JP2005205879A - Inorganic board made by paper-making process and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic board made by a paper-making process which shows excellence in workability, flexibility, strength, a screw holding force and the like, and has high shock resistance and moisture release and absorption required for a moisture-conditioning building material in spite of no use of asbestos as a raw material, and to provide its manufacturing method. <P>SOLUTION: The manufacturing method of the inorganic board made by the paper-making process comprises the steps of wet-mixing a compound to obtain slurry, the compound containing 20 to 60 mass% of a matrix-forming hydraulic material, 1 to 50 mass% of an inorganic filler, 3.5 to 12 mass% of a reinforcing fiber (excluding asbestos) and 10 to 50 mass% of calcium silicate hydrate obtained by beforehand carrying out hydrothermal synthesis of a calcareous material and a siliceous material, subjecting the slurry to the paper-making process to obtain a green board, dehydrating the obtained green board under pressure, then curing and hardening it. The calcium silicate hydrate having a special particle diameter and the specific reinforcing fiber are used, and special conditions in the paper making process are employed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inorganic papermaking plate and a method for producing the same, and more specifically, although it does not use asbestos (asbestos) as a raw material, it has excellent workability, flexibility, strength, screw holding power, etc. The present invention relates to an inorganic papermaking plate having high impact resistance and moisture absorption / release performance and a method for producing the same.

At present, inorganic boards used as general building materials include, for example, cement-based, gypsum-based, and calcium silicate-based materials. These inorganic plates are usually produced by methods such as papermaking and press molding.
As raw materials for inorganic boards, cement-based, gypsum-based and calcium silicate-based materials usually use matrix forming raw materials and fiber raw materials as essential raw materials, and together with these essential raw materials, an inorganic filler for imparting necessary performance. Used together. Conventionally, asbestos has been used as a fiber raw material. Asbestos is a very suitable fiber for the production and performance of inorganic board, but it has been pointed out that its effects on health. Therefore, asbestos can be manufactured in various ways to produce inorganic board without using asbestos and obtain the required performance. Technology development has been carried out.
For example, with respect to a method for producing a fiber-reinforced inorganic plate by a papermaking method, Patent Document 1 discloses a fiber selected from the group consisting of cellulose pulp, synthetic pulp, glass fiber, PVA fiber, PAN fiber, aramid fiber, and carbon fiber. A plurality of raw plates formed by paper-making method by wet mixing of raw materials and component raw materials mainly composed of Portland cement or matrix forming powder materials mainly composed of calcareous materials and siliceous materials In the method for producing non-asbestos slate, which is formed by laminating the sheets, press-molding, and curing and curing, the moisture content of the green plate before press molding is set to 33% or more, and the decrease in the moisture content of the green plate by press molding is 10 A method for producing non-asbestos slate, characterized in that it is at least%, is disclosed.

Patent Document 2 discloses that cement is 20 to 60% by mass, calcium silicate-based lightweight hydrothermal compound obtained by hydrothermal synthesis of a calcareous raw material and a siliceous raw material in advance, and 5 to 18% by mass of reinforcing fibers. % And a filler consisting of 0 to 60% by weight, obtained by wet molding, having a bulk specific gravity of 0.5 to 1.2, a bending strength of 10 to 30 N / mm ² and a wall magnification of 2.5 or more. A featured inorganic load bearing material is disclosed.

Further, Patent Document 3 discloses that a type II anhydrous gypsum 98-60 wt% (mass%) and a mixture of short fibers 2-40 wt% (mass%) 100 parts by weight (mass part), inorganic powder 5-100 wt%. A composition comprising a gypsum hardening accelerator having an addition ratio of 0.1 to 2.5 parts by weight (parts by weight) relative to 100 parts by weight (parts by weight) and 100 parts by weight (parts by weight) of the above type II anhydrous gypsum After making the slurry at 35 ° C. and paper-molding the slurry, the slurry is pressure-molded at a pressure of 1 to 400 kg / cm ² to obtain a paper-making plate, and the paper-making plate is subjected to an atmosphere at a temperature of 0 to 15 ° C. and a humidity of 70 to 100%. Discloses a method for producing anhydrous gypsum paperboard, which is characterized by cooling and curing.

