JPS6183667A - Manufacture of heat resistant molded body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a heat-resistant molded article, particularly a low-specific gravity heat-resistant molded article having a specific gravity of about 0.5 or less and good heat insulation properties. It is.

Orai's technology As a heat-resistant molded body with a low specific gravity used for insulation materials, etc. (the calcium silicate molded body is a typical example), the manufacturing method is to use silicate raw materials and calcareous raw materials. It has been practiced since early times to heat and react with reinforcing asbestos and a large amount of water under normal pressure, mold it, and then heat it in an autoclave to harden it. However, in addition to requiring a large number of steps and complicated operations, it also has the disadvantage of requiring a large autoclave for steaming the molded product.As an alternative manufacturing method, the method for manufacturing calcium silicate molded bodies has become popular in recent years. prepared a calcium silicate hydrate crystal slurry by heating silicic and calcareous raw materials together with water under pressure in an autoclave, and added a small amount (usually A mixture of reinforcing #5 fibers (approximately 1 to 5% by weight) is dehydrated and molded and dried.This method can also produce moldings with a very low specific gravity close to 0.1. However, the preparation of calcium silicate hydrate crystals, which account for most of the molding raw material, requires expensive autoclay 7 and a large amount of thermal energy, and the calcium silicate hydrate is expensive. The disadvantage is that the manufacturing cost is high due to the poor freeness of the crystals and the time required for dehydration and molding.Additionally, the shrinkage during the drying process of the dehydrated moldings is large, making it difficult to achieve dimensional accuracy of the product. When molded using a press molding method using a mold, the mold release property is poor.
For this reason, another drawback is that the product tends to have misshapen corners and the like. As for the product, it has insufficient flexibility and is prone to cracking and chipping of corners, and when heated above the crystal transformation temperature, a significant decrease in strength and cracking of the heated surface occur, and depending on the crystal form, carbonation may occur. It has been pointed out that this causes significant shrinkage cracks as a problem.

On the other hand, there is a known method of bonding one layer of inorganic fibers such as rock wool, lath fiber, silica fiber, ceramic fiber, silica fiber, etc., to form the fiber, and this method is generally carried out before the fiber hardens. Since the green strength of the molded product is low, handling properties during the drying or firing process are very poor, and it is difficult to obtain a molded product with good dimensional viscosity. In addition, the products generally have low compressive strength and may break during construction, and furthermore, they have the disadvantage of deformation and significant decline in strength at high temperatures.

In addition, in Japanese Patent Publication No. 5O-2 = 497S, active sea 7
Trit slurry and P-free itrade fiber are mixed at a ratio of about 30 to 90% (in terms of solid content) of the former and about 70 to 10% of the latter, which is further mixed with water, and the resulting slurry is made into paper. This method describes a method for manufacturing a non-synthesizing fiber board for construction by heating and pressurizing it, but although this manufacturing method can manufacture a thin plate, as mentioned above, the filtration of xonotlite is Because the water resistance is not good, it is a thick plate with a thickness of 20 mm or more that can be used as a heat insulating material. Construction is extremely difficult.

Furthermore, Japanese Patent Publication No. 53-18533 discloses that a calcium silicate hydrate crystal slurry is prepared by heating a silicate raw material, a calcareous raw material, and a reinforcing inorganic fiber together with water under pressure while stirring in an autoclave. A method is described in which a molded body is obtained by dehydrating and molding this and drying it, but this manufacturing method requires autoclaving the reinforcing material (!!5.m) together with the raw material for producing calcium silicate. Therefore, in addition to requiring a large autoclave and increasing the thermal energy cost, it also requires autoclaving together with calcareous materials. This method has some disadvantages over the conventional method using the calcium silicate hydrate crystal slurry. And as stated in the same bulletin,
When the reinforcing fiber is: Fi cotton, a remarkable improvement in heat resistance strength is achieved by directionally bonding sheet 7 trite crystals to the fiber surface, but when rock wool is used, Such effects are not trivial, and now that the use of asbestos has been restricted, there are few advantages to this manufacturing method.

