JPS5838389B2 - Mukitsutsuzokeibutsunokiyoudozoukiyouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for increasing the strength of an inorganic shaped object.

An inorganic shaped article as used in the present invention is one that is shaped or constructed by pouring or pressurizing a mixture obtained by kneading various inorganic powders containing inorganic fibers with water or a binder containing water. Refers to something that has been done.

Conventionally, various inorganic powders and granules have been kneaded with binders and shaped into certain shapes, such as firebricks and furnace materials made from clay and water or fireproof sand, clay and water, gypsum and water, or gypsum and water containing sand. Examples include gypsum boards made from cement and water, sand and jari, or asbestos, cement and water, and molds made from fireproof sand (foundry sand) and binder. Objects generally have low green strength after drying and low residual strength after heating or firing, and are unable to withstand external forces or changes in temperature, and may even break during handling during transportation or transportation.
There are many points that need improvement, such as corners being cut off.

The present invention provides a method for solving the above-mentioned drawbacks, and its first purpose is to increase the green strength of inorganic objects, reduce breakage accidents during handling operations, and improve heating, The purpose is to simplify and speed up post-processes such as firing, curing, etc. The second purpose is to increase the strength of inorganic objects after heating or firing, thereby preventing breakage accidents during transportation and use. The goal is to reduce the amount of damage and give the molded object durability that allows it to be used repeatedly.

The above objects are achieved by the method O of the present invention.

That is, the first aspect of the present invention is obtained by kneading inorganic powder with water or a binder containing water.

A method for increasing the strength of an inorganic shaped article, which comprises impregnating and curing the inorganic shaped article containing free water in its pores with one or more types of general formula silicates; , Rb and RC are the same organic groups as in General 2A above, and Rb and RC are the same organic groups as in General 2A, n is an integer.

) is a method of increasing the strength of an inorganic shaped object and imparting water resistance to it, which is characterized by impregnating and curing a composite silicate prepared by mixing one or more alkoxysilanes represented by the following formula.

To explain this in detail below, the present invention uses various inorganic powders containing inorganic fibers with a binder used in an existing method, such as water or water containing an organic thickening agent.
Targeted inorganic shaped objects formed or constructed by pouring or pressurizing a mixture obtained by kneading water-based colloidal silica, water glass, hydrolyzed solution of silicate ester, etc. with a water-containing binder. In the general formula, ri and n are integers, from immediately after modeling until moisture is removed by complete drying or baking.

) is impregnated with one type or a mixture of two or more types of organic silicates shown in ), and the green strength after drying and the residual strength after heating or sintering are improved by curing.

Examples of the organic silicates used in the present invention include monomers or condensates such as tetramethyl silicate, tetraethyl silicate, tetrabutyl silicate, tetraoctyl silicate, diethyl diisobutyl silicate, and n-butyl tris(β-methoxyethyl) silicate. It can be given as

It is already well known that organic silicates react with water to form anhydrous silicic acid gel or silicic anhydride with a small amount of organic residue, and that when burned at high temperatures of 500°C or higher, highly purified silicic anhydride is produced. .

Therefore, using this, water, a solvent, and an acidic or basic catalyst are added to organic silicate to force a hydrolysis reaction to produce a silicate sol, which is kneaded with inorganic powder and granules, cured, It is already in practical use to bind inorganic powder and granules with silicic anhydride, which is produced through processes such as drying, to make refractories, industrial products, precision molds, heat-resistant paints, etc.

However, in this conventional method, the solvents contained in the silicic acid sol evaporate and cause volumetric contraction, which tends to cause cracks, and the silicic acid sol may not function satisfactorily depending on the conditions of use.

Modeled objects of inorganic powder and granules are made using the solvent (water) of the binder used.
Because there are many continuous pores created by the volatilization of , a certain strength cannot be maintained, and it is possible to increase the strength by filling the pores.

A pattern in which the liquid solidifies within the pores during filling is an ideal filler for enhancing filling.

The organic silicate used in the present invention is exactly the ideal filler.

The present invention impregnates the inorganic shaped article obtained by kneading water or a water-mediated binder and inorganic powder with organic silicate as it is without forcibly hydrolyzing it as in the conventional method. Hydrolysis proceeds slowly due to the moisture remaining in the object and the moisture in the air during curing, and the silicic anhydride produced through a condensation reaction is used in solvents such as water during the formation of the object. The vacancies created by erasure are replenished.

Therefore, excellent effects can be obtained in that the bond between the inorganic powders and granules can be strengthened, and the green strength and the strength after heating or sintering can be greatly improved.

Furthermore, in the present invention, Rh and RC in the organic silicate are the same as the organic groups in the general formula of the organic silicate, and n is an integer.

A method is proposed in which one or a mixture of two or more alkoxysilanes represented by the following formula is impregnated and cured into an inorganic shaped article containing free water in its pores.

According to this method, the alkoxy group of the alkoxysilane is hydrolyzed within the pores of the shaped object, and a condensation reaction proceeds simultaneously.

