JPH0628848B2 - Extrusion molding method for inorganic plate material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an extrusion molding method for an inorganic sheet material, and more particularly to an improvement in the extrusion molding method for an inorganic sheet material containing asbestos.

[Conventional technology]

It has been well known that asbestos is very effective as a reinforcing fiber for inorganic building materials that use cement as the main raw material, but asbestos is a cause of pollution and resource use is strongly demanded to restrict or completely abolish it. However, various reinforcing properties to replace this are being sought.

Pulp fibers have been proposed as effective reinforcing fibers to replace asbestos.

However, pulp fibers have a further reinforcing effect on the cement matrix as compared with asbestos, and in the field of extrusion molding, there is a problem that the reduction of extrusion resistance is inferior to that of asbestos.

For the purpose of solving such problems, the present applicant uses pulp fibers as reinforcing fibers, and mixes clay into a kneaded product of a cement mixture for the purpose of improving extrudability,
We have proposed a method for molding an inorganic building material by extrusion molding (for example, Japanese Patent Application No. 62-221323).

[Problems of conventional technology]

However, when extrusion molding is performed by the above means, there is a problem that the bonding strength of the cement matrix is not sufficient and the water absorption of the molded body after curing is high.

[Problems to be Solved by the Invention]

In view of the above problems, the present invention increases the bonding strength of the cement matrix even though it is asbestos-free, and despite suppressing the addition amount of water to be low, a good extrusion-molded cement product having superior strength is provided. The purpose is to obtain a manufacturing method.

[Technology that has solved the problem]

That is, the extrusion molding method of the inorganic plate material of the present invention, cement, silica powder having a Blaine value of 8000 cm ² / g or more, beaten hardwood, a mixture of softwood pulp is dried to a water content of 20% or less, and further opened. A mixture consisting of dried and clay
To 100% by weight, 0.5 to 1% by weight of a high-performance water reducing agent such as lower alcohol alkylene oxide-based or anionic surfactant is added, and an extrusion aid such as methylcellulose and 27 to 30% by weight of water are added uniformly to the outside. Mixing, characterized in that the mixture is extruded, another invention, instead of a mixture of beaten hardwood, softwood pulp used in the above method, freeness beaten to 700 cc or less of hardwood, softwood pulp A dehydrated mixture having a water content of 60% or less, and then added a shortage of water to necessary kneading water to form a slurry, wherein the pulp amount is 5% by weight. Is.

[Action]

In the present invention, the compounding amounts of cement and silica stone powder themselves are the same as those conventionally known, and there is no particular point to note.

However, the silica stone powder used has a Blaine value of 8000 cm ² / g or more.

The reason for this is to increase the bonding strength of the cement matrix and also to improve the strength of the molded product in terms of material composition.

In this case, if the Blaine value is less than 8000 cm ² / g, sufficient strength improvement cannot be expected.

As the reinforcing fiber, a mixture of beaten hardwood and softwood pulp is dried to a water content of 20% or less and further opened.

The reason for limiting the water content to 20% or less is that if it exceeds 20%, the secondary aggregation of the pulp will weaken the reinforcing effect, and the screen of the crusher for opening will be easily clogged, which is inconvenient in production efficiency. is there.

Further, the one obtained by further opening the beaten pulp fiber is used to make the fiber surface fluff by opening, and to improve the entanglement with the finely powdered silica stone powder by this fluffing fiber, This is to increase the bonding strength between the matrix and the matrix.

In addition to this, pulp is beaten with a beater such as a pulper to a freeness of 700 cc or less and dehydrated to a water content of about 60% with a screw press, etc. And this may be added and kneaded.

In addition, it is effective to reduce the kneading water to make the molded product more dense, but when the water content is reduced, extrusion resistance increases and it becomes impossible to mold, so high performance of lower alcohol alkylene oxide-based or anionic surfactant etc. 0.5 to water reducing agent
Add 1% by weight.

By using this water reducing agent, even if the amount of added water is reduced, a uniform extrusion pressure can be obtained, and the capillary pores in the matrix after curing and curing can be reduced to provide a dense, high-strength, low water-absorption product.

