JPS62113747A - Manufacture of calcium silicate formed 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 Technical Field The present invention relates to a method for producing a calcium silicate molded body with significantly improved heat insulation performance.

1. The calcium silicate molded body is lightweight. It is widely used in various fields due to its excellent heat insulation properties, high fire resistance, and many other properties.

In recent years, in the fields of heat retaining materials, heat insulating materials, etc., there has been a demand for calcium silicate molded bodies with even higher heat insulation performance.

JP-A-58-145652 discloses a method of improving the heat insulating properties by incorporating a substance that absorbs or scatters radiant energy into a calcium silicate molded body. However, in this method, if the content of the above substance exceeds 20% by weight in the molded article, the thermal conductivity increases, and furthermore,
There is a limit that the thermal conductivity can be lowered only by silicon carbide, silicon nitride, and ilmenite when the content is less than 0% by weight or less.

DISCLOSURE OF THE INVENTION The present invention overcomes the limitations of the conventional methods described above.
The purpose is to provide a method for manufacturing a calcium silicate molded body with significantly improved heat insulation performance.

In the present invention, an aqueous slurry of a calcium silicate crystal precursor is prepared by preliminarily reacting a raw material slurry containing a silicate raw material, a lime raw material, and water while heating and stirring under normal pressure or pressure, and then molding the slurry. In the method of manufacturing a calcium silicate molded body by steam curing and drying the formed body obtained by steam curing, the infrared shielding material is added to the raw material slurry or the aqueous slurry of the calcium silicate crystal precursor, and dry heat curing is performed instead of steam curing. The present invention relates to a method for producing a calcium silicate molded body.

The calcium silicate molded body obtained by the method of the present invention has significantly improved heat insulation performance due to the inclusion of an infrared shielding material, and also maintains sufficient strength for practical use.

According to the method of the present invention, the content and type of infrared shielding material are not substantially limited. That is, any infrared shielding material can be used to improve the heat insulation performance, and in particular, when the shielding material is contained in an amount exceeding 20% by weight in the total solid content of the molded article, the heat insulation performance is further significantly improved. In addition, conventional steam curing of formed bodies has the disadvantage that the formed bodies may undergo shrinkage, deformation, cracks, etc. (this disadvantage usually increases as the amount of additives increases); According to the method of the invention, this drawback can be overcome despite the inclusion of an infrared shielding material.

The reason why the above-mentioned effects can be obtained by the present invention is not clear, but the stress strain on the calcium silicate precursor due to the residual stress strain caused by molding in the formed body and the infrared shielding material contained in the formed body is It can be assumed that deformation of the molded article can be prevented because the effect can be alleviated by performing dry heat curing instead of steam curing.

The infrared shielding material used in the present invention refers to a compound that has the property of shielding infrared rays, which are heat rays, and is chemically inactive with respect to the formation reaction of calcium silicate crystals.
Preferred specific examples include activated carbon, charcoal, coal,
Carbon substances such as carbon black and graphite, carbides such as silicon carbide, boron carbide, and titanium carbide, nitrides such as silicon nitride, boron nitride, and titanium nitride, silicides such as calcium silicide, iron oxides (hematite, magnetite, etc.), Titanium oxide (rutile, anatase, etc.), tin oxide, manganese oxide, zirconium oxide, ilmenite, zircon, celium oxide,
Examples include metal oxides such as lanthanum oxide, WA elemental oxide, and chromite. In the present invention, one kind or a mixture of two or more kinds of infrared shielding materials can be used.

Among these, particularly preferred infrared shielding materials include graphite, silicon carbide, titanium carbide, boron nitride, iron oxide, titanium oxide,
These include tin oxide, manganese oxide, zirconium oxide, ilmenite, cerium oxide, and lanthanum oxide.