The fundamental invention that the invention attempts to solve is that the conventional method for producing a heat-resistant molded article with low specific gravity is one that requires improvement, as described above, as described above. The aim is to provide a manufacturing method that is more advantageous than conventional manufacturing methods in many respects, such as productivity, product quality, and so on.

The means adopted in the present invention to solve the above problems is to prepare a calcium silicate hydrate crystal slurry from a silicic acid raw material and a calcareous raw material. Mixing the slurry of calcium silicate hydrate crystals with vitreous water to produce vitreous fibers containing 5 to 150 parts by weight of calcium silicate hydrate crystals per part by weight. A slurry to be prepared is prepared, a bottomed polymer flocculant and a fixing agent are added to this slurry, and the solid raw materials are agglomerated by two steps, followed by dehydration molding. It consists of drying the moldings obtained.

The manufacturing method of the present invention will be explained in detail below.

In the production method of the present invention, first, a siliceous raw material is prepared by a conventional method.
A calcareous raw material and water are stirred in an autoclay 7 and subjected to a hydrothermal reaction to produce a calcium silicate hydrate crystal slurry 'A, or the calcium silicate hydrate crystals produced in this step are xonotlite, It may be tobermorite or a mixture thereof. In addition, the calcium silicate hydrate crystals obtained by conventional methods form spherical agglomerates, and the surface of the spherical agglomerates is chestnut char-shaped, and the calcium silicate hydrate is acicularly shaped. Normally, the calcium silicate hydrate crystals prepared in the present invention do not have such a shape and form spherical agglomerates with a substantially smooth surface. It is also possible to have one.

The method for preparing calcium silicate hydrate crystals (xonotlite) formed into spherical agglomerates with a special shape is basically the same as the method for producing conventional xonotlite-based molding materials. That is, a calcareous raw material and a silicic acid raw material such as silica stone are charged into an autoclave with water, and hydrothermal synthesis is carried out at a rate of 1'p per unit under conditions of clogging such that xonotlite can be produced. However, among the raw materials, as a calcareous raw material, quicklime whose size is less than the CaO crystal size (Q, 3) r is likely to be formed into the above-mentioned spherical zo/drye crystal aggregates.

However, "quicklime with a Ca○ precipitate size of 0.311 or less" refers to the average of microcrystalline grains in the form of granules or fused particles that are observed when a freshly fractured surface is observed with a scanning electron microscope. diameter (if particles are found to be fused, estimate the size of the primary particles from their shape) or 0.3
Refers to quicklime, which is microscopic and microscopic. There are no particular restrictions on the conditions for digesting the above-mentioned quicklime, and about 10
What is necessary is just to use water or hot water of 40 times the amount. As the silicic acid raw material, it is desirable to use a crystalline material, for example, a fine powder of silica stone with an average particle size of about 5 to 15 microns. These raw materials are preferably mixed in a ratio such that the Cab/5i02 molar ratio is about 0.90 to 1.10, and
Make a slurry with ~40 times the volume of water and place it in an autoclave.
Temperature 187-211°C1 Pressure 12-20 Kg/c-
Allow to react with stirring for 2 to 5 hours. After the reaction is complete,
The reaction product was gradually cooled without quenching, and the reaction product was cooled to about 100%
Take it out into the atmosphere after it cools down to below °C.

Examples of reinforcing glass fibers to be mixed with the calcium silicate hydrate crystal slurry include rock wool, slag wool, lath fibers, and ceramics. This can be achieved by using m, silica fiber, etc.

The above-mentioned reinforcing glass material 15. A slurry-like molding material is prepared by mixing fiber, calcium silicate hydrate crystal slurry, and water, and the blending ratio is preferably 5 to 150 parts by weight of calcium silicate hydrate crystals per 100 parts by weight of glass fiber. shall be 10 to 80 heavy winds. Setting the blending ratio within the above range is important in order to reduce the drying shrinkage of the dehydrated molded product and to reduce the decrease in strength of the product due to heating.

In addition, especially when there is too much fiber JU, it tends to cause defects similar to those shown by the fibrous molded body, namely, poor dimensional accuracy and insufficient normal strength.

