the acrylic component, a siloxane condensation reaction also occurs in competition with the polymerization reaction. Therefore, in the present invention, the acrylic resin containing the compound shown in the following (h) as a constituent unit. Is classified as an acrylic silicone resin.

In such an acrylic silicone resin, the content of the compound shown in the following (h) is preferably 0.2% by mass or more and 15.0% by mass or less, and 0.5% by mass, based on the total amount of the monomers used. % Or more and 12.0% by mass or less are more preferable, and 0.5% by mass to 3% by mass is further preferable.

The acrylic resin also includes a polymer obtained by polymerizing an acrylic component with another monomer such as styrene or a vinyl group-containing ester compound (excluding the acrylic component).

(A): Ester of (meth) acrylic acid and alcohol having 1 to 24 carbon atoms For example, methyl methacrylate, 2-isocyanatoethyl methacrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth). Acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) Examples thereof include acrylate, isobornyl (meth) acrylate, tridecyl (meth) acrylate, and stearyl (meth) acrylate.

(B): Monoesteride of polyhydric alcohol and (meth) acrylic acid For example, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meth) acrylate, 4-hydroxy Examples thereof include butyl (meth) acrylate and polyethylene glycol mono (meth) acrylate.

(C): Carboxyl group-containing polymerizable unsaturated monomer For example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride and the like can be mentioned.
(D): Epoxy group-containing polymerizable unsaturated monomer Examples thereof include glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate.

(E): Aminoalkyl (meth) acrylate
For example, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like can be mentioned.

(F): (Meta) acrylamide or a derivative thereof For example, (meth) acrylamide, diacetone acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N-dimethylaminopropyl. Examples thereof include (meth) acrylamide, N-methylol acrylamide, N-methylol acrylamide methyl ether, and N-methylol acrylamide butyl ether.

(G): (Meta) acrylonitrile or a derivative thereof Examples thereof include (meth) acrylonitrile and 3-amino (meth) acrylonitrile.
(H): Alkoxysilyl group-containing (meth) acrylic acid ester or a derivative thereof For example, γ- (meth) acryloxypropyldimethoxysilane, γ- (meth) acryloxipropyltrimethoxysilane, γ- (meth) acryloxipropyl. Examples thereof include methyldiethoxysilane and γ- (meth) acryloxypropyltriethoxysilane.

The acrylic silicone resin is usually a resin having a block made of repeating units such as forming an acrylic resin and a block made of repeating units such as forming a silicone resin. For example, in the above-mentioned synthesis of acrylic resin, the above-mentioned Using the compound shown in (h), a method of competing an acrylic polymerization reaction and a siloxane condensation reaction, or a polymer (silicone resin) having a siloxane bond in the main skeleton by polymerizing a silane compound such as dichlorodimethylsilane by a conventional method. ) Is synthesized, and then the above-mentioned acrylic component is graft-polymerized to the polymer by a conventional method, or an acrylic resin is bonded to the polymer by a conventional method.

In the method of synthesizing an acrylic silicone resin by competing an acrylic polymerization reaction and a siloxane condensation reaction using the compound shown in (h) above, among the total number of monomers used, the compound shown in (h) above The content is preferably 0.2% by mass or more and 15.0% by mass or less, more preferably 0.5% by mass or more and 12.0% by mass or less, and further preferably 0.5% by mass to 3% by mass.

The silicone resin is not particularly limited, but a resin having an unsaturated double bond in the molecular structure, such as an alkyd-modified silicone resin, may be used, or graft polymerization of an acrylic component may be used. May use a monomer other than the acrylic component.

Further, a catalyst may be added to accelerate the reaction between the acrylic component or the acrylic resin and the silicone resin. Here, the catalyst is not particularly limited, but for example, in addition to metal alkoxides (for example, titanium isopropoxide) made of titanium, aluminum, etc., metal acylates and metal chelates, tin compounds, hydrochloric acid, phosphorus, etc. Examples thereof include acids such as acid compounds and carboxyl group-containing compounds, bases such as ammonium, and salts thereof.

The binder resin of the present invention preferably has a glass transition temperature (Tg) of 30 to 60 ° C. When the Tg is less than 30 ° C., the coating films are likely to be fused to each other when the painted roofing material is loaded. On the other hand, when Tg exceeds 60 ° C., the coating film cannot follow the expansion of the base material such as a building material, and the coating film may peel off.

