JPH06157105A - Cement composition for extrusion molding - Google Patents

Abstract

PURPOSE:To provide a cement comps. for extrusion molding giving a molded body having high mechanical strength and satisfactory surface smoothness. CONSTITUTION:A basic compsn. contg. cement and fine aggregate in 2:1 to 2:3 weight ration is prepd., reinforcing fibers and mica are added to the compsn. by 2-10 pts.wt. and 3-29 pts.wt per 100 pts.wt. of the compsn., respectively, so that the total amt. is regulated to 13-30 pts.wt. and an extruding aid is further added by 0.5-3.0 pts.wt. The water content of the resulting compsn. is then regulated to 18-30wt.% based on the amt. of the basic compsn. to obtain the cement compsn. for extrusion molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement composition for extrusion molding which gives a fiber reinforced cement molded article having good extrusion moldability and having excellent surface smoothness and mechanical strength after curing.

[0002]

2. Description of the Related Art Up to now, for the purpose of increasing mechanical strength,
Reinforcing fibers such as asbestos fibers, pulp fibers, glass fibers, synthetic fibers, carbon fibers and metal fibers have been added to a basic composition composed of cement and fine aggregate.

In the case of extrusion molding, a high extrusion pressure is applied and dehydration occurs during extrusion, which makes molding difficult. Therefore, a water retention agent such as methyl cellulose is usually added (Japanese Patent Publication No. 43-7134). Gazette).

Among these reinforcing fibers, asbestos fiber is the most preferable in terms of moldability and appearance of the molded product, but asbestos has recently been found to be harmful to the human body. It is in the direction of changing to fibers. However, when the amount of fibers other than asbestos fibers is large, extrusion molding is difficult even if a water retention agent is added, and the molded product obtained after curing has a roughened surface and the appearance is impaired. .
For example, in the case of pulp fiber, which is economically most advantageous,
If the blending amount is 2% by weight or more, the surface roughening of the molded article cannot be prevented even if the water retention agent is used together.

On the other hand, it is also known to further improve the water retention of the fiber reinforced cement composition, to increase the extrusion rate, or to add mica in order to obtain a reinforcing effect without using asbestos (Japanese Patent Laid-Open Publication No. Sho. 55-3351, JP-A-5
7-61649, JP-A-61-14931).

However, even when mica is added in this way, if the amount of reinforcing fibers is large, extrusion molding becomes difficult, and it is not possible to suppress surface roughening of the molded product.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to an extrusion molding cement composition containing a relatively large amount of reinforcing fibers, which facilitates the molding, and has a high bending strength and excellent surface smoothness. It was made for the purpose of improving so as to give a product.

[0008]

The present inventors have conducted various studies to improve the physical properties of an extrusion molding cement composition containing reinforcing fibers, and as a result, the total amount of reinforcing fibers and mica has been increased. By specifying the amount and adjusting the total water content in a predetermined range, the cement composition that improves the extrusion moldability and gives a cured molded article having extremely excellent surface smoothness and mechanical strength is provided. Find that you can get
The present invention has been completed based on this finding.

That is, the present invention provides a basic composition 10 containing cement and fine aggregate in a weight ratio of 2: 1 to 2: 3.
2 to 10 parts by weight of the former, 3 to 29 parts by weight of the latter, and a total of 13 to Mix in an amount of 30 parts by weight and have a water content of 1 based on the total weight.
The present invention provides a cement composition for extrusion molding, which is adjusted to a range of 8 to 30% by weight.

As the cement constituting the basic composition of the composition of the present invention, any of commonly used Portland cement, magnesia cement, alumina cement, mixed cement and natural cement can be arbitrarily selected and used.

As fine aggregates, natural aggregates such as silica sand such as river sand and mountain sand, and synthetic aggregates from wastes are used. This basic composition is prepared by mixing cement and fine aggregate in a weight ratio of 2: 1 to 2: 3, preferably 1: 0.7 to 1: 1.

