Geopolymer-producing composition, geopolymer cured body, and thermal insulating material

Abstract

To provide: a geopolymer-producing composition which enables the production of a geopolymer cured body having enhanced thermal insulating properties; a geopolymer cured body having enhanced thermal insulating properties; and a thermal insulating material including the geopolymer cured body and having enhanced thermal insulating properties.SOLUTION: The geopolymer-producing composition comprises: an aluminosilicate; inorganic particles; an activator; and water, where the inorganic particles are hollow particles. The geopolymer cured body comprises a geopolymer and inorganic particles, where the inorganic particles are hollow particles. The thermal insulating material includes the geopolymer cured body.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for producing a geopolimer, a cured geopolimer, and a heat insulating material.

Background Art

[0002] Generally, as a heat insulating material used for electronic components, moving bodies (such as vehicles and aircraft), etc., for example, a heat insulating material made of a polyurethane-based foam (Patent Document 1) is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, miniaturization and high functionality of electronic components, and multifunctionalization of moving bodies such as vehicles and aircraft have been promoted. In response to this, in particular, the demand for heat insulating sheets formed in a thin sheet shape has been increasing. Even when formed in a sheet shape, a heat insulating material having more excellent heat insulating properties is required.

[0005] However, the conventional heat insulating materials such as Patent Document 1 did not have sufficient heat insulating properties to cope with the above-described changes. The problem to be solved by the present invention is to provide a material having more excellent heat insulating properties.

Means for Solving the Problems

[0006] The present inventor has conducted intensive research, obtained the finding that a novel cured geopolimer is useful as a material for a heat insulating material, and found that the above problems can be solved, thereby completing the present invention. That is, the present invention is as follows.

[0007] One aspect of the present invention is a composition for producing a geopolimer. The composition for producing a geopolimer includes an aluminosilicate, inorganic particles, an activator, and water, wherein the inorganic particles are hollow particles.

[0008] Another aspect of the present invention is a cured geopolimer. The cured geopolimer includes a geopolimer and inorganic particles, wherein the inorganic particles are hollow particles.

[0009] In the cured geopolimer of the above aspect, it is preferably in the form of a sheet.

[0010] Another aspect of the present invention is a heat insulating material. The heat insulating material includes the cured geopolimer of any of the above aspects.

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a composition for producing a geopolimer capable of obtaining a cured geopolimer having more excellent heat insulating properties; a cured geopolimer having more excellent heat insulating properties; and a heat insulating material including the cured geopolimer and having more excellent heat insulating properties.

Embodiments for Carrying Out the Invention

[0012] In this specification, the notation "a~b" in the description of a numerical range represents a to b inclusive, unless otherwise specified.

[0013] In this specification, when a plurality of upper limit values and a plurality of lower limit values are separately described, all numerical ranges that can be freely combined and set from these upper limit values and lower limit values are considered to be described in this specification.

[0014] In this specification, "powder particles" refers to an aggregate of "powder" or "particles".

[0015] The average particle diameter (median particle diameter D50 (volume basis)) of the powder or particles can be measured by a laser diffraction particle size distribution analyzer.

[0016] Unless otherwise specified, various measurements are carried out at an environmental temperature of room temperature (25 °C).

[0017] 1. Composition for producing geopolymers The composition for producing geopolymers according to this embodiment contains aluminosilicate, inorganic particles, an activator, and water. By curing the composition for producing geopolymers, a geopolymer cured body described later can be obtained. That is, the composition for producing geopolymers is a precursor of the geopolymer cured body.

[0018] A geopolymer refers to an amorphous polymer (polymer) made of materials mainly composed of aluminum, silicon, etc., and is obtained by the reaction of aluminosilicate and an activator described later.

[0019] 1-1. Aluminosilicate Aluminosilicate (xM2O·yAl2O3·zSiO2·nH2O, M is an alkali metal) is a compound having a structure in which part of the silicon atoms in the silicate are replaced by aluminum atoms.

