JPH07267711A - Hydraulic inorganic composition for dehydration press molding and production of hydraulic inorganic molded body using same - Google Patents

Abstract

PURPOSE:To improve flowability and mold releasability without leaking a slurried mixture from a gap in a mold at the time of pressing by incorporating a hydraulic inorg. material, specified fine powdery silica and mineral fibers. CONSTITUTION:A hydraulic inorg. material is blended with 20-60wt.% fine powdery silica having 0.5-10mum weight average particle diameter, 5-40wt.% mineral fibers and 10-50wt.% water and the resultant blend is further blended with reinforcing fibers each having 1mum to 1mm diameter and 1-20mm length, a water-soluble polymer and an inorg. filler if necessary to obtain the objective hydraulic inorg. compsn. for dehydration press molding. This compsn. is filled into a mold, subjected to dehydration press molding and cured in an autoclave at 100-200 deg.C for 1-10hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic inorganic composition for dewatering press molding, and a method for producing a hydraulic inorganic molded article using the same.

[0002]

2. Description of the Related Art A hydraulic inorganic material molding such as cement is used as a building member such as a floor, a wall or a roof.
These members are formed by a papermaking method, an extrusion method, a dewatering press method, or the like. Among them, the dewatering press method is particularly suitable for a member or the like that requires a complicated shape on the surface because of its excellent design.

By the way, asbestos-cement molded boards having relatively high strength are used as these building members. Asbestos has the effect of improving the moldability during molding and improving the mechanical strength after curing, but in recent years its carcinogenicity has been regarded as a problem, and currently, asbestos is used to obtain high strength. A method of manufacturing the body is desired. As a method for producing asbestos-free and high-strength cement compacts, for example, Japanese Unexamined Patent Publication
As described in Japanese Patent Laid-Open No. 4-64804, there is a method in which a spherical inorganic aggregate such as silica fume, a synthetic fiber, and a water-soluble polymer are used and the mixture is molded by a dehydration press. According to the above-mentioned method, by using silica fume, the pozzolanic reaction proceeded and the strength could be increased in the short and long term after curing.

[0004]

However, silica fume has the problems that it is expensive and has a limited amount of resources, and that it is an industrial waste and its quality is unstable and the quality of the molded product varies. In addition, synthetic fibers cannot be used when attempting autoclave curing to further increase strength, and when silica fume is added without the addition of synthetic fibers, the flow characteristics change, so that a slurry-like mixture is produced from the gaps in the mold during pressing. However, there is a problem in that a part of the molded product sticks to the mold without being separated from the mold because the mold release property after pressing is deteriorated.

Therefore, an object of the present invention is to provide a hydraulic inorganic composition for dewatering press molding which solves the above conventional problems, and a method for producing a hydraulic inorganic molding using the same.

[0006]

[Means for Solving the Problems]
Is a hydraulic inorganic substance and has a weight average particle size of 0.5 to 10 μm.
m is a finely divided silica stone and a mineral fiber as main components, which is a hydraulic inorganic composition for dehydration press molding, and 2 of the present invention comprises dehydration press molding the above composition to cure and cure. A third aspect of the present invention is a method for producing a hydraulic inorganic molded article, characterized in that the above curing is autoclave curing.

The present invention will be described in more detail below. As the hydraulic inorganic material used in the present invention, commercially available ordinary Portland cement, early-strength Portland cement, alumina cement, blast furnace cement and the like are used.
The fine silica powder has a weight average particle diameter of 0.5 to 10 μm,
It is preferable to use a material pulverized to 1 to 5 μm. If it is less than 0.5 μm, the agglomerates of fine powder silica do not disperse as they agglomerate during mixing, and the strength of the molded product after curing is difficult to develop. In addition, crushing is extremely time-consuming and uneconomical.
When it exceeds 10 μm, the effect of the finely divided silica stone filling the gaps of the hydraulic inorganic substance to increase the strength is hard to occur, and the strength of the molded body after curing is hard to be expressed. In addition, the mixture does not spread sufficiently during dewatering press, the transferability of the mold becomes poor, and it becomes difficult to obtain a molded article with good design. Fine silica is 20 of total solids
-60% by weight, preferably 25-40% by weight.
If it is less than 20%, the effect of addition of finely divided silica stone is unlikely to occur, and the strength of the molded body after curing is difficult to develop. Further, the mixture does not spread sufficiently during dewatering press, and it is difficult to reach all the corners of the mold. If it is added in excess of 60%, the amount of the hydraulic inorganic substance added will be small, and the strength of the molded body after curing will be difficult to develop.