Next, in the composition of the present invention, it is necessary to add an extrusion aid in order to facilitate extrusion molding. As the extrusion aid, for example, a cellulose derivative such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose or the like is used. Other materials such as polyvinyl alcohol can also be used. These molding aids are added in an amount of 0.5 per 100 parts by weight of cement and fine aggregate.
˜3.0 parts by weight. If it is less than this range, sufficient moldability cannot be obtained, and even if the amount is increased beyond this range, further improvement in moldability cannot be expected, but the mechanical strength is lowered.

Further, as the reinforcing fiber, pulp fiber,
Although it can be arbitrarily selected from those conventionally used for mortar reinforcement such as glass fiber, synthetic fiber, carbon fiber, and metal fiber, pulp fiber and vinylon, which are easily available and inexpensive, are available. Synthetic fibers such as polypropylene and acrylic are preferred. As these fibers, those having a length in the range of 3 mm to 20 mm are usually used.

This is a total of 10 cement and fine aggregate.
It is necessary to use 2 to 10 parts by weight per 0 parts by weight. If it is less than this range, the reinforcing effect is insufficient, and if it is more than this range, the extrusion moldability is impaired, and the addition of mica powder does not improve the surface smoothness of the cured molded product.

Next, the composition of the present invention must contain mica powder in addition to the above-mentioned components. As the mica powder, one having an average particle size of 10 to 500 μm obtained by sieving or pulverizing is used.
If the one having a particle size larger than this is used, the extrusion moldability is deteriorated, and if the one having a particle size smaller than this is used, a cured molded product having a large mechanical strength cannot be provided.

This mica powder is in a proportion of 3 to 29 parts by weight with respect to a total of 100 parts by weight of cement and fine aggregate, and the total amount of fibers and mica is 13 to 30 parts by weight, preferably 16 to 30 parts by weight.
It is necessary to use an amount in the range of 22 parts by weight.
If the total amount of fibers and mica is less than this, the effect of improving the extrusion moldability of the cement composition and the strength and surface smoothness of the cured molded product obtained therefrom will be insufficient, and more than this If it is too large, the extrusion moldability becomes difficult.

The present invention includes the above-mentioned components as essential components. In addition to the above, additives conventionally used in the cement system for extrusion molding, such as perlite, shirasu balloon, silica flour, vermiculite, etc., are added. If desired, the desired physical properties and extrusion moldability can be compounded in an amount that does not impair the properties.

Further, in the present invention, it is necessary that the basic composition, that is, the amount of water added based on the total amount of cement and fine aggregate is in the range of 18 to 30% by weight. If this amount is less than 18% by weight, the material will be clogged in the die during extrusion molding, and smooth extrusion will not be carried out. If this amount exceeds 30% by weight, it will be too soft and lose its shape retention.

To prepare the cement composition of the present invention,
Cement, fine aggregate, extrusion aid, reinforcing fiber and mica powder are mixed at a predetermined ratio using, for example, a Fenshell mixer or an omni mixer, and kneaded with a kneader or the like.
Next, in order to produce a molded article using this composition, extrusion molding into a required shape using a screw extruder, then in the same manner as a normal cement molded article, underwater curing, aerial curing or high temperature Cured under high pressure to cure and then dry. At this time, the molding pressure can be about ² to 30 Kgf / cm ² . In this way, the bending strength is 100 to 380 Kgf /
A molded body having a good surface smoothness can be obtained with a surface area of about cm ² .

[0020]

EXAMPLES Next, the present invention will be described in more detail by way of examples. In addition, the physical-property value in each example is measured by the following method.

1) Flexural strength: A molded product obtained by molding a predetermined composition by extrusion molding is allowed to stand for 1 day in a wet state and then cured by curing in water at 20 ° C. for 27 days.
Using an autograph IS-10T manufactured by Shimadzu Corporation, measurement was performed by centralized loading with a span of 150 mm and a loading speed of 1 mm per minute.

