JPH11322472A - Reinforcement of surface of inorganic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reinforce the surface of an inorg. substrate contg. a calcium silicate compd. in the surface layer and having a roughened surface due to the compd. so that the substrate is made excellent in durability and adhesion to a film of a finish coating material. SOLUTION: The surface of an inorg. substrate contg. a calcium silicate compd. in the surface layer and having a roughened surface due to the compd. is reinforced by applying and drying an aq. emulsion as a primer. The aq. emulsion is prepd. by dispersing a liq. resin having 10<-2> -10<1> Pa.s viscosity at 80 deg.C and 10<8> -10<10> Pa elastic modulus at 25 deg.C after drying solidification in water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reinforcing a surface of an inorganic base material used for a roof tile, a wall material, a floor material and the like.

[0002]

2. Description of the Related Art Inorganic materials such as calcium silicate boards and cement boards have excellent durability and fire resistance and are widely used as building materials such as roof tiles, wall materials and floor materials. There is known a method of applying using two kinds of paints, an undercoat paint mainly for reinforcing the surface of the inorganic base material and an overcoat paint mainly for improving the aesthetic appearance.

[0003] For example, Japanese Patent Publication No. Sho 62-50436 describes a method of applying an epoxy powder paint as a base coat and an acrylic powder paint as a top coat. There is disclosed a method of applying an undercoat using an acrylic emulsion resin, an epoxy emulsion resin, and cement, and a top coat using an acrylic polyol resin and a silicone resin.

[0004] In order to apply a powder coating or a coating containing an inorganic material as disclosed in any of the above publications, the equipment scale is large and the cost is high. Further, there is a problem that a spray coating method suitable for an object having a complicated shape cannot be adopted. An undercoat using an aqueous emulsion containing no inorganic material is also known (see, for example, Japanese Patent Application Laid-Open No.
However, it is difficult to control the impregnation, retention, and curing of the calcium silicate layer, and as a result, it was not possible to obtain a material excellent in adhesion and durability.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object the presence of a calcium silicate compound in a surface layer, which compound makes the surface of a substrate rough. It is an object of the present invention to provide a reinforcing method for an inorganic base material, which has excellent adhesion and durability to a coating film formed by a top coat.

[0006]

According to a method of coating an inorganic substrate of the present invention, a calcium silicate compound is present in a surface layer;
A resin liquid having a viscosity of 10 ⁻² to 10 ¹ Pa · s at 80 ° C. and an elastic modulus after drying and solidification of 10 ⁸ to 10 ¹⁰ Pa at 25 ° C. is applied to the inorganic substrate whose surface is roughened thereby. The surface is reinforced by applying and drying an aqueous emulsion obtained by dispersing in water as an undercoat paint.

The inorganic substrate to be used in the present invention may be any one in which a calcium silicate compound is present in the surface layer.
Other substances may be mixed inside the base material. In general, an inorganic substrate is formed by a method such as press molding, extrusion molding, and sheet molding. Usually, steam curing or autoclave curing is performed after molding in order to improve strength and dimensional stability. Although there are differences depending on the conditions such as the type, blending, and curing of the material, a calcium silicate compound may appear on the surface in this step.

In such a case, the calcium silicate compound does not exist in the inorganic substrate surface layer before curing, but appears in the substrate surface layer after curing. The calcium silicate compound appearing on the surface layer can be confirmed with a scanning electron microscope. This compound is in the form of a needle having a width of 0.001 μm to 0.3 μm and a length of 0.5 to 5 μm, or a width of 0.3 to 10 μm.
In the form of a plate having a length of 10 μm. These are arranged in a state where a large number of voids are formed so as to overlap with each other on the substrate surface layer, whereby the surface of the substrate becomes rough. When calcium silicate has high crystallinity, it is a compound called tobermorite or etlitnite, and may be identified by wide-angle X-ray diffraction or the like in some cases.

Among the above, the inorganic base material that particularly exhibits the effects of the present invention has a width of 0.01 to 0.1 μm and a length of 0.1 to 0.1 μm.
This is the case where an acicular calcium silicate compound having a size of 5 to 5 μm is present in the surface layer.