At this time, since the organic silicate used in combination is also undergoing a similar reaction, it is co-condensed and becomes not just silicic anhydride, but silicic anhydride structured from siloxane chains having an X-Si group, which increases the strength of the inorganic shaped object. It is possible to add water resistance to this at the same time as strengthening it.

The amount of alkoxysilane mixed with respect to organic silicate is 5
φ or more is appropriate.

In the present invention, the organic silicate represented by the above chemical formula or a mixture of this and an alkoxysilane can be impregnated into the object by conventional coating or spraying, by immersing the object in a liquid, or by a method other than atmospheric pressure. This objective can be achieved by any commonly used method, such as a method of promoting permeation by pressurizing or reducing the pressure.

Further, it is also possible to add a surfactant, silicone, or the like to the organic silicate as a penetration aid to provide a means for promoting penetration into the deep part of the shaped object.

Next, the air during the curing period after impregnation can be accelerated not only in the atmosphere but also in a heated and humidified state.

Examples of the present invention will be given below.

Inorganic shaped objects such as industrial products, building materials, and molds have complex shapes and uneven thicknesses, making it difficult to easily measure their strength.

Therefore, in these Examples, inorganic test pieces were prepared using the method described below, and the flexural strength was measured.

The inorganic powder and granules and water or a water-containing binder were thoroughly kneaded, poured into a flat mold of 20 mm x 80 plates x 4 mm, and after curing was dried at room temperature for 3 to 48 hours to obtain a test piece.

Moreover, the bending strength was calculated from.

It goes without saying that the present invention is not limited to the examples listed below.

After kneading, casting and leaving for 24 hours, ethyl silicate 4
The bending strength of the model obtained by immersing it in 0.0 and drying at room temperature for 48 hours was 11.4 kg/1, which was 6.0 kg/1 for the untreated product.
8 kg/cy? It was observed that the strength was improved by about 65 points compared to T&.

Example 2 A model obtained by kneading 100 parts by weight of gypsum with 75 parts by weight of water, leaving the mold for 24 hours, immersing it in ethyl silicate 40 or n-butyl silicate, leaving it at room temperature for 24 hours, and drying. The bending strength of 47. in the case of ethyl silicate 40 treatment. 6 kg/ctrt. , in the case of n-butyl silicate 4 5. 2 kg/=, which is about 50% or about 4 kg/- compared to 31.6 kg/- of untreated material
An increase in strength of 3 yen was observed.

Experimental example: 100 parts by weight of plaster was kneaded with 75 parts by weight of water, and after casting, it was left at room temperature, and after a predetermined time, it was immersed in ethyl silicate 40, and dried at room temperature for 24 hours. The results of comparing the influence of the standing time before soaking were the first.
As shown in the table.

From this result, the bending strength increases as the standing time from casting to immersion increases, and after 24 hours, ethyl silicate 40
It can be seen that the adhesion rate increases rapidly.

Example 3 4 parts by weight of zircon flour with a particle size of approximately 325 mesh and aqueous colloidal silica (trade name Snowtex 30)
1 part by weight is kneaded to form a mold piece, and after being left at room temperature for 3 hours, it is immersed in ethyl silicate 40, isobutyl silicate condensate or monomethyltriethoxysilane,
Table 2 shows the results of comparing the bending strength of the molded product obtained by leaving it to dry at room temperature for 48 hours and the bending strength of the molded product baked for 1000'030 minutes with that of the untreated product.

Example 4 Ethyl silicate 40 (abbreviated as ES-4) used in Example 3
Table 3 shows the green strength and burning strength when these mixtures were used to replace 0) and isobutyl silicate condensate (abbreviated as IBS).

Example 5 Instead of ethyl silicate 40 or n-butyl silicate used in Example 2, 2-ethylhexyl silicate, diethyl dibutyl silicate, methyl tris (β-
When the plaster pieces were impregnated with methoxyethyl) silicate and ethyl cellosolve silicate, the results were almost the same as in Example 2, and the bending strength was improved.

Example 6 Ethyl silicate 1-40 or n- used in Example 2
Ethyl silicate 40 (abbreviated as ESi) and monomethyltriethoxysilane (abbreviated as MTE) were used instead of butyl silicate.
ESi-40 and MT
It can be seen that if ES is used in combination, the strength increase rate becomes rough.

Furthermore, it was found that all of the treated samples were imparted with water resistance.

Claims (1)

[Scope of Claims] 1 An organic silicate that can be expressed by the general formula is added to an inorganic shaped article containing free water in its pores, which is obtained by kneading an inorganic powder or granular material with water or a binder containing water. A method for increasing the strength of an inorganic object, the method comprising impregnating and curing one or more of the following. 2. An inorganic shaped object containing free water in its pores obtained by kneading an inorganic powder or granular material with water or a binder containing water, and RC is the same organic group as in General 2A above, and n is an integer. ) A method for increasing the strength of an inorganic shaped object and imparting water resistance, the method comprising impregnating and curing a composite silicate consisting of an alkoxysilane represented by: