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 have a BET specific surface area of 20 m2 / g or more. The geopolymer cured body comprises a geopolymer and inorganic particles, where the inorganic particles have a BET specific surface area of 20 m2 / g or more. 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 a heat insulating sheet 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 inventors conducted intensive studies and found 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, and the BET specific surface area of the inorganic particles is 20 m 2 / g or more.

[0008] In the composition for producing a geopolimer according to the above aspect, it is preferable that the inorganic particles are silica.

[0009] Another aspect of the present invention is a cured geopolimer. The cured geopolimer includes a geopolimer and inorganic particles, and the BET specific surface area of the inorganic particles is 20 m 2 / g or more.

[0010] In the cured geopolimer according to the above aspect, it preferably contains a geopolimer obtained using an acidic activator, and the surface temperature measured by the following heat insulation test is 350°C or lower. (Heat insulation test) Measure the surface temperature when a 3 mm thick cured geopolimer is heated on a hot plate at 500°C for 5 minutes.

[0011] In the cured geopolimer according to any of the above aspects, it is preferably in a sheet form.

[0012] Another aspect of the present invention is a heat insulating material. The heat insulating material preferably includes the cured geopolimer according to any of the above aspects.

Advantages of the Invention

[0013] 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 insulation properties; a cured geopolimer having more excellent heat insulation properties; and a heat insulating material including the cured geopolimer and having more excellent heat insulation properties.

Modes for Carrying Out the Invention

[0014] In this specification, unless otherwise specified, the notation "a~b" in the description of a numerical range represents that it is a or more and b or less.

[0015] 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 regarded as those described in this specification.

[0016] In this specification, "powdered particles" refers to an aggregate of "powder" or "particles".

[0017] The average particle diameter of the powder or particles {median particle diameter D50 (volume basis)} can be measured by a laser diffraction particle size distribution analyzer.

[0018] Unless otherwise specified, various measurements are carried out with the environmental temperature being room temperature (25°C).

[0019] 1. Composition for producing geopolymers The composition for producing geopolymers of this embodiment contains an 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.

[0020] A geopolymer refers to an amorphous polymer (polymer) of a material mainly composed of aluminum, silicon, etc., and is obtained by the reaction of an aluminosilicate and an activator described later.

[0021] 1-1. Aluminosilicate The aluminosilicate (xM2O·yAl2O3·zSiO2·nH2O, M is an alkali metal) of this embodiment is a compound having a structure in which a part of the silicon atoms in the silicate are replaced by aluminum atoms.

[0022] Examples of the aluminosilicate of the present embodiment 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; and the like. One or a mixture of two or more selected from these can be mentioned. Among them, calcined natural aluminosilicate minerals are preferable, and metakaolin is particularly more preferable.

[0023] Commercially available products of these substances can be used, and one or a combination of two or more of these can be used. 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.

[0024] Metakaolin, which is particularly preferable as the aluminosilicate of the present embodiment, is a compound represented by the chemical formula Al2O3·2SiO2. The content of metakaolin with respect 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 metakaolin with respect to the total mass of the aluminosilicate is within the above range, a geopolimer cured body excellent in strength can be stably obtained.

[0025] The powder or granules 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 or less. When the average particle diameter of the powder or granules is within this range, the heat insulation property of the produced geopolimer cured body can be further improved.

[0026] The content of the aluminosilicate is preferably 1% by mass or more, 5% by mass or more, 7% by mass or more, etc. with respect to the total mass of the composition for producing the dipolymer, and preferably 60% by mass or less, 55% by mass or less, 50% by mass or less, etc. with respect to the total mass of the composition for producing the dipolymer. By setting the content of the aluminosilicate within the above range, it is easy to increase the strength of the dipolymer cured body.

[0027] 1-2. Inorganic Particles The inorganic particles (inorganic filler) of the present embodiment are inorganic particles other than the above-described 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-described inorganic particles or a mixture of two or more kinds may be used.

