JPS6143315B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a molded body. As a method for producing a lightweight molded body, a method has recently been proposed in which a molded body is obtained by hydration-curing using a fibrous bodywork or a spherical body formed substantially from a fibrous bodywood as a raw material. The raw material used in these methods is usually an aqueous slurry of α-type hemihydrate obtained by hydrothermally reacting an aqueous slurry mainly composed of dihydrate at 100 to 180°C. This α-type hemihydrate is stable at temperatures above about 80°C, but when the temperature drops, it converts to dihydrate. In order to prevent this conversion to dihydrate, an aqueous slurry of α-type hemihydrate is heated, washed with alcohol if necessary, and dried to obtain α-type hemihydrate. A method of mixing and molding is adopted. However, since this method requires complicated steps, it is desired to directly mold the hydrothermal reaction slurry. However, the method of directly molding a hydrothermal reaction slurry has the disadvantage that the strength of the molded product obtained is extremely low compared to molded products produced by conventional methods. The object of the present invention is to eliminate the above-mentioned drawbacks and provide a method for producing a molded article with high strength through a simplified process, even though it is directly molded from a hydrothermal reaction slurry. The present invention provides an aqueous slurry made of dihydrate, hemihydrate, soluble anhydrous or a mixture thereof, and formed from α-type hemihydrate fibrous and/or substantially fibrous slurry at a temperature of 100 to 180°C. A hydrothermal reaction is carried out until a spherical shell is obtained, and at least one of a β-type hemihydrous shell, a soluble anhydrous shell, and an aqueous solution of the shell is added to the aqueous slurry of the obtained reaction product, and then dehydrated and shaped. The present invention provides a method for producing a molded body that is characterized by being hardened. In the present invention, the slag used as a raw material is dihydrated sludge, semi-hydrated sludge, soluble anhydrous sludge, or a mixture thereof.Those containing these as main ingredients include naturally occurring sludge, chemically synthesized sludge, and excreted sludge. etc. Any one is fine. An appropriate amount of the above raw material is mixed with water to form an aqueous slurry. Usually, this aqueous slurry is used, but if necessary, a small amount of an acid, a water-soluble organic substance, or both may be appropriately added to the water. The acids used here include organic acids,
Any inorganic acid may be used, such as acetic acid, tartaric acid,
Organic acids such as formic acid and malic acid, hydrochloric acid, sulfuric acid, nitric acid,
Inorganic acids such as boric acid are preferred. There are no particular restrictions on the amount of these acids added, but the concentration in the aqueous solution is usually 0.05 to 10% by weight for organic acids, preferably 0.1 to 5% by weight, and 0.01% for inorganic acids.
-5% by weight, preferably 0.05-3% by weight.
Further, as the water-soluble organic substance, for example, ethylene glycol, diethylene glycol, glycerin, etc. are suitably used, and the concentration in the aqueous solution is generally 0.02 to 5% by weight, preferably 0.1 to 3% by weight. When an acid or a water-soluble organic substance is added to water, the solubility of the phlegm is reduced, which has the effect of facilitating the precipitation of the phlegm in a later step. When mixing raw material and water and stirring to form a slurry, the amount of raw material to be mixed is generally in the range of 2 to 50% by weight, preferably 5 to 30% by weight, based on the weight of water. . In the hydrothermal reaction, the above aqueous slurry is heated at 100 to 180℃.
It is preferably carried out by heating to a temperature of 105 to 140°C.
In carrying out the hydrothermal reaction, talc, silicic anhydride, silicic acid, calcium carbonate, hemihydrous slag, soluble anhydrous slag, or a mixture thereof may be appropriately added as an additive. When using a semi-hydrated slag or a soluble anhydrous sludge as an additive, the temperature of the slurry is set to a temperature at which the semi-hydrated sludge is no longer hydrated, specifically 70°C or higher, preferably 85°C or higher.
It should be added after warming to above ℃. When adding additives, add them based on the weight of the raw material.
It is added in a proportion of 0.001 to 50% by weight, preferably 1 to 20% by weight. The hydrothermal reaction is carried out until an α-type hemiwater fibrous shell and/or a spherical shell formed substantially from a fibrous shell is obtained, and the reaction time is usually 1 to 90 minutes, preferably 3 to 60 minutes. And it is sufficient. Although this reaction time varies depending on the reaction temperature, by carrying out the reaction under pressure, it can be significantly shortened compared to the case where the reaction is carried out under normal pressure. Further, during the hydrothermal reaction, it is preferable to carry out the reaction while mixing or stirring using a means such as a stirring blade, which is especially necessary in order to obtain spherical snails. In the present invention, spherical moldings are more desirable than fibrous moldings in terms of the strength of the molded product obtained later. Excess water is removed as necessary from the aqueous slurry of the α-type hemihydrous fibrous fibrous and/or spherical fibrous slurry formed in this way, and then fibers are bonded as a reinforcing agent. As agents, water-soluble polymers (polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylamide, polyacrylic acid, polyethylene oxide, etc.), polymer emulsions (vinyl acetate emulsion, acrylic resin emulsion, etc.), hydraulic inorganic substances (water glass, Sodium silicate, alumina sol, silica sol, cement, clay, etc.) can be added as desired. Further, in the present invention, at least one of β-type hemihydrate, soluble anhydrous, and aqueous solution is added to the aqueous slurry of the hydrothermal reaction product. Note that these substances may be added before or after adding the reinforcing agent or binder. The aqueous solution herein means a supernatant liquid obtained when dihydrated solution, semi-hydrated solution, and soluble anhydrous solution are added to water, mixed, and then allowed to stand.
