JP2003073178A - Lightweight gypsum molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fibrous dihydrate gypsum crystal which can be suitably used in the form of a building material such as a heat insulating material which is lightweight, has heat insulating properties, and has excellent flame retardancy. Provided is a gypsum molded body and a method for producing the same. SOLUTION: Gypsum is heated and dissolved in hydrochloric acid, and then cooled to precipitate fibrous dihydrate gypsum, separated by filtration, and then an inorganic bond such as water glass which is alkaline and releases a gel by reaction with an acid. The aqueous solution of the agent neutralizes hydrochloric acid remaining between the fibrous dihydrate gypsums, and as a result, becomes an inorganic binding substance that is released as a gel and binds the fibrous gypsum gypsum crystals.
A lightweight gypsum molded body having a density of 0.5 g / cm ³ or less is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gypsum compact having fibrous dihydrate gypsum crystals bound thereto and a method for producing the same.
More specifically, the present invention relates to a gypsum molded body to which a fibrous dihydrate gypsum crystal having a light weight, a heat insulating property and an excellent fire resistance is bound, and a method for producing the same.

[0002]

2. Description of the Related Art Gypsum is a compound that has been used in various fields since ancient times, and especially dihydrate (dihydrate gypsum: CaSO 4
₄ · 2H ₂ O) is gypsum board, it is processed into plaster moldings gypsum building materials or the like as a main material, building material and mold material, widely used as a template material and the like. The gypsum molded body is usually prepared by dispersing powdery hemihydrate gypsum (2CaSO ₄ · H ₂ O) in water to form a gypsum slurry, and then filling it in a mold or the like and coating it on the surface of the core material to obtain a desired shape. A shaped body is obtained. For example, a gypsum board that is often used as a building material is produced in a plate shape by sandwiching it with another gypsum board base paper while flowing the gypsum slurry onto the gypsum board base paper and hydrating and solidifying.

A technique for reducing the weight of such conventional gypsum moldings has already been proposed, in which a foaming agent is added to the gypsum slurry to remove nitrogen and carbon dioxide in the gypsum molding. A method of lowering the density by including air bubbles (Japanese Patent Laid-Open No. 105544/1993, Japanese Patent Laid-Open No. 10544/1998)
No. 330174), or a method of dispersing hollow bodies of glass or resin in gypsum slurry to reduce the density (Japanese Patent Laid-Open No. 9-109317).

In addition to plaster, metal, glass, cement, stone material, inorganic fiber material, wood,
There are many materials made of wood fiber, perlite / gypsum, plastic foam, etc., and all of them are used. Among these materials, as a lightweight construction material,
Inorganic fiber materials such as glass wool, rock wool, or plastic foams such as urethane foam resin, phenolic resin foam, and styrene resin foam are available.

Since a gypsum molded body obtained from conventional hemihydrate gypsum powder has no large voids inside the molded body, the density is 2.0 to 1.5 g / cm ^{3 for} the gypsum lump and 0.9 to about for the gypsum board. 0.
It is 7 g / cm ³ . Further, even if it is a gypsum board in which air bubbles are included in order to reduce the weight, its density is 0.7 to
It is 0.6 g / cm ³ . More specifically, the standard of the commercial product is a 182 × 91 × 1.2 cm plate, and the weight is 15 to 16 kg.

Gypsum board has such a weight,
From the viewpoint of ease of handling during transportation and construction, it is desirable that the building material be lightweight, and further weight reduction of gypsum board is also desired. Further, its thermal conductivity λ is 0.
14W / (m · k), which has good heat insulation performance compared to reinforced concrete and Kyoto wall, but 3 to 4 times as much as fiber-based heat insulation materials such as glass wool and rock wool and plastic foam It is undeniable that the thermal conductivity is inferior.

However, the inorganic fiber type heat insulating material has a poor shape-retaining force, and it may not be possible to maintain the shape and heat insulating performance at the time of construction due to slipping due to its own weight or dew condensation. It is an attractive material because it is superior in heat retention compared to inorganic fiber type heat insulating materials. Further, although plastic foam has light weight and high heat insulation property, it is inferior in fire resistance to inorganic building materials even if it is flame-retardant because the main material is resin.

