JPH03225182A - Heat insulating material for refrigerator - Google Patents

Abstract

PURPOSE:To maintain heat insulating property for a long period of time, permit the easy working of a complicated configuration and prevent the discharging of poisonous substances by waste disposal by a method wherein fluoride hydrocarbon, having a low modulus of rupture for ozone, is employed as a foaming agent while the foaming agent is retained in closed-cells, constituting a foaming body. CONSTITUTION:Heat insulating material, inserted between the bulkheads of a refrigerator, is foamed by one or two kinds or more of fluoride hydrocarbons, selected from monochlorodifluoroethane, difluoroethane, 2,2-dichloro-1,1,1- trifluoroethane, 1,1,1,2-tetrafluoroethane and 2-chloro-1,1,1-trifluoroethane. This heat insulating material can be formed of multi-cellular foamable particles having the base resin of amorphous vinylidene chloride resin, which is formed so as to have an arbitrary configuration by welding them in a mold by fusion tightly each other and constituted of an in-mold foaming form having the density of 20-100kg/m<2> and average diameter of bubbles of 50-120mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat insulating wall of a refrigerator. More specifically, the present invention relates to a heat insulating material for a refrigerator made of an in-mold vinylidene chloride resin foam molded product using a fluorinated hydrocarbon having a low ozone depletion coefficient as a foaming agent.

[Conventional technology]

Conventionally, glass wool, expanded polystyrene, rigid polyurethane foam, etc. have been used as insulation materials for refrigerators. In recent years, there has been a desire to improve the insulation properties of refrigerators in order to save electricity, so the insulation walls of refrigerator presses are
A rigid polyurethane foam made by mixing and foaming an isocyanate stock solution and a polyol stock solution is used;
Styrofoam molded products are often used as insulation materials between compartments in refrigerators or in areas that require complex shape processing, such as back roads.

In particular, for the former, an isocyanate stock solution, a polyol stock solution, and a blowing agent, trichlorofluoromethane (hereinafter referred to as Freon 11), are mixed in the gap between the outer steel plate that makes up the refrigerator pressure body and the styrene resin sheet on the internal wall of the refrigerator. Because it is injected and foamed, it adheres well to the steel plate and the resin sheet on the inner wall, providing structural strength.Furthermore, since it is in a sealed state between the sheet members, the urethane foam can maintain its characteristic low heat over a long period of time. Conductivity (usually 0.
013-0.015kCa, l! 7m -h -'C
) is maintained.

(Problem to be solved by the invention) However, if there are parts that act as flow path resistance between the inner and outer surfaces, a difference will occur in the growth rate of the foam, forming air pockets (voids), and the insulation effect will be reduced. or reduce the
When the foam insulation material is cooled, the air pocket becomes negative pressure, deforming the side wall material and reducing the product value.

Further, when foaming the urethane foam, foaming pressure is generated, so a molding jig that can withstand the pressure is required, and it cannot be used for foam molded products having complicated shapes.

Therefore, the thermal conductivity of the insulation material that requires a cold air circulation path in the refrigerator is approximately 0.03 kca, I! 7m -
Foamed polystyrene has been used because it is easy to shape and has poor insulation performance (h ℃).

Refrigerators have become larger in recent years, but due to housing conditions where space for storing refrigerators is limited, it is not possible to increase the size without limit, and it is necessary to increase the effective volume inside the refrigerator. I'm being sexually harassed. For this reason, it is expected that the volume of heat insulating materials used will be reduced.

Furthermore, rigid urethane foam has been developed using Freon 11 as an essential blowing agent, as described above. Recently, specified fluorocarbons are considered to be the cause of the destruction of the earth's ozone layer, and in 1989, the Montreal Protocol was enacted, with the aim of completely abolishing specified fluorocarbons. Currently, new alternative foaming agent formulations are being intensively researched, but there is no established technology yet.

[Means and effects for solving the problem] Under such circumstances, the present inventors previously disclosed Japanese Patent Application Laid-Open No. 63-170433,
JP-A-63-170434 and JP-A-63-1704
As shown in each publication No. 5, vinylidene chloride, N-substituted maleimide, which has excellent gas barrier properties that allow the blowing agent to remain in independent cells for a long period of time, and N-substituted maleimide, which can be copolymerized with these. We can industrially supply in-mold foam molded products that are made of amorphous vinylidene chloride-based resin containing one or more types of monomers, can be easily processed into any shape, have low thermal conductivity, and have excellent heat insulation performance. I took it as a thing.

