JP7368327B2 - Airgel molded product and its manufacturing method - Google Patents

Description

The present invention relates to an airgel molded article and a method for manufacturing the same.

Insulating materials molded into a container shape are used to keep food, medical care, pharmaceuticals, etc. cold or hot. For example, there are things that are pre-formed into the shape that will be used, such as styrofoam and vacuum insulation, cold-warm boxes, cold-warm appliances such as freezers/refrigerators, and things that have insulation pasted on the inner box of a container.

Examples of raw materials for such heat insulating materials include vacuum heat insulating materials, hard urethane foams, and polystyrene foams (see Patent Documents 1 and 2). Furthermore, in recent years, materials in which airgel, which is a material with excellent heat insulation performance, is combined with nonwoven fabric have also been used (see Patent Document 3).

Japanese Patent Application Publication No. 2004-212042 Patent-6192634 Special table 2015-536849

However, although vacuum insulation materials, hard urethane foams, and the like have excellent heat insulation performance, they have poor moldability, so it is difficult to mold them into a container shape in post-processing. For example, a plurality of base materials are bonded together and processed into a container shape, but gaps tend to occur during bonding, making it difficult to obtain excellent heat insulation performance. Although polystyrene foam has excellent moldability, its insulation performance is inferior to vacuum insulation materials and rigid urethane foam. Furthermore, these materials have the problem that their insulation properties deteriorate over time.

In addition, in composite materials of airgel and nonwoven fabric, the airgel particles easily fall off from the nonwoven fabric (powder falling off), which can easily contaminate molds and equipment during molding. Hard to get.

Therefore, the present invention provides an airgel molded product and an airgel molded product that have less powder falling, excellent molding processability (for example, it is possible to form curved surfaces and corners), and even better heat insulation performance. Our goal is to provide a method for manufacturing products.

The present inventors conducted extensive research and found that the above problems could be solved by using a specific airgel composite material, and completed the present invention. That is, the present invention is as follows.

The present invention
An airgel molded article obtained by thermoforming an airgel composite material in which airgel is filled inside an open cell resin foam,
The open cell resin foam contains a thermoplastic resin,
The weight loss rate of the airgel at 300°C measured in accordance with JIS K-7120 is less than 15%,
The airgel composite material has a 25% compressive load of 10 to 1000 kPa as measured in accordance with JIS K-6254.

The open cell resin foam is a skinned open cell resin foam having a foam layer having open cells and a skin layer formed on two opposing surfaces of the foam layer,
The skin layer includes open cells that reach the surface of the skin layer,
The average cell diameter RA of open cells in the surface of the skin layer observed from the normal direction of the surface of the skin layer, and the average cell diameter RB of the open cells in the foam layer in a cross section perpendicular to the surface of the skin layer. The ratio (RA/RB) may be 1/1000 to 1/2.
The open-cell resin foam has an air permeability of 0.01 cm ³ /cm ² /sec. It may be more than that.
The open-cell resin foam is made of polyolefin resin, polystyrene resin, polyester resin, polyether resin, acrylic resin, polyamide resin, vinyl chloride resin, polycarbonate resin, fluorine resin, and a polyolefin resin whose softening temperature is 200° C. or lower. It may contain at least one type of resin.

Further, the present invention is a heat insulating appliance containing the airgel molded article.

Further, the present invention is a refrigerator-freezer having a heat retaining member and/or a cold retaining member containing the arogel molded product.

Further, the present invention is a cold/warm container having a heat insulating member and/or a cold insulating member containing the airgel molded article.

Moreover, the present invention
The method for producing the airgel molded article,
This is a method for producing an airgel molded article, which includes a step of thermoforming the airgel composite material.

The thermoforming may be vacuum forming.
The airgel composite material may be thermoformed without bonding any member other than the airgel composite material.

Moreover, the present invention
An airgel composite material in which airgel is filled inside an open cell resin foam,
The open cell resin foam contains a thermoplastic resin,
The airgel has a weight loss rate of less than 15% at 300°C measured in accordance with JIS K-7120,
The airgel composite material has a 25% compressive load of 10 to 1000 kPa as measured in accordance with JIS K-6254,
It is an airgel composite material used for thermoforming.

According to the present invention, it is possible to provide an airgel molded article and a method for producing an airgel molded article, which have less powder falling, excellent molding processability, and further excellent heat insulation performance.

It is a cross-sectional photograph of an open cell resin foam with a skin. It is a photograph taken from the normal direction of the surface of the skin layer of the open-cell resin foam with skin.

Hereinafter, the airgel molded article and the manufacturing method thereof according to the present invention will be described in detail.

In the present invention, normal pressure refers to a pressure that is neither reduced nor increased. Further, "under reduced pressure" refers to a state where the pressure is artificially reduced below atmospheric pressure.

In the present invention, the density is an apparent density measured in accordance with JIS K7222:2005 "Foamed plastics and rubber - How to determine apparent density".

In the present invention, the airgel composite material is an open-cell resin foam filled with airgel, and the open-cell resin foam before being filled with airgel and the open-cell resin foam after being filled with airgel. may be treated as the same thing, and the explanation of one may be omitted or replaced with the explanation of the other.

In the following, foam, resin foam, etc. may be used interchangeably.

Powder shedding usually means that airgel powder is detached from an airgel composite material during the manufacturing process of an airgel molded article, but it may also mean that airgel powder is detached from the airgel molded article itself. .

<<<<<<Airgel molded product>>>>>>
The airgel molded article is an airgel composite thermoformed article obtained by thermoforming an airgel composite material. Here, the airgel composite material includes an open-cell resin foam and an airgel filled inside the open-cell resin foam. Therefore, an airgel composite thermoformed product obtained by thermoforming this airgel composite usually has a structure including a cell structure made of resin and an airgel filled inside the cell.

The airgel molded article may be composed only of the airgel composite thermoformed article, or may include other members.

The shape of the airgel molded article can be made into an appropriate shape depending on the use.

<<<<Airgel composite material>>>>
The airgel composite material constituting the airgel molded article will be explained. The airgel composite includes an open cell resin foam and an airgel filled inside the open cell resin foam.

The average filling rate of the airgel that occupies the individual cells (cells) contained in the foam (the proportion of the volume that the filled airgel occupies within the cells) is not particularly limited, but can be 50% to 100%. , more preferably 70% to 100%, more preferably 90% to 100%. When the average filling rate of the airgel is within this range, the airgel composite material and the airgel molded article have excellent heat insulation properties.

The thickness of the airgel composite material (or foam) may be 0.05 mm or more, 0.10 mm or more, 0.20 mm or more, 0.50 mm or more, 0.75 mm or more, 1.00 mm or more, and 40. It may be 0 mm or less, 30.0 mm or less, 20.0 mm or less, 10.0 mm or less, 5.00 mm or less, 4.00 mm or less, 3.00 mm or less, or 2.00 mm or less.

<<<Aerogel>>>
The airgel is not particularly limited as long as it is a low density dry gel. It includes not only aerogels obtained using supercritical fluid drying, but also xerogels obtained by normal drying processes, cryogels obtained by freeze-drying, etc.

<<Ingredients of airgel>>
Any suitable airgel component can be used as the airgel. For example, one can choose from inorganic aerogels such as silica aerogels and alumina aerogels, organic aerogels such as resorcinol-formaldehyde aerogels (RF aerogels), cellulose nanofiber aerogels (CNF aerogels), carbon aerogels, and mixtures thereof. can. As the airgel, silica airgel containing silica (SiO ₂ ) can be suitably used.

Airgel is usually produced by filling an open-cell resin foam with a sol solution, which is a precursor of airgel, and then gelling and drying within the foam to form an airgel.

<<Physical properties/properties of airgel>>
<Weight reduction rate of airgel>
The weight loss rate of the airgel at 300° C. measured in accordance with JIS K-7120 is preferably less than 15%, more preferably 5% or less. By using such an airgel, it is possible to enhance the effects of the present invention.