Patent Document 4 discloses that calcium silicate hydrate having an average particle size of 25 to 150 μm is obtained by previously mixing a calcareous material and a siliceous material with water and hydrothermally synthesizing 5 to 50 mass%. In addition, a bending strength of 10 N / mm ² or more is obtained by forming a concavo-convex shape on at least one surface of the front and back surfaces by wet pressing a compound containing 20 to 60% by mass of cement and 3 to 18% by mass of reinforcing fibers. An inorganic plate (Claim 1): Calcium silicate hydrate having an average particle diameter of 25 to 150 μm and having an average particle size of 25 to 150 μm obtained by previously mixing a calcareous raw material and a siliceous raw material with water and hydrothermally synthesizing them. %, Cement, 20 to 60% by mass and reinforcing fiber 3 to 18% by mass, water is added to form a slurry, and one surface or both surfaces of the green sheet obtained by dehydrating the slurry, and unevenness Have shape The laminate obtained by superposing the template stacked single or multiple bodies were pressed at a pressure of 1~25N / mm ^2, then manufacturing method characterized by curing curable (claim 5) discloses Yes.

  In recent years, with the improvement of high heat insulation technology, the airtightness of houses and other buildings has been advanced, and the indoor temperature environment and the energy saving level have been improved. On the other hand, there are a lot of harmful effects such as indoor humidification and condensation in the cold season. It can be solved by introducing a ventilation system, but it is not practical in small offices and general households. Therefore, a humidity control building material in which a humidity control function is given to an interior wall material has been proposed. For example, in Patent Document 5, the surface hardness is reduced by including a deliquescent substance in a porous molded body having a specific amount of pores having a specific gravity within a certain range and a specific gravity within a certain range. A moisture-absorbing / releasing building material is disclosed that is high, has excellent moisture-absorbing / releasing properties, and does not easily wet on the surface even when moisture is absorbed.

Japanese Patent Publication No. 8-25182 Patent Claim JP, 2001-48630, A Claims Japanese Patent Publication No. 7-35289 JP, 2003-136514, A Claims JP, 2003-286088, A Claims

  However, the method for producing non-asbestos slate disclosed in Patent Document 1 relates to a method for efficiently producing a non-asbestos slate having a large thickness without causing peeling by a papermaking method. There is no disclosure of a method for producing non-asbestos slate with excellent moisture absorption / release performance. Further, the non-asbestos slate produced by this method has high density and high strength, but does not necessarily have sufficient flexibility, impact resistance and moisture absorption / release performance. Patent Document 2 does not disclose any method for producing an inorganic plate excellent in impact resistance and moisture absorption / release performance, and is produced by using the raw materials and methods disclosed in Patent Document 2. The obtained inorganic load-bearing face material has high density and high strength, but does not necessarily have sufficient flexibility, impact resistance, and moisture absorption / release performance. Furthermore, the method for producing an anhydrous gypsum board disclosed in Patent Document 3 does not disclose any method for producing an anhydrous gypsum board excellent in impact resistance and moisture absorption / release performance. Patent Document 4 relates to an inorganic plate having a deep concavo-convex shape and a method for producing the same, and does not disclose any method for producing an inorganic plate excellent in impact resistance and moisture absorption / release performance. Furthermore, Patent Document 5 does not disclose anything about producing a humidity-control building material by a papermaking method.

  In addition, structural plywood is also frequently used as a load bearing wall. Although this structural plywood is made of wood, it is a multi-layer structure formed by bonding and has poor moisture permeability and air permeability. Therefore, a large amount of dew condensation occurs on the inner side of the load bearing wall in the cold season, that is, on the heat insulating layer, which leads to corrosion of the material over a long period of time.

Furthermore, high impact resistance performance is required for inorganic plates used as general building materials. In particular, for example, a material constructed as a wall material is often subjected to a single high impact load or a relatively low repeated impact load. Therefore, it is necessary to impart high impact resistance to the inorganic board used as a general building material.
In general, when the apparent density of a product is increased, the product becomes rigid and the strength against static load (hereinafter simply referred to as strength) is increased, but the flexibility is poor and the impact resistance tends to be inferior. Conversely, if the apparent density of the product is lowered, flexibility can be imparted, but the strength tends to be lowered. Conversely, if the apparent density of the product is lowered, flexibility can be imparted, but the strength tends to be lowered.
Recently, building materials are required to have excellent moisture absorption / release performance as well as excellent mechanical properties such as strength, screw retention, and impact resistance.

  Therefore, the object of the present invention is excellent in workability, flexibility, strength, screw holding power, etc., while not using asbestos as a raw material, and also has high impact resistance performance and moisture absorption / release performance as a humidity control building material. An object of the present invention is to provide an inorganic papermaking plate and a method for producing the same.