[0028] The inorganic particles of the present embodiment preferably contain silicon dioxide (silica) in particular, and the content of silicon dioxide (silica) is preferably 90% by mass or more with respect to the total mass of the inorganic particles. Silica is mainly classified 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 dipolymer cured body can be improved.

[0029] The shape of the inorganic particles of the present embodiment is not particularly limited and may be spherical, amorphous, or flaky, with spherical being preferred. By making the inorganic particles spherical, the fluidity of the composition for producing the dipolymer after blending can be increased. The structure of the inorganic particles is not particularly limited, and a solid one is preferred.

[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 50 μm, and even more preferably in the range of 5 to 15 μm. The bulk density of the inorganic particles is preferably in the range of 0.001 to 1.000 g / cm 3 and more preferably in the range of 0.010 to 0.500 g / cm 3 and even more preferably in the range of 0.050 to 0.200 g / cm 3 . The method for measuring the bulk density is as follows.

[0031] (Method for Measuring Bulk Density) The bulk density is measured by the tapping method (ISO787-11). That is, the inorganic particles are put into a 250 mL graduated cylinder, and the bulk density is calculated using the volume value after tapping 1250 times.

[0032] In addition, the BET specific surface area of the inorganic particles is preferably 20 m 2 / g or more, 30 m 2 / g or more, 50 m 2 / g or more, etc., and preferably 500 m 2 / g or less, 450 m 2 / g or less, 400 m 2 / g or less, etc. By setting the BET specific surface area of the inorganic particles within the above range, unevenness is appropriately formed on the surface of the inorganic particles, so that the geopolimer cured body can easily take in air and the heat insulation property can be further improved. The method for measuring the BET specific surface area is as follows.

[0033] (Method for Measuring BET Specific Surface Area) The BET specific surface area is measured using a commercially available high-precision automatic gas adsorption device (manufactured by BEL Japan Inc., trade name BELSORP28), etc. In this case, nitrogen (N2) gas, which is an inert gas, is used as the adsorption gas.

[0034] Specifically, the adsorption amount Vm (cm 3 / g) required to form a monomolecular layer on the surface of the particles is measured, and the BET specific surface area S (m 2 / g) can be obtained from the following equation. S = 4.35 × Vm (m 2 / g)

[0035] The content of the inorganic particles is not particularly limited, and is preferably 5% by mass or more, 10% by mass or more, 20% by mass or more, 25% by mass or more, 30% by mass or more, etc., and preferably 60% by mass or less, 55% by mass or less, 50% 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 cured body of the geopolymers can be further improved.

[0036] 1-3. Activator The activator of the embodiment acts as a crosslinking agent when curing the composition for producing the geopolymers. The activator of the present embodiment is not particularly limited, and an alkali activator, an acid activator, etc. can be used. Examples of the alkali activator include substances containing alkali metal compounds such as sodium hydroxide and potassium hydroxide. Examples of the acid activator include phosphoric acid-based activators, nitric acid-based activators, sulfuric acid-based activators, etc. In the present embodiment, among these activators, an acid activator is preferable, and particularly, a phosphoric acid-based activator is more preferable. Hereinafter, the case of using a phosphoric acid-based activator as an example of the activator will be described.

[0037] In addition, even when an acid activator other than the phosphoric acid-based activator, an alkali activator, etc. 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 based on the total mass of the composition for producing the geopolymers 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.

[0038] The phosphoric acid-based activator used as the activator of the present 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- ) and the like. The phosphate reacts with water to form phosphate ions (PO4 3-)Any salt that releases, etc. may be used. For example, ammonium dihydrogen phosphate (NH4H2PO4), sodium dihydrogen phosphate (NaH2PO4), potassium dihydrogen phosphate (KH2PO4), ammonium hydrogen phosphate ((NH4)2HPO4), sodium hydrogen phosphate (Na2HPO4), etc. may be mentioned.

[0039] As a suitable example of the phosphate-based activator, an aqueous solution of high-concentration phosphoric acid may be mentioned. The phosphoric acid concentration of the aqueous solution of high-concentration phosphoric acid 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 aqueous solution of high-concentration phosphoric acid with the above phosphoric acid concentration, crosslinking and kneading can be efficiently performed.

