JP2000119058A - Production of lightweight calcium silicate board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightweight calcium silicate board improved in interlaminar mechanical strength through diminishing voids due to excess water and reducing entrained air by compounding a stock slurry containing a siliceous stock, calcareous stock and reinforcing fiber with an addition stock comprising cement, aluminum compound stock, anhydrous gypsum stock in specified proportions followed by subjecting the resultant slurry to papermaking process to afford a green sheet which, in turn, is put to hydrothermal synthesis. SOLUTION: This lightweight calcium silicate board is obtained by the following process: a slurry containing a total of 100 pts.wt. of the above stocks is compounded with 10-100 pts.wt. of the above-mentioned addition stock; wherein part of the stocks is compounded with the addition stock to effect formation of ettringite in the resultant slurry; the slurry is held at 25-50 deg.C for 10-60 min until it is subjected to papermaking process; by the way, ettringite is made from cement, aluminum compound stock, anhydrous gypsum stock and water, being shown by the molecular formula: 3CaO.Al2O3.3CaSO4.32H2O, being left in the form of needle crystal, after filtration, on the thin film resulting from the papermaking process; these thin films are laminated together into a green sheet which is improved in adhesion owing to crystal entanglement interlaminarly; the green sheet is subsequently put to hydrothermal synthesis to effect ettringite crystal decomposition, thereby contributing to the lightweightness of the objective calcium silicate board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lightweight calcium silicate plate which is lightweight, has good adhesion between layers, and is excellent in workability.

[0002]

2. Description of the Related Art Calcium silicate plates are lightweight, nonflammable, and have excellent workability such as cutting and screwing.
Widely used for interior applications such as partition walls and ceilings and exterior applications such as exterior walls and eave ceilings. Further, since the color is close to white, it can be used as it is when it is used for interior decoration, or can be directly painted or finished with a cloth. In general, the calcium silicate plate is subjected to hydrothermal synthesis after drying and forming a slurry obtained by blending an inorganic powder such as a siliceous raw material and a calcareous raw material, a reinforcing fiber, an inorganic filler, and a raw material that has been previously hydrothermally synthesized. The product is cut into lengths. Products,
Since it is desired to be lightweight, it is necessary to make a green sheet as light as possible from the slurry containing the raw materials. For this reason, Japanese Patent Publication No. 55-49023 discloses that a calcium silicate crystalline slurry is blended. In order to make a lightweight molded body, the interlayer strength is weakened,
Further, since the water content is large, in autoclave curing, the vapor pressure of surplus water increases, and the residual air expands, which may cause defects such as blisters and delamination in products.
For this reason, Japanese Patent Application Laid-Open No. 9-20576 discloses that anhydrous gypsum and a curing accelerator are used in combination to produce dihydrate gypsum. What contains anhydrous gypsum on a calcium silicate plate,
It is disclosed in JP-A-6-305807. Although it contains anhydrous gypsum, it is said that the mixing of gypsum dihydrate is essential in the mixing of raw materials from the viewpoint of improving fire resistance.

[0003]

As the construction method is being rationalized, the efficiency of the workability of the calcium silicate plate as the final finishing material is required. Since the product is constructed by hand, it is required that its basic performance be lightweight, and be excellent in workability such as cutting and screwing during construction. For this reason, it is necessary to make a green sheet as light as possible from the raw material slurry, and this is basically achieved by increasing the number of voids that become bubbles, particularly the presence of water. However, during handling in the post-process, delamination may occur during autoclave curing when the pressure is increased or decreased, when the kettle is taken in or out, or when the drying process is performed. It expands, causing delamination between the layers of the plate. For this purpose, it is necessary to reduce voids made of excess water, reduce the amount of air taken in, improve the strength between layers, and prevent defective products.