In the present invention, the glass transition temperature (Tg) of the binder resin is calculated by using the following FOX formula.
1 / Tg = W1 / Tg1 + W2 / Tg2 + ... + Wi / Tgi + ... + Wn / Tgn
In the above FOX equation, Tg is the glass transition temperature (K) of the polymer composed of n kinds of monomers, and Tg (1, 2, i, n) is the glass transition temperature (K) of the homopolymer of each monomer. Yes, W (1, 2, i, n) is the mass fraction of each monomer, and W1 + W2 + ... + Wi + ... + Wn = 1.

The binder resin preferably has an acid value of 15 mgKOH / g or more, and more preferably 15 to 100 mgKOH / g.
In the present invention, the acid value of the binder resin is determined by quantifying the number of mg of potassium hydroxide required to neutralize 1 g of the resin.

[Inorganic layered compound]
The inorganic layered compound of the present invention is an inorganic compound in which crystal layers are stacked on each other to form a layered structure. When forming a coating film, the inorganic layered compounds in the coating film are laminated on top of each other to prevent water vapor permeation of the coating film. The effect of improving the property is exhibited, and the moisture resistance and water resistance can be improved. In addition, the layered structure resists the occurrence of warpage of the base material. This resistance is stronger than when the layered compound is contained in the surface coating film.

Here, the layered structure means a structure in which planes (layers) in which atoms are strongly bonded by a covalent bond or the like and are densely arranged are stacked in parallel by a weak bonding force such as a van der Waals force.
The inorganic layered compound of the present invention is at least one surface treatment agent selected from the group consisting of a silane coupling agent, an aluminum-based coupling agent, a zirconium-based coupling agent, and a titanium-based coupling agent, or a condensate thereof. It may be surface-treated with.

Since the inorganic layered compound having such a surface treatment has excellent dispersibility, the water vapor permeability can be significantly reduced. Specifically, a flame-retardant coating film having a film thickness of 40 to 100 μm can be used. 30g ^/ (m 2 · 24h) can be reduced below, this makes it possible to exhibit excellent flame retardancy.

Examples of the surface treatment method for the inorganic layered compound include, but are not limited to, a method in which the inorganic layered compound and the surface treatment agent are charged in a container and heat-treated at 60 to 160 ° C. with stirring. ..

The surface treatment agent may be diluted with a solvent in advance, but it is preferable that the solvent volatilizes after the heat treatment. The amount of the surface treatment agent used is usually 0.3 to 10 parts by mass with respect to 100 parts by mass of the inorganic layered compound, preferably 0.5 to 5 parts by mass depending on the type of the surface treatment agent. used.

Examples of the silane coupling agent that can be used in the present invention include alkyl group-containing silane coupling agents (methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, ethyltrimethoxysilane, diethyldimethoxysilane). , Ethyltriethoxysilane, diethyldiethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, cyclohexylmethyldimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-octyl Trimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, etc.); phenyl group-containing silane coupling agent (n-decyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, etc.); vinyl group-containing Silane coupling agents (vinyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltriethoxysilane, vinylmethyldiethoxysilane, etc.); (meth) acryloyl group-containing silane coupling agents (3-methacryloxypropyltrimethoxysilane, 3- Methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 3-acryloxypropyltri Ethoxysilane, 3-acryloxypropylmethyldiethoxysilane, etc.); Amino group-containing silane coupling agent (3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropylmethyldimethoxysilane , 3- (2-Aminoethyl) Aminopropyltriethoxysilane, 3- (2-Aminoethyl) Aminopropylmethyldiethoxysilane, 3- (2-Aminoethyl) Aminopropylmethyldimethoxysilane, N-β- (N) -Vinylbenzylaminoethyl) -3-aminopropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -3-aminopropylmethyldimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -3 -Aminopropyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -3-aminopropylmethyldiethoxysilane, 3-anilinopropyltri Methoxysilane, 3-anilinopropylmethyldimethoxysilane, 3-anilinopropyltriethoxysilane, 3-anilinopropylmethyldiethoxysilane, etc.); Epyl group-containing silane coupling agent (3-glycidoxypropyltrimethoxysilane) , 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, etc.); mercapto group-containing silane coupling agent (3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, etc.) and the like.