In the present invention, 1q of formed bodies formed by molding an aqueous slurry of calcium silicate crystal precursors are subjected to dry heat curing. Dry heat curing in the present invention is usually carried out in a pressure-resistant closed container such as an autoclave by heating the container to a temperature of about 130 to 300° C. without blowing in steam. The dry heat curing time usually varies from 3 to 30 hours. The heating temperature and time for dry heat curing are as follows:
Types of calcium silicate crystal precursors constituting the formed form,
It is appropriately determined within the above range depending on the type of calcium silicate crystals to be obtained, the shape and size of the molded article, etc.

Through the above-mentioned dry heat curing, water vapor is generated from the formed body, and the silicate lucium crystal precursor in the formed form is converted into calcium silicate crystals such as tobermolite crystals, xonotrite crystals, and fociagite crystals by this water vapor and heat. .

This dry heat curing not only prevents deformation of the molded product, but also improves the strength and dimensional stability compared to the case without this treatment.

The manufacturing method of the present invention is basically the same as that disclosed in Japanese Patent Publication No. 41-1953, except that an infrared fast-acting material is added to the raw material slurry or an aqueous slurry of calcium silicate crystal precursor, and dry heat curing is performed instead of steam curing. Or Tokuko Sho 58-30
A raw material slurry containing a silicic acid raw material, a lime raw material, and water as described in 259@ is preliminarily reacted with stirring under normal pressure or pressure to prepare an aqueous slurry of a calcium silicate crystal precursor, and then this is molded. The method is similar to that of producing a calcium silicate molded body by steam curing and drying the resulting molded body.

As the silicic acid raw material used in the present invention, any of those conventionally used in the production of calcium silicate molded bodies can be effectively used.
In addition, silica gel and silica flower (
Examples include ferrosilicon dust, etc.), white carbon, diatomaceous earth, and silica obtained by reacting hydrosilicofluoric acid and aluminum hydroxide, which are by-produced in the wet phosphoric acid manufacturing process. Furthermore, any lime raw material that has been used conventionally can be used, and examples include quicklime, slaked lime, and carbide slag.

Further, the CaO/SiO2 molar ratio of the silicic acid raw material and the lime raw material is usually about 0.5 to 1.5. For example, when trying to synthesize tobermolite crystal, it is about 0.70-0.90, and when trying to synthesize xonotlite crystal, it is about 0.9
It is preferably about 0 to 1.15, and preferably about 1.1 to 1.5 when synthesizing a fociagite crystal.

In the production method of the present invention, a raw material slurry is prepared by adding the above-mentioned silicic acid raw material, lime raw material, and water, or further adding an infrared fastening material to these.

Conventionally known additives may be added to the raw material slurry, and examples of such additives include inorganic fibers such as asbestos and rock wool. The amount of water when preparing the raw material slurry is 5 times or more by weight, preferably 10 to 50 times the solid content of the raw material slurry.

Next, this raw material step 1 is preliminarily reacted to prepare an aqueous slurry of a calcium silicate solid precursor. Calcium silicate crystal precursors refer to various intermediates when calcium silicate crystals are generated from silicic acid raw materials and lime raw materials,
For example, calcium silicate gel, C-3-H(n), C-3
-H(I>, etc.).The method for obtaining the precursor is, for example, adding about 80 to 98% of the raw material slurry under normal pressure.
Avoid the reaction by heating to °C, or usually 3 K'J/
This is carried out by carrying out a hydrothermal synthesis reaction under a saturated steam pressure of at least cm. This provides an aqueous slurry of calcium silicate crystal precursor.

When the infrared fast material is not added to the raw material slurry, the infrared fast material is added to the aqueous slurry of the precursor and mixed uniformly.

In the present invention, it is appropriate that the amount of the infrared ray fastening material added is such that the content in the molded product is approximately 1 to 70% by weight, preferably approximately 10 to 60% by weight based on the total solid content of the molded product. It is. If the amount added is within this range, the heat insulation performance can be significantly improved by 1q while maintaining sufficient practical strength.

The infrared ray fastening material used is usually in the form of powder, and its particle size is usually about 0.01 to 150 μm, preferably about 0.001 to 100 μm.

