WO2018012402A1

WO2018012402A1 - Heat insulating material and method for producing same

Info

Publication number: WO2018012402A1
Application number: PCT/JP2017/024835
Authority: WO
Inventors: 嘉村　輝雄; 隆欣伊藤
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2016-07-11
Filing date: 2017-07-06
Publication date: 2018-01-18
Also published as: KR20190027854A; CN109477606A; JPWO2018012402A1; TW201821727A; JP7192497B2

Abstract

The present invention provides a heat insulating material which comprises: a core layer (A) having a fine hollow structure; a gas absorption layer (B), at least a part of which is positioned outside the core layer (A), and which is capable of absorbing a gas; and a gas blocking layer (C) which is positioned outside the gas absorption layer (B), and which is capable of blocking a gas.

Description

Insulating material and manufacturing method thereof

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

The heat insulating material is used for the purpose of enhancing the heat insulating performance, and a foamed material such as urethane foam is used as a heat insulating material for a refrigerator, a freezer, a building material or the like. In recent years, in order to further improve the heat insulation properties, a vacuum heat insulating material is used in which urethane foam or glass fiber having a continuous hollow structure is used as a core material, and these core materials are vacuum packaged with a gas barrier packaging material (for example, Patent Document 1, Patent Document 2). Moreover, a vacuum chamber is used to manufacture such a vacuum heat insulating material.

A vacuum insulation material that does not use a vacuum chamber is manufactured by mixing a gas absorbent with the foaming resin composition that is the core material and then removing it with the gas absorbent while foaming with carbon dioxide gas. A method of creating a situation and improving the heat insulation performance (see, for example, Patent Document 3) has been proposed.

Other than this, a gas absorbent is not mixed with the resin composition, but a gas absorbent in the form of a sachet is installed outside the foamed urethane having a continuous hollow structure to absorb carbon dioxide inside (for example, a patent Reference 4) has also been proposed.

Japanese Patent Laid-Open No. 7-234067 Japanese Patent Laid-Open No. 9-138058 Japanese Patent Laid-Open No. 1995-053769 JP 1999-334864 A

However, in order to exhibit high heat insulation performance in vacuum packaging, a high vacuum of 10 Pa or less is generally required, and even if the degree of vacuum is slightly deteriorated, the performance is drastically lowered. Further, in the manufacturing process, it is necessary to maintain a high vacuum state for a long time using a vacuum chamber, which causes a decrease in productivity.

Moreover, in the conventional method as described in Patent Document 3, it is difficult to adjust the balance between foaming and gas absorption, and addition of a gas absorbent to the core material increases the thermal conductivity. Therefore, it is difficult to achieve sufficient heat insulation. Moreover, in the method as described in Patent Document 4, since gas absorption is localized, it takes a long time to remove the gas, and there are problems such as a decrease in physical strength derived from the communicating hollow structure. is there.

An object of the present invention is to provide a heat insulating material having high heat insulating performance without using a vacuum chamber.

As a result of intensive studies on the above problems, the present inventors have determined that a core layer (A) having a fine hollow structure, a gas absorption layer (B) that is at least partially located outside the core layer (A) and can absorb gas. And the heat insulating material having a gas barrier layer (C) which is located outside the gas absorption layer (B) and can shut off the gas, it has been found that the above problem can be solved.
That is, the present invention is as follows.
[1]
A core layer (A) having a fine hollow structure;
A gas absorption layer (B) capable of absorbing gas, at least a part of which is positioned outside the core layer (A), and a gas barrier layer positioned outside the gas absorption layer (B) and capable of blocking gas A heat insulating material having (C).
[2]
The heat insulating material according to [1], wherein the core layer (A) has a porosity of 90 to 99%.
[3]
The heat insulating material according to [1] or [2], wherein an average hollow diameter of the fine hollow structure of the core layer (A) is in the range of 1 to 500 μm.
[4]
The heat insulating material according to any one of [1] to [3], wherein the pressure of the fine hollow structure of the core layer (A) is in the range of 10 to 10,000 Pa.
[5]
The heat insulating material according to any one of [1] to [4], wherein the thickness of the core layer (A) is in the range of 0.5 to 40 mm.
[6]
The heat insulating material according to any one of [1] to [5], wherein an independent hollow body ratio of the fine hollow structure of the core layer (A) is 50% or more.
[7]
The heat insulating material according to any one of [1] to [6], wherein the gas absorption layer (B) directly or indirectly covers 40% or more of the surface of the core layer (A).
[8]
The heat insulating material according to any one of [1] to [7], wherein the gas absorption layer (B) can absorb at least one selected from the group consisting of carbon dioxide, water vapor, and oxygen.
[9]
The method for producing a heat insulating material according to any one of [1] to [8], comprising the following steps.
(1) Step of obtaining a core layer (A) having a fine hollow structure by foaming a resin (2) A gas absorbing layer (at least part of which is located outside the core layer (A) and capable of absorbing gas) B) causing the gas in the core layer (A) to be absorbed [10]
In the process of obtaining the said core layer (A), the manufacturing method of the heat insulating material as described in [9] using an extrusion foaming method.

