JPH09123134A - Composition for dehydrating press molding and manufacture of dehydrating-pressed molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dehydrating-pressed molded body easily without generating any leakage from a mold during press process. SOLUTION: This composition for dehydrating-pressed molded body comprises as principal components hydraulic inorganic substance, crystalline inorganic filler of average grain size being 10 to 2mm, amorphous silica of average grain size being 0.01 to 1μm, and synthetic fiber, and this composition is subjected to dehydrating-press molding, curing and hardening. The obtained product has high bending strength and toughness in dray and water-saturated condition, so it enables manufacture of a product which exhibits excellent properties as a building member.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composition for dewatering press molding and a method for producing a dewatering press molding.

[0002]

2. Description of the Related Art A molded body made of a hydraulic inorganic substance 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 have been conventionally 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 a cement molded body which is asbestos-free and has high strength, for example, as described in JP-A-64-64804,
Water-soluble polymer substance, two or more kinds of inorganic fillers, one of which is a spherical shape and is amorphous silica fine particles having porosity and a high specific surface area, synthetic fiber, cement, and water There is a method in which and are rocked and mixed, and the resulting mixture is put into a mold that can be opened and closed and press-molded.

[0004]

Problems to be Solved by the Invention JP-A-64-6480
In Japanese Patent Laid-Open No. 4 (1994), a molded body is manufactured using cement, fly ash, silica fume, vinylon fiber, and methyl cellulose. However, when only an amorphous substance is used as the filler in this way, although the bending strength in the saturated state increases, fine cracks occur in the molded body in the dry state and the Young's modulus decreases, There is a problem that the bending strength becomes low.

Therefore, when molding is performed using only two or more kinds of crystalline silica as the filler, the flexural strength in the dry state increases, but the flexural strength in the saturated state decreases. There was a problem of doing. Therefore, the present invention solves the conventional problems described above, and particularly provides a product having excellent strength and quality as a building member.

[0006]

Means for Solving the Problems That is, according to the first aspect of the present invention,
Is a hydraulic inorganic substance, a crystalline inorganic filler having an average particle size of 10 μm to 2 mm, amorphous silica having an average particle size of 0.01 to 1 μm, and synthetic fiber as a main component for dehydration press molding It is a composition. In addition, 2 of the present invention is such that the addition amount of the hydraulic inorganic substance, crystalline inorganic filler, amorphous silica and synthetic fiber is 100 in total of the hydraulic inorganic substance, crystalline inorganic filler and amorphous silica. 30 to 80 parts by weight, 10 to 69 parts by weight, 1 to 10 parts by weight, and 0.1 to 4 parts by weight, respectively.
It is a composition for dewatering press molding, characterized in that it is used in parts by weight.

A third aspect of the present invention is a method for producing a dehydration press-molded article, which comprises subjecting the composition of the first or second aspect of the present invention to dehydration press molding and curing and curing. Less than,
The present invention will be described in more detail. 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 amount of the hydraulic inorganic substance added is 30 to 80 parts by weight, preferably 35 to 70 parts by weight, and more preferably 40, based on 100 parts by weight of the total of the hydraulic inorganic substance, the crystalline inorganic filler and the amorphous silica.
Add ~ 60 parts by weight.

The average particle size used in the present invention is 10 μm to 2 m.
The crystalline inorganic filler of m is not particularly limited as long as it does not significantly impair the action of any constituent material used in the production method of the present invention, and examples thereof include ground silica stone, silica sand,
Examples include river sand, bentonite, mica, calcium carbonate and the like, and crushed silica stone is preferable. Also, two or more kinds of crystalline inorganic fillers may be added. If an amorphous inorganic filler is used, minute cracks are formed in the molded body when dried, and the Young's modulus and flexural strength also decrease. By the way, the dehydration press molding is divided into a stage in which the mixture is filled in the mold at the initial stage of pressing and a stage in which the mixture is filled and pressurized and dehydrated. The crystalline inorganic filler also has a function of performing sufficient dehydration when pressurized.

The average particle size of the binding inorganic filler is 10
Those having a size of μm to 2 mm, preferably 12 μm to 500 μm, and more preferably 15 μm to 100 μm are used.
The average particle diameter as used herein is a value obtained by measuring the mass median diameter using a laser diffraction type particle size distribution measuring device. If the average particle size is less than 10 μm, the tendency to retain water between the crystalline inorganic filler particles becomes strong, so dehydration at the time of pressurization is facilitated and leakage of the mixture from the mold is prevented. 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 extend sufficiently to every corner of the mold when it is filled in the mold.
Further, water is separated from the mixture, and the transferability of the mold is lowered.