Note that the weight reduction rate of the airgel can be adjusted by the type and amount of the raw materials, the degree of polymerization of the polymer, etc. For example, in the case of silica airgel, it can be adjusted by selecting the silica component (monomer or oligomer), and more specifically, by using oligomers of tetramer or higher as the raw material and increasing the degree of polymerization of the polymer component. Therefore, it is possible to suppress the weight loss rate of the airgel. Furthermore, it is also possible to suppress the weight loss rate of the airgel by increasing the degree of polymerization of the polymer component by adjusting the type and blending ratio of the solvent, and the type and blending amount of the catalyst.

<<<Foam>>>
The foam is an open cell resin foam having an open cell structure. By using the foam as an open-cell resin foam, the inside of the foam can be sufficiently filled with airgel, and excellent heat insulation properties can be achieved.

<<Components of foam>>
The resin component constituting the foam is not particularly limited and may be any known resin component, including polyolefin resins, polystyrene resins, polyester resins, polyether resins, acrylic resins, polyamide resins, and chlorinated resins. It is preferable that one or more resin components selected from the group consisting of vinyl resin, polycarbonate resin, and fluororesin are included. Moreover, it is more preferable that these resins have a softening temperature of 200° C. or lower. In other words, foams include polyolefin resin foams, polystyrene resin foams, polyester resin foams, polyether resin foams, acrylic resin foams, and polyamide resin foams that have a softening temperature of 200°C or less. , vinyl chloride resin foam, polycarbonate resin foam, or fluororesin foam.

<<Physical properties/properties of foam>>
<Softening temperature of foam>
The softening temperature of the foam can be measured by a known method and is not particularly limited. For example, it can be measured using the method described in JIS K7196:1991 "Softening temperature test method by thermomechanical analysis of thermoplastic films and sheets".

<Air permeability of foam>
The air permeability of the foam is 0.01 cm ³ /cm ² /sec or more, 0.5 cm ³ /cm ² /sec or more, 10 cm ³ /cm ² /sec or more, or 25 cm ³ /cm ² /sec or more. It is preferable. Further, the upper limit of the air permeability of the foam is not particularly limited because the higher it is, the better, but the upper limit of the air permeability of the foam is, for example, 300 cm ³ /cm ² /sec.

Such air permeability can be measured by a known method and is not particularly limited. For example, it can be measured using the method described in JIS L1096-7:2010 "Fabric testing method for woven and knitted fabrics: Method A (Fragile method)". If the measured air permeability (or air permeability) of the resin foam is 0.01 cm ³ /cm ² /sec or more, it is determined that the resin foam has a certain degree of air permeability.

In particular, in the case of 10 cm ³ /cm ² /sec or more, the airgel composite material does not require time-consuming evacuation in the sol solution filling step described below, and an efficient manufacturing method can be achieved.

<Foam density>
The density of the foam is 0.020 g/cm ³ or more, 0.030 g/cm ³ or more, 0.040 g/cm 3 or more, 0.050 g/cm ^{3 or} more, 0.075 g/cm ^{3 or} more, 0.100 g/cm 3 or more cm ³ or more, 0.120 g/cm ³ or more, or 0.275 g/cm ³ or less, 0.250 g/cm ³ or less, 0.240 g/cm ³ or less, 0.230 g/cm ³ or less, 0 It may be .220 g/cm ³ or less, 0.210 g/cm ³ or less, or 0.200 g/cm ³ or less. By setting the density of the foam within this range, it is possible to control the filling amount of airgel so as to exhibit excellent heat insulation properties, while also providing an airgel composite material with excellent flexibility.

<<Preferred structure of foam (open cell resin foam with skin)>>
The foam is a skinned open-cell resin foam (hereinafter simply referred to as a skinned open-cell resin foam), which has a foam layer having open cells and a skin layer having air permeability formed on two opposing surfaces of the foam layer. (sometimes abbreviated as "resin foam") is preferable.

The average cell diameter (RB) of the open cells in a cross section perpendicular to the surface of the skin layer is not particularly limited, but can be, for example, 5 μm to 300 μm, preferably 5 μm to 200 μm, and 5 μm to 100 μm. It is particularly preferable that there be. If the average cell diameter of the open cells contained in the foam layer is within this range, the sol solution will be easily filled in the sol solution filling process described below due to capillary action even under normal pressure, and the process time will be shortened. is shortened.

Furthermore, the size of the airgel contained within the open cells is limited by the average cell diameter of the open cells, and the size of the airgel is also the same.

Since airgel is extremely brittle, it is easily damaged if defects such as cracks are present. The smaller the size of the airgel, the lower the probability that the defects will exist, and therefore the formed airgel is less likely to be damaged.

Furthermore, the smaller the size of the airgel, the better the ability to follow the shape of the resin component during thermoforming, resulting in improved thermoformability.

Therefore, when the average cell diameter of the open cells is within this range, the size of the airgel can be reduced, the probability that the airgel will have defects will be lowered, the shape conformability with the resin component will be increased, and the airgel It is possible to reduce breakage of the material, that is, powder falling off, and improve thermoformability.

Moreover, if the apparent density of the open-cell resin foam is the same, the smaller the cell diameter, the more the number of barriers can be increased. Increasing the number of barriers will be effective against radiation and will reduce the thermal conductivity of the airgel composite since the open cell resin foam will have a lower thermal conductivity.

Preferably, the skin layer includes open cells that reach the surface of the skin layer. In this case, the average cell diameter RA of open cells (see FIG. 1) when the surface of the skin layer is observed from the normal direction, and the open cells of the foam layer (see FIG. 2) in a cross section perpendicular to the surface of the skin layer. ) and the average cell diameter RB (RA/RB) is preferably 1/1000 to 1/2, more preferably 1/100 to 1/2, 1/30 to 1/2, 1 /10 to 1/2, or 1/10 to 1/3. When the ratio of the average cell diameters is within this range, the airgel composite material has high powder drop prevention properties, and has excellent heat insulating properties and flame retardance.

The average cell diameter RA of the open cells contained in the skin layer observed from the normal direction of the surface of the skin layer and the average cell diameter RB of the foam layer can be measured by the following method.
Using a scanning electron microscope (SEM, eg, VHXD-500 manufactured by Keyence Corporation), a cell photograph taken from the normal direction of the epidermal layer and a cell photograph of the cross section of the resin foam are taken. Thereafter, the diameter of each cell is measured using image processing software (for example, Image-ProPLUS (manufactured by MediaCybernetics, ver. 6.3)). More specifically, the SEM image is read and the contrast is adjusted in order to recognize cells based on the contrast. Next, the shape of the cell is read using image processing (recognizing the shape as is, not a perfect circle). Next, select "diameter (average)" as the measurement item. Next, the diameter of each cell is calculated by measuring the diameter passing through the center of gravity of the object every two degrees and taking the average value.

The above-mentioned average cell diameter ratio is determined by the compounding conditions described below (the amount of anionic surfactant as a foaming agent added, the mixing ratio of the main agent and curing agent, the amount of organic blowing agent, foaming auxiliary agent, and nucleating agent). ) and molding conditions (stirring speed, drying temperature), etc. For example, if the blending amount of the anionic surfactant, which is a foaming agent, is reduced, the average cell diameter RB of the open cells in the foam layer in a cross section perpendicular to the surface of the skin layer increases, so that the average cell diameter ratio (RA/RB) tends to become smaller. On the other hand, when the drying temperature during molding is increased, the average cell diameter RA of open cells observed from the normal direction of the surface of the skin layer increases, so the average cell diameter ratio (RA/RB) tends to increase. . Furthermore, by increasing the blending amount of the nucleating agent, the average cell diameter ratio (RA/RB) tends to increase. When the average cell diameter ratio is within this range, the airgel composite material has excellent powder drop prevention properties and therefore excellent heat insulation properties. That is, when there is little powder falling, the airgel, which is a heat insulating material, is less likely to fall out of the foam, and the airgel composite material and airgel molded product can maintain high heat insulation properties.

