JPS62189B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an inorganic paint composition, and relates to a self-curing inorganic paint comprising an aqueous alkali silicate solution, a hydrous alkali silicate, calcium sulfite and/or calcium thiosulfate, calcium silicate, and alkali-resistant glass fiber. Many inorganic coating compositions using an aqueous alkali silicate solution as a binder have been proposed, but most of them require heat treatment, making it difficult to apply on-site when used as exterior materials for general construction. The applicant has previously proposed an inorganic paint composition that is curable at room temperature and contains a curing agent that exhibits good water resistance and does not cause leaching of alkali carbonates, and that contains an inorganic filler, pigment, etc. 54-66925). By changing the filler in various ways, this composition can be used as interior and exterior materials for general construction, interior materials for tunnels and underground passages, and even as adhesives, but since the entire system is completely inorganic and non-flammable and smokeless, it can be cured by reaction. Occurrence of cracks due to drying shrinkage cannot be avoided to some extent. Therefore, in order to obtain a texture suitable for various uses as a paint, it is necessary to take measures such as selecting the particle size of the filler to minimize cracks. In addition, in order to obtain a coating film with a cosmetic effect, it is possible to use fillers of various particle sizes in combination, but there is a problem that cracks are unavoidable when the coating thickness is at least 1 to 2 mm. . The object of the present invention is to eliminate these drawbacks and provide an inorganic coating composition that provides a high degree of coating film hardness and significantly improves compressive strength, adhesive strength, etc., and does not cause cracks during curing. That is, the present invention provides (A) an alkali silicate; (B) a curing agent comprising calcium sulfite and/or calcium thiosulfate and calcium silicate in a total amount of 30 to 300% by weight based on the solid content of the alkali silicate;
(C) An inorganic filler with a particle size of 2 mm or less, and an alkali-resistant glass fiber having a length of 50 to 300μ in an amount of 5 to 50% by weight based on the total amount of components (A) to (C) above. It is an inorganic paint composition. The alkali silicate of component (A) used in the present invention is preferably _an alkali metal silicate such as sodium, potassium, _or lithium. concentration 10
to 50% by weight) or a powdered alkali hydrohydrate silicate containing 10 to 30% by weight, preferably 15 to 25% by weight of moisture. Hydrated alkali silicate is obtained as an intermediate during the transition from anhydrous alkali silicate to liquid alkali silicate, and has a water content of 10% by weight.
If it is less than 30% by weight, the dissolution rate in water is slow, and if it exceeds 30% by weight, the powder becomes highly sticky and tends to cause blocking. In addition, the average particle size of the powder is preferably 400 μm or less from the viewpoint of miscibility with hardening agents and the like. Also
Component (B), the curing agent, is an essential component, and the absence of these significantly slows down the curing speed, deteriorates water resistance, and causes poor curing at room temperature, making it impossible to work on-site.
In addition, zinc oxide may be used in combination as an auxiliary hardening agent to improve strength. The amount of the above curing agent is based on the alkali silicate solid content of component (A).
If it is less than 30% by weight, curing failure will occur, resulting in a significant decrease in adhesive strength and water resistance, resulting in efflorescence. Also
If it exceeds 300% by weight, the pot life will be significantly shortened and workability will deteriorate. Inorganic fillers for component (C) used in the present invention include silica sand, clay, calcium carbonate, talc, bentonite, diatomaceous earth, kaolin, perlite, shirasu balloons, vermiculite powder, glass beads, etc., and the particle size varies depending on the application. Powders with suitable particle size and particle size distribution can be used accordingly. The blending amount is 100 to 1000% by weight based on the solid content of the alkali silicate. The length and shape of the alkali-resistant glass fiber used in the present invention are 50μ to 300μ, preferably 100 to 200μ.