  In order to obtain a lightweight and high-strength inorganic board without using asbestos, the present inventors have used as raw materials matrix-forming hydratable raw materials, fillers, reinforcing fibers (excluding asbestos), and calcareous raw materials in advance. And it has been found that it is important to use calcium silicate hydrate obtained by hydrothermal synthesis of siliceous raw materials, and has already been filed as Patent Document 2. Based on the above raw materials, as a result of various researches for improving impact resistance and imparting moisture absorption and desorption performance without reducing strength, using a papermaking method with excellent manufacturing efficiency, When manufacturing an inorganic board using the raw material, the apparent density and bending strength of the manufactured inorganic board are important for the blending conditions of the raw material and the pressure during pressure dehydration of the green board obtained by papermaking. However, with regard to impact resistance and moisture absorption and desorption performance, not only the mixing conditions of raw materials and the pressure conditions when pressure dewatering the green plate obtained by papermaking, but also the process conditions in the papermaking process, and pressure dehydration It has been found that the ratio between the apparent density of the green board before and the apparent density of the green board after pressure dehydration has a great influence, and the present invention has been completed.

That is, the method for producing an inorganic papermaking plate of the present invention comprises 20 to 60% by mass of a hydrated raw material for forming a matrix; 1 to 50% by mass of an inorganic filler; 3.5 to 12% by mass of reinforcing fibers (excluding asbestos); A slurry containing 10 to 50% by mass of calcium silicate hydrate obtained by hydrothermal synthesis of a calcareous raw material and a siliceous raw material in advance is wet mixed to obtain a slurry, and the resulting slurry is made. In the manufacturing method of the inorganic paper-making board which obtains a raw board by pressurizing and dehydrating the obtained raw board, and curing and hardening, the average particle diameter of the said calcium silicate hydrate is the range of 30 micrometers-100 micrometers The reinforcing fiber has a freeness of 3 to 11% by weight and a fiber length of 6.0 to 0.2 mm and a fiber diameter of 20 to 50 μm in a Canadian standard freeness range of 150 to 450 ml. The thin film on the endless felt in the paper making process has a dehydration rate in the range of 5 to 30% / second and is wound around a making roll. When the moisture content of the thin film is 100 to 180%, the apparent density of the green plate after separation from the making roll is set within the range of 0.35 to 0.65 g / cm ³ , and the green plate is subjected to pressure dehydration. The apparent density of the green plate after pressure dehydration is 1.3 to 2.0 times the apparent density of the green plate before pressure dehydration.

  Moreover, the manufacturing method of the inorganic papermaking board of this invention is characterized by the papermaking method being a round net-type papermaking method.

Furthermore, the inorganic papermaking plate manufactured by the method for manufacturing an inorganic papermaking plate is characterized in that the bending strength of the inorganic papermaking plate is 10 N / mm ² or more.

  Moreover, the inorganic papermaking board manufactured by the manufacturing method of the said inorganic papermaking board is characterized by the screw retention strength per 1 mm thickness of the said inorganic papermaking board being 20 N or more.

  Furthermore, the inorganic papermaking plate produced by the method for producing an inorganic papermaking plate is characterized in that impact energy per 1 mm thickness of the inorganic papermaking plate is 2.0 J or more.

Moreover, the inorganic papermaking board manufactured by the manufacturing method of the said inorganic papermaking board WHEREIN: The moisture absorption-and-release amount between 23 degreeC-75% RH and 23 degreeC-53% RH of the said inorganic papermaking board is 30 g / m < ² > or more. It is characterized by being.

  According to the present invention, despite not using asbestos as a raw material, it has excellent workability, flexibility, strength, screw holding power, etc., and has high impact resistance and moisture absorption / release performance as a humidity control building material. An inorganic papermaking plate and a method for producing the same are provided.

