JP2018053949A - Sheathing material for vacuum heat insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheathing material for a vacuum heat insulation material that can prevent the vacuum heat insulation material from cracking or having a pinhole formed including its corner parts without requiring any troublesome drying process.SOLUTION: A sheathing material 1 for a vacuum heat insulation material is constituted by stacking a base material film 11, a gas barrier layer 12 and a sealant layer 13 in order from outside, and as the base material film 11, a film is used which has a single-layer structure or multi-layer structure including a two-axially drawn film (two-axially drawn PBT-based film) containing 50 wt.% or more of polybutylene telephthalate. The two-axially drawn PBT-based film has small water absorptivity and can prevent a crack and a pinhole from being formed even at corner parts of the vacuum heat insulation materials.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vacuum heat insulating material exterior material for a vacuum heat insulating material attached to a refrigerator, a low temperature container, an outer wall material of a house, or the like.

  Various heat insulating materials have been conventionally used for refrigerators, low temperature containers, and outer wall materials of residences. In particular, as a heat insulating material having excellent heat insulating performance, the core material 2 is enclosed in the exterior material 1 and the interior is enclosed. A vacuum heat insulating material A is used that is sealed by evacuation and heat sealing the exterior material 1 (see FIG. 2).

  This exterior material 1 needs to be excellent in gas barrier properties in order to prevent gas from entering from the outside and keep the inside in a vacuum state for a long time. Therefore, conventionally, in order to provide a high gas barrier property, a laminated film including a metal aluminum foil having a thickness of about 7 to 15 μm or a vapor deposited film on which a metal or an inorganic material is deposited has been mainly used as the gas barrier layer of the exterior material 1.

  Thus, since the heat insulating material A is configured by vacuum packaging the core material 2 with the exterior material 1, the exterior material 1 is deformed along the outer shape of the core material 2. For this reason, as shown in FIG. 2, a lot of fine irregularities are formed in the exterior material 1 and bent by the irregularities. The metal aluminum foil and the vapor deposition layer in the exterior material 1 have a problem that cracks and pinholes are generated due to this fine bending, and the gas barrier property is remarkably deteriorated. It was difficult to keep it in a vacuum.

  Attempts have been made to reduce the occurrence of cracks and pinholes and maintain the vacuum state inside the exterior material 1 for a long period of time. For example, the layer structure is, in order from the outside, a first stretched nylon film, a second stretched nylon film, a gas barrier layer made of a metal foil or the like, a heat-welded layer, and the first and second stretched nylon films between There was an exterior material 1 provided with an adhesive layer (Patent Document 1). Since these stretched nylon films are tough, cracks and pinholes are not generated even by the fine bending as described above.

  However, even if these two stretched nylon films are used, the stretched nylon films are stretched at the corners x of the vacuum heat insulating material A, and cracks and pinholes are generated in the aluminum foil and the deposited layer. As a result, it is difficult to keep the interior of the exterior material 1 in a vacuum state. Further, these stretched nylon films are easy to absorb moisture, and therefore, a complicated drying process is required before the vacuum heat insulating material A is manufactured.

Japanese Patent No. 3482408

  Therefore, the present invention provides an exterior material for a vacuum heat insulating material that does not require a complicated drying step, and that can prevent the occurrence of cracks and pinholes including the corner portion x of the vacuum heat insulating material A. With the goal.

That is, the invention according to claim 1 is an exterior material for a vacuum heat insulating material configured by laminating a base film, a gas barrier layer, and a sealant layer in order from the outside.
For the vacuum heat insulating material, wherein the base film has a single layer structure or a multilayer structure, and a biaxially stretched film containing 50% by weight or more of polybutylene terephthalate is included in the layer structure. It is an exterior material.

  Next, invention of Claim 2 is the exterior material for vacuum heat insulating materials of Claim 1 in which the said biaxially stretched film contains a polyethylene terephthalate.

  Next, the invention described in claim 3 is the exterior material for a vacuum heat insulating material according to claim 2, wherein the biaxially stretched film has a polyethylene terephthalate content of 1 to 50% by weight.

  Next, the invention according to claim 4 is characterized in that both the tensile strength in the MD direction and the tensile strength in the TD direction of the outermost layer of the biaxially stretched film are 150 MPa or more. It is the exterior material for vacuum heat insulating materials in any one of 1-3.

  Next, the invention according to claim 5 is characterized in that the biaxially stretched film is arranged in the outermost layer of the base film, and the exterior for vacuum heat insulating material according to any one of claims 1 to 4 It is a material.

  Next, the invention according to claim 6 is characterized in that the gas barrier layer is made of any one of a metal foil, a resin film deposited with a metal or an inorganic oxide. It is the exterior material for vacuum heat insulating materials.

