JP2709757B2 - Building board manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a building board obtained by extruding a raw material composition obtained by kneading a hydraulic inorganic material as a main raw material, a fibrous material, a thickener, an aggregate and water, and curing the mixture. And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a method for producing a building board mainly composed of hydraulic inorganic material includes cement, asbestos, pulp,
2. Description of the Related Art There is known a method of manufacturing a building board in which a thickener and water are kneaded, extruded by an extruder, and the resulting molded board is cured by natural curing or autoclave curing in a curing room. In this extrusion molding method, since extrusion molding is performed at a high pressure, it is necessary that the kneaded material has appropriate fluidity.

[0003] Asbestos has excellent properties in that it imparts fluidity to the kneaded material and imparts shape-retaining properties to the molded plate and has a reinforcing effect, and is widely used in conventional extrusion molding methods. It has been. However, recently, the adverse effect of asbestos on the human body has become a problem, and there has been a strong demand for restrictions on use or prohibition of use. For this reason, the extrusion molding method using a kneaded material without adding asbestos has been studied.However, the flowability of the kneaded material is reduced by not using asbestos. Occurs.

As one countermeasure, a large amount of a thickening agent such as methylcellulose is added to impart fluidity, reduce the amount of mixed water, and impart shape retention by adding a synthetic resin or the like. Extrusion molding in which the strength is maintained by the addition of alternative fibers such as fibers has been performed. However, thickeners such as methylcellulose, synthetic resins, and substitute fibers added in this extrusion molding are all very expensive, and thus greatly affect the unit price of the resulting building board. In addition, the extrusion pressure increases with a decrease in the amount of mixed water, so that the productivity decreases. Further, the strength improvement by the substitute fiber cannot be expected so much, and when added in a large amount, the extrudability is lowered, which is not always preferable.

As another countermeasure, Japanese Patent Laid-Open No. 57-1833
No. 49 discloses that, by adding an inorganic lightweight powder having a water absorbing property, first, the extruded material is extruded in a state of high fluidity by adding a large amount of water to the kneaded material, and thereafter, the inorganic lightweight powder is added. There has been proposed a method for maintaining the shape retention of a molded article by absorbing moisture.

[0006]

However, all of the inorganic lightweight powders used in the above-mentioned prior art are hard and brittle porous materials, so that when they are actually subjected to high pressure in an extruder during extrusion molding, they are crushed. As a result, the water absorption performance of the inorganic lightweight powder decreases. For this reason, it is not possible to sufficiently absorb the moisture in the extruded molded plate,
There has been a problem that the increased amount of water causes dripping of the formed plate and the moldability (shape retention) is reduced.

[0007]

In view of the above situation,
The present inventors have conducted intensive research based on the view that vermiculite, which has been conventionally used as a lightweight aggregate, has excellent water absorption performance and also has flexibility, so that it can be applied to an extrusion molding method. As a result, the present invention has been completed.

That is, the present invention provides a method for producing a building board by extruding a raw material composition obtained by kneading a hydraulic inorganic material as a main raw material and curing the obtained formed plate. A method for manufacturing a building board, comprising adding vermiculite having a diameter of 1 mm or less.

The vermiculite used in the present invention is also referred to as expanded hillite, and is expanded to about 10 times its initial volume by sintering the hillite to release steam from the moisture between the cleavage planes of the mineral. Things
The flat crystals expand in a state where a number of flat crystals are stacked, and the flat crystals are easily separated. For this reason, although it has been conventionally known as a lightweight aggregate of hydraulic inorganic material, it was not able to be used as an aggregate of inorganic building materials requiring high strength because the material is actually too weak.

Therefore, when used in the present invention,
Vermiculite finely pulverized to a particle size of 1 mm or less is used. By adding vermiculite thus finely pulverized to a kneaded material containing a hydraulic inorganic material as a main raw material, it becomes possible to uniformly disperse the kneaded material in a kneaded material. Since it has flexibility, it is compressed without breaking, and the moisture in the vermiculite is extruded into the kneaded material. Therefore, the kneaded material is easily extruded from the extruder in a high water content state, that is, in a state of high fluidity. Furthermore, after being extruded, the vermiculite is restored to its original state by being released from the pressure that has been applied. At this time, excess moisture in the kneaded material is absorbed by vermiculite,
The water content in the kneaded material decreases.

By the action of such vermiculite, the amount of mixed water can be increased, and since the particles are fine, a bearing effect in the kneaded material works to improve extrudability. Further, dripping of the formed plate is prevented, and the shape retention is improved. Furthermore, since the amount of mixed water can be increased, the amount of fibers can be increased as well, and the strength can be improved. In addition, particle size 1
By using the finely pulverized material to a size of not more than mm, the exfoliation of the flat crystals described above can be performed well without affecting the bending strength of the finally obtained building board. Becomes

When a vermiculite having a particle size of more than 1 mm is used, when an inorganic plate obtained as a final product is subjected to a load such as a bending test, the strength is reduced such that cracks occur due to peeling of the vermiculite crystals. Is not preferred. The amount of the vermiculite added is 3 to 1 with respect to the hydraulic inorganic material such as cement.
0% by weight is added. If the amount is less than 3% by weight, the amount of water absorbed by vermiculite is small. If the amount of the mixed water is reduced to avoid this, it is not preferable because both the shape retention and the extrudability are reduced, for example, the fluidity of the kneaded material is reduced and the extrudability is reduced. 10% by weight
If the addition exceeds the above range, the dimensional stability is reduced due to the shrinkage and expansion of the vermiculite dispersed in the finally obtained building board, and the strength is reduced due to the separation of crystals, which is not preferable.