2) Extrusion moldability: A predetermined composition was cross-sectioned with a DE-50 type extruder manufactured by Honda Iron Works Co., Ltd.
Extrusion pressure (Kg
f / cm ² ) and extrusion rate (cm / min).

3) Surface smoothness: A predetermined composition was extruded by using a DE-50 type extrusion molding machine manufactured by Honda Iron Works Co., Ltd. to produce a flat plate having a cross section of 12 × 60 mm, and the obtained molding was obtained. The body was cured and dried, and the table was visually evaluated.

XX: Remarkable roughness was recognized on the surface. X: Significant roughness was recognized on the surface. Δ: A slight roughness was recognized on the surface. ◯: The surface was completely smooth. The following items have a problem in practicality.

Reference Example 1 Portland cement [manufactured by Mitsubishi Materials Corporation] 50
50 parts by weight of silica sand (K-7 made by Kumamoto Silica Mining Co., Ltd.) are mixed to form a basic cement composition, and an extrusion aid [Shin-Etsu Chemical Co., Ltd., trade name Metroose 90SH]
-15000] 1 part by weight and pulp fiber [manufactured by Hokushin Co., Ltd.,
KP-3, length 3 mm] 2 parts by weight, 4 parts by weight or 6 parts by weight, respectively, and after mixing for 20 seconds using an omni mixer [OM-30 type manufactured by Chiyoda Giken Kogyo Co., Ltd.], 25 parts by weight of water Parts were added and mixed for an additional 30 seconds.

Next, this mixture was kneaded using a kneading machine [DM-100 type manufactured by Miyazaki Iron Works Co., Ltd.] and then cross-sectioned using an extrusion molding machine [DE-50 type manufactured by Honda Iron Works Co., Ltd.]. It was extrusion-molded into a 12 × 60 mm plate-shaped molded body.

The molded body thus obtained was heated to 27 ° C. at 27 ° C.
After curing in water for a day, it was dried at 105 ° C. for 24 hours.
Table 1 shows the extrusion molding pressure, surface smoothness, and bending strength for each molded product.

[0028]

[Table 1]

As is clear from this table, when the amount of pulp fiber is more than 2% by weight based on the basic composition, the surface properties are remarkably deteriorated and the extrusion moldability and the reinforcing effect are also deteriorated.

Mica powder [200-C type manufactured by Kuraray Co., Ltd., particle size 90 μm] was used for the samples of Examples 1 and 2 and Comparative Examples 1 and 2 with 2 parts by weight of pulp added.
Comparative Example 1 was added in a proportion of 15 parts by weight, 20 parts by weight, 30 parts by weight or 40 parts by weight per 100 parts by weight of the basic composition.
A plate-shaped molded body was manufactured in the same manner as in. Table 2 shows the extrusion molding pressure, the surface smoothness of the molded product, and the bending strength at that time.

[0031]

[Table 2]

As is clear from this table, the addition of mica powder markedly improves the planar smoothness and bending strength of the molded product, but the total amount of pulp fiber and mica powder is 30% by weight.
If the amount is larger than the above range, the flatness is deteriorated and the formability is deteriorated.

Reference Example 2 A polypropylene fiber [P-ZL manufactured by Daiwa Boshoku Co., Ltd., length 3 mm] was used as the reinforcing fiber, except that
A plate-shaped molded body was manufactured in exactly the same manner as in Reference Example 1. Table 3 shows the extrusion molding pressure, the surface smoothness of the molded product, and the bending strength at this time.

[0034]

[Table 3]

As described above, when the blending amount of the polypropylene fiber is 2 parts by weight or more, the surface moldability of the molded body is rapidly deteriorated.

Example 3, Comparative Examples 3 and 4 Mica powder [200-C type manufactured by Kuraray Co., Ltd., was added to the sample of Reference Example 2 containing 2 parts by weight, 3 parts by weight or 4 parts by weight of polypropylene fiber. Particle size 90 μm], 1 for each
5 parts by weight, 10 parts by weight or 5 parts by weight was added, and a plate-shaped molded body was produced in the same manner as in Reference Example 2. Table 4 shows the extrusion molding pressure, the surface smoothness of the molded product, and the bending strength at this time.