[0008]

As described above, gypsum board is an attractive building material and is often used, but further improvement has been desired. Then, in such a case, the present inventor eagerly carried out research with original creativity and ingenuity in order to develop a longer fibrous gypsum, and as a result, succeeded in developing a fibrous gypsum having a novel structure and already applied for a patent. (Japanese Patent Application No. 2000-145895). Regarding the developed fibrous dihydrate gypsum having a novel structure, in order to develop a utilization method in which its characteristics, particularly the shape of fibrous, can be utilized, the present invention has succeeded in earnestly conducting research. is there.

Therefore, the present invention provides a molded article such as a building material made of gypsum, such as gypsum board, which is lighter in weight, has heat insulation and is excellent in fire resistance. Is the subject of. At the same time, it is also an object of the present invention to provide a useful technique for utilizing the fibrous dihydrate gypsum having a novel structure, which the present inventor succeeded in developing. That is, the present invention is intended to provide a molded body that is lighter in weight than gypsum such as gypsum board, has heat insulating properties, and is excellent in fire resistance, and at the same time developed by the inventor. It is also an object of the present invention to provide a useful application technology of the fibrous dihydrate gypsum having a novel structure that has been successfully obtained.

[0010]

Means for Solving the Problems The means developed by the present inventor to achieve the above-mentioned object is a gypsum molded article having fibrous dihydrate gypsum crystals bound thereto and a method for producing the same, and of these, lightweight The gypsum molded article is characterized in that fibrous dihydrate gypsum crystals are bound by an inorganic binding substance and have a density of 0.5 g / cm ³ or less.

The method for manufacturing the lightweight gypsum molding is
Gypsum is heated and dissolved in hydrochloric acid, then cooled to precipitate fibrous dihydrate gypsum, filtered off, and then, with an aqueous inorganic binder solution that is alkaline and releases a gel-like substance by reaction with an acid, fibrous dihydrate Neutralize the hydrochloric acid remaining between the gypsums, and liberate by the reaction to become a gel-like inorganic binding substance,
Density for binding fibrous dihydrate gypsum crystals is 0.5 g / cm ³
It is characterized by the following.

The density of the light-weight gypsum molding of the present invention is about 40 times that of conventional gypsum moldings such as gypsum board.
It is as light as 70%. Also, the thermal conductivity is 0.05 to 0.5.
It is 08 (W / (m · k)), which is superior to the conventional inorganic molded products in heat insulation. Specifically, it is located between the gypsum board, asbestos cement perlite board, etc. and the glass fiber heat insulating board, rock wool heat insulating material, etc. in terms of density and heat insulation. In particular, the thermal conductivity, which is an index of heat insulation, is 1/2 or less as compared with the conventional gypsum board.

Further, the molded article of the present invention can be applied to refractory building materials because both the main gypsum and inorganic binding substances such as silicic acid and aluminum oxide hydrate are inorganic compounds. Is. In addition, since gypsum is a molded product that is fixed by an inorganic binding substance such as silicic acid and aluminum oxide hydrate, there is little scattering in the working environment,
Further, even when scattered, both gypsum and the inorganic binding substance have little adverse effect on the human body.

Further, from the viewpoint of handleability, since it is lightweight, workability such as transportation is good, and since the main body of the molded product is gypsum, cutting and cutting at the site are easy, and at the time of construction. Workability is also good. Moreover, since waste gypsum or various gypsum by-products can be used as the gypsum raw material, it is very effective from the viewpoint of waste treatment, waste or utilization of resources.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The present invention provides a gypsum molded product in which fibrous dihydrate gypsum crystals are bound as described above and a method for producing the same, and a building material containing the gypsum molded product, and a lightweight gypsum molded product, A fibrous dihydrate gypsum crystal is used as a main material, which is bound by an inorganic binding substance derived from an inorganic binding agent. That is, they are bound by a silicic acid component derived from water glass (sodium silicate) or an aluminum oxide hydrate derived from sodium aluminate, in which the water glass and sodium aluminate are inorganic binders, and the silicic acid component and aluminum oxide are Hydrates are inorganic binding substances.