A green sheet is formed by forming a thin film using a round net machine, a long net machine, or the like, and is wound up by a making roll. The dimensions of the board are 3 × 6,
On the basis of 4 × 8 or 1 × 2 m, larger ones are also manufactured. In order to increase the manufacturing dimensions of the board and to make a thin film, the board becomes uneven in thickness, or the manufacturing felt and the wire mesh surface become uneven, eventually causing unevenness on the product surface or partial Irregularities may occur. In order to use a base material or paint finish as a building material, especially the flatness and smoothness of the board are highly required.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to achieve these objects, and as a result, have found a solution from the aspect of formulation and production, and have completed the present invention. The gist of the present invention is to mix a specific amount of cement, an aluminum compound raw material and an anhydrous gypsum raw material in the slurry in a calcium silicate plate using a raw material slurry containing a siliceous raw material, a calcareous raw material, a reinforcing fiber, and the like. . In addition, cement, aluminum compound raw material, and anhydrous gypsum raw material are mixed with a solid pulverized product (solid powder) obtained by hydrothermally synthesizing siliceous material, calcareous material, fibrous material, etc. in advance,
This is a method for producing a lightweight calcium silicate sheet, in which water is added to this composition to form a slurry, this slurry is formed into a sheet, a green sheet is obtained, the sheet is pressed, and then hydrothermally synthesized. In addition, in the said claim, "the said raw material" shows what removed water from the raw material slurry. An object of the present invention is to achieve weight reduction without increasing the amount of excess moisture and excess voids in a formed green sheet in order to ensure superior lightness. Excess moisture,
When the excess voids increase, the adhesion between the layers deteriorates. The adhesiveness is improved without increasing the moisture and voids.

The object of the present invention is to mix cement, an aluminum compound raw material, and anhydrous gypsum with a part of raw materials to form ettringite in a mixed slurry. The slurry is heated at a temperature of 25 ° C. to 50 ° C. for about 10
Hold for ~ 60 minutes. Ettringite is cement,
3C consisting of aluminum compound, anhydrous gypsum and water
represented by molecular formula of _{aO · Al 2 O 3 · 3CaSO} 4 · 32H 2 0, in the form of a needle crystal. The needle-like crystals are filtered and remain on the surface of the thin film to be formed, like the fibers.
Next, the surfaces are overlapped with each other, and the crystal is entangled between the layers, so that the adhesion is improved. By performing the surface pressing, the adhesion is further improved. In addition, the effect of preventing water cracking during pressing is improved. 32 mol of crystal water of ettringite is taken into the green sheet. The ettringite is generally reacted during the slurry stage to the face pressing stage, but the remaining part is terminated by the steam curing. This product is decomposed by hydrothermal synthesis and contributes to weight reduction. The alumina content becomes part of calcium silicate, the gypsum content becomes anhydrous gypsum, and the water of crystallization evaporates due to the drying in the final step to form voids and reduce the weight.

[0007] Cement is formulated for the purpose of ettringite formation and hydration under atmospheric pressure, with an auxiliary role of interlayer adhesion. Even if only siliceous and calcareous raw materials are blended, there is a risk of delamination without hydration at room temperature or steam curing. The compounding amount of the cement is 5 to 50 parts by weight based on the calcium silicate raw material (hereinafter, each additive raw material is based on the calcium silicate raw material and is indicated by weight). As the type of cement,
General-purpose products such as Portland cement, blast furnace cement, fly ash cement, and alumina cement are used alone or in combination. If the amount of cement increases, the lightness is impaired. If the amount exceeds 50 parts by weight, workability is impaired and whiteness is also problematic.

The aluminum compound raw material is blended for the purpose of forming ettringite. The compounding amount is determined by the contained alumina component. The amount of alumina is 2.0 to 15.0 parts by weight. In the case of an aluminum compound, the alumina content is measured by the amount of alumina produced by the reaction. As the aluminum compound raw material, general-purpose compounds such as aluminum hydroxide, aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum silicate, sodium aluminate, alumino silica gel, and potassium alum are used alone or in combination. Also,
Industrial wastes containing aluminum compounds are also used. The aluminum compound raw material contributes to ettringite formation and improves interlayer adhesion strength. If the alumina content is too high, the compounding amount is 15.0 parts by weight or less because the hydrothermal reaction is inhibited.

