Fiber-reinforced inorganic molded body, and method of producing the same

Abstract

To provide a fiber-reinforced inorganic molded body in which deterioration caused by an alkali present in a reinforcing fiber of poor alkali resistance such as E glass is suppressed even when a geopolymer is used as a matrix material and the reinforcing fiber is used as a material of a fiber base-material, and a method of producing the same.SOLUTION: The present invention in one aspect relates to a fiber-reinforced inorganic molded body including a reinforcing layer. The reinforcing layer includes a fiber base-material including a reinforcing fiber, and a geopolymer as a matrix resin. The active filler included in the raw material of the geopolymer is metakaolin having an electric conductivity difference of 1.5 mS / cm or larger and 2.1 mS / cm or smaller, and the reinforcing fiber is at least one kind of fibers selected from glass fibers (excluding an alkali-resistant fiber) and basalt fibers. The glass fiber preferably is an E-glass fiber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced inorganic molded article and a method for producing the same. [Background technology]

[0002] Panels and monuments installed on the walls of buildings are often installed high above ground level, so they must be lightweight and strong. Fiber-reinforced plastics can be used to reduce the weight of the molded body while maintaining its strength, but they lack fire resistance. Fiber-reinforced concrete and fiber-reinforced gypsum are used when flame retardancy and fire resistance are required, but these are inferior to fiber-reinforced plastics in terms of lightness. Furthermore, gypsum cannot be used outdoors because it is not water-resistant, and it is also brittle. Glass fiber, on the other hand, is used in a wide range of applications due to its strength, non-flammability, heat resistance, electrical insulation, and chemical resistance.

[0003] Patent Document 1 discloses a fiber-reinforced inorganic molded body that includes a surface layer containing a hardened geopolymer and a reinforcing layer containing a fiber substrate and a geopolymer that has been impregnated into the fiber substrate and hardened. In this fiber-reinforced inorganic molded body, the matrix materials of the surface layer and the reinforcing layer are both hardened geopolymers, and the reinforcing fibers in the reinforcing layer are glass fibers or basalt fibers, making the molded body lightweight and non-flammable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-174741 Summary of the Invention [Problem to be solved by the invention]

[0005] Because geopolymers are alkaline materials, it has been thought that fibers with poor alkali resistance, such as reinforcing fibers made from E-glass, cannot be used as fiber substrate materials. On the other hand, ordinary glass fibers, such as E-glass fibers, are relatively inexpensive and are widely used as reinforcing fibers for FRP. Furthermore, commercially available fiber substrates come in a variety of forms, including mats and tapes, and the amount of binder used to bind the glass fibers together also varies. In other words, fiber substrates containing ordinary glass fibers, such as E-glass fibers, are both economical and easy to use.

[0006] Therefore, the present disclosure provides a fiber-reinforced inorganic molded body and a manufacturing method thereof, in which a geopolymer is used as a matrix material and deterioration of the reinforcing fiber due to alkali is suppressed even when a reinforcing fiber with poor alkali resistance, such as E-glass, is used as the fiber substrate material. [Means for solving the problem]

[0007] In one aspect, the present invention provides a fiber-reinforced inorganic molded body including a reinforcing layer, A fiber-reinforced inorganic molded body including a reinforcing layer, The reinforcing layer includes a fiber substrate containing reinforcing fibers and a geopolymer as a matrix resin, The active filler contained in the raw material of the geopolymer is metakaolin having an electrical conductivity difference of 1.5 mS / cm or more and 2.1 mS / cm or less, The present invention relates to a fiber-reinforced inorganic molded article, wherein the reinforcing fibers are at least one type of fiber selected from glass fibers (excluding alkali-resistant fibers) and basalt fibers.

[0008] In one aspect, the present disclosure provides a method for producing a fiber-reinforced inorganic molded body of the present disclosure, The method includes placing a plurality of sheets of the fiber substrate impregnated with the geopolymer composition in a mold, curing the sheets to harden them, and then demolding them. The geopolymer composition relates to a method for producing a fiber-reinforced inorganic molding, which comprises an alkaline silicate solution and the metakaolin having an electrical conductivity difference of 1.5 mS / cm or more and 2.1 mS / cm or less. [Effects of the Invention]