The fibrous dihydrate gypsum crystal, which is the main raw material for producing the gypsum molded product, preferably has a length of 0.05 to 10 mm and a diameter of 1 to 200 μm, but is not limited thereto. Any material can be used without limitation as long as it can be made to have a density of 0.5 g / cm ³ or less after being bound by the inorganic binding substance. As a method for producing the fibrous gypsum, Japanese Patent Application No. 2 developed by the present inventor
The method described in 000-145895 is preferable, and the manufacturing method is as follows.

That is, it is obtained by heating and dissolving gypsum in hydrochloric acid, and then cooling to precipitate fibrous dihydrate gypsum and separate it by filtration. As a raw material for the fibrous dihydrate gypsum, it is preferable to use gypsum powder, which includes natural gypsum, synthetic gypsum, by-product gypsum during phosphoric acid refining, exhaust de-gypsum by-product of flue gas desulfurization, etc. Various gypsum powders can be used without any particular limitation. There is no limitation on the type of gypsum used as described above, but it is desirable to use by-product gypsum or waste gypsum when phosphoric acid is generated in order to effectively use resources. In particular, these by-product gypsums are currently over-produced, and their proper disposal is a problem, and their effective use is significant.

The water content of gypsum at that time is not limited to gypsum dihydrate, but may be hemihydrate gypsum or anhydrous gypsum. This is because the production of the fibrous dihydrate gypsum, which is the raw material of the present invention, is based on a crystallization operation in which gypsum is once dissolved and then cooled to precipitate. That is, if the gypsum can be dissolved in hydrochloric acid, gypsum dihydrate will be deposited at the time of deposition after dissolution.

The concentration of hydrochloric acid used for dissolving the raw gypsum powder is preferably 2 mol / l or more and less than 6 mol / l, and more preferably 3 mol / l or more and less than 5 mol / l. In the dissolution of gypsum with this hydrochloric acid, it is preferable to dissolve the entire amount of gypsum from the viewpoint of production efficiency, improvement of purity, and homogenization of fiber shape, but it may remain partially undissolved. In that case, the same effect as in the case where the entire amount is dissolved can be obtained by separating the undissolved gypsum powder and the solution and using only the solution for the crystallization operation. After dissolution as described above, a gypsum-dissolved hydrochloric acid solution or hydrochloric acid slurry (hereinafter sometimes abbreviated as a hydrochloric acid solution or the like) is formed.

It is preferable that the concentration of hydrochloric acid be within the above range, if the amount is less than 2 mol / l, the solubility of calcium sulfate during heating is low and the amount of fibrous dihydrate gypsum deposited during cooling is small. Manufacturing efficiency is low. On the contrary, when the concentration of hydrochloric acid exceeds 6 mol / l, the solubility of gypsum after cooling is high, and fibrous gypsum cannot be efficiently obtained. In addition, the amount of hydrogen chloride volatilized from the gypsum-hydrochloric acid slurry during heating increases, promoting corrosion and deterioration of surrounding metal products,
It is not preferable because it deteriorates the surrounding work environment.

To dissolve gypsum powder in hydrochloric acid, gypsum powder is poured into hydrochloric acid at room temperature to sufficiently disperse it, and then the mixture is heated to a predetermined temperature with stirring and maintained at a predetermined temperature for a certain time after reaching the predetermined temperature. And dissolve. Alternatively, various methods such as dissolving gypsum powder in hydrochloric acid by heating the hydrochloric acid to a predetermined temperature in advance and adding the gypsum powder to the mixture while maintaining the predetermined temperature while stirring for a certain period of time are not particularly limited. Can be adopted. The heating temperature for dissolving the raw material gypsum powder is preferably 60 ° C or higher and lower than 105 ° C, and preferably 80 ° C or higher and lower than 100 ° C.

