JPS6228242A - Packaging material for heat-insulating material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Mi. Part 1 The present invention has resistance to chlorofluorohydrocarbon gases (refrigeration gas) such as trichlorofluoromethane and dichlorodifluoromethane, and is particularly suitable for manufacturing vacuum insulation boards. The present invention relates to a packaging material for a heat insulating material that is suitably used.

``l double i'' Conventionally, foamed perlite has been generally used as an insulating material for keeping heat and cold in refrigerators and freezers, as seen in Japanese Patent Publications No. 58-50392 and 58-50394@ A heat insulating board is used in which a bag made of plastic laminated film is filled with inorganic powder (insulating material), vacuum degassed, and sealed. Figure 1 shows an example of this type of heat insulating board, where 1 is a plastic MIIW.
This bag is made of film, and the inside of this bag 1 is filled with a heat insulating material 2. When this heat insulating board is used to keep a refrigerator cool, for example, the heat insulating board 1 is inserted into the partition wall 3.3 of the refrigerator, etc., as shown in FIG. 2, and the distance W! A urethane resin 4 is filled between 3° and 3° and foamed with a chlorofluorohydrocarbon gas added to the urethane resin in advance.

In this case, as the packaging material for the heat insulating material constituting the bag 1, polyethylene terephthalate is conventionally used on one side of the metal layer 5 (the side that forms the surface of the bag) formed of aluminum foil, aluminum vapor-deposited film, etc. Plastic outer layer 6 formed of film, polyamide film, etc.
In addition, a plastic inner layer 7 made of low-density polyethylene is laminated on the other side of the metal layer 5. When forming the bag 1 from this packaging material, for example, two sheets are used. The bag 1 was formed by stacking plastic laminated films so that their plastic inner surfaces 1@7.7 faced each other and heat-sealing the ends 8.8.

However, in conventional packaging materials of this type, low-density polyethylene is used as the innermost layer (heat-sealing layer) to ensure heat-sealability, but low-density polyethylene is chlorofluorocarbonized. Because it is easily attacked by hydrogen gas, if a bag with low-density polyethylene is used as a heat-sealing layer for heat insulation as shown in Figure 2, there will be moisture on the end surface of the bag. The low-density polyethylene that is used in the bag is attacked by the residual chlorofluorohydrocarbon gas, and the chlorofluorohydrocarbon gas enters the inside of the bag, lowering the vacuum level of the bag and reducing its insulation performance. Problems arise, such as the low-density polyethylene turning into powder and no longer functioning as a bag. For this reason, we developed a heat-sealing layer [the first method using low-density polyethylene as a packaging material].
The heat insulating board as shown in the figure could not maintain its cold retention properties for a long time in a chlorofluorohydrocarbon gas atmosphere.

In view of the above-mentioned circumstances, the inventors of the present invention have submitted a patent application filed in 1983-
No. 156311 is a packaging material that uses a film made by mixing linear low-density polyethylene or polyisobutylene with high-density polyethylene as the thermal adhesive layer that constitutes the innermost layer of these packaging bags for insulation materials. We have found that this material has good resistance to chlorofluorohydrocarbon gases, and have filed a patent application based on this finding. However, in the case of durable materials such as refrigerators, use +! IJ I
Because of the considerable length of time, packaging materials that are better resistant to chlorofluorohydrocarbon gases are desired.

The present invention has been made in response to the above-mentioned needs, and an object of the present invention is to provide durable heat-sealing without reducing the heat-sealing performance that should naturally be provided as a heat-adhesive resin layer constituting the innermost layer of a packaging bag. An object of the present invention is to provide a packaging material having good chlorofluorohydrocarbon gas properties.

To solve the problems: In order to achieve the above object, the present inventors have conducted intensive research and have found that the results can be obtained by using a mixed film of polyester and polyamide as the innermost layer of the packaging material. The present inventors have discovered that the permeation of chlorofluorohydrocarbon gas can be dramatically reduced without reducing the thermal adhesion performance of packaging bags, and have completed the present invention.