[0009] The present disclosure can provide a fiber-reinforced inorganic molding and a manufacturing method thereof in which deterioration of the reinforcing fiber due to alkali is suppressed even when a geopolymer is used as a matrix material and a reinforcing fiber with poor alkali resistance, such as E-glass, is used as a fiber substrate material. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view of a fiber-reinforced inorganic molded article according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic perspective view of a fiber-reinforced inorganic molded article according to one embodiment of the present disclosure. [Figure 3] FIG. 3 is a graph showing the relationship between the curing time (room temperature) and pH in the manufacturing process of the fiber-reinforced inorganic molded bodies of Examples 1 and 2 and Comparative Example 1. [Figure 4] FIG. 4 is a graph showing the changes over time in bending strength and pH of the fiber-reinforced inorganic molded body of Example 1 after a 80° C. hot water test. [Figure 5] FIG. 5 is a graph showing the change over time in pH of the fiber-reinforced inorganic molded bodies of Example 1 and Comparative Example 2 after a 80° C. hot water test. DETAILED DESCRIPTION OF THE INVENTION

[0011] In one aspect, the present disclosure relates to a fiber-reinforced inorganic molding comprising a fiber substrate containing reinforcing fibers and a geopolymer impregnated and cured into the fiber substrate. The geopolymer is an amorphous condensation polymer produced by reacting an alkaline silicate solution with an activated filler. Because geopolymers are alkaline, it has been common knowledge that ordinary glass fibers and basalt fibers, which are vulnerable to alkali, cannot be used as reinforcing fibers for fiber-reinforced inorganic moldings with a geopolymer matrix. On the other hand, ordinary glass fibers are widely used as reinforcing fibers for FRP because they are relatively inexpensive. Moreover, commercially available fiber substrates come in a variety of forms, such as mats and tapes, and the amount of binder used to bind the glass fibers varies. In other words, fiber substrates containing ordinary glass fibers, such as E-glass fibers, are economical and easy to use. The present disclosure is based on the new finding that, contrary to the above-mentioned common technical knowledge, the use of a specific metakaolin (aluminum-based active filler) as an active filler suppresses the alkali-induced deterioration of glass fibers and basalt fibers, thereby enabling the production of a fiber-reinforced inorganic molded body.

[0012] In the present disclosure, the mechanism by which the above effects are obtained is presumed to be as follows. As mentioned above, geopolymer is an amorphous condensation polymer (polymer) produced by the condensation polymerization reaction between an alkaline silicate solution and an active filler such as metakaolin. When the alkaline silicate solution and metakaolin are placed in a strong alkaline environment, silicate ions (monomers) are eluted from the alkaline silicate solution, and aluminate ions (monomers) are eluted from the metakaolin. These undergo a condensation polymerization reaction to produce an aluminosilicate framework. At this time, the framework is made up of Si 4+ Al against 3+ The substitution results in a negative charge overall, so Na + or K + of hydrated ions are incorporated into the framework. In the present disclosure, even when geopolymer is used as the matrix material and glass fiber or basalt fiber, which has poor alkali resistance, is used as the fiber base material, the deterioration (decrease in strength) of the fiber due to alkali is suppressed, contrary to the above-mentioned common technical knowledge. The reason for this is that the active filler is a specific metakaolin, which is able to suppress the alkali (Na + , K. + ) is quickly incorporated into the framework, and the alkali (Na + , K. + This is thought to be because the fixation of the alkali in the geopolymer occurs early during the curing process, and the pH also drops significantly early during the curing process and remains low thereafter.The degree of fiber deterioration due to alkali can be evaluated by the bending strength of the fiber-reinforced inorganic molding.

[0013] Metakaolin is white in color, and its composition is over 90% aluminosilicate (aluminum silicate), with the remainder being impurities. Metakaolin is characterized by its high content of titanium oxide as an impurity. Therefore, the use of metakaolin as an active filler in geopolymers can be determined by composition analysis using X-ray fluorescence analysis and amorphous analysis using X-ray diffraction. Fly ash, which is often used as an active filler for producing geopolymers, is black in color because it contains a lot of iron and carbon.

[0014] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the drawings, but the present invention is not limited to those shown in the drawings.

[0015] [Fiber-reinforced inorganic molding] FIG. 1 is a schematic perspective view illustrating a fiber-reinforced inorganic molded body according to one embodiment of the present disclosure, and FIG. 2 is a schematic perspective view illustrating a fiber-reinforced inorganic molded body according to another embodiment of the present disclosure. As shown in FIGS. 1 and 2, the fiber-reinforced inorganic molded body 1 includes a fiber substrate 6 containing reinforcing fibers and a reinforcing layer 5 containing a geopolymer 7 impregnated into the fiber substrate 6 and cured. In this disclosure, geopolymer 7 is a general term for an amorphous condensation polymer (hardened body) formed by the reaction of metakaolin as an active filler with an alkali silicate solution. Unlike cement, geopolymer 7 is not a hydrate produced by reaction with water. Therefore, geopolymer 7 does not break bonds even at high temperatures. Its strong inorganic polymer structure makes it resistant to degradation factors such as wind, rain, solar radiation, acid, and temperature changes.

