Sheet formed in layers and method for manufacturing the same

Abstract

LAYERED SHEET AND METHOD FOR MANUFACTURING THE SAME. The present invention relates to a layered sheet comprising two or more formed sheets, each formed from a curable composition comprising (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) alkali-resistant fibers other than cellulose-based fibers, wherein the aluminosilicate source (A) comprises blast furnace slag, and the blast furnace slag content with a specific surface area of ​​1000 cm2 / g or more and 9000 cm2 / g or less is greater than 55% by mass and less than 90% by mass, relative to the total solids content in the curable composition.

Description

Descriptive Report of the Invention Patent for LAYERED SHEET AND METHOD FOR MANUFACTURING THE SAME. TECHNICAL FIELD

[0001] The present invention relates to a layered sheet and a method for manufacturing the same. BACKGROUND OF THE TECHNIQUE

[0002] Until now, cementitious board made by a paper-making method has been produced by forming a sheet through a paper-making method, in which a paste prepared by suspending cement and fibers in an aqueous medium is excavated with a screen and then the sheet is cured. The paper-making method has been used in a wide variety of fields due to its versatility of general use, and has been used particularly as ceiling lining material, interior material, exterior material, flooring material and the like in the field of architecture. However, enormous energy is required for cement production, and the discharge of a large amount of carbon dioxide associated with the enormous energy has been seen as a problem. In recent years, studies have been made on an inorganic polymer produced by the reaction of an aluminosilicate with an alkali metal silicate.Inorganic polymers have been the focus because they are superior in terms of durability and acid resistance compared to cementitious materials, and the amount of carbon dioxide released during the period from raw material production to inorganic polymer production is significantly small. Therefore, inorganic polymers are believed to be an environmentally friendly material.

[0003] For example, Patent Document 1 describes an inorganic sheet characterized by being a cured composite of a matrix. Petition 870240053156, dated 06 / 24 / 2024, page 5 / 57 2 / 44 produced by dehydrating a paste containing blast furnace slag in an amount of 30 to 53% by mass, gypsum with an average particle diameter of 200 to 2000 μm in an amount of 2 to 5% by mass, an alkaline material in an amount of 5 to 11% by mass, reinforcing fibers in an amount of 5 to 15% by mass, and an inorganic mixture in an amount of 31 to 50% by mass relative to the total solids content, and having a ratio (blast furnace slag):(gypsum):(alkaline material) of 1:(0.05 to 0.15):(0.15 to 0.35) by mass, thus forming the dehydrated product.

[0004] Patent Document 2 describes an asbestos-free hydraulic sheet made by a papermaking method, which is characterized by containing polyvinyl alcohol-based fibers with a cross-sectional circularity of 40 to 70% in an amount of 1.0 to 2.0% by mass relative to the total solids content, and eucalyptus pulp with a freedom of 100 to 500 ml in an amount of 2.0 to 4.0% by mass relative to the total solids content, and also characterized by having an adhesion strength between layers of 2.0 N / mm2 or more, and a dimensional change rate of 0.25% or less. DOCUMENT OF THE PRECEDENT TECHNIQUE PATENT DOCUMENTS

[0005] Patent Document 1: JP-A-2013-216534

[0006] Patent Document 2: JP-A-2006-076874

[0007] Patent Document 3: WO 2019 / 131321 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, a non-cementitious board made by a paper-making method with superior properties is still needed. In Patent Document 1, blast furnace slag is mixed in as an environmentally friendly raw material. However, the Petition 870240053156, dated 06 / 24 / 2024, page 6 / 57 3 / 44 The amount of blast furnace slag mixture is very small. Therefore, the bending strength of the plate is weak, and further improvement in the dimensional stability of the plate is still needed.

[0009] Patent Document 3 describes a compound formed from a curable composition containing (A) at least one aluminosilicate source, (B) an alkali metal hydroxide, (C) a calcium ion supply source, and (D) alkali-resistant fibers, wherein the aluminosilicate source (A) contains a specific aluminosilicate source. This formed compound is produced by a forming method, such as a casting method, a dehydration molding method, an injection molding method, and an extrusion method. In this document, a plate made by a papermaking method is excluded from the scope of the invention.

[0010] In these situations, the present invention addresses the problem of providing a layered sheet that is reinforced with fibers and has high flexural strength, high impact resistance, and high dimensional stability. SOLUTIONS TO THE PROBLEMS

[0011] In order to solve the problem, the present inventors have conducted extensive and intensive studies on layered sheets. As a result, the present invention has been realized. The present invention includes the following preferred aspects. [1] A layered sheet comprising two or more formed sheets, each formed from a curable composition comprising (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) alkali-resistant fibers other than cellulose-based fibers, wherein the aluminosilicate source (A) comprises blast furnace slag, and the blast furnace slag content having a specific surface area of ​​1000 cm2 / g or more and 9000 cm2 / g or less is greater than 55% by mass and Petition 870240053156, dated 06 / 24 / 2024, page 7 / 57 4 / 44 less than 90% by mass, in relation to the total solids content in the curable composition. [2] The sheet formed in layers according to [1], wherein the alkali metal hydroxide content (B) is 3 % by mass or more and 45 % by mass or less, in relation to a total solids content in the curable composition. [3] Layered sheet formed according to [1] or [2], wherein the cellulose (C) fiber content is 0.5 % by mass or more and 15 % by mass or less, relative to a total solids content in the layered sheet. [4] A sheet formed in layers according to any one of [1] to [3], wherein the content of alkali-resistant fibers other than cellulose-based fibers (D) is 0.1 % by mass or more and 5 % by mass or less, relative to a total solids content in the sheet formed in layers. [5] The sheet formed in layers according to any one of [1] to [4], wherein the aluminosilicate source (A) further contains at least one selected from the group consisting of fly ash, metakaolin and red mud in a content of 1 % by mass or more and 35 % by mass or less, in relation to a total solids content in the curable composition. [6] The sheet formed in layers according to any one of [1] to [5], wherein the alkali metal hydroxide (B) is slaked lime. [7] The sheet formed in layers according to any one of [1] to [6], in which the cellulose-based fibers (C) are pulps. [8] The sheet formed in layers according to any one of [1] to [7], wherein the alkali-resistant fibers other than cellulose-based fibers (D) have an average fiber diameter of 100 μm or less, and an elongation ratio of 50 or more and 2000 or less. [9] The sheet formed in layers according to any of [1] to Petition 870240053156, dated 06 / 24 / 2024, page 8 / 57 5 / 44 [8], wherein alkali-resistant fibers other than cellulose-based fibers (D) are at least one type of fiber selected from the group consisting of polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers and nylon fibers.

[10] Sheet formed in layers according to any one of [1] to [9], wherein the impact strength of the sheet formed in layers is 2 kJ / m2 or more, as measured in accordance with JIS K 7111.

[11] A method for manufacturing a sheet formed in layers according to any one of [1] to

[10] , the method comprising: a step to mix an aluminosilicate source (A), an alkali metal hydroxide (B), cellulose-based fibers (C), alkali-resistant fibers other than cellulose-based fibers (D), and water, together to prepare a curable composition; A step in producing a sheet formed by a papermaking method using curable composition; and a lamination step of two or more sheets formed one on top of the other.

[12] The method according to

[11] , in which the step to produce the sheet formed by the papermaking method comprises excavating the curable composition with a cylindrical wire. EFFECTS OF THE INVENTION

[0012] According to the present invention, a layered sheet can be provided that is reinforced with fibers and has high flexural strength, high impact resistance and high dimensional stability. MODALITIES OF THE INVENTION

[0013] The layered sheet formed according to the present invention comprises two or more formed sheets, each formed from a curable composition comprising (A) a source of Petition 870240053156, dated 06 / 24 / 2024, page 9 / 57 6 / 44 aluminosilicate, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) alkali-resistant fibers other than cellulose-based fibers. The aluminosilicate source (A) contains a blast furnace slag, wherein the blast furnace slag content with a specific surface area of ​​1000 cm2 / g 9000 cm2 / g is greater than 55% by mass and less than 90% by mass, relative to a total solids content in the curable composition. (A) Aluminosilicate source

[0014] The aluminosilicate source contains an aluminosilicate (xM2O«yAl2O3'zSiO2«nH2O, where M represents an alkali metal) as the major component. The term “major component”, as used in this document, refers to a component contained in a major mass in the aluminosilicate source. The aluminosilicate source elutes cations, such as aluminum ions and silicon ions, upon contact with a highly alkaline solution [an aqueous solution of an alkali metal hydroxide (B)], and the aluminosilicate source is polycondensed to form a strong SiO4*AlO4 polymer network.

[0015] The aluminosilicate source (A) to be used in the present invention contains blast furnace slag. Therefore, according to the present invention, blast furnace slag, which is a waste material produced in an iron manufacturing process, can be effectively used.

