JP2000211958A - Dehydration press molding product and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dehydration press molding product having excellent toughness and quality as a building member. SOLUTION: This method for producing dehydration press molding product comprises subjecting a composition comprising (A) a hydraulic inorganic substance, (B) crystalline inorganic filler having 10 μm to 2 mm average particle diameter, (C) slurry obtained by previously dispersing amorphous silica having 0.01-1 μm average particle diameter, (D) a synthetic fiber and (E) a water reducing agent to dehydration press molding and then curing and hardening the molded composition. According to the method, dehydration press molding product can readily be obtained without causing leakage from a frame mold when pressed. The resultant product is useful as a member for building, because it has high flexural strength in dried state or water-saturated state and is excellent in external appearance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dewatered press formed body and a method for producing the same.

[0002]

2. Description of the Related Art As building members such as floors, walls and roofs, molded articles made of hydraulic inorganic substances such as cement are used. These members are formed by a papermaking method, an extrusion method, a dewatering press method, or the like. Of these, the dewatering press method is particularly suitable for members requiring a complicated shape on the surface because of its excellent design.

[0003] By the way, asbestos-cement molded boards having relatively high strength have conventionally been used as these building members. Asbestos has the effect of improving the moldability at the time of molding and improving the mechanical strength after curing, but its carcinogenicity has been regarded as a problem in recent years, and at present it is a molding that obtains high strength without using asbestos There is a need for a body manufacturing method. As a method for producing an asbestos-free and high-strength cement molded article, for example, as described in JP-A-64-64804, a water-soluble polymer substance, one of which is spherical in shape, and Two or more inorganic fillers, which are porous and have a high specific surface area and are amorphous silica fine particles, and synthetic fibers;
There is a method in which cement and water are rocked and mixed, and the resulting mixture is placed in a mold that can be opened and closed, and is shaped by pressing.

[0004]

Problems to be Solved by the Invention
In Patent Document 4, a molded article is produced using cement, fly ash, silica fume, vinylon fiber, and methylcellulose. However, when only an amorphous substance is used as the filler as described above, although the bending strength in a saturated state is increased, a fine crack is generated in a molded body in a dry state, and the Young's modulus is reduced, and therefore, There was a problem that the bending strength was lowered.

Therefore, when molding is performed using only two or more types of crystalline silica as a filler, the bending strength in a dry state increases, but the bending strength in a saturated state decreases. There was a problem of doing it. In addition, in this method, when the filter cloth is extremely dirty, a part of the molded body is stuck to the filter cloth when the molded body is peeled off from the filter cloth after molding, and the molded body is deformed and cracks are formed. There were also problems.

Accordingly, the present invention solves the above-mentioned conventional problems and provides a product having excellent strength and quality, particularly as a building member.

[0007]

That is, the first aspect of the present invention is to provide a hydraulic inorganic substance (A), a crystalline inorganic filler (B),
A molded article obtained by dehydrating and molding a composition containing an amorphous silica slurry (C), a synthetic fiber (D) and a water reducing agent (E), wherein the solids of (A), (B) and (C) Total of 100 minutes
(A) is 30 to 80 parts by weight, and (B) is 1 part by weight.
0 to 69 parts by weight, the solid content of (C) is 1 to 10 parts by weight,
(D) is 0.1 to 4 parts by weight, and (E) is 0.05 to 4 parts by weight.
A dewatered press-formed body characterized in that it is 2 parts by weight.

A second aspect of the present invention is a hydraulic inorganic substance (A),
A crystalline inorganic filler (B) having an average particle diameter of 10 μm to 2 mm, a slurry (C) in which amorphous silica having an average particle diameter of 0.01 to 1 μm is previously dispersed in water, a synthetic fiber (D), and water reduction A method for producing a dewatered press-formed body, comprising dehydrating press-molding a composition containing the agent (E) and curing and curing the composition.

Hereinafter, the present invention will be described in more detail. As the hydraulic inorganic substance (A) 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 amount of the hydraulic inorganic substance (A) to be added is 30 to 30 parts by weight based on a total of 100 parts by weight of the solid content of the hydraulic inorganic substance (A), the crystalline inorganic filler (B), and the amorphous silica slurry (C). 80 parts by weight, preferably 35 to 70 parts by weight, more preferably 40 to 60 parts by weight.

