JP2022109639A - Bulky agent for ceramic siding board and use thereof - Google Patents

Abstract

To provide a technique for improving bulkiness of a ceramic siding board.SOLUTION: A bulky agent used for a ceramic siding board and containing a cement and a pulp includes at least one of an organic phosphonic acid and a salt thereof. The ceramic siding board includes a cement, a pulp, and at least one of an organic phosphonic acid and a salt thereof. A manufacturing method of the ceramic siding board includes a blending step of blending at least one of an organic phosphonic acid and a salt thereof, a pulp, and a cement.SELECTED DRAWING: None

Description

The present invention relates to bulking agents for ceramic siding boards.

In recent years, in the ceramic siding board as a building material, from the viewpoint of soaring material prices, the need for environmental protection, and the effective use of resources, the thickness of the ceramic siding board has been reduced while reducing the amount of pulp used, which is important for bulkiness. is desired to be maintained.

Pulp bulking agents used in the field of papermaking include paper bulking agents containing higher alcohols and their alkylene oxide adducts (Patent Document 1), and paper bulking agents containing oils and fats or sugar alcohol-based nonionic surfactants. (Patent Document 2), a paper bulking agent containing an alkylene oxide adduct of a fatty acid (Patent Document 3), a cationic compound, an amine, an acid salt of an amine, a paper bulking agent containing an amphoteric compound (Patent Document 4 ), a polyhydric alcohol fatty acid ester paper bulking agent (Patent Document 5), and a paper bulking agent containing a compound obtained by reacting epihalohydrin with a compound obtained from an aliphatic carboxylic acid and a polyamine (Patent Document 5). 6) is known.

Patent Document 7 discloses, as a method for producing a bulky inorganic board, a method of adding alkoxysilanes to a slurry and mixing and stirring to promote foaming to include fine bubbles.

WO 98/03730 pamphlet JP-A-11-200283 JP-A-11-200284 JP-A-11-269799 JP-A-11-350380 JP-A-2000-273792 JP 2004-255618 A

The paper bulking agents described in Patent Documents 1 to 6 are added to an acidic to neutral slurry. For this reason, the inventors of the present application have found that a sufficient bulking effect cannot be obtained in ceramic siding boards whose slurry is often alkaline. Also, the slurry for ceramic siding boards has a very high concentration of calcium ions. For this reason, the inventors of the present application have found that even if a paper bulking agent that is applied to an object having a low calcium ion concentration is used in a ceramic siding board, a sufficient bulking effect cannot be obtained.

In addition, in the method described in Patent Document 7, it is necessary to control foaming during mixing and stirring, so it may be difficult to produce a ceramic siding board with stable quality, and as a result, a stable bulky effect can be obtained. The inventors of the present application have found that In addition, in the method described in Patent Document 7, water running may occur during pressure molding due to the inclusion of air bubbles, which may cause cuts in the molded material, which may impair the quality of the ceramic siding board.

Therefore, a technique capable of improving the bulkiness of ceramic siding boards has been desired.

The present invention has been made to solve the above problems, and can be implemented as the following modes.

(1) According to one aspect of the present invention, there is provided a bulking agent for ceramic siding boards. This bulking agent for ceramic siding boards is used for ceramic siding boards containing cement and pulp, and is characterized by containing at least one of an organic phosphonic acid and a salt thereof. According to the ceramic siding board bulking agent of this form, the bulkiness of the ceramic siding board can be improved.

(2) In the bulking agent for ceramic siding boards of the above aspect, the organic phosphonic acid may contain 1-hydroxyethane-1,1-diphosphonic acid. This form of bulking agent for ceramic siding boards is excellent in economic efficiency, versatility and bulkiness.

(3) According to another aspect of the invention, a ceramic siding board is provided. This ceramic siding board is characterized by containing cement, pulp, and at least one of an organic phosphonic acid and a salt thereof. According to the ceramic siding board of this form, it is excellent in bulkiness.

(4) According to another aspect of the invention, there is provided a method of manufacturing a ceramic siding board. This method for producing a ceramic siding board is characterized by including a mixing step of mixing at least one of an organic phosphonic acid and a salt thereof, pulp, and cement. According to the manufacturing method of the ceramic siding board of this form, the bulkiness of the ceramic siding board can be improved.