According to the present invention, by using the film obtained by mixing polyester with polyamide as the material constituting the innermost layer of the packaging material for vacuum insulation material, the packaging bag made of the packaging material of the present invention can be produced. It has excellent resistance to chlorofluorohydrocarbon gases and good heat-sealability, but it also overcomes the drawbacks of high-density polyethylene, such as poor drop strength and impact strength at low temperatures, and is prone to pinholes when handled at low temperatures. These drawbacks can be overcome, and for this reason, it is suitable for use in manufacturing vacuum insulation boards.

The present invention will be explained in detail below.

The packaging material for a heat insulating packaging bag according to the present invention is a packaging material using a film obtained by mixing polyester with polyamide as the innermost layer.

Here, the polyester that can be used in the present invention preferably has an average molecular weight of 20,000 to 40,000, <G;
A polyester obtained by cocondensation polymerization of at least one acid component and at least one alcohol component of 125,000 to 35,000 is preferred. In this case, polyesters in which the acid component is an aromatic dicarboxylic acid such as phthalic acid, terephthalic acid, or isophthalic acid are preferable. Cole, ternary cocondensation polymerization of terephthalic acid, isophthalic acid, and 1,4-butanediol, terephthalic acid, isophthalic acid, and polypropylene glycol, terephthalic acid, isophthalic acid, and 1,4-dicyclohexanedimetatool. Copolyesters obtained by cocondensation polymerization of brephthalic acid, isophthalic acid, ethylene glycol, and polypropylene glycol can be effectively used, but among them, it is preferable to use polyethylene terephthalate.

Polyamides that can be mixed with the above-mentioned polyester include nylon 6, nylon 101, and nylon 1, each having an average molecular weight of 5,000 to 30,000, preferably 8,000 to 15,000.
1. Nylon 12, Nylon 6.6, Nylon 6.10
, nylon 6-6.6 copolymer, etc. can be suitably used, but it is most suitable to use nylon 6 and nylon 6-6.6 copolymer for carrying out the present invention.

In this case, the mixing ratio of polyester and polyamide is
5 to 3 polyamides per 100 layers of polyester
It is desirable to set it as 0 river part, especially 10-20 heavy water part. If the ratio of polyamide is less than 5 heavy chain parts to 100111 parts of polyester, heat sealability, impact strength, and drop strength will decrease;
If the amount is exceeded, the resistance to chlorofluorohydrocarbon gas may deteriorate. The film obtained by mixing the polyester and polyamide is preferably an unstretched film, and its thickness is appropriately selected depending on the required dimensions of the heat insulating board, the type of inorganic powder contained in the product, and the weight of the inorganic powder. However, it is usually 10 to 150 μm, especially 20 to 100 μm.
It is preferable to set it to 1.

The packaging material of the present invention is not limited in its structure, except that the mixed film of polyester and polyamide is used as the innermost layer, and materials used as packaging materials for ordinary heat insulating materials can be used. However, in this case, the surface material laminated on the mixed film of polyester and polyamide is not particularly limited, but since the packaging bag is used in a vacuum, it must be non-breathable and gas-impermeable. Stretched polyester film, stretched nylon film, stretched polypropylene film, or films with metals such as aluminum or metals such as aluminum foil, etc. to reflect heat. A composite film made by laminating 11 foils or suitably laminating them can be effectively used. Further, if necessary, a gold B foil layer or a metal film-forming plastic film layer may be interposed as an intermediate layer. As a method for laminating and combining the materials, a known extrusion method, a dry lamination method using an adhesive, or the like can be used alone or in combination.

In addition, when aluminum foil is used in the composition of the packaging material of the present invention, the packaging is such that the aluminum foil is removed from the exposed aluminum foil at the cross section of the thermally bonded portion at the edge of the packaging bag in order to avoid conduction of heat from the aluminum foil. It is more preferable to form a bag.

As described above, the packaging material using the film obtained from the polyester/polyamide mixture as the innermost layer according to the present invention has excellent resistance to chlorofluorohydrocarbon gas, It can be effectively used in a 0-fluorohydrocarbon gas atmosphere, and is suitably used, for example, as a packaging material for making a heat insulating board as shown in FIG. 1 used for cold insulation in refrigerators and the like.