[0020] Examples of aluminosilicates include natural aluminosilicate minerals such as illite, phillipsite, kaolinite, pyrophyllite, andalusite, bentonite, kyanite, millisite, globenite, amesite, cordierite, feldspar, and allophane; calcined natural aluminosilicate minerals such as imogolite and metakaolin; fly ash obtained from the combustion of coal; blast furnace slag obtained when converting iron ore into cast iron in a blast furnace; etc. One or more mixtures selected therefrom may be mentioned. Among them, calcined natural aluminosilicate minerals are preferred, and metakaolin is particularly more preferred.

[0021] Commercially available products of these substances can be used, and one or more of them can be used in combination. Further, the aluminosilicate is used in the form of powder or granules, and can be adjusted to an aluminosilicate having a desired particle size by appropriately pulverizing and classifying to use a specific fraction.

[0022] Meta-kaolin, which is particularly preferable as the aluminosilicate, is a compound represented by the chemical formula Al2O3·2SiO2. The content of meta-kaolin relative to the total mass of the aluminosilicate is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. When the content of meta-kaolin relative to the total mass of the aluminosilicate is within the above range, a diopolymer cured body excellent in strength can be stably obtained.

[0023] The powder particles of the aluminosilicate preferably have an average particle diameter of 0.1 to 50 μm, more preferably 0.3 to 30 μm, and still more preferably 0.5 to 10 μm. When the average particle diameter of the powder particles is within this range, the heat insulation property of the produced diopolymer cured body can be further improved.

[0024] The content of the aluminosilicate is preferably 5% by mass or more, 10% by mass or more, 20% by mass or more, etc., and preferably 80% by mass or less, 70% by mass or less, 60% by mass or less, etc., based on the total mass of the composition for producing the diopolymer. By setting the content of the aluminosilicate within the above range, it is easy to increase the strength of the diopolymer cured body.

[0025] 1-2. Inorganic Particles The inorganic particles (inorganic fillers) are inorganic particles other than the above-mentioned aluminosilicate, and examples thereof include oxides such as aluminum oxide, silicon dioxide (silica), spinel, zirconium oxide, magnesium oxide, titanium oxide, and cerium oxide; hydroxides such as aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; carbides such as silicon carbide and boron carbide; nitrides such as silicon nitride and boron nitride; carbonates such as nickel carbonate, calcium carbonate, and magnesium carbonate; sulfates such as calcium sulfate; and the like. One kind selected from the above-mentioned inorganic particles, or a mixture of two or more kinds may be used.

[0026] The inorganic particles of the present embodiment preferably contain silicon dioxide (silica) in particular. With respect to the total mass of the inorganic particles, the content of silicon dioxide (silica) is preferably 60% by mass or more, 70% by mass or more, 75% by mass or more, etc., and preferably 99% by mass or less, 95% by mass or less, 90% by mass or less, etc. Silica is mainly divided into wet silica synthesized in a liquid and dry silica synthesized by hydrolysis at a high temperature. In the present embodiment, either wet silica or dry silica may be used as the inorganic particles. By containing silica as the inorganic particles, the strength of the geopolimer cured body can be improved.

[0027] The inorganic particles of the present embodiment are spherical hollow particles. Hollow particles are particles having a structure with a cavity surrounded by an outer shell inside. The internal cavity may be sealed, or a part of it may communicate with the outside. By making the inorganic particles spherical, the fluidity of the composition for producing geopolimer after blending can be increased. Also, by making the inorganic particles hollow particles, air is more easily retained inside the geopolimer cured body, so the heat insulation of the geopolimer cured body can be further improved. Furthermore, the weight of the geopolimer cured body can be reduced compared to when the inorganic particles are solid.

[0028] The floating rate of the inorganic particles is preferably 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, etc. By setting the floating rate of the inorganic particles within the above range, the weight of the geopolimer cured body can be further reduced. The method for measuring the floating rate is as follows.

[0029] (Method for Measuring the Floating Rate) Water is put into a 1000 ml beaker containing 15 g of a sample (inorganic particles), stirred well, and then left to stand until the water becomes clear. The floating sample is collected and dried. Then, the weight (W) of the dried product is measured, and the floating rate is calculated from the formula W / 15×100.

[0030] In this embodiment, the average particle diameter of the inorganic particles is preferably in the range of 0.1 to 100 μm, more preferably in the range of 1 to 90 μm, and even more preferably in the range of 5 to 80 μm. The bulk density of the inorganic particles is preferably in the range of 0.01 to 1.00 g / cm 3 and more preferably in the range of 0.05 to 0.80 g / cm 3 and even more preferably in the range of 0.10 to 0.50 g / cm 3 . The method for measuring the bulk density is as follows.