The average particle size used in the present invention is 10 μm to 2 m.
The crystalline inorganic filler (B) of m is not particularly limited as long as it does not significantly inhibit the action of any constituent material used in the production method of the present invention.
Examples include silica sand, river sand, bentonite, mica, calcium carbonate, and the like, and pulverized silica is preferred. Further, two or more crystalline inorganic fillers may be added. When an amorphous filler is used as an inorganic filler, fine cracks are generated in the molded body when dried, and the Young's modulus is reduced and the bending strength is also reduced. By the way, dewatering press molding is divided into a stage in which a mixture is filled in a mold at an early stage of pressing, and a stage in which the mixture is completely filled and pressed and dewatered. The crystalline inorganic filler also has a function of performing sufficient dehydration when pressurized.

The average particle size of the crystalline inorganic filler (B) is 1
Those having a thickness of 0 μm to 2 mm, preferably 12 μm to 500 μm, more preferably 15 μm to 100 μm are used. Here, the average particle size is a value obtained by measuring the median diameter of the mass using a laser diffraction type particle size distribution measuring device. When the average particle size is less than 10 μm, the tendency of retaining water between the crystalline inorganic filler particles becomes stronger, so that dewatering at the time of pressurization is facilitated to prevent the mixture from leaking from the mold. The effect of the material cannot be obtained and molding becomes difficult. Further, when the average particle size exceeds 2 mm, the mixture does not sufficiently extend to every corner of the mold when the mixture is filled in the mold, and further, separation of water from the mixture occurs,
The transferability of the mold is poor.

The amount of the crystalline inorganic filler (B) added is 100 parts by weight in total of the solid content of the hydraulic inorganic substance (A), the crystalline inorganic filler (B), and the amorphous silica slurry (C). 10 to 69 parts by weight, preferably 23 to 64 parts by weight, more preferably 34 to 58 parts by weight. When the addition amount is less than 10 parts by weight, the effect of the crystalline inorganic filler, which facilitates dehydration at the time of pressurization and prevents the mixture from leaking from the mold, is hardly exhibited. When the addition amount exceeds 69 parts by weight, the mixture does not sufficiently extend to all corners of the mold when the mixture is filled in the mold, and further, there is a tendency that moisture is separated from the mixture. Transferability is deteriorated.

The average particle size of the primary particles of the amorphous silica slurry (C) used in the present invention is 0.01 to 1 μm, preferably 0.05 to 0.8 μm, more preferably 0.1 to 0.1 μm. 6 μm. When the average particle size is larger than 1 μm, the fluidity of the mixture becomes poor when the mixture is filled in the mold, and furthermore, the effect of the amorphous silica to retain moisture cannot be obtained, and the water content of the mixture is reduced. The mixture does not extend sufficiently due to separation.

Further, when crystalline silica is used, the amorphous silica does not cause a pozzolanic reaction that consumes calcium hydroxide generated as a result of hydration of cement, so that the bending strength in a saturated state decreases. Also, by using a slurry obtained by dispersing amorphous silica in water, the stain on the filter cloth is reduced, so that when the molded body is peeled off from the filter cloth after molding, a part of the molded body is stuck to the filter cloth. It is difficult to cause such a problem that the molded article is deformed and cracked.
Further, the color unevenness of the molded article is reduced, and the coating is hardly peeled off. Further, the amorphous silica is easily dispersed into single particles, and enters the gap between the hydraulic inorganic substance and the crystalline inorganic filler, so that the filling degree is increased and the strength is improved. Further, by forming the slurry, the trouble that the powder is agglomerated in the pipe and the pipe is blocked is less likely to occur. In addition, dust is hardly generated, and it is excellent in environmental health.

As the amorphous silica slurry, for example, silica fume slurry, microsilica slurry and the like are used. The solid concentration of the amorphous silica slurry is 7
It may be 0% or less. The addition amount of the solid content of the amorphous silica slurry (C) is 100 parts by weight in total of the hydraulic inorganic material (A), the crystalline inorganic filler (B) and the solid content of the amorphous silica slurry (C). The amount is 1 to 10 parts by weight, preferably 1.5 to 7 parts by weight, more preferably 2 to 6 parts by weight.

