JPS61235469A - Production of inorganic binder - Google Patents

Abstract

PURPOSE:To obtain the title binder which does not cause cracking and has excellent spalling resistance, by partially hydrolyzing an alkyl silicate in the presence of a catalyst and polycondensing the partial hydrolyzate in an alcohol at an acidic pH. CONSTITUTION:An alkyl silicate (e.g. methyl silicate) is partially hydrolyzed in the presence of a catalyst composed of silica powder (e.g. fine quartz powder) having an amorphous silica content of 30wt% or below and a tetrahedral structure and polycondensed in an alcohol (e.g. C2H5OH) as a solvent at an acidic pH at 20-60 deg.C for 2-72hr. The reaction mixture is aged and most of solids are cut.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an inorganic binder, and the binder obtained by the present invention has excellent performance as a base for coating materials, adhesives, etc. used in high-temperature atmospheres.

Alkyl silicate esters have been known as binders for inorganic zinc-rich paints, and are mainly used as anticorrosive paints for ships, bridges, etc.

However, conventional products that use as a binder alkyl silicate esters hydrolyzed using acids, alkalis, etc. as catalysts develop tortoise-shell pattern cracks at temperatures above 400°C, and cannot be used as IfI thermal coating materials.

Problems to be Solved by the Invention The present invention solves the above problems and aims to provide a binder that prevents cracking at high temperatures and significantly improves spalling resistance.

Structure of the invention ml, 4. ; [19-L6 Marumu Dando 1 The method for producing the inorganic binder of the present invention is as follows: 1. Silica powder having a tetrahedral structure is added as a catalyst to an alcoholic solution of a partially hydrolyzed alkyl silicate ester, and acidic It consists of condensation polymerization in the region.

The binder composition thus obtained is in the form of a slurry, but a sol-like binder composition can be obtained by carrying out condensation polymerization in an acidic region, aging it, and then carting most of the solid content.

Alkyl silicate ester does not cause cracks, heat! [The following may be the reason why it has not been used in the past as a binder that is resistant to T.

In other words, alkyl silicate esters hydrolyzed with acids, alkalis, etc. cannot completely release the alkyl group at room temperature when condensing and curing, and approximately 600 parts of heating is required to completely release the alkyl group. This is because cracks in a tortoiseshell pattern occur due to hardening and shrinkage.

Therefore, we searched for a catalyst that forms a hexagonal continuum without alJJ, and found that when silica powder with a tetrahedral structure is used as a catalyst, no cracks will occur even when it is heated and cured.
We were able to obtain an inorganic composition with a structure similar to that of a metal crystal.

The silica powder with a tetrahedral structure used as a catalyst here includes fine powders of quartz, cristobalite, phosphorite, etc., and the content of amorphous silica in these catalysts (volume %) is based on the total Ill of the catalyst. It is desirable that the content of amorphous silica is 30% or less; if it exceeds 30%, cracks are likely to occur, so the smaller the content, the more effective it is.

Further, catalysts 11f and 9 preferably account for 50% or less of the total weight of the binder.

Silica not only acts as a polycondensation catalyst, but also partially constitutes a part of the S i 04 '-tetrahedral skeleton produced by polycondensation of hydrolyzed alkyl silicate ester.

The alkyl silicate ester used in the present invention includes:
Examples of the alcohol used as a solvent include methyl silicate, ethyl silicate, butyl silicate, and methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, and amyl alcohol.

In order to produce the binder of the present invention, it is sufficient to simply mix the above-mentioned components and heat and stir the mixture.

Furthermore, white carbon, polyvinyl alcohol, silicone resin, etc. can also be added to this binder.

Regarding the heating temperature, a temperature range of 20°C to 60°C is appropriate; if it is below 20°C, the reaction time will be too long and it will not be commercially viable, and if it exceeds 60°C, the solvent may evaporate and gel. There are many, each of which is undesirable.