According to the present invention, it is possible to provide a heat insulating material having high heat insulating performance without using a vacuum chamber.

It is a schematic diagram which shows 1 form of the heat insulating material using the foam composite of this invention. It is a schematic diagram which shows another form of the heat insulating material using the foam composite of this invention.

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiment is an exemplification for explaining the present invention, and is not intended to limit the present invention to the following embodiment. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

[Insulation]
The heat insulating material of the present embodiment is a core layer (A) having a fine hollow structure (hereinafter, also simply referred to as “core layer (A)”), at least part of which is located outside the core layer (A), Gas absorbing layer (B) capable of absorbing gas (hereinafter also referred to simply as “gas absorbing layer (B)”), and gas blocking layer located outside the gas absorbing layer (B) and capable of blocking gas (C) (hereinafter also referred to simply as “gas barrier layer (C)”). Hereinafter, the core layer (A), the gas absorption layer (B), and the gas barrier layer (C) will be described in detail.

[Core layer (A)]
The core layer (A) is located in the central core of the heat insulating material as in the example shown in FIG. 1 in the present embodiment, and is a fine hollow portion represented by a fine bubble (hereinafter referred to as “fine hollow”). A layer having a structure. Since the core layer (A) has a fine hollow structure, the heat insulating performance of the heat insulating material in the present embodiment is greatly improved.

The fine hollow structure means a structure having an average diameter (hereinafter, also referred to as “average hollow diameter”) of the fine hollow structure in the present embodiment in a range of 500 μm or less.
The average hollow diameter is preferably 1 to 300 μm, more preferably 1 to 100 μm, and further preferably 1 to 50 μm. When the average hollow diameter is 500 μm or less, the thermal conductivity tends to decrease when the inside of the hollow body is depressurized, and a good heat insulating material tends to be easily obtained. On the other hand, when the average hollow diameter is 1 μm or more, the porosity tends to be difficult to decrease. In order to obtain a fine hollow structure having an average hollow diameter in the above range, for example, in the case of a foam, the resin properties such as the type and amount of gas and nucleating agent that contribute to foaming, the melt tension value of the base resin, etc. The temperature and pressure at the time of molding, the shape of the molding machine, etc. are optimized. The average hollow diameter of the fine hollow structure can be measured by the method described in Examples described later.

The porosity of the core layer (A) having a fine hollow structure is preferably 90.0 to 99.0%, more preferably 93.0 to 98.5%, and further preferably 95.0% to 98. 0.0%. Since the thermal conductivity of the base material portion is high, the thermal conductivity and strength tend to be within a preferable range by being in such a range. In order to obtain the core layer (A) having a porosity in the above range, for example, in the case of a foam, the amount of gas that contributes to foaming may be increased. The porosity of the core layer (A) can be measured by the method described in Examples described later.

Independent hollow body ratio of the fine hollow structure (in the present specification, the independent hollow body ratio is the ratio of the fine hollow structure not communicating with the outside of the core layer (A) among all the fine hollow structures in the core layer (A)). In order to express practical strength and heat insulation performance, it is preferably 50% or more, more preferably 70% or more, and further preferably 80% or more. The independent hollow body ratio of the fine hollow structure can be measured by the method described in Examples described later.

The core layer (A) having a fine hollow structure can improve the heat insulation performance by lowering the pressure in the hollow part. The pressure of the fine hollow structure is preferably 10 to 10,000 Pa, more preferably 15 to 5000 Pa, and still more preferably 20 to 1000 Pa. When the pressure is 10 Pa or more, the influence of gas leakage or the like is relatively reduced, and the pressure tends to be maintained. When the pressure is 10000 Pa or less, a good heat insulating material with low thermal conductivity is obtained. It is easy to be done. In order to obtain a fine hollow structure in which the pressure is in the above range, for example, a gas absorption layer (B) having a capability of absorbing a large amount of gas contained in the core layer (A) may be used. The pressure of the fine hollow structure can be measured by the method described in Examples described later.