[0009] The anhydrous gypsum is blended in an amount of 5 to 60 parts by weight mainly for the production of ettringite. Since the dissolution of the anhydrite is later than that of the aluminum compound, it is added in a slightly excessive amount. When the amount exceeds 60 parts by weight, the effect of weight reduction is lost, the bending strength is reduced, and the interlayer adhesion is adversely affected. The particle size of anhydrous gypsum is 90% for 0.6mm mesh
And the fineness is 2,000 cm ² / g in Blaine value.
It is necessary to be above.

Further, a solid raw material which has been hydrothermally synthesized in advance using a siliceous raw material, a calcareous raw material, an aluminum compound raw material or a raw material containing fibrous material is pulverized, and this is crushed by 10 to 60%.
Parts by weight can be blended. This raw material is useful for achieving weight reduction of the formed green sheet. That is, the newly mixed homogeneous raw material reacts with the unreacted aluminum compound contained in the pulverized product and anhydrous gypsum to produce ettringite, thereby achieving further weight reduction. The particle size of the pulverized product is such that the passage through a 1.2 mm mesh is 95% or more. When the amount exceeds 60 parts by weight, the effect of reducing the weight is reduced, the bending strength is reduced, and the interlayer adhesion is adversely affected.

As the inorganic filler, general-purpose inorganic powders such as slag, limestone, fly ash, wollastonite, mica, kaolin, zeolite, and other clays are added as required. Water can be added to a mixture of these raw materials, a siliceous raw material, a calcareous raw material, and a compound slurry obtained by hydrothermal synthesis in advance to form a slurry.

[0012] This slurry is used for a round net machine, a fourdrinier machine,
Paper is made by a general-purpose paper machine such as a flow-on machine, and a thin film is wound up by a making roll to produce a green sheet. The thickness is adjusted to about 4 to 20 mm. In some cases, the paper is made to a predetermined thickness without using a making roll.

A surface press is performed on the formed green sheet. In the surface press, the upper and lower surfaces of the green sheet are sandwiched between smooth polished iron plates, pressed, and held. The holding pressure is 0.5 to 6.0 N / mm ² . The time to reach the holding pressure is about 5 to 30 minutes. By setting the pressure to 0.5 N / mm ² or more, excessive water gaps and voids unevenly distributed in whole or in part are eliminated, and the rate of delamination failure in a subsequent step is reduced. Further, the problem of unevenness of the production felt and the wire mesh surface can be solved, and the smoothness of the surface can be improved. In particular, the surface of the green sheet mirrors the surface of the polished iron plate and becomes mirror-finished and solid. The whiteness of the plate is improved and the need for surface grinding is eliminated. When the pressure exceeds 6.0 N / mm ² , the weight of the plate becomes too heavy, and the object of weight reduction cannot be achieved. The target specific gravity of the lightweight calcium silicate plate is less than about 1.2.

The pressing speed is an important point in the production because the water content of the green sheet is high. The water content is the amount of water contained in the solid matter. If the time to reach the holding pressure is less than 5 minutes, a defect is generated at the weak point in the uncured sheet. In addition, peeling occurs between the layers or the squeezing speed of water in the plate is too high, so that many crack-like water cracks occur. At the time of dehydration, if a wire mesh is interposed between the iron plates, water breakage can be prevented, but the surface property is impaired.

