JP2018146098A - Manufacturing method of heat insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a heat insulating material capable of easily manufacturing a heat insulating material of high strength even through its weight is reduced, in a short time while securing sufficient heat insulation performance.SOLUTION: In a manufacturing method of a heat insulating material, a molding including fumed silica having a specific surface area of 50-400 m/g, reinforcement fiber having an average length of 0.3-20 mm and an average diameter of 0.3-20 μm, calcium hydroxide powder of an average particle grain size of 30 μm or less, and one or more kinds of binding agent selected from inorganic sol and aluminium lactate having an average grain size of 0.05 μm or less and solid content of 1-30 mass %, is heated to obtain the heat insulating material having 50% or less of a cumulative total pore volume of cumulative pore volume of pores of a pore diameter of 0.1 μm or less, and 10% or less of a cumulative total pore volume of cumulative pore volume of pores of a pore diameter of 10 μm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a heat insulating material.

  In a house, a building, a vehicle, a thermal insulation container, a refrigerator, a water heater, etc., a heat insulating material is used to reduce energy consumption by heat insulation. As the heat insulating material, for example, a heat insulating material containing silica fine particles and reinforcing fibers is known. Insulation materials are required to be lighter in order to improve handling. However, since the strength is reduced when the heat insulating material is reduced in weight, there are problems such as poor workability at the construction site and intense powder falling.

  Therefore, as a method for producing a heat-insulating material having high strength, a heat-insulating material containing silica fine particles, silica-based reinforcing fibers and calcium hydroxide is molded, and then cured under an environment of 80 ° C. and 90% relative humidity for 24 hours. A method for obtaining a heat insulating material has been proposed (Patent Document 1).

JP 2011-85216 A

  However, the manufacturing method of Patent Document 1 requires complex equipment for curing in a high-temperature and high-humidity environment, which increases process costs and requires a long time for manufacturing, and thus tends to reduce productivity.

  An object of this invention is to provide the manufacturing method of the heat insulating material which can manufacture the heat insulating material which has high intensity | strength easily and low cost in a short time, ensuring sufficient heat insulation performance, even if it reduces in weight.

The present invention has the following configuration.
[1] A method for producing a heat insulating material having a plurality of pores, comprising at least one selected from the group consisting of fumed silica, reinforcing fibers, calcium hydroxide powder, inorganic sol and aluminum lactate. Heat the molded body containing the binder,
The cumulative pore volume of pores having a pore diameter of 0.1 μm or less is 50% or less of the cumulative total pore volume, and the cumulative pore volume of pores having a pore diameter of 10 μm or more is 10% of the cumulative total pore volume. The manufacturing method of the heat insulating material which obtains the heat insulating material which is the following.
[2] The method for producing a heat insulating material according to [1], wherein a cumulative total pore volume in the heat insulating material is 1 to 4 cm ³ / g.
[3] The method for producing a heat insulating material according to [1] or [2], wherein the fumed silica has a specific surface area of 50 to 400 m ² / g.
[4] The method for manufacturing a heat insulating material according to any one of [1] to [3], wherein the reinforcing fiber has an average length of 0.3 to 20 mm and an average diameter of 0.3 to 20 μm.
[5] The method for producing a heat insulating material according to any one of [1] to [4], wherein the calcium hydroxide powder has an average particle size of 30 μm or less.
[6] The method for producing a heat insulating material according to any one of [1] to [5], wherein a particle diameter of the binder is 0.05 μm or less.
[7] The method for producing a heat insulating material according to any one of [1] to [6], wherein the total solid content of the binder is 1 to 30% by mass with respect to the total mass of the binder.
[8] The mass ratio of the total mass of the calcium hydroxide powder and the solid content of the binder to the total mass of the fumed silica and the reinforcing fiber in the molded body is 0.05 to 0.15. The manufacturing method of the heat insulating material in any one of [1]-[7].
[9] The heat insulation according to any one of [1] to [8], in which a mass ratio of the calcium hydroxide powder and the total solid content of the binder in the molded body is 2:10 to 10: 2. A method of manufacturing the material.
[10] The method for producing a heat insulating material according to any one of [1] to [9], wherein the inorganic sol is at least one selected from alumina sol or silica sol.
[11] When the total mass of the fumed silica and the reinforcing fibers in the molded body is 100 mass%, the ratio of the fumed silica is 50 to 99 mass%, and the ratio of the reinforcing fibers is 1 to 1. The manufacturing method of the heat insulating material in any one of [1]-[10] which is 30 mass%.
[12] The method for manufacturing a heat insulating material according to any one of [1] to [11], wherein the heating temperature of the molded body is 60 to 500 ° C.
[13] The method for manufacturing a heat insulating material according to any one of [1] to [12], wherein the heating time of the molded body is 0.2 to 10 hours.
[14] The method for manufacturing a heat insulating material according to any one of [1] to [13], wherein the forming method of the formed body is a press method.
[15] The method for producing a heat insulating material according to any one of [1] to [14], wherein the heat insulating material has a density of 0.15 to 0.5 g / cm ³ .