The crystalline inorganic filler is a hydraulic inorganic substance, crystalline inorganic filler, and amorphous silica in total of 10
0 to 69 parts by weight, preferably 23 to 69 parts by weight
64 parts by weight, more preferably 34 to 58 parts by weight are added. When the addition amount is less than 10 parts by weight, the effect of the crystalline inorganic filler that facilitates dehydration during pressurization and prevents leakage of the mixture from the mold becomes difficult to be exhibited. When the amount added exceeds 69 parts by weight, the mixture does not sufficiently spread to every corner of the mold when the mixture is filled in the mold, and water tends to be separated from the mixture, resulting in a problem that Transferability is reduced.

The average particle size of the amorphous silica used in the present invention is 0.01 to 1 μm, preferably 0.05 to 0.8.
μm, and more preferably 0.1 to 0.6 μm. If 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 further, the effect that the amorphous silica retains the water cannot be obtained, so that the amount of the water from the mixture is reduced. The mixture does not spread well because of the separation that occurs. On the other hand, when the average grain size is 0.01 μm or less, there is a problem that the cost becomes high.

Also, when crystalline silica is used, the pozzolanic reaction for consuming calcium hydroxide, which is caused by the hydration of cement due to the hydration of cement, does not occur, so that the bending strength in a saturated state becomes low. Examples of the amorphous silica that can be used include silica fume and micro silica.

The amount of the amorphous silica is 1 to 10 parts by weight, preferably 1.5 to 7 parts by weight, based on 100 parts by weight of the hydraulic inorganic substance, the crystalline inorganic filler and the amorphous silica. Preferably 2 to 6 parts by weight is added. Addition amount is 1
When the amount is less than the weight part, 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. Moreover, since the rate of the pozzolanic reaction in which the amorphous silica consumes calcium hydroxide generated by the hydration of cement becomes slow, the bending strength in a saturated state becomes low. On the other hand, when the amount added exceeds 10 parts by weight, the dehydration property of the mixture is lowered, and the mixture leaks from the mold during pressurization, making it difficult to mold.

In the present invention, the main purpose of adding the synthetic fiber is to increase the toughness of the molded product, and it is not particularly limited 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. By adding the synthetic fiber, even if a crack is generated in the molded body, the progress thereof can be suppressed, so that the toughness is remarkably improved.

The synthetic fiber is based on 100 parts by weight of hydraulic inorganic material, inorganic filler and amorphous silica.
0.1 to 4 parts by weight, preferably 0.2 to 2 parts by weight, more preferably 0.3 to 1.5 parts by weight is added. If the addition amount is less than 0.1 part by weight, the synthetic fiber is less likely to exhibit the effect of increasing the toughness. If the amount added is more than 4 parts by weight, the dispersibility of the fibers tends to decrease, the uniformity of the molded product also decreases, and the bending strength also decreases.

As the size of the synthetic fiber of the present invention, a diameter of 1 μm to 1 mm can be used, and 5 μm to 0.5 m.
m is preferable, and 10 μm to 0.2 mm is particularly preferable. In addition, the length of 1 to 50 mm can be used, 2 to 30 m
m is preferable and 3-20 mm is especially preferable. Diameter is 1
If the length is smaller than μm or the length is larger than 50 mm, the fibers are not well dispersed and it is difficult to obtain a uniform molded body. Further, when the diameter is larger than 1 mm, the mixture does not easily spread sufficiently when it is filled in the mold. If the length is less than 1 mm, the effect of increasing toughness is unlikely to be exhibited.

In the present invention, the molding water is preferably 10 to 50 parts by weight, and more preferably 20 to 40 parts by weight, based on 100 parts by weight of the hydraulic inorganic substance, the crystalline inorganic filler and the amorphous silica.
It is preferable to knead at a ratio of parts by weight. If it is less than 10 parts by weight, the dispersibility of the composition will decrease. Further, since the fluidity is lowered, the mixture is difficult to sufficiently expand when it is filled in the mold. If it exceeds 50 parts by weight, water will be easily separated from the mixture when the mixture is filled in the mold,
The transferability of the mold is reduced. Also, since fine powder is dispersed in dehydrated water, it is necessary to treat wastewater.
If it exceeds the weight part, the load of wastewater treatment becomes very large.

In the present invention, the water-soluble polymer can be added in a very small amount so as not to cause the problem of mold leakage. As the water-soluble polymer, for example,
Examples include methyl cellulose, polyvinyl alcohol, sodium polyacrylate, polyacrylamide and the like. However, if the added amount is large, the dehydration property of the mixture becomes poor,
It leaks from the mold during pressurization, making molding difficult.

