JPS6143314B2 - - 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 sessile, an aqueous slurry of α-type hemihydrate sessile is heated, washed with alcohol if necessary, dried to obtain α-type hemihydrate sessile, and then normal water 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. It is an object of the present invention to overcome the above-mentioned drawbacks and provide a method for producing a molded article with high strength through a simplified process while directly molding 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. The resulting aqueous slurry is cooled to 45°C or lower while satisfying the condition that 80% or more of the solid content in the slurry is semi-aqueous. The present invention provides a method for producing a molded product, which is characterized by dehydration molding and curing. 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. Adding an acid or a water-soluble organic substance to water has the effect of reducing the solubility of snails and facilitating the precipitation of snails 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 from the viewpoint of the strength of the molded product obtained later. If necessary, excess water is separated from the aqueous slurry of α-type hemihydrate fibrous slag and/or spherical sludge formed from substantially fibrous slough produced in this manner. Next, when cooling the aqueous slurry to a temperature of 45° C. or lower, it is important to cool the slurry so that the condition that 80% or more of the solid content in the slurry is semi-aqueous is satisfied. As mentioned above, α
Type half-water slurry is stable at temperatures above about 80°C, but when the temperature drops, it converts to bi-hydrous slurry.
Cool to a temperature below 45°C. Therefore, it is desirable to apply means such as flowing water at 0 to 30°C to the slurry or bringing the slurry into contact with cold heat at 0 to 30°C. Generally, the slurry should be cooled as quickly as possible, usually within 10 minutes. If the cooling temperature of the aqueous slurry is higher than 45°C, the strength of the molded product obtained will be insufficient, and if the content of hemihydrate in the solid content of the slurry is less than 80%, the molded product obtained similarly will not have sufficient strength. This is not preferable because it reduces the strength. This slurry may be added with fibers as a reinforcing agent and water-soluble polymers (polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylamide, polyacrylic acid) as a binder at any time before, during, or after cooling. , polyethylene oxide, etc.), polymer emulsions (vinyl acetate emulsion, acrylic resin emulsion, etc.), hydraulic inorganic materials (water glass, sodium silicate, alumina sol, silica sol, cement,
etc.) may be added as desired. After cooling, the aqueous slurry is dehydrated and cured by hydration to produce a solid molded article, and these operations can be carried out 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. A compact molded body is obtained in this way, and the molded body obtained by the present invention is characterized by being lightweight and having high strength. Also, from a process standpoint,
The method of the present invention simplifies the process because it directly molds using a hydrothermal reaction slurry, and has features such as continuous operation, fast curing, and small shrinkage of the molded product. ing. 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, partitioning materials, etc. Next, the present invention will be explained in detail with reference to examples. Examples 1 to 3 3 Water 2 was charged into a glass autoclave and heated to 145°C. Next, add 200r.p.
300 g of dihydric slag and 3 g of β-type hemihydrate sludge were charged while stirring at m. m., and reacted at 135°C for 10 minutes. A part of the aqueous slurry of the obtained reaction product (mainly α-type hemihydroglobules) was placed on a papermaking surface of 100 mm×
It was poured into a paper mold with a wire mesh of 100 mm and 40 mesh. After that, pour water at 5℃ and put it on the surface.
The slurry was rapidly cooled to the temperature indicated in 1. After cooling to a specified temperature, compression molding was performed. Note that the cooling water passed through the wire gauze and was able to cool the entire device almost uniformly. 0.5 hours after molding, the mold was removed and dried at 60°C for 8 hours to obtain a compact molded product. Table 1 shows experimental conditions and results.
Shown below. Comparative Examples 1 to 3 Comparative molded bodies were obtained in the same manner as in Examples 1 to 3, except that the cooling of the aqueous slurry was set at a temperature of 50 to 100°C. The results are shown in Table-1. Examples 4 and 5 3 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. Below, Example 1~
A molded body was obtained according to 3. Table of results-1
Shown below. Comparative Examples 4 and 5 A molded body was produced in the same manner as in Examples 4 and 5, except that during cooling of the aqueous slurry, the proportion of half-water solids in the solid content of the slurry was adjusted to be less than 80%. 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 3° C. was added to 80 g of this spherical clay to form a slurry, and a clay molded article was obtained in the same manner as in Example 1. The results are shown in Table-1. Example 6 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 136°C for 8 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 3. The results are shown in Table-1. Comparative Example 6 A molded body was obtained in the same manner as in Example 6 except that the cooling of the aqueous slurry was set to 100°C. The results are shown in Table-1. Reference Example 2 After heating the aqueous slurry of the reaction product obtained in Example 6 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
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 A spherical shape formed from α-type hemihydrous fibrous slag and/or substantially fibrous sludge by making an aqueous slurry of dihydrate sludge, hemihydrate sludge, soluble anhydrous sludge, or a mixture thereof at a temperature of 100 to 180°C A hydrothermal reaction is carried out until a solid is obtained, and the resulting aqueous slurry is cooled to 45°C or less while satisfying the condition that 80% or more of the solid content in the slurry is semi-hydrated, and then dehydrated and molded. A method for producing a molded article characterized by hardening.