  According to the method for manufacturing a heat insulating material of the present invention, it is possible to manufacture a heat insulating material having high strength easily and at low cost in a short time while ensuring sufficient heat insulating performance and reducing the weight.

FIG. 14 shows the results of ²⁷ AlNMR measurement in Example 13.

  The method for manufacturing a heat insulating material of the present invention is a method for manufacturing a heat insulating material having a plurality of pores. In the method for producing a heat insulating material of the present invention, a molded article containing fumed silica, reinforcing fibers, calcium hydroxide powder, and a binder composed of at least one selected from the group consisting of an inorganic sol and aluminum lactate. Heat to obtain insulation. In the production method of the present invention, the cumulative pore volume of pores having a pore diameter of 0.1 μm or less is 50% or less of the cumulative pore volume, and the cumulative pore volume of pores having a pore diameter of 10 μm or more. Is obtained that has a cumulative pore volume of 10% or less.

Since fumed silica is an extremely fine powder, a specific surface area is usually used as an index representing the particle size.
The specific surface area of the fumed silica is preferably 50 to 400 m ² / g, more preferably ^{100~350m 2 / g, 200~300m 2 /} g is particularly preferred. If the specific surface area of fumed silica is not less than the lower limit of the above range, excellent heat insulating performance can be easily obtained. If the specific surface area of fumed silica is not more than the upper limit of the above range, it is easy to handle fumed silica. The specific surface area is measured by a nitrogen adsorption method (BET method).

  As the reinforcing fiber, a fiber that is usually used for a heat insulating material can be used, and examples thereof include a resin fiber and an inorganic fiber. Especially, an inorganic fiber is preferable from the point which is easy to suppress the fall of heat insulation performance and is excellent in heat resistance. As a reinforcing fiber, 1 type may be used independently and 2 or more types may be used together.

Examples of inorganic fibers include alumina fibers, mullite fibers, silica fibers, silica alumina fibers, zirconia fibers, alkaline earth metal silicate fibers, glass wool, glass fibers, rock wool, slag wool, silicon carbide fibers, carbon fibers, Examples thereof include silica alumina magnesia fiber, silica alumina zirconia fiber, silica magnesia calcia fiber, and basalt fiber.
The inorganic fiber is preferably a biosoluble fiber from the viewpoint of reducing adverse effects on the human body during the production or construction of the heat insulating material. The biosoluble fiber means an amorphous inorganic fiber that dissolves in a living body. Examples of the biosoluble fiber include alkaline earth silicate metal salt fibers.

  Examples of organic fibers include aramid fibers, polyethylene fibers, polypropylene fibers, polyolefin fibers, and the like.

The average length of the reinforcing fibers is preferably 0.3 to 20 mm, more preferably 0.5 to 10 mm, and further preferably 1 to 5 mm. When the average length of the reinforcing fibers is equal to or greater than the lower limit of the above range, a heat insulating material having high strength is easily obtained. If the average length of the reinforcing fibers is not more than the upper limit of the above range, the moldability is excellent.
The average length of the reinforcing fibers is an average value of the lengths measured for one arbitrarily selected reinforcing fiber.

The average diameter of the reinforcing fibers is preferably 0.3 to 20 μm, more preferably 0.5 to 15 μm, and further preferably 1 to 10 μm. When the average diameter of the reinforcing fibers is equal to or greater than the lower limit of the above range, a heat insulating material having high strength is easily obtained. If the average diameter of the reinforcing fiber is not more than the upper limit of the above range, the moldability is excellent.
In addition, the average diameter of a reinforcing fiber is an average value of the diameter measured about ten arbitrarily selected reinforcing fibers.

