JP2002248613A - Method for manufacture of dehydrating-press-molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacture of a high quality dehydrating- press-molded body which is excellent in bending strength and toughness. SOLUTION: The method for manufacturing the dehydrating-press-molded body comprises the steps of molding a composition containing hydraulic inorganic material, a crystalline inorganic filler 10 μm to 2 mm in average particle size, noncrystalline silica 0.01 to 1 μm in average particle size and a synthetic fiber by dehydrating pressing and then hardening the molded body by curing. The temperature of the composition at start of molding is set at 25 to 45 deg.C. Therefore, leakage from a form is not generated in pressing, and the dehydrating press molded body can be easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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. By the way, conventionally, asbestos cement molded plates having relatively high strength have 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.

[0003] As a method for producing an asbestos-free and high-strength cement molding, for example, as described in JP-A-64-64804, a water-soluble polymer substance and one of them are used.
A composition obtained by rocking and mixing two or more kinds of inorganic fillers, which are spherical, porous, amorphous silica fine particles having a high specific surface area, synthetic fiber, cement, and water. There is a method in which an object is placed in a mold that can be opened and closed, and is shaped by pressing.

Japanese Patent Application Laid-Open No. 64-64804 discloses cement, fly ash, silica fume, vinylon fiber,
A molded article is produced using 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 using only two or more types of crystalline silica as a filler, conversely,
Although the bending strength in a dry state is increased, the bending strength in a saturated state is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a product having excellent strength and quality as a building member.

[0006]

That is, the first aspect of the present invention is a hydraulic inorganic substance (A) having an average particle diameter of 10 μm to 2 m.
m of a crystalline inorganic filler (B) having an average particle size of 0.01 to 1
In a method for producing a dehydrated press molded body in which a composition containing amorphous silica (C) and synthetic fiber (D) having a thickness of μm is subjected to dehydration press molding and curing and curing, the temperature of the composition at the start of molding is 2
A method for producing a dewatered press molded body, which is performed at 5 ° C to 45 ° C.

A second aspect of the present invention is that the amount of the hydraulic inorganic substance (A), the crystalline inorganic filler (B), the amorphous silica (C) and the synthetic fiber (D) is set to (A) ), (B) and (C) in a total of 100 parts by mass,
80 parts by mass, (B) is 10 to 69 parts by mass, (C) is 1 to
The method according to claim 1, wherein 10 parts by mass and (D) are 0.1 to 4 parts by mass. 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) added is as follows: the hydraulic inorganic substance (A), the crystalline inorganic filler (B),
And a total of 100 parts by mass of the amorphous silica (C),
Preferably 30 to 80 parts by mass, more preferably 35 to 7 parts by mass.
0 parts by mass, more preferably 40 to 60 parts by mass.

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 crushed 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 easily formed in the molded body when dried, the Young's modulus is easily reduced, and the bending strength is also easily reduced. The dewatering press molding is divided into a stage in which the composition is filled into a mold frame at an early stage of pressing, and a stage in which the filling of the composition is completed, followed by pressurization and dehydration. The crystalline inorganic filler also has a function of performing sufficient dehydration when pressurized.

[0010] The crystalline inorganic filler (B) has an average particle size of 10 µm to 2 mm, preferably 10 µm to 500 µm.
m, more preferably 10 μm to 100 μm. 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 to retain water between the crystalline inorganic filler particles becomes stronger, and therefore, the crystalline inorganic filler that facilitates dehydration during pressurization and prevents leakage of the composition from the mold. It becomes difficult to obtain the effect of the filler, and molding becomes difficult. When the average particle size exceeds 2 mm,
When the composition is filled in the mold, the composition does not sufficiently extend to every corner of the mold, and further, water is separated from the composition, and the transferability of the mold tends to deteriorate.

The crystalline inorganic filler (B) is preferably used in an amount of 100 parts by mass in total of the hydraulic inorganic substance (A), the crystalline inorganic filler (B), and the amorphous silica (C).
0-69 parts by mass, more preferably 23-64 parts by mass, even more preferably 34-58 parts by mass. The amount is preferably 10 parts by mass or more from the viewpoint of facilitating dehydration during pressurization and preventing leakage of the composition from the mold, and 69 parts by mass or less from the viewpoint of transferability of the mold. The average particle size of the amorphous silica (C) used in the present invention is 0.01 to 1 μm, preferably 0.05 to 1 μm.
To 0.8 μm, more preferably 0.1 to 0.6 μm. When the average particle size is larger than 1 μm, the fluidity of the composition becomes poor when the composition is filled in the mold, and further, the amorphous silica cannot obtain the effect of retaining moisture, and the Therefore, the composition does not extend sufficiently.