When the amount of the high-performance water reducing agent added is 0.5 to 1% by weight, if it is more than 1% by weight, it is convenient in terms of improving the extrudability, but the effect is sufficient, and it is economical to add more. This is because the addition effect cannot be obtained if the amount is less than 0.5% by weight.

Further, the reason why the high-performance water-reducing agent is a lower alcohol alkylene oxide-based or anionic-based surfactant is because it has a good affinity with pulp fibers, and it is recommended to use one having a poor affinity with other pulp fibers. For example, extrusion molding cannot be performed even if the amount added is in the above range.

Clay imparts viscosity to the cement kneaded product and is added to reduce extrusion resistance and improve molding accuracy. If it exceeds 5% by weight, the bond strength of the matrix is adversely affected and the product strength decreases. If the amount is less than 5% by weight, the above-mentioned viscosity imparting effect is reduced.

The extrusion aid is added for the same purpose as before, but the addition of about 1% by weight may be added by adding the clay and the water reducing agent.

If the amount of water added is too large, the shape retention is deteriorated and the product after curing becomes a porous structure, resulting in a phenomenon that the strength is insufficient, and if it is too small, the extrusion resistance becomes large and extrusion molding becomes difficult. Become.

In the present invention, water is added in an amount of 25 to 30 with respect to 100% by weight of the compounding material.
The weight% is a range selected in order to make the viscosity of the cement kneaded product in the extrusion molding appropriate, but by using the above-mentioned water reducing agent, even if pulp fiber with a low water content is used, asbestos is used. Extrusion can be performed with the same pressure.

〔Example〕

 Next, an embodiment of the present invention will be described.

As a cement, ordinary Portland cement, silica powder having a Blaine value of 10000 cm ² / g, and beating as pulp fiber, a mixture of hardwood (L material) pulp and freewood (N material) pulp with a freeness of 700 or less is used. Prepare a product that has been dried to 20% or less and further opened by crushing. Also, "Tetra Guard" manufactured by Nippon Cement Co., Ltd. as a high-grade water reducing material and "Metroze" manufactured by Shin-Etsu Chemical Co., Ltd. as an extrusion aid.
90SH "was prepared, and the materials were uniformly mixed according to the formulation shown in Table 1.

The above material was extruded by an extruder with a thickness of 8 mm and a width of 100 mm, and then autoclaved under the conditions of 7 kg / cm ² × 8 hours.

This product was tested for surface condition and extrusion pressure (unit: kg / cm ² ) during extrusion molding, and the product bending strength (unit:
kg / cm ² ) and water absorption (%) were measured, and the results shown in Table 2 were obtained.

As is clear from Table 2, in the examples of the present invention, it was found that the surface condition was very good and the bending strength and the water absorption were superior to the comparative examples.

〔effect〕

As described above, according to the present invention, a cement product having excellent strength and low water absorption rate can be efficiently extruded without using asbestos.

Claims (2)

[Claims] 1. A mixture comprising cement, a mixture of cement, silica stone powder having a Blaine value of 8000 cm ² / g or more, beaten hardwood and softwood pulp, dried to a water content of 20% or less, and further opened. 0.5% to 1% by weight of a high performance water reducing agent such as a lower alcohol alkylene oxide type or anionic type surfactant, 27% to 30% by weight of water and an extrusion aid such as methylcellulose are added to 100% by weight of the product. A method for extrusion-molding an inorganic plate material, which comprises uniformly mixing and extruding the mixture. 2. A mixture of cement, silica stone powder having a Blaine value of 8000 cm ² / g or more and clay, and hardwood and softwood pulp beaten to a freeness of 700 cc or less is dehydrated to a water content of 60% or less, and then used as necessary kneading water. 0.5 to 1% by weight of a high-performance water-reducing agent such as a lower alcohol alkylene oxide-based or anion-based surface active agent is added to 100% by weight of a composition made into a slurry by adding insufficient water, and an extrusion aid such as methylcellulose. An extrusion molding method of an inorganic plate material, which comprises adding 27 to 30% by weight of water and water and uniformly mixing the mixture, and extruding the mixture.