In addition, in the case where there is little powder falling, the heat insulating effect can be maintained, which is thought to contribute to improving flame retardancy.

Nucleating agents include powders of inorganic compounds such as wet silica, dry silica, talc, mica, and diatomaceous earth; aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, and potassium carbonate. , calcium carbonate, magnesium carbonate, potassium sulfate, barium sulfate, glass beads, polytetrafluoroethylene, tribasic calcium phosphate, magnesium pyrophosphate, calcium stearate, zinc stearate, magnesium stearate; ethylene bisstearamide; , methylene bisstearic acid amide, stearic acid amide, 12-hydroxystearic acid amide; and fatty acid glycerides such as stearic acid triglyceride and stearic acid monoglyceride. These nucleating agents may be used alone or in combination of two or more.

The skinned open-cell resin foam includes a foam layer having open cells as described above, and an air-permeable skin layer formed on two opposing surfaces of the foam layer. Moreover, commercially available open-cell resin foams with skins can be used.

The skin layer is formed by, for example, supplying a foamed composition onto a PET sheet, and forming it into a sheet shape or the like according to the desired thickness of the resin foam using known means such as a doctor knife or a doctor roll. During this process, the surface of the foam layer that comes into contact with the PET sheet and coating equipment such as a doctor knife is altered to form a skin layer.

Moreover, the skin layer can also be formed by producing a foam layer having open cells and then subjecting the foam layer having open cells to heat treatment using a hot press machine or a hot roll machine.

Since the foam layer and the skin layer are integrated, the open cells contained in the foam layer and the open cells contained in the skin layer communicate with each other, and the foam layer also has air permeability. That is, even as an open-cell resin foam with a skin, it has air permeability.

When the foam includes a skin layer, the thickness of the airgel composite is the sum of the thickness of the skin layer and the thickness of the foam layer.

Skin layers are present on two opposing surfaces of the foam layer.

The thickness of the epidermal layer is not particularly limited, but can be, for example, 0.01 to 30 μm, preferably 0.01 to 15 μm, and more preferably 0.01 to 10 μm. When the thickness of the epidermis layer is within this range, powder fall prevention properties are enhanced.

Further, the skin layer includes open cells, and the open cells include those that reach the surface of the skin layer. Therefore, the epidermal layer is permeable to outside air. That is, it has breathability.

In addition, the open cells contained in the skin layer and the open cells contained in the foam layer are connected by communication through holes, and fluid such as outside air can be passed between the open cells contained in the skin layer and the open cells contained in the foam layer. It is possible to move back and forth between the open bubbles that are formed.

Here, although the air permeability of the skin layer alone cannot be measured, it can be determined whether the skin layer has air permeability by measuring the air permeability of the skinned open-cell resin foam through the surface of the skin layer.

The porosity of the skinned open-cell resin foam is calculated by dividing the apparent density of the skinned open-cell resin foam after foaming by the density of the unfoamed raw material resin, subtracting this divisor from 1, and converting it into a percentage. do. The measurement of apparent density is based on JIS K7222:2005 "Foamed plastics and rubber - How to determine apparent density".

The higher the porosity is, the better, since the amount of airgel contained in the airgel composite can be increased. The larger the filling amount of airgel with high heat insulation properties, the higher the heat insulation properties of the airgel composite material.

The porosity is not particularly limited as long as it does not impede the effects of the present invention, but for example, the porosity can be 50 to 99%, preferably 65 to 99%, and 85 to 99%. It is more preferable that When the porosity is within this range, a sufficient amount of airgel can be filled into the skinned open-cell resin foam, making the airgel composite material lightweight and having excellent heat insulation properties. It can be done.

<<Physical properties/properties of airgel composite material>>
<25% compressive load of airgel composite material>
The 25% compressive load of the airgel composite is preferably 10 to 1000 kPa, more preferably 100 to 500 kPa. By using such an airgel composite material, there is little powder falling, and it has excellent moldability and heat insulation performance. The 25% compressive load of the airgel composite can be measured in accordance with JIS K6254:2016 "Vulcanized rubber and thermoplastic rubber - How to determine stress-strain characteristics".

The 25% compressive load of the airgel composite material can be adjusted by the type of raw material, degree of polymerization, solid content ratio of the wet gel, etc. It can also be adjusted by adjusting the types and amounts of the resin components and additives constituting the open-cell resin foam, the density of the foam, the average filling rate of the airgel, etc. For example, in the case of silica airgel, it can be adjusted by selecting the silica component (monomer or oligomer) or the solid content ratio of the wet gel. By using it as a raw material or setting the solid content ratio to 10% or more and 50% or less, it becomes easier to set the 25% compression load to 10 to 1000 kPa.

<<<<<Structure/physical properties/properties of airgel molded product>>>>>
In the airgel molded article, the average filling rate (volume ratio occupied by the filled airgel in the cells) of each cell contained in the airgel foam is preferably 70% or more, and more preferably 90% or more. preferable. When the average filling rate is within this range, the airgel molded product has excellent heat insulation properties.

The airgel composite material for producing the airgel molded article preferably has a 25% compressive load of 10 to 1000 kPa, more preferably 100 to 500 kPa, as measured in accordance with JIS K-6254. Furthermore, the airgel filled in the foam in the airgel composite material preferably has a weight loss rate of less than 15% at 300°C measured in accordance with JIS K-7120, and preferably less than 5%. More preferred. When the 25% compression load and the weight loss rate at 300° C. are within these ranges, there is little powder falling off even after thermoforming and the heat insulation performance is maintained, resulting in an airgel molded product with excellent heat insulation properties.

<<<<<<Method for manufacturing airgel molded article>>>>>>
The airgel molded article can be manufactured by thermoforming an airgel composite material. Hereinafter, one example of a preferred method for manufacturing an airgel molded article will be described.

<<<<Preparation of airgel composite material>>>>
Airgel composites can be manufactured as follows. Here, a case will be described in which the foam is the skinned open-cell resin foam described above.

The method for producing an airgel composite material includes a sol solution filling step of filling an open-cell resin foam with a skin with a sol solution, which is a raw material for airgel, under normal pressure or reduced pressure, and gelling the filled sol solution. and a drying step of drying the wet gel. Each step will be explained in detail below. Note that regarding the description of airgel, silica airgel, which is a preferred example, will be explained in detail as an example. Further, the method for producing an airgel composite material can further include steps other than those described below.

<<<Foam formation process>>>
The foam forming process will be described in detail below, and a commercially available open-cell skinned resin foam can be used as the skinned open-cell resin foam as long as it does not impede the effects of the present invention. Below, the foam forming process in the case of using a polyolefin resin as a raw material will be exemplified.

<<Foam formation process when polyolefin resin is used as raw material>>
<Raw materials>
The polyolefin resin that is the raw material for the skinned open-cell resin foam is not particularly limited, and any known resin can be used. Furthermore, other additives may be added as long as they do not impede the effects of the present invention. An example of a method for producing a polyolefin foam will be described below.

The polyolefin foam contains (A) (A1) polyolefin (excluding ethylene-propylene rubber), (A2) ethylene-propylene rubber and/or styrene thermoplastic elastomer, and (B) nonionic surfactant. It is obtained by impregnating a composition that is a gas at room temperature and pressure in a supercritical state at high temperature and pressure, and then releasing the pressure and foaming.