In addition, when crystalline silica is used, since the amorphous silica does not cause a pozzolanic reaction that consumes calcium hydroxide resulting from the hydration of cement, the bending strength in a saturated state is reduced. As the amorphous silica (C), for example, silica fume, micro silica, or the like is used. As the amorphous silica, a powder may be used as it is, or a slurry obtained by dispersing in water and slurry may be used.

The amorphous silica (C) is preferably used in an amount of 1 to 10 parts by weight based on 100 parts by mass of the hydraulic inorganic substance (A), the crystalline inorganic filler (B) and the amorphous silica (C).
It is added by mass, more preferably 1.5 to 7 mass parts, further preferably 2 to 6 mass parts. The reason why the amount is preferably 1 part by mass or more is that when the composition is filled in the mold, the composition is sufficiently extended and easily reaches 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 increases, the bending strength in a saturated state increases. Conversely, the reason that 10 parts by mass or less is preferable is that the dehydration property of the composition is improved, and the composition is less likely to leak from the mold when pressurized,
This is because molding is easy.

In the present invention, the purpose of adding the synthetic fiber (D) is mainly to increase the toughness of the molded product, and is not particularly limited as long as it is suitable for this purpose. For example, vinylon, polypropylene, polyethylene, polyester,
Aramid, polyamide and the like can be used, vinylon and polypropylene are preferred, and vinylon is particularly preferred. 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 preferably used in an amount of 0.1 to 4 parts by mass based on 100 parts by mass of the hydraulic inorganic substance (A), the inorganic filler (B) and the amorphous silica (C). , More preferably 0.2 to 2 parts by mass, even more preferably 0.3 to 1.5 parts by mass. When the amount is 0.1 parts by mass or more, the effect of improving the toughness of the synthetic fiber is likely to be exhibited. When the amount is 4 parts by mass or less, the dispersibility of the fiber is improved, the uniformity of the molded body is improved, and the bending strength is also improved.

The synthetic fiber (D) of the present invention preferably has a diameter of 1 μm to 1 mm, preferably 5 μm to 1 μm.
0.5 mm is more preferable, and 10 μm to 0.2 mm is particularly preferable. Further, the length is preferably 1 to 50 mm, more preferably 2 to 30 mm, and particularly preferably 3 to 20 mm. Filling properties of the composition, elongation of the composition within the mold,
The diameter is preferably 1 mm or less from the viewpoint of transferability of the mold, and the length is preferably 1 mm or more from the viewpoint of the toughness improving effect.

In the present invention, the forming water is preferably 10 to 50 parts by mass based on 100 parts by mass of the hydraulic inorganic substance (A), the crystalline inorganic filler (B) and the amorphous silica (C) in total. And more preferably kneading at a ratio of 20 to 40 parts by mass. In terms of the fluidity of the composition and the extensibility of the composition when filled in a mold, 10 parts by mass or more, also from the viewpoint of transferability of the mold and reduction of the load on the wastewater treatment of dewatered water. , 50 parts by mass or less.

In the present invention, a water reducing agent can be added in such an amount that does not cause a problem that the dehydration speed becomes slow. As the water reducing agent, those conventionally known can be used, and lignin sulfonate, oxycarboxylate,
Polyalkyl allyl sulfonate, melamine formalin resin sulfonate, aromatic polycyclic condensate sulfonate and the like can be used. 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 amount added is too large, the dewatering property of the composition becomes worse, and the composition leaks from the mold when pressurized, making it difficult to mold.

As a mixer for mixing the composition, for example, a mortar mixer, an omni mixer, an Erich mixer or the like can be used. The temperature of the composition at the start of molding is adjusted to 25 to 45 ° C, preferably 30 to 40 ° C. For example, when the temperature of the composition is less than 25 ° C in winter,
In the process of pressurized dehydration, when the composition becomes a dense structure due to dehydration and the moisture permeability decreases, the viscosity of the moisture contained in the composition is high due to the low temperature, the internal moisture movement speed is slow,
Only the composition near the filter cloth surface is dehydrated and solidified, and particularly in a thick portion, the surface opposite to the filter cloth surface becomes rough, and it is impossible to form a clean surface.

On the other hand, the temperature of the composition is 25 to 45 ° C.
When adjusted to, the viscosity of the water contained in the composition decreases,
Even if the mortar near the filter cloth surface is dehydrated to have a dense structure and the water permeability is reduced, the movement of water from the inside does not stagnate, and the movement of water from inside the filter cloth side, Uniform dehydration is performed on the opposite side, and as a result, the surface of the thick portion is also formed neatly. Further, when the temperature of the composition is higher than 45 ° C., the pot life of the composition is extremely shortened, and the production is hindered.