The length of stirring time is determined by the temperature and stirring method, but in a temperature range of 20°C to 60°C, 2 hours to 72 hours is an appropriate range.

In order to specifically demonstrate the manufacturing method of the binder according to the present invention and to clarify the characteristics of the manufactured binder, binders having the components of the following examples were prepared, and coating materials for each application example were prepared based on these binders. It was applied to steel plates, heat-resistant bricks, etc., or an adhesive was prepared to bond ceramics together.

Furthermore, a similar coating material and adhesive were prepared using a binder produced by a known hydrolysis method (shown as Comparative Example 1) for comparison.

Example 1 Ethyl silicate (SiOz+40%) 35 parts N15
0 Hydrochloric acid solution (ethyl alcoholic) 35 parts water

3 parts fine powder silica
A total of 100 parts of 27 parts were mixed and heated and stirred at 50° C. for 6 hours to prepare a binder.

Example 2 x4-Rusi+)K-) (S i 02: 40%
) 25 parts N150Jfi acid solution (ethyl alcohol) 50 parts water
3 parts fine powder silica
Total of 22 parts
A binder was prepared by mixing 100 parts and heating and stirring at 50° C. for 6 hours.

Example 3 x4-S iJ K-) (S i 02: 40%
) 35 parts N150 hydrochloric acid solution (ethyl alcoholic)
35 parts water
3 parts fine powder silica
27 parts total
After mixing 100 parts and heating and stirring at 50° C. for 6 hours, more than 98% of the powdered silica was removed to prepare a sol type binder.

Example 4 Ethyl silicate (SiOz: 40%) 25 parts N1
50 hydrochloric acid solution (ethyl alcoholic) 50 parts water

3 parts fine powder silica
222 copies total 10
After heating and stirring at 50°C for 6 hours, more than 98% of the F of the powdered silica was removed to prepare a sol-type binder.

Comparative Example 1 (S i 02: 40)
%) 50 parts ethyl alcohol
44 parts water
5 parts IN hydrochloric acid
1 part total
A binder was prepared by mixing 100 parts and stirring at 20° C. (room temperature) for 48 hours.

Application Examples 1 to 7 and Comparative Application Example 1 Coating materials were prepared using the binders of Examples 1 to 4 and Comparative Example 1 as bases, and the coating materials were coated onto a substrate and their physical properties were measured. The composition of the coating material and the physical properties of the coating are shown in Tables 1 and 2.

Table jj, 2: Cold and hot cycles are 6LIL1 to 2L2
Table fF, 2: As is clear from the results of the 11600-ZUT+ thermal cycle test, the coating material using the binder of the present invention has better heat resistance, thermal shock resistance, and It has excellent water resistance, salt water resistance is excellent, and adhesion is also good.

Application Examples 8 to 10 and Comparative Application Example 2 Adhesives were prepared based on the binders of Examples 1 to 3 and Comparative Example 1, and alumina ceramics were bonded together and their physical properties were measured. Table 3 shows the composition and adhesive properties of the adhesive.

As is clear from the test results in Table 3, the adhesive using the binder of the present invention has much better heat resistance and adhesive strength than the conventional adhesive made using the hydrolysis method of furkyl silicate, and has excellent water resistance. The water resistance and boiling water resistance are also recognized to be good.

By using the binder of the present invention as a composition for coating materials, adhesives, etc., it is possible to combine various functional properties such as heat resistance, thermal shock resistance, corrosion resistance, and boiling water resistance. In addition, it can be combined with other composite materials to function as a composite material, making it possible to produce highly functional paints, coating materials, adhesives, and the like.

Claims (1)

[Scope of Claims] 1. A method for producing an inorganic binder, which comprises adding silica powder having a tetrahedral structure as a catalyst to an alcoholic solution of a partially hydrolyzed alkyl silicate ester and carrying out condensation polymerization in an acidic region. 2. A method for producing an inorganic binder according to claim 1, which comprises carrying out condensation polymerization in an acidic region, aging, and then cutting off most of the solid content.