In addition to the above-described effects, vermiculite is a natural mineral and therefore has excellent heat resistance. For this reason, the extruded molded plate can be autoclaved at a high temperature, and a high-strength building board can be obtained without causing expansion and shrinkage due to heating and without generating microcracks in the autoclave curing.

In the present invention, the raw material composition containing a hydraulic inorganic material as a main raw material includes Portland cement, alumina cement, blast furnace slag cement, mixed cement,
Hydraulic inorganic materials such as gypsum and slag, vinylon, polypropylene, acrylic, glass, aramid, carbon, metal, rock wool, pulp, edenite, walathnite, sepiolite, wood fiber, cellulose fiber, etc., fly ash, Reactive aggregates such as silica fume, silica sand, diatomaceous earth, and lime, and aggregates such as charcoal, clay, and sand are added as necessary.These raw materials are used alone or in combination. A mixture obtained by mixing and kneading according to the basic composition when the inorganic plate is extruded is used. In addition, thickeners such as methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, polyethylene oxide, and polyvinyl alcohol, which have been conventionally added to improve the fluidity of the kneaded material, are also added as necessary. By adding vermiculite, the amount of these thickeners can be significantly reduced. For example, when vermiculite is not mixed, the amount of the thickener required for extrusion molding is reduced to about 1/2 or less when vermiculite is added to the hydraulic inorganic material in the above ratio. It was found that extrusion could be performed without hindrance. Further, the amount of water added when kneading these materials can be increased to about 1.1 to 1.6 times the usual amount, so that the fluidity of the kneaded material is significantly improved.

In order to manufacture a building board according to the present invention, a mixture of a fibrous material, a thickener, an aggregate and the like and vermiculite having a particle size of 1 mm or less are mixed with a hydraulic inorganic material as a main raw material, and the mixture is emptied by a mixer. After kneading, an appropriate amount of water is added to obtain a kneaded material. The kneaded material is extruded by an extruder to obtain a continuous molded plate. The mixed fine vermiculite having a particle size of 1 mm or less is uniformly dispersed in the kneaded material, and in a state where high pressure is applied in the extruder, the vermiculite is compressed without breaking because it has flexibility, so that the inside of the vermiculite is compressed. Of water is extruded into the kneaded material. For this reason, the kneaded material has a high water content state, that is, a high fluidity state, and can be easily extruded from the extruder. Furthermore, after being extruded, the pressure is released from the pressure applied so far, so that the vermiculite recovers to its original state, and at this time, it absorbs excess moisture in the kneaded material and reduces the moisture content in the kneaded material. . As a result, the amount of mixed water can be increased, and the extrudability is improved due to the effect of the bearing in the kneaded material due to the fine particles. Further, dripping of the formed plate is prevented, and the shape retention is improved.
Furthermore, since the amount of mixed water can be increased, the amount of fibers can be increased as well, and the strength can be improved.

Next, the formed board obtained is cut into a suitable length, formed by press molding or the like, and subjected to natural curing, steam curing or autoclave curing to obtain a building board. When the autoclave curing is selected as the curing method, the curing reaction of the cement can proceed in a short time, and tobermorite crystals can be generated to obtain a high-strength building board.

[0017]

The present invention will be described in more detail with reference to the following examples. <Example 1> Portland cement 65.0% by weight Fly ash 25.7 {Pulp 3.0} Polypropylene 0.5 {Methylcellulose 0.8} Vermiculite 5.0} A mixture having the above composition was kneaded with a mixer. And further 16% by weight of water were added and kneaded. The obtained kneaded material is extruded by an extruder, and has a thickness of 12 mm and a width of 470 mm.
Was obtained. The obtained continuous molded plate was cut into an appropriate length, and was autoclaved at 170 to 180 ° C. for 10 hours to obtain an inorganic plate. Example 2 Portland cement 52.5% by weight Silica sand 35.0 １．５ Pulp 1.5 ポ リ プ ロ ピ レ ン Polypropylene 0.6 メ チ ル Methylcellulose 1.0 〃 Mineral wool 4.7 〃 Vermiculite 4.7 混合 Mixture consisting of the above composition Was kneaded with a mixer, 21% by weight of water was further added, and the mixture was treated in the same manner as in Example 1 to obtain an inorganic plate.

Each of the mixtures prepared in Examples 1 and 2 has good fluidity and is easy to extrude, and the obtained inorganic plate has good shape retention without dripping. there were.

For comparison, the same procedure was performed as in Example 1 except that the vermiculite used in Example 1 was not added. Was not able to be molded.

[0020]

According to the present invention, in a method of manufacturing a building board by extrusion of a hydraulic inorganic material, a thickening agent is added by adding vermiculite having a particle size of 1 mm or less to a kneaded product of the hydraulic inorganic material. Even if the amount of addition is reduced, it is possible to improve the fluidity of the kneaded material and to perform extrusion well, and it is industrially advantageous that the extruded plate has good shape retention without drooling. Extrusion molding can be performed. Furthermore, even if the obtained molded board is cured at a high temperature by autoclave curing, it can be cured without causing cracks in the molded board, and a high-strength building board can be manufactured.

Claims (2)

(57) [Claims] 1. A method for extruding and kneading a raw material composition obtained by kneading a hydraulic inorganic material as a main raw material, curing the obtained formed plate and manufacturing a building board, wherein the raw material composition has a particle size of 1 mm or less. A method for producing a building board, characterized by adding vermiculite. 2. The method according to claim 1, wherein the vermiculite is added in an amount of 3 to 10% by weight based on the hydraulic inorganic material.
A method for manufacturing a building board according to claim 1 .