[0016] [Alkaline silicate solution] The alkali silicate solution is an aqueous solution of an alkali metal silicate, and the silicate is preferably at least one selected from the group consisting of sodium silicate, potassium silicate, and lithium silicate, more preferably potassium silicate, and even more preferably potassium silicate. The aqueous solution of an alkali metal silicate can also be prepared by mixing an alkali metal hydroxide, amorphous silica, and water.

[0017] [Metakaolin] The present invention is characterized by using metakaolin with a specific electrical conductivity difference as the raw material for the geopolymer that constitutes the fiber-reinforced inorganic molded body 1. The electrical conductivity difference of the metakaolin is 1.5 mS / cm or more, preferably 1.7 mS / cm or more, from the viewpoint of improving the alkali resistance and strength of the fiber-reinforced inorganic molded body 1, and is preferably 2.1 mS / cm or less, from the viewpoint of ensuring the usable life of the molding material. The difference in electrical conductivity of metakaolin is an index related to the reactivity of pozzolanic active substances induced by alkaline substances, known as the Luxan method. The difference in electrical conductivity is obtained as follows: According to "Cement Concrete Research, Vol. 19, pp. 63-68, 1989," the electrical conductivity of 200 ml of saturated Ca(OH)2 aqueous solution is measured at 40±1°C. Next, 5 g of metakaolin is added to the saturated Ca(OH)2 aqueous solution, and the solution is stirred and the electrical conductivity is measured after 2 minutes. The difference between the electrical conductivity before and after the addition of metakaolin is the electrical conductivity difference.

[0018] From the viewpoint of improving the alkali resistance and strength of the fiber-reinforced inorganic molded body 1, the average particle size of the metakaolin is preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less, and even more preferably 2 μm or more and 5 μm or less. By using metakaolin with a small average particle size, in other words, a large surface area, the condensation polymerization reaction proceeds quickly, and the alkali (Na + , K. + This is because the fixation of metakaolin in the geopolymer occurs earlier and the pH also drops significantly at an earlier stage.In this application, the average particle size of metakaolin is the median diameter (D50) measured using a particle size distribution analyzer based on the measurement principle of laser light diffraction and scattering.

[0019] [Fiber base material] The reinforcing fibers constituting the fiber substrate are at least one type of fiber selected from glass fibers (excluding alkali-resistant fibers) and basalt fibers. Examples of glass fibers include E-glass fibers, S-glass fibers, A-glass fibers, C-glass fibers, D-glass fibers, ECR-glass fibers, and AR-glass fibers, with E-glass fibers, which are general-purpose glass fibers, being preferred. Basalt fibers are also called basalt fibers because they are obtained by melting and spinning basalt. Basalt fibers are known to have higher heat resistance and strength than glass fibers.

[0020] The fiber substrate 6 (glass fiber substrate or basalt fiber substrate) may be in the form of a plain weave, satin weave, nonwoven fabric, mat, knitted fabric, braided fabric, or a combination of these, or a combination of these with chopped fabric. From the viewpoint of high loading of reinforcing fibers into the reinforcing layer 5, a nonwoven fabric or mat is preferred, and a mat is more preferred. Examples of mat types include chopped strand mats in which glass fiber strands or basalt fiber strands cut to a predetermined length are randomly dispersed and layered to a uniform thickness and formed into a mat with a binder; stitch mats in which glass fiber strands or basalt fiber strands cut to a predetermined length are sewn together with another continuous fiber to form a sheet; and continuous strand mats in which continuous fibers are stacked, for example, in a spiral shape and formed into a mat with a binder. The preferred basis weight (mass per unit area) of one nonwoven fabric or mat is 30 to 600 g / m from the viewpoint of achieving both the impregnation of the geopolymer, the handleability of the mat itself, and the handleability of the polymer-containing fiber substrate (polymer-containing glass fiber substrate or polymer-containing basalt fiber substrate) impregnated with the geopolymer composition described below. 2 The count of the glass fiber strands constituting the glass fiber substrate is preferably 5 to 500 tex, and the fiber length is preferably 1 to 100 mm, more preferably 20 to 100 mm. The count of the basalt fiber strands constituting the basalt fiber substrate is preferably 5 to 500 tex, and the fiber length is preferably 1 to 100 mm, more preferably 20 to 100 mm. When the fiber substrate 6 is in a mat shape and further contains a binder that binds the reinforcing fibers together, the content of the binder in the fiber substrate is preferably 7% by mass or less, more preferably 5% by mass or less, from the viewpoint of non-combustibility, and is preferably 1% by mass or more, more preferably 3% by mass or more, from the viewpoint of workability during molding (preventing the fibers from coming off the mat).

