JP6188245B2 - Insulating material and method of manufacturing the insulating material - Google Patents

Description

  The present invention relates to a heat insulating material having heat insulating properties and a method for manufacturing the heat insulating material.

  Refrigerated and frozen products such as pharmaceuticals and food products are usually corrugated cardboard with insulation such as foamed polystyrene containers and urethane foam that have heat insulation properties in environments other than refrigerated and frozen conditions to prevent quality deterioration during transportation. It is housed and transported in an insulated container (for example, Patent Document 1) such as a box. Since such a heat insulating container is bulky as compared with the product to be stored, there has been a problem that the transportation cost of the product is increased. In addition, it is essential to prepare an insulated container separately from the product itself, and to store and pack the product, which has been a factor in complicating the transportation procedure.

  On the other hand, there are many occasions where a container for keeping a product at a high temperature for a relatively long time is required. Such a container is often required to be touched with a bare hand at the same time as the outside does not become hot at the time of use. As such a container, a bulky material container such as foamed polystyrene, a paper container having a laminated structure on the side wall, or the like is used in order to provide heat retention. As a paper container having a laminated structure on the side wall, for example, a paper container having an air layer inside the laminated side wall is known as in Patent Document 2. In any case, the whole is bulky as compared with the inner volume, and a large space is required for transporting and storing the container itself.

Japanese Patent Laid-Open No. 11-147777 JP 2000-247377 A JP 7-48881 A

  As described above, since most of the conventional heat insulating materials in each field are bulky, it has been a factor of lowering transport efficiency and storage efficiency. In addition, the materials used are limited to glass wool, heat insulation board, foamed urethane, foamed polystyrene, etc., and due to their thickness and structural weakness, fine processing and molding are difficult, and box-shaped heat insulation containers Moreover, the object used, such as a comparatively large base material, was limited.

  Therefore, an object of the present invention is to provide a heat insulating material that is less bulky than the prior art, has excellent processability, and can be applied to a fine structure.

The heat-insulating material of the present invention that solves the above problems is a binder comprising main fibers, airgel, at least one water-soluble polymer selected from the group consisting of cationic polymers and amphoteric polymers, and / or low-melting synthetic fibers. Wherein the airgel has a density of less than 0.5 g / cm ³ and a thermal conductivity of 0.02 W / (m · K) or less, based on 100 parts by weight of the main fiber. The airgel is blended in an amount of 35 to 210 parts by weight.
The heat insulating material of the present invention having the above-mentioned structure is low in bulk like ordinary paper and has excellent workability, and in addition, it has a low density and low thermal conductivity aerogel blended in a certain amount, providing excellent heat insulation. Have sex. Moreover, the heat insulating material of the present invention contains at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, and / or a low-melting synthetic fiber as a binder in addition to the main fiber and airgel. . By containing the binder, there is an effect that the particle shape of the airgel is less likely to be collapsed in the paper making process and the heat insulation is easily maintained.
Here, the “density” refers to that measured in the state of particles at 25 ° C. and 1 atm. The “aerogel” referred to here is a fine particle having a continuous matrix of a solid material having many nanometer-scale pores from which air is dispersed. Furthermore, in the present invention, “parts by weight” is based on dry weight except for water.
The “low-melting-point synthetic fiber” as used herein means a synthetic fiber having a melting point lower than the melting point when the main fiber has a melting point at least 140 ° C. at least on the surface of the fiber. Shall point to.

The binder preferably contains the water-soluble polymer, and the water-soluble polymer is preferably at least one of cationized starch and amphoteric starch. By using cationized starch or amphoteric starch as a binder, the particle shape of the airgel at the time of papermaking is more difficult to break, and the heat insulating performance of the heat insulating material using this can be maintained.
The binder preferably includes the low-melting synthetic fiber, and the low-melting synthetic fiber is a vinylon binder fiber. By using a vinylon binder fiber as a binder, a heat insulating material can be produced efficiently.