If the addition amount is less than 1 part by weight, the mixture does not extend sufficiently when the mixture is filled in the mold, and it is difficult to reach every corner of the mold. Further, since the rate of the pozzolanic reaction in which the amorphous silica consumes calcium hydroxide generated by hydration of the cement becomes slow, the flexural strength in a saturated state becomes low. Conversely, if the amount exceeds 10 parts by weight,
The dewatering property of the mixture is reduced, and the mixture leaks from the mold when pressurized, and cannot be molded.

In the present invention, the main purpose of adding the synthetic fiber (D) is to increase the toughness of the molded article.
There is no particular limitation as long as it is suitable for this purpose. For example, polypropylene, vinylon, polyethylene, polyester, aramid, polyamide and the like can be used, and polypropylene and vinylon are particularly preferable. Even if cracks are formed in the molded article by adding the synthetic fibers, the development can be suppressed, so that the toughness is significantly improved.

The synthetic fiber (D) is used in an amount of 0.1 to 4 parts by weight based on a total of 100 parts by weight of the solid content of the hydraulic inorganic substance (A), the inorganic filler (B) and the amorphous silica slurry (C). , Preferably 0.2 to 2 parts by weight, more preferably 0.3 to 1.5 parts by weight. If the addition amount is less than 0.1 part by weight, the effect of increasing the toughness of the synthetic fiber is less likely to be exhibited. If the addition amount is more than 4 parts by weight, the dispersibility of the fibers tends to decrease, the uniformity of the molded body also decreases,
The bending strength also decreases.

In the present invention, synthetic fibers having a diameter of 1 μm to 1 mm can be used, preferably 5 μm to 0.5 mm, particularly preferably 10 μm to 0.
2 mm. . Further, the length of the fiber can be 1 to 50 mm, preferably 2 to 30 mm, particularly preferably 3 to 20 mm. If the fiber diameter is smaller than 1 μm or the fiber length is larger than 50 mm, it is difficult to obtain a uniform molded body because the fibers are not well dispersed. When the diameter is larger than 1 mm, the mixture does not easily extend sufficiently when the mixture is filled in the mold. When the length is smaller than 1 mm, the effect of increasing the toughness is hardly exhibited.

As the water reducing agent (E) used in the present invention, conventionally known water reducing agents can be used, and lignin sulfonates, oxycarboxylates, polyalkylallyl sulfonates, melamine formalin resin sulfonates, aromatic polyamines, etc. Ring condensate sulfonate and the like can be used. The water reducing agent (E) has a function of suppressing the rate of dehydration from the filter cloth surface during pressurization without deviating the optimum amount of water, and as a result, reduces the surface roughness in the thick part of the molded body. If you do not use a water reducing agent,
The dewatering speed from the filter cloth surface increases, and the internal water movement cannot keep up with it, and only the mortar near the filter cloth surface is dehydrated and solidified, and especially in thick parts, the surface opposite to the filter cloth surface becomes rough. . However, since the dewatering speed from the filter cloth surface is suppressed by adding the water reducing agent, even if the mortar near the filter cloth surface is dewatered, moisture is immediately supplied from the inside, and both the filter cloth side and the opposite side are removed. Uniform dehydration is performed, and as a result, the surface of the thick part is also formed neatly.

The water reducing agent (E) is added in an amount of 0.1 to 100 parts by weight of the total of the solid content of the hydraulic inorganic substance (A), the crystalline inorganic filler (B) and the amorphous silica slurry (C). 0
It is 5 to 2 parts by weight, preferably 0.1 to 1 part by weight, more preferably 0.2 to 0.5 part by weight. 0.05 added
When the amount is less than the weight part, the effect of the water reducing agent of improving the moldability in the thick part is hardly exhibited. If the addition amount exceeds 2 parts by weight, the dehydration rate becomes so slow as to adversely affect the productivity, which is not practical.

In the present invention, the amount of molding water added is based on 100 parts by weight of the solid content of the hydraulic inorganic substance (A), the crystalline inorganic filler (B) and the amorphous silica slurry (C). The amount is preferably 10 to 50 parts by weight, and more preferably 20 to 40 parts by weight. The amount of molding water added is 1
If the amount is less than 0 parts by weight, the dispersibility of the composition decreases. Further, since the fluidity is reduced, the mixture is not sufficiently elongated when the mixture is filled in the mold. If the amount is more than 50 parts by weight, when the mixture is filled in the mold, water is easily separated from the mixture, and the transferability of the mold is reduced. Further, since fine powder is dispersed in the dewatered water, wastewater treatment is required. However, when the amount exceeds 50 parts by weight, the load of the wastewater treatment becomes extremely large.

