JPH0699173B2 - Reinforced cement composition for extrusion molding - Google Patents

Description

TECHNICAL FIELD The present invention has high mechanical strength by extrusion molding,
The present invention also relates to a reinforced cement composition that gives a cured product having good surface smoothness.

Conventional technology So far, as a reinforced cement composition for extrusion molding,
Reinforcing fibers such as asbestos fibers, pulp fibers, glass fibers, synthetic fibers, carbon fibers, metal fibers and molding aids such as methylcellulose are added to the basic composition of cement mixed with aggregates such as silica sand. It is known that the mixture is added and further kneaded by adding a necessary amount of water.

Each of these reinforcing fibers has a relatively long dimension of several mm to several tens of mm, and this is oriented in the extrusion direction during extrusion, reinforcing between each aggregate particle, and the extrusion direction of the matrix. Is considered to cover the lack of strength.

However, the dispersibility of pulp fibers and synthetic fibers in cement is poor, and even if they are mixed in a proportion of 2 to 3% by weight, so-called fiber balls occur and the reinforcing effect becomes insufficient,
It has the drawback of roughening the surface, and in the case of glass fiber, carbon fiber, and metal fiber, the volume shrinkage due to the setting and hardening action of cement over time causes peeling between the reinforcing fiber and the matrix. In addition to the insufficient reinforcing effect, the fibers are exposed on the surface of the molded product, and the surface smoothness is impaired.

On the other hand, asbestos fiber is easy to obtain and has good dispersibility and can be mixed in cement up to about 20% by weight, but since it is considered to be harmful to health and its use tends to be suppressed,
Although the emergence of materials that should replace this has been sought, up to now, none have been found to exhibit comparable performance.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Under the circumstances, the present invention overcomes the drawbacks of conventional reinforced cement compositions for extrusion molding, has no problems such as environmental pollution, and has superior physical properties. The present invention has been made for the purpose of providing a reinforced cement composition for extrusion molding capable of giving a cured product having the above.

Means for Solving the Problems The inventors of the present invention have conducted various studies on the reinforcement of the cement composition for extrusion molding, and as a result, the reinforcing fibers blended therein have a predetermined reinforcing effect unless they are long to a certain extent. Contrary to conventional wisdom that was thought not to be played, diameter is 0.
Based on this finding, it was found that when a very fine fibrillated cellulose having a length of 01 to 5 μm and a length of 10 to 900 μm was blended, a surprisingly large reinforcing effect was obtained and the surface smoothness was remarkably improved. The present invention has been completed.

That is, the present invention, cement 100 parts by weight, silica sand 50-1
As a reinforcing fiber, a diameter of 0.01 to 5 μm and a length of 10 to 900 are added to a base material composed of 50 parts by weight and an extrusion aid of 0.5 to 3.0 parts by weight.
A reinforced cement composition for extrusion molding, characterized in that 1 to 10% by weight of microfibrillated cellulose having a size of μm is mixed and the water content is adjusted to 30 to 80% by weight based on the total weight of the composition.

As the cement constituting the base material in 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.

Further, as the silica sand mixed as the aggregate, river sand, mountain sand, crushed sand and the like are used. This is added in an amount of 50 to 150 parts by weight, preferably 70 to 120 parts by weight, per 100 parts by weight of cement.

Next, in the composition of the present invention, it is necessary to add an extrusion aid for facilitating extrusion molding. As this extrusion aid, a cellulose derivative such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, or hydroethyl cellulose can be used. preferable. Other materials such as polyvinyl alcohol can also be used. These molding aids are mixed in a ratio of 0.5 to 3.0 parts by weight per 100 parts by weight of cement. If it is less than this, sufficient moldability cannot be obtained, and even if the amount is increased beyond this, further improvement in moldability cannot be expected.

In the composition of the present invention, the reinforcing fiber has a diameter of 0.01 to 5 μm.
It is necessary to incorporate microfibrillated cellulose having a length of m and a length of 10 to 900 μm. This is obtained, for example, by subjecting pulp fibers to severe mechanical impact to fibrillate them. This microfibrillated cellulose has a diameter of 0.01-1 μm, an average diameter of about 0.1 μm and a length of 10-40 μm.
m, diameter 0.01-1 μm, average diameter about 0.1 μm and length 7
Although those having a diameter of 00 to 800 μm are known, any of these may be used in the present invention.

This microfibrillated cellulose is blended in a ratio of 1 to 10% by weight with respect to the above-mentioned base material. If this amount is less than 1% by weight, a sufficient reinforcing effect cannot be obtained. Also 10% by weight
Even if it is added in a larger amount, the reinforcing effect is not further improved, and the molding pressure is increased, which causes a disadvantage that molding becomes difficult.

The microfibrillated cellulose blended in the present invention, unlike the conventionally used reinforcing fibers having a relatively long size, exists in a state of being uniformly dispersed in the matrix of the cured product, and during extrusion, in the matrix. It is considered to be oriented and improve the strength of the matrix. Therefore, macroscopically, the presence of fibers is not recognized, and therefore the surface smoothness of the cured product is not impaired even if it is blended in a considerably large amount.

In the present invention, the above components are essential components,
In addition, additives such as perlite, shirasu balloon, silica flour, vermiculite, etc., which are conventionally used in conventional cementation systems for extrusion molding, are blended in an amount that does not impair the required physical properties and extrusion moldability, if desired. You can also

Furthermore, in the present invention, it is necessary to set the water content to the range of 30 to 80% by weight based on the weight of the total solid content. If this amount is less than 30% by weight, the material will be clogged in the die during extrusion and smooth extrusion will not be performed. If this amount exceeds 80% by weight, it will be too soft and lose its shape retention property. It becomes impossible.