  The airgel is preferably porous silica particles obtained by air-gelling methyl silicate monomer by atmospheric pressure drying or critical drying. The normal pressure dried gel or critical dried gel of methyl silicate is easy to produce at low density, and since the porous shape does not easily collapse in an aqueous solution, the shape is easily retained in the papermaking slurry.

It is preferable that the airgel has an average particle diameter of 2 to 140 μm and a specific surface area of 400 m ² / g or more. By setting the average particle size of the airgel to 2 to 140 μm, the heat insulating material can be provided with sufficient heat insulating properties, and the heat insulating performance can be exhibited even in a heat insulating material having a low bulk. Moreover, it becomes possible to provide higher heat insulation to a heat insulating material by the specific surface area of porous silica activation being 400 m < ² > / g or more.

The heat insulating material of the present invention is preferably in the form of a sheet having a thickness of 15 μm to 1.2 cm, a basis weight of 10 to 480 g / m ² , and a density of 0.5 to 1.5 g / cm ³ . By making a heat insulating material into the said property, paper-like texture and workability can be given.

The heat insulating material manufacturing method of the present invention includes 100 parts by weight of main fibers, 35 to 210 parts by weight of airgel having a density of less than 0.5 g / cm ³ and a thermal conductivity of 0.02 W / (m · K) or less, At least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer and / or 0.3 to 125 parts by weight of a binder containing a low-melting synthetic fiber are added to water and mixed to obtain a mixed slurry. The mixed slurry is prepared and paper-made. According to the above production method, it is possible to produce a heat insulating material having an excellent heat insulating property in addition to having a low bulk as in ordinary paper and having excellent workability.

  In the manufacturing method of the heat insulating material of this invention, it is preferable that the said mixing slurry at the time of papermaking shall be pH 7-8. In a slurry having a pH of 7 to 8, the characteristics and properties of the airgel are easily stabilized, and at the same time, when the main fiber contains pulp, fibrillation is easily promoted.

  Further, in the method for manufacturing a heat insulating material of the present invention, the binder of the mixed slurry contains the water-soluble polymer, and the water-soluble polymer and the airgel are added and mixed into a slurry in which at least the main fiber is suspended in water. It is preferable to adjust the mixed slurry. This is because airgel and fiber composites are formed by entanglement of the airgel with the fibers, and it becomes difficult to float on the water surface.

  The heat insulating material of the present invention has sufficient heat insulating properties, is low in bulk, and has excellent workability. Moreover, the manufacturing method of the heat insulating material of this invention can provide the heat insulating material which was low in bulk and excellent in workability, maintaining sufficient heat insulation.

  Hereinafter, the heat insulating material of the present invention and the method for producing the heat insulating material will be exemplarily described.

1. Thermal insulation The thermal insulation of the present invention comprises a main fiber, an airgel, at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, and / or a binder containing a low-melting synthetic fiber. The airgel has a density of less than 0.5 g / cm ³ and a thermal conductivity of 0.02 W / (m · K) or less, and the airgel with respect to 100 parts by weight of the main fiber. Is blended in an amount of 35 to 210 parts by weight. Hereafter, each compounding component of the said heat insulating material is explained in full detail.

<Main fiber>
As the main fiber of the heat insulating material of the present invention, either a synthetic fiber or a natural fiber can be used. When synthetic fibers are used, the main fibers are not particularly limited. For example, polyester fibers, vinylon fibers, olefin fibers, polyurethane fibers, aramid fibers, which are synthetic fibers that are usually used as raw materials for nonwoven fabrics. Acrylic fiber, polylactic acid fiber, polyvinyl chloride fiber, vinylidene fiber, polyphenylene sulfide fiber, ceramic fiber, alumina fiber, glass fiber can be used, polyester fiber is preferable, polyethylene terephthalate (hereinafter referred to as PET) fiber Is more preferable.
Moreover, when using a natural fiber, although it does not specifically limit as a main fiber, For example, a pulp can be used. The type of pulp is not particularly limited, and any of wood pulp, non-wood pulp, and deinked pulp, which are usually used as raw materials for paper, can be used. Chemical pulp, semi-chemical pulp, mechanical pulp Any pulp can be used.
The selection of various main fibers can be appropriately changed according to the desired flexibility, heat resistance, flame retardancy, non-flammability, flexibility, strength, and weight of the heat insulating material. Only one type of fiber can be contained, or a plurality of types of fibers can be contained.