[0015] The green sheet is subjected to steam curing at a temperature of 30 to 80 ° C for 1 to 10 hours after the plate making, and the reaction of the cement and the remaining hydrated ettringite proceeds slowly. The remaining ettringite grows in excess water and voids, and contributes to improving interlayer adhesion. Thereafter, hydrothermal synthesis is performed by an autoclave. The autoclave temperature is about 160 to 190 ° C., and is performed for 5 to 20 hours or more. By autoclaving, calcium silicate hydrate is formed from the siliceous raw material including cement, the calcareous raw material, and the hydrothermally synthesized unreacted portion of the pulverized material. Ettringite produced from cement, an aluminum compound, anhydrous gypsum and the like is decomposed in this curing, and water of crystallization remains in the plate as water pores, and is evaporated by drying later to form pores, which contributes to weight reduction. The surface becomes smooth and dense by surface pressing, and the inside is reduced in weight due to the presence of voids and calcium silicate crystals, hydrothermal compounds or calcium silicate crushed materials (solid powder) generated by such a drying process. Improves adhesion and processability.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a siliceous raw material, 15 to 50 parts by weight of a general-purpose powder such as diatomaceous earth, silica stone, silica fume and the like is used. As the calcareous raw material, 15 to 50 parts by weight of a general-purpose powder such as lime and slaked lime is used. The pre-synthesized hydrothermal slurry can be obtained from various siliceous and lime raw materials such as diatomaceous earth, silica stone and silica fume as described above and excess water as raw materials. The type of raw materials and the pressure for synthesis
The slurry becomes an amorphous slurry or a crystalline slurry depending on the atmospheric pressure or the high-pressure steam atmosphere. As the reinforcing fiber, pulp is mainly used, and polypropylene, rayon, various kinds of hemp, and 2 to 15 parts by weight of general-purpose organic and inorganic fibers such as glass fiber and alkali-resistant glass fiber are used.
Further, 0 to 40 parts by weight of an inorganic filler is blended as required. These raw material slurries contain crystalline or amorphous hydrothermal compound slurries synthesized in advance.

Cement / aluminum compound raw materials and anhydrous gypsum raw materials are mixed in predetermined amounts. Further, a pulverized product of a hydrothermally synthesized solid material composed of a siliceous raw material and / or an aluminum compound raw material is also blended. Cement is silicic acid
It can be used as one type of calcareous raw material. Including them, the ratio of siliceous to calcareous is 0.5 to 2.0
It is about. These raw material blends are kneaded with water to form a slurry, and the slurry is formed by a generally used paper machine such as a round-mesh machine, a long-mesh machine, or a flow-on machine. The obtained sheet is pressed under a predetermined pressure to obtain a green sheet. This green sheet is subjected to predetermined steam curing and autoclave curing.

[0018]

EXAMPLES Examples 1 to 15 were produced based on the raw material composition and production conditions shown in Table 1. The raw material composition was expressed as a whole in% by weight. Paper is formed by a normal round-mesh paper-making machine, wound up in four layers on a making roll, 6 mm in thickness and 9 in size.
A green sheet of 10 × 1820 mm is obtained. The sheet was subjected to surface pressing at a predetermined pressure increasing speed and holding pressure, subjected to steam curing at 60 ° C. for 3 hours, and then subjected to 175
The autoclave curing was performed at 150C for 15 hours. The plate was dried and tested, and the results are shown in Table 2. Similarly, Comparative Examples 1 to 8 were produced based on the raw material composition and production conditions shown in Table 3, and the results are shown in Table 4.

[0019]

The object of the present invention is to produce ettringite crystals in a slurry of a raw material mixture when producing a calcium silicate plate. This ettringite is a needle-like crystal, and is filtered off on the surface of a thin film to be formed like a fiber. These crystals are entangled between the layers where the planes are overlapped with each other, so that the adhesion is improved. Ettringite generally has 32 moles of water of crystallization, but is decomposed by autoclaving and then evaporated by drying to form voids, which contributes to weight reduction. Cement hydrates under ettringite formation and atmospheric pressure to provide the auxiliary effect of interlayer adhesion. By performing the surface pressing, the rate of delamination failure can be further reduced. In addition, the occurrence of irregularities on the production felt and the wire mesh surface could be eliminated, and the surface smoothness was improved. In particular, the surface of the polished iron plate is copied, and the surface of the green sheet becomes mirror-like and dense. The whiteness of the product has been improved and the need for surface grinding has been eliminated. Moreover, the peeling failure rate in the manufacturing was significantly reduced, and the productivity was improved. Furthermore, as a building material, it is nonflammable, has excellent workability such as cutting and screwing, and can be directly painted or cloth finished as it is.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4] Powdered silica: Chichibu Mining Co., Ltd., Blaine value 3600cm ² /
g Limestone: Okutama Kogyo Co., Ltd. Anhydrite: hydrofluoric anhydride gypsum, Blaine value 2800 cm ²
/ G Al ₂ O ₃ : aluminum sulfate 17%, aluminum hydroxide (aluminum sludge) 48% Hydrothermal compound slurry: calcareous / siliceous ratio 0.90,
Solid / water ratio: 0.10 Solid powder A: 100% pulverized product of Example 2, particle size 1.2 mm passing 100% Solid powder B: pulverized product of Comparative Example 4, 100% particle size passing 1.2 mm : N / mm ² Pressurizing time: Time from start to holding of pressurization of the press (the time for holding the pressure per minute is 4
Min) Moisture content after pressing: Measurement result of green sheet after pressing (%) Specific gravity: measured according to JIS A5430 Flexural strength: measured according to JIS A5430 (N / mm ² ) Length change rate: measured according to JIS A5430 ( %) Interlayer strength: Bidirectional tensile strength (N
/ Mm ² ) Surface properties: good surface smoothness without irregularities on the surface, good, slightly bad, bad x Water splitting property: no cracks (water cracks) near both sides, good, slightly good, yes x Peelability: 3 Cut 10 × 6-inch plates from the center and observe the adhesion of the plates, such as delamination between layers (confirmed with the cured product after drying) No peeling ○, 2 to 3 peels or less, slight condition △, 5 or more peeling or slight peeling x

