JP2002274976A - Method of hardening hydraulic inorganic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a hardened inorganic material which does not occur a dimensional change nor produce effloresence powders in the process of curing and hardening of the hydraulic inorganic material. SOLUTION: This method of hardening the hydraulic inorganic material comprises progressing hardening in the state of applying an aqueous resin dispersion prepared by dispersing a water swellable clay mineral of 1 to 30 μm in average grain size and resin particulates in an aqueous medium at >=0.5 g/m<2> in terms of a solid content to the surface of an unhardened body in hardening the hydraulic inorganic material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a water-curable inorganic material such as cement to produce a cured molded product such as a slate plate, a calcium silicate plate, a calcium carbonate plate, an inorganic board, and a ceramic-based siding board. TECHNICAL FIELD The present invention relates to a method and a method for efficiently curing cement applied in civil engineering work such as road pavement.

[0002]

2. Description of the Related Art Inorganic moldings such as slate boards, calcium silicate boards, calcium carbonate boards, inorganic boards, ceramic-based siding boards, etc. used for external wall materials, etc.
It is formed by molding a water-curable inorganic material such as cement as a raw material into a desired shape and then curing and curing. In order to perform curing and curing efficiently, curing is usually 100
It is general that the process is carried out simultaneously on a large number of inorganic molded bodies stacked and placed in a closed room (autoclave) containing steam under a pressure of ~ 200 ° C. During curing, generation of efflorescence powder from the surface of the molded article (the powder causes poor adhesion between the top coat applied to the molded article and the substrate), and warpage of the molded article Problems such as cracks, dimensional changes, and cracks are likely to occur, and various devices have been devised since ancient times to prevent such problems.

For example, curing after applying a synthetic resin paint to the surface of a molded article is one of the general means for preventing the generation of efflorescence powder and improving the dimensional stability of the molded article. However, in the curing under high temperature in an autoclave, the coating film of the synthetic resin paint is softened, and the stacked molded articles are stuck together, or the coating film is missing when peeling it off. A problem has occurred. In a molded article molded from cement, gypsum, calcium silicate, or the like, problems such as dimensional stability, warpage, and cracks are remarkable. Liquid-type epoxy systems have been applied, but these paints have problems in toxicity and workability. Therefore, although conversion to a water-based paint has been studied recently, a water-based paint having satisfactory performance has not yet been obtained.

Further, in the curing and curing after applying cement or the like to roads or gardens, sufficient moisture cannot be obtained if water disappears from the construction surface due to evaporation, so that the construction surface is hardened while curing proceeds. At present, it is covered with a highly moisturized and hardened woven cloth or a curing mat, and water is sprinkled from there. However, improvement of such a troublesome work has been demanded.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and have completed the present invention. That is, in the first invention of the present invention, when curing the hydraulic inorganic material, the average particle size is 1 to the surface of the uncured body
An aqueous resin dispersion obtained by dispersing a water swellable clay mineral and resin fine particles of 30 μm in an aqueous medium is converted to a solid content of 0.5.
g / m ² or more is a method of curing a hydraulic inorganic material, wherein the curing is advanced in a state of being applied, and the second invention is to form an inorganic molded body by molding and further curing the hydraulic inorganic material. In the production, the water-swellable clay mineral having an average particle size of 1 to 30 μm and resin fine particles are dispersed in an aqueous medium directly or through an undercoating layer on the surface of an uncured or in the middle of curing of a molded article. A method for producing an inorganic molded article, wherein curing is performed in a state where a resin dispersion is applied in an amount of 0.5 g / m ² or more in terms of solid content. Hereinafter, the present invention will be described in more detail. In the following, a feature for preventing the generation of the efflorescence powder may be referred to as an efflorescence resistance.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The hydraulic inorganic material in the present invention is a material which can be cured in the presence of water represented by cement, gypsum, calcium silicate and the like. In the first aspect, when cement is used as the hydraulic inorganic material and the cement is paved on a road or the like, the aqueous resin dispersion, that is, the water-swellable clay mineral having an average particle diameter of 1 to 30 μm and the resin fine particles are dispersed in an aqueous medium. Aqueous resin dispersion (hereinafter simply referred to as "water resin dispersion") dispersed in water is applied to the cement in a state of being applied in an amount of 0.5 g / m ² or more in terms of solid content. In addition, there is no need to cover the concrete surface with a curing mat or the like and occasionally sprinkle water. In other words, the aqueous resin dispersion contains a clay mineral, and therefore, a film formed from the dispersion is difficult for water vapor to pass through, and the concrete surface retains moisture for a period until it hardens. be able to. Concrete cured and hardened under such conditions has sufficient strength. In the curing of road pavement concrete as described above, when the concrete surface is coated with the aqueous resin dispersion, the dispersion may be applied from the initial stage of curing, or after the curing has progressed to some extent. It may be applied.