Examples of the polyolefin (A1) include polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymers, ethylene-α-olefin copolymers, and polymer blends of these. The polyethylene may be any of high density polyethylene, medium density polyethylene, linear low density polyethylene, low density polyethylene, etc., and the polypropylene may be any of atactic, isotactic, syndiotactic, random, etc. Further, polypropylene having a high extensional viscosity such as polypropylene having long chain branches in the main chain skeleton (HMS-PP) which is considered suitable for foaming or polypropylene containing a high molecular weight component and having a wide molecular weight distribution may be used. The copolymer may be a random copolymer or a block copolymer, and may be a thermoplastic resin or a thermoplastic elastomer. Among these, random polypropylene is preferred because it can impart heat resistance to the resulting foam and maintain the flexibility of the resulting foam. The melt flow rate of component (A1) is preferably 0.1 to 5 g/10 min at 230°C and 2.16 kgf, and more preferably 0.3 to 2 g/10 min, since there is no gas escape and foaming is easy ( JISK7210:1999 compliant). Note that ethylene-propylene copolymers include ethylene-propylene copolymers (EPR), which become rubber-like elastic bodies when cured, but this is included in component (A2) and therefore excluded from (A1). (A1) includes a resinous ethylene-propylene copolymer. Further, other thermoplastic polymers may be present as long as they do not impair the properties of the open-cell resin foam of this embodiment.

The ethylene-propylene rubber (A2) is EPR (EPM), which is a copolymer of ethylene and propylene that becomes a rubber-like elastic body when cured; Certain EPDMs are included. Examples of the non-conjugated diene include ethylidenenorbornene, dicyclopentadiene, and 1,4-hexadiene, and any of them may be used in the present invention.

The styrenic thermoplastic elastomer (A2) may be any block copolymer in which styrene is bonded to one or both ends of a polymer consisting of a hydrocarbon chain, such as a block copolymer of styrene and butadiene, isoprene, isobutylene, etc. or further hydrogenated block copolymers thereof, such as styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butylene-styrene block copolymer (SEBS) obtained by hydrogenating SBS, and styrene-isoprene-styrene block copolymer (SIS). ), and styrene ethylene propylene styrene block copolymer (SEPS) hydrogenated with SIS, styrene isoprene butadiene isoprene styrene block copolymer, and styrene ethylene ethylene propylene styrene block copolymer (SEEPS) hydrogenated with SIS, styrene vinyl isoprene styrene block copolymer, and hydrogenated products thereof, styrene isobutylene styrene block copolymer, styrene butadiene block copolymer, and hydrogenated products thereof, styrene isobutylene block copolymer, and hydrogenated products thereof, etc., which may be used alone or in combination. You can also do that.

Regarding the component (A2), the higher the average molecular weight, the better. Further, it may be used after being oil-extended with process oil or the like. Component (A2) is used as it is without performing a crosslinking reaction.

(B) Nonionic surfactants include alkyl polyethers such as polyoxyethylene (polyoxypropylene) alkyl ether, fatty acid polyether esters such as polyoxyethylene (polyoxypropylene) fatty acid ester, and dipolyoxyethylene (dipolyoxypropylene)alkylamines such as di(dioxyethylene)stearylamine, alkylpolyether amines such as polyoxyethylene(polyoxypropylene)dialkylamine, polyoxyethylene(polyoxypropylene)alkylalkylene diamine; Sorbitan esters such as polyoxyethylene (polyoxypropylene) sorbitan ester and sorbitan alkyl ester, polyoxyethylene (polyoxypropylene) alkyl glyceryl ether, fatty acid (poly)glyceryl, such as monoglyceryl stearate, polyoxyethylene (polyoxy Examples include alkylglyceryl polyethers or esters such as propylene) fatty acid glyceryl, alkanolamides such as fatty acid (di)ethanolamide, and mixtures of a plurality of these. The number of carbon atoms in the alkyl, fatty acid, and alkylene is preferably 10 or more from the viewpoint of compatibility with the polyolefin polymer composition, such as C12 (lauryl or laurylate, etc.), C18 (stearyl or stearate, etc.) , C22 (such as behenyl or behenylate), and the like. Further, the number of repeating units of oxyalkyl such as polyoxyethylene and polyoxypropylene is preferably 1 to 20, and more preferably 10 or less. The number of repeating units of polyglyceryl is also preferably 1 to 20, more preferably 10 or less. Furthermore, one type or a mixture selected from alkyl polyether amines, fatty acid glyceryl, and fatty acid (di)ethanolamides can be preferably used, and higher alcohols such as stearyl alcohol may also be added.

Component (A) used in this embodiment includes (A1) polyolefin (excluding ethylene-propylene rubber) 50 to 95% by weight, preferably 60 to 90% by weight, more preferably 65 to 85% by weight, and ( A2) A polymer composition containing 5 to 50% by weight, preferably 10 to 40% by weight, more preferably 15 to 35% by weight of ethylene-propylene rubber and/or styrenic thermoplastic elastomer. If the proportion of (A1) exceeds 95% by weight and the proportion of (A2) is less than 5% by weight, there is a problem that not only is it difficult to obtain sufficient flexibility in the foam, but also it is difficult to obtain a highly foamed product. On the other hand, if the proportion of (A1) is less than 50% by weight and the proportion of (A2) exceeds 50% by weight, it is still difficult to obtain a highly foamed product, and there is a problem that the obtained foam has a large shrinkage.

The amount of component (B) required is 0.2 to 10 parts by weight per 100 parts by weight of the polymer composition (A), preferably 0.3 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight. Department. If component (B) is less than 0.2 parts by weight, the required open cell formation cannot be obtained, and only a foam with low air permeability can be obtained. On the other hand, if it exceeds 10 parts by weight, the foam will break too much and the foam will shrink.

In the present invention, a foamable composition is prepared by mixing components (A1), (A2), and (B), and optionally optional components by a mixing means suitable for mixing polymeric materials. . At this time, as an optional component, liquid paraffin may be added to the foamable composition according to the purpose of use, in order to impart appropriate properties to the resulting foam or to facilitate the production and processing of the foam. , hydrocarbon process oils, higher fatty acid glycerin esters, higher fatty acid amides; wet silica, dry silica, talc, mica, diatomaceous earth, aluminum oxide, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, hydroxide. Aluminum, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, potassium sulfate, barium sulfate, glass beads, polytetrafluoroethylene, tribasic calcium phosphate, magnesium pyrophosphate, calcium stearate, zinc stearate, magnesium stearate, ethylene bis Bisamide compounds such as stearamide, methylene bisstearamide, nucleating agents such as stearamide, 12-hydroxystearamide, stearic acid triglyceride, stearic acid monoglyceride; phosphate ester, melamine phosphate or piperazine phosphate, Flame retardants such as aluminum hydroxide, magnesium hydroxide, antimony oxide, zinc carbonate, chlorinated paraffins, hexachlorocyclopentadiene; aromatic amines, benzimidazoles, dithiocarbamates, phenolic compounds, phosphites, etc. anti-aging agent; 2,6-di-t-butylphenol, 2,6-di-t-butyl-4-ethylphenol, 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 1, Antioxidants such as 1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane; conductive materials such as conductive carbon black, copper powder, nickel powder, and tin oxide; carbon black , organic pigments, dyes, and coloring agents such as masterbatches containing them; as well as fillers such as silica, alumina, titanium oxide, and the various additives listed above that function as fillers. can.

The substance that is a gas at room temperature and normal pressure and which is impregnated into the foamable composition in a supercritical state may be any substance that can permeate the polymer in the foamable composition in this supercritical state, such as nitrogen, helium, Examples include carbon dioxide, propane, butane, and mixed gases thereof. Carbon dioxide and nitrogen are preferred, and carbon dioxide is particularly preferred because they are easy to handle, have high safety, and provide an excellent working environment.

<Foaming process>
Under the following conditions, the polymer in the foamable composition is impregnated with a substance that is a gas at normal temperature and pressure, and then the pressure is released to form open cells. Foaming can be carried out to form open cells by reducing the pressure at a rate of decrease, usually from 10 to 30 MPa/s. Since an open-cell resin foam is directly obtained in the foaming step, there is no need for a subsequent step of breaking closed cells to open cells using mechanical stress.