[0016] The present inventors have found that the following matters may be considered. That is, when the specific surface area of ​​a blast furnace slag is very small, there are few reaction sites in the blast furnace slag, resulting in insufficient progression of a curing reaction. On the other hand, when the specific surface area of ​​a blast furnace slag is very large, the average particle diameter of the blast furnace slag becomes smaller, and the blast furnace slag cannot be retained by a papermaking screen. Petition 870240053156, dated 06 / 24 / 2024, page 10 / 57 7 / 44 when, for example, the layered sheet is produced by a papermaking method, resulting in a reduction of the ratio of blast furnace slag to excavated solid content with the screen. Furthermore, the present inventors have conducted detailed studies on blast furnace slags and, as a result, have found that, in a layered sheet comprising two or more formed sheets, each formed from a curable composition comprising components (A) to (D), the layered sheet can have high flexural strength, high impact strength, and high dimensional stability, when the blast furnace slag content with a specific surface area of ​​1000 cm2 / g 9000 cm2 / g is greater than 55% by mass and less than 90% by mass, relative to a total solids content in the curable composition.If the content is 55% by mass or less, it is difficult to impart the desired flexural strength, impact strength, and dimensional stability to the layered sheet. If the content is 90% by mass or more, it is difficult to impart the desired flexural strength, impact strength, and dimensional stability to the layered sheet. This is assumed to be due to the very high content of blast furnace slag, whereby it is not possible to obtain an ideal mixing ratio between the alkali metal hydroxide (B), the cellulose-based fibers (C), and the alkali-resistant fibers (D). However, all the mechanisms mentioned above are assumptions, and the present invention is not limited to them.

[0017] Furthermore, even when the curable composition contains blast furnace slag with a specific surface area of ​​less than 1000 cm² / g in an amount greater than 55% by mass relative to the total solids content in the curable composition, it is difficult to produce a layered sheet with the desired flexural strength, impact strength, and dimensional change rate. Even when the curable composition contains blast furnace slag with an area of Petition 870240053156, dated 06 / 24 / 2024, page 11 / 57 8 / 44 specific surface area greater than 9000 cm2 / g in an amount of 60% by mass or more relative to the total solids content in the curable composition, it is also difficult to produce a layered sheet with the desired flexural strength, impact strength and dimensional change rate.

[0018] The blast furnace slag content with the specific surface area described is preferably 60% by mass or more, more preferably 62% by mass or more, even more preferably 65% ​​by mass or more, particularly preferably 68% by mass or more, and is preferably 85% by mass or less, more preferably 82% by mass or less, even more preferably 80% by mass or less, particularly preferably 75% by mass or less.When the content is equal to or greater than the lower limit mentioned above and equal to or less than the upper limit mentioned above, for example, in the production of layered sheet by a papermaking method, the blast furnace slag having sufficient reaction sites is contained in a sufficient ratio to a solids content excavated with the screen, an ideal mixing ratio between the alkali metal hydroxide (B), the cellulose-based fibers (C) and the alkali-resistant fibers (D) can be achieved. As a result, higher flexural strength, higher impact resistance and greater dimensional stability can be obtained in the layered sheet produced.

[0019] The specific surface area of ​​blast furnace slag contained in a content greater than 55% by mass and less than 90% by mass, relative to the total solids content in the curable composition, is preferably 2000 cm² / g or more, more preferably 3000 cm² / g or more, preferably 8000 cm² / g or less, most preferably 7000 cm² / g or less. When the specific surface area of ​​the blast furnace slag is equal to or greater than the aforementioned lower limit Petition 870240053156, dated 06 / 24 / 2024, p. 12 / 57 9 / 44 above and equal to or below the upper limit mentioned above, blast furnace slag may have sufficient reaction sites and may have a suitable average particle diameter. As a result, higher flexural strength, higher impact resistance, and greater dimensional stability can be obtained in the formed sheet produced in layers. The specific surface area of ​​blast furnace slag can be adjusted to a value equal to or greater than the lower limit mentioned above, and equal to or less than the upper limit mentioned above, for example, by pulverizing the blast furnace slag, then classifying the pulverized product, and using a specific fraction from among the classified fractions. The specific surface area of ​​blast furnace slag can be measured, for example, by a laser diffraction / scattering method.

[0020] Blast furnace slags are commercially available, and each product with a specific surface area of ​​1,000 cm2 / g or more or 9,000 cm2 / g or less can be used individually, or two or more of them can be used in combination.

[0021] Blast furnace slag types include air-cooled slag which has a crystalline form, and granulated slag which has an amorphous form, and either of these slags can be used in the present invention. From the point of view of further improving the strength of the layered sheet and further promoting the curing of the layered sheet, granulated slag is preferably used.

[0022] Preferred examples of the aluminosilicate source (A), in addition to blast furnace slag with the specific surface area described, include: an industrial waste material, such as fly ash, red mud and burnt sewage sludge ash; naturally occurring aluminosilicate minerals and their calcined products (e.g., metakaolin); and volcanic ash. These substances are commercially available. In the present invention, these substances can be Petition 870240053156, dated 06 / 24 / 2024, page 13 / 57 10 / 44 used individually, or two or more of them may be used in combination. Provided that the effects of the present invention cannot be deteriorated, the curable composition of the present invention may contain a blast furnace slag with a specific surface area of ​​less than 1000 cm2 / g, and / or a blast furnace slag with a specific surface area greater than 9000 cm2 / g.

[0023] In one aspect of the present invention, the aluminosilicate source (A) also contains at least one selected from the group consisting of fly ash, metakaolin and red mud in a content of preferably 1% by mass or more, preferably 35% by mass or less, relative to a total solids content in the curable composition, in addition to blast furnace slag with the specific surface area described. In this aspect, the density of a cured compound can be increased compared to that obtained when blast furnace slag is used alone as the aluminosilicate source (A). As a result, a layered sheet with higher flexural strength, higher impact resistance and higher dimensional stability can be produced.In this aspect, the content is more preferably 3% by mass or more, even more preferably 4% by mass or more, in addition to more preferably 5% by mass or more, particularly preferably 6% by mass or more, and is more preferably 34% by mass or less, even more preferably 33% by mass or less, in addition to more preferably 32% by mass or less, particularly preferably 30% by mass or less (for example, 28% by mass or less, 26% by mass or less, 24% by mass or less, 22% by mass or less, 20% by mass or less, 18% by mass or less). In a preferred aspect, the content is preferably 15% by mass or less, more preferably 13% by mass or less, even more. Petition 870240053156, dated 06 / 24 / 2024, page 14 / 57 11 / 44 preferably 12% by mass or less, particularly preferably 10% by mass or less. When fly ash is contained as the source of aluminosilicate (A), the fly ash content is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and is preferably 25% by mass or less, more preferably 23% by mass or less, even more preferably 21% by mass or less, in addition to more preferably 15% by mass or less, particularly preferably 13% by mass or less, particularly more preferably 12% by mass or less, in relation to a total solids content in the curable composition. The fly ash content may be 5% by mass or more, 6% by mass or more, or 8% by mass or more, or it may be 7% by mass or less, or 6% by mass or less.When red mud is contained as the source of aluminosilicate (A), the red mud content is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, in addition to more preferably 5% by mass or more, even more preferably 7% by mass or more, particularly preferably 9% by mass or more, especially preferably 11% by mass or more, and is preferably 35% by mass or less, more preferably 33% by mass or less, even more preferably 30% by mass or less, in addition to more preferably 28% by mass or less, particularly preferably 25% by mass or less, particularly more preferably 20% by mass or less, in relation to a total solids content in the curable composition.The red mud content may be 15% by mass or more, or 20% by mass or more, or it may be 15% by mass or less, or 10% by mass or less, or 8% by mass or less, or 6% by mass. Petition 870240053156, dated 06 / 24 / 2024, page 15 / 57 12 / 44 or less. The blast furnace slag content with the specific surface area described is preferably 56% by mass or more, more preferably 57% by mass or more, even more preferably 58% by mass or more, in addition to more preferably 60% by mass or more, particularly preferably 62% by mass or more (in one aspect, for example, 64% by mass or more, preferably 67% by mass or more, more preferably 70% by mass or more), and is preferably 87% by mass or less, more preferably 84% by mass or less, even more preferably 82% by mass or less, in addition to more preferably 78% by mass or less (in one aspect, 77% by mass or less, for example), in relation to a total solids content in the curable composition.When the content is equal to or greater than the lower limit mentioned above and equal to or less than the upper limit mentioned above, the effects caused by the addition of at least one selected from the group consisting of fly ash, metakaolin and red mud can be achieved. (B) Alkali metal hydroxide

[0024] The alkali metal hydroxide (B) to be used in the present invention exhibits high alkalescence in water, and has activity to activate the aluminosilicate source (A) and elute cations, such as Al ions and Si ions, upon contact with the aluminosilicate source (A).

