JP2005089567A - Coating method and undercoating for cement base material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an undercoating film formed on a cement base material and excellent in adhesiveness. <P>SOLUTION: An undercoating which is applied to a cement base material and prepared by the copolymerization of an acrylic emulsion monomer and 5-50 mass% CHMA is provided. A coating method for a cement base material comprising coating the cement base material with an undercoating prepared by the copolymerization of an acrylic emulsion monomer and 5-50 mass% CHMA, conducting high-temperature high-pressure aging, and after the completion of the aging, coating the cement base material with a finish coating material comprising a CHMA-copolymerized acrylic emulsion is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for coating various cement products and an undercoat used therefor.

  Cement-based building materials such as new roof tiles, thick slate and siding board harden the cement by cement hydration reaction, but long-term curing is required for hydration reaction at room temperature or Since there is a possibility that problems such as occurrence of a sense may occur, a process of accelerating the hydration reaction by high temperature and pressure such as autoclave curing and steam curing is performed to prevent these problems.

  When applying to these cement-based building materials, by applying the undercoat before the curing, forced drying and film formation can be efficiently performed using the high temperature during curing. Conventionally, acrylic emulsion resin paints and styrene-acrylic copolymer emulsion resin paints have been widely used as undercoat paints for cement-based building materials from the viewpoints of cost and coating film performance.

On the other hand, an acrylic emulsion resin coating copolymerized with cyclohexyl methacrylate (hereinafter referred to as “CHMA”) has recently been used as a top coating for cement-based building materials, focusing on the excellent durability and weather resistance of coating films. It has become like that. When evaluated as a single coating, the CHMA acrylic emulsion resin is very good, but the conventional primer coating, acrylic emulsion resin coating, styrene-acrylic copolymer emulsion resin coating, and adhesion between coating layers The disadvantage of poor nature was found.
In addition, there is no delamination of the coating layer applied to the ceramic exterior building material, there is little precipitation of ephro from the ceramic exterior exterior building material, it is excellent in weather resistance, water resistance, alkali resistance, and can maintain aesthetics for a long time. For the purpose of exterior building materials, an exterior building material having at least two layers of an aqueous paint coating layer containing a polymer having a cyclohexyl group on the surface of a ceramic-based exterior building material is disclosed in Japanese Patent Application Laid-Open No. 2000-160095. Yes.
JP 2000-160095

  Therefore, an undercoat with excellent adhesion for using an acrylic emulsion copolymerized with CHMA that is excellent in cost and excellent in coating film durability as a top coat for cement-based building materials, and a coating method using this undercoat Is the subject of the present invention.

  As a result of diligent research, the present inventor has focused on autoclave curing and steam curing, which are usually performed in the production process of cement-based building materials, and applied an undercoat of a specific component before these curing processes. By doing this, it has been found that an undercoat coating film having excellent adhesion can be formed, and the gist thereof is as follows.

An undercoat paint to be applied to a cement substrate, wherein 5 to 50% by mass of CHMA is copolymerized with respect to an acrylic emulsion monomer.
A cement base material is coated with 5 to 50% by mass of CHMA with respect to the acrylic emulsion monomer. After the primer coating for cement base material is applied, high temperature and high pressure curing is performed. A method for coating a cement base material, comprising applying a top coat paint for a cement base material comprising a polymerized acrylic emulsion.
This will be described in detail below.

  As a cement-based building material to which the present invention can be applied, by adding water to a cement-based material such as Portland cement, alumina cement, blast furnace cement, blast furnace slag, calcium silicate, gypsum, etc., it hardens by a hydration reaction, It is formed into an arbitrary shape. An inorganic filler and a fiber material are appropriately added to the cement material to increase the strength of the building material. Typical examples include roofing materials represented by tiles such as new roof tiles and thick slate, and building exterior materials such as siding boards.