The reason for this is that if the heating temperature is lower than 60 ° C., the difference in solubility of calcium sulfate in hydrochloric acid during heating and cooling is small, and the synthetic efficiency of fibrous dihydrate gypsum becomes low. On the other hand, if the temperature exceeds 105 ° C, the amount of hydrogen chloride volatilized from a hydrochloric acid solution in which gypsum is dissolved increases, which promotes corrosion and deterioration of surrounding metal products and causes deterioration of the surrounding work environment, which is not preferable. In addition, there is a risk that hydrochloric acid will be scattered due to boiling of the hydrochloric acid solution or the like.

The cooling of the hydrochloric acid solution in which gypsum is dissolved is preferably performed at a cooling rate of 0.5 ° C./min or more and 3 ° C./min or less, and preferably 0.8 ° C. or more and 1.5 ° C./min or less. Is good.
The reason is that when the cooling rate of the hydrochloric acid solution or the like is less than 0.5 ° C./min, the fiber length of the fibrous gypsum is not longer than that when the cooling rate is about 0.5 to 1 ° C./min. The precipitation amount of the gypsum dihydrate gypsum crystals depends on the temperature difference and does not depend on the cooling rate. Therefore, it takes more time than necessary to grow the fibrous dihydrate gypsum crystals, because the production efficiency deteriorates. Further, when the cooling rate exceeds 3 ° C./min, the precipitation rate of the crystals becomes too fast, and the fine fibrous crystals or powdery crystals mostly form, making it difficult to achieve the purpose of obtaining fibrous dihydrate gypsum. .

When the fibrous dihydrate gypsum is deposited,
When the hydrochloric acid solution is left standing without stirring, the length is 0.2 to 10 m.
m, a long fibrous dihydrate gypsum crystal having a diameter distributed in the range of 1 to 200 μm is obtained, and short fibrous dihydrate distributed in the range of 0.05 to 1 mm when the stirring is continued and the hydrochloric acid solution is kept in a fluid state. Gypsum crystals are obtained. Therefore, when producing a lightweight gypsum molded body mainly composed of long fibers, a hydrochloric acid solution in which gypsum is dissolved is allowed to stand, and when a lightweight gypsum molded body mainly composed of short fibers is manufactured, gypsum-dissolved hydrochloric acid is dissolved. By stirring the solution, it is possible to change the properties of the fibrous gypsum dihydrate crystals that form the lightweight gypsum compact.

The cooling end temperature of the hydrochloric acid solution in which gypsum is dissolved is preferably 0 to 30 ° C, preferably 0 to 20 ° C.
If the cooling end temperature exceeds 30 ° C., the gypsum solubility of hydrochloric acid is still high, and a large amount of gypsum remains in the hydrochloric acid, and a fibrous dihydrate gypsum cannot be efficiently obtained. In addition, when the hydrochloric acid solution is further cooled, the remaining gypsum precipitates as fibrous dihydrate gypsum crystals, and additional work such as removal of hydrochloric acid during reuse is added, which hinders efficient work.

Separation of the precipitated fibrous dihydrate gypsum crystals from the hydrochloric acid solution is not particularly limited and can be carried out by various solid-liquid separation operations such as filtration or centrifugation.
If a separating means that applies an excessive force to the fibrous dihydrate gypsum is used, the fibers will be cut, so the force that is applied during separation will be small, and the solid-liquid separation efficiency will be high. It is preferable to employ solid-liquid separation means such as a vacuum vacuum filter or a vertical disk vacuum filter.

The fibrous dihydrate gypsum after the solid-liquid separation contains hydrochloric acid remaining between the fibers, and the fibrous dihydrate gypsum after separation neutralizes the residual hydrochloric acid and at the same time develops a binding force. Except when a particularly desirable inorganic binder such as glass is used, it is desirable to wash away residual hydrochloric acid that inhibits binding. Even when an inorganic binder such as water glass having the ability to neutralize the residual hydrochloric acid is used, a part of the hydrochloric acid may be washed and removed when the residual hydrochloric acid is likely to be excessive.

