JP2853843B2 - Extrusion molding cement composition - Google Patents

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, and in particular, to an exterior material for a building and a roof, which provide excellent surface smoothness, moldability and strength with the use of a binder equal to or less than conventional ones. The present invention relates to a cement composition for extrusion molding which is useful as a material, a flooring material and the like.

[0002]

2. Description of the Related Art Conventionally, as an exterior material, a roof material, a floor material, etc. of a building, water is added to a material obtained by mixing about 10% by weight of asbestos fiber, aggregate, etc. with cement, and kneaded. Cement boards reinforced with asbestos fibers, obtained by extrusion using a die having a desired shape, have been widely used. This asbestos fiber has extremely good dispersibility at the time of kneading, and the obtained kneaded material has good shape retention during extrusion molding.
It is also excellent in water retention. Further, the extruded product had heat resistance enough to withstand curing by a steam pressure cooker at a high temperature of 170 ° C. or higher for imparting dimensional stability and required strength to the extruded product. Thus, asbestos fibers are required in the production of extruded products, dispersibility, shape retention, water retention,
As a reinforcing fiber satisfying various properties such as heat resistance at the same time, it has been used exclusively for extrusion molding because it is unique.

However, recently, asbestos fibers have a problem of carcinogenicity which is said to be caused by their unique fiber shape. Therefore, even in the above-mentioned extruded products, no asbestos is used at all or the amount of asbestos added is minimized. Have been required to do so. As an alternative to asbestos, organic synthetic fibers were first studied, but all of them were poor in dispersibility, shape retention, water retention, and because they were organic fibers, they had poor heat resistance. Some fibers cannot be cured. Further, from the viewpoint of cost, some of the materials having high reinforcing strength are considerably expensive as compared with asbestos fibers, and there is no material which is really satisfactory.

On the other hand, pulp fiber, which is an organic natural fiber, is relatively inexpensive, is superior in dispersibility to asbestos and is superior to other organic fibers. In this method, nailing, sawing, and the like, which were difficult with conventional asbestos fiber-containing cement molded products, can be performed, and there is an advantage that attachment as a building exterior material is facilitated. For this reason, it has been attracting attention as a substitute for asbestos fiber.

On the other hand, in the extrusion molding of a cement mortar composition, high pressure is generally applied during molding, and even in the case of a cement composition containing asbestos fibers or pulp fibers,
Extrusion molding is not possible with the water retention performance of these fibers alone, because water cannot be held uniformly in the molded body, and when the molded product is discharged from the die, the water separates and binds the molded products. However, there was a problem that it could not be performed smoothly.

In order to improve the moldability, Japanese Patent Publication No.
No. 7134 proposes a method of using an organic binder in a composition for extrusion molding. This organic binder includes methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, carboxymethylhydroxyethylcellulose, polyethylene oxide, sodium polyacrylate, casein and the like. Hydroxyalkylalkylcellulose, which has excellent properties, has been widely used.

Some proposals have been made on molding compositions containing pulp fibers to which such a binder has been added. For example, Japanese Patent Publication No. 63-1276
Japanese Patent Application Laid-Open Publication No. Sho 63-163 discloses that an extrudate having the required strength can be obtained by extrusion molding a cement composition containing a pulp fiber, a primary foamed spherical resin and a binder such as methylcellulose. No. 256558 discloses an extrusion method of cement / wood pulp to which a hardening accelerator is added.

However, the pulp fibers disclosed in these prior arts use groundwood pulp obtained from softwood or hardwood or recycled paper pulp. Since groundwood pulp contains lignin as it is, which accounts for 30 to 50% by weight of the raw wood, if it is used for extrusion molding of cement / wood pulp, the lignin content causes a delay in the hardening time of the cement, and the curing time is reduced. There was such a problem.

However, if the chemical treatment for removing lignin is performed, the pulp becomes expensive, and if pulp is used in such an amount that the necessary reinforcing effect is obtained, the total cost is the amount conventionally required for using asbestos fibers. It has become higher than. In addition, wood pulp has a maximum fiber length of about 6 mm for softwoods and about 2 mm for hardwoods. Therefore, if chemical treatment is applied to the pulp or the pulp once sheeted is crushed by mechanical means, the fiber pulp becomes staple. The length became shorter and shorter, and the effect as a reinforcing fiber, especially the impact strength reinforcing effect, was inevitably reduced as compared with the asbestos fiber observed up to 25 mm. In the recycled paper pulp, although the effect of lignin is no longer delayed, the pulp contains a large amount of fiber having a short fiber length.

