JP2525187B2 - Manufacturing method of calcium silicate plate - Google Patents

Description

The present invention relates to a method for producing a calcium silicate board by a papermaking method.

Calcium silicate plate is nonflammable, lightweight, and excellent in workability, so that demand has been increasing in recent years.

It is known to produce calcium silicate plates. However, conventionally, it has been required that the calcium silicate plate formed by the paper-making method is crystallized by steam-curing at high temperature and high pressure in an autoclave after paper-making. When using such a method, most of them are mainly composed of tobermorite-based crystals having low heat resistance in view of reactivity when autoclave curing as well as complicated manufacturing operation,
It has been considered difficult to obtain a molded plate containing a xonotlite-based crystal as a main component, which has excellent heat resistance and needs to be steam-cured at a higher temperature and pressure.

The present applicant first mixed a spherical agglomerate composed of xonotlite needle-shaped crystals (in this specification, this agglomerate is referred to as secondary particle) and wood fiber, molded this by a papermaking method, and hot-pressed it. Proposed a method for producing calcium silicate board (Japanese Patent Publication No. 40-40896).

This method enables the production of a wood fiber board having excellent noncombustibility by using a raw material having a unique property of zonotolite crystal secondary particles, but in this method, the noncombustibility is further improved. In addition, when the amount of wood fiber is reduced, there is a problem that the strength and productivity are reduced. That is, when the amount of wood fiber is less than 20% by weight, the strength becomes insufficient, and this tendency tends to become more remarkable as the board thickness increases. Further, when the amount of fibers becomes small, the papermaking speed has to be lowered and the productivity is lowered. Moreover, the blending of wood fiber is indispensable, and it does not teach to use inorganic fiber without using it.

The present invention is an improvement of the conventional method for producing a calcium silicate plate by a papermaking method using secondary particles of calcium silicate crystals, which has good papermaking property, is lightweight, has high strength, and further has high nonflammability. An object of the present invention is to provide a method capable of producing a product with high productivity.

The present invention, in an aqueous slurry containing calcium silicate crystal secondary particles and a fibrous material, a cationic flocculant 0.05 to 1.0% by weight and anionic or nonionic flocculant 0.01 to 1.0% by weight based on the solid content of both. 1.5% by weight of total addition
The present invention relates to a method for producing a calcium silicate plate, which comprises adding the paper in an amount not exceeding the above range, forming the slurry into paper, and then performing pressure molding and then drying, or simultaneously drying the press molding.

Secondary particles of calcium silicate crystals used in the present invention,
For example, it can be produced by the method of JP-B-53-12526 and JP-A-53-146997. That is, it can be produced by heating the silicic acid raw material and the lime raw material under pressure in an autoclave with stirring to cause a hydrothermal synthesis reaction. In the present invention, the calcium silicate crystal is a xonotlite crystal,
Includes wollastonite crystals and tobermorite crystals. The calcium silicate crystals that make up the board of the present invention may be one of these crystals or a mixed system.

Silica raw materials for producing the above-mentioned calcium silicate crystals are natural amorphous silicic acid, silica sand, silica gel, silica flour (ferrosilicon dust, etc.), white carbon, diatomaceous earth, and hydrosilicofluoric acid by-produced in the wet phosphoric acid production process. Examples thereof include silica obtained by reacting with aluminum hydroxide. Examples of the lime raw material include quick lime, slaked lime, carbide slag, cement and the like. These starting materials can be used alone or in admixture of two or more.

The CaO / SiO ₂ molar ratio of the silicic acid raw material and the lime raw material is about 0.7 to 0.9 when trying to synthesize a tobermorite crystal, and 0.90 to when it is trying to synthesize a xonotlite crystal.
It is about 1.15.

Water is further added to the silicic acid raw material and the lime raw material to prepare a raw material slurry. The amount of water when preparing this raw material slurry is 5 times or more, preferably 10 to 50 times by weight, the solid content of the raw material slurry. The raw material slurry thus prepared is then subjected to a hydrothermal synthesis reaction with stirring. This reaction is usually 4 kg / cm ² or more, preferably a saturated steam pressure of 6~30kg / cm ^2, usually performed about 0.5 to 20 hours, thereby calcium silicate crystals secondary particles.