For removing the hydrochloric acid, an organic solvent such as lower alkyl alcohol compatible with hydrochloric acid can be used. Specific organic solvents that can be used for washing include lower alkyl alcohols such as methanol, ethanol, propanol and butanol, lower alkyl ethers such as dimethyl ether and methyl ethyl ether, and lower alkyl ketones such as acetone and methyl ethyl ketone.

The inorganic binder used in the present invention has the ability to neutralize residual hydrochloric acid as described above and at the same time to produce a solid, and the produced solid has an ability to develop a binding force (referred to as an inorganic binding substance). Preferred examples thereof include sodium aluminate and the like in addition to the above-mentioned water glass, but the preferable inorganic binders are not limited to these two, and any one having similar performance can be used.

As described above, it is preferable that the above-mentioned inorganic binder has both the ability to neutralize residual hydrochloric acid and the ability to bind gypsum, but the neutralizing ability is not essential. Instead, any material having the ability to bind fibrous dihydrate gypsum may be used. Further, when an inorganic binder such as water glass having a neutralizing ability is used and the residual amount of hydrochloric acid becomes excessive, an alkaline solution such as caustic soda may be used for neutralization. When hydrochloric acid is insufficient due to excessive washing, hydrochloric acid may be replenished and used.

In order to develop the binding performance of the inorganic binder, it is essential that the binder is present on the surface of the fibrous dihydrate gypsum. Any material can be used as long as it can spread the binder on the surface of gypsum dihydrate, for example, a method of impregnating it by spraying a binder solution, a method of immersing a fibrous dihydrate gypsum lump in the binder solution for impregnation. Alternatively, a method in which a fibrous hydrated gypsum lump is defibrated and the surplus liquid is filtered after being dispersed in a binder liquid can be exemplified. In addition, it is not preferable that the fibrous dihydrate gypsum is applied with a strong dipping force, and as a result, the fibrous dihydrate gypsum is cut and the fibrous form disappears.

In the present invention, the water glass used as a preferred inorganic binder is also called sodium silicate,
Formula is represented by _{Na 2 O · nSiO 2 · mH} 2 O, for industrial liquid products (n = 2 to 4) is mainly produced and used. The water glass is industrially manufactured as described above, and according to JISK1408, No. 1 (n = 1.9-
2.3), No. 2 (n = 2.3 to 2.7), No. 3 (n = 2.9)
~ 3.4). In the present invention, these water glasses can be used without particular limitation.

As described above, the aqueous solution of these water glasses exhibits alkalinity and has a pH buffering action against acid. Further, sol-like or gel-like silicic acid is released by adding a slight excess of acid. In the present invention, this water glass is contacted with hydrochloric acid to release silicic acid, which is referred to as an inorganic binding substance in the present invention, and the released silicic acid fixes fibrous dihydrate gypsum crystals to one another to form fibrous dihydrate gypsum. It maintains the shape of the body.

Similarly, sodium aluminate, which is also a preferable inorganic binder, is obtained by adding aluminum hydroxide to an aqueous solution of sodium hydroxide and heating it, which is soluble in water and the pH of the aqueous solution is 12.3. Shows the alkalinity of. When an acid such as hydrochloric acid is added to an aqueous solution of sodium aluminate, the hydrochloric acid is neutralized and at the same time, a gelled aluminum oxide hydrate is released. The liberated aluminum oxide hydrate is an inorganic binding substance, which fixes the fibrous dihydrate gypsum crystals to each other and maintains the shape of the fibrous dihydrate gypsum compact as in the case of water glass.

Next, the method for producing the lightweight gypsum molded product of the present invention will be described again in detail. That is, the fibrous dihydrate gypsum obtained by the method for producing the fibrous dihydrate gypsum is separated from hydrochloric acid by filtration. , The residual hydrochloric acid is neutralized with water glass or an inorganic binder such as sodium aluminate where the aqueous solution is alkaline, and at the same time, the silicic acid content released from the water glass by the reaction with the acid or the alumina gel released from sodium aluminate A gypsum molded body having a density of 0.5 g / cm ³ or less is produced by binding with an inorganic binding substance which is a gel-like substance.