(5) In the method for manufacturing a ceramic siding board of the above aspect, the mixing step includes a first step of mixing a pulp slurry containing the pulp with at least one of the organic phosphonic acid and a salt thereof; and a second step of mixing the cement after the first step. According to the manufacturing method of the ceramic siding board of this form, the bulkiness of the ceramic siding board can be further improved.

(6) In the method for manufacturing a ceramic siding board according to the above aspect, the organic phosphonic acid may contain 1-hydroxyethane-1,1-diphosphonic acid. According to the manufacturing method of the ceramic siding board of this form, it is excellent in economic efficiency and versatility, and can improve the bulkiness of the ceramic siding board.

(7) In the method for manufacturing a ceramic siding board of the above aspect, in the mixing step, at least one of the organic phosphonic acid and its salt is added to phosphoric acid with respect to the solid content mass of the pulp contained in the pulp slurry. They may be mixed at a ratio of 100 mg/kg or more and 25,000 mg/kg or less in terms of converted mass. According to the manufacturing method of the ceramic siding board of this form, the bulkiness of the ceramic siding board can be further improved.

The present invention can be realized in various forms, for example, it can be realized in the form of a method for producing a bulking agent for a ceramic siding board, a building using a ceramic siding board, and the like.

A. Bulk-increasing Agent for Ceramic Siding Boards A bulk-increasing agent for ceramic siding boards according to an embodiment of the present invention is characterized by containing at least one of an organic phosphonic acid and a salt thereof. By organic phosphonic acid is meant an organic compound having at least one phosphono group in the molecule. That is, the organic phosphonic acid contains the structure of C--PO(OH) _.sub.2 in the molecule. The organic phosphonic acid salt is a compound in which the phosphono group is in the form of a salt, and the salt is not particularly limited, and examples thereof include alkali metal salts such as sodium and potassium, ammonium salts, and amine salts. The free organic phosphonic acid has at least one ionization group of a phosphono group (--PO(OH) ₂ ) in the molecule. In the following description, for convenience, organic phosphonic acids and salts thereof are also collectively referred to as "organic phosphonic acid compounds".

The number of phosphono groups per molecule of the organic phosphonic acid compound is preferably 2 or more from the viewpoint of effectively improving bulkiness by increasing the ratio of phosphono groups in the molecule. Since the ratio of phosphono groups in the molecule is large, the amount of the organic phosphonic acid compound to be added can be reduced. Moreover, the organic phosphonic acid compound preferably has a hydroxyl group from the viewpoint of solubility in water.

Examples of organic phosphonic acids include alkylidene diphosphonic acids such as 1-hydroxyethane-1,1-diphosphonic acid and 1-hydroxymethane-1,1-diphosphonic acid, aminotri(methylenephosphonic acid) and ethylenediaminetetra(methylene phosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), hexamethylenediaminetetra(methylenephosphonic acid), nitrilotris(methylenephosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid, hydroxy phosphonoacetic acid and the like. The organic phosphonic acid compound is particularly preferably 1-hydroxyethane-1,1-diphosphonic acid or a salt thereof from the viewpoint of economy and versatility. In addition, an organic phosphonic acid compound may be used individually by 1 type, and may be used in combination of 2 or more type.

The bulking agent for ceramic siding boards can be used as it is as long as the organic phosphonic acid compound is liquid, or it may be prepared by diluting it with water or the like as appropriate from the viewpoint of handleability.

The bulking agent for ceramic siding boards may be obtained by dissolving an organic phosphonic acid compound in a solvent, or by dispersing (e.g., suspending or emulsifying) an organic phosphonic acid compound in a dispersion medium. . Examples of such solvent or dispersion medium include, but are not limited to, water, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, ketones such as benzophenone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, glycerin fatty acid. Esters such as esters, alcohols such as methanol, ethanol, isopropyl alcohol, 2-butanol, lauryl alcohol, myristyl alcohol, alkaline aqueous solutions such as sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, barium hydroxide aqueous solution, monoethanolamine, Amines such as triethanolamine, dicyclohexylamine, and polyetheramine are included.

The bulk-increasing agent for ceramic siding boards of the present embodiment may contain optional components, if necessary, to the extent that the effects of the present invention are not impaired. Examples of such optional components include, but are not limited to, preservatives, antifungal agents, fungicides, dispersants, and the like. These optional components may be used singly or in combination of two or more.