In addition, the zonotolite crystals obtained by the above hydrothermal synthesis reaction are further calcined at about 1000 ° C. without changing the shape (secondary particles) of the crystals forming the β
-It can be wollastonite.

In the present invention, an aqueous slurry containing the secondary particles and the fibers is prepared by adding a fibrous substance to the aqueous slurry of the calcium silicate crystal secondary particles. The fibrous material includes organic fibers and inorganic fibers. As the organic fibers, not only wood fibers but also synthetic fibers can be used. For example, wood pulp, waste paper pulp, knots, hemp, Cellulose fibers such as rayon and the like, and synthetic fibers such as polyamide, polyester, vinylon and polyolefin can be used. As the inorganic fibers, asbestos, rock wool, slag wool, glass fibers, silica fibers, ceramic fibers, carbon fibers, inorganic whiskers and the like can be used. These fibrous substances can be used not only in one kind but also in a suitable mixture of two or more kinds.

In the present invention, calcium silicate crystals are mainly used, and even if a small amount of a fibrous substance is mixed therein, it is possible to easily make a paper and obtain a board having high strength. Therefore, it is possible to obtain a high-strength board excellent in nonflammability by reducing the amount of organic fibers blended. Further, it is possible to obtain a board having high strength even if inorganic fibers are blended without using organic fibers. The fibrous substance is 2 to 30% by weight based on the total amount of the calcium silicate crystal secondary particles and the fibrous substance.
Therefore, the board of the present invention has excellent strength in such a calcium silicate crystal-based region, and also has good paper formability in production. A particularly preferable amount of the fibrous substance is in the range of 2 to 20% by weight, particularly 5 to 15% by weight.

The solid content concentration of the aqueous slurry containing the secondary particles of calcium silicate crystals and the wood fiber is usually 0.2 to 3% by weight.
It is preferable to adjust the degree to papermaking.

In the present invention, the aqueous slurry containing the calcium silicate crystal secondary particles and the fibrous fiber obtained above, a cationic flocculant and an anionic flocculant or a nonionic flocculant is added before papermaking. Required. By this addition, the water content of the solid content in the slurry is increased, and the paper can be efficiently produced, and the strength or the board can be obtained.

The addition amount of these aggregating agents is important for achieving the above purpose. Based on the solid content in the slurry, the amount of the cationic flocculant is about 0.05 to 1.0% by weight, the amount of the anionic flocculant or the nonionic flocculant is about 0.05 to 1.0% by weight, and the total addition amount of both exceeds about 1.5% by weight. It is better not to.

In the present invention, the effect of using such a specific aggregating agent is obtained by aggregating the secondary particles and the fibrous fiber with the cationic aggregating agent or with the anionic or nonionic aggregating agent. It is believed that this makes it possible to form stable flocs, which enhances the aqueous content of solids in the slurry. Further, regarding the addition of the aggregating agent, it is preferable to first add the cationic aggregating agent and then add the anionic aggregating agent or the nonionic aggregating agent. That is, when a specific amount of a cationic coagulant is added to the slurry, the zeta potential (electrokinetic potential) of the surface of the solid content in the slurry is increased to form a coagulum that is not decomposed even by stirring, and then a specific amount of the aggregate is formed. By adding an anionic flocculant or a specific amount of nonionic flocculant, the aggregate can be aggregated to obtain a slurry having large and stable flocs.

Further, according to the experiments conducted by the present inventors, when a cationic flocculant, an anionic flocculant, and a nonionic flocculant were used alone, the aggregation in the slurry was insufficient even if the addition amount thereof was increased. There are many leaks during papermaking (poor water quality) and poor papermaking properties.

The flocculant used in the present invention preferably has a molecular weight of about tens of thousands for the cationic flocculant, and has a molecular weight of several hundreds for the anionic flocculant and the nonionic flocculant.
Those of about 10 to 10 million are preferable. Further, the anionic coagulant preferably has an ionic strength of 1.5 meq / g or less.