The light-weight gypsum molded product of the present invention is typically obtained as described above. Since it mainly contains fibrous gypsum, it contains many voids inside the molded product, and as a result, It is lightweight and has excellent heat insulation performance. In particular, its thermal conductivity is equivalent to that of an inorganic fiber material-based mat-like or board-like heat insulating material, and the same heat insulating performance is exhibited.

Therefore, the lightweight gypsum molding of the present invention can be used as a building material to produce a building material which is lighter in weight and higher in heat insulation than conventional inorganic building materials. Specific examples of the building material include a heat insulating material, an interior wall material, a ceiling material, a floor material, and a pipe coating material.
As a molding means for forming these forms, a conventional method that has been used conventionally can be adopted.

The composition is composed of gypsum (calcium sulfate dihydrate) and an inorganic binding substance such as silicic acid (silicon dioxide) or aluminum oxide hydrate.
Both are made of inorganic materials only and can be used as fireproof building materials. In addition, when strength is required like a floor material, a desired performance can be achieved by laminating a protective layer material on the front surface and a reinforcing material on the back surface.

Further, the lightweight gypsum molded product of the present invention is one in which fibrous dihydrate gypsum crystals are bound by an inorganic binding substance, but it is not necessary to consist of both of them, and they are bound by an inorganic binding substance. It is mainly composed of fibrous gypsum dihydrate crystals, and may contain other components as long as its characteristics, specifically, density, heat insulation, fire resistance and the like are not impaired. Examples of such components include gypsum powder, bentonite, wollastonite, and the like.

[0040]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. It goes without saying that the present invention is not limited by this embodiment but is specified by the scope of the claims.

[Example 1] 45 g of calcium sulfate dihydrate (hereinafter referred to as gypsum plaster) by-produced by flue gas desulfurization had a concentration of 5 mol.
The mixture was dispersed in 2 liters of hydrochloric acid / liter, and the mixture was heated and stirred at 95 ° C for 15 minutes while stirring. Subsequently, heating was continued, stirring was stopped, undissolved impurities and undissolved gypsum (hereinafter simply referred to as undissolved components) were allowed to settle, and the supernatant was transferred to another container to separate undissolved components. After that, the hydrochloric acid solution in which the waste gypsum is dissolved is statically cooled at a cooling rate of 1 ° C / min for 25 hours.
The mixture was cooled to ° C, and fibrous crystals of calcium sulfate dihydrate were precipitated in the liquid.

Next, the precipitated fibrous crystals of calcium sulfate dihydrate were filtered from the hydrochloric acid solution using a Buchner funnel and filter paper. Concentration of solid content in another container after filtration 54
An aqueous solution of 20% by weight of No. 1 water glass dissolved in 270 g of water is sprinkled and impregnated on a fibrous crystal mass of calcium sulfate dihydrate containing hydrochloric acid between fibers on a Buchner funnel,
The hydrochloric acid was neutralized and the silicic acid content was released. At that time, the alkaline component which was insufficient for neutralizing the hydrochloric acid was supplemented by appropriately spraying a 0.1 mol / l sodium hydroxide aqueous solution.

Confirmation of the completion of the neutralization reaction is carried out by pH test paper.
The application of the mol / l sodium hydroxide aqueous solution was stopped. From the slurry of calcium sulfate dihydrate fibrous crystals after neutralization of hydrochloric acid and liberation of silicic acid content, the fibrous crystals of calcium sulfate dihydrate and the solution were filtered using a Buchner funnel and filter paper to obtain fibrous gypsum. Got a lump of. The obtained fibrous gypsum lump was dried by a dryer at 95 ° C. to obtain a lightweight gypsum molded body.