The aqueous resin dispersion of the present invention comprises a water-swellable clay mineral having an average particle diameter of 1 to 30 μm and resin fine particles dispersed in an aqueous medium as described above. And the above clay mineral. As the synthetic resin aqueous emulsion, an emulsion obtained by emulsion polymerization of styrene, butadiene, ethylene, an alkyl acrylate, or the like in an aqueous medium is preferable. A butadiene emulsion and an ethylene / acrylic acid emulsion; The preferred average particle size of the resin fine particles in the synthetic resin aqueous emulsion is 0.1 to 0.3 μm.

Examples of the water-swellable clay mineral include smectites such as montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, synthetic fluoromica and benite, and in the present invention, synthetic fluoromica is preferred. . Specific synthetic fluorine mica includes sodium tetrasilyl mica, sodium teniolite, lithium teniolite,
Examples include sodium hectorite and lithium hectorite. In addition, the water swelling property is a property of swelling when dispersed in water, and the above water swellable clay minerals have a structurally layered structure, and by coordinating water between layers. It is generally known that they swell (for example, JP-A-6-93133 and JP-A-5-39392). The degree of water swelling used as a measure of water swellability is measured by the Japan Bentonite Industry Association Standard Test Method JBAS-104-77. That is, 2 g of clay powder is added to 100 ml of ion-exchanged water, stirred well, and the volume of the settled portion after 24 hours is measured. Generally, when the volume is 20 ml / 2 g or more, the clay is said to have water swellability.

When the average particle size of the water-swellable clay mineral is less than 1 μm, the obtained inorganic cured product has low mechanical strength, and the inorganic molded product has insufficient efro-resistance.
On the other hand, if the average particle size of the clay mineral exceeds 30 μm, it is difficult to uniformly mix the clay mineral and the aqueous synthetic resin emulsion. The preferred ratio of the resin and the clay mineral in the aqueous resin dispersion is 0.05 to 1 clay mineral per 100 parts by mass of the resin.
50 parts by mass, more preferably 0.05
５０50 parts by mass. It is preferable that a water-soluble polymer is added to the aqueous resin dispersion in addition to the above components in an amount of 0.1 to 50 parts by mass per 100 parts by mass of the resin dispersion. As the water-soluble polymer, polyvinyl alcohol, cellulose derivatives, polyvinylpyrrolidone, polyethylene glycol and the like are preferable. The preferred solid content concentration of the aqueous resin dispersion is 1 to 50% by mass, more preferably 3 to 50% by mass.
20% by mass. If necessary, a coloring pigment, an extender pigment, a filler, an antifoaming agent, and the like may be added to the aqueous resin dispersion.

In the present invention, the aqueous resin dispersion is applied to the surface of an uncured aqueous curable object at a solid content of 0.5 g / g.
m ² or more is applied. The upper limit of the coating amount is about 200 g / m ² from the balance between the effect of coating and the drying time of the coating film. When the amount of coating is less than 0.5 g / m ² , the effect of coating, that is, the mechanical strength of the cured product and the efro-resistance on the surface of the molded product are insufficient. As a coating method, a known method can be employed, and for example, a roller, a brush, an air spray, an airless spray, a shower coat, or the like can be used.

The inorganic molded object of the second invention of the present invention is obtained by molding a water-curable material such as various cements, calcium silicate and gypsum, or a mixture of the material with an aggregate or a reinforcing fiber by a known method. Concrete concrete, cement concrete, cement mortar, ALC (autoclave lightweight concrete), P
C (precast concrete), slate board, calcium silicate board, asbestos cement board, wood chip cement board, pulp cement board, calcium carbonate board, inorganic board, lightweight aerated concrete board, and ceramic siding board. The above-mentioned inorganic molded body can be produced by molding a hydraulic inorganic material into a desired shape and then curing the molded product. The aqueous resin dispersion is applied to the surface of the molded product that is being cured or is being cured. Examples of the molding method of the hydraulic inorganic material include an extrusion molding method, a press molding method, a dry molding method, a cast molding method, and a papermaking method. The aqueous resin dispersion may be applied to the uncured molded body immediately after molding, or if necessary, the initial curing (for example, 4
(A heating at 0 to 100 ° C. for 4 to 20 hours) may be coated with an aqueous resin dispersion.

Before the application of the aqueous resin dispersion, a primer may be applied to the surface of the molded article, if necessary. As the undercoating agent, an organic solvent-based paint or a water-based emulsion-based paint using a urethane resin-based, epoxy resin-based, acrylic resin-based or chlorinated rubber-based film material can be used. Such an undercoating agent has the effect of smoothing the surface of the inorganic molded article to facilitate application of the aqueous resin dispersion, and the effect of reducing the application amount of the aqueous resin dispersion due to its effluent resistance.
The coating amount of the aqueous resin dispersion was 0.5 g / m ^{2 in} terms of solid content.
That is all. When the coating amount is less than 0.5 g / m ² , the efflorescence resistance is poor. The preferable upper limit of the normal coating amount is 5
0 g / m ² . Aqueous resin dispersion to inorganic molded body
Even when the amount of coating exceeds 0 g / m ² , the effect is almost constant, and the blocking resistance is rather lowered. A more preferred coating amount is 10 to 40 g / m ² . As a coating method, in addition to the above-described methods, a dipping method or the like can be used.