As a mixer for mixing the composition thus blended, for example, a mortar mixer, an omni mixer, an Erich mixer or the like can be used. The mixture obtained by the above method is shaped by dehydration press molding. The dewatering press is one in which the mixture is put into an openable mold to perform pressing and dewatering at the same time, and as a dewatering method, a method in which water is naturally squeezed out at the time of pressing may be used, or water may be vacuumed. It is also possible to press while pulling. At this time, a molded product having a complicated shape can be obtained by applying a predetermined shape to the mold. The composition of the present invention has excellent fluidity as compared with the conventional one, and prevents the separation of water from the mixture when the mixture is filled in the mold, so that the mixture is preliminarily near the end of the mold before pressing. It is not necessary to fill the mold until it reaches the corners of the mold by placing the mixture in a block near the center of the mold. Further, 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 body obtained by the above method may be cured by any method, and any of natural curing, steam curing and underwater curing is possible. Autoclave curing is also possible up to the temperature that synthetic fibers can withstand. The conditions for autoclave curing 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 10 μm to 2
Bending strength in a dry state is improved by containing the crystalline inorganic filler of mm. Further, since the crystalline inorganic filler has an effect of improving the dehydration 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 the amorphous silica having an average particle size of 0.01 to 1 μm, the amorphous silica retains water and prevents the separation of water from the mixture. When it is filled, it extends sufficiently, reaches all the corners of the mold, and a molded body can be easily obtained. Further, since the calcium hydroxide generated as a result of the hydration of cement reacts with the amorphous silica and the consumed pozzolanic reaction occurs, the bending strength in a saturated state can be increased.

Furthermore, by adding synthetic fibers,
The product can be made tough.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

[0025]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples. The raw materials used in Examples and Comparative Examples are as follows. Cement: Normal Portland cement Grinded silica 1: Grinded silica stone, average diameter 15 μm Grinded silica stone 2: Grinded silica stone, average diameter 20 μm Fly ash: Average diameter 15 μm Silica fume: Average diameter 0.2 μm Finely ground silica stone: Sekino silica stone finely ground product, Average diameter 3 μm Synthetic fiber: Vinylon fiber (Kuraray RM), Diameter 14 μm
m, length 4 mm

[0026]

EXAMPLES AND COMPARATIVE EXAMPLES The amounts of cement, crystalline inorganic filler and silica fume shown in Table 1 were mixed in an omni mixer for 1 minute. Then, 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 with a diameter of about 20 cm in the central portion of a 440 × 330 mm mold, and this was pressed with a dehydration press molding machine (manufactured by Atago Engineering Co.) at a pressing speed of 5 cm.
/ Sec., A pressure of 70 kg / cm ² was applied to perform vacuum dewatering press for 10 seconds to reduce water from one side to drain water, and a molded body having a thickness of 8 mm was obtained.

The molded body was aged at 60 ° C. and 95% RH for 24 hours. The bending strength was tested in a dry state and a saturated state. Width of the test piece from the obtained product is 25
mm and a length of 110 mm were cut out. Among them, those dried in a dryer at 70 ° C. for 24 hours are dried, and those soaked in fresh water for 24 hours are saturated.
The measurement was performed by a three-point bending test with a span of 90 mm. The loading direction was from the front to the back of the product, and the crosshead speed was 1 mm / min.

The Young's modulus was obtained from the slope of the load-displacement curve during the bending strength test. The water content in each of the dry state and the saturated state was determined by drying the sample after the bending strength test at 105 ° C. for 24 hours and dividing the weight difference before and after drying by the weight after drying.

[0029]

[Table 1]

[0030]

EFFECTS OF THE INVENTION By using the composition and the manufacturing method of the present invention, the fluidity is so good that the mixture flows into every corner of the mold without causing separation of water when the mixture is filled in the mold. In addition, dewatering press molding can be easily performed without leaking from the mold during pressurization. The product obtained by the present invention has high flexural strength in both a dry state and a water saturated state, and high toughness. Therefore, it is possible to manufacture a product having excellent properties as a building member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C04B 111: 20

Claims (3)

[Claims] 1. A hydraulic inorganic substance having an average particle size of 10 μm
˜2 mm crystalline inorganic filler and average particle size 0.01˜
A composition for dehydration press molding containing 1 μm of amorphous silica and synthetic fibers as main components. 2. The hydraulic inorganic substance, crystalline inorganic filler, amorphous silica and synthetic fiber are added in a total amount of 1 for the hydraulic inorganic substance, crystalline inorganic filler and amorphous silica.
30 to 80 parts by weight and 10 to 69 parts by weight, respectively, relative to 00 parts by weight
The composition for dehydration press molding according to claim 1, which is 1 part by weight, 1-10 parts by weight, or 0.1-4 parts by weight. 3. A method for producing a dehydration press-molded article, which comprises subjecting the composition according to claim 1 or 2 to dehydration press-molding and curing and curing.