  The average particle size of the calcium hydroxide powder is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less. If the average particle diameter of the calcium hydroxide powder is less than or equal to the upper limit of the above range, defects are unlikely to occur, and a heat insulating material having high strength is easily obtained. The lower limit of the average particle diameter of the calcium hydroxide powder is not particularly limited, but it is easy to obtain and use if it is 1 μm or more.

  The particle size of the binder composed of at least one selected from the group consisting of inorganic sol and aluminum lactate (hereinafter referred to as binder) is preferably 0.05 μm or less, more preferably 0.03 μm or less, and 0.02 μm. The following is more preferable. If the particle size of the binder is not more than the upper limit of the above range, a heat insulating material with high strength can be easily obtained. The lower limit of the particle size of the binder is not particularly limited, but it is easy to obtain and use if it is 0.0001 μm or more. The upper limit of the particle size when the binder is composed of two or more types is the value of the particle size of the binder having the largest particle size.

  The solid content of the binder is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and still more preferably 5 to 20% by mass with respect to the total mass of the binder. If the solid content of the binder is equal to or greater than the lower limit of the above range, it is easy to suppress the formation of fumed silica lump due to excessive water content when the raw materials are mixed. Therefore, fumed silica is easily dispersed uniformly, and excellent heat insulation performance is easily obtained. The solid content of the binder when two or more binders are used is obtained by dividing the total solid content of each binder by the total mass of the binder. If the solid content of the binder is equal to or less than the upper limit of the above range, a sufficient amount of water is ensured, whereby the reaction between the calcium hydroxide powder and the binder is likely to proceed, and a high-strength heat insulating material is easily obtained.

Examples of the inorganic sol include colloids having a hydrophilic group on the surface. Examples of such colloids include various oxides such as silica, alumina, ceria, titania, magnesia, yttria, and zirconia. Of these, silica sol and alumina sol, which are colloids of silica and alumina, are preferred.
As aluminum lactate, aluminum lactate normal salt (Al (OCOCH (OH) CH ₃ ) ₃ ), basic aluminum lactate (Al (OH) (OCOCH (OH) CH ₃ ) ₂ , Al (OH) ₂ (OCOCH (OH) ) CH ₃ )) and hydrates thereof. It is preferable to use basic aluminum lactate as an aqueous solution in advance.

  In addition, although it is known that basic aluminum lactate is desorbed by heating to become alumina, the ratio of the alumina sol is the ratio at the time of mixing the raw materials.

  In the present invention, when the total mass of fumed silica and reinforcing fibers in the molded body is 100% by mass, the ratio of fumed silica is 50 to 99% by mass, and the ratio of reinforcing fibers is 1 to 50% by mass. Preferably there is. When the ratio of fumed silica and reinforcing fibers is within the above range, a heat insulating material having excellent heat insulating performance is easily obtained.

The proportion of fumed silica in the molded body is preferably 50 to 99% by mass, more preferably 55 to 90% by mass, and 60 to 85% by mass with respect to 100% by mass of the total mass of fumed silica and reinforcing fibers. Further preferred.
The proportion of the reinforcing fibers in the molded body is preferably 1 to 50% by mass, more preferably 3 to 25% by mass, and further 5 to 20% by mass with respect to 100% by mass of the total mass of fumed silica and reinforcing fibers. preferable.

When a radiation inhibitor is included in the molded body, it is preferable to include a radiation inhibitor because a heat insulating material having excellent high-temperature heat insulating properties can be easily obtained.
Examples of the radiation inhibitor include metal particles (aluminum particles, silver particles, gold particles, etc.), inorganic particles (graphite, carbon black, silicon carbide, titanium oxide, tin oxide, iron oxide, potassium titanate, etc.). It is done. As a radiation inhibitor, 1 type may be used independently and 2 or more types may be used together.

  When the radiation inhibitor is included in the molded body, the ratio of fumed silica is 50 to 95 mass% when the total amount of fumed silica, reinforcing fiber and radiation inhibitor in the molded body is 100 mass%. The ratio of the reinforcing fibers is preferably 1 to 30% by mass, and the ratio of the radiation inhibitor is preferably 3 to 30% by mass.