[0025] Examples of alkali metal hydroxide (B) include slaked lime, unslaked lime, and sodium hydroxide. From the point of view that problems of metal hydroxide runoff into process circulating water or dilution of metal hydroxide by process circulating water in the papermaking method can be avoided, it is preferable to use slaked lime as the alkali metal hydroxide (B).

[0026] The alkali metal hydroxide (B) content is preferably Petition 870240053156, dated 06 / 24 / 2024, page 16 / 57 13 / 44% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, in addition to more preferably 7% by mass or more, particularly preferably 8% by mass or more, and is more preferably 45% by mass or less, even more preferably 43% by mass or less, particularly preferably 41% by mass or less, in relation to a total solids content in the curable composition. In a preferred aspect, the content is preferably 10% by mass or more, and is preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 22% by mass or less, particularly preferably 20% by mass or less, in relation to a total solids content in the curable composition.When the content is equal to or greater than the lower limit mentioned above and equal to or less than the upper limit mentioned above, greater flexural strength, greater impact resistance, and greater dimensional stability can be achieved in a formed sheet produced in layers. (C) Cellulose-based fibers.

[0027] The cellulose (C) based fibers to be used in the present invention have the effect of improving the bending strength and impact strength of the sheet formed in layers.

[0028] Examples of cellulose (C)-based fibers include rayon fibers (including polynosic rayon fibers and organic solvent-based cellulose fibers), acetate-based fibers, and natural cellulose-based fibers such as natural pulp (e.g., wood pulp, cotton linter pulp, hemp, slurry). Among these fibers, from the point of view that the yield of the cylinder screen process during sheet making in the papermaking method can be improved, it is preferable to use natural pulp, more preferably slurry. Therefore, in a preferred aspect of the present invention, the cellulose (C)-based fibers are pulps. Petition 870240053156, dated 06 / 24 / 2024, page 17 / 57 14 / 44

[0029] The pulp may or may not undergo a beating treatment. From the point of view that the desired flexural strength and impact resistance can be achieved, it is preferable to use beaten pulp, and it is more preferable to use pulp with a CSF value, which indicates a degree of beating according to the Canadian standard in a freedom test method prescribed in JIS P8121-1976, of 50 to 400 mL, more preferably 100 to 150 mL.

[0030] Like pulp, a wide variety of pulp types can be used. Examples of pulp include needle-leaf tree, broadleaf tree, Manila hemp, paper bush (Edgeworthia chrysantha), paper mulberry (Broussonetia kazinoki), gampi (Diplomorpha sikokiana), sarago (Wikstroemia spp.), mulberry, straw, bamboo, reed, saby, lalang, esparto grass, bagasse, sisal, kenaf, linter, banana, and recycled water paper. Examples of needle-leaf trees include needle-leaf trees belonging to the families Taxodiaceae, Pinaceae, Cupressaceae, and Araucariaceae. Examples of broadleaf trees include broadleaf trees belonging to the families Ulmaceae, Fagaceae, Myrtaceae, Cercidiphyllaceae, Oleaceae, Rutaceae, Betulaceae, Aceraceae, Juglandaceae, Tiliaceae, Araliaceae, Sapotaceae, Celastraceae, Apocynaceae, Verbenaceae, Magnoliaceae, and Seculiaceae. These pulps can be bleached or unbleached pulps.These pulps can be used individually, or two or more of them can be used in combination.

[0031] The fiber content based on cellulose (C) is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, particularly preferably 3% by mass or more, and is more preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 9% by mass or less, particularly preferably 5% by mass or less, in relation to Petition 870240053156, dated 06 / 24 / 2024, page 18 / 57 15 / 44 a total solids content in the layered sheet. When the content is equal to or greater than the lower limit mentioned above, blast furnace slag can be sufficiently retained by the papermaking screen when, for example, a layered sheet is produced by the papermaking method and, consequently, a satisfactory yield can be obtained. Furthermore, blast furnace slag can be contained in a sufficient content in a solid material excavated with the screen and, therefore, the desired flexural strength and impact resistance can be achieved. When the content is equal to or less than the upper limit mentioned above, problems such as deterioration in the water resistance of the layered sheet and deterioration in the effect of preventing the invasion of a corrosive substance (chlorine, carbon dioxide gas, and sulfate ions, and various organic acids such as sulfate ions) can be avoided. (D) Alkali-resistant fibers other than cellulose-based fibers

[0032] The alkali-resistant fibers other than cellulose-based fibers (D) used in the present invention have the effect of improving the bending strength and impact strength of the layered sheet. It has been found that the reinforcing effect of the fibers can be improved when cellulose-based fibers (C) and alkali-resistant fibers other than cellulose-based fibers (D) (wherein alkali-resistant fibers other than cellulose-based fibers (D) are also referred to as “alkali-resistant fibers (D)” hereafter) are used in combination.

[0033] Alkali-resistant fibers (D) can be either inorganic or organic fibers, provided the fibers have chemical durability against alkalis. Examples of alkali-resistant inorganic fibers include alkali-resistant glass fibers and carbon fibers. Examples of alkali-resistant organic fibers include Petition 870240053156, dated 06 / 24 / 2024, page 19 / 57 16 / 44 various alkali-resistant fibers, such as polyvinyl alcohol-based fibers (also abbreviated as “PVA”, hereinafter), polyolefin-based fibers (e.g., polyethylene fibers and polypropylene fibers), ultra-high molecular weight polyethylene fibers, polyamide-based fibers (e.g., polyamide 6, polyamide 6.6, and polyamide 6.10), aramid fibers (particularly para-aramid fibers), poly-p-phenylenebenzobisoxazole-based fibers [e.g., poly-p-phenylenebenzoxazole (PBO) fibers], nylon fibers, acrylic fibers, polyphenylene sulfide fibers (PPS fibers), and polyether ether ketone fibers (PEEK fibers). These types of alkali-resistant fibers can be used individually, or two or more of them can be used in combination.

[0034] Among these fibers, polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers, and nylon fibers are preferably used, from the point of view that superior reinforcing properties can be imparted to the layered sheet, and the layered sheet can be produced at a lower cost. Therefore, in one aspect of the present invention, alkali-resistant fibers other than cellulose-based fibers (D) can be at least one type of fiber selected from the group consisting of polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers, and nylon fibers.

[0035] The average fiber diameter of alkali-resistant fibers (D) is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 50 μm or less, and is preferably 3 μm or more, more preferably 5 μm or more, even more preferably 7 μm or more. When the average fiber diameter of alkali-resistant fibers (D) is equal to or less than the upper limit mentioned above, the alkali-resistant fibers may also have sufficient fiber strength and may be produced in a market. Petition 870240053156, dated 06 / 24 / 2024, page 20 / 57 17 / 44 industrial in a stable manner. When the average fiber diameter of the alkali-resistant fibers (D) is equal to or greater than the lower limit mentioned above, the fiber can be dispersed more uniformly in a polymer matrix. The term “polymer matrix,” as used herein (also referred to simply as “matrix” hereafter), refers to a portion of the polymer that binds to the alkali-resistant fibers in the layered sheet.

[0036] Each of the alkali-resistant fibers (D) has an elongation ratio preferably of 50 or more, more preferably of 150 or more, even more preferably of 200 or more, and preferably of 2000 or less, more preferably of 1200 or less, even more preferably of 800 or less, from the point of view that both satisfactory dispersibility of the fibers in the curable composition and satisfactory reinforcing properties after curing of the curable composition can be achieved. The term “elongation ratio”, as used in this document, refers to a ratio (L / D) of an average fiber length L and an average fiber diameter D.

[0037] The average fiber diameter and elongation ratio of alkali-resistant fibers (D) can be determined according to the “fiber classification chemical test method (8.5.1)” prescribed in JIS L 1015.

[0038] From the point of view that both satisfactory dispersibility of the fibers in the curable composition and satisfactory reinforcement properties after curing of the curable composition can be achieved, the average fiber length of the alkali-resistant fibers (D) is preferably from 0.5 mm to 20 mm, more preferably from 1 mm to 15 mm.

[0039] The tensile strength of alkali-resistant fibers (D) in Petition 870240053156, dated 06 / 24 / 2024, page 21 / 57 18 / 44 of the present invention is preferably 3 cN / dtex or more, more preferably 5 cN / dtex or more, particularly preferably 7 cN / dtex or more. When the tensile strength of the alkali-resistant fibers is equal to or greater than the lower limit mentioned above, the reinforcement performance for the layered sheet can be improved. The upper limit of the tensile strength of the alkali-resistant fibers (D) in the present invention can be appropriately defined depending on the fiber types and is, for example, 30 cN / dtex or less. The tensile strength of the fiber can be determined according to the “fiber classification chemical test method (8.5.1)” prescribed in JIS L 1015.