[0031] (Method for measuring bulk density) The bulk density is measured based on JIS R1628-1997 (Method for measuring bulk density of fine ceramic powder).

[0032] The true specific gravity of the inorganic particles is preferably in the range of 0.01 to 1.50 g / cm 3 and more preferably in the range of 0.05 to 1.00 g / cm 3 . The method for measuring the true specific gravity is as follows.

[0033] (Method for measuring true specific gravity) The true specific gravity can be measured, for example, using a pycnometer automatic powder and granule true specific gravity measuring instrument.

[0034] The content of the inorganic particles is not particularly limited, and is preferably 5% by mass or more, 10% by mass or more, 25% by mass or more, 30% by mass or more, etc., and preferably 50% by mass or less, 45% by mass or less, 40% by mass or less, etc., based on the total mass of the composition for producing the geopolymers. When the content of the inorganic particles is within the above range, the heat insulation property of the geopolymers cured body can be further improved.

[0035] 1-3. Activator The activator in the embodiment acts as a crosslinking agent when curing the composition for producing a geopolimer. The activator in this embodiment is not particularly limited, and an alkali activator, an acidic activator, or the like can be used. Examples of the alkali activator include substances containing alkali metal compounds such as sodium hydroxide and potassium hydroxide. Examples of the acidic activator include phosphoric acid-based activators, nitric acid-based activators, sulfuric acid-based activators, and the like. In this embodiment, among these activators, an acidic activator is preferred, and particularly, a phosphoric acid-based activator is more preferred. Hereinafter, the case of using a phosphoric acid-based activator as an example of the activator will be described.

[0036] In addition, even when an acidic activator other than the phosphoric acid-based activator, an alkali activator, or the like is used as the activator, the description of their content (addition amount), concentration, etc. can be appropriately adjusted with reference to the case of using the phosphoric acid-based activator described below so that crosslinking by the activator proceeds sufficiently. For example, the content of the activator with respect to the total mass of the composition for producing a geopolimer is preferably 1% by mass or more, 5% by mass or more, 8% by mass or more, etc., and preferably 60% by mass or less, 55% by mass or less, 50% by mass or less, etc.

[0037] The phosphoric acid-based activator used as the activator in this embodiment is not particularly limited. Examples of the phosphoric acid-based activator include mixtures such as aqueous solutions containing phosphoric acid (H3PO4), salts (phosphates) formed from phosphate ions (PO4 3- ), etc. The phosphate may be a salt that reacts with water to release phosphate ions (PO4 3- ), etc. For example, ammonium dihydrogen phosphate (NH4H2PO4), sodium dihydrogen phosphate (NaH2PO4), potassium dihydrogen phosphate (KH2PO4), ammonium hydrogen phosphate ((NH4)2HPO4), sodium hydrogen phosphate (Na2HPO4), etc. can be mentioned.

[0038] As a suitable example of the phosphoric acid-based activator, a high-concentration phosphoric acid aqueous solution can be mentioned. The phosphoric acid concentration of the high-concentration phosphoric acid aqueous solution is preferably 45% by mass or more, 50% by mass or more, 55% by mass or more, etc., and preferably 95% by mass or less, 90% by mass or less, 85% by mass or less, etc. By using the high-concentration phosphoric acid aqueous solution with the above phosphoric acid concentration, crosslinking and kneading can be efficiently performed.

[0039] When preparing the composition for producing a diopolymer, the ratio of the addition amount of the high-concentration phosphoric acid aqueous solution to the total mass of the composition for producing a diopolymer is preferably 1% by mass or more, 5% by mass or more, 8% by mass or more, etc., and preferably 60% by mass or less, 55% by mass or less, 50% by mass or less, etc.

[0040] The phosphoric acid concentration relative to the total mass of the composition for producing a diopolymer is preferably, for example, 0.4 to 57.0% by mass, more preferably 4.0 to 29.0% by mass, and even more preferably 7.0 to 22.0% by mass.