The temperature at which the foamable composition is impregnated with a substance that is a gas at normal temperature and pressure is the temperature that brings the substance into a supercritical state, since a functional foam can be efficiently obtained. It is particularly preferable that the temperature be 20 to 40° C. higher than the crystallization peak temperature of the polymer in the foamable composition as measured by the method. Here, the supercritical state is a state exhibiting properties intermediate between a gas state and a liquid state.

In addition, the impregnation pressure is preferably 8 to 15 MPa, particularly in order to bring the impregnated substance, which is a gas at room temperature and pressure, into a supercritical state in order to completely impregnate and obtain fine cells. In order to make it difficult for gas to escape, 10 to 15 MPa is more preferable.

The time for impregnating the foamable composition with a substance that is a gas at room temperature and pressure varies depending on the required amount of impregnation and the impregnation temperature and pressure, but is usually 3 to 30 minutes, preferably 5 to 20 minutes.

When foaming the foamable composition into open cells, the foaming ratio is preferably 5 times or more. If it is less than 5 times, the problem arises that excellent flexibility cannot be imparted to the resulting foam. The upper limit of the magnification is not particularly limited, but from the viewpoint of mechanical strength, it is 100 times or less, preferably 80 times or less, and more preferably 50 times or less.

A molded body of an open-celled resin foam with a skin can be obtained by foaming to a foaming ratio of 5 times or more as described above and by extrusion molding. As the extruder, a single-screw tandem extruder is used, and depending on the case, it may be used in combination with a twin-screw extruder. By extrusion molding, it is possible to obtain a skinned open-cell resin foam in which the foam layer and the skin layer are integrated without going through an adhesion or fusing process. Since there is no adhesion or fusing process, there is no fear that the thermal conductivity of the material used for sealing will affect the heat insulation properties, and the number of man-hours does not increase, so the work efficiency will not decrease.

Let's talk about extrusion molding. The extrusion molding apparatus of the present invention includes: an apparatus for melting a molding material containing a thermoplastic resin; an apparatus for mixing a gaseous material in a supercritical state at normal temperature and normal pressure into the melting molding material at room temperature and normal pressure; The molding apparatus is equipped with an extrusion device that heats and compresses the molten molding material mixed with gaseous materials under pressure and extrudes it from a die. The above-mentioned mixing device is installed so that a gaseous material in a supercritical state at room temperature and pressure is mixed into a socket provided in the barrel in the longitudinal direction of the extruder.

That is, supercritical carbon dioxide is supplied from the inlet to the polymeric material melted and extruded by the screw, and mixed to form a single-phase solution.Then, this single-phase solution is uniformly dispersed into the polymeric material. The fluid stream is then extruded by passing the liquid mixture of polymeric material and very small bubbles through a die at elevated temperature while suppressing bubble growth.

<Cutting>
The resulting skinned open-cell resin foam can be processed into a predetermined size. Cells with an open cell structure are exposed on the cut surface. The sol solution is filled from the exposed bubbles.

Through the above foam forming process, a skinned open-cell resin foam in which a skin layer having open cells is formed is obtained.

<<Sol solution filling process>>
The details of the method for producing silica airgel, which is a preferred example, will be explained below as an example, but the present invention is not limited to silica airgel.

<Sol solution>
As a silicone raw material for silica airgel, silicone alkoxide or a derivative thereof, or an alkali metal silicate salt can be used, and is mixed with an aqueous solvent to form a sol solution.

The silicone raw material is not particularly limited as long as it does not impede the effects of the present invention. Examples of silicone alkoxides and derivatives thereof include tetramethoxysilane, tetraethoxysilane, tetramethoxysilane oligomer, tetraethoxysilane oligomer, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and vinyltrimethoxysilane. Examples include methoxysilane, vinyltriethoxysilane, hexyltrimethoxysilane, and monohexyltriethoxysilane. Examples of the alkali metal silicate include potassium silicate and sodium silicate. The silicone raw materials can be used in combination. When using a plurality of them, the combination and blending ratio can be selected depending on the purpose.

For hydrolysis of the silicone raw material, it is preferable to use water and a solvent that is compatible with water and dissolves the silicone raw material. Examples of solvents include alcohols such as methanol, ethanol, isopropanol, and butanol, aliphatic diols such as ethanediol, propanediol, butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol, hydrogenated bisphenol A, and bisphenol. A, aromatic diol or alicyclic diol such as cyclohexane diol, polyhydric alcohol such as glycerin, diglycerin, trimethylolpropane, trishydroxymethylaminopentane, pentaerythritol, dipentaerythritol, hexamethylolmelamine, hexane, toluene, Examples include chloroform, diethyl ether, tetrahydrofuran, ethyl acetate, acetone, and acetonitrile. These solvents may be used alone or in combination of two or more.

In order to efficiently hydrolyze the silicone raw material, it is preferable to add a catalyst to the reaction system in advance. The catalyst is not particularly limited as long as it does not impede the effects of the present invention. For example, acidic catalysts include formic acid, acetic acid, succinic acid, malic acid, citric acid, hydrochloric acid, nitric acid, boric acid, sulfuric acid, carbonic acid, Examples of basic catalysts include metal oxides and/or hydroxides such as sodium hydroxide and potassium hydroxide, dimethylamine, triethylamine, N,N-dimethylbenzylamine, aniline, and 1,5-naphthalene. Examples include aliphatic and/or aromatic amines such as diamines, ammonia, naphthenic acids of divalent metals, and hydroxides of divalent metals. These catalysts may be used alone or in combination of two or more.

<Filling method>
The method for filling the sol solution is not particularly limited as long as it is carried out under normal pressure or reduced pressure, and any known method can be used. For example, a method may be used in which the skinned open-cell resin foam obtained by the method described above is completely impregnated with a prepared sol solution under reduced pressure. In particular, when the air permeability is 10 cm ³ /cm ² /sec or more, filling under normal pressure is possible.

Specifically, let us take as an example a sol solution in which tetramethoxysilane (hereinafter referred to as TMOS): methanol: water: catalyst (ammonia) is mixed at a molar ratio of 1:7.2:4:0.01. By placing the foam in a separable flask and gradually introducing the sol solution, it is possible to completely immerse the foam in the sol solution and fill the foam with the sol solution. Leave it as it is for 2 to 3 hours until it becomes a gel.

Reactive functional groups such as unreacted hydroxyl groups, carboxyl groups, and amino groups remaining in the open-cell resin foam may react with the hydrophobizing agent described below. Since the presence of a large amount of reactive functional groups may inhibit the hydrophobization reaction of the wet gel, the reactive functional groups remaining in the open-cell resin foam are inactivated in the prior step of the sol solution filling process. It's okay. The method for inactivating the reactive functional group is not particularly limited, and any known method can be used.

<Gelification>
In the sol solution filled in the foam, TMOS is hydrolyzed by water and a catalyst through a sol-gel reaction, and the sol solution passes through a sol state to form a wet gel. Here, the wet gel refers to a gel that has become solid while containing liquid such as the residual liquid of the sol solution after gelation.

A wet gel is formed inside the open cells in the foam by a sol-gel reaction due to hydrolysis of the silicone alkoxide or its derivative.

After forming the wet gel, there may be a step of removing water and unreacted substances in the wet gel. Examples of the solvent used in this step include alcohols such as methanol, ethanol, isopropanol, and butanol, acetone, and acetonitrile. The process is completed by dipping the wet gel-filled foam into the solvent and replacing the solvent several times.