From the viewpoint of improving the bulking effect, the concentration of the organic phosphonic acid compound in the bulking agent for ceramic siding boards is preferably 1% by mass or more, more preferably 10% by mass or more, and 50% by mass or more. is more preferred. In addition, the concentration of the organic phosphonic acid compound in the bulking agent for ceramic siding boards is preferably 90% by mass or less, more preferably 75% by mass or less, from the viewpoint of handleability.

The bulking agent for a ceramic siding board of the present embodiment can improve the bulkiness of the ceramic siding board by containing an organic phosphonic acid compound. Although this mechanism is not clear, as a presumed mechanism, it is thought that the organic phosphonic acid adheres to the cement and acts to improve the bulkiness of the ceramic siding board.

According to the bulking agent for a ceramic siding board of the present embodiment, a ceramic siding board having excellent bulkiness can be provided. For this reason, it can contribute to the reduction of raw material costs due to the bulkiness effect and the weight reduction of ceramic siding boards. Further, the bulking agent for a ceramic siding board of the present embodiment can be used by being mixed with other raw materials when manufacturing a ceramic siding board. For this reason, the complication of the manufacturing process of the ceramic siding board can be suppressed, so that large-scale equipment changes can be omitted, and complication of process management can be suppressed. Therefore, the bulkiness of the ceramic siding board can be easily improved.

B. Ceramic Siding Board Another aspect of the present invention is a ceramic siding board comprising cement, pulp, and at least one of the organic phosphonic acid and its salt. The ceramic siding board of this embodiment is a kind of fiber-mixed board, and is used, for example, as an exterior wall material or an interior wall material for houses and shops.

[Raw materials for ceramic siding boards]
The cement used in the present embodiment is not particularly limited, but for example, various Portland cements such as normal, early strength, super early strength, low heat and moderate heat, filler mixed with limestone powder, etc., and fine powder of blast furnace slow-cooled slag Examples include cement and environment-friendly cement manufactured using various industrial wastes as main raw materials. Cement may be used individually by 1 type, and may be used in combination of 2 or more type. Cement may also contain inorganic powder such as fly ash, calcium silicate, gypsum, calcium carbonate, blast furnace slag and silica.

The pulp of this embodiment contains natural fibers and plays a role as a reinforcing fiber in the ceramic siding board. The raw material pulp may be wood pulp or non-wood pulp. Examples of wood pulp include, but are not particularly limited to, softwood kraft pulp (NKP) and hardwood kraft pulp (LKP). Examples of non-wood pulp include, but are not limited to, kenaf, bagasse, bamboo, hemp, and straw. The pulp may be bleached pulp or unbleached unbleached pulp. Also, the pulp may be virgin pulp directly made from wood or non-wood, or may be waste paper pulp made by recovering materials already manufactured as paper or the like. In addition, pulp may be used individually by 1 type, and may be used in combination of 2 or more types.

The ceramic siding board of the present embodiment may optionally contain optional components within a range that does not impair the effects of the present invention. Examples of such optional components include, but are not particularly limited to, antifoaming agents, hydrocarbons, preservatives, antifungal agents, bactericides, antirust agents, anti-skinning agents, and the like. These optional components may be used singly or in combination of two or more.

[Manufacturing method of ceramic siding board]
The method for manufacturing the ceramic siding board of the present embodiment is not particularly limited, and various manufacturing methods such as pouring, extrusion, and papermaking can be applied. The method for producing a ceramic siding board according to the present embodiment includes a mixing step of mixing at least one of the organic phosphonic acid and its salt with pulp and cement. In the mixing step, a slurry obtained by adding the raw materials to water is mixed and stirred.

The mixing step of the present embodiment includes (i) a first step of mixing at least one of an organic phosphonic acid and a salt thereof with a pulp slurry containing pulp, and (ii) mixing cement after the first step. and a second step of performing. In the first step, a pulp slurry containing raw material pulp in water and at least one of an organic phosphonic acid and a salt thereof are mixed and stirred. In the first step the pulp is defibered. The pH of the pulp slurry is alkaline (eg pH 9-pH 14) or neutral (pH 6-8). In the second step, a pulp slurry in which at least one of an organic phosphonic acid and a salt thereof is mixed with cement is mixed and stirred. A cement mixed slurry is obtained by the second step. By including the first step and the second step in the mixing step, the bulkiness of the ceramic siding board can be further improved. In the second step, inorganic powder may be mixed with cement.