Examples of the aluminum-based coupling agent that can be used in the present invention include acetalkoxyaluminum diisopropinate. Examples of the zirconium-based coupling agent that can be used in the present invention include zirconium stearate. Examples of the titanium-based coupling agent that can be used in the present invention include titanium isostearate, titanium lactate, tetrakis (2-ethylhexyloxy) titanium, titanium-i-propoxyoctylene glycolate, and di-i-propoxy bis. (Acetylacetonato) Titanium and the like can be mentioned.

The above-mentioned silane coupling agent, aluminum-based coupling agent, zirconium-based coupling agent, and titanium-based coupling agent are used in the state of a condensate such as a dimer or a trimer obtained by condensing them. You can also do it. From the viewpoint of workability of surface treatment, the weight average molecular weight of the condensate is preferably 1500 or less.

The inorganic layered compound of the present invention has cleavability, and the inorganic layered compound that can be used in the present invention preferably has a D50 particle size of 1.0 to 200 μm, and has an aspect ratio (major axis / major axis /). The thickness) is preferably 5 to 1500. The D50 particle size is more preferably 0.3 to 45 μm, and particularly preferably 8 to 45 μm.

The D50 particle size of the inorganic layered compound refers to a 50% particle size (D50) of the volume-based particle size distribution, and is a particle size measured using a particle size distribution measuring device (for example, a laser diffraction / scattering type particle size distribution measuring device). It can be obtained from the distribution. The particle size of the inorganic layered compound is represented by the equivalent sphere diameter by the laser diffraction / scattering method.

The aspect ratio of the inorganic layered compound can be determined using a scanning electron microscope (SEM). Specifically, the inorganic layered compound is observed by SEM, the major axis and the thickness of each of the 100 arbitrarily extracted particles of the inorganic layered compound are measured, and then the aspect ratio of each particle is obtained. , Find the average value.

Specific examples of the inorganic layered compound of the present invention include layered silicate, layered graphite, layered chalcogenide, layered hydrotalcite compound, layered lithium-aluminum composite hydroxide, layered zirconium phosphate compound and the like. , Layered silicate is preferred.

Here, the "chalcogenide" is a dichalcogenide of Group IV (Ti, Zr, Hf), Group V (V, Nb, Ta) and / or Group VI (Mo, W) elements, and is of the formula MX _2. (M represents the above element, X represents chalcogen (S, Se, Te)).

Layered silicates generally have a two-layer structure (1: 1 type structure) having an octahedral layer with aluminum, magnesium, or the like as a central metal above the tetrahedral layer of silica, and a tetrahedral layer of silica. However, it is classified into a type having a three-layer structure (2: 1 type structure) in which an octahedral layer having an octahedral layer as a central metal such as aluminum or magnesium is sandwiched from both sides.

Examples of the layered silicate having a 1: 1 type structure include kaolin minerals such as kaolinite and haloysite.
Layered silicates with a 2: 1 type structure are classified according to the difference in layer charge. For example, talc and pyrophyllite have almost no layer charge, and smectites (saponite, herculite, montmorillonite, etc.), vermiculite, and mica (phlogopite, muscovite, sericite) have layer charge. Mica, etc.) and the like.

The layered silicate of the present invention includes not only naturally produced natural products but also artificially synthesized synthetic products. The composite, for example, fluorphlogopite _{(KMg 3 AlSi 3 O 10 F} ), potassium tetrasilisic mica _{(KMg 2.5 Si4O 10 F 2)} , sodium tetrasilicic mica _{(NaMg 2.5 Si 4 O 10 F} 2 ), Sodium teniolite (NaMg ₂ LiSi ₄ O ₁₀ F ₂ ) and lithium teniolite (LiMg ₂ LiSi ₄ O ₁₀ F ₂ ) and other synthetic mica, sodium hectolite (Na _0.33 Mg _2.67 Li _0.33) Si _4.0 O ₁₀ (OH or F) ₂ ), Lithium Hectrite (Li _0.33 Mg _2.67 Li _0.33 Si _4.0 O ₁₀ (OH or F) ₂ ) and Saponite (Na _0.33) Examples thereof include synthetic smectites such as Mg _2.67 AlSi _4.0 O ₁₀ (OH) _2). In the present invention, natural products and synthetic products may be used alone or in combination.