Hereinafter, the present invention will be described in more detail.
Since the papermaking method is excellent in production efficiency, it has been widely used as a method for producing an inorganic board. In the conventional inorganic papermaking board, the most common reinforcing fiber was asbestos. Asbestos has good dispersibility when it is mixed with each raw material to be described later with water and has a positive zeta potential, so that the hydrating raw material for forming a matrix constituting the matrix is particularly Portland cement. In the case of such a cement, since the adhesion with the cement matrix is good, it has been easy to improve the impact resistance by increasing the amount of asbestos in the conventional inorganic papermaking board. In addition, even when other fibers are used in combination with asbestos, the dispersibility of the fibers when mixing the raw materials and the adhesion to the cement matrix do not decrease so much. By using it together, it was easy to improve the impact resistance of the inorganic papermaking plate. However, asbestos has been pointed out to affect health, so it has become necessary to use fibers that replace asbestos. In the case of asbestos substitute fiber, if the blending ratio is increased, not only uniform dispersion becomes extremely difficult in the raw material mixing, but also the problem that the aesthetic appearance of the product surface is impaired, and organic fiber is used as asbestos substitute fiber. Since it is often used, the incombustibility and fire resistance of the product may be lowered, and the range in which the impact resistance can be improved by increasing the blending ratio of the reinforcing fibers is limited. Furthermore, if the adhesion between the fiber raw material and the cement matrix and the bonding strength of the material structure are not sufficient, high impact resistance performance cannot be obtained, but the zeta potential of wood pulp, which is a typical asbestos substitute fiber, is negative. The adhesion to the cement matrix is inferior to that of asbestos. In addition, increasing the apparent density of the inorganic papermaking board can increase its strength, but if the raw material design increases the apparent density, the inorganic papermaking board becomes rigid and loses its flexibility, so the impact resistance is not necessarily improved. is not. Further, increasing the apparent density of the inorganic papermaking plate means that the voids of the inorganic papermaking plate are reduced. The so-called moisture conditioning building materials that are currently generally provided are those that have moisture absorption and desorption performance by having a certain gap, so that they are mostly porous material structures and apparent density is also Since it is a small or ceramic material processed at a high temperature, it is actually inferior in terms of strength and impact resistance. A method of adding a large amount of calcium silicate hydrate having a specific average particle diameter as in the present invention is also in its category, but by itself, the apparent density of the resulting inorganic papermaking sheet becomes too low, and high strength and resistance Can not get impact. Therefore, despite the fact that no asbestos is used as a raw material, an inorganic papermaking plate having excellent workability, flexibility, strength, screw holding power, etc., as well as high impact resistance and moisture absorbing / releasing performance as a humidity control building material. To manufacture
(1) Predetermined blending ratio of hydrated raw material for matrix formation, filler, reinforcing fiber (excluding asbestos) and calcium silicate hydrate obtained by hydrothermal synthesis of calcareous raw material and siliceous raw material in advance as raw materials To use in;
(2) In the paper making process, forming a green plate with a predetermined apparent density by controlling the water content and dewatering rate of the green film (thin film);
(3) The apparent density of the green plate after pressure dehydration is set within a predetermined magnification range of the apparent density of the green plate before pressure dehydration.
It is important to satisfy both of these.

(Hydratable raw material for matrix formation)
The matrix-forming hydratable raw material used in the present invention may be either hydraulic or pneumatic, and is not particularly limited. However, hydraulic cement is suitable because of its high strength development ability. For example, ordinary Portland cement And high strength cement, blast furnace cement, low heat cement, eco cement and the like. Examples of the air-cement cement include gypsum-based materials such as hemihydrate gypsum and type II anhydrous gypsum. When a gypsum-based material is used, a predetermined amount of a curing retarder (citric acid, phthalic acid, tartaric acid, etc.) or a curing accelerator (alkali metal sulfate such as sodium sulfate) can be added as necessary. The specific surface area of the matrix-forming water-dispersible material in the case of hydraulic cement, 2500~5000cm ² / g, is preferably in the range of 3000~4000cm ² / g, when the air-hardening cement, 4000~80000cm ² / g Preferably, it exists in the range of 4500-6500 cm < ² > / g.

(Inorganic filler)
The inorganic filler used in the present invention is not particularly limited as long as it is generally used for an inorganic board, but for example, a filler for improving heat resistance such as mica and wollastonite, dihydrate gypsum and carbonic acid. Examples thereof include fillers for improving fire resistance such as calcium, fillers for preventing cracking such as silica, and porazone substances such as ferrosilicon dust and fly ash. These can be used in combination of two or more.

(Reinforcing fiber)
Reinforcing fibers used in the present invention include, for example, natural fibers such as wood pulp and various hemp, glass fibers, rock wool, ceramic wool, inorganic fibers such as carbon fibers, artificial pulp, polyvinyl alcohol, polypropylene, polyethylene, polyester, Examples include synthetic fibers such as acrylic and rayon. Among these, from the viewpoint of further improving the bending strength and impact resistance performance, it is preferable to use cellulosic fibers such as wood pulp as the main component of the reinforcing fibers.