[Example 2] 45 g of waste gypsum was added at a concentration of 5 mol /
It was dispersed in 1 liter of hydrochloric acid (2 liter) and stirred for 15 minutes while heating and maintaining at 95 ° C. Subsequently, the heating was continued, the stirring was stopped, the undissolved components were allowed to settle, and only the supernatant liquid was transferred to another container and separated from the undissolved components. After that, the peripheral speed is 0.9-1
While stirring at a speed of m / sec, the hydrochloric acid solution in which the discharged gypsum is dissolved is cooled to 25 ° C at a cooling rate of 1 ° C / min / min, and the fibrous crystals of calcium sulfate dihydrate are liquefied. Deposited inside. The precipitated fibrous crystals of calcium sulfate dihydrate were filtered from the hydrochloric acid solution using a Buchner funnel and filter paper.

Then, the solid content concentration of 39 was prepared in a separate container.
A fibrous crystal of calcium sulfate dihydrate containing hydrochloric acid was dispersed between the fibers in an aqueous solution prepared by dissolving 40 g of No. 3 water glass in an amount of 160 ml of water to neutralize the hydrochloric acid and release the silicic acid content. . From the slurry of calcium sulfate dihydrate fibrous crystals after neutralization of hydrochloric acid and liberation of silicic acid content, the fibrous crystals of calcium sulfate dihydrate and the solution were filtered using a Buchner funnel and filter paper to obtain fibrous gypsum. Got a lump of. The obtained fibrous gypsum lump was dried by a dryer at 95 ° C. to obtain a lightweight gypsum molded body.

Example 3 In the same manner as in Example 2, fibrous crystals of calcium sulfate dihydrate were precipitated in the liquid. The precipitated fibrous crystals of calcium sulfate dihydrate were filtered from the hydrochloric acid solution using a Buchner funnel and filter paper. After separating by filtration, 25 g of sodium aluminate powder prepared in another container is mixed with 3 parts of water.
Fibrous crystals of calcium sulfate dihydrate containing hydrochloric acid between the fibers were dispersed in an aqueous solution dissolved in 00 ml to neutralize the hydrochloric acid and release the aluminum oxide hydrate.

Fibrous crystals of calcium sulfate dihydrate and the solution were filtered using a Buchner funnel and filter paper from the slurry of calcium sulfate dihydrate fibrous crystals after neutralization of hydrochloric acid and release of aluminum oxide hydrate was completed. Separated, a lump of fibrous gypsum was obtained. The obtained fibrous gypsum lump was dried by a dryer at 95 ° C. to obtain a lightweight gypsum molded body.

[Example 4] By the same method as in Example 2, fibrous crystals of calcium sulfate dihydrate were precipitated in the liquid. The precipitated fibrous crystals of calcium sulfate dihydrate were filtered from the hydrochloric acid solution using a Buchner funnel and filter paper. After separation by filtration, fibrous crystals of calcium sulfate dihydrate containing hydrochloric acid between the fibers were dispersed in 300 ml of an aqueous solution of sodium aluminate having a solid content concentration of 8% by weight, which was prepared in another container to neutralize the hydrochloric acid and aluminum oxide. The hydrate release operation was performed.

Fibrous crystals of calcium sulfate dihydrate and the solution were filtered using a Buchner funnel and filter paper from the slurry of calcium sulfate dihydrate fibrous crystals after neutralization of hydrochloric acid and release of aluminum oxide hydrate was completed. Separated, a lump of fibrous gypsum was obtained. The obtained fibrous gypsum lump was dried by a dryer at 95 ° C. to obtain a lightweight gypsum molded body.

Example 5 In the same manner as in Example 2, fibrous crystals of calcium sulfate dihydrate were precipitated in the liquid. The precipitated fibrous crystals of calcium sulfate dihydrate were filtered from the hydrochloric acid solution using a Buchner funnel and filter paper. After separation by filtration, 250 ml of an aqueous solution of sodium aluminate having a solid content concentration of 10% by weight prepared in another container is sprinkled and permeated into the fibrous crystals of calcium sulfate dihydrate containing hydrochloric acid between the fibers to neutralize the hydrochloric acid. The release operation of the aluminum oxide hydrate was performed.

Fibrous crystals of calcium sulfate dihydrate and the solution were filtered using a Buchner funnel and filter paper from the slurry of calcium sulfate dihydrate fibrous crystals after neutralization of hydrochloric acid and release of aluminum oxide hydrate was completed. Separated, a lump of fibrous gypsum was obtained. The obtained fibrous gypsum lump was dried by a dryer at 95 ° C. to obtain a lightweight gypsum molded body.