[0021] The number of layers of the fiber substrate (glass fiber substrate or basalt fiber substrate) 6 in the reinforcing layer 5 may be appropriately selected depending on the application of the fiber-reinforced inorganic molded product 1, and is, for example, 1 to 10 layers, preferably 3 to 5 layers. The fiber substrate (glass fiber substrate or basalt fiber substrate) 6 may also be formed by cutting roving into strands of 1 to 100 mm, preferably 20 to 100 mm, and then spraying the resulting strands onto the substrate using a spray gun. From the viewpoint of improving strength, the content of the glass fiber substrate in the reinforcing layer 5 is preferably 5 to 25 mass % of the total mass of the reinforcing layer, more preferably 5 to 20 mass %. From the viewpoint of improving strength, the content of the basalt fiber substrate in the reinforcing layer 5 is also preferably 5 to 25 mass % of the total mass of the reinforcing layer, more preferably 5 to 20 mass %.

[0022] The reinforcing layer 5 may contain an inorganic filler (not shown) as needed, for example, to adjust the weight. Examples of inorganic fillers include talc, finely powdered wollastonite, silica powder, zeolite, calcium carbonate, aluminum hydroxide, barium sulfate, and crushed rocks. The particle size of the inorganic filler is not particularly limited as long as it does not interfere with the impregnation of the geopolymer composition into the geopolymer fiber substrate (glass fiber substrate or basalt fiber substrate) 6, and is preferably 5 μm or more and less than 50 μm. The content of the inorganic filler in the reinforcing layer 5 is preferably 50 mass% or less of the total mass of the reinforcing layer, from the viewpoint of both improving strength and impregnating the geopolymer composition into the fiber substrate (glass fiber substrate or basalt fiber substrate) 6.

[0023] The preferred thickness of the reinforcing layer 5 varies depending on the use of the fiber-reinforced inorganic molded body 1, but is preferably 2.0 to 10 mm, more preferably 3.0 to 6.0 mm, from the viewpoint of improving the strength of the fiber-reinforced inorganic molded body.

[0024] The preferred thickness of the fiber-reinforced inorganic molded body 1 varies depending on the application of the fiber-reinforced inorganic molded body 1, but is preferably 2.3 to 12 mm, more preferably 3.5 to 7.0 mm, from the viewpoint of improving the strength of the fiber-reinforced inorganic molded body.

[0025] [Surface layer] The fiber-reinforced inorganic molded body 1 of the present disclosure shown in FIG. 2 further includes a surface layer 2 in addition to the reinforcing layer 5. The matrix resin of the surface layer 2 is also geopolymer 3. The surface layer 2 does not include a fiber substrate 6. In this fiber-reinforced inorganic molded body 1, the surface layer 2 is provided on a reinforcing layer 5 containing glass fiber or basalt fiber. Therefore, even if the reinforcing layer 5 is highly filled with glass fiber or basalt fiber, fiber marks are prevented from appearing on the surface of the fiber-reinforced inorganic molded body 1. The fiber-reinforced inorganic molded body 1 of the embodiment shown in FIG. 2 further includes the surface layer 2, which achieves both good appearance and high strength. However, the surface layer 2 is not an essential component of the fiber-reinforced inorganic molded body 1 of the present disclosure and may be present or absent. The term "surface of the fiber-reinforced inorganic molded body" refers to the front surface of the fiber-reinforced inorganic molded body, i.e., the surface that comes into contact with the inner surface of the mold during molding within the mold.

[0026] The surface layer 2 may contain reinforcing fibers (not shown) dispersed in the geopolymer 3, as needed, to reinforce the surface layer 2. Any reinforcing fibers can be used depending on the application of the fiber-reinforced inorganic molded body 1. From the viewpoints of good appearance of the surface of the fiber-reinforced inorganic molded body 1 and high reproducibility of a design when forming a design on the surface of the fiber-reinforced inorganic molded body 1, for example, reinforcing fibers such as vinylon, acrylic, PE, PP, cellulose, aramid, carbon fiber, alumina fiber, and glass fiber can be preferably used as the reinforcing fibers.

[0027] The active filler used to generate the geopolymer 3 constituting the surface layer 2 is preferably the metakaolin described above, which is used to generate the geopolymer contained in the reinforcing layer 5. In this case, at least one type of reinforcing fiber selected from ordinary glass fiber (excluding alkali-resistant fiber) and basalt fiber may be included, as long as it does not affect the surface properties of the fiber-reinforced inorganic molded body 1. The content of these reinforcing fibers in the surface layer 2 is preferably 0.3 to 1.0 mass% of the total mass of the surface layer 2, from the viewpoints of improving strength, improving the appearance of the surface of the fiber-reinforced inorganic molded body 1, and ensuring high reproducibility of designs when forming designs on the surface of the fiber-reinforced inorganic molded body 1. From the viewpoints of improving strength and dispersibility of the reinforcing fibers, the fiber diameter of the reinforcing fibers is preferably 10 to 50 μm, and the fiber length is preferably 1 to 10 mm.