When silica fume is used instead of fine silica powder, aggregates of silica fume do not disperse into primary particles and strength is difficult to develop. Further, if silica fume is used and no reinforcing fiber is added, the mold releasability after pressing is deteriorated, and a part of the molded body sticks without being separated from the mold frame, which is not preferable. As the mineral fiber, wollastonite, sepiolite or the like can be used. Asbestos is not preferred because of its carcinogenic problems. The above mineral fibers are 5 to 40% by weight, and preferably 10 to 40% by weight based on the total solid content.
Add 30% by weight. In the present invention, the addition of finely divided silica increases the fluidity of the mixture and allows the mixture to reach every corner of the mold, but since reinforcing fibers other than mineral fibers are not necessarily required, these reinforcing fibers are If the amount of mineral fibers added is less than 5% when not added, leakage from the mold occurs during pressing, making it difficult to produce a molded body. If it is added in excess of 40%, the compact compacted by press molding will expand again due to the elasticity of the mineral fibers at the time of depressurization, and the strength of the compact after curing will be difficult to develop.

The molding water is kneaded in a proportion of 10 to 50% by weight, preferably 20 to 40% by weight, based on the total solid content.
When it is less than 10%, the dispersibility of the composition is lowered. Further, since the fluidity is deteriorated, the kneaded product does not sufficiently expand during the dehydration press molding. If it exceeds 50%, material separation occurs during dehydration press molding, and a uniform molded body cannot be obtained. In the present invention, reinforcing fibers may be further added if necessary. The reinforcing fiber may be any one depending on the performance desired to be imparted to the molded body. For example, organic fibers such as vinylon, polypropylene, polyethylene, polyester, aramid, polyamide and pulp, metal fibers such as steel fibers and stainless steel fibers, inorganic fibers such as carbon, ceramics and glass can be used. The reinforcing fiber has a diameter of 1 μm.
Those having a length of ˜1 mm and a length of 1 to 20 mm are preferable. Since autoclave curing is performed in 3 of the present invention, the fibers that can be added among the above-mentioned reinforcing fibers are limited, but any fiber having heat resistance and heat resistant alkali resistance can be used. By the addition of the reinforcing fiber, toughness, impact resistance,
Alternatively, workability for cutting, cutting, etc. is improved.

In the present invention, a water-soluble polymer may be added if necessary. As the water-soluble polymer, for example, methyl cellulose, polyvinyl alcohol, sodium polyacrylate, polyacrylamide, etc. can be used. In the present invention, an inorganic filler may be added if necessary. As the inorganic filler,
For example, known substances such as silica sand, river sand, fly ash, blast furnace slag, clay, and calcium carbonate, which are added to the cement molded product, can be used.

Any method may be used for mixing the composition thus blended, for example, a mortar mixer, an omni mixer, an Erich mixer, or the like can be used. It is preferable to use a method of mixing while applying a shearing force, such as an Erich mixer, because the kneading time can be shortened. The mixture obtained by the above method is shaped by dehydration press molding. The dehydration method may be a method in which water is naturally squeezed out at the time of pressing, or a method of pressing while drawing water in a vacuum. At this time, a molded product having a complicated shape can be obtained by applying a predetermined shape to the mold.

The molded body obtained by the above method may be cured by a known method, and any of natural curing, steam curing, and autoclave curing is possible. In particular, when autoclave curing is used, the C—S—H gel and calcium hydroxide produced by the hydration reaction of the hydraulic inorganic substance cause a hydrothermal reaction with the finely divided silica stone to promote the crystallization of the gel, so that the strength is improved. Can be significantly increased. The conditions for autoclave curing are a temperature of 100 ° C to 200 ° C and a time of 1
10 hours is preferable.