  The above-mentioned cement-based building materials can be arbitrarily mixed with necessary cement-based materials, if necessary, by mixing and kneading various fillers, fibers and water, and by molding methods such as extrusion molding, cast molding, papermaking molding, and press molding. Molded into a shape. An undercoat paint according to the present invention is applied to the molded cement-based building material.

  It is essential that the undercoat paint is copolymerized with 5 to 50% by mass, preferably 10 to 35% by mass, of CHMA with respect to the acrylic emulsion monomer. When the CHMA is less than 5% by mass, the effect of improving the adhesion with the CHMA copolymer acrylic emulsion top coating is not sufficient. Further, even if CHMA is copolymerized in an amount exceeding 50% by mass, the effect of improving the adhesion with the CHMA copolymerized acrylic emulsion top coat is not changed, but rather the cost as an undercoat is increased, which is economically disadvantageous. .

As the formulation of the undercoat paint, any so-called clear paint containing no pigments, a color clear paint obtained by translucently coloring the clear paint, and a so-called enamel paint containing a colored or extender pigment can be used.
The method of applying the undercoat paint is not particularly limited, and a coating method conventionally applied to cement-based building materials is possible. That is, brush coating, roller coating, air spray coating, airless spray coating, roll coater, curtain flow coater, reduced pressure coating, and the like.

  The cement-based building material coated with the undercoat of the present invention enters a high-temperature and high-pressure curing process such as autoclave curing and steam curing. The effect of the present invention can be obtained even at room temperature curing in which curing is performed at room temperature for a long time.

  After the undercoat paint film is formed on the cement-based building material by the curing process, the topcoat paint with the CHMA copolymer acrylic emulsion is applied. The method for applying the top coating is not particularly limited, and brush coating, roller coating, air spray coating, airless spray coating, roll coater, curtain flow coater, reduced pressure coating, and the like are applicable. After the top coating is applied, a coating film is formed at room temperature or by forced heating drying.

  The undercoat paint according to the present invention has high hydrophobicity due to CHAM, and is highly effective in preventing the occurrence of efflorescence. Moreover, the acrylic emulsion copolymerized with CHMA is excellent in hydrolysis resistance and highly stable against the strong alkalinity of the cement base before curing. Furthermore, by using a CHMA copolymer acrylic emulsion in the topcoat, the compatibility at the interface is very close due to the approximation of the composition of both the basecoat and the topcoat. Adhesion increases, and a very strong protective coating film is formed on cement-based building materials as a whole.

  In order to provide an understanding of the present invention, examples are described below. Needless to say, the present invention is not limited to the following examples.

CMA / MMA / BA copolymer resin emulsion containing 5% by mass of CHMA and having a Tg point of 30 ° C. as a primer for cement roof tiles, a reactive anion as an emulsifier, and ethylene glycol monobutyl ether as a film-forming aid 1 (clear) was produced, and the undercoat 1 was applied to the cement roof tile with a vacuum coater. After painting, it was carried into an autoclave curing chamber and subjected to autoclave curing in 180 ° C. saturated steam for 4 hours.
After the curing, CHMA 30% by mass as a top coating for cement roof tiles, a CHMA / MMA / BA copolymer resin emulsion having a Tg point of 30 ° C., a reactive anion as an emulsifier, ethylene glycol monobutyl ether as a film-forming aid, A top coating 1 (enamel), in which titanium oxide (white) and carbon black (black) were added and mixed as coloring pigments, was coated with a reduced pressure coating machine, and then a top coating film was formed by heating and drying.

CMA 15% by mass CHMA / MMA / BA copolymer resin emulsion containing CMA / MMA copolymer resin emulsion, reactive anion as emulsifier, and ethylene glycol monobutyl ether as a film-forming aid (Clear) was manufactured, and the undercoat paint 2 was applied to the cement roof tile with a vacuum coater. After painting, it was carried into an autoclave curing chamber and subjected to autoclave curing in 180 ° C. saturated steam for 4 hours.
After completion of the curing, the top coating material 1 (enamel) was applied with a reduced pressure coating machine as a top coating material for cement roof tiles, and then a top coating film was formed by heat drying.