[0010] For this reason, if the effect of reinforcing the fiber is to be made comparable to that of asbestos, it is necessary to add a considerable amount of pulp, which not only increases the cost but also increases the amount of the necessary binder to be added. It becomes the thing of. Further, by increasing the amount of pulp added, the incombustibility of the molded body was also deteriorated. Therefore, an organic fiber-containing cement extrusion molding method which has a necessary and sufficient impact bending strength with an organic fiber addition amount as low as possible and can be molded with an organic binder having a low addition amount and can be produced at low cost. Development of has been desired.

Therefore, the present inventors have previously described Japanese Patent Application No. Hei 2-12995.
In this item, if short hair fibers obtained from cottonseed and having a maximum length of about 10 mm are used as reinforcing fibers as they are in an unrefined state (coarse linter fibers), the total amount of cement and inorganic composition such as silica stone powder is 100%. It has been proposed that the impact strength can be obtained as low as 2 to 5 parts by weight with respect to the asbestos / cement-based molded article. However, in the above-mentioned method, extrusion molding can be performed with the binder addition amount reduced as much as possible, and the required strength can be maintained. However, the fiber length of the coarse linter is too long, and the fiber tips protrude on the surface of the molded body, and the smoothness is reduced. Had the drawback of making it worse.

[0012]

As described above, in order to use short fibers as reinforcing fibers, the amount of addition must be increased to obtain the required strength, and the binder required for maintaining the shape immediately after molding is required. The amount of addition also increases. On the other hand, when thin fibers are used, the shape retention property immediately after molding of the molded article is poor, and particularly, thick hollow extrusion molding in which the wall thickness is about 10 to 15 mm and the size of the hollow part is 40 mm or more is performed. Then, the shape retention of the upper wall portion of the hollow portion was deteriorated, and there was a possibility that the molded product was sagged.

Under these circumstances, the molded article has a necessary and sufficient strength for use, for example, the addition amount of organic fibers is as small as possible, the surface state of the molded article is smooth, the impact strength of the molded article, the bending strength is large, and the article is hardly damaged during transportation. It has been desired to develop an asbestos-free extrusion-forming cement composition that satisfies various conditions such as being able to be molded with as little binder as possible, and having low production material costs.

[0014]

The present inventors have conducted intensive studies to solve these problems, and as a result, the crude linter fiber obtained from cottonseed has a maximum length in an untreated state without pulverization or purification. When the coarse linter fiber is about 10 mm, a coarse linter fiber having a length of 0.03 to 0.3 mm obtained by pulverizing the coarse linter fiber is mixed with a reinforcing fiber, and a high-viscosity hydroxyalkylalkylmethylcellulose is used as a binder. The present inventors have found that a cement composition for extrusion molding that satisfies the above-mentioned conditions can be obtained, and has reached the present invention.

More specifically, 1 to 2 parts by weight of untreated crude linter fiber is crushed to a length of 0.03 to 0.3 mm with respect to 100 parts by weight of the total amount of the cement powder and the inorganic composition. 1 to 3 parts by weight of the obtained crude linter fiber and 2% aqueous solution
An object of the present invention is to provide a cement composition for extrusion molding, which comprises adding 0.4 to 0.6 parts by weight of a hydroxyalkylalkylcellulose having a viscosity at 20 ° C. of 100,000 cps or more.

The untreated crude linter fiber obtained from the cottonseed used in the present invention usually contains 10% or less of an oil component,
This has no particular effect on the hardening of the cement,
Rather, it works as a lubricant for smooth molding, so that the required amount of binder can be reduced. The fibers generally have a thickness of 5 to 40 μm and a length of 2 to 10 mm.

The coarse linter fiber obtained by pulverizing to a length of 0.03 to 0.3 mm has a thickness of 5 to 40, similar to that before pulverization.
μm, untreated crude linter fiber is crushed, for example, by passing it through a screen having a mesh size of 0.3 to 1 mm, or sieved with a 0.3 to 0.5 mm screen or a wire mesh after the crushing, and the sieved product is crushed again. And so on.
The crusher to be applied is exemplified by a knife type mill, an impact mill, a vibration mill and the like.

The amount of the crude linter fiber added is preferably as small as possible from the viewpoint of cost. However, in order to provide impact strength comparable to that of an asbestos / cement extruded product and to obtain shape retention immediately after molding, cement powder must be added. Untreated crude linter fiber is 1 to 100 parts by weight of the total amount of the body and the inorganic composition.
It is necessary to mix and use 2 parts by weight and 1 to 3 parts by weight of a crude linter fiber obtained by grinding to a length of 0.03 to 0.3 mm.