However, even with the above-mentioned technology, there remains the problem of using a specific fluorocarbon as a foaming agent, which can destroy the earth's ozone layer, just like the urethane foam mentioned above.

Therefore, as a result of research, the present inventors have found that a fluorinated hydrocarbon, which has extremely poor affinity for the vinylidene chloride resin and has a low ozone depletion coefficient, is used as a blowing agent, and a foam formed using the blowing agent is constructed. We have discovered that it is possible to provide a refrigerator insulation material that maintains excellent insulation properties over a long period of time and can be easily processed into complex shapes by holding the inside of closed cells, which leads to the present invention.

That is, the above object of the present invention is to insert between the partition walls of a refrigerator,
Monochlorodifluoroethane, difluoroethane, 2,
2-dichloro1,1.1-trifluoroethane, 1,1
, 1.2-tetranoroloethane and 2-chloro-1,
A heat insulating material foamed with one or more fluorinated hydrocarbons selected from 1,1-trifluoroethane,
Porous foamed particles made of amorphous vinylidene chloride resin as the base resin can be tightly fused together in a mold and molded into any shape, with a density of 20 to 100 kg/m3, average cell size. This can be achieved by employing a heat insulating material for refrigerators characterized by being made of an in-mold foam molded product having a diameter of 50 to 120 μm.

Hereinafter, the content of the present invention will be explained in detail.

The main points of the present invention are: (1) Monochlorodifluoroethane (R-14
2b, 0.06), difluoroethane (R152a
, O), 2,2-dichloro1,1.1-trifluoroethane (R-123,0,02), 1,1,1.2-
Tetrafluoroethane (R-1348,0), 2-chloro-1,1,1-trifluoroethane (R-124゜0)
．． 02) etc. [The numbers in parentheses indicate the abbreviated name of each compound and the ozone depletion coefficient. ] or a mixture of two or more compounds selected from the following.

These compounds were approved by the United Nations Environment Program (UN) in September 1988.
EP) It is a low boiling point fluorinated hydrocarbon that has an ozone depletion coefficient of 0.1 or less based on the announcement, contains hydrogen atoms in the molecule, and has 2 or more carbon atoms.

(2) The foaming agent makes it possible to produce an amorphous vinylidene chloride resin in-mold foamed product having an average cell diameter of 50 to 120 μm and a density of 30 to 100 K'j/m3.

First, requirement (2) is fundamental to the present invention.

In general, the conditions for a blowing agent that can be used in in-mold foam moldings are (a) a compound that can be impregnated (dissolved) into the base resin, and (b) a compound that can be impregnated into the resin. An essential condition for a material that can be used for general purposes is that the compound does not easily volatilize and disappear at room temperature and atmospheric pressure.

However, it is difficult for fluorinated hydrocarbon compounds with low ozone depletion coefficients to satisfy the above condition (a) for the amorphous vinylidene chloride resin that is the base resin of the present invention, and even with these compounds, carbon For compounds whose number is less than 2, example (a)
Even if the above conditions were satisfied, the above condition (b) was not satisfied.

As a result of extensive studies, the present inventors have discovered that it is possible to simultaneously satisfy (a) and (b) above by using an appropriate impregnating aid when impregnating the base resin with a foaming agent. A difficult-to-impregnate foaming agent is impregnated into vinylidene chloride resin particles, allowing the foaming agent to be retained for a long period of time, and the impregnation aid used can be selectively volatilized and removed from the particles. .

Next, the requirements for (■) will be explained.

In general, in order to improve the insulation properties of foam insulation materials, it is necessary to ensure that the gas in the closed cells constituting the foam is a gas with low thermal conductivity, that is, fluorohydrocarbon, and that the expansion ratio of the foam is adjusted appropriately. It is well known that it is effective to make the bubbles finer in order to improve the heat insulation properties. These matters can be satisfied by making the above item (2) possible. That is, by using a fluorinated hydrocarbon as a blowing agent, which has poor affinity for vinylidene chloride resin as a base material and has an ozone depletion coefficient of 0.1 or less, it can be used as a heat insulating material during heat foaming. At a density of ~100 kg/m3, 50~1
It has now become possible to provide a foamed heat insulating material having an unprecedentedly uniform and fine average cell diameter of 20 μm.