In particular, in the heat insulating material of the present embodiment containing a large amount of airgel, which will be described later, for example, when only pulp is used as the main fiber, the strength tends to be low although it has high heat insulating properties. In this case, the microfibrillated pulp (cellulose nanofiber) is blended in the main fiber in an amount of 0.5 to 22 parts by weight based on 100 parts by weight of all the main fibers, while maintaining the high heat insulating property of the heat insulating material. , Paper-like strength and workability can be imparted.
In a heat insulating material containing a large amount of airgel, which will be described later, a synthetic fiber having a small fiber diameter is desirable in order to retain the airgel.

<Aerogel>
The airgel used in the present invention is a fine particle having a continuous matrix of solid material from which a large number of nanometer-scale pores are dispersed and from which air is dispersed. For example, 99% is composed of air and is extremely light and effective. It becomes a proper heat insulating material. As the airgel, known silica compounds such as silica, methyl silicate and silica / alumina, and porous particles such as resorcinol / formaldehyde, cellulose and cellulose nanofiber airgel can be used. Regardless of the degree of porosity, the thermal conductivity of the material itself is 0.15 W / (m · K) or less, particularly 0.1 W / (m · K) or less, and further 0.06 to 0.018 W / ( m · K) is preferably used. In particular, a product obtained by aerogelating methyl silicate monomer by atmospheric pressure drying or critical drying is easy to produce at a low density, can form a nano-level porous structure or hollow structure relatively easily, and an aqueous solution It can be suitably used because it is difficult to disintegrate.

  The porosity of the airgel is preferably 50.0 to 99.8%, particularly preferably 70 to 99.8%, and more preferably 86 to 99.8%. The average particle diameter is not particularly limited, but is preferably 2 to 140 μm. When the particle diameter of the porous silica particle airgel is more than 140 μm, it is necessary to increase the thickness of the heat insulating material, and it is difficult to achieve the object of the present application to provide a heat insulating material agent having a low volume and a heat insulating effect. Further, if it is less than 2 μm, it is difficult to obtain a sufficient heat insulating effect.

Airgel has a specific surface area of 400 meters ² / g or more, particularly 500 to 1000 m ² / g, it is preferable to further use those 600~1000m ² / g. By increasing the specific surface area, the porosity can be increased. Moreover, the weight of the whole heat insulating material can also be reduced.

It is preferable that the compounding quantity of the airgel in the heat insulating material of this invention shall be 35-210 weight part with respect to 100 weight part of main fibers. If the blending amount of the airgel is less than 35 parts by weight, there is a possibility that sufficient heat insulating properties cannot be given to the heat insulating material. Further, if the blending amount of the airgel exceeds 210 parts by weight, the strength of the heat insulating material decreases, it becomes difficult to obtain the desired paper-like processability, the airgel is detached from the heat insulating material, scattering, etc. Problems can arise.
In the case where the main fiber contains pulp and the binder described below contains at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, from the same viewpoint, It is preferable to set it as 35-75 weight part with respect to 100 weight part of fibers, It is preferable to set it as 35-60 weight part especially 38-52 weight part especially.

<Binder>
The heat insulating material of the present invention contains at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, and / or a binder containing low-melting synthetic fibers. That is, the binder contained in the heat insulating material of the present invention includes at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, and / or a low melting point synthetic fiber. As the water-soluble polymer, those obtained by cationizing and / or amphotericizing starch, polyvinyl alcohol (PVA), polyvinyl acetate, aqueous urethane and the like can be preferably used. In particular, at least one of cationized starch and amphoteric starch can be used more suitably because bubbles are not easily generated in the aqueous solution during paper making, and stable paper making and high yield are possible.
The cationized starch and the amphoteric starch can be carried out by using a known method described in, for example, JP-A No. 2003-64101 (cationized starch), JP-A No. 2001-19701 (amphoteric starch) and the like. . In addition, what is marketed can use a cationic starch suitably, for example, Nippon Food Chemical Co., Ltd. Neotuck series etc. are applicable.