Furthermore, as the above-mentioned infrared ray fast material, both synthetic and natural materials can be used, and although these may contain impurities, they may be used as long as they do not have any adverse effects.

Next, the aqueous slurry of the calcium silicate crystal precursor containing the infrared fast material obtained above is molded. At this time, prior to molding, various additives may be further added and mixed as necessary. As additives in this case, a wide range of materials that have been used in the production of calcium silicate molded bodies can be used, and examples include fibers and the like. The molding method may be, for example, press dehydration molding, centrifugal dehydration molding, roll dehydration molding, mold molding, paper forming, extrusion molding, or the like.

Next, the green body obtained above is subjected to dry heat curing as described above. Next, the desired calcium silicate molded body is obtained by drying.

In addition, during molding, if necessary, an aqueous slurry of calcium silicate crystal precursor containing an infrared fastening material and the slurry not containing an infrared fastening material are used, for example, by placing the former slurry in a mold. A laminate molded product can also be obtained by performing press dehydration molding, and then placing the latter slurry in a mold and performing press dehydration molding, or by performing the reverse operation.

The calcium silicate molded article provided by the present invention can be easily manufactured from high density to low density,
In particular, even a molded article having a low density and a light weight, for example a high density of about 0.1 g/cm3, can be easily produced.

EXAMPLES The present invention will be specifically explained below with reference to Examples. However, parts and percentages in the following examples indicate parts by weight and percentages by weight, respectively, and various physical properties were measured by methods such as those described in the following methods.

(a) Bending strength: Measured according to the method of JIS A9510.

(b) Thermal conductivity: Measured according to the cylinder method of JIS A9510.

Example 1 Quicklime (94.8% CaO) was slaked in warm water at 80°C and dispersed in water using a homomixer to obtain milk of lime. Silica stone powder (SiO2 with an average particle size of 4.6 μm) is added to the above lime milk.
97.6%) Cab/S! 02 molar ratio is 1.00
In addition, add water or a predetermined amount of titanium oxide (rutile, average particle size 2.0 μm) as an infrared fast material.
) Powder and water were added and mixed so that the total amount of water was 24 times the weight of the solid content to obtain a raw material slurry. This was stirred in an autoclave at a saturated steam pressure of 14 KFi/ctrl and a temperature of 197°C with a stirring rack rotating at a rotation speed of 4 Or, oom, and reacted for 2 hours.
An aqueous slurry containing C-1(1) or C-3-H(I> and rutile crystals as main components) was obtained.

Next, 5 parts of alkali-resistant glass fiber and 3 parts of pulp were added to 92 parts (solid content) of the slurry obtained above, and press dehydration molding was performed to form a cylindrical product with an inner diameter of 114 mm, a thickness of 50 mm, and a length of 610 mm. I got it. This formed body was placed in an indirect heating autoclave and dry heat cured at 180° C. for 8 hours. After natural curing, this molded body was dried at 100°C.

It should be noted that during natural curing, the molded product did not experience any shrinkage, deformation, cracks, etc.

When the obtained compact was analyzed by X-ray diffraction, peaks of xonotrite crystals and rutile crystals were observed in the case of the product to which titanium oxide powder was added.

The physical properties of each molded article were as shown in Table 1.

From Table 1, it is clear that the molded bodies obtained by the method of the present invention all have significantly improved heat insulation performance and also maintain sufficient practical strength.

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Claims (2)

[Claims] (1) A raw material slurry containing a silicate raw material, a lime raw material, and water is preliminarily reacted with stirring under normal pressure or pressure to prepare an aqueous slurry of a calcium silicate crystal precursor, and then this is molded. In the method of manufacturing a calcium silicate molded body by steam curing and drying the resulting formed body, an infrared shielding material is added to the raw material slurry or an aqueous slurry of a calcium silicate crystal precursor, and dry heat curing is performed instead of steam curing. A method for producing a calcium silicate molded body, characterized by: (2) The infrared shielding material is carbon material, carbide, nitride,
The manufacturing method according to claim 1, wherein the material is at least one of a silicide and a metal oxide.