  In addition, the freeness of natural fiber is in the range of 150 to 450 ml, preferably 150 to 350 ml in terms of Canadian standard freeness (hereinafter referred to as CSF) defined in JIS P8121. The CSF can be adjusted by beating a reinforcing fiber, such as wood pulp, with a refiner or the like wet. The beating treatment increases the branching of the fibers, so-called fibrillation, and as a result, it is possible to improve adhesion and flexibility with the matrix formed by hydration of the hydratable raw material for matrix formation. Here, when the CSF is 450 ml or less, sufficient adhesion between the reinforcing fibers and the matrix is achieved, good dispersion of the reinforcing fibers can be obtained, and high strength can be imparted to the product (inorganic papermaking board). it can. In addition, by increasing the CSF to 150 ml or more, the drainage of the slurry is increased, dehydration unevenness at the time of pressure dehydration, blistering, tearing, etc. are prevented, and good flexibility and consequently impact resistance performance is imparted to the product. Can do.

  The fiber length of the inorganic fiber and the synthetic fiber is 6.0 to 0.2 mm, preferably 4.0 to 0.5 mm, and the fiber diameter is 20 to 50 μm, preferably 20 to 40 μm. Is within. By prescribing the sizes of the inorganic fibers and the synthetic fibers in this way, there is an effect that sufficient strength can be obtained as a composite material while maintaining good drainage suitable for manufacturing by the papermaking method. .

(Calcium silicate hydrate)
The calcium silicate hydrate used in the present invention can be produced by mixing a calcareous raw material and a siliceous raw material together with water and hydrothermal synthesis under high temperature and high pressure.
Examples of the calcareous raw material include quick lime and slaked lime, and examples of the siliceous raw material include quartzite, diatomaceous earth, silica fume and the like, and particularly preferred is quartzite.
The synthesis of calcium silicate hydrate can be performed, for example, as follows. The calcareous raw material and the siliceous raw material are, for example, a blending ratio (CaO / SiO ₂ molar ratio) of 0.5 to 1.5, preferably 0.5 to 1.2, and a mass ratio of 5 to this mixture. ~ 20 times, preferably 7-16 times water is added, mixed and dispersed to form a raw slurry, and the raw material slurry is stirred at a temperature of 150 to 230 ° C, preferably 170 to 210 ° C, Hydrothermal synthesis is carried out for 1 to 20 hours, preferably 3 to 12 hours. In this way, calcium silicate hydrate is obtained as, for example, tobermorite, zonotrite and the like.

  The average particle diameter of the calcium silicate hydrate used in the present invention is in the range of 30 μm to 100 μm, preferably 50 μm to 90 μm. By prescribing the average particle size of calcium silicate hydrate in this way, there is an effect that it is possible to obtain sufficient strength as a composite material while maintaining good drainage suitable for production by a papermaking method. Played.

  In addition, the said average particle diameter can be adjusted with the particle size of a siliceous raw material, the ratio of the water used, the degree of stirring in a pressure vessel, etc. For example, the particle size of the siliceous material is 80 μm or less, preferably 60 μm or less, and the amount of water used is 7 to 16 times the mass ratio of the mixture of the calcareous material and the siliceous material, and is provided in the pressure vessel. By setting the peripheral speed of the obtained stirring rotary blade to 100 to 200 m / min, the average particle diameter of the obtained calcium silicate hydrate can be adjusted in the range of 30 μm to 100 μm as described above. In addition, the average particle diameter of the calcium silicate hydrate prescribed | regulated by this invention is calculated | required with the particle size distribution measuring apparatus by the laser diffraction scattering method.

(Mixing ratio)
The various raw materials are 20 to 60% by mass, preferably 30 to 60% by mass, and 1 to 50% by mass, and preferably 1 to 30% by mass of an inorganic filler, as a mass ratio with respect to the resulting anhydrous papermaking plate. It is preferable to blend so as to be 3% by mass, 3-12% by mass of reinforcing fibers, preferably 3-10% by mass, and 10-50% by mass, preferably 15-40% by mass of calcium silicate hydrate. The reinforcing fiber has a freeness of 3.5 to 11% by mass, preferably 4 to 8% by mass, and a fiber length of 6.0 to 0.2 mm. The inorganic fiber and / or synthetic fiber in the range of 20 to 50 μm in diameter, and 0.5 to 5% by mass, preferably 0.5 to 3% by mass, of natural fiber and inorganic fiber and / or synthetic fiber It mix | blends so that a total amount may become in the said range.