The method may include a step of hydrophobizing the OH groups on the surface of the silica airgel using a hydrophobizing agent having a hydrophobic group and a functional group that reacts with a silanol group having hydrophilic properties. The hydrophobizing agent used has a functional group that reacts with silanol groups and a hydrophobic group. Examples of functional groups that react with silanol groups include halogens, amino groups, imino groups, carboxyl groups, alkoxyl groups, and hydroxyl groups. Examples of the hydrophobic group include alkyl groups, phenyl groups, and fluorides thereof. The hydrophobizing agent may have only one type of each of the above-mentioned functional group and hydrophobic group, or may have two or more types of the above-mentioned functional group and hydrophobic group. For example, organic compounds such as hexamethyldisilazane, hexamethyldisiloxane, trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane, triethylmethoxysilane, dimethyldichlorosilane, dimethyldiethoxysilane, methyltrichlorosilane, ethyltrichlorosilane, etc. Examples include silane compounds, and organic compounds such as carboxylic acids such as acetic acid, formic acid, and succinic acid, and alkyl halides such as methyl chloride. Only one type of hydrophobizing agent may be used, or two or more types may be used.

A coupling agent may be added in order to increase the adhesion between the airgel and the continuous resin foam and to prevent the airgel from falling off. The coupling agent is not particularly limited as long as it can react with both the silanol groups on the surface of the airgel and the reactive functional groups such as hydroxyl groups, carboxyl groups, and amino groups remaining in the continuous resin foam, and any suitable coupling agent can be used. Any coupling agent can be used. As the coupling agent, it is preferable to use a silane coupling agent, such as vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, -Glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltri Examples include methoxysilane, 3-isocyanatepropyltriethoxysilane, and tris-(trimethoxysilylpropyl)isocyanurate.

<Drying process>
The present invention includes a drying step of drying the wet gel. A known drying method can be used and is not particularly limited. When drying a wet gel, supercritical fluid drying is preferred because silica airgel is less likely to break down. Examples of supercritical fluid drying include a method in which all of the solvent is removed under conditions of 80° C. and about 20 MPa while replacing it with carbon dioxide, which has a lower critical point than the solvent.

<<<<Thermoforming of airgel composite material>>>>
The airgel composite is deformed into a desired shape while applying external force and heat (for example, applying heat while fitting into a heated mold). Thereafter, the airgel molded product (airgel composite thermoformed product) is manufactured by cooling if necessary.

The application of external force and heat during thermoforming is not particularly limited, as long as the conditions are such that the airgel composite can be sufficiently deformed, taking into consideration the material of the airgel composite (especially the material/softening point of the foam). However, it can be carried out under conditions such as, for example, 100°C or higher, 110°C or higher, 120°C or higher, or 130°C or higher.

The thermoforming of the airgel composite is preferably vacuum forming. Vacuum forming is a molding method that reduces the pressure in the space between the airgel composite material, which has been softened by heating to a temperature above its softening point, and a mold, thereby bringing the mold and the airgel composite into close contact.

Thermoforming of the airgel composite may be carried out with the airgel composite bonded to other components, but may be performed without bonding any other components to the airgel composite (i.e., components other than the airgel composite). It is preferable to carry out the process (without bonding). In this case, a single airgel composite may be thermoformed, but it is also preferable to thermoform a plurality of airgel composites in a stacked state.

After thermoforming only the airgel composite material, a step such as providing other members on the resulting thermoformed airgel composite material (for example, bonding them by thermocompression/bonding them using an adhesive) may be performed. , does not need to be provided.

<<<<<Uses of airgel molded products>>>>>
Airgel molded articles have less powder falling, can be formed into complex shapes (for example, can have curved surfaces and corners), and have excellent heat insulation performance. More specifically, by using open-cell thermoplastic resin foam, thermoforming processes such as vacuum forming are possible, making it possible to manufacture airgel molded products with complex shapes that cannot be handled with existing insulation materials. Can be done. In addition, compared to existing insulation materials, it has superior heat insulation and heat shielding performance, so the thickness of the insulation material can be reduced. Therefore, when it is placed in a container as a heat insulating material, the storage capacity of the container can be increased. When a composite material of an open-cell resin foam with a skin and an airgel is used, the skin layer of the foam can prevent adhesives and the like from penetrating into the pores of the airgel particles. Since it is possible to suppress the airgel from falling off (powder falling), aging deterioration of insulation performance is minimized, and equipment contamination can be suppressed. Since the skin layer is smooth, it is easy to apply adhesive.

As described above, the airgel molded product can be used as a heat insulating appliance. Furthermore, the airgel molded product can be used as a heat-retaining member/cold-retaining member, etc., and can be installed in various devices and appliances that require heat insulation performance. For example, cold/warm boxes for food, medical care, and pharmaceuticals that have heat insulating members and/or cold insulating members containing airgel moldings, cold/refrigerated equipment such as freezers/refrigerators, freezer/refrigerated showcases, ice makers, and kitchen equipment; It is possible to configure equipment, etc.

Hereinafter, the airgel molded article of the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

<<<<Method for manufacturing open-cell resin foam>>>>
<<<Method for manufacturing polyolefin foam with skin>>>
(polymer resin)
・Random type polypropylene ・Low density polyethylene ・EPDM (ethylene content 29.5%, diene content 5%)
(Additive)
・Nonionic surfactant (polyoxyethylene stearylamine)
・Nucleating agent (wet silica)
・Phenolic antioxidant

<<Polyolefin foam with skin 1>>
<Resin foam raw material preparation, foam formation process>
58 parts by weight of random polypropylene, 15 parts by weight of low-density polyethylene, 20 parts by weight of EPDM (ethylene content 29.5%, diene content 5%), 1.5 parts by weight polyoxyethylene stearylamine, 5 parts by weight wet silica, phenol. After melt-kneading and impregnating carbon dioxide in a supercritical state with 0.2 parts by weight of a system antioxidant, the foam was foamed by releasing the pressure, and a skinned polyolefin foam 1 was obtained by extrusion molding. The manufacturing conditions are that the impregnation temperature is 180°C, the impregnation pressure is 13 MPa, and the impregnation time is 20 minutes.

<<Polyolefin foam with skin 2>>
A skinned polyolefin foam 2 was obtained in the same manner as the skinned polyolefin foam 1 except that the manufacturing conditions such as impregnation pressure and impregnation time were adjusted so that the density was 0.30 g/cm ³ .

<<Polyolefin foam with skin 3>>
A skinned polyolefin foam ³ was obtained in the same manner as the skinned polyolefin foam 1 except that the manufacturing conditions such as impregnation pressure and impregnation time were adjusted so that the density was 0.10 g/cm 3 .

<<Polyolefin foam with skin 4>>
A skinned polyolefin foam 4 was obtained in the same manner as the skinned polyolefin foam 1 except that the amount of the nucleating agent was changed to 7 parts by weight.

<<Polyolefin foam with skin 5>>
A skinned polyolefin foam 5 was obtained in the same manner as the skinned polyolefin foam 1 except that the amount of the nucleating agent was changed to 3 parts by weight.

<<Polyolefin foam with skin 6>>
A skinned polyolefin foam 6 was obtained in the same manner as the skinned polyolefin foam 1 except that the manufacturing conditions such as impregnation pressure and impregnation time were adjusted so that the density was 0.40 g/cm ³ .

<<Polyolefin foam with skin 7>>
A skinned polyolefin foam 7 was obtained in the same manner as the skinned polyolefin foam 1 except that the manufacturing conditions such as impregnation pressure and impregnation time were adjusted so that the density was 0.07 g/cm ³ .

<<<Method for manufacturing polyvinyl chloride foam with skin>>>
(polymer resin)
・Vinyl chloride resin (additive)
・Calcium carbonate ・Phenol antioxidant

<<Skinned polyvinyl chloride foam>>
<Resin foam raw material preparation, foam formation process>
100 parts by weight of vinyl chloride resin, 6 parts by weight of calcium carbonate, and 3 parts by weight of phenolic antioxidant were melt-kneaded, nitrogen was used as a foaming agent, and the density of the foam was 0.15 g/ ^cm3 . The mixture was injected through the injection port of an extruder, and a polyvinyl chloride foam with a skin was obtained by extrusion molding.