The low melting point synthetic fiber has a melting point of 140 ° C. or lower at least on the surface of the fiber, and is lower than the melting point when the main fiber has a melting point (for example, when the main fiber contains a synthetic fiber). It is not particularly limited as long as it is a synthetic fiber having a melting point, and as the low melting point synthetic fiber, for example, a vinylon binder fiber, an olefin binder fiber, a polyester binder fiber or the like can be suitably used.
As the low melting point synthetic fiber, a vinylon binder fiber is particularly preferable, and since the fiber dissolves in water at 70 ° C., the airgel and the fiber can be bonded to each other at the time of drying. A commercially available vinylon binder fiber can be used as appropriate, and for example, VPB105-1 manufactured by Kuraray Co., Ltd. can be applied.
The binder fiber may be a core-sheath fiber whose core is a high melting point component and whose sheath is a low melting point component.

By using at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer and / or a low-melting synthetic fiber as a binder, by containing the binder, in a papermaking process, etc. It is difficult for the airgel particle shape to collapse and it is easy to maintain its heat insulating properties. In particular, when the main fiber contains pulp and the airgel is porous silica particles, more specifically methyl silicate particles, the pulp is usually anionic in the pulp slurry containing water and pulp, and The porous silica particles added to the slurry, particularly methyl silicate particles, are anionic or amphoteric. Anionic pulp and anionic or amphoteric porous silica particles are unlikely to aggregate with each other and the yield tends to be low. Here, by using a cationic polymer and / or an amphoteric polymer as a binder, it is possible to promote the aggregation of pulp and porous silica particles and to increase the yield.
The yield can be further increased by using a known flocculant containing chitin, chitosan and the like.

The binder is preferably blended in an amount of 0.3 to 125 parts by weight with respect to 100 parts by weight of the main fiber. When the blending amount of the binder is less than 0.3 parts by weight, the particle shape of the airgel is not easily collapsed in the paper making process and the heat insulation is easily maintained. Moreover, when the compounding quantity of a binder exceeds 125 weight part, there exists a possibility that the intensity | strength of a heat insulating material may fall and it may become difficult to obtain desired paper-like processability.
When the main fiber contains pulp and the binder contains at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, from the same viewpoint, the blending amount of the water-soluble polymer is It is preferable to set it as 0.3-33 weight part with respect to 100 weight part of fibers, and it is more preferable to set it as 0.3-18 weight part especially.

<Other ingredients>
In addition, although not particularly limited, for example, a paper strength additive such as vegetable gum, aqueous cellulose derivative, sodium silicate, etc., which is usually used as an additive for papermaking, rosin, carboxymethyl cellulose, alkyl ketene dimer, alkenyl A sizing agent such as succinic anhydride, a yield improver such as polyacrylamide and sodium silicate, a dye, a pigment, and the like can be added by internal addition or a size press, if necessary. In addition to the above, for example, as additives, a dispersant such as a water-soluble polyurethane resin (for example, manufactured by Yoshimura Yuka Co., Ltd., Texanol PE-10F, etc.), an antifoaming agent (for example, manufactured by Meisei Chemical Industries, Ltd.) , Formless P new, etc.) can be used.

<Properties of thermal insulation>
The properties of the heat insulating material comprising the above components can be a sheet shape having a thickness of 15 μm to 1.2 cm, a basis weight of 10 to 480 g / m ² , and a density of 0.5 to 1.5 g / cm ³ . These numerical values are within the same range as general paper, and it can be seen that the heat insulating agent of the present invention has the same appearance and texture as paper. The heat insulating material does not need to be only one layer of the papermaking sheet, and may have a multilayer structure in which a plurality of sheets are bonded with an adhesive or the like, and a resin layer such as polyethylene is provided on one or both sides of the sheet. A laminate structure may be used. In particular, by adopting a laminate structure, it is possible to prevent the aerogel from falling off the sheet, and it is possible to increase the strength and heat insulating properties of the entire heat insulating material.