Solid content (mass: W _E ) of calcium hydroxide powder (mass: W _D ) and binder relative to the total mass of fumed silica (mass: W _A ) and reinforcing fibers (mass: W _B ) in the molded body The mass ratio (W _D + W _E ) / (W _A + W _B ) of the total mass is preferably 0.05 to 0.15. When the mass ratio (W _D + W _E ) / (W _A + W _B ) is equal to or higher than the lower limit of the above range, a heat insulating material having high strength is easily obtained. When the weight ratio _{(W D + W E) /} (W A + W B) is more than the upper limit of the range, it is easy to obtain the heat insulating material having an excellent heat insulation performance. _{However, W A, W B, W} D, W E must not be 0.

Weight ratio _W D of the solid content of the calcium powder and connecting agent hydroxide in the compact: _{W E} is 2: 10 to 10: 2 is preferred, 3: 10 to 10: 3, more preferably, 4: 10 10: 4 is more preferable. Weight ratio W _D: if W _E is within the above range, the heat insulating material is easily obtained with high strength.

The method for obtaining the molded body is not particularly limited. For example, a mixed raw material containing fumed silica, reinforcing fibers, radiation inhibitor, calcium hydroxide powder, and a binder is put into a mold and pressed. And a pressing method, a casting method and an extrusion method.
When the molding method of the molded body is a pressing method, it is easy to adjust the cumulative pore volume of the heat insulating material by controlling the pressing pressure. The molding pressure may be adjusted while looking at the density of the molded body.
The method of mixing each raw material is not particularly limited, and examples thereof include a method of stirring using a blender or the like. The mixing order of fumed silica, reinforcing fiber, radiation inhibitor, calcium hydroxide powder and binder is not particularly limited.

  What is necessary is just to set the shape of a molded object suitably according to a use, for example, plate shape etc. are mentioned. What is necessary is just to set the dimension of a molded object suitably according to a use.

In the production method of the present invention, a heat insulating material is obtained by heating a molded body containing fumed silica, reinforcing fibers, a radiation inhibitor, calcium hydroxide powder, and a binder. By heating the compact, it is considered that the calcium hydroxide powder and the binder react, and the reaction product functions as a binder to obtain a heat insulating material with high strength.
Specifically, when an alumina sol is described as an example of the binder, the calcium ion generated from the calcium hydroxide powder and the aluminate generated from the alumina sol react with each other as shown in the following formula. It is considered that calcium aluminate hydrate (3CaO · Al ₂ O ₃ · 6H ₂ O) functions as a binder.
Further, by heating the molded body, moisture in the molded body is removed and dried while the calcium hydroxide powder and the alumina sol react.

  Similarly, when the binder is other inorganic sol or aluminum lactate, it is considered that calcium hydroxide and the binder react to form a hydrate and function as a binder.

The method for heating the molded body is not particularly limited, and examples thereof include an electric furnace.
The heating temperature of the molded body is preferably 60 to 500 ° C, more preferably 80 to 400 ° C, and further preferably 100 to 300 ° C. When the heating temperature is at least the lower limit of the above range, the reaction between the calcium hydroxide powder and the alumina sol is likely to proceed sufficiently, and a high-strength heat insulating material is likely to be obtained. If heating temperature is below the upper limit of the said range, it is not necessary to use a complicated apparatus for heating a molded object, and it can implement more simply.

  The heating time of the molded body is preferably 0.2 to 10 hours, more preferably 0.5 to 8 hours, and further preferably 1 to 5 hours. When the heating time is at least the lower limit of the above range, the reaction between the calcium hydroxide powder and the alumina sol is likely to proceed sufficiently, and a heat-insulating material having high strength can be easily obtained. When the heating time is not more than the upper limit of the above range, the heat insulating material can be produced with high productivity.

The heat insulating material obtained by the production method of the present invention has pores. Cumulative total pore volume in the resulting heat insulating material is preferably 1 to 4 cm ³ / g, and more preferably 2~3.8cm ³ / g. When the cumulative total pore volume is not less than the lower limit, the heat insulating performance is good, and when it is not more than the upper limit, the strength is easily maintained even if the density is lowered.

In the heat insulating material obtained by the production method of the present invention, the cumulative pore volume of pores having a pore diameter of 0.1 μm or less is 50% or less of the cumulative total pore volume in the heat insulating material, and the pore diameter is The cumulative pore volume of pores of 10 μm or more is 10% or less of the cumulative total pore volume in the heat insulating material.
The cumulative pore volume of pores having a pore diameter of 0.1 μm or less is preferably 40% or less of the cumulative total pore volume in the heat insulating material, and the cumulative pore volume of pores having a pore diameter of 10 μm or more is in the heat insulating material. It is preferably 5% or less of the cumulative total pore volume.
If the ratio of the cumulative pore volume of pores having a pore size of 0.1 μm or less is larger than the above upper limit value, the density of the heat insulating material tends to increase, and the heat conductivity due to the heat conductivity due to the heat transfer of the solid tends to increase. Tends to get worse. On the other hand, when the ratio of the cumulative pore volume of pores having a pore diameter of 10 μm or more is larger than the lower limit value, the handling property of the heat insulating material is poor and it is easily broken.