[0040] When PVA-based fibers, for example, vinylone fibers, are used as alkali-resistant fibers (D), PVA-based fibers with the following properties may be used. The degree of polymerization of a PVA-based polymer constituting the PVA-based fibers may be appropriately selected depending on the intended use, and is not particularly limited. Taking into account the mechanical and similar properties of the fibers produced, the average degree of polymerization of the PVA-based polymer determined from the viscosity of an aqueous solution at 30°C is preferably from about 500 to 20,000, more preferably from about 800 to 15,000, particularly preferably from about 1,000 to 10,000. From the point of view of the strength of the fibers produced, the average degree of polymerization of the PVA-based polymer is preferably 1000 or more, more preferably 1200 or more, most preferably 1500 or more, and particularly preferably 1750 or more.PVA-based polymers can be medium-grade polymerization products, with a medium degree of polymerization of 1,000 or more and less than 3,000, or they can be high-grade polymerization products, with a medium degree of polymerization of 3,000 or more. Petition 870240053156, dated 06 / 24 / 2024, page 22 / 57 19 / 44

[0041] The degree of saponification of the PVA-based polymer can also be appropriately selected depending on the intended use and is not particularly limited. From the point of view of the dynamic properties of the fibers produced, the degree of saponification of the PVA-based polymer can be, for example, 95 mol% or more, preferably 98 mol% or more. The degree of saponification of the PVA-based polymer can be 99 mol% or more, and can be 99.8 mol% or more. When the degree of saponification of the PVA-based polymer is equal to or greater than the lower limit mentioned above, satisfactory mechanical properties, satisfactory process passage properties, satisfactory production cost and the like of the fibers produced can be achieved.

[0042] The PVA-based fibers to be used in the present invention can be produced by dissolving the PVA-based polymer in a solvent, spinning the resulting solution by any one of a wet process, a dry-wet process, or a dry process, and subjecting the spun product to dry heat stretching. Wet spinning is a method for ejecting a spinning stock solution into a curing bath through a spinning nozzle directly. Dry-wet spinning is a method for ejecting a spinning stock solution into air or an inert gas located separately by an arbitrary temporal distance through a spinning nozzle and subsequently introducing the spinning stock solution into a curing bath. Dry spinning is a method for ejecting a spinning stock solution into air or an inert gas. After spinning, the PVA-based fibers can be subjected to a stretching treatment, if necessary.Furthermore, PVA-based fibers can undergo acetalization or similar treatment, which has been commonly used on PVA-based fibers.

[0043] The solvent to be used in the stock solution for spinning PVA-based fibers is not particularly limited, provided that the PVA Petition 870240053156, dated 06 / 24 / 2024, page 23 / 57 20 / 44 can be dissolved in the solvent. Examples of solvents include water, dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, and a polyhydric alcohol (e.g., glycerin, ethylene glycol, triethylene glycol). These solvents can be used individually, or two or more of them can be used in combination. In the present invention, when wet spinning is performed, it is preferable to use water or an organic solvent as the solvent. Among these solvents, from the point of view of solvent feed ease and the solvent's influence on environmental impact, water and DMSO are particularly preferred. The polymer concentration in the spinning stock solution can vary depending on the composition and degree of polymerization of the PVA-based polymer and the type of solvent, generally being from 6 to 60% by mass.

[0044] In dry spinning, the solvent mentioned above can be used. In this case, water can be used or an organic solvent can be used.

[0045] Provided that the effects of the present invention cannot be deteriorated, in addition to the PVA-based polymer, an additive or similar may also be contained in the spinning stock solution, depending on the intended use. Examples of additives include boric acid, a surfactant, an antioxidant, a decomposition inhibitor, an antifreeze agent, a pH modifier, a masking agent, a coloring agent, and an oily agent.

[0046] The solvent to be used in the curing bath can be selected appropriately depending on the types of solvent used in the spinning stock solution. When the spinning stock solution is an aqueous solution, such as the curing bath, an aqueous solution or an alkaline aqueous solution of an inorganic salt that has curing capacity for a PVA-based polymer (e.g., sodium sulfate, ammonium sulfate, sodium carbonate, sodium hydroxide) can be used. Petition 870240053156, dated 06 / 24 / 2024, page 24 / 57 21 / 44 used. When the spinning stock solution is a solution in an organic solvent, such as the curing bath, an organic solvent with curing capacity for a PVA-based polymer, including an alcohol such as methanol, ethanol, propanol and butanol, and a ketone such as acetone, methyl ethyl ketone and methyl isobutyl ketone, may be used.

[0047] In the present invention, PVA-based fibers produced by dry spinning or PVA-based fibers produced from a spinning stock solution containing water or an organic solvent, such as the solvent for wet spinning, are preferred from the point of view of fiber tensile strength.

[0048] In order to remove solvent from the spinning stock solution of a raw yarn cured by extraction, the raw yarn may be passed through an extraction bath or may be subjected to wet drawing simultaneously with extraction. In addition, the fibers may be dried, if necessary, after wet drawing, or may even be subjected to dry heat drawing. When drawing is carried out, the drawing may be carried out at a total tensile rate (i.e., the product of a tensile rate during wet drawing and a tensile rate after drying) of, for example, 5 to 25 times, preferably about 8 to 20 times.

[0049] As with alkali-resistant fibers (D), commercially available fibers may be used. Examples of commercially available fibers include: organic fibers, such as polyvinyl alcohol-based fibers manufactured by Kuraray Co., Ltd., polypropylene fibers manufactured by Daiwabo Co., Ltd., and nylon fibers manufactured by Toray Industries, Inc.; and inorganic fibers, such as glass fibers manufactured by Nippon Electric Glass Co., Ltd. and Taiheiyo Materials Corporation.

[0050] In one aspect of the present invention, the alkali-resistant fiber content (D) is preferably 0.1% by mass or more, more Petition 870240053156, dated 06 / 24 / 2024, page 25 / 57 22 / 44 preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and is preferably 5% by mass or less, more preferably 4% by mass or less, even more preferably 3% by mass or less, in relation to a total solids content in the layered sheet. When the alkali-resistant fiber content (D) is equal to or greater than the lower limit mentioned above and equal to or less than the upper limit mentioned above, greater bending strength and greater impact resistance can be achieved in the layered sheet produced. The alkali-resistant fiber content (D) in the layered sheet can be measured by the following procedure. First, the layered sheet is dried at 105 °C until the mass of the layered sheet reaches a constant value and then weighed (W1 (g)).Subsequently, the layered sheet is sprayed with a mortar, then water is added to the sprayed product, and the resulting mixture is filtered through a metal screen (e.g., a 55-mesh metal screen) to separate the alkali-resistant fibers (D) and the cellulose-based fibers (C) from a matrix. The alkali-resistant fibers (D) and the cellulose-based fibers (C) thus separated are dried at 105 °C until the mass of the dry product reaches a constant value, then the dry product is immersed in a copper oxide-ammonia solution for fiber differentiation (manufactured by Kishida Chemical Co., Ltd.) in order to remove the cellulose-based fibers (C), and the cellulose-based fibers (C) are dissolved in the solution, thus separating the alkali-resistant fibers (D) from the cellulose-based fibers (C).The alkali-resistant fibers (D) thus separated are dried at 105 °C until the mass of the dry product reaches a constant value, and the dry product is weighed (W2 (g)). The alkali-resistant fiber content (D) in the layered sheet is calculated according to the following formula: Petition 870240053156, dated 06 / 24 / 2024, page 26 / 57 23 / 44 (Alkali-resistant fiber content (D) in layered sheet) = (W2 / W1) x 100 (E) Other powder

[0051] The layered sheet formed in the present invention may also contain a powder, other than that of the aluminosilicate source (A), as another powder (E). Examples of other powder (E) include silica fume, calcium carbonate, bentonite and a calcium sulfate derivative (e.g., gypsum dihydrate, desulfurizing gypsum, α- or β-hemihydrate gypsum and anhydrous gypsum), and these substances may be used alone, or two or more of them may be used in combination. When the layered sheet contains silica fume, more excellent dimensional stability can be achieved in the layered sheet. Therefore, the use of silica fume is preferred.