<Method for manufacturing heat insulating material>
1. Preparation of Papermaking Slurry 100 parts by weight of the main fiber, 35 to 210 parts by weight of the above-mentioned aerogel, and 0.3 to 125 parts by weight of the above binder are added to and mixed with water to prepare a mixed slurry. A mixed slurry) is prepared.
In addition, when using what contains said water-soluble polymer as a binder, a water-soluble polymer and an airgel are added and mixed with the slurry which suspended at least the main fiber in water, and a papermaking slurry is adjusted. It is preferable. Specifically, for example, when pulp is used as the main fiber and porous silica particles are used as the airgel, and the binder contains a water-soluble polymer, the slurry in which the pulp is suspended in water, the porous silica particles, It is preferable to prepare a papermaking slurry (mixed slurry) by adding and mixing a binder.

  In preparing the papermaking slurry, it is preferable to adjust by adding acid, alkali or the like, if necessary, so that the slurry has a pH of 7-8. In particular, when the airgel is a hydrophobized methyl silicate or the like, the chemical structure is most likely to be stable under conditions of pH 7-8. Therefore, it is desirable to prepare a slurry under the above conditions in order to maintain the porous structure of the particles.

2. Papermaking process The papermaking slurry is made using a known papermaking machine usually used in paper production. The slit width, drum diameter, drum rotation speed, press pressure, dryer temperature and the like of the paper machine can be appropriately changed depending on the desired properties of the heat insulating material sheet.

3. Attached process About the papermaking sheet obtained by the above papermaking process, if necessary, a plurality of sheets may be laminated via an adhesive, and a lamination process is performed by providing a resin layer such as polyethylene on one or both sides. May be.

<Thermal insulation method using thermal insulation>
About the heat insulating material of this invention, it is possible to show the heat insulation effect with respect to the target goods by means, such as packaging the target goods and sticking to the target goods. Here, the material of the target article is not particularly limited, and any material such as paper, plastic, plate material, and metal can be used. Its purpose of use can also be used for food and pharmaceutical containers and packaging materials, building materials, and the like.

  As mentioned above, although embodiment of this invention was described, the heat insulating material of this invention is not limited to the said example, A change can be added suitably.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.
In order to confirm the effect of the heat insulating material of the present invention, the following two experiments were conducted.

[Experiment 1]
<Creation of insulation>
1. Example 1: Thermal insulation material 300 mL of water was put into a 500 mL beaker, and 200 g of commercially available kenaf pulp, a critically dry hydrophobic gel powder of methyl silicate (average particle size 5 μm, specific surface area 750 m ² / g, Aerogel Enova manufactured by Cabot) 100g, 0.8g of cationic starch (Nippon Food Chemical Co., Ltd. # 40T) was added and stirred using a handy mixer at 10,000rpm until the whole became uniform to prepare a pulp slurry. .
Then, the screen papermaking said pulp slurry (material: nylon) was used to papermaking manually, followed by drying at room temperature a wire mesh-like, thick 0.2 mm, the heat insulating material having a basis weight of 200 g / m ² (adiabatic Sheet) was obtained. In addition, the external appearance, the flexibility, etc. of the obtained heat insulation sheet were similar to commercially available drawing paper.

2. Examples 2 to 5: Insulating material Insulation sheets prepared by drying three, five, seven, and ten sheets before drying on a paper sheet made in the same manner as in Example 1 2, 3, 4, and 5.

3. Comparative Examples 1 to 5: Paper As a comparative control, a commercially available drawing paper having a thickness of 0.2 mm and a basis weight of 210 g / m ² was used. The one using only one drawing paper was Comparative Example 1, and the three, five, seven, and ten sheets were used as Comparative Examples 2, 3, 4, and 5, respectively.