It is powder-like or cotton-like with a length of μ. If the fiber length exceeds 300μ, not only will dispersion during mixing become poor, but the fibers will be partially exposed on the surface of the resulting coating film, impairing its design. If the length of the fibers is less than 50 μm, the anti-cracking function will be reduced and the result will be similar to that of an inorganic filler. Good effects can be obtained with a blending amount of 5 to 50% by weight based on the total amount of components (A) to (C). If it exceeds 50% by weight, the system will thicken and become difficult to handle. In addition, the composition of the present invention includes methylcellulose as a thickener,
By blending CMC, polyacrylic acid, sodium polyacrylate, etc. to impart appropriate viscosity, it is possible to improve workability and prevent sedimentation of the coating composition. In order to produce the composition of the present invention, it is preferable to mix the alkali-resistant glass fiber with a hardening agent, filler, etc. in advance and then mix it with an alkali silicate at the time of use, since it is curable at room temperature. Furthermore, even if glass fibers are subjected to silane treatment and chromium treatment for adjusting coupling agents, the paint film will not be adversely affected. For application, any coating method can be used, such as spraying, roller coating, troweling, etc. Further, various substrates to which the coating composition of the present invention can be applied include asbestos, slate boards, pulp cement boards, PC boards, ALC boards, plywood, and the like. The coating composition of the present invention has an appropriate pot life and good water resistance by selecting calcium sulfite and calcium silicate as hardening agents for alkali silicate, and also avoids the drawbacks peculiar to inorganic coatings by containing alkali-resistant glass fiber. It is highly effective in preventing the occurrence of hot cracks. That is, in conventional products, the particle size of the inorganic filler used to prevent cracks is limited, and two to three finishing steps are required to obtain a coating film with a thickness of 1 to 2 mm. For example, the particle size of fine powder of silica sand is approximately
When using an inorganic filler of 30μ or less, finishing is required at least twice to prevent cracks. Also, for example, the particle size is 1, such as cold stone.
When using an inorganic filler with a thickness of ~2 mm, a large number of cracks are observed even when the finishing process is performed two or more times. However, when glass fibers are mixed and contained as in the composition of the present invention, an inorganic filler having the above particle size is used, and 1- to
No cracks were observed even when a 2 mm thick coating was formed. Furthermore, the physical properties of the resulting coating film, such as hardness, compressive strength, and adhesive strength, are also significantly improved compared to conventional products. In other words, the coating composition of the present invention not only improves the design as a decorative material, but also simplifies the process, and is also economically advantageous, as the amount of paint used per unit area is reduced due to the inclusion of glass fibers. be. In addition, especially when the ALC board is used as a base material, the surface layer is fragile, and the alkali is neutralized by carbon dioxide gas, sulfur dioxide gas, etc. in the air, and the neutralization of the base material progresses, causing deterioration of the surface layer. In cases where the paint composition of the present invention is applied, it penetrates into the base material and improves the strength of the surface layer, and also acts as a protective film against acidic gases from the outside world, increasing the durability of the base material. It has characteristics such as increasing. The effects of the present invention will be explained below with reference to Examples. Parts and % in each example represent parts by weight and % by weight, respectively. Examples 1-5, Comparative Examples 1-2 40-70 parts of calcium sulfite, calcium silicate
A curing agent consisting of 15 to 16 parts, an inorganic filler shown in Table 1, a pigment, and an alkali-resistant glass fiber (product name: Glass Cut Fiber FESS, manufactured by Fuji Fiber Glass Co., Ltd.) were mixed for 15 minutes in a multipurpose mixer. A curing mixture was prepared. To this was added an aqueous alkali silicate solution or hydrous alkali silicate and water, and the mixture was kneaded for 2 minutes using a lab mixer to obtain an inorganic coating composition. For comparison, a completely similar inorganic coating composition was obtained except that no alkali-resistant glass fiber was added. The methods for measuring these physical properties of the paint are as follows. (1) Crack resistance test - inorganic paint composition with a thickness of 3
A coated plate with a coating thickness of 1 to 2 mm is produced by spraying once on a mm square asbestos slate plate using a spray gun. Immediately after spray finishing at room temperature (20
C) and was continuously exposed to wind at 4 to 5 m/sec for 6 hours to observe the state of cracks in the coating film. Evaluation of cracking resistance test ◎; Hair cracks in the paint film were not observed. After 48 hours, the mold was removed to obtain a 25 mm x 50 mm molded body. After further curing at 20°C for 48 hours, it was tested using a universal testing machine (MU-2 manufactured by Mori Shikenki Seisakusho).
The compressive strength was measured using a mold). (3) Adhesive strength - Apply the prepared inorganic paint composition to a mortar board (70 x 70 x 20 mm) using a spray gun.
After curing for 5 days at room temperature (20°C), measurements were taken using a universal testing machine.

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Claims (1)

[Claims] 1 (A) Alkali silicate (B) 30 in total based on the solid content of the alkali silicate
Hardening agent (C) consisting of ~300% by weight of calcium sulfite and/or calcium thiosulfate and calcium silicate Inorganic filler with a particle size of 2 mm or less 5 to 50% by weight based on the total amount of components (A) to (C) above An inorganic coating composition characterized by containing alkali-resistant glass fibers having a length of 50 to 300μ in weight percent.