[0052] When the layered sheet formed in the present invention contains the other powder (E), the content of the other powder (E) is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, particularly preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 13% by mass or less, even more preferably 10% by mass or less, particularly preferably 8% by mass or less, relative to a total solids content in the layered sheet. When the content is equal to or greater than the lower limit mentioned above and is equal to or less than the upper limit mentioned above, the effect mentioned above of adding the other powder (E) can be achieved. (F) Slag activator

[0053] The cured compound in the present invention may also contain a slag activator (F). When a slag activator (F) is added to the curable composition in the present invention, it may be produced Petition 870240053156, dated 06 / 24 / 2024, page 27 / 57 24 / 44 a cured compound with higher flexural strength. Examples of slag activator (F) include aluminum sulfate, calcium hydroxide, sodium sulfate, and sodium aluminate, and these substances may be used alone, or two or more of them may be used in combination. Among these substances, from the point of view that a cured compound with higher flexural strength can be produced, it is preferable that the cured compound contain at least one selected from the group consisting of aluminum sulfate, calcium hydroxide, and sodium aluminate.

[0054] When the cured compound in the present invention contains the slag activator (F), the content is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, particularly preferably 1.5% by mass or more, and is preferably 6% by mass or less, more preferably 5% by mass or less, even more preferably 4% by mass or less, relative to a total solids content in the cured composite. When the content is equal to or greater than the lower limit mentioned above and is equal to or less than the upper limit mentioned above, the effect, mentioned above, of the addition of slag activator (F) can be achieved.

[0055] The thickness of the layered sheet can be selected appropriately depending on the intended use and is generally 4 mm or more and 30 mm or less. When the layered sheet is used as, for example, a wall material, the thickness of the layered sheet is preferably 4 mm or more and 20 mm or less. When the layered sheet is used as a flooring material, the thickness of the layered sheet is preferably 8 mm or more and 30 mm or less. The thickness of the layered sheet can be measured by the method described in the “Examples” section below. Petition 870240053156, dated 06 / 24 / 2024, page 28 / 57 25 / 44

[0056] The apparent density of the layered sheet can be appropriately selected depending on the intended use and is generally 0.5 g / cm3 or more and 2.0 g / cm3 or less. The apparent density of the layered sheet is preferably 0.8 g / cm3 or more, more preferably 1.0 g / cm3 or more, and is preferably 1.8 g / cm3 or less, more preferably 1.6 g / cm3 or less. The apparent density of the layered sheet can be measured by the method described in the “Examples” section below.

[0057] The impact resistance of the layered sheet, measured according to JIS K 7111, is preferably 2 kJ / m2 or more, more preferably 2.5 kJ / m2 or more, even more preferably 3 kJ / m2 or more. The upper limit of impact resistance is not particularly limited. The impact resistance is generally 7 kJ / m2 or less. When the impact resistance is equal to or greater than the lower limit mentioned above, the breakage of the layered sheet due to the application of impacts when, for example, the layered sheet is used as wall material, can be avoided, and the breakage of the layered sheet, which is caused by a falling object or similar when the layered sheet is used as floor material, can be avoided.

[0058] The bending strength of the sheet formed in layers, measured according to JIS A 1408, is preferably 10 N / mm2 or more, more preferably 11 N / mm2 or more, more preferably 12 N / mm2 or more, even more preferably 13 N / mm2 or more, particularly preferably 17 N / mm2 or more. The upper limit of bending strength is not particularly restricted. The bending strength is generally 35 N / mm2 or less. Method for manufacturing layered sheets

[0059] The layered sheet formed according to the present invention is preferably produced by a manufacturing method of Petition 870240053156, dated 06 / 24 / 2024, page 29 / 57 26 / 44 paper. The term “papermaking method” refers to a method in which a curable, pulp-type composition prepared by suspending a solid component, such as an aluminosilicate, and fibrous components, such as cellulose-based fibers (C) and alkali-resistant fibers (D) in an aqueous medium, is excavated with a screen and forms a solid material retained on the screen. Examples of papermaking methods include: a cylinder-type method or a Fourdrinier-type method, in which solid materials, each having a thin sheet-like shape, are sequentially rolled to produce a layered sheet of the desired thickness; and a flowon-type method, in which a certain thickness is ensured by one or more cycles of papermaking procedures using a dense curable composition.In the papermaking method, layered sheets can be mass-produced in a mechanical batch mode and continuously, and the layered sheets produced can have uniform and stable performance. Furthermore, it is generally possible to produce a relatively thin sheet with a thickness of about 2 to 30 mm. Producing a relatively thin sheet is extremely difficult using a production method other than the papermaking method (e.g., a casting method).

[0060] The layered sheet formed according to the present invention can be produced, for example, by a method comprising: a step to mix the aluminosilicate source (A), the alkali metal hydroxide (B), the cellulose-based fibers (C), the alkali-resistant fibers other than cellulose-based fibers (D), and water, together to prepare a curable composition; a step in producing formed sheets using curable composition by a papermaking method; and Petition 870240053156, dated 06 / 24 / 2024, page 30 / 57 27 / 44 a lamination step of two or more sheets formed one on top of the other.

[0061] When the other powder (E) and slag activator (F), which can be used as needed, are used, these optional components can be added in the first mixing step to mix the aluminosilicate source (A), the alkali metal hydroxide (B), the cellulose-based fibers (C), the alkali-resistant fibers other than cellulose-based fibers (D) and water together.

[0062] As the aluminosilicate source (A), the alkali metal hydroxide (B), the cellulose-based fibers (C) and the alkali-resistant fibers other than cellulose-based fibers (D) that are used in the production method, and the other powder (E) and the slag activator (F), which may be used as needed, the substances mentioned above in sections (A) Aluminosilicate source, (B) Alkali metal hydroxide, (C) Cellulose-based fibers, (D) Alkali-resistant fibers other than cellulose-based fibers, (E) Other powder and (F) Slag activator may be used.

[0063] The preparation method to be used in the preparation step of the curable composition is not particularly limited. From the point of view that a curable composition can be produced in which the solid components are uniformly dispersed, it is preferable to load and agitate the cellulose-based fibers (C) in a stirrer with water introduced into it, then add and agitate the aluminosilicate (A), the alkali metal hydroxide (B) and, optionally, the other powder (E) and the slag activator (F), and lastly add the alkali-resistant fibers (D). The order of addition of components (A) and (B) and of the optional components (E) and (F) is not particularly limited. The amount of water is not particularly limited. From the point of view that a uniform curable composition can be obtained without adding an excessive amount of water to the curable composition, the concentration of material Petition 870240053156, dated 06 / 24 / 2024, page 31 / 57 28 / 44 solid in the preparation step of the curable composition is generally 10% by mass or more and 25% by mass or less.

[0064] As for the papermaking method, one can use a cylinder-type, a Fourdrinier-type, or a flow-on-type. From the point of view that it is possible to produce layered sheets with a wide variety of thicknesses ranging from a thinner to a thicker thickness, the cylinder-type is preferably used. Therefore, in a preferred aspect of the present invention, the step for producing the sheet formed by the papermaking method comprises excavating the curable composition with a cylindrical wire.

[0065] In the cylinder-type method, the concentration of solid material in the preparation step of the curable composition is generally 10% by mass or more and 25% by mass or less. The prepared curable composition is diluted with process circulating water to a solid material concentration of generally 3% by mass or more and 10% by mass or less, and the diluted curable composition is fed to the cylinder screen and excavated into a formed sheet. In the cylinder-type method, the excavated solid material with a single cylinder screen, or two to six contiguous cylinder screens, is adhered to the felt to produce a formed sheet, and the formed sheet is rolled to a desired thickness while being rolled with a manufacturing roll. Therefore, continuous production is possible. As for the procedures and conditions to be used in the cylinder-type method, commonly used procedures and conditions can be employed.

[0066] In the production method, two or more formed sheets produced by the papermaking method are laminated. The formed sheet is laminated with a manufacturing roll until a desired thickness is achieved, and the laminated product is subjected to a dewatering, curing, and drying press to produce the formed sheet in layers. The pressure to be used in the dewatering press is Petition 870240053156, dated 06 / 24 / 2024, page 32 / 57 29 / 44 generally from 20 kg / cm2 to 300 kg / cm2, and the pressurization holding time is generally from 10 to 60 minutes. Curing is generally carried out under conditions that include a temperature of 50 °C to 90 °C and a relative humidity of 80% to 100% for 8 to 55 hours.