Here, the ionic strength is obtained as follows.

That is, after adding a certain amount of methyl glycol chito acid (cationic reagent) to an aqueous solution of an anionic flocculant, the pH of the aqueous solution is
To 10.0 and then toluidine blue is added as an indicator. Then, the neutralization equivalent is obtained by titrating with an aqueous solution of potassium polyvinyl sulfate (anionic reagent), and the value obtained by the following equation is used as the ionic strength.

Specific examples of the cationic flocculant include polyethyleneimine, dialkylamine / epichlorohydrin polycondensate,
Examples include cationic polymer flocculants such as polyamidoamine / epichlorohydrin modified products and cationized polyacrylamide. Further, a cationic inorganic coagulant such as polyaluminum chloride, aluminum sulfate, sodium aluminate, ferrous sulfate, ferric sulfate, ferric chloride can also be used.

Specific examples of the anionic coagulant include ammonium polyacrylate, polyacrylic acid salts such as sodium polyacrylate, and acrylamide-acrylic acid copolymer.

Further, specific examples of the nonionic flocculant include polyacrylamide and polyethylene oxide.

As a papermaking machine for papermaking the slurry to which the aggregating agent is added, any of a continuous type (circle net type, long net type, short net type, etc.) and batch type (CTC method, Chapman method) can be used. . The papermaking may be performed in one step to the required thickness, or may be made in several steps and laminated to the required thickness. The paper sheet is then cut with a cutter, pressure-molded to a predetermined thickness, and dried.

Further, at this time, if pressure molding and drying are simultaneously performed by hot pressing or the like, the strength of the plate is improved, and the dry fuel cost is also reduced, which is convenient.

A preferred embodiment of the invention is a method of laminating and pressing paper sheets that have been formed into paper sheets, whereby a board having a large thickness and a uniform large bending strength can be obtained.

EFFECTS OF THE INVENTION According to the method of the present invention, there is no omission of the molding material during papermaking and the productivity is excellent due to the shorter water time, and the molded plate obtained by this method further has, for example, a bulk density of 0.6 to 0.7 g. It has a high bending strength of 100 kg / cm ² or more at about / cm ³ and is nonflammable. Further, there is a feature that a board having uniform and large strength can be manufactured even if the board thickness becomes thick.

EXAMPLES Hereinafter, more specific description will be given with reference to production examples and examples. Unless otherwise specified, "part" and "%" in each example mean "part by weight" and "% by weight", respectively.

Production Example 49 parts of quicklime and 51 parts of silica stone powder (CaO / SiO ₂ molar ratio of 1.0), which have been soaked with warm water at about 85 ° C, are prepared as raw material slurry by adjusting the amount of water to be 12 times the solid content. , And a hydrothermal synthesis reaction was performed under stirring at a pressure of 15 kg / cm ³ for 4 hours to obtain an aqueous slurry of secondary particles of xonotlite crystals.

Example 1 Water was added to 90% of secondary particles of xonotlite crystals, 8% of pulp and 2% of glass fiber to prepare a slurry having a concentration of 2%. After adding a predetermined amount of cationic flocculant and anionic flocculant to this slurry, water is further added to give a concentration of 0.6%,
The liquid volume was adjusted to 5 l. Oversize area of 32 cm using this slurry
The water content was evaluated using a tapping machine using a 32 cm, 60 mesh wire mesh. The results are shown in Table 1.

 However, each evaluation was based on the following method.

1) Removal of the molding material from the wire netting Visual inspection.

2) Sheet strength The sheet drained by the paper machine roller is pinched with fingers and lifted for evaluation.

◯: It does not break even if it is lifted and shaken.

X: The sheet is cut when lifted and shaken.

3) Water time The time from when the water starts to run out of water on the mat.

As is clear from Table 1, when the addition amount of the cationic coagulant exceeds 1.0% (relative to the solid content), the material comes out more frequently, and when the addition amount of the anionic coagulant exceeds 1.0%, the strength of the sheet is increased. Is not enough, and the total addition amount of both is 1.
It can be seen that the sheet strength becomes insufficient when the content exceeds 5%.