These substances such as β-type hemihydrate are added at a ratio of 0.01 to 5 parts by weight, calculated as calcium, per 100 parts by weight of the raw material in the slurry. Adding these substances not only eliminates the need for cooling the aqueous slurry to a predetermined temperature for the next dehydration molding process, but also eliminates the need for processing such as cooling the aqueous slurry to a predetermined temperature. A major feature is that it is difficult for semi-hydrated water to become dihydrated. Next, the aqueous slurry is subjected to dehydration molding and hydration hardening to produce a solid molded article, and these operations can be performed by conventional methods. For example, dehydration molding is performed by applying means such as compression molding, extrusion molding, casting molding, and paper forming.
It can be cured by hydration. After curing, free moisture is removed by drying or other means. The molded article thus obtained is characterized by being lightweight and having high strength.
In addition, from a process standpoint, the method of the present invention simplifies the process because it directly molds using a hydrothermal reaction slurry, allows continuous operation, and requires cooling of the aqueous slurry before the molding process. It has the following characteristics: there is no need to worry about dihydration of the raw material half-hydrate in the slurry before molding, it hardens quickly after molding, and the shrinkage of the molded product is small. Incidentally, when the proportion of spherical particles in the solid content of the aqueous slurry is high, not only the strength of the obtained molded article is high, but also the workability is improved. The products obtained by the method of the present invention have the above characteristics and are therefore extremely useful as building materials such as ceiling materials, heat insulating boards, sound absorbing boards, and partition materials. Next, the present invention will be explained in detail with reference to examples. Examples 1 to 4 3 Water 2 was charged into a glass autoclave and heated to 135°C. Next, add 200r.p.
300 g of dihydrous slag and 3 g of β-type hemihydrate sludge were charged while stirring at m. m., and reacted at 125°C for 10 minutes. The additives shown in Table 1 were added to the aqueous slurry of the obtained reaction product (mainly α-type hemihydroglobules), and a portion of the slurry was added to the papermaking surface of 100 mm x 100 mm.
Then, it was poured into a paper molding mold with a 40-mesh wire mesh. Thereafter, 5°C water was poured into the slurry to adjust the temperature of the slurry to the temperature shown in Table 1, followed by compression dehydration and paper forming. Note that the water used for cooling the slurry passed through a wire mesh, and the entire slurry could be cooled almost uniformly. 0.5 hours after molding, the mold was removed and dried at 60°C for 8 hours to obtain a molded product. Table 1 shows the experimental conditions and results. Comparative Examples 1 to 3 Same as Examples 1 to 4 except that no additive was added to the aqueous slurry of the reaction product (only Comparative Example 3 used Al ₂ (SO ₄ ) _{3.18H 2} O). A compact molded body was obtained. The results are shown in Table-1. Reference Example 1 After heating the aqueous slurry of the reaction product obtained in Example 1 and washing with methanol,
A drying treatment was carried out at ℃ for 3 hours to obtain α-type hemihydroglobules. This spherical fiber has an average fiber diameter of 1.2μ.
Formed from fibers with an average particle diameter of 200μ and a bulk density of
It was 0.12g/ ^cm3 . 300 ml of water at 30° C. was added to 80 g of this spherical clay to form a slurry, and a clay molded body was obtained in the same manner as in Example 1. The results are shown in Table-1. Example 5 Water 2 was charged into a glass autoclave and heated to 145°C. Next, add 200r.p.
Add 300g of Nisui Setsukou while stirring with m.
The reaction was carried out at 135°C for 10 minutes. The reaction product at this time was mainly α-type hemihydrate fibrous snails. Hereinafter, a molded body was obtained in the same manner as in Examples 1 to 4. The results are shown in Table-1. Comparative Example 4 A molded article was obtained in the same manner as in Example 5 except that no additive was added to the aqueous slurry of the reaction product. The results are shown in Table-1. Reference Example 5 After heating the aqueous slurry of the reaction product obtained in Example 5 and washing with methanol,
A drying treatment was carried out at ℃ for 3 hours to obtain α-type hemihydrate fibrous snails. This fibrous fiber has an average fiber diameter of
1.5μ, average fiber length 140μ, and bulk density 0.11g/cm ³ . 300 ml of water at 30° C. was added to 80 g of this fibrous clay to form a slurry, and a clay molded body was obtained in accordance with Example 1. The results are shown in Table-1. 【table】

Claims (1)

[Claims] 1. An aqueous slurry made of dihydrate, hemihydrate, soluble anhydrous or a mixture thereof, and α-type hemihydrate fibrous and/or substantially fibrous at a temperature of 100 to 180°C. The hydrothermal reaction is carried out until a spherical settsukou is obtained, and the aqueous slurry of the reaction product is
1. A method for producing a molded product, which comprises adding at least one of a semi-hydrated mold, a soluble anhydrous mold, and an aqueous mold solution, followed by dehydration molding and curing. 2. Adding at least one of β-type hemihydrate, soluble anhydrous, and aqueous solution to the aqueous slurry of the reaction product as a raw material in the slurry.
The method according to claim 1, wherein the amount is added in an amount of 0.01 to 5 parts by weight in terms of calcium per 100 parts by weight.