[0040] When preparing the composition for producing a diopolymer, the ratio of the addition amount of the aqueous solution of high-concentration phosphoric acid 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.

[0041] The phosphoric acid concentration with respect to the total mass of the composition for producing a diopolymer is preferably, for example, 0.4 to 57.0% by mass, more preferably 0.8 to 38.2% by mass, and even more preferably 0.8 to 13.6% by mass.

[0042] If the phosphoric acid concentration with respect to the total mass of the composition for producing a diopolymer is within the above-described range, either an aqueous solution of high-concentration phosphoric acid or a phosphate may be used as the phosphate-based activator. Also, the order of mixing each component when preparing the composition for producing a diopolymer is not particularly limited.

[0043] Specifically, when using an aqueous solution of high-concentration phosphoric acid as the phosphate-based activator, the composition for producing a diopolymer may be prepared by adding it to a mixture of the solid components and water to be described later while stirring. Also, when using a phosphate as the activator, the composition for producing a diopolymer may be prepared by adding water to be described later to a mixture of the phosphate and the solid components.

[0044] 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.

[0045] 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 diopolymer is within the above-described range. A range of 5 to 50% by mass is preferable with respect to the total mass of the composition for producing the diopolymer.

[0046] 1-5. Other Components The composition for producing the diopolymer may contain other components as long as the effects of the present invention are not impaired. Examples of the other components include a pH adjuster, a fluidizing agent, a shrinkage reducing agent, a rust preventive agent, a waterproof material, a setting retarder, an antifoaming agent, a dust reducing agent, a pigment, and the like. Further, it may contain glass fibers or the like as a reinforcing material.

[0047] The content of the other components is not particularly limited, and a range of 1 to 10% by mass is preferable with respect to the total mass of the composition for producing the diopolymer.

[0048] 2. Diopolymer Hardened Body The diopolymer hardened body of this embodiment can be produced by mixing (kneading) each component of the above-described composition for producing the diopolymer and drying and curing it. That is, the diopolymer hardened body contains a diopolymer and inorganic particles.

[0049] The conditions for mixing each component of the composition for producing the diopolymer are not particularly limited as long as a diopolymer 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 perform curing 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.

[0050] The geopolymer cured body of this embodiment is preferably sheet-shaped. The heat insulating material provided with the sheet-shaped geopolymer cured body can be used for various applications (electronic components, moving bodies, etc.) described later.

[0051] The geopolymer cured body of this embodiment preferably has a compressive strength measured by a compression test (refer to the examples described later) of more than 2 MPa, 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.

[0052] The geopolymer cured body of this embodiment has an apparent density (refer to the examples described later) of 400 kg / m 3 or more, 500 kg / m 3 or more, 600 kg / m 3 or more, etc., preferably 1100 kg / m 3 or less, 900 kg / m 3 or less, 800 kg / m 3 or less, 700 kg / m 3 or less, etc. If the apparent density is within the above range, sufficient strength can be obtained even when the geopolymer cured body is formed into a sheet shape.

[0053] The surface temperature of the geopolymer cured body of this embodiment measured by a heat insulation test (refer to the examples described later) is preferably 350 °C or lower, 320 °C or lower, 310 °C or lower, etc. The heat insulation property of the geopolymer cured body of this embodiment can be evaluated by the heat insulation test.

[0054] In this embodiment, an example in which the geopolymer cured body is manufactured using the composition for manufacturing a geopolymer in the above-described manner is shown, but it is not limited thereto. That is, the geopolymer cured body of this embodiment may contain a geopolymer obtained using an acidic activator, as long as the surface temperature measured by the heat insulation test is within the above range.

[0055] 3. Applications of the heat insulating material The heat insulating material of the present embodiment preferably includes the above-described geopololymer 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 used as a heat insulating material for electronic components, a heat insulating material for heat storage devices used in various applications including housing, vehicles, and industrial use, a heat insulating material used in the engine room of an automobile, a heat insulating material used to keep the passenger compartment of an automobile warm, a heat insulating material for covering a fuel cell of an automobile, etc.