(Manufacture of anhydrous papermaking board)
In the inorganic papermaking plate of the present invention, the above-mentioned various materials are preferably blended at the above-mentioned blending ratio, and 7 to 30 times (mass ratio) of the various materials, preferably 10 to 20 times as much water is added thereto, and wet. It can be manufactured by mixing and preparing a slurry, and making the obtained slurry to obtain a green plate, dehydrating the obtained green plate under pressure, and curing and curing. However, in the method for producing the inorganic papermaking sheet of the present invention, the dehydration rate of the thin film on the endless felt in the papermaking process is 5 to 30% / second, preferably 5 to 15% / second, and the making roll The apparent density of the green plate after being separated from the making roll by setting the moisture content of the thin film when wound to 100 to 180%, preferably 110 to 160% in the range of 0.35 to 0.65 g / cm ³ Then, the obtained green plate is dehydrated under pressure, and the apparent density of the green plate after pressure dehydration is 1.3 to 2.0 of the apparent density of the green plate before pressure dehydration. It is important that the condition is within the double range (condition 2).

  In the paper making process, when the dehydration rate of the thin film on the endless felt is less than 5% / second, the apparent density of the green plate obtained becomes high, and when the film is wound on the making roll due to its high water content. It is not preferable because the resistance of squeezing becomes high and a good quality raw board cannot be obtained. Further, when the dehydration rate exceeds 30% / second, the raw plate moisture content becomes too low, the target raw plate apparent density cannot be obtained, and the adhesion between the layers is remarkably lost to obtain a product. This is not preferable because it cannot be performed. Further, if the moisture content of the thin film when wound on a making roll is less than 100%, the apparent density of the resulting product becomes high, and a desired moisture absorption / release performance cannot be obtained, and the moisture content is 180%. If it is super, resistance of squeezing when winding on a making roll becomes high, and a good quality green plate cannot be obtained, which is not preferable.

  In addition, as the papermaking method referred to in the present invention, any papermaking method known in the art can be applied, and examples thereof include a round net type papermaking method, a long net type papermaking method, and a flow-on type papermaking method. For example, in the round net making method, the raw slurry is made with a wire mesh cylinder to form a green film (thin film), and the resulting green film is transferred to an endless felt, dehydrated on the endless felt, and applied to a making roll. The green sheet (raw board) is obtained by winding up to a thickness of 1 mm and separating from the making roll when the thickness reaches a predetermined thickness. In addition, the flow-on type papermaking method supplies raw slurry directly onto the endless felt, dehydrates it on the endless felt to form a green film (thin film), winds it up to a predetermined thickness on a making roll, When the thickness is reached, the green sheet (raw board) is obtained by separating from the making roll. Among them, the round netting method is preferable from the viewpoint that the production efficiency is high, the production of thin objects is possible, and the two-dimensional orientation of the fibers is good, so that the reinforcing performance can be sufficiently exhibited. In the present invention, a sheet-like molded product before pressure dehydration obtained after paper making of a slurry is defined as “raw plate”.

In the above condition (1), the apparent density means that the obtained material is dried to an absolutely dry state (a state dried to a constant weight at 105 ° C.), and the mass (g) after drying is expressed as its volume (cm ^It can be calculated by the method of dividing by ³ ). The apparent density of the green board is preferably 0.4 to 0.6 g / cm ³ . In condition (1), if the apparent density is less than 0.35 g / cm ³ , an inorganic papermaking sheet satisfying both flexibility and impact resistance performance cannot be obtained. Further, when the apparent density is more than 0.65 g / cm ³ , the apparent density of the inorganic papermaking plate obtained by dehydrating the raw plate, curing and curing it becomes too high, and it is suitable for moisture absorption / release performance. This is not preferable because the porosity is lost.

  In addition, in the condition (2), when the apparent density after pressure dehydration of the green plate is less than 1.3 times the apparent density of the green plate before pressure dehydration, Densification is not sufficiently achieved, and the desired strength of the product cannot be obtained, and the desired impact resistance performance cannot be obtained because the bonding strength of the material structure is weak. On the other hand, if it exceeds 2.0 times, the material density becomes too high and high bending strength can be obtained, but it does not become a suitable porosity as a humidity control building material, and the moisture absorption and desorption performance is significantly reduced. In addition, the flexibility of the product is impaired, and the impact resistance performance is lowered. Moreover, it takes a lot of time for dehydration under pressure, leading to a decrease in work efficiency and causing water cracking, wrinkles and the like.