<<Production method of polyethylene terephthalate foam with skin>>
(polymer resin)
・Polyethylene terephthalate resin (additive)
・Phenolic antioxidant ・Fluorine foaming agent

<<Polyethylene terephthalate foam with skin>>
<Resin foam raw material preparation, foam formation process>
100 parts by weight of polyethylene terephthalate resin was melt-kneaded with 5 parts by weight of a phenolic antioxidant, and a fluorine-based foaming agent was injected from the injection port of the extruder so that the density of the foam was 0.15 g/ ^cm3 . A skinned polyethylene terephthalate foam was obtained by extrusion molding.

<<<<Method for manufacturing airgel composite material>>>>
(Raw material for silica airgel)
・Silicone raw material 1
Tetrafunctional methoxysilane oligomer (average tetramer)
・Silicone raw material 2
Tetrafunctional methoxysilane oligomer (average dimer)
・Silicone raw material 3
Tetrafunctional ethoxysilane oligomer (average dimer)
・Silicone raw material 4
Bifunctional methoxysilane oligomer (average tetramer)
・Silicone raw material 5
Tetramethoxysilane (solvent)
・Methanol (manufactured by Wako Pure Chemical Industries)
・Ethanol (manufactured by Wako Pure Chemical Industries, Ltd.)
・Ion exchange water, electrical resistivity 1× ¹⁰ Ω・cm or more (catalyst)
25% ammonia water (manufactured by Wako Pure Chemical Industries, Ltd.)

<<Example 1>>
(Sol solution preparation)
Silicone raw material 1 was used as a base material, and 45 moles of methanol, 25 moles of ion-exchanged water, and 0.01 mole of catalyst were mixed with 1 mole of the base material to prepare sol solution 1.

(Sol solution filling process)
The skinned open-cell resin foam was cut into a size that could be stored in a separable flask and stored with the skin layer still attached. The prepared sol solution 1 was added until the skinned open-cell resin foam was completely immersed, and the mixture was allowed to stand under normal pressure for 3 hours to obtain a skinned open-celled resin foam filled with wet gel.

The resulting open-celled resin foam with a skin filled with the wet gel was immersed in ethanol, and the ethanol was repeatedly exchanged while stirring to perform solvent replacement for 24 hours. Next, in order to make the gel surface hydrophobic, it was immersed in an ethanol solution of hexamethyldisilazane (concentration 20% by mass) and subjected to hydrophobization treatment for 24 hours while stirring.

(drying process)
The skinned open-cell resin foam whose gel surface had been made hydrophobic was impregnated in carbon dioxide at 80° C. and 20 MPa, and supercritical fluid drying was performed for 12 hours.
As described above, an airgel composite material of Example 1 was obtained, in which the inside of the skinned polyolefin foam 1 was filled with the silica airgel 1. The airgel filling rate in the airgel composite was 95%.

<<Example 4>>
Instead of polyolefin foam 1 with skin, polyolefin foam 2 with skin is used, and instead of sol solution 1, silicone raw material 2 is used as the main material, and for 1 mol of main material, 9 mol of methanol and 5 mol of ion exchange are used. An airgel composite material in which silica airgel 2 was filled inside a skinned polyolefin foam 2 was obtained in the same manner as in Example 1, except that sol solution 2 containing water and 0.1 mole of catalyst was used.

<<Example 5>>
Instead of the skinned polyolefin foam 1, a skinned polyolefin foam 3 is used, and instead of the sol solution 1, the silicone raw material 2 is used as the base material, and for 1 mole of the base material, 50 moles of methanol and 30 moles of ion exchange Silica airgel 3 was filled inside the skinned polyolefin foam 3 in the same manner as in Example 1, except that a sol solution 3 containing water, 0.5 mol of silicone raw material 4, and 0.0025 mol of catalyst was used. An airgel composite material was obtained.

<<Example 6>>
Instead of sol solution 1, silicone raw material 3 was used as the main ingredient, and sol solution 4 was used, in which 30 mol of ethanol, 20 mol of ion-exchanged water, and 0.0025 mol of catalyst were mixed with 1 mol of the main ingredient. In the same manner as in Example 1, an airgel composite material was obtained in which the inside of the skinned polyolefin foam 1 was filled with silica airgel 4.

<<Comparative Example 1>>
Instead of the skinned polyolefin foam 1, a skinned polyolefin foam 6 is used, and instead of the sol solution 1, the silicone raw material 5 is used as the base material, and for 1 mole of the base material, 2 moles of methanol and 1 mole of ion exchange are used. An airgel composite material in which silica airgel 5 was filled inside a skinned polyolefin foam 6 was obtained in the same manner as in Example 1, except that the sol solution 5 containing water and 0.25 mol of catalyst was used.

<<Comparative Example 2>>
Instead of the polyolefin foam 1 with a skin, the polyolefin foam 7 with a skin is used, and instead of the sol solution 1, the silicone raw material 2 is used as the base material, and for 1 mol of the base material, 110 mol of methanol and 70 mol of ion exchange are used. An airgel in which silica airgel 6 was filled inside a skinned polyolefin foam 7 in the same manner as in Example 1, except that a sol solution 6 containing water, 2 mol of silicone raw material 4, and 0.002 mol of catalyst was used. Obtained composite material.

<<Comparative Example 3>>
Instead of sol solution 1, silicone raw material 5 was used as the main ingredient, and sol solution 5 was used in which 2 mol of methanol, 1 mol of ion exchange water, and 0.25 mol of catalyst were mixed for 1 mol of the main ingredient. In the same manner as in Example 1, an airgel composite material was obtained in which the inside of the skinned polyolefin foam 1 was filled with silica airgel 5.

<<Examples 2, 3, 7-9, Comparative Example 4>>
An airgel composite material in which silica airgel 1 was filled inside an open-cell resin foam was obtained in the same manner as in Example 1, except that the open-cell resin foam shown in each table was used.

<<<Manufacture of airgel molded products>>>
<<Example 1>>
An airgel composite material in which silica airgel 1 was filled inside a skinned polyolefin foam 1 was placed in a mold heated to 130°C, and the pressure was reduced to vacuum and molded into a predetermined shape to obtain an airgel molded product.

<<Preparation of Examples 2-3, 6-8, Comparative Example 4>>
Airgel molded articles were obtained in the same manner as in Example 1, except that the open-cell resin foams shown in each table were used.

<<Preparation of Examples 4-5 and Comparative Examples 1-3>>
Airgel molded articles were obtained in the same manner as in Example 1, except that the airgel and open-cell resin foam shown in each table were used.

The open cell resin foam used in Comparative Example 4 was made of a thermosetting resin, and the open cell resin foams used in other Examples and Comparative Examples were made of a thermoplastic resin. .

<<<Evaluation of airgel, foam, and airgel composite materials>>>
The airgel, foam, and airgel composite used in each Example and Comparative Example were evaluated according to the method shown below. The results of each evaluation are shown in the table.

<<Weight reduction rate of airgel>>
The weight loss rate of the airgel was measured according to the following method and evaluated according to the evaluation criteria.
<Evaluation method>
Measurements were made in accordance with JIS K7120 "Method for Thermogravimetric Measurement of Plastics" using a simultaneous differential thermogravimetric measuring device (manufactured by Hitachi High-Tech Science Co., Ltd.: STA7200), and the results were evaluated according to the evaluation criteria.
<Measurement conditions>
The temperature was increased from 20°C to 300°C at a heating rate of 10°C per minute.
<Evaluation criteria>
"○" indicates "weight reduction rate is 5% or less,""△" indicates "weight reduction rate is more than 5% and 15% or less," and "x" indicates "weight reduction rate exceeds 15%."