The water-based emulsion paint used in the present invention is:
Viscosity at 80 ° C is 10^-2-10 ¹Tree that is Pa · s
It is obtained by dispersing a fat liquid in water. The preferred viscosity is 5 × 10
^-2-10⁰Pa · s. Viscosity is 10^-2From Pa · s
Low, penetrate and pass through the calcium silicate compound layer
And stays and solidifies in the layer to reinforce the surface.
I can't. Also, 10¹In the case of viscosity exceeding Pa · s
Cannot penetrate the calcium silicate compound layer,
Deposits on the layer, reinforcing the surface of the substrate
Can not be obtained.

The viscosity of a water-based emulsion paint is as follows:
Generally adjusted by changing the emulsion resin concentration
can do. Easy to apply the target amount evenly
The viscosity as a paint at 80 ° C.
Preferably 5 × 10^-Four-10 ^-2Pa · s. Resin liquid
Is measured using, for example, a cone-disk rheometer.
Can be measured. Measurement shear rate is 10^Twos^-1And

The water-based emulsion paint used in the present invention has an elastic modulus after drying and curing of 10 ⁸ to 10 ¹⁰ P at 25 ° C.
It is obtained by dispersing the resin liquid as a in water. A preferable elastic modulus is 10 ^{9 to} 5 × 10 ⁹ Pa. If the elastic modulus is lower than 10 ⁸ , the impregnated and cured coating film is too soft and the reinforcement of the calcium silicate layer is insufficient, so that 10 ¹⁰ Pa
If it exceeds 300, the impregnated coating layer will be too hard and brittle, and the reinforcement of the calcium silicate layer will be insufficient.

[0013] The measurement of the elastic modulus is performed by applying an undercoat paint on a metal plate or the like, drying and solidifying to form a film-like coating film.
The coating is performed according to JIS K7113. The strain rate during measurement is 1 s ^-1 .

The undercoat paint of the present invention may be a one-pack type or a two-pack type. In the case of the two-liquid mixing type, the viscosity of the resin liquid constituting each aqueous emulsion paint must be 10 ^-2 to 10 ¹ Pa · s.

When the resin liquid is dispersed as an aqueous emulsion, an emulsion stabilizer can be added. The particle size of the emulsion is not particularly limited, but is 0.01 to 10 μm.
Is preferred.

Examples of the undercoat paint which satisfies the above-mentioned physical properties include, for example, a two-liquid mixed type of a combination of an aqueous emulsion of an epoxy resin and an aqueous emulsion of a polyamine whose molecular weight and structure are controlled.

In the present invention, since the above-mentioned undercoat is applied to an inorganic substrate having a calcium silicate compound present in the surface layer, the undercoat is present in the mechanically weak calcium silicate layer existing in the surface layer of the substrate. Without passing through
Strengthening by infiltration / retention / solidification in the layer. As a result, a material having excellent adhesion and durability to the coating film of the overcoat paint applied thereon can be obtained.

The method of applying the undercoat paint is suitable for coating a substrate having a complicated shape by air spray coating or airless spray coating. However, a known method such as roller coating or carton coater coating may be used.

The top coat to be applied on the undercoat may be appropriately selected and used. In the case of a water-based emulsion paint, a mixture of an acrylic resin, a urethane resin, a fluororesin and the like with an inorganic pigment is often used. The method of applying the top coat can be performed in the same manner as in the case of the undercoat. The top coat may be applied after drying and solidifying the undercoat, or may be applied without drying and solidifying after applying the undercoat.