[0041] If the phosphoric acid concentration relative to the total mass of the composition for producing a diopolymer is within the above-mentioned range, either a high-concentration phosphoric acid aqueous solution or a phosphate can be used as the activator. Also, the order of mixing each component when preparing the composition for producing a diopolymer is not particularly limited.

[0042] Specifically, when using a high-concentration phosphoric acid aqueous solution as the activator, the composition for producing a diopolymer may be prepared by adding it to a mixture of the solid component and water (described later) while stirring. Also, when using a phosphate as the activator, the composition for producing a diopolymer may be prepared by adding water (described later) to a mixture of the phosphate and the solid component.

[0043] 1-4. Water The water in this embodiment includes deionized water, distilled water, or water containing up to 0.1% by mass of impurities, for example, ordinary tap water.

[0044] The water content is not particularly limited as long as the phosphoric acid concentration relative to the total mass of the composition for producing the geopolymers is within the above-described range, and a range of 5 to 50% by mass is preferable relative to the total mass of the composition for producing the geopolymers.

[0045] 1-5. Other Components The composition for producing the geopolymers may contain other components as long as the effects of the present invention are not impaired. Examples of the other components include pH adjusters, fluidizing agents, shrinkage reducing agents, rust preventives, waterproofing materials, setting retarders, defoaming agents, dust reducing agents, pigments, and the like. Further, it may contain glass fibers or the like as a reinforcing material.

[0046] The content of the other components is not particularly limited, and a range of 1 to 10% by mass is preferable relative to the total mass of the composition for producing the geopolymers.

[0047] 2. Geopolymer Hardened Body The geopolymer hardened body of the present embodiment can be produced by mixing (kneading) each component of the above-described composition for producing the geopolymers and drying and hardening them. That is, the geopolymer hardened body contains a geopolymer and inorganic particles.

[0048] The conditions for mixing each component of the composition for producing the geopolymers are not particularly limited as long as a geopolymer hardened body can be obtained. The mixing method may be kneading using a mortar mixer, a concrete mixer, or the like. After kneading, it is preferable to cure at room temperature or while heating. The curing time varies depending on the temperature, and the lower the temperature, the longer the curing time required. For example, the curing time is preferably 7 days or more at room temperature and 3 to 4 days at 60°C.

[0049] The geopolymer hardened body of the present embodiment is preferably in the form of a sheet. The heat insulating material provided with the sheet-like geopolymer hardened body can be used for various applications (electronic components, moving bodies, etc.) described later.

[0050] The geopolymer cured body of the present embodiment preferably has a compressive strength measured by a compression test (see the examples described later in detail) of more than 0.2 MPa, 2 MPa or more, 5 MPa or more, 10 MPa or more, 20 MPa or more, 30 MPa or more, 40 MPa or more, 50 MPa or more, etc. If the compressive strength is within the above range, sufficient strength can be obtained even when the geopolymer cured body is formed into a sheet shape.

[0051] The geopolymer cured body of the present embodiment has an apparent density (see the examples described later in detail) of 100 kg / m 3 or more, 200 kg / m 3 or more, 300 kg / m 3 or more, etc., preferably 1060 kg / m 3 or less, 800 kg / m 3 or less, 600 kg / m 3 or less, 100 kg / m 3 or less, etc. If the apparent density is within the above range, the geopolymer cured body can be lightened. In addition, since air can be easily taken into the geopolymer cured body, the heat insulation property can be further improved.

[0052] The geopolymer cured body of the present embodiment preferably has a surface temperature measured by a heat insulation test (see the examples described later in detail) of 360 °C or less, 330 °C or less, 310 °C or less, etc. The heat insulation property of the geopolymer cured body of the present embodiment can be evaluated by the heat insulation test.

[0053] 3. Applications of the heat insulating material The heat insulating material of the present embodiment preferably includes the above-described geopolymer cured body. Since the heat insulating material of the present embodiment has excellent heat insulating properties even when formed into a sheet shape, it can be suitably used as a heat insulating material for electronic components, a heat insulating material for heat storage devices used in various applications including houses, vehicles, and industrial uses, a heat insulating material used in an engine room of an automobile, a heat insulating material used to keep the passenger compartment of an automobile warm, a heat insulating material covering a fuel cell of an automobile, etc.

Examples

[0054] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the following embodiments. as follows.