The mixing step may be, for example, a step of mixing an organic phosphonic acid compound with a cement-mixed slurry obtained by mixing cement with a pulp slurry instead of the first step and the second step. The method of mixing the organic phosphonic acid compound with the pulp slurry or cement mixed slurry is not particularly limited as long as the method disperses the organic phosphonic acid compound in the slurry. Examples thereof include a method of continuously mixing using a liquid feed pump, and a method of mixing a specified batch amount at regular intervals. The place where the organic phosphonic acid compound is mixed may be, for example, a pulper, a return line for drained water discharged during molding of a ceramic siding board, raw material dilution water, or the like. Moreover, at least one of the organic phosphonic acid and its salt may be added at a plurality of locations as necessary.

At least one of the organic phosphonic acid and its salt is mixed at a ratio of 100 mg/kg or more in terms of phosphoric acid with respect to the solid content mass of the pulp contained in the pulp slurry, from the viewpoint of improving the bulking effect. more preferably 1,000 mg/kg or more, and particularly preferably 5,000 mg/kg or more. In addition, from the viewpoint of economy, at least one of the organic phosphonic acid and its salt is used at a ratio of 25,000 mg / kg or less in terms of phosphoric acid with respect to the solid content mass of the pulp contained in the pulp slurry. They are preferably mixed, and more preferably mixed at a ratio of 20,000 mg/kg or less. For example, by mixing an organic phosphonic acid compound at a ratio of 5,000 mg/kg or more and 20,000 mg/kg or less in terms of phosphoric acid with respect to the solid content mass of the pulp contained in the pulp slurry, excellent bulkiness can be obtained. while suppressing an increase in material cost.

The preferred mass of the organic phosphonic acid compound with respect to the mass of the solid content of pulp is not limited to the case of mixing the organic phosphonic acid compound with the pulp slurry, but is the same when mixing the organic phosphonic acid compound with the cement mixed slurry or the like. be. The pulp concentration in the pulp slurry is not particularly limited, but may be, for example, 0.1 to 10% by mass.

From the viewpoint of improving bulkiness, at least one of the organic phosphonic acid and its salt is preferably mixed at a rate of 3 mg/kg or more in terms of phosphoric acid with respect to the mass of the cement mixture slurry. It is more preferable to mix at a ratio of 15 mg/kg or more. In addition, from the viewpoint of economy, it is preferable to mix at a ratio of 75 mg / kg or less in terms of phosphoric acid, and 60 mg / kg or less in terms of phosphoric acid, with respect to the mass of the cement mixed slurry. is more preferable. The cement concentration in the cement mixed slurry is not particularly limited, but may be, for example, 2 to 15% by mass.

When manufacturing a ceramic siding board by papermaking, the method further includes a papermaking step of papermaking the cement-mixed slurry obtained in the mixing step. In the paper-making process, the cement-mixed slurry is made like paper to produce a plate-like formed plate. More specifically, for example, after pouring the cement-mixed slurry onto a net, it is filtered and dewatered to produce a cement cake. The resulting cement cake is pressed, shaped, dried and hardened to produce a ceramic siding board.

In the present embodiment, there is no limitation on the elapsed time from the dispersing of the organic phosphonic acid compound in the slurry to the papermaking step. In general, the cement mixed slurry and pulp slurry after preparation are sent to the papermaking process in about 1 to 30 minutes, but regardless of the length of time elapsed after mixing the organic phosphonic acid compound, the ceramic siding board has excellent bulkiness. can be manufactured.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to the following examples. In addition, description with "%" in an example means the mass % unless there is particular limitation.

Ceramic siding boards of Examples 1 to 11 and Comparative Examples 1 to 14 were prepared as follows using Example Compounds 1 to 5 and Comparative Example Compounds 6 to 9 shown in the table below. The pH values of the pulp slurries in Examples and Comparative Examples were as shown in the following tables.