  In order to control the pore diameter of the pores, a pore-imparting material may be added to the molded body. The pore-imparting material can be burned down by heat treatment to form pores, has a certain particle size, and can be used for the production of a ceramic porous body. For example, resin powder such as polymethyl methacrylate, cellulose, pulp, sawdust and the like can be used.

Density of insulation material to be produced by the production method of the present invention is preferably 0.15~0.5g / cm ^3, more preferably 0.2~0.4g / cm ^3, 0.25~0.35g / cm ³ is more preferable. If the density of the molded body is not less than the lower limit of the above range, sufficient strength can be easily obtained. When the density of the molded body is equal to or less than the upper limit of the above range, excellent heat insulating performance can be easily obtained and the weight is light.
The density of the heat insulating material can be adjusted, for example, by controlling the pressing pressure during molding.

The shrinkage when the heat insulating material is heated at 800 ° C. for 1 hour is preferably 3% or less, more preferably 2% or less, and further preferably 1.5% or less. If the said shrinkage | contraction rate of a heat insulating material is below the said upper limit, it has the outstanding heat resistance.
The shrinkage rate of the heat insulating material can be calculated from the volume of the heat insulating material before and after heating. The shrinkage rate of the heat insulating material can be adjusted by adjusting the composition.

As described above, in the method for producing a heat insulating material of the present invention, a heat insulating material is obtained by heating a molded body containing reinforcing fibers, calcium hydroxide powder, and a binder. Therefore, a heat insulating material having high strength can be obtained while ensuring excellent heat insulating performance. This is because, for example, alumina sol is used as a binder as an example, because calcium aluminate hydrate produced by the reaction of calcium ions generated from calcium hydroxide powder with aluminate during heating functions as a binder. It is believed that there is.
In addition, the method for manufacturing a heat insulating material according to the present invention does not require a complicated apparatus because it does not need to control humidity conditions as compared with a conventional manufacturing method such as Patent Document 1, and is simple and low-cost. Moreover, a heat insulating material can be manufactured in a short time without requiring a long-term curing.

  The use of the heat insulating material obtained by the present invention is not particularly limited. For example, residential and building walls / roof / floor / piping, solar / heat facilities, etc., constant temperature bath, water heater, hot water tank, Rice cookers, refrigerators, freezers, cold storage / cooling tanks, vending machines, cooler boxes, cold covers, thermal insulation such as winter clothes, electricity / electronics such as laptop computers, LCD projectors, photocopiers, batteries, fuel cells The present invention can be applied to industrial equipment fields such as equipment and semiconductor manufacturing equipment, and mobile fields such as automobiles, buses, trucks, cold cars, trains, freight cars, and ships.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by the following description. Examples 1 to 5, 10, and 11 are examples, examples 6 to 9 are comparative examples, and example 12 is an experimental example.
[density]
The dimension and mass of the heat insulating material of each example were measured, and the density (g / cm ³ ) of the heat insulating material was calculated. In addition, the density was calculated | required as an average value of the density of eight heat insulating materials.

[Bending strength]
About the heat insulating material of each example, bending strength (kPa) was measured by 3 point | piece bending of the span 30mm using the Shimadzu Corporation autograph. In calculating the bending strength, the maximum load value of the stress-strain curve was adopted. Moreover, bending strength was calculated | required as an average value of the density of eight heat insulating materials.

[Thermal conductivity]
About the heat insulating material of each example, the heat conductivity was measured by the heat flow meter method which made the high temperature part 30 degreeC and the low temperature part 20 degreeC using the heat conductivity measuring apparatus.

[ ²⁷ AlNMR measurement]
^{The 27} AlNMR measurement was performed by ²⁷ AlMAS NMR method using an NMR apparatus (ECA600) manufactured by JEOL.