<Evaluation of thermal insulation performance>
Insulating sheets of Examples 1 to 5 and Comparative Examples 1 to 5 so as to cover the outer peripheral surface of a commercially available paper cup (9 oz, caliber 77 mm × height 91 mm, material: virgin pulp (outside), polyethylene (inside)) Each piece of paper was wrapped around. At that time, heat insulation sheet and paper do not use adhesive etc., wrap so that it adheres closely to the paper cup and does not overlap, and tape the outer surface with cellophane tape of 1cm width x about 5cm only at the boundary line Stopped.
In each of the paper cups, 250 mL of hot water at 95 ° C. was added, and immediately after the addition, the surface temperature of the sheet outside after 10 seconds, 20 seconds, and 30 seconds was measured. Table 1 shows the measurement results of the surface temperature.

  As shown in Table 1, compared with plain paper (drawing paper) having the same thickness and basis weight, the heat insulating material (heat insulating sheet) of the present invention is less likely to pass the temperature of hot water inside the paper cup through the outer surface. It was found that the insulation performance was excellent.

[Experiment 2]
<Creation of insulation>
1. Example 6: Heat insulation material 700 mL of water was put into a 1 L handy mixer, and 3.5 g of a commercially available polyester fiber (PET fiber, TA04PN SD 0.1 dtex x 3 mm) manufactured by Teijin Ltd. was put there at a rotational speed of 10,000 rpm. Stir until is uniform. To this, 1.2 g of vinylon binder fiber (VPB105-1 x 3 mm manufactured by Kuraray Co., Ltd.) was added and stirred. To this slurry, 7.0 g of a critically dry hydrophobic gel powder of methyl silicate (average particle diameter 90 μm, specific surface area 750 m ² / g, Aerogel Enova manufactured by Cabot) was added and stirred in the same manner to prepare a papermaking slurry.
Next, paper is made in the same manner as in Example 1, and dried with a rotary dryer to obtain a heat insulating material (heat insulating sheet) having a thickness of 0.25 mm and a basis weight of 100 g / m ^2. Was used as Example 6 (the thickness of the heat insulating material of Example 6 was 0.5 mm). In addition, the external appearance, the flexibility, etc. of the obtained heat insulation sheet were similar to a commercially available nonwoven fabric.

2. Examples 7 to 9: Insulating materials The insulating materials produced by the same method as in Example 6 were used by superposing four, six and eight sheets, respectively, as Examples 7, 8 and 9 (Examples respectively) The thickness of the insulation material is 1.0 mm, 1.5 mm, and 2.0 mm).

3. Comparative Examples 6 to 9: Nonwoven fabric As a comparative control, a non-woven fabric of 0.25 mm (100 parts by weight of polyester fiber (TA04PN SD 0.1 dtex x 3 mm manufactured by Teijin Ltd.), vinylon binder fiber (VPB105-1 x 3 mm manufactured by Kuraray Co., Ltd.) 3 parts by weight) was used. A comparative example 6 was obtained by using only two non-woven fabrics, and comparative examples 7, 8, and 9 were obtained by superposing four sheets, six sheets, and eight sheets, respectively.

4). Example 10: Heat insulation material 700 mL of water was put into a 1 L handy mixer, and 3.5 g of commercially available polyester fiber (PET fiber, TA04PN SD 0.1 dtex x 3 mm) manufactured by Teijin Ltd. was put there at a rotation speed of 10,000 rpm. Was stirred until. To this, 1.2 g of polyester binder fiber (PET binder fiber, TK08PN SD 0.2 dtex x 3 mm, manufactured by Teijin Ltd.) was added and stirred. Further, 3.1 g of cationic starch (Nippon Food Chemical Co., Ltd. # 40T), 7.0 g of critical dry hydrophobic gel powder of methyl silicate (average particle size 90 μm, specific surface area 750 m ² / g, Cabot Aerogel Enova) In addition, stirring was similarly performed to prepare a papermaking slurry.
Next, paper is made in the same manner as in Example 1, and dried with a rotary dryer to obtain a heat insulating material (heat insulating sheet) having a thickness of 0.25 mm and a basis weight of 130 g / m ^2. Was used as Example 10 (the thickness of the heat insulating material of Example 10 was 0.5 mm). In addition, the external appearance, the flexibility, etc. of the obtained heat insulation sheet were similar to a commercially available nonwoven fabric.