[0067] The drying method is not particularly limited, provided that a uniformly dry layered sheet can be produced. In general, the equilibrium moisture content (i.e., the moisture and water content in the layered sheet when the layered sheet is stored in a well-ventilated space for 7 days) of the layered sheet is about 6% to about 10%. Therefore, the layered sheet is dried in such a way that a water content at the same level as the equilibrium moisture content is achieved. The water content and equilibrium moisture content of the layered sheet can be measured simply using a Kett moisture meter.Alternatively, the water content and equilibrium moisture content can also be measured by weighing the layered sheet (W3) after drying, then weighing the layered sheet that is dried at 105 °C with an air dryer fitted with a stirrer until the mass of the layered sheet becomes a constant value (W4), and then performing the calculation according to the following formula. {(W3-W4) / W4}*100

[0068] The layered sheet produced by the above method is derived from a curable composition with excellent uniformity due to a specified composition and therefore the layered sheet can have all of: high flexural strength, high impact strength and high dimensional stability. EXAMPLES

[0069] The present invention will be explained in more detail by means of Examples and Comparative Examples. However, the present Petition 870240053156, dated 06 / 24 / 2024, page 33 / 57 30 / 44 The invention is not limited to these Examples. The properties in the Examples and Comparative Examples were measured or evaluated by the following methods. Thickness measurement

[0070] The thickness of a layered sheet to be measured was measured at 6 locations using Venier digital calipers, and an average of the measurement values ​​was defined as the thickness of the layered sheet. Method for measuring apparent density

[0071] An apparent density was measured in accordance with JIS A 5430. More specifically, a layered sheet to be measured was placed in an air dryer equipped with a stirrer and then dried at 105°C ± 5°C for 24 hours, and the apparent density was determined from the mass and volume of the layered sheet. Method for measuring bending strength

[0072] Four strip samples, each approximately 180 mm long and approximately 50 mm wide, were cut from a layered sheet for measurement. Subsequently, in order to adjust the water content in each sample at the time of measurement to a constant value, the samples were dried in an air dryer equipped with a stirrer at a temperature of 40 °C for 72 hours. The bending strength of each sample was measured according to JIS A 1408, and an average of the measured values ​​was used as the bending strength. The bending strength was measured using the “AG500-B” autograph, manufactured by Shimadzu Corporation, in a center loading mode under conditions including a bending span of 14.6 cm and a test speed (loading head speed) of 20 mm / min. Method for measuring impact resistance Petition 870240053156, dated 06 / 24 / 2024, page 34 / 57 31 / 44

[0073] Six strip samples, each approximately 80 mm long and approximately 10 mm wide, were cut from a layered sheet for measurement. Subsequently, in order to adjust the water content in each sample at the time of measurement to a constant value, the samples were dried in an air dryer equipped with a stirrer at a temperature of 40 °C for 72 hours. The impact resistance of each sample was measured according to JIS K 7111 “Test method for plastics - Charpy impact resistance”, and an average of the measurement values ​​was used as the impact resistance. The impact resistance was measured using a Charpy impact testing machine (digital), model “DG-CB”, manufactured by Toyo Seiki Seisaku-sho, Ltd. Method for measuring the rate of dimensional change

[0074] The rate of dimensional change of a sheet formed in layers was measured in accordance with JIS A 5430.

[0075] First, a layered sheet to be measured was placed in a dryer, then the dryer temperature was maintained at 60°C±3°C for 24 hours, and then the layered sheet was removed from the dryer. The removed layered sheet was placed in a desiccator that had been moistened with silica gel, and then left to stand until the temperature reached 20±1.5°C. Subsequently, a milky glass was glued onto the layered sheet, then calibration lines were notched in such a way that the distance between the calibration lines became approximately 140 mm, then the length between the calibration lines was measured with a comparator with an accuracy of 1 / 500 mm, and the measured length was defined as Li (mm). Subsequently, the layered sheet was placed at the end in such a way that the direction of the length of the layered sheet became Petition 870240053156, dated 06 / 24 / 2024, page 35 / 57 32 / 44 horizontal and then the layered sheet was immersed in water at 20°C ± 1.5°C, such that the upper end of the layered sheet was located approximately 30 mm below the water surface. After 24 hours, the layered sheet was removed from the water, the water adhering to the layered sheet was washed off, then the length between the calibration lines was measured again, and the measured length was defined as L2 (mm). The dimensional change ratio Y (%) due to water absorption was calculated according to the following formula. Rate of change of length due to water absorption Y ={(L2-Li) / Li}x100 Example 1

[0076] The pulp (NBKP, “Cellofiber” manufactured by PALTEK Corporation) (3% by mass) that served as cellulose-based fibers (C) was dispersed in water. The resulting dispersion was mixed with blast furnace slag (specific surface area: 4000 cm2 / g) (80.5% by mass) and fly ash (“Yonden fly ash type-II”: manufactured by Yonden Business Co., Inc.) (5% by mass), which served as sources of aluminosilicate (A), slaked lime (“Industrial slaked lime No. 1”: manufactured by Kochi Sekkai Kogyou) (5% by mass) which served as alkali metal hydroxide (B), and silica fume (“EFACO silica fume”: manufactured by Tomoe Engineering Co., Ltd.) (5% by mass) which served as the other powder (E) with a mixer. PVA1 (manufactured by Kuraray Co., Ltd.) (1.5% by mass) was added to the resulting mixture, which served as alkali-resistant fibers (D).The resulting mixture was further stirred to produce a curable paste-type composition with a solid material concentration of 16% by mass. The curable composition was transferred to a constant feed apparatus. Subsequently, the paste was fed from a feed tank into the constant feed apparatus to a roller screen process. Petition 870240053156, dated 06 / 24 / 2024, pp. 36 / 57 33 / 44 Subsequently, the concentration of solid material in the pulp was adjusted to 4% by mass with process circulation water, and the resulting product was subjected to a papermaking procedure using the Mini Hatschek machine. Following this, a formed sheet produced in the cylinder screen process was laid out in 10 layers with a manufacturing roll, and the formed sheet, which was in a wet condition, was pressed for 20 minutes applying a pressure of 75 kg / cm² to squeeze out a liquid component. The sheet formed after compression of the liquid component had a thickness of 4.6 mm and an apparent density of 1.35 g / cm³.The formed sheet was placed in a constant temperature / constant humidity curing apparatus and then cured under conditions that included a temperature of 90°C and a saturated humidity (RH of 98%) for 48 hours, and was then dried in an air dryer equipped with an agitator at 60°C for 16 hours, to produce a layered formed sheet.

[0077] The layered sheet thus produced was subjected to evaluation in the ways mentioned above. The results are shown in Table 2. Examples 2 to 4

[0078] Layered sheets were produced and evaluated in the same manner as in Example 1, except that the blast furnace slag content ratio and the alkali metal hydroxide (B) content ratio were altered, as shown in Table 2. Examples 5 to 7

[0079] Layered sheets were produced and evaluated in the same manner as in Example 3, except that the types of alkali-resistant fibers other than cellulose-based fibers (D) were changed as shown in Table 2. Example 8 Petition 870240053156, dated 06 / 24 / 2024, pp. 37 / 57 34 / 44

[0080] A layered sheet was produced and evaluated in the same manner as in Example 2, except that a blast furnace slag having a specific surface area of ​​6,000 cm2 / g was used instead of a blast furnace slag having a specific surface area of ​​4,000 cm2 / g. Example 9

[0081] A layered sheet was produced and evaluated in the same manner as in Example 3, except that a blast furnace slag having a specific surface area of ​​6,000 cm² / g was used instead of a blast furnace slag having a specific surface area of ​​4,000 cm² / g, and PVA2 was used instead of PVA1. Examples 10 to 11

[0082] Layered sheets were produced and evaluated in the same manner as in Example 9, except that the blast furnace slag content ratio and fly ash content ratio were altered as shown in Table 2. Examples 12 to 13

[0083] Layered sheets were produced and evaluated in the same manner as in Example 11, except that the blast furnace slag content ratio and the silica fume content ratio were altered as shown in Table 2. Example 14

[0084] A layered sheet was produced and evaluated in the same manner as in Example 3, except that the blast furnace slag content ratio and the pulp content ratio were altered as shown in Table 2. Example 15

[0085] A layered sheet was produced and evaluated in the same manner as in Example 6, except that the blast furnace slag content ratio and the alkali-resistant fiber content ratio were different from Petition 870240053156, dated 06 / 24 / 2024, pp. 38 / 57 35 / 44 cellulose-based fibers (D) were altered as shown in Table 2. Example 16

[0086] A layered sheet was produced and evaluated in the same manner as in Example 1, except that silica fume and gypsum dihydrate were added in place of silica fume as the other powder (E), and the blast furnace slag content ratio and the alkali metal hydroxide content ratio (B) were altered as shown in Table 2. Example 17

[0087] A layered sheet was produced and evaluated in the same manner as in Example 1, except that the blast furnace slag content ratio and the alkali metal hydroxide content ratio (B) were altered as shown in Table 2, and the cellulose-based fiber dispersion (C) was mixed with blast furnace slag and fly ash which served as sources of aluminosilicate (A), slaked lime which served as alkali metal hydroxide (B), and silica fume which served as the other powder (E), and aluminum sulfate which served as a slag activator (F) with a mixer, instead, the cellulose-based fiber dispersion (C) was mixed with blast furnace slag and fly ash which served as sources of aluminosilicate (A), slaked lime which served as alkali metal hydroxide (B) and silica fume which served as the other powder (E) with a mixer. Examples 18 to 19