[Cumulative pore volume]
The cumulative pore volume of the heat insulating material was measured with a mercury pressure porosimeter. The cumulative pore volume of all the obtained pores is defined as the cumulative total pore volume, and the cumulative pore volume of pores having a pore diameter of 0.1 μm or less and the cumulative pore volume of pores having a pore diameter of 10 μm or more are respectively calculated. The ratio was calculated.

[material]
The raw materials used in this example are shown below.
A-1: Fumed silica (manufactured by Cabot, CAB-O-SIL (registered trademark) H-300, specific surface area: 300 m ² / g),
B-1: Biosoluble fiber (manufactured by New Nippon Thermal Ceramics, super wool, length: several μm to several tens of mm, average diameter: 3 μm),
C-1: Silicon carbide powder (manufactured by Yakushima Electric Works, GC-4000F, average particle size: 2.5 μm),
D-1: Calcium hydroxide powder (manufactured by Ube Materials, CH-2N, average particle size: 5.7 μm),
E-1: Alumina sol (manufactured by Taki Chemical Co., Ltd., Viral (registered trademark) Al-ML15, primary particle size: ≦ 5 nm, solid content: 15% by mass),
E-2: Basic aluminum lactate (manufactured by Taki Chemical Co., Ltd., Taxelum (registered trademark) M-160L, primary particle size: ≦ 1 nm, solid content: 8.7% by mass),
X-1: Aluminum hydroxide powder (manufactured by Wako Pure Chemical Industries, reagent aluminum hydroxide powder).
[Examples 1 to 9]
Each raw material is mixed with a blender with the composition shown in Table 1, and the pressing pressure is adjusted by a pressing method using a mold so that the density is about 0.25 g / cm ³ , and the dimensions are 20 mm long × 40 mm wide. X Eight molded articles having a thickness of 5 mm were produced. The obtained molded body was heated at 200 ° C. for 2 hours to obtain a heat insulating material.
The cumulative total pore volume of the heat insulating material obtained in Example 1 is 3.6 cm ³ / g, and the ratio of the cumulative pore volume of pores having a pore diameter of 0.1 μm or less to the cumulative total pore volume is 24.7%. The ratio of the cumulative pore volume of pores having a pore diameter of 10 μm or more to the cumulative total pore volume was 5.8%.

Table 1 shows the measurement results of the density and bending strength of the heat insulating material in each example. The numerical value in parentheses in the column of alumina sol in Table 1 is the solid content. The amount of _{W A} fumed silica (g), _{W B} is the amount of the reinforcing fibers (g), the amount of _{W C} is radiant inhibitor (g), _{W D} is the amount of calcium hydroxide powder (g), _{W E} is the amount of the connecting agent (solid content) (g).

As shown in Table 1, the heat insulating materials of Examples 1 to 5 manufactured by the manufacturing method of the present invention had high bending strength.
On the other hand, the heat insulating materials of Examples 6 and 7 not using calcium hydroxide powder, Example 8 not using a binder, and Example 9 using aluminum hydroxide powder instead of the binder are all low in bending strength, The strength was inferior.

[Examples 10 and 11]
Each raw material is mixed with a blender with the composition shown in Table 1, and the pressing pressure is adjusted by a pressing method using a mold so that the density is about 0.28 to 0.29 g / cm ³ , and the dimensions are vertical. Eight molded bodies of 125 mm × width 125 mm × thickness 10 mm were produced. The obtained molded body was heated at 200 ° C. for 2 hours to obtain a heat insulating material.
The mixing ratio of each raw material in Example 10 is the same as the mixing ratio in Example 1, and the mixing ratio of each raw material in Example 11 is the same as the mixing ratio in Example 3.
The cumulative total pore volume of the heat insulating material obtained in Example 10 is 3.0 cm ³ / g, and the ratio of the cumulative pore volume of pores having a pore diameter of 0.1 μm or less to the cumulative total pore volume is 31.6%. Yes, the ratio of the cumulative pore volume of pores having a pore diameter of 10 μm or more to the cumulative total pore volume was 7.5%.

Table 2 shows the measurement results of the heat insulating material density and thermal conductivity in each example. The numerical values in parentheses in the column of alumina sol or basic aluminum lactate in Table 1 are solid contents. In _addition, W A ~W _E is the same as in Table 1.

  As shown in Table 2, the heat insulating materials of Examples 10 and 11 manufactured by the manufacturing method of the present invention had low thermal conductivity and excellent heat insulating performance.