Furthermore, when using a foam as a heat insulating material, selection of the density of the foam is important. FIG. 1 shows the relationship between the density and thermal conductivity of the vinylidene chloride resin in-mold foamed molded product of the present invention. As is clear from this figure, the density of the foam is 20
To! For those with a thermal conductivity of less than J/TrL3, the thermal conductivity of conventional styrene foam (=0.028kcaj/r
This is a region that is approximately equal to rt −h·”C) and increases rapidly as the density decreases.

Moreover, if it exceeds 100 kg/m3, although there is no sudden change, the weight of the resin used increases, which is economically disadvantageous. A foamed molded article having a preferable density range of 20 to 100 kg/m3 is preferable. More preferably, the bubble diameter is 90
~50 μm, finer and less change in thermal conductivity 3
It is better to choose foams with a density of 0 to 100 K'J/m3.

For example, if a foam with a density of aOKl/m3 is used,
The thermal conductivity is 2/3 that of conventional styrofoam, and when used as a heat insulating material, the required thickness is 2/3, and it can be applied to any shape that can significantly reduce the volume of heat insulating material used. Therefore, when the space volume is limited, it can be provided as the optimal material for increasing the effective volume.

As mentioned above, the blowing agents that can be used in the present invention are specifically:
For example, monochlorodifluoroethane (R-142b,
0.06>, difluoroethane (R-152a,
0), 2,2-dichloro1,1,1-trifluoroethane (R-123, 0,02>, 1,1,1,2-tetrafluoroethane (R-134a, 0), 2-[ 1
01,1,1-trifluoroethane (R-124,0,
02) [The numbers in parentheses indicate the abbreviated name of each compound and the ozone depletion coefficient]. Of course, these alone,
Alternatively, two or more types of compounds may be used in combination.

Among these foaming agents, R-142b, R-134a, R-124, etc. are preferred as they maintain long-term heat insulation performance, which is one of the objectives of the present invention, and have a low ozone depletion coefficient.

The foaming agent used in the present invention can be used in an amount of 4 to 40 parts by weight per 100 parts by weight of the resin particles, and the amount used is adjusted depending on the density of the intended foam.

Preferably, 6 to 20 parts by weight are used.

In order to easily impregnate the base resin with the above-mentioned foaming agent, which is difficult to impregnate, the base resin is swollen with the impregnation aid and then foamed. As a result of adopting a method of impregnating the resin with an impregnating agent and intensively investigating a method of selectively volatilizing only the impregnating agent impregnated into the resin, the present invention was completed.

That is, in the present invention, it has been discovered that the above object can be roughly understood by the magnitude of the dielectric constant of the solvent and the boiling point of the solvent. The impregnation aid needs to have a dielectric constant of 5.0 or more and a boiling point of 65° C. or less. An impregnation aid with a high boiling point tends to remain in the foamable resin particles of the product and tends to reduce the heat resistance of the foamed molded article obtained from the particles, and more preferably has a boiling point of less than 15°C.

Specifically, impregnation aids that can be used in the expandable resin particles of the present invention include, for example, acetone (ε-21,5, bp=56.2°C ),
Methanol (ε-31,2, bl)=64.5℃), methylene chloride (ε=9.1, bp=40℃), ethyl chloride (ε-6,3, bp=12.3℃), chloride Methyl (
ε=12.9. bp--23,8°C), difluoroethane (ε=10.02, bl)--25,0°C),
Monochlorodifluoromethane (ε=6.11. bp=
-40,8℃), dichloromonofluoromethane (ε=5
．． 34. bp=8.9°C).

Among these, those with a boiling point of 15 are more preferred as they are unlikely to remain in the expandable resin particles shipped as products.
Ethyl chloride, methyl chloride, difluoroethane, monochlorodifluoromethane, and dichloromonofluoromethane, which have a temperature below ℃, are preferable.

In addition, the values of dielectric constant and boiling point are: "Chemistry Handbook" Nihon Kagaku Complete Edition, August 20, 1971, 3rd printing.

Published by Marukubi [Solvent Pocket Book] Edited by the Organic Synthetic Chemistry Association, published November 25, 1962.