In the present invention, a water-soluble polymer can be added in a very small amount that does not cause the problem of mold leakage. Examples of the water-soluble polymer include methyl cellulose, polyvinyl alcohol, sodium polyacrylate, and polyacrylamide. However, if the added amount is large, the mixture becomes poor in dehydration, leaks from the mold at the time of pressurization, and becomes difficult to mold.

As a mixer for mixing the composition thus mixed, for example, a mortar mixer, an omni mixer, an Erich mixer or the like can be used. In the present invention, the mixture obtained by the above method is shaped by dewatering press molding. The dehydration press is a method in which the mixture is put into a mold that can be opened and closed, and pressing and dehydration are performed at the same time.As a dehydration method, a method in which water is naturally squeezed out at the time of pressing may be used, or water may be removed in a vacuum. A method of pressing while pulling may be used. At this time, a molded article having a complicated shape can be obtained by giving the mold a predetermined shape.

The composition of the present invention has better fluidity than conventional compositions and prevents separation of water from the mixture when the mixture is filled in a mold. Therefore, the composition is prepared before pressing. There is no need to fill near the edges of the form, and the mixture can be spread to all corners of the form by simply placing the mixture in bulk near the center of the form. In addition, the pressing speed is 1 to
Even at a high speed such as 10 cm / sec, molding can be performed without causing leakage from the mold.

Curing of the molded body obtained by the above method may be carried out by any method, and any of natural curing, steam curing and underwater curing is possible. Autoclave curing is also possible up to a temperature that the synthetic fibers can withstand. Autoclave curing conditions depend on the type of synthetic fiber used,
The temperature is preferably 100 ° C. to 180 ° C., and the time is preferably 1 to 10 hours.

In the present invention, the average particle size is from 10 μm to 2 μm.
By containing the crystalline inorganic filler of 1 mm, the bending strength in a dry state is improved. In addition, since the crystalline inorganic filler has an effect of improving the dewatering property of the mixture, dehydration can be facilitated at the time of pressurization, and the mixture can be molded without leaking from the mold.

Further, by containing amorphous silica having an average particle size of 0.01 to 1 μm, the mixture is contained in the mold because the amorphous silica retains water and prevents the separation of water from the mixture. When it is filled, it extends sufficiently, reaches every corner of the mold, and can easily obtain a molded body. Furthermore, since the calcium hydroxide produced as a result of the hydration of the cement reacts with the amorphous silica and is consumed, a pozzolanic reaction occurs, so that the bending strength in a saturated state can be increased.

Further, by using a slurry obtained by dispersing amorphous silica in water to form a slurry, the stain on the filter cloth is reduced. Problems such as sticking and deformation of the molded article and cracking are unlikely to occur. Further, the color unevenness of the molded article is reduced, and the coating is hardly peeled off. Further, the amorphous silica is easily dispersed into single particles, and enters the gap between the hydraulic inorganic substance and the crystalline inorganic filler, so that the filling degree is increased and the strength is improved. Further, by forming the slurry, the trouble that the powder is agglomerated in the pipe and the pipe is blocked is less likely to occur. In addition, dust is hardly generated, and it is excellent in environmental health.

Further, by adding synthetic fibers,
The product can have toughness. Further, by adding the water reducing agent, the dewatering speed from the filter cloth surface can be suppressed without deviating the optimum amount of water, so that the surface roughness at the thick portion can be reduced.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

[0032]

The present invention will be described more specifically with reference to the following examples and comparative examples. The raw materials used in the examples and comparative examples are as follows. (A) Cement: Ordinary Portland cement (B) Crushed silica 1: Pulverized silica, average diameter 15 μm (Comparative example) Crushed silica 2: Pulverized silica, average diameter 20 μm (Comparative example) Fly ash: Average diameter 15 μm (C) Silica Fume Slurry: Concentration 65%, Average Diameter 0.2 μm (Comparative Example) Silica Fume Powder: Average Diameter 0.2 μm (Comparative Example) Finely Pulverized Silica: Finely Pulverized Silica, Average Diameter 3 μm (D) Synthetic Fiber: Vinylon Fiber, 14 μm in diameter and 4 mm in length (E) Water reducing agent: β-naphthalenesulfonic acid formalin highly condensate