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) C04B 22:06 7:02) 111: 40 (72) Inventor Hirofumi Ueda 2-12 Shiba-Daimon, Minato-ku, Tokyo No. 10 F-term in Asano Slate Co., Ltd. (reference) 4G012 MA00 MB23 PA04 PA15 PA22 PA24 PB04 PB11 PC15 4G052 GA02 GB06 GB22 GB34 GB84

Claims (8)

[Claims] 1. A method for producing a calcium silicate plate obtained by forming a raw material slurry containing a siliceous raw material, a calcareous raw material and a reinforcing fiber and hydrothermally synthesizing the formed plate, wherein 100 parts by weight of the raw material is cement, A method for producing a lightweight calcium silicate plate, comprising mixing 10 to 100 parts by weight of an additive material consisting of an aluminum compound raw material and an anhydrous gypsum raw material, forming a slurry to obtain a green sheet, and hydrothermally synthesizing the green sheet. . 2. A method for producing a calcium silicate plate obtained by forming a raw material slurry containing a siliceous raw material, a calcareous raw material, a reinforcing fiber, and an inorganic filler, and hydrothermally synthesizing the formed paper plate. In the parts, 20 to 17 were added raw materials consisting of cement, aluminum compound raw materials, anhydrous gypsum raw materials, and hydrothermally synthesized calcium silicate solids.
A method for producing a lightweight calcium silicate sheet, which comprises mixing 0 parts by weight, sheeting this slurry to obtain a green sheet, pressing the green sheet and then hydrothermally synthesizing. 3. The method according to claim 1, wherein the amount of the cement is 5 to 50.
The method for producing a lightweight calcium silicate plate according to claim 1 or 2, wherein the amount is part by weight. 4. The method for producing a lightweight calcium silicate plate according to claim 1, wherein the amount of alumina from the aluminum compound raw material is 2 to 15 parts by weight based on the raw material. 5. An anhydrous gypsum raw material based on the raw material is 5 to 5.
The method for producing a lightweight calcium silicate plate according to claim 1 or 2, wherein the amount is 60 parts by weight. 6. A pulverized product of a hydrothermally synthesized calcium silicate solid is composed of a siliceous raw material, a calcareous raw material, and a reinforcing fiber, and the compounding amount thereof is 10 to 60 parts by weight based on the raw material. The method for producing a lightweight calcium silicate plate according to claim 2, characterized in that: 7. A pulverized product of a hydrothermally synthesized calcium silicate solid is a siliceous raw material, a calcareous pigment, a reinforcing fiber, anhydrite,
3. The lightweight calcium silicate plate according to claim 2, wherein the content is 1.0 to 7.0% by weight as an alumina component, and the compounding amount is 10 to 60 parts by weight based on the raw material. Manufacturing method. 8. The green sheet has a thickness of 0.5 to 6.0 N / m.
method of manufacturing a lightweight calcium silicate board according to claim 2, wherein the performing in terms pressing pressure m ^2.