The pressure plate can be dehydrated using a pressure dehydration apparatus such as a known press machine. The pressure dehydration conditions (pressure increase speed, holding pressure, holding time, etc.) of the green plate are 1.3 to 2.0 times the apparent density of the green plate after pressure dehydration. It is necessary to set it within the range. As a method for determining the conditions for pressure dehydration, for example, prior to actual production, a raw slurry is dehydrated at 5 to 30% / second by an aspiration dehydration test simulating papermaking, and an apparent density is 0.35 to 0.00. A green plate of 65 g / cm ³ was prepared and subjected to a pressure dehydration test. The apparent density of the green plate after pressure dehydration was 1.3 to 2.0 times the apparent density of the green plate before pressure dehydration. The pressure dehydration conditions may be determined so as to be within the range. Therefore, the condition of the pressurized dehydration include, but are not limited for a particular range, the holding pressure is generally 5 to 30 N / mm ^2, holding pressure (N / mm ²⁾ and retention time (in seconds) The product is approximately 1000 to 40000 N / mm ² · sec.

  In the present invention, the curing and curing method is not particularly limited. For example, known means such as natural curing, wet curing, and cooling curing can be applied.

  The material thickness of the inorganic building materials currently on the market is 3 to 4 mm as a lower limit for thin materials, and those below that are not yet practical products. Further, when it is thin, the handling property is remarkably lowered and it is easy to break. However, the product (inorganic papermaking plate) obtained by the method of the present invention can be further reduced to a thickness of, for example, about 2 mm by satisfying the above conditions (1) and (2), and is high as described above. Since it has impact resistance, cracks due to handling can be significantly reduced. The upper limit value of the product thickness is not particularly limited, but is preferably about 15 mm for the round net type papermaking method, and about 50 mm for the long net type papermaking method. This thickness can be appropriately determined by adjusting the thickness of the green plate. In addition, the thickness which can express impact resistance best is 6-12 mm.

  The inorganic papermaking plate of the present invention obtained as described above has an impact resistance energy of 2.0 J or more per 1 mm thickness of the inorganic papermaking plate. The impact energy per 1 mm thickness of the inorganic papermaking board referred to in the present invention is the maximum energy (J) that gives a predetermined impact force to the surface of the inorganic papermaking board and the inorganic papermaking board is not broken (penetrated). means. At that time, the support for the inorganic papermaking board is made of wood or the like used as a general building material, and is attached with support at two sides at a predetermined interval, and then, for example, a steel ball (eg eggplant type, ball) at the center of the inorganic papermaking board It means a value obtained by measuring the maximum energy at which the inorganic papermaking board is not destroyed, and dividing it by the thickness of the inorganic papermaking board. More specifically, the impact energy is calculated by applying an inorganic papermaking board (size: 500 mm x 500 mm) on a wooden base (size: 50 mm square x length of 500 mm) arranged in parallel at an interval of 455 mm between the centers. And place it so that the base material is vertical, and stick it with nails (iron round nails N45). The nailing interval at this time may be within the general construction condition range, but may be about 150 mm. Further, the edge distance of nailing is 22.5 mm in the present invention. It is placed on a horizontal floor and a 1 kg steel ball (eg eggplant type, sphere type) is dropped from a predetermined height toward the center of the inorganic papermaking plate. As a result, the maximum height at which the steel balls are not supported due to penetration of the steel balls or significant breakage in the inorganic papermaking plate is measured in 1 cm increments, along with the thickness of the inorganic papermaking plate, The impact energy (J) per 1 mm thickness is calculated.

In the inorganic papermaking plate of the present invention, the moisture absorption and desorption amount between 23 ° C.-75% RH and 23 ° C.-53% RH is 30 g / m ² or more. The temperature / humidity conditions are based on moisture absorption / release performance measurement (humidity response method: moisture absorption / release performance test in medium humidity range) described in JIS A 1470.

Furthermore, the inorganic papermaking plate of the present invention has a high bending strength, that is, a bending strength of 10 N / mm ² or more. Moreover, the cementitious papermaking board of the present invention has an excellent screw holding power, that is, a screw holding power of 20 N or more per 1 mm of material thickness of the inorganic papermaking board. Here, the bending strength referred to in the present invention means a value measured according to JIS A 1408. The screw holding force is a countersunk screw specified in JIS B 1112 “Cross-Hole Wood Screw” 4 and 2. Screw a wood screw with a nominal diameter of 4.1 mm and a length of 38 mm into an air-dried material. The value obtained by the method of measuring the maximum tensile load when the wood screw is pulled out with the material fixed.

Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples.
(Examples 1-7, Comparative Examples 1-9, Reference Examples 10-11)
Materials used:
(1) Calcium silicate hydrate: Type Tobermorite (slurry, solid content = 10% by mass)
(2) Ordinary Portland cement: Taiheiyo Cement, specific surface area 3300 cm ² / g
(3) Calcium carbonate: TM-1 No. (4), manufactured by Yuesu Mining Co., Ltd. (4) Wood pulp: fiber length 3.5 mm, fiber diameter 30 μm
(5) Polyvinyl alcohol fiber: fiber length 4.0 mm, fiber diameter 27 μm

In the blending ratios shown in Tables 1 to 3 below, various materials are blended, and water is added and mixed therewith to obtain a slurry having a concentration of about 10% by mass. I got a raw board. The obtained green plate was pressure dehydrated with a press machine at a predetermined pressure, and then cured at a temperature of 60 ° C. for 15 hours and cured to obtain various papermaking plates. The apparent density, bending strength, impact energy when dropping the steel ball, screw holding force, and moisture absorption / release between 23 ° C.-75% RH and 23 ° C.-53% RH were measured. A result is combined with Tables 1-3 and shown. In addition, the average particle size of calcium silicate hydrate, CSF of wood pulp, dehydration rate of thin film on endless felt, moisture content of thin film when wound on making roll, apparent density of green board before pressure dehydration Tables 1 to 3 also show the apparent density after pressure dehydrating the green plate and the thickness of the papermaking plate.
The apparent density of the papermaking plate is a value measured according to JIS A 5430.

  The calcium silicate plate of Reference Example 10 is a JIS A5430 standard product, and the volcanic glassy composite plate of Reference Example 11 is a JIS A5440 standard product.

  The cementitious papermaking board obtained by the method for producing an inorganic papermaking board according to the present invention is excellent in workability, flexibility, strength, screw holding power, etc., and has high impact resistance and absorption as a humidity control building material. It has moisture-releasing performance and can be suitably used as a general building material, and further as a moisture-conditioning building material for various applications.

Claims (6)

Hydrothermal synthesis of a hydrated raw material for matrix formation 20 to 60% by mass; an inorganic filler 1 to 50% by mass; a reinforcing fiber (excluding asbestos) 3.5 to 12% by mass; and a calcareous raw material and a siliceous raw material in advance A mixture containing 10 to 50% by mass of calcium silicate hydrate obtained in this way is wet-mixed to obtain a slurry, and a sheet is obtained to obtain a green plate. In the manufacturing method of the inorganic papermaking board which consists of curing by curing after dehydrating under pressure, the average particle diameter of the calcium silicate hydrate is in the range of 30 μm to 100 μm, and the reinforcing fiber has a freeness. Is a Canadian standard freeness of 3 to 11% by mass of natural fibers in the range of 150 to 450 ml, fiber length of 6.0 to 0.2 mm, and inorganic fibers and / or synthetic fibers in the range of fiber diameters of 20 to 50 μm. It is comprised from 0.5 to 5% by mass, the dehydration rate of the thin film on the endless felt in the paper making process is within the range of 5 to 30% / second, and the moisture content of the thin film when wound on the making roll is 100 to The apparent density of the green plate after being separated from the making roll by setting it to 180% is within the range of 0.35 to 0.65 g / cm ³ , the green plate is pressure dehydrated, and the green plate after pressure dehydration A method for producing an inorganic papermaking board, characterized in that the apparent density is within a range of 1.3 to 2.0 times the apparent density of the green board before pressure dehydration.   The manufacturing method of the inorganic papermaking board of Claim 1 whose papermaking method is a round net-type papermaking method. An inorganic papermaking plate obtained by the method for producing an inorganic papermaking plate according to claim 1, wherein the inorganic papermaking plate has a bending strength of 10 N / mm ² or more.   An inorganic papermaking plate obtained by the method for producing an inorganic papermaking plate according to claim 1 or 2, wherein a screw holding force per 1 mm thickness of the inorganic papermaking plate is 20 N or more. .   An inorganic papermaking board obtained by the method for producing an inorganic papermaking board according to claim 1 or 2, wherein an impact energy per 1 mm thickness of the inorganic papermaking board is 2.0 J or more. Paper board. An inorganic papermaking plate obtained by the method for producing an inorganic papermaking plate according to claim 1 or 2, wherein the moisture absorption and desorption amount of the inorganic papermaking plate is between 23 ° C-75% RH and 23 ° C-53% RH. Is an inorganic paper-making board, characterized in that it is 30 g / m ² or more.