[0088] Layered sheets were produced and evaluated in the same manner as in Example 2, except that silica fume and gypsum dihydrate were added in place of silica fume as the other powder (E), and the blast furnace slag content rate and the types of alkali-resistant fibers other than cellulose-based fibers (D) were changed as shown in Table 2. Examples 20 to 21 Petition 870240053156, dated 06 / 24 / 2024, pp. 39 / 57 36 / 44

[0089] Layered sheets were produced and evaluated in the same manner as in Example 17, except that silica fume and gypsum dihydrate were added in place of silica fume as the other powder (E), the blast furnace slag content rate, the alkali metal hydroxide content rate (B), and the slag activator content rate (F) were changed as shown in Table 2, and the temperature and curing time were changed from 90°C and 48 hours to 60°C and 24 hours. Example 22

[0090] A layered sheet was produced and evaluated in the same manner as in Example 1, except that fly ash and red mud were added in place of fly ash, and the blast furnace slag content ratio and fly ash content ratio were altered as shown in Table 2. Example 23

[0091] A layered sheet was produced and evaluated in the same manner as in Example 4, except that fly ash and red mud were added in place of fly ash, and the blast furnace slag content ratio, fly ash content ratio, and silica fume content ratio were altered as shown in Table 2. Example 24

[0092] A layered sheet was produced and evaluated in the same manner as in Example 8, except that the blast furnace slag content rate was changed from 75.5 wt% to 56 wt% and, due to this change, the fly ash content rate and the alkali metal hydroxide (B) content rate were also changed, as shown in Table 2. Comparative Example 1

[0093] An attempt was made to produce a sheet formed in the same way as in Example 1, except that the metal hydroxide Petition 870240053156, dated 06 / 24 / 2024, pp. 40 / 57 37 / 44 alkaline (B) was not added and, due to this change, the blast furnace slag content rate was altered, as shown in Table 2. However, the composition was not cured. Consequently, the evaluation of a layered sheet could not be performed. Comparative Example 2

[0094] A layered sheet was produced and evaluated in the same manner as in Example 3, except that alkali-resistant fibers other than cellulose-based fibers (D) were not added and, due to this change, the blast furnace slag content rate was altered as shown in Table 2. Comparative Example 3

[0095] A layered sheet was produced and evaluated in the same manner as in Example 1, except that the blast furnace slag content rate was changed from 80.5 wt% to 55 wt% and, due to this change, the alkali metal hydroxide content rate (B), the cellulose-based fiber content (C) and the content rate of alkali-resistant fibers other than cellulose-based fibers (D) were also changed, as shown in Table 2. Comparative Example 4

[0096] A layered sheet was produced and evaluated in the same manner as in Example 3, except that a blast furnace slag having a specific surface area of ​​800 cm2 / g was used instead of blast furnace slag having a specific surface area of ​​4000 cm2 / g. Comparative Example 5

[0097] A layered sheet was produced and evaluated in the same manner as in Example 3, except that a blast furnace slag having a specific surface area of ​​10,000 cm2 / g was used instead of blast furnace slag having a specific surface area of ​​4,000 cm2 / g. Petition 870240053156, dated 06 / 24 / 2024, pp. 41 / 57 38 / 44 Comparative Example 6

[0098] A layered sheet was produced and evaluated in the same manner as in Example 1, except that the blast furnace slag content rate was changed from 80.5 wt% to 90.5 wt%, and the fly ash content rate and the silica fume content rate were changed as shown in Table 2.

[0099] The properties of the fibers used in the Examples and Comparative Examples are shown in Table 1 below. Table 2 presents the compositions used in the Examples and Comparative Examples, and the results of the evaluation of the layered sheets produced in the Examples and Comparative Examples. Table 1

[0100] Table 1: Fiber properties Fineness (dtex) Average fiber diameter (pm) Average fiber length (mm) Elongation ratio PVA 1 Polyvinyl alcohol-based fiber manufactured by Kuraray Co., Ltd. 0.5 7.0 4 571 PVA 2 Polyvinyl alcohol-based fiber manufactured by Kuraray Co., Ltd. 2.0 14.0 6 429 PVA 3 Polyvinyl alcohol-based fiber manufactured by Kuraray Co., Ltd. 4.0 20.0 6 300 PVA 4 Polyvinyl alcohol-based fiber manufactured by Kuraray Co., Ltd. 7.0 26.0 6 231 PP Polypropylene fibers manufactured by Daiwabo Co., Ltd. 2.2 17.0 6 353 Petition 870240053156, dated 06 / 24 / 2024, pp. 42 / 57 Table 2 Table 2: Compositions in the Examples and Comparative Examples, and results of the evaluation of layered sheets produced in the Examples and Comparative Examples. Source of aluminosilicate (A) Alkali metal hydroxide (B) Cellulose-based fibers (C) Alkali-resistant fibers, except cellulose-based fibers (C)(D) Other powder (E) Slag activator (F) Thickness (mm) Specific gravity by mass (g / cm3) Flexural strength (N / mm2) Impact strength (kJ / m2) Rate of dimensional change (%) Blast furnace slag Fly ash (% by mass) Red mud(% by mass) Slaked lime (% by mass) Pulp (% by mass) Type (% by mass) Active silica (% by mass) Gypsum dihydrate (% by mass) Aluminum sulfate (% by mass) Specific surface area (cm² / g) (% by mass) Example 1 4000 80.5 5 - 5 3 PVA1 1.5 5 - - 4.6 1.35 15.0 4.20 0.117 Example 2 4000 75.5 5 - 10 3 PVA1 1.5 5 - - 4.7 1.34 16.6 4.33 0.123 Example 3 4000 71 5 - 14.5 3 PVA1 1.5 5 - - 4.7 1.32 20.4 3.42 0.127 Example 4 4000 65.5 5 - 20 3 PVA1 1.5 5 - - 4.6 1.38 23.1 3.59 0.155 Example 5 4000 71 5 - 14.5 3 PVA3 1.5 5 - - 4.6 1.36 19.6 3.44 0.138 Example 6 4000 71 5 - 14.5 3 PVA4 1.5 5 - - 4.8 1.39 19.2 3.51 0.119 Example 7 4000 71 5 - 14.5 3 PP 1.5 5 - - 4.8 1.36 14.3 3.67 0.143 Example 8 6000 75.5 Example 9: 6000 71 5 - 14.5 3 PVA2 1.5 5 - 4.8 1.31 20.4 4.38 0.099 Example 10: 6000 66 10 - 14.5 3 PVA2 1.5 5 - - 4.8 1.30 18.3 4.26 0.113. 39 / 44 Petition 870240053156, dated 06 / 24 / 2024, pp. 43 / 57 Example 11 6000 76 - - 14.5 3 PVA2 1.5 5 - 4.7 1.32 20.1 3.71 0.127 Example 12 6000 81 - - 14.5 3 PVA2 1.5 - - 4.6 1.34 21.3 3.73 0.146 Example 13 6000 71 - - 14.5 3 PVA2 1.5 10 - - 4.9 1.30 19.8 3.55 0.118 Example 14 4000 65 5 - 14.5 9 PVA1 1.5 5 - - 5.3 1.25 21.9 3.97 0.143 Example 15 4000 68.5 5 - Example 16: 4000 68 5 - 14.5 3 PVA1 1.5 5 3 - 4.7 1.31 20.1 3.54 0.129 Example 17: 4000 68 5 - 14.5 3 PVA1 1.5 5 - 3 4.7 1.34 21.2 3.46 0.139 Example 18: 4000 69.5 5 - 10 3 PVA2 1.5 5 6 - 4.3 1.37 23.0 3.06 0.148 Example 19: 4000 66.5 5 - 10 3 PVA2 Example 20: 4000 65.0 5 - 7 3 PVA1 1.5 5 10.2 3.3 5.7 1.51 33.0 3.03 0.180 Example 21: 4000 56.0 5 - 7 3 PVA1 1.5 5 19.2 3.3 5.8 1.49 31.4 3.35 0.162 Example 22: 4000 57.5 5 23 5 3 PVA1 1.5 5 - - 4.6 1.38 20.1 4.43 0.103 Example 23: 4000 58 5 12.5 20 3 PVA1 1.5 - - - 4.7 1.40 21.4 4.21 0.100 Example 24 6000 56 20 - 14.5 3 PVA1 1.5 5 - - 4.8 1.25 16.8 3.06 0.171 40 / 44 Petition 870240053156, dated 06 / 24 / 2024, pp. 44 / 57 Table 3 Continuation of Table 2 Source of aluminosilicate (A) Alkali metal hydroxide (B) Cellulose-based fibers (C) Alkali-resistant fibers, except cellulose-based fibers (C) (D) Other powder (E) Slag activator (F) Thickness (mm) Specific gravity by mass (g / cm3) Flexural strength (N / mm2) Impact strength (kJ / m2) Rate of dimensional change (%) Blast furnace slag Fly ash (% by mass) Red mud (% by mass) Slaked lime (% by mass) Pulp (% by mass) Type (% by mass) Silica fume (% by mass) Gypsum dihydrate (% by mass) Aluminum sulfate (% by mass) Specific surface area (cm2 / g) (% by mass) Example Comparative 1 4000 85.5 5 - - 3 PVA1 1.5 5 - - Uncured Comparative Example 2 4000 72.5 5 - 14.5 3 - - 5 - - 4.3 1.40 10.8 1.26 0.138 Comparative Example 3 4000 55 5 - 20 10 PVA1 5 5 - - 5.4 1.22 16.4 1.87 0.238 Example 800 71 5 - 14.5 3 PVA1 1.5 5 - - 4.6 1.36 6.2 1.35 0.183 41 / 44 Petition 870240053156, dated 06 / 24 / 2024, pp. 45 / 57 Comparative Example 4 Comparative Example 5 10000 71 5 - 14.5 3 PVA1 1.5 Comparative Example 6 4000 90.5 - - 5 3 PVA1 1.5 5 - - 4.5 1.31 12.6 1.53 0.162 - - - 4.3 1.41 11.4 2.04 0.194 42 / 44 Petition 870240053156, dated 06 / 24 / 2024, pp. 46 / 57 43 / 44