[0028] The surface layer 2 may contain, as needed, an aggregate 4 that is insoluble in water and does not react with alkali metal silicates in order to reinforce the surface layer 2. In particular, when forming a design on the surface of the fiber-reinforced inorganic molded body 1, it is preferable to contain the aggregate 4 from the viewpoint of preventing a decrease in strength due to fine irregularities and the occurrence of cracks. Examples of the aggregate 4 include wollastonite, zircon sand, silica sand, crystalline alumina, mica, copper tangle, limestone, and municipal solid waste slag. These may be used alone or in combination of two or more. Among these, wollastonite is preferred because it is acicular and has the effect of preventing shrinkage.

[0029] The particle size of the aggregate 4 is preferably 50 to 1000 μm, more preferably 50 to 200 μm, from the viewpoints of good appearance and high reproducibility of the design. The content of the aggregate 4 in the surface layer 2 is preferably 10 to 50 mass % of the total mass of the surface layer 2, from the viewpoints of improving strength, good appearance of the surface of the fiber-reinforced inorganic molded body 1, and high reproducibility of the design. In this application, the term "particle size" refers to the 50% (by weight) cumulative particle size, that is, the particle size at which the particle size reaches 50% by weight of the total aggregate when accumulating from smallest particle sizes.

[0030] The preferred thickness of the surface layer 2 varies depending on the use of the fiber-reinforced inorganic molded body 1 and whether or not a design is formed, but from the viewpoint of the strength and good appearance of the entire molded body, it is preferably 0.3 to 2.0 mm, more preferably 0.5 to 1.0 mm.

[0031] The surface of the surface layer 2, i.e., the surface of the fiber-reinforced inorganic molded body 1, may be a smooth surface without any pattern as shown in Fig. 1, or may have a design formed thereon. Examples of designs include traditional Japanese patterns such as tortoiseshell patterns, checkered patterns, and shippo-tsunagi patterns, as well as geometric patterns, leather grain patterns, rock surfaces, wood grain, wood surfaces (bark), comb-hiki patterns, scraped-off patterns, and chipped patterns.

[0032] 1 and 2 is a flat plate-like form of the fiber-reinforced inorganic molded article of the present disclosure, but the fiber-reinforced inorganic molded article of the present disclosure is not limited to a flat plate-like form and may be a curved plate-like molded article. Furthermore, one form of the fiber-reinforced inorganic molded article of the present disclosure may be a three-dimensional object such as an artificial rock, an artificial tree, a monument, or a statue.

[0033] [Method of manufacturing fiber-reinforced inorganic molded body] Next, a method for producing a molded article according to one embodiment of the present disclosure will be described using as an example a method for producing a fiber-reinforced inorganic molded article according to the embodiment shown in FIG. In one aspect, the present disclosure relates to a method for producing a fiber-reinforced inorganic molded body, which comprises placing multiple glass fiber substrates impregnated with a geopolymer composition (hereinafter referred to as the "first geopolymer composition" to distinguish it from the second geopolymer composition described below, which is used to form the surface layer) in a mold coated with a release agent to produce a laminated structure, curing and hardening the laminated structure, and then releasing it from the mold.

[0034] The first geopolymer composition contains, for example, metakaolin as the active filler and an alkali silicate solution. The first geopolymer composition may contain an inorganic filler, etc., as needed. Details of the preferred alkali silicate solution, metakaolin, and inorganic filler are as described above. The solids concentration of the first geopolymer composition is preferably 70 to 85 mass% from the viewpoint of impregnation into a fiber substrate (glass fiber substrate or basalt fiber substrate) 6. In the first geopolymer composition, the preferred content of alkali metal silicate, calculated as solids, is preferably 40 to 60 mass parts per 100 mass parts of metakaolin. The preferred content of inorganic filler is preferably 75 mass parts or less per 100 mass parts of metakaolin from the viewpoint of the strength and processability of the fiber-reinforced inorganic molded body.

[0035] The fiber substrate 6 impregnated with the first geopolymer composition is placed in the mold by either one or both of the following methods (I) and (II). (I) After placing the fiber substrate 6 in a mold to which a release agent has been applied, the fiber substrate 6 is impregnated with the first geopolymer composition to form a polymer-containing fiber substrate (a polymer-containing glass fiber substrate or a polymer-containing basalt fiber substrate). (II) A polymer-containing fiber substrate is prepared by impregnating a fiber substrate 6 with a first geopolymer composition, and the resulting fiber substrate is placed in a mold to which a release agent has been applied. That is, the fiber substrate 6 is impregnated with the first geopolymer composition, and then the polymer-containing fiber substrate is placed in a mold to which a release agent has been applied.