When the layered silicate is in contact with water, it adsorbs water molecules between the layers of the crystal and swells, and then cleaves, and the swellable layered silicate that disperses and disperses in water comes into contact with water. There is also a non-swelling layered silicate that does not change. When a swellable layered silicate is used as the inorganic layered compound, the inorganic layered compound tends to have good dispersibility, is difficult to settle, and has good coating workability.

Examples of the swellable layered silicate include halloysite and smectite as natural products, and the above-mentioned synthetic mica or the above-mentioned synthetic smectite as synthetic products.

The back surface coating film of the present invention preferably contains an inorganic layered compound in an amount of 5 to 35% by mass, more preferably 10 to 30% by mass. One or more kinds of inorganic layered compounds may be mixed and used. By containing 5 to 35% by mass of the inorganic layered compound, excellent water resistance can be obtained and the occurrence of warpage of the base material can be sufficiently suppressed.

≪Additives≫
The back coating of the present invention includes additives commonly used in the paint industry, such as flame retardants, pigments, wetting agents, dispersants, emulsifiers, thickeners, anti-settling agents, anti-skinning agents, and anti-dripping agents. Agents, antifoaming agents, color-coding inhibitors, leveling agents, desiccants, plasticizers, fungicides, antibacterial agents, insecticides, preservatives, light stabilizers, UV absorbers, antistatic agents and conductivity-imparting agents Etc. may be appropriately selected and blended within a range that does not impair the object of the present invention.

≪Cement-based base material≫
Examples of the roofing material of the present invention include roofing materials made of cement-based materials such as concrete roof tiles, asbestos-free decorative slate, and fiber-reinforced cement boards.

The surface texture of the base material is not particularly limited and may have a smooth surface or an uneven shape, but preferably one having fine irregularities improves the adhesiveness of the coating film. It is preferable in terms of improving. Further, the front surface side and the back surface side of the base material may be subjected to a base treatment with a sealer, a primer or the like.

≪Surface side coating film≫
As the surface-side coating film of the present invention, a known surface-side coating film can be used as it is. Moreover, the back surface side coating film of the present invention can also be used as it is.

From the viewpoint of improving weather resistance, the surface-side coating film of the present invention preferably contains at least one resin selected from the group consisting of acrylic resin, urethane resin, acrylic silicone resin and fluororesin. The content of the resin in the surface-side coating film is preferably 50 to 100% by mass.

Further, the surface-side coating film of the present invention may contain a pigment to the extent that transparency is not lost, and may be a color clear layer colored with a pigment or the like depending on a desired design. Examples of the pigment include extender pigments containing a matting agent, colored pigments such as colored pigments, color mica, urethane-based and acrylic-based or transparent beads, scaly graphite, scaly iron oxide, and various pigments such as plated glass flakes. Be done.
≪Additives≫

The surface coating of the present invention includes additives commonly used in the coating industry, such as flame retardants, wetting agents, dispersants, emulsifiers, thickeners, anti-settling agents, anti-skinning agents, anti-sagging agents. Defoamers, color-coding inhibitors, leveling agents, desiccants, plasticizers, fungicides, antibacterial agents, insecticides, preservatives, light stabilizers, UV absorbers, antistatic agents, conductivity-imparting agents, etc. It may be appropriately selected and blended within a range that does not impair the object of the present invention.

≪Characteristics of roofing material≫
In the roofing material of the present invention, the water permeability of the coating film on the back surface side is 2.0 mL / day or less, and preferably 1.0 mL / day or less. Further, the water permeability of the surface coating film is preferably 2.0 mL / day or less, and preferably 1.0 mL / day or less. The water permeation amount of the back surface side coating film is preferably equal to or less than the water permeation amount of the front surface side coating film. The water permeability of the coating film of the present invention can be substantially adjusted by the content of the inorganic layered compound.

≪Manufacturing method of backside coating film and front side coating film≫
The coating film for forming the front surface side coating film and the back surface side coating film of the present invention can be prepared by mixing a binder resin and an inorganic layered compound with various components appropriately selected as necessary, but can be used. A mixed type may be used in which the components to be used are divided into a main agent and a curing agent, and the main agent and the curing agent are mixed and prepared immediately before use.

The binder resin is preferably blended in the form of a solution, emulsion or dispersion. Further, as the paint for forming the coating film, various paint forms such as water-based and organic solvent-based can be used.