The thickness of the core layer (A) having a fine hollow structure is preferably 0.5 to 40 mm, more preferably 1 to 25 mm, and further preferably 2 to 20 mm. When the thickness is 0.5 mm or more, heat insulation performance as a heat insulating material can be maintained, and when the thickness is 40 mm or less, gas absorption inside the core layer (A) by the gas absorption layer (B) is achieved. Tends to be easy and the heat insulation performance tends to be excellent.

The production method of the core layer (A) having a fine hollow structure is not particularly limited. For example, a foaming agent is included in the base material to create a fine hollow structure by foaming, or hollow microcapsules are dispersed in the base material. For example, a technique in which a fibrous material having a hollow structure is contained in the substrate can be used. Among these, considering the ease of production and gas permeability, a method of making the base material contain a foaming agent and creating a fine hollow structure by the extrusion foaming method or the bead foaming method is preferable, and the extrusion foaming method is more preferable.

The resin used as the substrate is not particularly limited. For example, polyurethane, polyvinyl chloride, polycarbonate, polystyrene, polytetrafluoroethylene, polyolefin, ionomer, polysulfone, cellulose acetate and its analogs, ethyl cellulose, polydimethylsiloxane, silicone resin, And chlorosulfonated polyethylene. From the viewpoint of gas permeability and strength, polyurethane, polyvinyl chloride, polycarbonate, polystyrene, polyolefin, cellulose acetate and its analogs, and silicone resin are preferable, and polystyrene and polyolefin are more preferable. One or more of these can be used in combination. Moreover, these can be obtained easily and can use them suitably.

The foaming agent is used to expand rubber, plastic, etc., which are base materials, in order to create a fine hollow structure, and is roughly classified into a chemical foaming agent and a physical foaming agent.

A chemical foaming agent is a substance that generates a gas such as nitrogen, ammonia gas, hydrogen, carbon dioxide, water vapor, or oxygen by thermal decomposition or chemical reaction.
Examples of chemical blowing agents include azo, nitroso, hydrazide, semicarbazide, azide, triazole, tetrazole, isocyanate, bicarbonate, carbonate, nitrite, hydride, sodium bicarbonate and acid. Examples include a combination, a combination of hydrogen peroxide and yeast, and a combination of metal powder and acid. Carbonate that generates carbon dioxide and bicarbonate are preferable because they can generate high-purity gas. One or more of these can be used in combination. Moreover, these can be obtained easily and can be used suitably.

Physical foaming agent is a substance that foams due to physical changes such as pressure release and vaporization of compressed gas. Specific examples include inert gases such as nitrogen, aliphatic hydrocarbons, halogenated aliphatic hydrocarbons, water, and carbon dioxide. Carbon dioxide and water are preferred from the viewpoints of safety, environmental compatibility, and gas absorption. One or more of these can be used in combination. Moreover, these can be obtained easily and can be used suitably.

The amount of foaming agent added cannot be uniquely determined because the optimum amount varies depending on the type of base material and the type of foaming agent.

A method for producing a fine hollow structure using a foaming agent is performed by foaming in a base material containing a foaming agent, and the foaming method is variously determined depending on the type and amount of the foaming agent. As an example, when carbon dioxide gas is used as the physical foaming agent, it can be suitably carried out according to a technique described in JP 2010-173263A as a known technique.

[Gas absorption layer (B)]
The gas absorption layer (B) is located outside the core layer (A) of the heat insulating material as in the example shown in FIG. 1 in this embodiment, and the core layer (A It is a layer that can absorb the gas inside. In the example shown in FIG. 1, the gas absorption layer (B) completely includes the core layer (A), but the gas absorption layer (B) may be located outside the core layer (A). As in another example shown in FIG. 2, the gas absorption layer (B) may not include a part of the core layer (A) and may include a part other than the end of the core layer (A). . Since the gas absorption layer (B) absorbs the gas, the pressure in the hollow portion of the core layer (A) is lowered, so that the heat insulation performance is improved.