The method of adjusting the temperature of the composition includes a method of directly adjusting the temperature of a raw material such as a hydraulic inorganic substance, a crystalline inorganic filler, and water, and a method of contacting the composition with a mixer, a feeder, a mold, or the like. Any one of the method of adjusting the temperature of the part, the method of adjusting the temperature of the raw material chamber or the entire molding chamber, or
Alternatively, some of them may be used in combination. The composition obtained by the above method is shaped by dewatering press molding. The dehydration press is a method in which the composition is placed in a mold that can be opened and closed, and pressing and dehydration are performed at the same time. A method of pressing while pulling water 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 used in the present invention has better fluidity than conventional ones, and prevents separation of water from the composition when the composition is filled in a mold. It is not necessary to fill the composition near the end of the mold, and the composition can be spread to all corners of the mold simply by placing the composition in a lump near the center of the mold. Even if the pressing speed is as high as 1 to 10 cm / sec, molding can be performed without causing leakage from the mold.

The molded article obtained by the above method can be cured by any method, and can be any of natural curing, steam curing and underwater curing. 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, by including a crystalline inorganic filler having an average particle size of 10 μm to 2 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 composition, the dewatering is facilitated at the time of pressurization and the composition 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 composition is filled in a mold so that the amorphous silica retains water and prevents separation of water from the composition. When it is performed, it extends sufficiently, reaches every corner of the mold, and can easily obtain a molded article.

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 adding synthetic fibers, the product can have toughness. In addition, by adjusting the temperature of the composition, it is possible to reduce surface roughness in a thick portion.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described more specifically below with reference to examples and comparative examples. The raw materials used in the examples and comparative examples are as follows. (A) Hydraulic inorganic substance: ordinary Portland cement (B) Crystalline inorganic filler: crushed silica 1: crushed silica, average diameter 15 μm crushed silica 2: crushed silica, average diameter 20 μm (C) Amorphous silica: Silica fume: average diameter 0.2 μm (water-dispersed slurry, solid content 50% by weight) (D) Synthetic fiber: vinylon fiber, diameter 14 μm, length 6 mm (others): Fly ash: average diameter 15 μm Finely ground silica: Average diameter 3μm

[0027]

Examples 1-2 and Comparative Examples 1-3 Hydraulic inorganic substances, crystalline inorganic fillers, amorphous silica, synthetic fibers and water in the amounts shown in Table 1 were mixed with an omni-mixer to produce compositions. did. At this time, the temperature of the finished composition was controlled by adjusting the temperature of the raw materials. Next, this composition was 440 × 3
Placed in a lump having a diameter of about 20 cm in a mold of 30 mm, and subjected to a vacuum dehydration press for 10 seconds, in which a dehydration press molding machine is used to depressurize the water from one side at a pressing speed of 5 cm / sec and a pressure of 6.9 MPa to remove water, and A molded product having a minimum thickness of 8 mm was obtained and cured by steam curing to produce a product.

The bending strength was tested in a dry state and a saturated state. A test piece was 25 mm wide from the obtained product,
It was cut into a size of 110 mm in length. 70 of them
What was dried for 24 hours in a dryer at ℃ C to dry state,
After immersion in clear water for 24 hours, it is made saturated and the span 9
The measurement was performed by a 0 mm three-point bending test. The loading direction was from the front to the back of the product, and the crosshead speed was 1 mm / min. Regarding 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.

[0029]

[Table 1]

[0030]

According to the production method of the present invention, when the composition is filled in a mold, the composition exhibits good fluidity such that the composition flows into every corner of the mold without separation of water. In addition, dewatering press molding can be easily performed without causing leakage from the mold frame during pressurization. The product obtained by the present invention has a high bending strength and a high toughness in both a dry state and a saturated state. Also, it is possible to cleanly form thick and difficult-to-form parts. For this reason, it is possible to manufacture a product exhibiting excellent properties as a building member.

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Claims (2)

[Claims] 1. A hydraulic inorganic substance (A) having an average particle size of 10
A composition containing a crystalline inorganic filler (B) having a size of 2 μm to 2 mm, amorphous silica (C) having an average particle size of 0.01 to 1 μm, and a synthetic fiber (D) is subjected to dehydration press molding, and curing and curing. A method for producing a dewatered press molded body, wherein the temperature of the composition at the start of molding is 25 ° C. to 45 ° C. 2. The addition amounts of the hydraulic inorganic substance (A), the crystalline inorganic filler (B), the amorphous silica (C), and the synthetic fiber (D) are defined as (A), (B) and (C). (A) is 30 to 80 parts by mass and (B) is 10 to 6 parts by mass with respect to 100 parts by mass in total.
9. The composition according to claim 1, wherein 9 parts by mass, (C) is 1 to 10 parts by mass, and (D) is 0.1 to 4 parts by mass.
3. The method for producing a dewatered press-formed body according to 1.).