5. Examples 11 to 13: Heat insulating materials Heat insulating materials manufactured by the same method as in Example 10 were used as four, six and eight layers, respectively, which were designated as Examples 11, 12, and 13 (Examples respectively) The thickness of the insulation material is 1.0 mm, 1.5 mm, and 2.0 mm).

6). Comparative Examples 10 to 13: Nonwoven fabric As a comparative control, 0.25 mm nonwoven fabric (polyester fiber (TA04PN SD 0.1 dtex x 3 mm manufactured by Teijin Ltd.) 100 parts by weight, polyester binder fiber (PET binder fiber, Teijin Ltd. TK08PN SD 0.2 dtex x 3 mm) 33 parts by weight and cationic starch (Nippon Food Chemical Co., Ltd. # 40T) 36 parts by weight) were used. A comparative example 10 was obtained by using only two non-woven fabrics, and comparative examples 11, 12, and 13 were used by superimposing four, six and eight sheets, respectively.

<Evaluation of thermal insulation performance>
On the stainless steel column (diameter: 47 mm, height: 57 mm) heated to about 100 ° C., the heat insulating sheets (40 mm × 40 mm) of Examples 6 to 13 and the nonwoven fabrics (40 mm × 40 mm) of Comparative Examples 6 to 13 were used. placed. The surface temperature of the upper surface side of the sheet and nonwoven fabric after 10 seconds, 20 seconds, 30 seconds, and 60 seconds (the side opposite to the side where the sheet and nonwoven fabric contact with the cylinder) was measured. Table 2 shows the measurement results of the surface temperature.

  As shown in Table 2, it has been found that the heat insulating material (heat insulating sheet) of the present invention is less likely to pass through the temperature of a stainless steel column and is superior in heat insulating performance as compared with an equivalent non-woven fabric.

Claims (9)

A heat insulating material comprising a main fiber, an airgel, at least one water-soluble polymer selected from the group consisting of a cationic polymer and an amphoteric polymer, and / or a binder containing a low-melting synthetic fiber,
The airgel has a density of less than 0.5 g / cm ³ and a thermal conductivity of 0.02 W / (m · K) or less, and 35 to 210 parts by weight of the airgel is mixed with 100 parts by weight of the main fiber. A heat insulating material characterized by that. The binder includes the water-soluble polymer,
The heat insulating material according to claim 1, wherein the water-soluble polymer is at least one of cationized starch and amphoteric starch. The binder includes the low melting point synthetic fiber,
The heat insulating material according to claim 1, wherein the low melting point synthetic fiber is a vinylon binder fiber.   The said airgel is a heat insulating material of any one of Claims 1-3 which is the porous silica particle which airgelated the methylsilicate monomer by normal pressure drying or critical drying. The heat insulating material according to any one of claims 1 to 4, wherein the airgel has an average particle diameter of 2 to 140 µm and a specific surface area of 400 m ² / g or more. The heat insulating material according to any one of claims 1 to 5, wherein the heat insulating material has a thickness of 15 µm to 1.2 cm, a basis weight of 10 to 480 g / m ² , and a density of 0.5 to 1.5 g / cm ³ . From the group consisting of 100 parts by weight of the main fiber, 35 to 210 parts by weight of airgel having a density of less than 0.5 g / cm ³ and a thermal conductivity of 0.02 W / (m · K) or less, and a cationic polymer and an amphoteric polymer. A mixed slurry is prepared by adding and mixing 0.3 to 125 parts by weight of a binder containing at least one water-soluble polymer and / or low-melting synthetic fiber selected into water,
A method for producing a heat insulating material, wherein the mixed slurry is paper-made.   The manufacturing method of the heat insulating material of Claim 7 which makes the said mixed slurry at the time of papermaking pH 7-8. The binder of the mixed slurry comprises the water-soluble polymer;
The method for producing a heat insulating material according to claim 7 or 8, wherein the water-soluble polymer and the airgel are added to and mixed with a slurry in which at least the main fiber is suspended in water to adjust the mixed slurry.