[Example 12]
9.6 g of fumed silica (A-1), 1.2 g of reinforcing fiber (B-1), 1.2 g of radiation inhibitor (C-1), and 4 g of alumina sol (E-1) (solid content 0.6 g) Were mixed with a blender, and a compact was produced by adjusting the pressing pressure so that the density was about 0.25 g / cm ³ by a pressing method using a mold. Next, the molded body was heated at 200 ° C. for 2 hours to obtain a heat insulating material. A small piece was cut out from the heat insulating material to prepare Sample-1.
Further, Sample-2 was produced in the same manner as Sample-1, except that 0.6 g of calcium hydroxide powder (D-1) was added.
Alumina sol (E-1) was designated as Sample-3.
²⁷ AlNMR measurements were performed on each sample. The results are shown in FIG.

  As shown in FIG. 1, in the spectrum of Sample-3, a 4-coordinate Al-derived peak a was confirmed in the vicinity of 60 to 70 ppm, and a broad peak b was confirmed in the vicinity of 0 to −30 ppm. In the spectrum of Sample-1 containing fumed silica (A-1), reinforcing fiber (B-1), radiation inhibitor (C-1) and alumina sol (E-1), peak a and peak derived from alumina sol Both b were confirmed. On the other hand, in the spectrum of Sample-2 to which calcium hydroxide powder (D-1) was further added, peak a and peak b derived from alumina sol disappeared. Thereby, it was confirmed that calcium hydroxide powder and alumina sol were reacted by heating.

Claims (15)

A method for producing a heat insulating material having a plurality of pores,
Heating a molded body containing fumed silica, reinforcing fibers, calcium hydroxide powder, and a binder composed of at least one selected from the group consisting of inorganic sols and aluminum lactate,
The cumulative pore volume of pores having a pore diameter of 0.1 μm or less is 50% or less of the cumulative total pore volume, and the cumulative pore volume of pores having a pore diameter of 10 μm or more is 10% of the cumulative total pore volume. The manufacturing method of the heat insulating material which obtains the heat insulating material which is the following. The manufacturing method of the heat insulating material of Claim 1 whose cumulative total pore volume in the said heat insulating material is 1-4 cm < ³ > / g. The manufacturing method of the heat insulating material of Claim 1 or 2 whose specific surface area of the said fumed silica is 50-400 m < ² > / g.   The manufacturing method of the heat insulating material as described in any one of Claims 1-3 whose average length of the said reinforcement fiber is 0.3-20 mm, and whose average diameter is 0.3-20 micrometers.   The manufacturing method of the heat insulating material as described in any one of Claims 1-4 whose average particle diameter of the said calcium hydroxide powder is 30 micrometers or less.   The manufacturing method of the heat insulating material as described in any one of Claims 1-5 whose particle size of the said binder is 0.05 micrometer or less.   The manufacturing method of the heat insulating material as described in any one of Claims 1-6 whose sum total of the solid content of the said binder is 1-30 mass% with respect to the total mass of the said binder.   The mass ratio of the total mass of the solid content of the calcium hydroxide powder and the binder to the total mass of the fumed silica and the reinforcing fiber is 0.05 to 0.15. The manufacturing method of the heat insulating material of one term.   The manufacturing method of the heat insulating material as described in any one of Claims 1-8 whose mass ratio of the said calcium hydroxide powder in the said molded object and the sum total of the solid content of the said binder is 2: 10-10: 2. Method.   The manufacturing method of the heat insulating material as described in any one of Claims 1-9 whose said inorganic type sol is 1 or more types chosen from an alumina sol or a silica sol.   When the total mass of the fumed silica and the reinforcing fiber in the molded body is 100% by mass, the ratio of the fumed silica is 50 to 99% by mass, and the ratio of the reinforcing fiber is 1 to 30% by mass. The manufacturing method of the heat insulating material as described in any one of Claims 1-10 which is these.   The manufacturing method of the heat insulating material as described in any one of Claims 1-11 whose heating temperature of the said molded object is 60-500 degreeC.   The manufacturing method of the heat insulating material as described in any one of Claims 1-12 whose heating time of the said molded object is 0.2 to 10 hours.   The manufacturing method of the heat insulating material as described in any one of Claims 1-13 whose molding method of the said molded object is a press method. The manufacturing method of the heat insulating material as described in any one of Claims 1-14 whose density of the said heat insulating material is 0.15-0.5 g / cm < ³ >.

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