<<Average cell diameter ratio of foam>>
The average cell diameter ratio of the foam was calculated according to the following method.
<Evaluation method>
Cell photographs were taken from the normal direction of the epidermal layer using a scanning electron microscope (SEM, VHXD-500, manufactured by Keyence Corporation). Thereafter, the SEM image was read using image processing software Image-ProPLUS (manufactured by MediaCybernetics, 6.3 ver.), and the contrast was adjusted in order to recognize cells based on the contrast. Next, the shape of the cell is read using image processing (recognizing the shape as is, not a perfect circle). Next, select "diameter (average)" as the measurement item. Next, the diameter passing through the center of gravity of the object was measured every two degrees, and the average value was used to calculate the diameter of each cell, which was defined as RA.
A cell photograph was similarly taken for a cross section perpendicular to the surface of the epidermis layer, and RB was determined.

<<Air permeability of foam>>
The air permeability of the foam was measured according to the method described below and evaluated according to the evaluation criteria.
<Evaluation method>
Measured using a woven fabric air permeability tester (manufactured by Toyo Seiki Kogyo Co., Ltd.: KM-40P) in accordance with JIS L1096-7:2010 "Fabric test method for woven and knitted fabrics: Method A (Frazier method)" The items were evaluated according to the evaluation criteria.
<Evaluation criteria>
“◎” means “air permeability is 25 cm ³ /cm ² /sec or more”, “○” means “air permeability is 10 cm ³ /cm ² /sec or more but less than 25 cm ³ /cm ² /sec”, “△” means "Air permeability is 0.5 cm ³ /cm ² /sec or more and less than 10 cm ³ /cm ² /sec", "△△" means "air permeability is 0.01 cm ³ /cm ² /sec or more and less than 0.5 cm ³ /cm2"/sec" and "△△△" indicate "less than 0.01 cm ³ /cm ² /sec", respectively.

<<25% compressive load of airgel composite>>
The 25% compressive load of the airgel composite material was measured according to the following method and evaluated according to the evaluation criteria.
<Evaluation method>
Measurements were made in accordance with JIS K6254:2016 "Vulcanized rubber and thermoplastic rubber - How to determine stress-strain properties" and evaluated in accordance with evaluation criteria.
<Evaluation criteria>
"○" means "25% compression load is more than 100kPa and less than 500kPa", "△" means "25% compression load is more than 10kPa and less than 100kPa, or more than 500kPa and less than 1000kPa", "×" means "25% compression load is more than 1000 kPa or less than 10 kPa" respectively.

<<<Evaluation of airgel molded product>>>
The airgel molded articles according to each Example and Comparative Example were evaluated according to the method shown below. The results of each evaluation are shown in the table.

<<Moldability>>
The moldability was measured according to the method described below and evaluated according to the evaluation criteria.
<Evaluation method>
The test piece is placed in a mold that has been heated to a temperature above the softening point of the open-cell resin foam, and the pressure is reduced to vacuum to form it into a predetermined shape. The weight change rate was calculated from the test piece weight before and after molding. Weight change rate (%) was calculated as (weight before test (g) - weight after test (g))/weight before test (g) x 100. The larger the weight change rate, the more the airgel falls off from the foam and the more the airgel or foam decomposes due to heating.
<Evaluation criteria>
"◎" means "weight change rate is 3% or less", "○" means "weight change rate is more than 3% but not more than 10%", "△" means "weight change rate is more than 10% and not more than 15%" , "x" indicates "the weight change rate exceeds 15%, or the test piece cannot be molded into a predetermined shape", respectively.

<<Average filling rate>>
The average filling rate was measured according to the method described below and evaluated according to the evaluation criteria.
<Evaluation method>
The sample was cut in a direction perpendicular to the surface of the epidermal layer, and a cell photograph of the cross section perpendicular to the surface of the epidermal layer was taken using a scanning electron microscope (SEM, manufactured by Keyence Corporation, VHXD-500). Thereafter, the SEM image was read using the image processing software Image-ProPLUS (manufactured by MediaCybernetics, 6.3 ver.), and the contrast was adjusted in order to recognize the airgel based on the contrast. Next, the shape of the airgel is read using image processing (recognizing the shape as is, not a perfect circle). Next, select "area" as the measurement item. Next, the area of the object was measured and the sum of the areas was calculated. The same method was repeated nine times, and the sum of the values was taken as the volume VA of the airgel filled in the bubbles. In addition, the volume VB of the portion of the bubble that was not filled with airgel was calculated using the same evaluation method as described above. The average filling rate (%) was calculated as VA/(VA+VB)×100. The smaller the average filling rate, the more the airgel falls off from the molded airgel and the more the airgel decomposes due to heating.
<Evaluation criteria>
"○" indicates "average filling rate is over 90%", "△" indicates "average filling rate is over 70% and 90% or less", and "x" indicates "average filling rate is 70% or less". .

<<Insulation>>
The heat insulation properties were measured according to the following method and evaluated according to the evaluation criteria.
<Evaluation method>
The sample was left standing on a heater heated to 60° C. for 5 minutes, and the surface temperature of the sample was measured after 5 minutes. The temperature change per unit thickness was calculated from the sample thickness and surface temperature. The temperature change (°C) per unit thickness was calculated as (heater temperature 60 (°C) - sample surface temperature (°C))/sample thickness.
<Evaluation criteria>
"◎" means "Temperature change per unit thickness exceeds 10℃", "○" means "Temperature change per unit thickness exceeds 5℃ and 10℃ or less", "△" means "Temperature change per unit thickness" is more than 2°C but not more than 5°C,” and “x” means “the temperature change per unit thickness is not more than 2°C.”

Claims (11)

An airgel molded article obtained by thermoforming an airgel composite material in which airgel is filled inside an open cell resin foam,
The open cell resin foam contains a thermoplastic resin,
The weight loss rate of the airgel at 300°C measured in accordance with JIS K-7120 is less than 15%,
An airgel molded article, wherein the airgel composite material has a 25% compressive load of 10 to 1000 kPa as measured in accordance with JIS K-6254. The open cell resin foam is a skinned open cell resin foam having a foam layer having open cells and a skin layer formed on two opposing surfaces of the foam layer,
The skin layer includes open cells that reach the surface of the skin layer,
The average cell diameter RA of open cells in the surface of the skin layer observed from the normal direction of the surface of the skin layer, and the average cell diameter RB of the open cells in the foam layer in a cross section perpendicular to the surface of the skin layer. The airgel molded article according to claim 1, wherein the ratio (RA/RB) of , is 1/1000 to 1/2. The open-cell resin foam has an air permeability of 0.01 cm ³ /cm ² /sec. The airgel molded article according to claim 1 or 2, which is as follows. The open-cell resin foam is made of polyolefin resin, polystyrene resin, polyester resin, polyether resin, acrylic resin, polyamide resin, vinyl chloride resin, polycarbonate resin, fluorine resin, and a polyolefin resin whose softening temperature is 200° C. or lower. The airgel molded article according to claims 1 to 3, comprising at least one type of resin. A heat insulating appliance comprising the airgel molded article according to any one of claims 1 to 4. A refrigerator-freezer comprising a heat insulating member and/or a cold insulating member comprising the airgel molded article according to any one of claims 1 to 4. A cold/warm container comprising a heat insulating member and/or a cold insulating member containing the airgel molded article according to any one of claims 1 to 4. A method for producing an airgel molded article according to any one of claims 1 to 4, comprising:
A method for producing an airgel molded article, comprising the step of thermoforming the airgel composite. The method for producing an airgel molded article according to claim 8, wherein the thermoforming is vacuum molding. The method for producing an airgel molded article according to claim 8 or 9, characterized in that the airgel composite is thermoformed without bonding any member other than the airgel composite. An airgel composite material in which airgel is filled inside an open cell resin foam,
The open cell resin foam contains a thermoplastic resin,
The airgel has a weight loss rate of less than 15% at 300°C measured in accordance with JIS K-7120,
The airgel composite material has a 25% compressive load of 10 to 1000 kPa as measured in accordance with JIS K-6254,
An airgel composite material characterized by its use in thermoforming.

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