Here, a small amount (all of the fine powder) of filler such as clay, alumina, silica, calcium carbonate, dolomite, magnesia, zirconia, perlite, wollastonite, and mica is added to improve the moldability and heat resistance of the product. up to about 30% by weight in the solid raw materials), and
In order to improve moldability and normal strength of the product, a small amount (up to about 10% by weight of the total solid raw material) of organic fibers, such as pulp and rayon fiber-8, may be blended.

In addition, the suitable amount of water for preparing the rally differs depending on the molding method, and is approximately 15 to 70 times the amount in the case of the paper making method, and approximately 10 to 30 times the amount in the case of the press molding method (in both cases, the amount of water is approximately 10 to 30 times the amount of water added to the total solid raw material). 'Ii quantitative ratio) of 5 or more are uniformly mixed to form a slurry, and then an organic polymer flocculant and a fixing agent are added. There are three types of organic polymer flocculants: anionic, 7-ionic, and cationic.
Although there are various types of flocculants, cationic ones are most suitable as the flocculants used in the present invention. Specific examples of preferable flocculants include Liei 70tsuku C-444 (Dainippon Ink and Chemicals) and San70tsuku C-009P (Sanyo Chemical).
In addition to polyacrylic 7mm I'M products, there are also polyethylene oxide based products. The round cutting has the effect of agglomerating the raw materials in the slurry, especially the powder raw materials, to improve freeness and mold releasability, and improve the moldability of the slurry. The preferred addition rate varies depending on the type of flocculant used, but is usually 01 to 1% (F), 01 to 1% (based on the total solid weight. On the other hand, if it exceeds 1%, not only the freeness deteriorates, but also the powder raw material in the slurry forms excessive coagulated water, resulting in a molded product with non-uniform density.

In addition, the agent prevents the migration of calcium silicate crystals during the process of drying the slurry after dehydration molding, and works in cooperation with the flocculant to transform the vitreous hydrate into crystals of calcium silicate hydrate. It works to make it adhere evenly to the surface. Particularly preferred fixing agents in the production method of the present invention include:
Examples include aluminum sulfate, magnesium sulfate, and magnesium chloride. The preferred addition rate is about 0.1-5% for aluminum sulfate. Addition of a large amount exceeding 5% is not preferable because not only the expected effect will be increased, but also the deterioration of the glass fibers may be accelerated.

When the slurry is gently stirred after adding the coagulant and fixing agent, it can be observed that the powder raw materials tend to coagulate and settle, so the slurry is transferred to the dehydration molding process at an appropriate stage.

The molding can be carried out by a conventional method, whether by a papermaking method or a press molding method. In addition, when using the press molding method, the press pressure is slightly lower, 0.5 to 2 Kg7'c
+o” degree: When rubbed, a hardened body is produced with calcium silicate hydrate crystal spherical lumps or a high percentage of glassy fibers with a degree of filling that is one degree lower than that of a normal calcium silicate molded body. , a molded article with low specific gravity and high strength can be obtained.

When the obtained molded product is heated and dried at about 80 to 180'C, the calcium silicate crystals are hardened mainly by alization, and the desired heat-resistant molded product is obtained.

Effects of the Invention According to the present invention, a slurry for molding is produced by blending lath fibers at a significantly higher rate than in the conventional production method of 1F bottom molding, and adding a coagulant and a fixing agent. By adding it, the freeness and mold releasability of the molding raw material are significantly improved, and it is possible to perform molding with high productivity and precision that was unimaginable in the molding of conventional calcium silicate moldings. In addition, because it is easy to mold, it has become possible to easily manufacture thick molded bodies, which was previously difficult to manufacture from calcium silicate hydrate crystal slurry. In preparing calcium silicate hydrate crystals, this becomes even more pronounced when the crystals are formed into spherical agglomerates having smooth surfaces with essentially good freeness.

In addition, there is less shrinkage in the process of drying and curing the dehydrated molded product, which not only improves the dimensional accuracy of the product, but also facilitates the design of the mold.