As a method for applying the coating material for forming the coating film of the present invention, a conventionally known coating method can be used without particular limitation. Specific examples thereof include a dipping method, a spin coating method, a flow coating method, a roll coating method, a spray coating method, a blade coating method, and an air knife coating method. Of these, the spray coating method and the roll coating method are preferable because the film thickness can be easily controlled, and the roll coating method is more preferable because the effect of pressing the paint into the substrate can be expected.

In these coating methods, a coating film of 4 to 40 μm can usually be formed by one coating, so that the coating is repeated until a desired film thickness is obtained. The back surface side coating film is preferably formed by one or two coatings, and the front surface side coating film is preferably formed by two or more coating films.

The film thickness of the surface coating film of the present invention is 15 to 70 μm, preferably 25 to 60 μm. The film thickness of the coating film on the back surface side is 10 to 120 μm, preferably 25 to 80 μm. When the film thickness of the front surface side coating film and the film thickness of the back surface side coating film are within the above ranges, a coating film having excellent water resistance can be formed, and deformation of the cement-based roofing material can be suppressed.

The present invention will be described in detail with reference to the examples shown below, but the present invention is not limited to these examples. Regarding the description of Examples and Comparative Examples, "parts" and "%" are based on the mass standard.

1. 1. Preparation of front side paint The formulations shown in Table 1 were prepared, and front side paints (A1 and A2) were prepared by a known method. The resin solid content was 30% by mass.
1) Boncoat YG651 (manufactured by DIC Corporation, resin component 47% by mass, MFT 55-60 ° C)
2) Acryset EX-109SI (manufactured by Nippon Shokubai, resin component 40% by mass, MFT 50 ° C)
3) Diamond silica sand No. 8 (manufactured by Okumura Serum)
4) SN Deformer 1316 (manufactured by San Nopco)
5) ASE-60 (manufactured by Rohm and Hearth)
6) Proxel AM (manufactured by Arch Chemicals)
7) TINUVIN1130 (manufactured by BASF)
8) TINUVIN292 (manufactured by BASF)

2. Preparation of backside paint 2-1. Preparation Example of Acrylic Silicone Resin Emulsion EM1 In a reactor equipped with a stirrer, thermometer, cooling tube and dropping device, 22 parts by mass of ion-exchanged water, Latemul PD-104 (trade name, polyoxyalkylene alkenyl ether sulfate ester) Salt: manufactured by Kao Co., Ltd., solid content 20% by mass) 0.8 parts by mass was charged, and the temperature was raised to 80 ° C. while replacing the inside of the reactor with nitrogen, and then potassium persulfate (polymerization initiator) 0. .1 part by mass was added, and subsequently, the raw material emulsion a1 prepared by stirring and mixing in a separate container in advance according to the formulation shown in Table 1 was continuously added dropwise over 3 hours in the total mass part shown in Table 3. After completion of the dropping, the temperature was kept at 80 ° C. for another 2 hours, and then the temperature was lowered to 40 ° C. Next, adjust the pH to 9.0 with 0.26 parts by mass of 25% by mass ammonia water, add 0.02 parts by mass of the defoaming agent and 0.02 parts by mass of the preservative, and add an acrylic resin emulsion having a heating residue of 48% by mass. EM1 was obtained. The resin contained in EM1 is an acrylic silicone resin.

2-2. Preparation of Paints According to the formulation shown in Table 2, each raw material was mixed and then dispersed by a known method to prepare backside paints (B1, B2).

The details of the raw materials described in the table are shown below.
9) R5N (titanium oxide, manufactured by Sakai Chemical Co., Ltd.)
10) Precipitating barium sulfate # 100 (barium sulfate, manufactured by Sakai Chemical Co., Ltd., manufactured by Big Chemie)
11) BYK-181 (dispersant, non-volatile component 50% by mass, manufactured by Big Chemie)
12) VG2 (thickener, non-volatile component 25% by mass, manufactured by ROHM & Haas)
13) SN617 (thickener, non-volatile component 30% by mass, manufactured by San Nopco)
14) BYK-018 (defoamer, non-volatile component 100% by mass, manufactured by Big Chemie)
15) NTS-5 (Inorganic layered compound (sodium tetrasilicon mica, synthetic mica, average particle size 10 to 15 μm, no surface treatment), manufactured by Topy Industries, Ltd.)
16) KBM-403 (silane coupling agent (3-glycidoxypropyltrimethoxysilane), manufactured by Shinetsu Silicone Co., Ltd.)