CMA / MMA / BA copolymer resin emulsion containing 25% by mass of CHMA as an undercoat paint for cement roof tiles, Tg point 30 ° C., reactive anion as an emulsifier, and ethylene glycol monobutyl ether as a film-forming aid 3 (Clear) was manufactured, and the undercoat paint 3 was applied to the cement roof tile with a vacuum coater. After painting, it was carried into an autoclave curing chamber and subjected to autoclave curing in 180 ° C. saturated steam for 4 hours.
After completion of the curing, the top coating material 1 (enamel) was applied with a reduced pressure coating machine as a top coating material for cement roof tiles, and then a top coating film was formed by heat drying.

Comparative example

[Comparative Example 1]
As an undercoat paint for cement roof tiles, an undercoat paint 4 (clear) containing CHMA-free MMA / BA copolymer resin emulsion having a Tg point of 30 ° C., an anion as a reactive anion, and ethylene glycol monobutyl ether as a film-forming aid. The undercoat paint 4 was manufactured and applied to the cement tile with a vacuum coater. After painting, it was carried into an autoclave curing chamber and subjected to autoclave curing in 180 ° C. saturated steam for 4 hours.
After completion of the curing, the top coating material 1 (enamel) was applied with a reduced pressure coating machine as a top coating material for cement roof tiles, and then a top coating film was formed by heat drying.

[Comparative Example 2]
As an undercoat paint for cement roof tiles, a styrene / MMA / BA copolymer resin emulsion with a Tg point of 30 ° C. that does not contain CHMA, a reactive anion as an emulsifier, and ethylene glycol monobutyl ether as a film-forming aid (clear) And the undercoat paint 5 was applied to the cement roof tile with a vacuum coater. After painting, it was carried into an autoclave curing chamber and subjected to autoclave curing in 180 ° C. saturated steam for 4 hours.
After completion of the curing, the top coating material 1 (enamel) was applied with a reduced pressure coating machine as a top coating material for cement roof tiles, and then a top coating film was formed by heat drying.

result
(1) The surface of the coated film after autoclave curing was observed to examine whether or not efflorescence was generated.
Example 1 to Example 3: No occurrence of efflorescence Comparative Example 1: Occurrence of a large amount of efflorescence Comparative Example 2: No occurrence of efflorescence
(2) Each coated tile was dipped in 60 ° C. warm water for 3 days after the top coat was dried and left at room temperature, and then a peel test was performed with an adhesive tape. The delamination area between the undercoat film and the topcoat film is less than 10%: Pass 10% or more: Fail.
Example 1: Peeling rate 5% (pass)
Example 2: Peeling rate 2% (pass)
Example 3: Peeling rate 0% (pass)
Comparative Example 1: Peeling rate 27% (failed)
Comparative Example 2: Peeling rate 38% (failed)

  The present invention eliminates the occurrence of efflorescence even when autoclave curing, which improves product stability and production efficiency, is performed on cement building materials such as new roof tiles, thick slate, and siding board. The interlayer adhesion between the undercoat film and the topcoat film is remarkably improved, which greatly contributes to improving the finished quality of cement-based building material products.

Claims (2)

An undercoat paint for coating on a cement base material, wherein 5-50% by mass of cyclohexyl methacrylate (CHMA) is copolymerized with respect to an acrylic emulsion monomer. After the base material for cement base material is coated with 5-50% by mass of cyclohexyl methacrylate (CHMA) to acrylic emulsion monomer on the cement base material, high-temperature and high-pressure curing is performed, and the curing is completed. A method for coating a cement base material, which is followed by applying a top coat paint for a cement base material comprising a cyclohexyl methacrylate (CHMA) copolymer acrylic emulsion.