That is, in FIG. 1, when the packaging material according to the present invention is used as the laminated material constituting the innermost layer of the packaging bag, it has good heat sealing properties, is easy to manufacture the packaging bag, and has good resistance to chlorination as described above. 0-fluorohydrocarbon gas properties are also good, so even if a heat insulating board made of this packaging material is placed inside a foamed resin foamed with fluorofluorohydrocarbon gas as shown in Figure 2, no chlorofluorohydrocarbons will be released. It will not be attacked by gas, and chlorofluorohydrocarbon gas will not enter the inside of the packaging bag and reduce the heat insulation performance that it should originally have. In addition, the packaging material of the present invention has high drop strength and impact resistance at low temperatures, and also has good pinhole resistance, making it an extremely excellent material for manufacturing heat insulating boards by Kawasaki for cold insulation such as refrigerators. be.

Examples and comparative examples are shown below to specifically illustrate the present invention.
The invention is not limited to the following examples.

(Example, Comparative Example) As a packaging material, the outer layer is biaxially oriented polyester with a thickness of 12 μm, the inner layer is made of aluminum with a thickness of 9 μm, and the innermost layer is made of polyester/polyamide with a thickness of 60 μm at a mixing ratio of 1.
Examples 1 and 2 were prepared by sequentially laminating mixed films of 00:20 (weight ratio) using an isocyanate adhesive to produce packaging materials of the present invention.

For comparison, the innermost layer was a mixed film of 60 μm thick low density polyethylene, 60 μm thick high density polyethylene mixed with orthogonal low density polyethylene at a weight ratio of 20%, and 60 μm thick high density polyethylene mixed with polyisobutylene. Packaged feeds with the same composition except that films containing 5% of protein and T11 were used (Comparative Example 1.2.3)
) was manufactured.

In this case, the polyester has an average molecular weight of about 35
,000 of terephthalic acid, isophthalic acid, and ethylene glycol in a ratio of 10:1:11. In Example 2, a copolymerized nylon obtained by copolymerizing nylon 6 and nylon 6.6 with an average molecular weight of 115,000 at a weight ratio of 1=1 was used.

From the packaging materials of these Examples and Comparative Examples, 1010X1
A sample of No. 0 was taken and immersed in a trichloromonofluoromethane (Freon 11) gas liquid at a temperature of 60° C. for 7 days to examine the absorption of trichloromonofluoromethane gas into the innermost layer film.

In addition, a sample of the same size as above was stacked face-to-face at 13 degrees Celsius.
Heat sealing was performed at a temperature of 0 degrees for 1 second by applying a pressure of about 2 ka/cWl, and the heat sealing strength was measured according to JIS-Z-1526. The results are shown in Table 1.

Table 1 Furthermore, the absorption Wffi of trichloromonofluoromethane gas was measured when the packaging materials of the above Examples and Comparative Examples were immersed in trichloromonofluoromethane gas for 6 hours for 14 days and 28 days. As a result, Example 1,
The packaging material according to No. 2 adsorbed less trichloromonofluoromethane gas than the comparative example, and was able to withstand use as a packaging bag for insulation materials.

Furthermore, a packaging material (Comparative Example 4.5) was produced using the above-mentioned polyester and polyamide in which 50 μm thick films with a mixing ratio of 100:1 and 100:40 were attached to the innermost layer using an isocyanate adhesive. As described above, the thermal adhesive strength and the adsorption amount of trichloromonofluoromethane gas immersion were compared with those of Example 1 described above. The results are shown in Table 3.

In Comparative Example 4 of Table 3, film breakage occurred during the film forming process, making it difficult to form the film.

In view of these results, the packaging material using the film of Example 1.2, which is a mixture of the polyester and nylon of the present invention, can be used as a packaging bag for insulation material for a long period of time in a resin foamed with lyrofluorohydrocarbon gas. The device was found to be fully functional.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of a heat insulating board, and Fig. 2 is an example of construction of the same heat insulating board. 1 is a sectional view. 1...Wrap\i bag, 2...Insulation board, 4...Urethane resin.

Claims (1)

[Scope of Claims] 1. A packaging material for manufacturing a packaging bag that covers a heat insulating material, wherein the layer constituting the innermost layer of the packaging material is made of a mixed resin film of polyester and polyamide. A packaging material for insulation materials characterized by: 2. The packaging material according to claim 1, wherein the mixing ratio of polyester and polyamide is 5 to 30 parts by weight of polyamide to 100 parts by weight of polyester.