The gas absorption layer (B) is a layer capable of absorbing gas by containing a gas absorbent, for example. Specific examples of the mode of containing the gas absorbent include a layer using the gas absorbent alone or a layer containing the gas absorbent in the base material. As the base material, in addition to the same base material used for the core layer (A), rubbers such as natural rubber, butadiene rubber, silicone rubber, vinyl acetate emulsion adhesive, rubber adhesive, starch adhesive Such adhesives and pressure-sensitive adhesives can be suitably used.

The gas absorbent is a substance that can absorb gas, and the type of gas to be absorbed is not particularly limited, and examples thereof include carbon dioxide, water vapor, and oxygen.
Examples of gas absorbents include alkali metal hydroxides, alkaline earth metal hydroxides, amine compounds, epoxy compounds, alkali metals, alkaline earth metals, alkali metal hydrides, alkaline earth metal hydrides, Lithium aluminum hydride, metal sulfate, calcium chloride, activated alumina, silica gel, molecular sieve, alkali metal carbonate, calcium oxide, sulfuric acid, phosphorus oxide, iron, sulfite, ascorbic acid, glycerin, MXD6 nylon, ethylenic acid Saturated hydrocarbons, polymers with cyclohexene groups, oxygen atom defect structures of metal oxides such as titanium and cerium, alkali metal hydroxides, alkaline earth metal hydroxides, metal sulfates, chlorides Calcium, activated alumina, silica gel, molecular sieve, alkali Metal carbonates, calcium oxide, iron, and preferable because sulfites hardly generate inert gas during inexpensive gas absorption. One or more of these can be used in combination. Moreover, these can be obtained easily and can be used suitably.

When a layer containing a gas absorbent in a base is used as the gas absorption layer (B), the amount of the gas absorbent added is preferably in the range of 5 to 99 parts by weight with respect to 100 parts by weight of the base. More preferably, the amount is 10 to 99 parts by mass in order to increase the amount of absorption and the rate of absorption.
The gas absorption layer (B) may have a multilayer structure or a single layer structure, and a layer other than the gas absorption layer may be provided between the gas absorption layer (B) and the core layer (A).
Examples of layers other than gas absorption include an adhesive layer that bonds the core layer (A) and the gas absorption layer (B), and a buffer layer that prevents components of the gas absorption layer from moving to the core layer (A). It is done.

In order to increase the rate at which the gas absorption layer (B) absorbs and removes the gas inside the core layer (A), the gas absorption layer (B) directly or indirectly covers 40% or more of the surface area of the core layer (A). Preferably, it covers 75% or more, and more preferably covers 80% or more.

The thickness of the gas absorption layer (B) is preferably 10 to 500 μm. By being in this range, the gas absorption performance and the heat insulation performance tend to be compatible. When the thickness is 10 μm or more, the performance of the gas absorbent that contributes is easily obtained, and when the thickness is 500 μm or less, the ratio of the gas absorption layer (B) in the heat insulating material does not become too large, and the thermal conductivity. It tends to be able to suppress the deterioration of.
The gas absorption layer (B) can be produced, for example, by melting and kneading a gas absorbent in a resin to produce resin pellets and film-molding. As another form, it can also be produced by coating the core layer (A) or film after kneading a gas absorbent with the above-mentioned adhesive.

[Gas barrier layer (C)]
The gas blocking layer (C) is a layer that is located outside the gas absorption layer (B) and can block gas from the outside, as in the example shown in FIG. 1 in the present embodiment.
The gas barrier layer (C) is not particularly limited as long as it can prevent air from entering the core layer (A). However, a metal oxide vapor deposition film, a silicon oxide vapor deposition film, and a metal vapor deposition film are used. A multilayer body having one or more selected from the group consisting of metal thin films is preferable because of its excellent gas barrier properties. These are available as commercial products and can be suitably used. One or more of these can be used in combination.
The gas barrier layer (C) may have a multilayer structure or a single layer structure, and a layer other than a gas barrier layer between the gas barrier layer (C) and the gas absorption layer (B) or the atmosphere. These layers may be provided.
Examples of layers other than the gas blocking layer include a sealant resin layer for performing heat sealing and a protective layer for preventing pinholes in the gas blocking layer (C).

The thickness of the gas barrier layer (C) is preferably 1 μm to 500 μm. By being in this range, the gas barrier performance and the heat insulating performance tend to be compatible.