[0013]

By including fine silica powder having a weight average particle diameter of 0.5 to 10 μm, the fine silica powder can fill the gaps of the hydraulic inorganic substance to enhance the strength, and the mixture can be formed during dehydration pressing. Since it extends sufficiently, it reaches all the corners of the mold and a molded product can be easily obtained.

Further, since the mineral fibers have an effect of holding the hydraulic inorganic substance and the finely powdered silica stone by containing the mineral fibers, it becomes possible to perform molding without leakage from the mold during pressing. Further, by subjecting the molded body obtained by the dehydration press to autoclave curing, C-S- produced by the hydration reaction of the hydraulic inorganic substance.
Since the H gel and calcium hydroxide undergo a hydrothermal reaction with the finely divided silica stone to promote the crystallization of the gel, the strength of the product can be significantly increased.

[0015]

EXAMPLES Examples and comparative examples of the present invention will be described below.

[0016]

[Examples 1 to 4 and Comparative Examples 1 to 5] In Example 1, cement, fine silica powder, wollastonite, and water having the composition shown in Table 1 were mixed with an Eichrich mixer (R02, manufactured by Ehrlich Japan Ltd.). Mix for 4 minutes, then mix this mixture for 30 minutes.
15 mm diameter in the center of a 3 x 310 mm rectangular formwork
Placed in a lump of about cm, and using a dehydration press molding machine (manufactured by Atago Engineering Co.), a molding pressure of 70 kg / cm ²
Was dehydrated and pressed for 10 seconds to obtain a molded body. At that time, observing whether there is a leak from the formwork, observing whether the mixture has spread to every corner of the formwork, and whether the molded body sticks to the formwork at all and can be released from the mold. Was observed.

This molded body was cured by the method shown in Table 1. The resulting product was dried at 105 ° C. for 24 hours and then the bending strength was measured. In Examples 2 to 4 and Comparative Examples 1 to 5, molding was performed by changing the composition as shown in Table 1. The raw materials used in each example are as follows. Cement: Union made, ordinary Portland cement Fine silica stone: Bird roof silica stone finely crushed product, weight average diameter 3 μm Wollastonite: Kawatetsu Mining Co., B type Coarse crushed silica stone: Ukusu silica stone crushed product, weight average diameter 20 μm Silica fume: Union Chemical formation, weight average diameter 0.1 μm

[0018]

[Table 1]

In Table 1, "automatic" in the section "curing method" means that curing was carried out in an autoclave at 180 ° C for 4 hours. The term "steam + auto" means that the curing was performed for 5 hours under saturated steam at 60 ° C and then for 4 hours in an autoclave at 180 ° C. The term "steam" means that curing was performed for 48 hours under saturated steam at 60 ° C. In Table 1, "leakage from the mold" is a determination as to whether there is a leak from the mold during pressing. X indicates that there is a leak and it is difficult to produce a molded body. "Liquidity" in Table 1
Is a determination as to whether or not the mixture has flowed to every corner of the mold after the dewatering press. X indicates that the mixture did not spread well and did not flow to the corners of the mold.

In Table 1, "releasability" is a judgment as to whether or not the molded product can be released from the mold without remaining at all. X indicates that a part of the molded body remains in the mold frame at the time of mold release. In Table 1, “Moldability” means that there is no leakage from the mold, the mixture flows into every corner of the mold and is pressed, and when the mold is released, no molded product remains in the mold at all. age,
Other than that was marked with x.

[0021]

EFFECTS OF THE INVENTION By using the composition and the production method of the present invention, there is no leakage from the mold during pressing,
Further, the mixture exhibits fluidity such that it flows to every corner of the mold, and further, the dehydration press molding can be easily carried out without a part of the molded product obtained at the time of mold release sticking to the mold. Further, it is possible to manufacture a product having excellent strength as a building member.

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Claims (3)

[Claims] 1. A hydraulic inorganic substance having a weight average particle diameter of 0.
A hydraulic inorganic composition for dehydration press molding, which comprises 5 to 10 μm of finely divided silica stone and mineral fibers as main components. 2. A method for producing a hydraulic inorganic molded body, which comprises subjecting the composition according to claim 1 to dehydration press molding and curing and curing. 3. The method for producing a hydraulic inorganic molded body according to claim 2, wherein the curing is an autoclave curing.