[Measurement of Density and Thermal Conductivity] With respect to the lightweight gypsum moldings produced in each example, the density and thermal conductivity were measured. The density was determined by dividing the weight (g) of the molded product by the volume (cm ³ ) determined from the outer dimensions of the molded gypsum product manufactured in each example. The thermal conductivity is determined by the heat flow method [JISR
2618], the values at 0, 20, and 60 ° C. were measured.

The measurement results of the density and the thermal conductivity of each example are shown in Table 1. These measurement results show that the lightweight gypsum molding of the present invention has a smaller density and a lower thermal conductivity than inorganic building materials such as gypsum board and concrete. In particular, regarding the thermal characteristics, there is between the inorganic building materials such as gypsum board and the inorganic fiber building materials such as glass fiber board,
It is similar to inorganic fiber-based building materials such as glass fiber boards. In Table 1, the density and thermal conductivity of typical inorganic building materials are also shown as a reference example. The numerical value of the reference example written together is
The description is quoted in "Technical Data on Thermal Insulation and Dew Condensation for Buildings" issued by Information Development Co., Ltd.

[0054]

[Table 1]

[0055]

EFFECTS OF THE INVENTION The lightweight gypsum molding of the present invention has a density as low as 40 to 70% of that of a gypsum molding such as a gypsum board produced by a conventional manufacturing method. Also, the thermal conductivity is 0.0
It is 5 to 0.08 (W / (m · k)), and is superior in heat insulation property to various conventional inorganic molded products. In terms of its light weight and heat insulating properties, it is positioned between a gypsum board, asbestos cement perlite board and the like and a glass fiber heat insulating board, rock wool heat insulating material and the like. Further, the composition components thereof are gypsum and an inorganic binding substance such as silicic acid or aluminum oxide hydrate, and can be used as a form of a fire resistant building material.

From the viewpoint of handleability, the workability such as transportation is good because it is lightweight. Further, since the main material is gypsum, cutting and cutting at the site is easy and workability during construction is good. Furthermore, since the fibrous gypsum is a molded product that is solidified with an inorganic binding substance, the gypsum fibers are less likely to be scattered into the working environment. Moreover, since waste gypsum or various gypsum by-products can be used as the raw material, it is very effective from the viewpoint of resource utilization or waste treatment or utilization.

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Claims (7)

[Claims] 1. A lightweight gypsum molded product characterized in that fibrous dihydrate gypsum crystals are bound by an inorganic binding substance and have a density of 0.5 g / cm ³ or less. 2. The lightweight gypsum molded product according to claim 1, wherein the fibrous dihydrate gypsum is obtained by dissolving gypsum in hydrochloric acid by heating and then precipitation by cooling. 3. The lightweight gypsum molded product according to claim 1, wherein the inorganic binding substance is a gel-like substance that is liberated by a reaction with an acid. 4. The lightweight gypsum molding according to claim 1, wherein the inorganic binding substance is silicic acid or aluminum oxide hydrate liberated by a reaction with an acid. 5. A heat insulating material, a wall material for interior, a partition material,
The lightweight gypsum molded product according to claim 1, which is a building material such as a ceiling material, a floor material, a pipe coating material or a structural material coating material. 6. An aqueous solution of an inorganic binder which dissolves gypsum in hydrochloric acid by heating, and then cools to precipitate fibrous dihydrate gypsum, separates by filtration, and is alkaline and liberates a gel by reaction with an acid. , Neutralizes the residual hydrochloric acid between the fibrous dihydrate gypsum, and is liberated by the reaction to become a gel-like inorganic binding substance, and the density for binding the fibrous dihydrate gypsum crystals is 0.5 g / cm ³ The following is a method for producing a lightweight gypsum molding. 7. The method for producing a lightweight gypsum molded body according to claim 6, wherein the inorganic binder is sodium silicate or sodium aluminate.