[Production method of heat insulating material]
Although the manufacturing method of the heat insulating material of this embodiment will not be specifically limited if the heat insulating material of this embodiment can be obtained, For example, it has the following process.
(1) A step of obtaining a core layer (A) having a fine hollow structure by foaming a resin (2) A step of absorbing a gas inside the core layer (A) in a gas absorption layer (B) capable of absorbing gas

The step (1) for obtaining the core layer is not particularly limited, and examples thereof include those similar to the above-described “method for producing the core layer (A)”. Further, the step (2) for absorbing gas is not particularly limited. For example, the core layer (A) having a fine hollow structure is combined with the gas absorption layer (B) and the gas blocking layer (C). It can be carried out. For example, the gas absorption layer (B) and the gas barrier layer (C) are bonded by a conventional dry laminate, and the gas absorption layer (B) and the gas barrier layer (C) are combined. Examples thereof include a technique of applying an adhesive to the layer and bonding it to the core layer (A). As another form, the core layer (A) and the gas absorption layer (B) are bonded with a conventional dry laminate or heat laminate, and the composite of the core layer (A) and the gas absorption layer (B) is formed. A technique of covering without adhering with the gas barrier layer (C) may also be mentioned. Moreover, when using a heat insulating material, it is preferable to seal a terminal part, for example, by heat-sealing and sealing, heat insulation and performance can be stabilized for a long term.

In the step (1) of obtaining the core layer, it is preferable to use the extrusion foaming method among the “method for producing the core layer (A)” described above.

Hereinafter, the present embodiment will be specifically described by way of examples, but the present embodiment is not limited thereto.

[Average hollow diameter of fine hollow structure]
The average hollow diameter of the fine hollow structure was calculated by the following method. Specifically, first, the core layer (A) is cut along an arbitrary X direction orthogonal to the thickness direction and the Y direction orthogonal to the thickness direction and the X direction, and the center portion of each cut surface is cut. The image was magnified 20 to 100 times with a scanning electron microscope (trade name “JSM-6460LA” manufactured by JEOL Ltd.).
Next, the photographed image was printed on A4 paper, and a straight line having a length of 60 mm was drawn on the image. Here, the cut surface cut in the X direction was drawn in parallel with the X direction, and the cut surface cut in the Y direction was drawn in parallel with the Y direction. The hollow average chord length (t) is calculated from the number of hollows existing on each straight line (including point contact) by the following formula, and the average chord length in the X direction (tX direction) and the average chord length in the Y direction ( tY direction).
Average chord length (t) = 60 (mm) / (number of hollows × photo magnification)
Furthermore, in both the enlarged photograph of the cut surface cut along the X direction and the enlarged photograph of the cut surface cut along the direction orthogonal to the Y direction, the Z direction (thickness direction) orthogonal to the X direction and the Y direction. Draw a straight line with a length of 60 mm parallel to each other, count the number of hollows on these straight lines, calculate the average chord length (t) in the thickness direction for each cut surface, and calculate the average chord length The arithmetic average value of (t) was calculated, and this arithmetic average value was defined as the average chord length in the thickness direction (tZ direction).
And based on the calculated average chord length (t) in each direction, the average hollow diameter of the fine hollow structure was calculated by the following formula.
Average hollow diameter (mm) = (tX direction + tY direction + tZ direction) / 3

[Porosity]
From the density of the base material serving as the base of the core layer (A) and the density of the core layer (A), the porosity of the core layer (A) was determined by the following calculation formula.
Porosity (%) = (base material density−core layer (A) density) / (base material density) × 100

[Independent hollow body ratio of fine hollow structure]
After cutting out the test piece of the heat insulating material so that the core layer (A) has a rectangular parallelepiped shape with a length of 25 mm, a width of 25 mm, and a thickness of 20 mm (if the thickness is insufficient, the cut test pieces are stacked to form the above rectangular solid The test piece was allowed to stand for one day in a thermostatic chamber under conditions of atmospheric pressure, relative humidity 50%, and temperature 23 ° C.
Next, the exact apparent volume value Va of this test piece was measured. Next, after sufficiently drying the test piece, the volume value Vx was measured with an air comparison type hydrometer 930 manufactured by Toshiba Beckman Co., Ltd. according to the procedure C described in ASTM-D2856-70. And based on these volume value Va and volume value Vx, the independent hollow body rate of the fine hollow structure was computed from the following formula. In addition, each measurement and each calculation were performed about five different test pieces, and the average value was calculated | required. This average value was defined as the independent hollow body ratio.
Independent hollow body ratio (%) = (Vx−W / ρ) × 100 / (Va−W / ρ)
Vx: Sum of the volume of the resin constituting the fine hollow structure and the total hollow volume of the independent hollow portion in the foamed resin molded body (cm ³ )
Va: Apparent volume calculated geometrically (cm ³ )
W: Mass of the foamed resin molding (g)
ρ: density of the base material constituting the core layer (A) (g / cm ³ )