3. 3. Coating film formation 3-1 Formation of surface coating film Prepare cement-based building materials (molded wood piece cement board mainly composed of cementum and fiber) with a size of 10 cm in length × 10 cm in width × 16 mm in thickness. Was used as a base material test piece.
The above-mentioned surface-side coating compositions of A1 and A2 were coated on the surface side of the substrate test piece with a flow coater so that the film thickness at the time of drying was 15 μm, and dried at 80 ° C. for 5 minutes. This step was performed once more to form a surface-side coating film having a total film thickness of 30 μm when dried.

3-2 Forming the back surface side coating film The above-mentioned B1 and B2 back surface side coating compositions are applied to the back surface side of the base material test piece on which the front surface side coating film is formed, and a roll coater is used on the front surface side of the base material test piece. It was painted so that the film thickness at the time of drying was 35 μm, and dried at 80 ° C. for 5 minutes. This step was performed once more to form a back surface coating film having a total film thickness of 70 μm when dried.
The following evaluation was performed on the obtained test piece. The results are shown in Table 5.

4. Coating film evaluation <Water permeability evaluation>
The water permeability test method was based on JIS A6909 building finish coating material.
Hold the test piece horizontally, fix the water permeability test device with a silicone-based sealant, etc. as shown in Fig. 2, leave it for 48 hours or more, and then test the tap water at 23 ± 2 ° C, which was left in the test room for 24 hours. It is inserted up to a height of about 250 mm from the surface of the body, and the difference between the height of the water head at that time and the height of the water head 24 hours later is defined as the amount of water permeation.
The amount of water permeation is shown by rounding the average value of the three values to one digit after the decimal point. The hydraulic conductivity test instrument can hold a water head of 250 mm, and a funnel with a diameter of about 75 mm and a measuring pipette (capacity: 5 ml) with a scale of 0.05 ml are connected.

<Curved base material>
The test method was based on JIS A5423 Residential roof cosmetic slate.
In the warp test due to water absorption, as shown in FIG. 3, the base point (A, A', B, B'on the back surface of the test piece is 160 mm away from the center point (0) on the back surface side in the direction of two diagonal lines. ) Is provided. Next, the fulcrum of the warp measuring instrument shown in FIG. 4 is applied to the diagonal base point, and the distance between the surface connecting the two base points and the center point is measured using a dial gauge having a scale of 0.01 mm. This is the second measurement. Next, the test piece is immersed about 3 cm below the surface of the water and left for 3 hours. After a lapse of a predetermined time, the test piece is put upright in a dryer adjusted to 80 ± 5 ° C. and dried for 1.5 hours. After that, the test piece is taken out, and the distance between the surface connecting the two base points and the center point is measured again using the measuring instrument shown in FIG. 4, and this is the second measurement. The warp due to water absorption is indicated by the larger of the two diagonal calculation results, which is obtained by subtracting the first measurement value from the second measurement value. Warpage indicates that the surface is convex as positive.

As shown in Table 5, in the sample of the present invention, it can be seen that the amount of water permeation of the coating film on the back surface side is small and the warpage of the base material is improved.

1 Base material 2 Back side coating film 3 Front side coating film Undercoat 4 Front side coating film Topcoat 5 Measuring pipette 6 Rubber tube or vinyl chloride tube 7 Rohto 8 Silicone sealant 9 Test substrate 10 Sample 11 Dial gauge 12 Warp measuring instrument 13 Base point AB'
14 Base point A'-B
15 Test piece (back side)

Claims (4)

A roofing material made of a cement-based base material, which has a front surface side coating film on the front surface side and a back surface side coating film on the back surface side, and at least the back surface side coating film contains an inorganic layered compound. Contains, roofing material. The roofing material according to claim 1, wherein the back surface side coating film contains 5 to 35% by mass of an inorganic layered compound. The water permeability of the front surface coating film is 2.0 mL / day or less, the water permeability of the back surface side coating film is 2.0 mL / day or less, and the water permeability of the back surface side coating film is 2.0 mL / day or less. The roofing material according to claim 1 or 2, which is equal to or less than the water permeability of the above. The roofing material according to any one of claims 1 to 3, wherein the film thickness of the front surface side coating film is 15 to 70 μm, and the film thickness of the back surface side coating film is 10 to 120 μm.

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