[0101] All layered sheets produced in Examples 1 through 24 exhibited high flexural strength, high impact resistance, and high dimensional stability.

[0102] On the other hand, the layered sheet produced in Comparative Example 2, in which alkali-resistant fibers (D) were not added, showed remarkably weak flexural strength and remarkably weak impact strength.

[0103] The layered sheet produced in Comparative Example 3, in which the blast furnace slag content with a specific surface area of ​​1000 cm2 / g or more and 9000 cm2 / g or less was 55% by mass or less relative to a total solids content in the curable composition, showed remarkably weak impact resistance and a remarkably high dimensional change rate.

[0104] The layered sheet produced in Comparative Example 4, in which blast furnace slag with a specific surface area of ​​less than 1000 cm2 / g was contained in an amount of 60 % by mass or more relative to a total solids content in the curable composition, showed remarkably weak flexural strength, remarkably weak impact strength and a high rate of dimensional change.

[0105] The layered sheet produced in Comparative Example 5, in which blast furnace slag with a specific surface area greater than 9000 cm2 / g was contained in an amount of 60 % by mass or more relative to a total solids content in the curable composition, showed remarkably weak flexural strength, remarkably weak impact strength and a high rate of dimensional change.

[0106] The layered sheet produced in Comparative Example 6, in which the blast furnace slag content with a super area Petition 870240053156, dated 06 / 24 / 2024, pp. 47 / 57 44 / 44 specific surface area of ​​1000 cm2 / g or more and 9000 cm2 / g or less was greater than 90% by mass relative to the total solids content in the curable composition, showed remarkably weak flexural strength and a high rate of dimensional change. INDUSTRIAL APPLICABILITY

[0107] The layered sheet formed according to the present invention has high flexural strength, high impact resistance and high dimensional stability. Therefore, the layered sheet formed according to the present invention can be usefully used as various architectural materials, such as, but not particularly limited to, an interior material, an exterior material, a flooring material, a wall material, a ceiling lining material, a partition material, a roofing material and a roofing material.

Claims

1. Layered sheet, characterized in that it comprises: two or more formed sheets, each formed from a curable composition comprising: (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) other alkali-resistant fibers other than cellulose-based fibers, wherein the aluminosilicate source (A) comprises blast furnace slag, and the blast furnace slag content has a specific surface area of ​​1,000 cm² / g or more and 9,000 cm² / g or less, which is greater than 55% by mass and 90% by mass or less, relative to a total solids content in the curable composition, wherein the alkali metal hydroxide (B) is slaked lime, wherein the layered sheet comprises silica fume as other powder (E), and the content of other powder (E) is 1% in mass or more and 13% or less by weight relative to the total solid content in the layered sheet.

2. Layered sheet, characterized in that it comprises: two or more formed sheets, each formed from a curable composition comprising: (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) other alkali-resistant fibers other than cellulose-based fibers, wherein the aluminosilicate source (A) comprises blast furnace slag, and the blast furnace slag content having a specific surface area of ​​1,000 cm² / g or more and 9,000 cm² / g or less is greater than 55% by mass and 90% by mass or less, relative to the total solids content in the curable composition, and Petition 870260041383, dated 04 / 05 / 2026, p. 6 / 22 2 / 5 wherein the alkali metal hydroxide (B) content is 3% by mass or more and 45% by mass or less, relative to a total solids content in the curable composition.

3. Layered sheet, according to claim 1 or 2, characterized in that the cellulose (C) fiber content is 0.5% by mass or more and 15% by mass or less, relative to the total solids content in the layered sheet.

4. Layered sheet, according to any one of claims 1 to 3, characterized in that the content of alkali-resistant fibers other than cellulose-based fibers (D) is 0.1% by mass or more and 5% by mass or less, relative to a total solids content in the layered sheet.

5. Layered sheet, according to any one of claims 1 to 4, characterized in that the aluminosilicate source (A) further contains at least one selected from the group consisting of fly ash, metakaolin and red mud in a content of 1% by mass or more and 35% by mass or less, relative to a total solids content in the curable composition.

6. Layered sheet, according to any one of claims 1 to 5, characterized in that the cellulose (C)-based fibers are pulps.

7. Layered sheet, according to any one of claims 1 to 6, characterized in that the alkali-resistant fibers other than cellulose-based fibers (D) have an average fiber diameter of 100 μm or less, and an elongation ratio of 50 or more and 2000 or less.

8. Layered sheet, according to any one of claims 1 to 7, characterized in that the alkali-resistant fibers other than cellulose-based fibers (D) are, by Petition 870260041383, dated 04 / 05 / 2026, page 7 / 22 3 / 5, less than one type of fiber selected from the group consisting of polyvinyl alcohol-based fibers, polyethylene fibers, polypropylene fibers, acrylic fibers, aramid fibers and nylon fibers.

9. Layered sheet according to any one of claims 1 to 8, characterized in that the impact resistance of the layered sheet is 2 kJ / m2 or more, as measured in accordance with JIS K 7111.

10. Method for manufacturing a layered formed sheet, as defined in any one of claims 1 to 9, characterized in that it comprises: a step for mixing (A) an aluminosilicate source, (B) an alkali metal hydroxide being slaked lime, (C) cellulose-based fibers, (D) alkali-resistant fibers other than cellulose-based fibers, water and other powder (E), together to prepare a curable composition; a step for producing a formed sheet by a papermaking method using the curable composition; and a step for laminating two or more formed sheets one on top of the other.

11. Method for manufacturing a layered formed sheet, as defined in any one of claims 1 to 10, characterized in that it comprises: a step for mixing (A) an aluminosilicate source, (B) an alkali metal hydroxide being slaked lime, (C) cellulose-based fibers, (D) alkali-resistant fibers other than cellulose-based fibers, water and other powder (E), together to prepare a curable composition; a step for producing a formed sheet by a papermaking method using the curable composition; and a step for laminating two or more formed sheets one on top of the other, wherein the step for producing the formed sheet by the papermaking method comprises excavating the curable composition with a cylindrical wire.

12. Invention, defined by any form of its embodiments or any category of claim that may be claimed, for example, product, or process, or use covered by the object initially described, disclosed, or illustrated in the patent application, including: and / or Layered sheet comprising two or more formed sheets, each formed from a curable composition comprising (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) alkali-resistant fibers other than cellulose-based fibers; and / or Layered sheet comprising two or more formed sheets, each formed from a curable composition comprising (E) a powder, which includes silica fume, calcium carbonate, bentonite and a calcium sulfate derivative, and these substances may be used individually, or two or more of them may be used in combination;and / or Method for manufacturing a layered sheet comprising: a step for mixing (A) the aluminosilicate source, (B) the alkali metal hydroxide, (C) the cellulose-based fibers, (D) alkali-resistant fibers other than cellulose-based fibers and water, together to prepare a curable composition; a step for producing sheets formed using the composition Petition 870260041383, dated 04 / 05 / 2026, page 9 / 22 5 / 5 curable by a papermaking method; and a step for laminating two or more sheets formed one on top of the other; and / or Curable composition comprising (A) an aluminosilicate source, (B) an alkali metal hydroxide, (C) cellulose-based fibers, and (D) alkali-resistant fibers other than cellulose-based fibers;and / or Product comprising a sheet formed in layers as defined in any of the preceding claims or in any part of the patent application, or a composition as defined in any of the preceding claims or in any part of the patent application and one or more additional agents. Petition 870260041383, dated 04 / 05 / 2026, page 10 / 22;