[Pressure of fine hollow structure]
<Method 1>
An absolute pressure sensor (Optex FA: FHAV-050KP) welded to an injection needle with an inner diameter of 1.2 mm was prepared. Subsequently, the injection needle with an absolute pressure sensor and the produced heat insulating material were put in a glove box, and the inside of the glove box was replaced with carbon dioxide. After that, the tip of the injection needle with an absolute pressure sensor was pierced so as to reach the central portion of the core layer (A) of the heat insulating material produced, and the epoxy adhesive (Nichiban: Araldite AR-R30) was pointed to the injection needle. Was applied to prevent gas from entering from the outside. After 7 days, the pressure of the fine hollow structure was measured. The injection needle was pierced within one hour after the heat insulating material was produced. In addition, in the heat insulating material which measured the pressure, since the heat conductivity mentioned later cannot be measured after that, the heat conductivity produced and measured another heat insulating material of the same structure.
<Method 2>
The heat insulating material in which the gas barrier layer (C) is not integrated with the core layer (A) with an adhesive or the like was measured by the following method which can be measured more easily.
An acrylic vacuum chamber was prepared, and a high-precision vacuum gauge (Canon Anelva Co., Ltd .: M-342DG) was attached thereto. Subsequently, after the insulation material that has been passed for two weeks has been placed in the chamber, a displacement sensor (Omron: ZX2) that can accurately measure the distance is placed outside the chamber, and the displacement sensor and chamber are placed in the chamber. Measured the distance to the surface of the insulation. After that, if the inside of the chamber is slowly evacuated, the gas blocking layer (C) moves when the pressure inside the chamber becomes lower than the pressure of the core layer (A). By detecting this movement with the displacement sensor, The pressure of the core layer (A) was measured.

[thickness]
The thickness of the core layer (A) was measured in units of 0.1 millimeter using a caliper.
The thicknesses of the gas absorption layer (B) and the gas barrier layer (C) were measured in units of 1 micrometer by observing a cross-sectional portion of each layer with a scanning electron microscope (JSM-6460LA, manufactured by JEOL Ltd.).
The thickness of the test sample of the heat insulator was measured simultaneously by the thermal conductivity measurement with the HFM436.

[Thermal conductivity]
In accordance with the HFM method described in JIS A1412, the thermal conductivity of the heat insulating material was measured at 25 degrees using a thermal conductivity measuring device HFM436 manufactured by Netch Japan Co., Ltd.
Thermal conductivity is
A rating of 0.020 W / mK or less,
B evaluation of 0.021 to 0.025 W / mK
C evaluation of 0.026 to 0.030 W / mK
What was 0.031 W / mK or more was made into D evaluation.
What was evaluated as D is rejected.

[Example 1]
<Production of Gas Absorbing Layer (B1) and Compounding with Gas Barrier Layer (C)>
The gas absorption layer (B1) was prepared using a polyethylene resin (ELITE 5220G manufactured by Dow Chemical Company) as a base material, calcium hydroxide as a carbon dioxide absorbent, and calcium oxide as a water vapor absorbent.
First, melt-kneading was carried out at a ratio of polyethylene resin / calcium hydroxide = 51 parts by mass / 49 parts by mass to prepare resin pellets (b1-1) for forming a gas absorption layer (B). Similarly, melt-kneading was performed at a ratio of polyethylene resin / calcium oxide = 60 parts by mass / 40 parts by mass to prepare resin pellets (b1-2) for forming the gas absorption layer (B).
Subsequently, a two-layer film was formed using the resin pellets (b1-1) and (b1-2) at a ratio of 1: 1 to obtain a gas absorption layer (B1) having a thickness of 100 μm.
Subsequent to the (b1-1) layer side of the gas absorption layer (B1) produced, a dry laminate adhesive TM250HV manufactured by Toyo Morton and a curing agent CAT-RT86L-60 were diluted twice with ethyl acetate. After coating with a bar coater and drying, a commercially available gas barrier film having a layer structure of PET / DL / Al / LDPE / LLDPE as a gas barrier layer (C) (San-A Kaken: for retort pouches, PET: polyethylene terephthalate, The LLDPE side of DL: adhesive, Al: aluminum foil, LDPE: low density polyethylene, LLDPE: linear short chain branched polyethylene) is bonded and compounded by dry lamination, and the gas absorption layer (B1) and gas barrier layer ( C) was obtained.