Published by Ohmsha ■ What is the amorphous vinylidene chloride resin used in the present invention?
For details, see JP-A-63-170433 and JP-A-63-1.
70434 and JP-A-63-170435@, it is composed of vinylidene chloride, N-substituted maleimide, and one or more monomers copolymerizable with these, and has a glass transition point of 85°C or higher. It is an amorphous vinylidene chloride copolymer.

N-substituted maleimide is selected as the main component to increase the glass transition point, such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N- -2-methylphenylmaleimide,
These include N-2-ethylphenylmaleimide, N-2-chlorophenylmaleimide, N-2-methoxyphenylmaleimide, N-2,6-dimethylphenylmaleimide, and one or more of these can be used. N-phenylmaleimide and N-2-chlorophenylmaleimide are preferred because they are easily available industrially, and N-phenylmaleimide is particularly preferred.

Vinylidene chloride and one or more vinyl monomers copolymerizable with the above N-substituted maleimide include vinyl chloride, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, acrylic acid, methacrylic acid, and methyl acrylate. , ethyl acrylate, butyl acrylate, methyl methacrylate, glycidyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, glycidyl methacrylate, etc., and one or more of these may be used. I can do it. Acrylonitrile, styrene, and methyl methacrylate are preferred because they tend to raise the glass transition point of the copolymer composition.

Although 7-acrylonitrile is preferable from the viewpoint of imparting flame retardancy, it is even more preferable to use a mixture of acrylonitrile and styrene because the thermoplasticity and elongation at high temperatures of the copolymer composition will increase.

The seven-mer composition of the amorphous multicomponent copolymer includes 30 mol% to 65 mol% vinylidene chloride, 1 mol% to 10 mol% N-substituted maleimide, and one or more types copolymerizable with these. It is preferable to select a composition range of 70% by mole to 70% by mole.

If the amount of nylidene chloride is less than 30 mol %, the flame retardance of the resulting foamed molded article will be insufficient, and if it exceeds 65 mol %, the impregnation of the foaming agent will be poor.

In addition, if the N-substituted maleimide content is less than 1 mol%, the glass transition point of the base resin will be low, resulting in poor dimensional stability when heated, and if it exceeds 10 mol%, the impregnation of the blowing agent will still occur. Sexuality becomes poor.

Further, as a crosslinking component, 0.1 mol % or less of one or more compounds having two double bonds in one molecule represented by the general formula (2) may be used.

[General formula■]

R1 represents -H or -CH3, R2 is 1-25,
n represents an integer of 2 to 3. ) or a phenylene group.

Compounds represented by the general formula (■) include divinylbenzene, 1,3-butylene glycol dimethacrylate, 1
．． 6-hexanethiol dimethacrylate, neopentyl glycol dimethacrylate, ethylene glycol dimethacrylate, other ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,6-hexanediol diacrylate,
They are neopentyl glycol diacrylate, ethylene glycol diacrylate, and propylene glycol diacrylate, and one or more of these can be used.

When foamed particles are obtained using non-quality vinylidene chloride resin particles crosslinked with these crosslinking agents, they are rich in closed cells, have good in-mold moldability, and have excellent compressive strength and thermal conductivity. A foamed molded article can be obtained in good yield.

The polymerization method in the present invention is known suspension polymerization, emulsion polymerization,
Various methods such as solution polymerization and bulk polymerization can be employed. As the polymerization initiator, known radical polymerization initiators can be used. The polymerization temperature and polymerization time can be appropriately selected in consideration of the radical polymerization initiator used, polymerization heat removal, yield, etc. As a method for separating and taking out the copolymer composition from the reaction solution, known methods such as coagulation, evaporation, filtration, and drying can be employed. If necessary, additives such as plasticizers, heat stabilizers, light stabilizers, antioxidants, slip agents, and colorants may be added to the copolymer composition by known methods.

In addition, the amorphous polymer as used in the present invention refers to a polymer that does not exhibit an endothermic peak due to melting of a crystalline component when measured using a differential scanning calorimeter (DSC), and furthermore, an amorphous polymer that does not exhibit an endothermic peak due to melting of a crystalline component when measured using a differential scanning calorimeter (DSC), and furthermore, an amorphous polymer that does not exhibit an endothermic peak based on melting of a crystalline component when measured using a differential scanning calorimeter (DSC), or a polymer that does not exhibit a diffraction peak based on a crystalline component when measured using an X-ray diffraction method. Generally, the copolymer becomes crystalline in a region where vinylidene chloride is more than 85 mol %, but these crystalline copolymers are excluded from the present invention.