[0020]

Embodiments of the present invention will be described below. Incidentally, as the inorganic base material used in Examples and Comparative Examples,
After steam curing, the autoclave-cured calcium silicate plate (substrate 1) having the surface state as shown in the micrograph of FIG. 1 and the calcium silicate plate (substrate 2) as shown in the micrograph of FIG. Two types were used. The shape of the calcium silicate crystal in each surface layer was as follows. Base material 1: about 0.01 μm in width and about 2 μm in length Base material 2: about 0.3 μm in width and about 2 μm in length

(Example 1) A two-component mixed paint of a bisphenol A type epoxy resin aqueous emulsion and an aromatic polyamine aqueous emulsion was used as an undercoat.
The viscosity of the epoxy resin liquid constituting the aqueous emulsion is 8
At 0 ° C., it was 7.4 × 10 ⁻² Pa · s. Similarly, the viscosity of the aromatic polyamine constituting the water-based emulsion is 1.
It was 2 × 10 ⁻¹ Pa · s. The two liquids were mixed, applied to a glass plate with a bar coater, and dried at 30 ° C. to obtain an undercoat film. This is in accordance with JIS K7113, 25 ℃
Was 2.5 × 10 ⁹ Pa.

The above two types of aqueous emulsion mixtures were applied to the substrate 1 heated to 85 ° C. with an airless gun so that the solid content was 5 g / m ² . Subsequently, an existing acrylic emulsion paint (manufactured by Daicel Chemical Co., Ltd., trade name “Sebian A”) was applied with an airless gun so that the solid content was 15 g / m ^2, and a film was formed in an air jet incinerator at 100 ° C. .

(Example 2, Comparative Examples 1 to 5) Table 1 shows the viscosity of the epoxy resin liquid, the viscosity of the polyamine, and the inorganic base material.
The coating was carried out in the same manner as in Example 1 except that the one shown in (1) was used.

As described above, the following tests were conducted for the examples and comparative examples. (1) Adhesion test: After painting, after storing in a constant temperature and high humidity room at a temperature of 23 ° C. and a humidity of 50% for 3 hours, wipe off dust and dirt with a cotton cloth and attach a cloth tape (manufactured by Sekisui Chemical Co., # 600). And rubbed with a cotton cloth. After leaving for 6 hours, the state of the painted surface after peeling off the cloth tape with full force was observed. (2) Freeze-thaw test: based on ASTM C1185,
-20 ° C and 20 ° C were repeated for 100 cycles, and the state of the painted surface was observed. Table 1 shows the above results.

[0025]

[Table 1]

[0026]

According to the method for reinforcing the surface of an inorganic substrate of the present invention, a calcium silicate compound is present in a surface layer, and the surface of the substrate is roughened by the compound.
An undercoat paint, which is an aqueous emulsion obtained by dispersing a resin liquid having a viscosity at 0 ° C of 10 ^-2 to 10 ¹ Pa · s and an elastic modulus after drying and solidification of 10 ⁸ to 10 ¹⁰ Pa at 25 ° C in water. Is applied, the undercoat paint penetrates, stays, and solidifies in the surface layer of the substrate, thereby strengthening the substrate surface layer. As a result, the adhesiveness to the coating film formed by the top coat and the durability are excellent. Therefore,
It is most suitable as a method for reinforcing the surface of inorganic base materials used for roof tiles, wall materials, floor materials, and the like.

[Brief description of the drawings]

FIG. 1 is a micrograph of a substrate 1 taken from above.

FIG. 2 is a micrograph of a substrate 2 taken from above.

Claims (3)

[Claims] 1. A calcium silicate compound is present in a surface layer, so that an inorganic substrate having a roughened surface is
An aqueous emulsion obtained by dispersing a resin liquid having a viscosity of 10 ⁻² to 10 ¹ Pa · s at 25 ° C. and an elastic modulus after drying and solidification of 10 ⁸ to 10 ¹⁰ Pa at 25 ° C. in water is applied as an undercoat paint. -A method for reinforcing the surface of an inorganic substrate, wherein the surface is reinforced by drying. 2. The method for reinforcing the surface of an inorganic substrate according to claim 1, wherein the inorganic substrate is an autoclave-cured calcium silicate plate. 3. The method for reinforcing a surface of an inorganic substrate according to claim 1, wherein the aqueous emulsion is a two-part mixed type emulsion of an aqueous epoxy resin emulsion and a polyamine aqueous emulsion.