The same effect can be obtained by using other catechin flocculants such as polyethylene and dialkylamine epichlorohydrin polycondensate instead of "Polymaster R-607" (manufactured by Hakuto Kagaku Co., Ltd., dimethylamine epichlorohydrin polycondensate). was gotten.

Also for the anionic flocculant, "Polymaster R-623
Similar effects can be obtained by using other anionic flocculants such as ammonium polyacrylate and polyacrylate instead of "S" (manufactured by Hakuto Chemical Co., Ltd., polyacrylamide / polyacrylic acid copolymer). Was given.

Example 2 Fibers were mixed with secondary particles of xonotlite crystals at a predetermined ratio, and then water was further added to prepare a slurry having a concentration of 2.0%.

Further, a polymer flocculant was added to this slurry at a predetermined ratio.

A thickness of about 50 is obtained with a tapping machine using this slurry.
A mat having a thickness of 9 mm was prepared, and the mat was pressed under heating at 185 ° C. to obtain a molded body having a thickness of 9 mm.

 Table 2 shows the blending ratio and the physical properties of the obtained molded product.

 The aggregating agents used are the following five types.

Cationic polymaster R-607 (manufactured by Hakuto Chemical Co., Ltd.) Anionic polymaster R-623S (manufactured by Hakuto Chemical Co., Ltd.) Nonionic polymaster R-620 (manufactured by Hakuto Chemical Co., Ltd.) As is clear from Table 2, the water time is long unless the coagulant is added, and the physical properties of the resulting molded product are small.

* 1 However, the physical properties of the molded product were based on JIS A 9510 "Calcium silicate molded product".

Example 3 After mixing secondary particles of xonotlite crystals and fibers at a predetermined ratio, water was further added to prepare a slurry having a concentration of 20%, and then a cationic flocculant (Polymaster R-607) (Hakuto Kagaku ( 0.1%) and 0.1% of anionic flocculant (Polymaster R-623S) (manufactured by Hakuto Kagaku Co., Ltd.).
2% was added.

Using this slurry, a short-net paper making machine is used to make a paper sheet having a thickness of 0.7 mm, and 30 sheets of this sheet are laminated, and then pressure-molded while heating at 185 ° C. with a hot press. As a result, a 9 mm molded body was obtained.

 The compounding ratio and the physical property results are shown in Table 3.

1 Evaluation of papermaking property ◯: Both water-based and sheet strength are good, and papermaking can be carried out smoothly.

Δ: The aqueous solution was rather difficult, and the papermaking time was long.

X: Sheet strength is weak and papermaking cannot be performed.

2 Density, flexural strength and heating linear shrinkage conform to JIS A9510, provided that the heating linear shrinkage is 1000 ° C, 3
It is the value after heating for an hour.

3 Non-flammability According to Ministry of Construction Notification No. 1828 4 Cationic It was evaluated by nailing, sawing, etc., and those that did not cause cracking or corner chipping were rated as good.

Claims (6)

(57) [Claims] 1. An aqueous slurry containing secondary particles of calcium silicate crystals and a fibrous material, both of which contains 0.05 to 1.0% by weight of a cationic coagulant and 0.01 to 1.0% by weight of an anionic or nonionic coagulant with respect to the solid content. 1.5% by weight
A method for producing a calcium silicate board, characterized in that the slurry is made into a paper, and then pressure-molded and then dried, or simultaneously with the pressure-molding, after the addition in a range not exceeding the above range. 2. The method according to claim 1, wherein a cationic polymer flocculant and an anionic or nonionic polymer flocculant are combined and blended as the flocculant. 3. The production method according to claim 1, wherein the calcium silicate crystals are tobermorite crystals, xonotlite crystals and / or wollastonite crystals. 4. The method according to claim 1, wherein the fibrous substance is an organic fiber. 5. The method according to claim 1, wherein the fibrous substance is an inorganic fiber. 6. The production method according to claim 1, wherein the fibrous material is an inorganic fiber, and the sheets formed into a paper sheet are laminated and post-pressed.