[0036] In method (I), the impregnation of the fiber substrate 6 with the first geopolymer composition is carried out, for example, by hand using a brush or roller. Air is removed from the fiber substrate 6 at the same time as the impregnation. In method (II), the impregnation of the fiber substrate 6 with the first geopolymer composition is carried out, for example, by immersing the fiber substrate in the first geopolymer composition. Air is removed from the fiber substrate 6 at the same time as the immersion.

[0037] For example, the method (I) or the method (II) is carried out a predetermined number of times to form a laminated structure in which, for example, a plurality of polymer-containing fiber substrates (polymer-containing glass fiber substrates or polymer-containing basalt fiber substrates) are laminated.

[0038] Next, the laminated structure is cured, for example, after the first geopolymer composition has completely hardened, and then demolded. Through curing, the laminate of polymer-containing fiber substrates (polymer-containing glass fiber substrates or polymer-containing basalt fiber substrates) becomes the reinforcing layer 5, and the first geopolymer composition becomes the matrix resin of the reinforcing layer 5. The curing temperature is preferably 10 to 90°C, more preferably 20 to 60°C, and the relative humidity is preferably 50 to 90%. The curing time is preferably 2 to 96 hours, more preferably 2 to 24 hours.

[0039] The molding die used in the method for producing a fiber-reinforced inorganic molded article according to one embodiment of the present disclosure may be made of, for example, urethane rubber, fiber-reinforced plastic, silicone rubber, etc. If necessary, a mold release agent may be used, such as a wax-based, silicone-based, fluorine-based, or surfactant-based mold release agent.

[0040] In the method for manufacturing a fiber-reinforced inorganic molded body including a surface layer shown in Figure 2, a second geopolymer composition is applied to a mold, and multiple fiber substrates impregnated with the first geopolymer composition are placed on top of the second geopolymer composition applied to the mold to create a laminated structure.The laminated structure is then cured, for example, to completely harden the second geopolymer composition, and then the structure is demolded to obtain a fiber-reinforced inorganic molded body.

[0041] The second geopolymer composition contains, for example, metakaolin as an active filler and an alkali silicate solution. The second geopolymer composition may contain, as needed, reinforcing fibers (reinforcing fibers) such as organic fibers, aggregates, and the like. Suitable alkali silicate solutions, metakaolin, reinforcing fibers, and aggregates are as described above. The solids concentration of the second geopolymer composition is preferably 70 to 85% by mass from the viewpoint of application. In the second geopolymer composition, the preferred content of alkali metal silicate is 35 to 60 parts by mass per 100 parts by mass of metakaolin, calculated as solids. The preferred content of aggregate 4 is 20 to 100 parts by mass per 100 parts by mass of metakaolin from the viewpoints of shrinkage prevention and molded body strength.

[0042] The fiber-reinforced inorganic molding including the surface layer 2 shown in Figure 2 can be produced by the method described in JP 2022-174741 A, except that the first geopolymer composition and the second geopolymer composition of the present disclosure are used. [Example]

[0043] The present invention will be specifically described below using examples, but the present invention is not limited to the following examples.

[0044] <Raw materials used> (1) Geopolymer composition The following active filler and potassium silicate aqueous solution were mixed in a mass ratio of 100:100 (100:45.4 in terms of solid content) to prepare a geopolymer mortar (geopolymer composition). Geopolymer composition A Metakaolin (manufactured by Sovuekreh, electrical conductivity difference 1.78 mS / cm, average particle size 3.1 μm) Potassium silicate aqueous solution (Osaka Silica Co., Ltd., 1.4 50° (molar ratio 1.4, solid content 45.4% by mass) Geopolymer composition B Metakaolin (manufactured by Sobuekree, electrical conductivity difference 2.04 mS / cm, average particle size 2.9 μm) Potassium silicate aqueous solution (Osaka Keiso Co., Ltd., molar ratio 1.4, solid content 45.4% by mass) Geopolymer composition C Metakaolin (manufactured by Sobuekree, electrical conductivity difference 1.44 mS / cm, average particle size 3.0 μm) Potassium silicate aqueous solution (Osaka Silica Co., Ltd., 1.4 50° (molar ratio 1.4, solid content 45.4% by mass) Geopolymer composition D Fly ash (JISA6201 fly ash type II, electrical conductivity difference 0.36mS / cm) Potassium silicate aqueous solution (Osaka Silica Co., Ltd., 1.4 50° (molar ratio 1.4, solid content 45.4% by mass) (2) Fiber base material Basalt mat (Each Dream, mass per unit area: 450g / m 2 ) E-glass chopped strand mat (manufactured by Nittobo Co., Ltd., mass per unit area: 450 g / m 2 )