As a method for incorporating the above-mentioned blowing agent into the base resin,
For example, in a pressure vessel such as an autoclave, under heating and pressure if necessary, the resin particles are mixed with an impregnating agent and a blowing agent having a dielectric constant of 5.0 or more and a boiling point of 65°C or less to form a gaseous,
Alternatively, there is a gas phase or liquid phase impregnation method in which resin particles are impregnated in a liquid state, and an underwater suspension impregnation method in which resin particles are suspended in water and impregnated using a combination of an impregnation aid and a foaming agent. Of course, the resin particles may be impregnated with the impregnation aid in advance and then impregnated with the foaming agent, or the resin particles may be impregnated with both in coexistence.

As a foaming method for obtaining the multicellular expanded particles of the present invention, for example, a known method may be used in which resin particles containing a foaming agent are heated and foamed with a heating medium such as steam, hot water, or hot air. can.

As heating conditions for obtaining multicellular expanded particles, heating at a temperature equal to or higher than the glass transition point (Tfj) of the base resin for a predetermined time is appropriately selected depending on the desired magnification. Generally, a temperature range of 100 to 130'C and a heating time of 5 to 180 seconds are sufficient.

The in-mold foam molded article of the present invention is obtained by applying a known in-mold molding method to the multicellular foam particles obtained as described above. That is, a mold with many small holes that can be closed but cannot be sealed is filled with porous foam particles, and the foam is expanded by heating with a fluid such as steam through the small holes from outside the mold wall. After filling the gaps between the particles and fusing them, this is rapidly cooled to form a molded body. Through this manufacturing method, a large number of multicellular foamed particles whose base resin is heat deformation-resistant vinylidene chloride resin are fused together by closely contacting the outer surfaces of adjacent particles to form an integrated foamed molded product. The structure is as follows. Specifically, the heating conditions can be almost the same as those for the well-known in-mold molding method for foamed polystyrene particles, and are appropriately set depending on the shape and wall thickness of the molded product. Generally, mold heating (OKg/ai-G steam), while heating (0,1~
0.5 'j/ci-G water vapor), and double-sided heating (0.5
,7 to 2.0! An integral molded body is obtained by the process of (i/ci-G water vapor) and the process of cooling the mold with cold water. The density of these foams can be changed depending on the requirements of each application, since the mechanical strength required varies depending on the application.

〔Effect of the invention〕

The vinylidene chloride-based resin in-mold foamed molded product used in the present invention can be manufactured without using specific fluorocarbon compounds that are subject to regulation by the Montreal Protocol when manufacturing the expandable particles that are the raw material. In addition, in the process of pre-foaming the expandable particles and subjecting them to in-mold molding, no substances that destroy the ozone layer are released into the atmosphere, and the molded products do not release any harmful substances during disposal. There is no release.

Furthermore, the foamed molded product has excellent flame retardancy, oil and chemical resistance, gas barrier properties, mechanical strength, heat resistance, and heat insulation performance, and can be applied to a wide range of uses.

Among the commercially available insulation foams, those that do not use specified fluorocarbons have high thermal conductivity but have slightly inferior insulation performance, while those that have low thermal conductivity and excellent insulation performance must use specified fluorocarbons. This is an unprofitable situation.

In view of the current situation, the present invention provides a heat insulating material for a refrigerator using a foam that has low thermal conductivity, does not cause environmental pollution, and can be formed into any shape and has excellent heat insulation performance. .

Because of its low thermal conductivity, compared to conventional polystyrene foam, etc., if you expect the same insulation performance, you only need to use about 2/3 the thickness. If used as a container, the effective volume inside the refrigerator can be increased.

In addition, the molded article of the present invention exhibits an extremely low thermal conductivity value immediately after molding, and exhibits a low thermal conductivity value of 0.019 kcal/rrt −h −′C as a stable value after sufficient aging. It is something. Therefore, if it is used in a sealed state with a sheet member such as steel or resin immediately after molding, it can also be used as a high-performance heat insulating material.

As described above, the present invention is a significant invention as it provides a heat insulating material, particularly a heat insulating material for refrigerators, which is extremely useful both industrially and from the standpoint of environmental protection.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to examples, but the present invention is not limited by these examples.