<Preparation of core layer (A1) and composite with multilayer film>
A tandem type extruder in which a first extruder and a second extruder are connected was prepared. 100 parts by mass of polystyrene resin (G9305 manufactured by PS Japan Co., Ltd.) is supplied to the first extruder of the tandem extruder and melt kneaded, and carbon dioxide as a foaming agent from the middle of the flow path of the first extruder. The melted polystyrene resin and carbon dioxide were uniformly mixed and kneaded, and the polystyrene resin was continuously supplied to the second extruder and cooled to a temperature suitable for foaming while being melt-kneaded. Then, polystyrene resin is extruded and foamed from a circular mold attached to the tip of the second extruder, and the resulting cylindrical foamed product is cooled along with the mandrel, and is cylindrical by a cutter at one point on the mandrel. The foam molded body was cut into a 5 mm thick core layer (A1) having a fine hollow structure. Table 1 shows the average hollow diameter, porosity, and independent hollow body ratio of the core layer (A1).
Subsequently, the gas barrier layer (C) is formed on the (b1-2) layer side of the gas absorption layer (B1) of the multilayer film having the gas absorption layer (B1) and the gas barrier layer (C) produced by the above method. The core layer (A) was bonded using an adhesive in the same manner as the bonded method. And the terminal part was sealed in the range of 20 mm in width using the heat seal (made by Fuji Impulse). Seven days later, the thermal conductivity and pressure (method 1) of the composite (heat insulating material) of this core layer (A1) -gas absorption layer (B1) -gas barrier layer (C) were measured. The results are shown in Table 1.

[Example 2]
<Production of gas absorption layer (B2)>
The gas absorption layer (B2) was prepared using polyethylene resin (ELITE 5220G manufactured by Dow Chemical Co., Ltd.) as a base material, calcium hydroxide as a carbon dioxide absorbent, and calcium oxide as a water vapor absorbent.
First, melt-kneading was carried out at a ratio of polyethylene resin / calcium hydroxide = 50 parts by mass / 50 parts by mass to prepare resin pellets (b2-1) for forming the gas absorption layer (B). Similarly, melt-kneading was carried out at a ratio of polyethylene resin / calcium oxide = 50 parts by mass / 50 parts by mass to prepare resin pellets (b2-2) for forming the gas absorption layer (B).
Subsequently, a two-layer film was formed using the resin pellets (b2-1) and (b2-2) at a ratio of 1.4 to 1, and a gas absorption layer (B2) having a thickness of 120 μm was obtained.

<Composition of production of core layer (A2) and gas absorption layer (B2)>
A core layer (A) was produced in the same manner as in Example 1 except that carbon dioxide and water were used as the foaming agent. Table 1 shows the average hollow diameter, porosity, and independent hollow body ratio of the produced core layer (A2).
Subsequently, the (b2-1) layer side of the gas absorption layer (B2) was bonded to the core layer (A2) produced by the above method to produce a composite. This step was performed in a carbon dioxide atmosphere.

<Composite of core layer (A2) gas absorption layer (B2) composite and gas barrier layer (C)>
The composite of the core layer (A2) and the gas absorption layer (B2) produced above is completely covered with the gas barrier layer (C) described in Example 1, and between the composite and the gas barrier layer (C). After removing the gas as much as possible, the end portion was sealed in a range of 10 mm in width using a heat seal. This step was performed in a carbon dioxide atmosphere. Two weeks later, the thermal conductivity and pressure (Method 2) of the composite (heat insulating material) of this core layer (A2) -gas absorption layer (B2) -gas barrier layer (C) were measured. The results are shown in Table 1.

[Example 3]
As the core layer (A), a composite (heat insulating material) was prepared in the same manner as in Example 2 except that the core layer (A3) having the average hollow diameter, porosity, and independent hollow body ratio shown in Table 1 was used. The thermal conductivity and pressure (Method 2) were measured. The results are shown in Table 1.