In the conventional extrusion molding cement composition, when the water content is 50% by weight or more, the shape retention property is lost, and it was not possible to mold, but in the present invention, a high water retention microfibrillated cellulose is used. 80% by weight because it is used
It has sufficient shape retention even at a water content up to.

To prepare the cement composition of the present invention, cement, silica sand, an extrusion aid and microfibrillated cellulose 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 3 to ²⁰ kg / cm ² . In this way, a molded product having a bending strength of 100 to 200 kg / cm ² and good surface smoothness can be obtained.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.
In addition, the physical-property value in each example is measured by the following method.

i) Bending strength: A molded product formed by extrusion molding a predetermined composition is allowed to stand for 1 day in a wet state, and then cured in water at 20 ° C for 27 days to be cured. About this cured product, Shimadzu Corporation Using an Autograph IS-10T manufactured by Mfg. Co., Ltd., it was measured by centralized loading with a span of 150 mm and a loading speed of 2 mm per minute.

ii) Moldability: A predetermined composition was compared by a molding pressure at the time of extrusion molding into a plate-shaped body having a cross section of 10 × 60 mm by using DE-50 type extrusion molding manufactured by Honda Iron Works Co., Ltd. The smaller the pressure, the better the moldability.

iii) Surface smoothness: The predetermined composition is extruded using a DE-50 type extruder of Honda Iron Works Co., Ltd. to produce a flat plate having a cross section of 10 × 60 mm,
The obtained molded product was cured, the surface condition was visually observed, and evaluated according to the following criteria.

XX: Remarkable roughness was recognized on the surface.

X: Considerable roughness was recognized on the surface.

Δ: Roughness was slightly recognized on the surface.

○: The surface was completely smooth.

Note: Generally, those with the following ratings are not practical.

Example 1 Portland cement [manufactured by Mitsubishi Mining Cement (Company)] 10
0 parts by weight, silica sand (Kumamoto No. 6) 100 parts by weight and extrusion aid [manufactured by Shin-Etsu Chemical Co., Ltd., trade name "Metrose" 90SH-400
[0] 2 parts by weight of a mixture containing microfibrillated cellulose A as a reinforcing fiber [made by Daicel Chemical Industries, Ltd., diameter 0.01
.About.1 .mu.m, length 10 to 40 .mu.m] at a rate of 1 to 10% by weight, and then water was added to adjust the water content to 40% by weight to obtain a reinforced cement composition. Next, this was extruded using a Honda Iron Works DE-50 type extrusion molding machine to produce a plate-shaped body having a cross section of 10 × 60 mm.

A graph showing the relationship between the amount of reinforcing fibers added and the moldability at this time is shown in FIG. 1 (A). Further, FIG. 2 (A) is a graph showing the relationship between the addition amount of the microfibers and the bending strength of the molded and cured product thus obtained.

Example 2 Microfibrillated cellulose B as a reinforcing fiber [manufactured by Daicel Chemical Industries, Ltd., diameter 0.01 to 1 μm, length 700 to 800
μm] was used to prepare a reinforced cement composition in the same manner as in Example 1.

Using this composition, a plate-like body was extrusion-molded in the same manner as in Example 1. The moldability of each is shown in FIG. 1 (B), and the bending strength is shown in FIG. 2 (B).

Comparative Example 1 As a reinforcing fiber, pulp fiber [manufactured by Hokushin Co., Ltd., diameter 10 μm
m, length 3 mm] in the same manner as in Example 1 to produce an extruded product. The moldability of the molded body thus obtained is shown in FIG. 1 (C), and the bending strength is shown in FIG. 2 (C).

Comparative Example 2 As the reinforcing fibers, the microfibrillated cellulose used in Example 1, the pulp fiber used in Comparative Example 1, the commercially available polypropylene fiber, and the commercially available carbon fiber were used,
The following table shows the amount of reinforcing fibers added and the surface smoothness of the molded product obtained in the same manner as in Example 1.

EFFECTS OF THE INVENTION The composition of the present invention is a molded product reinforced by the microscopic reinforcing effect of the matrix by the fine fibers, unlike the macroscopic reinforcing effect by the long fibers unlike the conventional reinforced cement composition for extrusion molding. Therefore, there is no decrease in strength due to the separation of fibers from the matrix due to the volume reduction due to the formation of fiber balls or the setting of cement over time, and it does not cause surface roughening due to the exposure of long fibers. . Moreover, since fine fibrillated cellulose is used as the fine fibers, good water retention can be obtained, shape retention is maintained even if the water content in the composition is increased, and extrusion molding can be facilitated. There is an advantage.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of reinforcing fibers added and the molding pressure in Examples and Comparative Examples of the present invention, and FIG. 2 is a graph showing the relationship between the amount of reinforcing fibers added and bending strength. is there.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Kawamura 2-2-1 Otemachi, Chiyoda-ku, Tokyo Sumitomo Bussan Co., Ltd. Examiner Toshiko Nakata (56) Reference JP-A-2-51460 (JP, A) JP-A-62-113741 (JP, A) JP-A-2-14860 (JP, A) JP-B-56-13671 (JP, B2)

Claims (1)

[Claims] 1. A microfibril having a diameter of 0.01 to 5 μm and a length of 10 to 900 μm as a reinforcing fiber with respect to a base material composed of 100 parts by weight of cement, 50 to 150 parts by weight of silica and 0.5 to 3.0 parts by weight of an extrusion aid. A reinforced cement composition for extrusion molding, comprising 1 to 10% by weight of activated cellulose and having a water content of 30 to 80% by weight based on the total weight of the composition.