Examples of the hydroxyalkylalkylcellulose as a binder used in combination with these crude linter fibers include hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, and hydroxyethylethylcellulose. This addition amount is preferably as small as possible in the sense of lowering the cost, but if the addition amount is extremely reduced, the molding state deteriorates, so the total amount of the cement and the inorganic composition such as silica stone powder is 100 parts by weight. On the other hand, it must be 0.4 to 0.6 parts by weight. Also. As a viscosity index corresponding to the degree of polymerization of the hydroxyalkylalkyl cellulose, it is necessary to use a 2% aqueous solution having a viscosity as high as possible in order to reduce the amount of addition. Specifically, a 2% aqueous solution having a viscosity of 100,000 cps or more measured at 20 ° C. using a JIS Ubbelohde viscometer No. 5 is used.

The cement composition of the present invention comprises a well-known cement material, aggregate, water, other additives and the like. Cement materials used here include ordinary Portland cement and alumina cement and the like. Special cement can also be used to the extent that cost is not affected. As the aggregate, silica stone, preferably silica powder having a particle size of about cement can be used. In addition to lightweight aggregates such as pearlite, permiculite and fly ash, silica sand 5-12
No. can be used as long as it does not interfere with the present invention. The amount of water to be added is not particularly limited as long as it is within a range in which extrusion molding can be performed. However, it is preferable to add 20 to 50 parts by weight to 100 parts by weight of the total amount of the inorganic composition such as cement and silica stone.

[0021]

【Example】

Examples 1-4, Comparative Examples 1-12 Tables 1-3 were based on 70 parts by weight of cement and 30 parts by weight of silica stone powder.
The crude linter fiber or pulp fiber and the binder of the type and amount shown in Table 2 were added to a 20 liter Henschel mixer, mixed at 500 rpm for 3 minutes, water was further added, and the mixture was kneaded with a 10 liter double arm kneader for 5 minutes. Extrusion was performed with an extruder manufactured by Ishikawa Tokisha Co., Ltd., and the molded state was observed and the shape retention of the molded body was measured. In addition, the molded body was heated at 45 ° C, 1
After curing under 00% humidity for 24 hours, 170 ℃, 9kg / cm ² at 8
The strength was measured for those that had been autoclaved for hours. The state of the surface was observed by touch of the hand, and these results are also shown in Tables 1 to 3.

(Details of Materials Used) Pulverized crude linter fiber: Untreated crude linter fiber was treated with Victory Mill VP-1 (trade name, manufactured by Hosokawa Micron Corporation),
Impact crushed at a speed of 1 kg / hour using a screen of 1 mm. Binder: 90SH-100,000: manufactured by Shin-Etsu Chemical Co., Ltd., hydroxypropyl methylcellulose, 2% aqueous solution has a viscosity of 100,000 cps (JIS
Measured at 20 ° C using Ubbelohde viscometer No. 5).・ 90SH-200,000: Same as before, hydroxypropyl methylcellulose, viscosity of 2% aqueous solution is 200,000 cps (as before). -90SH-30,000: hydroxypropyl methylcellulose, the viscosity of a 2% aqueous solution is 30,000 cps (as before).

(Specification of Test Method) Shape Retention and Evaluation: A molded sheet having a thickness of 10 mm, a width of 75 mm and a length of 40 cm is placed on two trees of 10 cm in height arranged at intervals of 25 cm. Measure the length of the sagging after leaving it for a minute, ・ ○ for the sagging length of 20-30mm, ○ for the sagging length of 30-40mm, ・ ・ Sagging for the sagging length of 30-40mm Those having a length of 40 mm or more were rated as Δ ×. Molding state: A molded article having a width of 75 mm and a thickness of 10 mm immediately after molding was formed without cracks, and a mark was formed. Molded product surface condition: The best surface condition of the molded product was evaluated as ‥ 100 and the worst one was evaluated as ‥ 0,
Each was represented by a bar graph. Impact strength: Measured by Charby impact strength according to JIS K-6971. Flexural strength: Measured by flexural strength according to JIS R-5201.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

EFFECTS OF THE INVENTION According to the cement composition for extrusion molding of the present invention, the amount of organic fiber added is small, the surface condition of the molded product is smooth, the impact and bending strength of the molded product are large, and the molded product is not easily damaged during transportation. It satisfies various conditions such as necessary and sufficient strength in use, molding with as little binder as possible, and low production material cost.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 28/02-28/04 C04B 16/02 C04B 24/38 B28B 3/20

Claims (1)

(57) [Claims] 1. A total amount of a cement powder and an inorganic composition of 100
1 to 2 parts by weight of an untreated crude linter fiber and 1 to 3 parts by weight of a crude linter fiber obtained by pulverizing the untreated crude linter fiber to a length of 0.03 to 0.3 mm and a 2% aqueous solution at 20 ° C. A cement composition for extrusion molding comprising 0.4 to 0.6 parts by weight of a hydroxyalkylalkylcellulose having a viscosity of 100,000 cps or more.