[Example 4]
A core layer (A2) was obtained in the same manner as in Example 2. Subsequently, 1/3 of the surface of the core layer (A2) was bonded to the gas absorption layer (B2), and the whole was covered with the gas barrier layer (C). After removing the gas between the gas barrier layers (C) as much as possible, the end portion was sealed with a heat seal in the range of a width of 10 mm. This step was performed in a carbon dioxide atmosphere. Two weeks later, the thermal conductivity and pressure (Method 2) of the composite (heat insulating material) of this core layer (A2) -gas absorption layer (B2) -gas barrier layer (C) were measured. The results are shown in Table 1.

[Comparative Example 1]
The thermal conductivity was measured using a cell board manufactured by Iwakura Chemical Industry Co., Ltd., which is a conventional polystyrene foam, as a heat insulating material, but the results were inferior to those of the examples (Table 1). The results of other measurements and evaluations are shown in Table 1.

[Comparative Example 2]
Although the gas absorption layer (B1) and the gas barrier layer (C) were not used, only the core layer (A1) obtained by the same method as in Example 1 was produced, and the thermal conductivity was measured using it as a heat insulating material. Since the pressure of the fine hollow body did not decrease, the thermal conductivity was inferior to the examples (Table 1). The results of other measurements and evaluations are shown in Table 1.

[Comparative Example 3]
Although the gas absorption layer (B2) and the gas barrier layer (C) were not used, only the core layer (A2) obtained by the same method as in Example 2 was produced, and the thermal conductivity was measured using it as a heat insulating material. Since the pressure of the fine hollow body did not decrease, the thermal conductivity was inferior to the examples (Table 1). The results of other measurements and evaluations are shown in Table 1.

[Reference Example 1]
The powder of calcium hydroxide and calcium oxide used when producing the pellet for the gas absorption layer of Example 1 was put into a gas-permeable pouch to produce a gas absorption pouch. Subsequently, after obtaining the core layer (A1) by the same method as in Example 1, a gas absorption sachet was placed on the core layer (A1). Cover the entire core layer (A1) and gas absorption pouch with the gas barrier layer (C), remove the gas between the gas barrier layer (C) as much as possible, and then heat-seal the end part within a width of 10mm. And sealed. This step was performed in a carbon dioxide atmosphere. Two weeks later, the pressure (method 2) and thermal conductivity of the composite were measured. However, since the bag-shaped gas absorption sachet was used instead of the gas absorption layer (B), the pressure drop was small. Moreover, since the sachet portion protruded from the surface of the heat insulating material, the heat conductivity could not be measured accurately.

This application is based on a Japanese patent application (Japanese Patent Application No. 2016-136563) filed with the Japan Patent Office on July 11, 2016, the contents of which are incorporated herein by reference.

Claims

A core layer (A) having a fine hollow structure;
A gas absorption layer (B) capable of absorbing gas, at least a part of which is positioned outside the core layer (A), and a gas barrier layer positioned outside the gas absorption layer (B) and capable of blocking gas A heat insulating material having (C).
The heat insulating material according to claim 1, wherein the porosity of the core layer (A) is in the range of 90 to 99%.
The heat insulating material according to claim 1 or 2, wherein an average hollow diameter of the fine hollow structure of the core layer (A) is in the range of 1 to 500 µm.
The heat insulating material according to any one of claims 1 to 3, wherein the pressure of the fine hollow structure of the core layer (A) is in the range of 10 to 10,000 Pa.
The heat insulating material according to any one of claims 1 to 4, wherein the thickness of the core layer (A) is in the range of 0.5 to 40 mm.
The heat insulating material according to any one of claims 1 to 5, wherein an independent hollow body ratio of the fine hollow structure of the core layer (A) is 50% or more.
The heat insulating material according to any one of claims 1 to 6, wherein the gas absorption layer (B) directly or indirectly covers 40% or more of the surface of the core layer (A).
The heat insulating material according to any one of claims 1 to 7, wherein the gas absorption layer (B) can absorb one or more selected from the group consisting of carbon dioxide, water vapor, and oxygen.
The method for producing a heat insulating material according to any one of claims 1 to 8, comprising the following steps.
(1) Step of obtaining a core layer (A) having a fine hollow structure by foaming a resin (2) A gas absorbing layer (at least part of which is located outside the core layer (A) and capable of absorbing gas) B) causing the gas inside the core layer (A) to be absorbed
The method for manufacturing a heat insulating material according to claim 9, wherein an extrusion foaming method is used in the step of obtaining the core layer (A).