[Example 1]
Compound 1 (1-hydroxyethane-1,1-diphosphonic acid) was added to 250 g of pulp slurry containing 3.7% waste paper pulp in water so that the amount of compound 1 (1-hydroxyethane-1,1-diphosphonic acid) was 25,000 mg PO ₄ /kg in terms of phosphoric acid with respect to the raw material pulp. was added and stirred for 5 minutes. After that, 1250 g of water, 75 g of fly ash (equivalent to JIS A6201-II type) and 45 g of portland cement were added and vigorously stirred for 1 minute to obtain a cement mixed slurry. The cement mixed slurry thus obtained was subjected to No. 1 filter paper, suction filtration was performed with a filter having a diameter of 100 mm. Suction filtration was performed until the water content reached about 40%, and the cement cake of the filtration residue was recovered. The recovered cement cake was placed in a mold with a diameter of 100 mm and pressed at a pressure of 18 kgf/cm ² to mold it. After the molding was allowed to stand at 50° C. under saturated steam pressure for about 12 hours, it was treated at 160° C. under saturated steam pressure for 5 hours to cure by hydration reaction. Then, the ceramic siding board of Example 1 was obtained by drying by standing at 120° C. for 24 hours.

[Examples 2 to 10]
Ceramic siding boards of Examples 2 to 6 were obtained in the same manufacturing method as in Example 1, except that Compound 1 was contained so as to have the content shown in Table 1 below. Further, instead of compound 1, compound 2 (2-phosphonobutane-1,2,4-tricarboxylic acid), compound 3 (nitrilotris (methylene phosphonic acid)), compound 4 (N,N,N',N'-ethylenediamine Ceramic siding boards of Examples 7 to 10 were obtained in the same manner as in Example 4, except that tetrakis (methylene phosphonic acid)) and compound 5 (diethylenetriaminepenta (methylene phosphonic acid)) were used.

[Example 11]
A ceramic siding board of Example 11 was obtained in the same manner as in Example 4, except that virgin pulp was used instead of waste paper pulp.

[Comparative Example 1]
A ceramic siding board of Comparative Example 1 was obtained in the same manufacturing method as in Example 1, except that compound 1 was not added.

[Comparative Examples 2 and 3]
Ceramic siding boards of Comparative Examples 2 and 3 were obtained in the same manner as in Examples 5 and 4, except that Compound 6 (sodium ligninsulfonate) was added instead of Compound 1. Comparative Examples 2 and 3 differ from each other in the content of compound 6.

[Comparative Examples 4 and 5]
Ceramic siding boards of Comparative Examples 4 and 5 were obtained in the same manner as in Examples 5 and 4, except that Compound 7 (lauryl alcohol) was added instead of Compound 1. Comparative Examples 4 and 5 differ from each other in the content of compound 7.

[Comparative Examples 6 and 7]
Ceramic siding boards of Comparative Examples 6 and 7 were obtained in the same manner as in Examples 5 and 4, except that Compound 8 (tetrabutoxysilane) was added instead of Compound 1. Comparative Examples 6 and 7 differ from each other in the content of compound 8.

[Comparative Examples 8 and 9]
Ceramic siding boards of Comparative Examples 8 and 9 were obtained in the same manner as in Examples 5 and 4, except that Compound 9 (phosphoric acid) was added instead of Compound 1. In addition, Comparative Examples 8 and 9 differ from each other in the content of compound 9.

[Comparative Example 10]
A ceramic siding board of Comparative Example 10 was obtained in the same manufacturing method as in Comparative Example 1, except that virgin pulp was used instead of waste paper pulp.

[Comparative Examples 11 to 14]
Ceramic siding boards of Comparative Examples 11 to 14 were obtained in the same manner as in Comparative Examples 3, 5, 7 and 9, except that virgin pulp was used instead of waste paper pulp.

Using the ceramic siding boards of Examples 1 to 11 and Comparative Examples 1 to 14, each characteristic was determined according to the following method.

<Thickness of ceramic siding board>
The ceramic siding board was dried at 120° C. for 24 hours, and the thickness of the dried ceramic siding board (board thickness) was measured using a vernier caliper.

<Bulk ratio of ceramic siding boards>
The bulk ratios of Examples 1 to 10 and Comparative Examples 2 to 9 based on Comparative Example 1, and the bulk ratios of Example 11 and Comparative Examples 11 to 14 based on Comparative Example 10 were measured by the above method. Calculated using the measured board thickness. More specifically, the bulk ratio was calculated from the thicknesses of the ceramic siding boards of Examples 1 to 10 and Comparative Examples 2 to 9 when the thickness of the ceramic siding board of Comparative Example 1 was 100%. Similarly, the bulk ratios of Example 11 and Comparative Examples 11 to 14 were calculated based on Comparative Example 10.

The results obtained are shown below.