[0037]

[Table 4]

As described above, when the total amount of polypropylene fiber and mica powder is 16 parts by weight, the extrusion molding pressure, the surface smoothness of the molded product and the bending strength are excellent.

Reference Example 3 As a reinforcing fiber, vinylon fiber [RKRAY manufactured by Kuraray Co., Ltd.]
W, length 3 mm] was used in the same manner as in Reference Example 1 except that 2 to 8 parts by weight was used. Table 5 shows the extrusion molding pressure at this time and the surface smoothness and bending strength of the obtained molded product.

[0040]

[Table 5]

As described above, when the amount of vinylon fiber is 2 parts by weight or more, the surface smoothness of the molded product is poor in all cases.

Examples 4 and 5 and Comparative Example 5 15 parts by weight of the same mica powder as that used in Example 1 was added to the samples to which 2 parts by weight, 4 parts by weight or 6 parts by weight of the vinylon fiber of Reference Example 3 was added. Parts, 10 parts by weight or 5 parts by weight were added, and a plate-shaped molded body was produced in the same manner as in Reference Example 3. Table 6 shows the extrusion molding pressure and the surface smoothness and bending strength of the molded body at this time.

[0043]

[Table 6]

As described above, those having a total amount of vinylon fibers and mica powder in the range of 13 to 30 parts by weight per 100 parts by weight of the basic composition have excellent surface smoothness and bending strength.

Examples 6 to 9 and Comparative Example 6 Example 4 using vinylon fibers and mica powder in the amounts shown in Table 7
A plate-shaped molded body was manufactured in the same manner as in. Table 7 shows the extrusion molding pressure and the surface smoothness and bending strength of the molded body at this time.

[0046]

[Table 7]

As described above, when the total amount of the vinylon fiber and the mica powder is in the range of 13 to 30 parts by weight, the surface smoothness is good and the bending strength is high.

[0048]

INDUSTRIAL APPLICABILITY The composition of the present invention can give an effect molding having a good surface smoothness by accommodating fibers in the flake-like mica powder by utilizing the orientation, so that the mechanical strength and appearance can be improved. There is an advantage that a good material can be obtained. Moreover, since the mica powder can provide preferable physical properties such as high heat resistance, electric insulation, chemical resistance, and dimensional stability, it is possible to obtain a building material having various characteristics.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 16:06 Z 2102-4G 14:20 A 2102-4G 14:18) 2102-4G (72) Inventor Shimizu Ei 1-1 Mizue, Kurashiki City, Okayama Prefecture (72) Inventor Kotaro Ikeda 8-5 Ashiya-cho, Ashiya-shi, Hyogo Prefecture

Claims (5)

[Claims] 1. A reinforcing fiber together with 0.5 to 3.0 parts by weight of an extrusion aid per 100 parts by weight of a basic composition containing cement and fine aggregate in a weight ratio of 2: 1 to 2: 3. And mica in an amount of 2 to 10 parts by weight for the former, 3 to 29 parts by weight for the latter, and a total of 13 to 30 parts by weight, and a water content of 18 to 30 based on the basic composition. weight%
A cement composition for extrusion molding, which is prepared in the range of. 2. The cement composition for extrusion molding according to claim 1, wherein the cement is selected from Portland cement, magnesia cement, alumina cement, mixed cement and natural cement. 3. The cement composition for extrusion molding according to claim 1, wherein the fine aggregate is silica sand or pearlite. 4. The cement composition for extrusion molding according to claim 1, wherein the reinforcing fiber is at least one selected from pulp fiber, glass fiber, synthetic fiber, carbon fiber and metal fiber. . 5. The cement composition for extrusion molding according to claim 1, wherein the mica has an average particle size in the range of 10 to 500 mμ.