The evaluation method used in the present invention is as follows.

○ Foam density: Based on JIS-6767.

○ Expansion ratio: 2 Base resin density divided by foam density.

○ Closed cell ratio: Based on ASTt4 D-2856.

○ Thermal conductivity: Based on ASTHC-518.

○ Average cell diameter Cell diameter in arbitrary cross section of binary foam 5~
Measurements were made at 10 points, and the sieving average value was used.

O glass transition point: Measure the exothermic or endothermic differential curve from the differential calorific value vs. temperature function using a differential scanning calorimeter (DSC) according to ASTHD-3418-75.

Example 1. Comparative Example 2 Vinylidene chloride (50% by weight) obtained by suspension polymerization method
), N-7 enylmaleimide (7% by weight), acrylonitrile (20% by weight), and styrene (23% by weight).
．． Bridged with 07% by weight of 1,6-hexanediol diacrylate! The treated copolymer particles were subjected to experiments.

The resin had a specific gravity of 1.45 and a glass transition point of 97°C.

The average particle diameter is 0.5. 100 parts by weight of the resin particles are placed in an autoclave, the autoclave is sealed, and the autoclave is vacuum degassed.

Next, 200 parts by weight of monochlorodifluoroethane (R-142b) having an ozone depletion coefficient of 0.06 and methyl chloride as an impregnation aid are injected in the proportions shown in Table 1. Then, after being kept under stirring at 60° C. for 20 hours, the mixture is cooled and returned to normal pressure, and the resin particles are taken out.

The particles were impregnated with a blowing agent, and Table 1 shows the amount of blowing agent retained in the particles after being left at room temperature and atmospheric pressure for one month (30 days) immediately after production.

Further, the expandable particles obtained from each of the above formulations were aged for about one month and then heated and foamed with steam at 0.3 Kl/cut-G for 45 seconds to obtain pre-expanded particles. Table 1 shows the expansion ratio.

As is clear from Table 1, when no impregnation aid is used, the foaming agent R-142b is hardly contained in the resin, and the foaming properties are poor even when heated, but It can be seen that the content of the impregnating aid increases dramatically, and expandable particles with excellent expandability can be obtained.

Next, the pre-expanded particles with an expansion ratio of 23 times in Experiment Nfi2 were aged at room temperature for 24 hours, and heated with steam at a rate of 1/cri-G to approximately 1.0 in an in-mold foam molding machine for expanded polystyrene. Molded, thickness 25#ll, 30011111
The density in all directions is 40! j/TrL3, average bubble diameter is 75μ
A foamed molded article of m was obtained. The thermal conductivity of this molded body is
Immediately after manufacturing, 0.0145kca1/m −h −”
C, it became stable after one month of ripening, and maintained a low value of 0.019 kcaj/m −h −′C even after about one year.

Example 2. Comparative example 2 Expandable particles were obtained in the same manner as Experiment NQ2 of Example 1.

The expandable particles were heated with steam under the conditions shown in Table 2.
The mixture was heated and foamed for 0 seconds to obtain pre-expanded particles. Roughly,
Using the pre-expanded particles, a foam molded article was obtained in the same manner as in Example 1.

Table 2 shows the density, average cell diameter, and thermal conductivity of the foam molded product obtained. The thermal conductivity in the table shows the measured value after the obtained molded product was aged at room temperature for about one month.

For comparison, the same experiment was conducted using commercially available expanded polystyrene (manufactured by Mitsubishi Yuka Pardish Co., Ltd.), and the results are also shown in the Experiment No. 013 column of Table 2.

(Margin below) 4,

[Brief explanation of drawings]

FIG. 1 is a correlation diagram between density and thermal conductivity of the foamed molded product of the present invention.

Claims (1)

[Claims] 1. Inserted between the partition walls of the refrigerator, monochlorodifluoroethane, difluoroethane, 2,2-dichloro1,1,
Foamed with one or more fluorinated hydrocarbons selected from 1-trifluoroethane, 1,1,1,2-tetrafluoroethane, and 2-chloro-1,1,1-trifluoroethane It is a heat insulating material, and can be molded into any shape by tightly fusion of foamed particles made of amorphous vinylidene chloride resin as the base resin, and has a density of 20.
~100kg/m^3, average bubble diameter 50~120μm
A heat insulating material for a refrigerator comprising an in-mold foam molded article.