The above results revealed the following. From a comparison between Examples 1 to 6 and Comparative Example 1, the thickness of the ceramic siding board tends to increase as the content of the organic phosphonic acid compound increases, and the bulkiness of the ceramic siding board is improved. rice field.

Further, from a comparison of Examples 4 and 7 to 10, 2-phosphonobutane-1,2,4-tricarboxylic acid (compound 2), nitrilotris (methylenephosphonic acid) (compound 3), N,N,N',N Both '-ethylenediaminetetrakis(methylenephosphonic acid) (compound 4) and diethylenetriaminepenta(methylenephosphonic acid) (compound 5) have the same bulking effect as 1-hydroxyethane-1,1-diphosphonic acid (compound 1). was found to be obtained. That is, it was found that the thickness of the ceramic siding board tends to increase regardless of the type of organic phosphonic acid compound, and a bulky effect can be obtained.

Further, from a comparison between Example 4 and Example 11, it was found that the bulkiness of the ceramic siding board can be improved regardless of whether the raw material pulp is waste paper pulp or virgin pulp.

On the other hand, the sodium lignosulfonate (Compound 6) added in Comparative Examples 2, 3 and 11 is a substance generally added to cement boards as an AE water reducing agent. Substances used as AE water reducing agents, such as sodium lignosulfonate, were not found to be effective in improving the bulkiness of ceramic siding boards.

Lauryl alcohol (Compound 7) added in Comparative Examples 4, 5 and 12 is a representative substance generally added in the papermaking process as a bulking agent for paper. Substances used as bulking agents for papermaking, such as lauryl alcohol, were not found to be effective in improving the bulkiness of ceramic siding boards.

The tetrabutoxysilane (Compound 8) added in Comparative Examples 6, 7, and 13 is a known substance that provides a bulky effect by incorporating bubbles during the production of building material boards. However, since the manufacturing method of the ceramic siding board did not include the step of including bubbles, no bulky effect was observed.

The phosphoric acid (Compound 9) added in Comparative Examples 8, 9 and 14 is an inorganic acid that is sometimes used as a setting retarder for concrete. As shown in Table 2, the addition of phosphoric acid had no bulking effect.

The present invention is not limited to the above-described embodiments, and can be implemented in various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments and examples corresponding to the technical features in each form described in the Summary of the Invention are used to solve some or all of the above problems, or In order to achieve some or all of the effects, it is possible to appropriately replace or combine them. Also, if the technical features are not described as essential in this specification, they can be deleted as appropriate.

According to the bulking agent for a ceramic siding board, the ceramic siding board, and the method for producing the ceramic siding board of the present invention, a ceramic siding board having excellent bulkiness can be provided. Therefore, it can contribute to the reduction of raw material cost due to the bulky effect.

Claims (7)

A bulking agent used in ceramic siding boards containing cement and pulp,
characterized by containing at least one of an organic phosphonic acid and a salt thereof,
Bulking agent for ceramic siding boards. In the bulking agent for ceramic siding boards according to claim 1,
The organic phosphonic acid is characterized in that it contains 1-hydroxyethane-1,1-diphosphonic acid,
Bulking agent for ceramic siding boards. A ceramic siding board,
cement;
pulp;
and at least one of an organic phosphonic acid and a salt thereof,
Ceramic siding board. A method for manufacturing a ceramic siding board, comprising:
A mixing step of mixing at least one of an organic phosphonic acid and a salt thereof, pulp, and cement,
A method for manufacturing a ceramic siding board. In the method for manufacturing a ceramic siding board according to claim 4,
The mixing step includes
a first step of mixing a pulp slurry containing the pulp with at least one of the organic phosphonic acid and a salt thereof;
a second step of mixing the cement after the first step;
characterized by comprising
A method for manufacturing a ceramic siding board. In the method for manufacturing a ceramic siding board according to claim 4 or 5,
The organic phosphonic acid is characterized in that it contains 1-hydroxyethane-1,1-diphosphonic acid,
A method for manufacturing a ceramic siding board. In the method for manufacturing a ceramic siding board according to any one of claims 4 to 6,
In the mixing step, at least one of the organic phosphonic acid and a salt thereof is added in an amount of 100 mg/kg or more and 25,000 mg/kg or less in terms of phosphoric acid with respect to the solid content mass of the pulp contained in the pulp slurry. characterized by mixing in proportions,
A method for manufacturing a ceramic siding board.