Example

[0056] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the embodiments below.

[0057] ≪Examples and Comparative Examples≫ <Preparation of Composition for Geopolymer Production> Each component of the composition for geopolymer production was prepared as follows. · Inorganic particles A to I shown in Tables 1 and 2 below · Metakaolin as an aluminosilicate {NN kaolin clay · manufactured by Takehara Chemical Industry Co., Ltd., heat-treated 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.}

[0058]

Table 1

[0059]

Table 2

[0060] The above-described solid components were mixed in the blending 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 geopolymer production. (Stirring Conditions) Mixer (Three-in-one motor BL600, manufactured by Shin-Toyo Kagaku Co., Ltd.) Rotation speed: 790 rpm, Stirring time: 20 minutes

[0061] <Manufacture of Geopolymer Hardened Body> The obtained composition for producing a geopolymer was cured under the following conditions. Specifically, the composition for producing a geopolymer 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 hardened bodies of the following Examples and Comparative Examples. (Heating conditions) Temperature: 120 °C, Time: 15 minutes (Curing conditions) Temperature: 23 °C, Relative humidity: 55%, Time: 24 hours

[0062] For the geopolymer hardened bodies of each Example and Comparative Example, a heat insulation test, a compression test, and measurement of apparent density (kg / m 3 ) were performed. The evaluation results are shown in Table 3 below.

[0063] (Heat insulation test) Test samples (thickness 3 mm, 100 φ) of the geopolymer hardened bodies of each Example and Comparative Example were heated on a 500 °C hot plate (C-MAG HP4, manufactured by IKA) for 5 minutes, and then the surface temperature at the center of each test sample was measured using a thermal image radiometer (FLIR TG167, manufactured by FLIR) from a height of 200 mm.

[0064] (Evaluation criteria for heat insulation) A: Surface temperature is 320 °C or lower B: Surface temperature exceeds 320 °C and is 350 °C or lower C: Surface temperature exceeds 350 °C

[0065] (Compression test) Test samples (thickness 3 mm, 10 φ) of the geopolymer hardened bodies of each Example and Comparative Example were subjected to full-surface compression at a compression speed of 1 mm / min using an autograph (AG-X 10 kN, manufactured by Shimadzu Corporation), and the compression strength until material failure was measured.

[0066] (Evaluation criteria for compressive strength) A: Compressive strength exceeds 2 MPa B: Compressive strength is 2 MPa or less

[0067] (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.

[0068]

Table 3

Industrial applicability

[0069] The geopolimer hardened body and heat insulating material of the present invention have more excellent heat insulating properties, and thus can be suitably used as heat insulating materials for electronic components, heat insulating materials for heat storage devices used in various applications including houses, vehicles, industrial uses, etc., heat insulating materials used in the engine room of automobiles, heat insulating materials used for heat preservation in the passenger compartment of automobiles, heat insulating materials covering fuel cells of automobiles, etc.

Claims

1. comprising an aluminosilicate, inorganic particles, an activator, and water, wherein the BET specific surface area of the inorganic particles is 20 m ２ / g or more, a composition for producing a diopolymer.

2. The composition for producing a diopolymer according to claim 1, wherein the inorganic particles are silica.

3. comprising a diopolymer and inorganic particles, wherein the BET specific surface area of the inorganic particles is 20 m ２ / g or more, a diopolymer cured body.

4. comprising a diopolymer obtained using an acidic activator, a diopolymer cured body having a surface temperature measured in the following heat insulation test of 350°C or less. (Heat insulation test) Measure the surface temperature when a 3 mm thick diopolymer cured body is heated on a hot plate at 500°C for 5 minutes.

5. The diopolymer cured body according to claim 3 or 4, which is in the form of a sheet.

6. A heat insulating material comprising the diopolymer cured body according to claim 3 or 4.

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