[0033]

Examples 1 and 2 and Comparative Examples 1 to 5 Cement, crystalline inorganic filler and silica fume in the amounts shown in Table 1 were mixed for 1 minute using an omni mixer. Thereafter, water was added and mixed for 2 minutes, and vinylon fiber was added and mixed for 2 minutes to prepare a mixture. Next, this mixture was placed in a lump having a diameter of about 20 cm at the center of a 440 × 330 mm mold, and was pressed by a dehydration press molding machine at a pressing speed of 5 cm / sec and a pressure of 70 kg.
A vacuum dehydration press for removing water by depressurizing from one side at a pressure of / cm 2 was performed for 10 seconds to obtain a molded product having a minimum thickness of 8 mm.

At this time, with respect to the peeling from the filter cloth, the manner of peeling was visually observed. The obtained molded body is 60 ° C.
Cured under conditions of 95% RH for 12 hours. From the obtained product, a test piece was cut into a size of 25 mm in width and 110 mm in length. What was soaked in clear water for 24 hours was made saturated,
The measurement was performed by a three-point bending test with a span of 90 mm. The loading direction was the direction from the front to the back of the product, and the crosshead speed was 1 mm / min.

With respect to the surface roughness, the appearance of the front side surface of a portion having a thickness three times that of the general portion was visually determined. The color unevenness was visually observed. As shown in Examples 1 and 2 in Table 1, the dewatered molded article of the present invention had high bending strength, and was good in all of peeling from the filter cloth, surface roughness, and uneven color.

On the other hand, the molded articles other than the present invention were inferior in moldability and various performances as compared with the products of the present invention as shown in Comparative Examples in Table 1. First, in Comparative Example 1, although the amount of the crystalline inorganic filler added was larger than the claimed range, the transferability of the mold deteriorated and the surface became rough. In addition, since silica fume is used as a powder instead of slurry,
Peeling from the filter cloth and poor color unevenness were observed.

In Comparative Example 2, although the amorphous silica was not added, the flexural strength was low. Further, no water reducing agent was added, resulting in surface roughness. In Comparative Example 3, although the added amount of the amorphous silica was larger than the claimed range, the mixture was dehydrated and leaked from the mold, and molding was not possible. In Comparative Example 4, although the amount of the water reducing agent added was larger than the claimed range, the dewatering speed was extremely slow, and dehydration was practically impossible and molding could not be performed.

In Comparative Example 5, although finely divided silica, which is crystalline silica, was used instead of amorphous silica, the bending strength was low. Also, no water reducing agent was used, resulting in surface roughness.

[0039]

[Table 1]

[0040]

EFFECTS OF THE INVENTION By using the production method of the present invention, when the mixture is filled in the mold, it exhibits good fluidity such that it flows to every corner of the mold without causing separation of moisture. In addition, dewatering press molding can be easily performed without causing leakage from the mold frame during pressurization. Also, cracks that adversely affect durability are less likely to occur.

The product obtained according to the present invention is dried,
In a saturated state, both have high bending strength and high toughness. In addition, it can be molded neatly even in a part where it is difficult to mold it thickly, and is excellent in appearance due to less color unevenness. For this reason, a product exhibiting excellent properties as a building member can be manufactured.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C04B 14:06 16:06 111: 20 24:22)

Claims (2)

[Claims] 1. A composition containing a hydraulic inorganic substance (A), a crystalline inorganic filler (B), an amorphous silica slurry (C), a synthetic fiber (D) and a water reducing agent (E) is subjected to dehydration molding. (A) is 30 to 80 parts by weight, and (B) is 10 to 69 parts by weight, based on a total of 100 parts by weight of solids of (A), (B) and (C). , The solid content of (C) is 1 to
10 parts by weight, 0.1 to 4 parts by weight of (D), and (E)
Is from 0.05 to 2 parts by weight. 2. A hydraulic inorganic substance (A) having an average particle size of 10
μm to 2 mm of a crystalline inorganic filler (B), slurry of amorphous silica having an average particle diameter of 0.01 to 1 μm in water (C), synthetic fiber (D), and water reducing agent (E) A method for producing a dehydrated press-formed body, comprising dehydrating press-molding a composition containing the composition and curing and curing the composition.