Furthermore, according to the present invention, the use rate of calcium silicate hydrate crystal slurry, which requires autoclave treatment, is reduced, and a hostage fiber such as inexpensive rock wool is used at a high rate instead. Therefore, it is possible to significantly increase the thermal energy consumption, which accounts for a large proportion of the manufacturing cost of conventional calcium silicate molded bodies.

Also, compared to the conventional method of obtaining a fibrous molded body by fixing the undefeated fibers with a bangu, the gaps between the a441 and the like are filled with calcium silicate crystals.
1. There are no problems with handling, and the dimensional accuracy of the product is also good.
.

According to the present invention, a high-strength, low-density, heat-resistant molded product comparable to that of conventional calcium silicate molded products can be obtained, and this molded product is particularly resistant to shrinkage and strength loss when heated to high temperatures. In that it is less likely to cause cracking or chipping,
This is superior to conventional low specific gravity heat resistant molded products.

Put the filler into a large amount of water (in some embodiments, add pulp and starch), stir well to disperse, and then add the calcium silicate crystal aquarium or laryl. - and stir. Add a fixing agent (sulfuric acid) to the resulting slurry and stir. After that, add a paracrylamide flocculant and continue stirring gently, the powder raw material will flocculate in about 30 seconds. is recognized. Therefore, the slurry concentration was adjusted to 6% (1" more, immediately 300%
Transfer to a molding frame of 300 mm x 300 + + + + o and apply pressure at a pressure rate of 10 + + + m / sec to form a plate with a thickness of 50 mm. After removing from l 5 +)
Dry at 'C for 10 hours.

Table 1 shows the results of Examples and Comparative Examples of the present invention in which the raw material formulations in the above manufacturing method were variously changed. Na s
In each example, the raw materials used were as follows.

Ceraminku (commercially available product based on aluminum 7 silicate).

Sodium/dry slurry A: Digested commercially available quicklime and ferrosilicon dust are mixed so that Ca○/SiO, = l, and placed in an autoclave with 18 times the volume of water, without stirring. The product was heated and subjected to a hydrothermal reaction under steam pressure of 15 kg and 7 cm for 5 hours.

Zonotrite slurry B: CaO crystal size n
, 2g μ of quicklime? i! 1 of this (silica powder with average diameter of 10/J) was added so that the CaO/Si○2 molar ratio was 0, and then the total amount of raw lime ash and silica powder was added. Add 30 times the amount of water to form a slurry, and heat it in an autoclave without stirring at a temperature of 197°C and a pressure of 15°C.
K4;7c+n'' for 3 hours, then li2
While continuing to cool down at a rate of 11'C/Hr,
ii) by cooling to below 10°C over a period of 7 hours.・／Nodorite needle-like ♀−
It forms a spherical monster with a smooth surface.

Tobermorite slurry: Commercially available t) 'f': Ti ash and silica powder were mixed so that Cab/5io2 = 1, placed in an autoclave with 13 F ffi water, heated with stirring, and made into 9Kg/c+a. ” obtained by hydrothermal reaction for 7 hours under steam pressure.

In addition, characteristics related to moldability such as freeness were judged based on the following criteria.

Freeness: There is no blowing out from the mold during molding, and there is no turbidity in the filtered water.
◎There is no blowing out from the formwork, and the turbidity of the filtrate is minimal.
○There is no blowing out from the formwork, but the filtrate is cloudy.
] There is a balloon from the formwork.
×Mold releasability: during molding

Claims (3)

[Claims] (1) Prepare a calcium silicate hydrate crystal slurry from a silicic acid raw material and a calcareous raw material, and mix the obtained calcium silicate hydrate crystal slurry with glass fibers and water to obtain 100 parts by weight of glass fibers. Prepare a slurry containing 5 to 150 parts by weight of calcium silicate hydrate crystals,
A heat-resistant molded product is produced by adding an organic polymer flocculant and a fixing agent to the slurry and gently stirring to agglomerate the solid raw materials, followed by dehydration molding and drying the resulting molded product. Manufacturing method. (2) The manufacturing method according to claim 1, wherein the dehydration molding is performed by cast press molding. (3) The production method according to claim 1, wherein the calcium silicate crystal hydrate forms a spherical agglomerate having a smooth surface.