[0045] Example 1 A wax-based mold release agent was applied to a urethane rubber mold without a pattern. Then, a basalt mat (manufactured by Each Dream Co., Ltd., mass per unit area: 450 g / m) was applied to the urethane rubber mold. 2 ) was placed on the mat, and the geopolymer composition A was applied by rubbing it into the mat, and the mat was impregnated while removing the air from the mat to form a polymer-containing glass fiber substrate. This was repeated four times. The resulting laminated structure was cured for 50 hours at a temperature of 20 ° C and a relative humidity of 60% until it hardened to a level where it could not be deformed. Then, it was demolded to obtain the fiber-reinforced inorganic molded body of Example 1. After 20 hours of curing, the laminated structure was semi-hardened and could be easily demolded. The semi-hardened body was hard enough to be bent by hand. The laminated structure was completely hardened after 100 hours. The thickness of the fiber-reinforced inorganic molded body (reinforced layer) in Example 1 was 4.0 mm, and the content of the mat in the fiber-reinforced inorganic molded body was 17 mass % of the total mass.

[0046] Example 2 A fiber-reinforced inorganic molded body of Example 2 was obtained in the same manner as in Example 1, except that geopolymer composition B was used instead of geopolymer composition A. After 20 hours of curing, the laminated structure was semi-cured and could be easily demolded. The semi-cured body was hard enough to be bent by hand. The laminated structure was completely cured after 50 hours. The thickness of the fiber-reinforced inorganic molded body (reinforced layer) of Example 2 was 4.0 mm, and the content of the mat in the fiber-reinforced inorganic molded body was 17 mass % of the total mass.

[0047] (Comparative Example 1) A fiber-reinforced inorganic molded body of Comparative Example 1 was obtained in the same manner as in Example 1, except that geopolymer composition C was used instead of geopolymer composition A. After 90 hours of curing, the laminated structure was semi-cured and could be easily demolded. The semi-cured body was hard enough to be bent by hand. The laminated structure was completely cured after 100 hours. The thickness of the fiber-reinforced inorganic molded body (reinforced layer) of Comparative Example 1 was 4.0 mm, and the content of the mat in the fiber-reinforced inorganic molded body was 17 mass % of the total mass.

[0048] (Comparative Example 2) A fiber-reinforced inorganic molded body of Comparative Example 2 was obtained in the same manner as in Example 1, except that geopolymer composition D was used instead of geopolymer composition A.

[0049] <Alkali degradation test of reinforcing fibers> Aqueous potassium hydroxide solutions having a pH of 12.5, 12.0, or 11.5 at 25° C. were prepared by diluting the aqueous potassium hydroxide solution with water. Also, a hardening liquid (aqueous potassium silicate solution) with a pH of 14 was prepared. Next, the prepared potassium hydroxide aqueous solution of various pH levels or the hardening solution was placed in a sealed container, and basalt mat (manufactured by Each Dream Co., Ltd., mass per unit area: 450 g / m) was added to the aqueous solution. 2It was immersed in ([0]) and the container was sealed. In this state, the sealed container was placed in a thermostat at 80°C, and after placing it in the thermostat, the state of the mat after 7 days, 14 days, 21 days, and 28 days was observed under a microscope. Even when the basalt mat was immersed in an aqueous potassium hydroxide solution at pH 12.5 for 28 hours, no deterioration of the fibers was observed. When the basalt mat was immersed in a curing solution with a pH of 14, the basalt fibers melted almost completely after 7 days.

[0050] <pH Change Measurement> The semi-cured bodies of Example 1, Example 2, and Comparative Example 1 were each placed in a beaker, crushed, and separated into reinforcing fibers and a geopolimer material. The geopolimer material was mixed with the same amount of water, and the pH (25°C) of the mixture was measured. The results are shown in FIG. 3 below. The cured bodies of Example 1, Example 3, and Comparative Example 1 with different curing times were each crushed and separated into reinforcing fibers and a geopolimer material. The geopolimer material was mixed with the same amount of water, and the pH (25°C) of the mixture was measured. The results are shown in FIG. 3 below.

[0051] As shown in FIG. 3, in Example 1 and Example 2, the pH decreased relatively early from the start of curing and became a semi-cured body within 20 hours, and thereafter the pH was stably maintained at a low value (pH = 9 - 10). On the other hand, in Comparative Example 1, it took about 90 hours until the pH dropped below 12, and the subsequent pH was also about 11 - 12, showing a trend of higher values than in Example 1. In particular, for Example 2 using metakaolin with an electrical conductivity difference of 2.04 mS / cm, it was confirmed that the pH dropped rapidly from the start of curing.