After the aqueous resin dispersion is applied to the molded article, a top coat may be applied thereon to improve the appearance. Examples of the overcoat paint include acrylic resin paint, acrylic silicone resin paint, and fluororesin paint having excellent gloss. After all the above paintings are completed,
Further, by curing and curing at 50 to 200 ° C., an inorganic cured molded article is obtained. According to the present invention, the aqueous resin dispersion is applied to a specific amount (0.5 g / m ² or more in terms of solid content) of an uncured molded product. No inorganic form is obtained.

[0014]

The present invention will now be described more specifically with reference to examples and comparative examples.

Example 1 Synthetic fluorine mica having an average particle size of 5.2 μm (water swelling degree: 29 ml / 2 g) was mixed with ion-exchanged water at a solid content of 4%.
After being dispersed at a ratio of mass%, the mixture was heated to 80 ° C. and stirred with a homogenizer for 1 hour. The obtained synthetic fluorine mica dispersion liquid, styrene / acrylate resin aqueous emulsion and polyvinyl alcohol were mixed so that the ratio of synthetic fluorine mica: styrene / acrylate resin water: polyvinyl alcohol = 10: 100: 0.5. By mixing, an aqueous resin dispersion was obtained. This was applied to the following inorganic molded body at a solid content of 20 g / m ^{2 by} spray coating. Inorganic molded body; cement, felt fiber, and water
A mixture prepared by mixing at a ratio of 00 parts by mass / four parts by mass of felt fiber / 35 parts by mass of water to form a flat plate and allowed to stand at room temperature for 30 minutes. Hereinafter, it is referred to as a cement-based board. The cement-based board coated with the aqueous resin dispersion (hereinafter referred to as “treated cement-based board”) was cured in an autoclave (180 ° C., in the presence of water vapor) for 10 hours, but the Efro resistance was good. After leaving the treated cement-based board at room temperature for 2 hours, it was dried with a hot air dryer at 70 ° C. for 20 minutes. After leaving the obtained molded body at 40 ° C. and 95% RH for 24 hours, the dimensional change rate in the length direction was measured, and it was + 0.01%.

[0015]

Comparative Example 1 The same operation as in Example 1 was carried out except that an aqueous styrene / acrylate resin resin-free emulsion containing no synthetic fluoromica was applied to the cement base plate in place of the aqueous resin dispersion in Example 1. Do
Efro-resistance and dimensional change of the molded body were measured. As a result, the efro-resistance is insufficient, and the dimensional change rate is +
0.2%.

[0016]

Example 2 In a room controlled at a temperature of 20 ° C. and a humidity of 60%, a mortar (cement: surface dry sand = 1: 2 and a water / cement ratio of 0.4) was placed on a mold (40 × 40 × 160 mm) in a room. thing)
Was poured and left until the floating water disappeared, and then the aqueous resin dispersion used in Example 1 was applied to the surface of the mortar at a solid content of 50 g / m ² . Next, temperature 23 ° C, humidity 50
%, And the resulting molded body was measured for flexural strength and compressive strength (JIS R).
5201). As a result, the bending strength was 6.2 N / mm ² and the compression strength was 24 N / mm ² . These strengths are almost at the same level as those of cured products obtained by curing at a temperature of 23 ° C. and a humidity of 100%.

[0017]

According to the present invention, an extremely simple operation of applying an aqueous resin dispersion to an inorganic molded article or the like can be achieved by:
It is possible to create a favorable environment for curing the molded body,
The dimensional change of the inorganic molded body during curing is small, and the obtained molded body is excellent in the Efro resistance. Furthermore, the cured product obtained by the present invention has excellent mechanical strength.

Claims (4)

[Claims] 1. In curing a hydraulic inorganic material,
A state in which a water-swellable clay mineral having an average particle size of 1 to 30 μm and an aqueous resin dispersion obtained by dispersing resin fine particles in an aqueous medium are applied to the surface of the uncured material in an amount of 0.5 g / m ² or more in terms of solid content. A method for curing a hydraulic inorganic material, wherein the curing is progressed by: 2. In producing an inorganic molded article by molding and further curing a hydraulic inorganic material, an average particle size of the uncured or in the course of curing is 1 μm directly or via an undercoat paint layer. An inorganic resin characterized in that curing proceeds in a state where an aqueous resin dispersion obtained by dispersing a water-swellable clay mineral and resin fine particles of about 30 μm in an aqueous medium is applied in an amount of 0.5 g / m ² or more in terms of solid content. A method for producing a molded article. 3. The method for curing a hydraulic inorganic material according to claim 1, wherein said water-swellable clay mineral contains an elemental fluorine. 4. The method according to claim 2, wherein the water-swellable clay mineral contains elemental fluorine.