[0055] ≪Examples and Comparative Examples≫ <Preparation of Composition for Producing Geopolymer> Each component of the composition for producing geopolymer was prepared as follows. · Inorganic particles A to D shown in Tables 1 and 2 below · Metakaolin as an aluminosilicate {NN kaolin clay, manufactured by Takehara Chemical Industry Co., Ltd., heated at 800 °C for 10 hours to be amorphized} · Concentrated phosphoric acid aqueous solution (85%) as an activator, manufactured by Kanto Chemical Co., Inc. · Distilled water · Glass fiber as a reinforcing material {chopped strand, CS6J - 888, manufactured by Nitto Boseki Co., Ltd.}

[0056]

Table 1

[0057]

Table 2

[0058] The above-mentioned solid components were mixed in the amounts shown in Table 3 below. While stirring the obtained mixture under the following stirring conditions, it was added to the concentrated phosphoric acid aqueous solution to prepare a composition for producing geopolymer. (Stirring conditions) Mixer (Three - one motor BL600, manufactured by Shinto Kagaku Co., Ltd.) Rotation speed: 790 rpm Stirring time: 20 minutes

[0059] <Production of Geopolymer Hardened Body> The composition for producing the obtained geopolymers was cured under the following conditions. Specifically, the composition for producing geopolymers was poured into a silicone mold, pressed with a 3-mm spacer while heating, and molded. After demolding, curing was performed in a thermo-hygrostat to produce geopolymer cured bodies of each of the following Examples and Comparative Examples. (Heating conditions) Temperature: 120 °C Time: 15 minutes (Curing conditions) Temperature: 23 °C Humidity: 55% Time: 24 hours

[0060] For the geopolymer cured bodies of each of the Examples and Comparative Examples, a heat insulation test, a compression test, and measurement of the apparent density (kg / m 3 ) were carried out. The evaluation results are shown in Table 3 below.

[0061] (Heat insulation test) Test samples (thickness 3 mm, 100 φ) of the geopolymer cured bodies of each of the Examples and Comparative Examples were heated on a hot plate (C-MAG HP4, manufactured by IKA) at 500 °C for 5 minutes, and then the surface temperature at the center of each test sample was measured from a height of 200 mm using a thermal image radiation thermometer (FLIR TG167, manufactured by FLIR).

[0062] (Evaluation criteria for heat insulation) A: Surface temperature is 330 °C or lower B: Surface temperature exceeds 330 °C and is less than 360 °C C: Surface temperature is 360 °C or higher

[0063] (Compression test) Test samples (thickness 3 mm, 10 φ) of the geopolymer cured bodies of each of the Examples and Comparative Examples were subjected to full-surface compression at a compression rate of 1 mm / min using an autograph (AG-X 10 kN, manufactured by Shimadzu Corporation), and the compression strength until material failure was measured.

[0064] (Evaluation criteria for compression strength) A: Compression strength exceeds 0.2 MPa B: Compression strength is 0.2 MPa or lower

[0065] (Measurement of Apparent Density) The apparent density of the geopolimer hardened bodies of each example and comparative example was measured in accordance with JIS K7222.

[0066] (Evaluation Criteria for Apparent Density) A: 800 kg / m 3 Below B: 800 kg / m 3 Over 1060 kg / m 3 Below C: 1060 kg / m 3 Over

[0067]

Table 3

Industrial Applicability

[0068] Since the geopolimer hardened body and the heat insulating material of the present invention have more excellent heat insulating properties, they can be used as heat insulating materials for electronic components, heat insulating materials for heat storage devices used in various applications including houses, vehicles, industrial use, etc., heat insulating materials used in the engine room of automobiles, heat insulating materials used for heat preservation of the passenger compartment of automobiles, heat insulating materials covering fuel cells of automobiles, etc.

Claims

1. A composition for producing a diopolymer, comprising an aluminosilicate, inorganic particles, an activator, and water, wherein the inorganic particles are hollow particles.

2. A diopolymer cured body, comprising a diopolymer and inorganic particles, wherein the inorganic particles are hollow particles.

3. The diopolymer cured body according to claim 2, which is in a sheet form.

4. A heat insulating material comprising the diopolymer cured body according to claim 2.

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