[0052] <Flexural Strength Measurement> Water was injected into a plastic sealed container, and the fiber-reinforced inorganic molded body of Example 1 was immersed in the water. Then, the container containing these was covered with a lid and sealed, and this was placed in a thermostat at 80 °C for a predetermined time, then taken out, and then placed in a thermostat at 60 °C to be dried. Next, according to the three-point bending test of JIS A 1408, the bending strength was measured. The bending strength was measured three times for separate samples. The said predetermined time was 7 days, 14 days, 21 days, and 28 days after the fiber-reinforced inorganic molded body was placed in the thermostat. The measurement results of the bending strength are shown in FIG. 4. Also, FIG. 4 shows the pH of water (20 °C) 7 days, 14 days, 21 days, and 28 days after the fiber-reinforced inorganic molded body was placed in the thermostat.

[0053] As shown in FIG. 4, the bending strength of the fiber-reinforced inorganic molded body of Example 1 did not decrease with the passage of time, and the pH of the water in which the fiber-reinforced inorganic molded body was immersed was also kept almost constant.

[0054] From the results shown in Table 3 and Table 4, it was confirmed that in Examples 1 and 2, the deterioration of basalt fibers due to alkali was suppressed more than in Comparative Example 1.

[0055] A fiber-reinforced inorganic molded body using an E-glass chopped strand mat (manufactured by Nitto Boseki Co., Ltd., mass per unit area: 450 g / m 2 ) was produced, and the above <alkali deterioration test of reinforcing fiber>, <pH change measurement>, and <bending strength measurement> were carried out. As a result similar to Example 1 was obtained, and it was confirmed that the deterioration of E-glass fiber due to alkali was suppressed.

[0056] The fiber-reinforced inorganic molded body of Comparative Example 2, which used fly ash as an active filler, was immersed in water. The container containing the fiber-reinforced inorganic molded body was then sealed with a lid and placed in an incubator at 80°C. Figure 5 shows the pH of the water 7, 14, 21, and 28 days after the fiber-reinforced inorganic molded body of Comparative Example 2 was placed in the incubator. For comparison, Figure 5 also shows the pH of the water for the fiber-reinforced inorganic molded body of Example 1. As shown in Figure 5, the pH (80°C) of the water for Example 1 was lower than that for Comparative Example 2, being 10 or less. This indicates that the use of metakaolin, which has an electrical conductivity difference of 1.5 mS / cm to 2.1 mS / cm, as the active filler, is more effective in suppressing alkali-induced deterioration of reinforcing fibers such as glass fiber and basalt fiber than the use of fly ash. [Industrial Applicability]

[0057] Suitable uses of the molded article of the present disclosure include, for example, artificial rocks, artificial trees, monuments, statues, and flat, wavy, or dome-shaped building materials, panels, and the like, which are installed indoors or outdoors. [Explanation of symbols]

[0058] 1 Fiber-reinforced inorganic molding 2 Surface layer 3 Hardened geopolymer 4 Aggregate 5 reinforcement layer 6. Fiber substrate

Claims

1. A fiber-reinforced inorganic molded body including a reinforcing layer, The reinforcing layer includes a fiber substrate containing reinforcing fibers and a geopolymer as a matrix resin, The active filler contained in the raw material of the geopolymer is metakaolin having an electrical conductivity difference of 1.5 mS / cm or more and 2.1 mS / cm or less, A fiber-reinforced inorganic molded product, wherein the reinforcing fibers are at least one type of fiber selected from glass fibers (excluding alkali-resistant fibers) and basalt fibers.

2. The fiber-reinforced inorganic molded body according to claim 1, wherein the metakaolin has an average particle size of 1 μm or more and 20 μm or less.

3. 2. The fiber-reinforced inorganic molded product according to claim 1, wherein the glass fibers are E-glass fibers.

4. The fiber-reinforced inorganic molded article according to claim 1 , wherein the fiber substrate is in a mat shape.

5. The fiber-reinforced inorganic molded body according to claim 1, wherein one surface layer of the fiber-reinforced inorganic molded body does not contain the reinforcing fiber or has a lower content of the reinforcing fiber than the reinforcing layer and contains the geopolymer.

6. A method for producing a fiber-reinforced inorganic molded body according to any one of claims 1 to 5, The method includes placing a plurality of sheets of the fiber substrate impregnated with the geopolymer composition in a mold, curing the sheets to harden them, and then demolding them. The geopolymer composition comprises an alkaline silicate solution and the metakaolin having an electrical conductivity difference of 1.5 mS / cm or more and 2.1 mS / cm or less. A method for producing a fiber-reinforced inorganic molded body.

7. A plurality of polymer-containing fiber substrates in which the geopolymer composition is impregnated into the fiber substrate are prepared, and they are stacked in the molding die to produce a laminated structure. The method for producing a fiber-reinforced inorganic molded body according to claim 6, wherein the laminated structure is cured and hardened, and then demolded.

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