  Polybutylene terephthalate is a resin with low water absorption. Moreover, as can be seen from the fact that the gelboflex test shows good properties, it has high resistance to local forces and elongation. For this reason, as can be seen from the examples to be described later, when the core material is vacuum-packed using the exterior material according to the present invention, the biaxial material including the corner portion and including 50% by weight or more of this polybutylene terephthalate is included. The stretched film is hardly cracked or pinholed. For this reason, the exterior material which concerns on this invention can be used with a vacuum heat insulating material, without requiring a complicated drying process, and can prevent generation | occurrence | production of a crack and a pinhole.

FIG. 1A and FIG. 1B are cross-sectional explanatory views showing examples of the exterior material of the present invention. FIG. 2 relates to an example of a heat insulating material, FIG. 2 (a) is a perspective explanatory view thereof, and FIG. 2 (b) is a cross sectional explanatory view thereof.

  The exterior material which concerns on this invention is used when vacuum-packing a core material and manufacturing a heat insulating material, and comprises the outer surface of the completed vacuum heat insulating material.

  This exterior material is formed by laminating a base film, a gas barrier layer, and a sealant layer in order from the outside. The base film may have a single layer structure composed of a single film, or may have a multilayer structure in which a plurality of films are laminated. When the base film has a single layer structure, the base film needs to be composed of a biaxially stretched film (biaxially stretched PBT film) containing 50% by weight or more of polybutylene terephthalate (PBT). . Moreover, even when the base film has a multilayer structure, at least one of the plurality of films constituting the base film needs to be a biaxially stretched PBT film. In addition, the film which provided the ink film and the vacuum evaporation film | membrane can be used for this biaxial stretching PBT type | system | group film.

  As described above, since the vacuum heat insulating material A is configured by sealing the core material by enclosing the core material in the exterior material and heat-sealing the exterior material, the biaxially stretched PBT film is composed of the outermost layer of the exterior material, That is, it is desirable to be located in the outermost layer of the substrate film. Since the biaxially stretched PBT film is biaxially stretched, it has heat resistance and toughness. By disposing the biaxially stretched PBT film in the outermost layer, the exterior material 1 becomes a heat seal bar during heat sealing. It is because it can prevent adhering to a heat seal roll etc.

  When the base film has a multilayer structure, the other film that can be used together with the biaxially stretched PBT film may be any film, but a biaxially stretched polyethylene terephthalate film (biaxially stretched PET film) can be suitably used. Alternatively, it may be a film having a multilayer structure in which a plurality of biaxially stretched PBT films are laminated.

  When the example of the exterior material which uses such a base film is shown, what has a layer structure as shown to Fig.1 (a)-FIG.1 (b) can be illustrated. FIG. 1A shows a base film 11 made of a single film, and this film is made of a biaxially stretched PBT film 11a. As described above, the biaxially stretched PBT film 11a provided with a vacuum deposited film or the like can be used as the biaxially stretched PBT film 11a. And this exterior material 1 is comprised by laminating | stacking the gas barrier layer 12 and the sealant layer 13 in this order on one surface of the base film 11 (11a).

  Next, FIG.1 (b) makes the base film 11 into 2 layer structure. Of the two films constituting the substrate film 11, the film constituting the outermost surface is constituted by a biaxially stretched PBT film 11a. The inner film (inner film) 11b is composed of a biaxially stretched PET film or a biaxially stretched PBT film. As the biaxially stretched PBT film 11a and the inner film 11b, it is also possible to use the film provided with a vacuum deposited film or the like. And also in this exterior material 1, the gas barrier layer 12 and the sealant layer 13 are laminated | stacked in this order on one surface of the base film 11 (11a).

  By the way, the PBT film is generally difficult to be biaxially stretched due to the influence of its high crystallization speed. Therefore, biaxial stretching can be achieved by blending PBT with PBT and suppressing the crystallization speed. As the blending amount of PET is increased, the effect of suppressing the crystallization rate is improved, but the flexibility of the film is lost. For this reason, the blending amount of PET is desirably 1 to 50% by weight. When the PET content is less than 1% by weight, the effect of suppressing the crystallization rate is insufficient and biaxial stretching is difficult. On the other hand, if it exceeds 50% by weight, the flexibility of the biaxially stretched PBT-based film 11a is lost. Therefore, when the core material is vacuum packaged using the exterior material 1 of the present invention, a pinhole or the like is generated. There is.

  In addition to PET, this biaxially stretched PBT film 11a includes a lubricant, an anti-blocking agent, an inorganic extender, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer, a colorant, a crystal Additives such as crystallization inhibitors and crystallization accelerators can be blended, but even when these additives are blended, the content of PBT needs to be 50% by weight or more. When the content of PBT is less than 50% by weight, pinholes or the like may occur when the core material is vacuum packaged using the exterior material 1 of the present invention.

  Further, in order to prevent the occurrence of pinholes or the like during vacuum packaging in this way, the tensile strength in the MD direction and the tensile strength in the TD direction of the biaxially stretched PBT film 11a are both 150 MPa or more. It is desirable.

  This biaxially stretched PBT-based film 11a can be produced by both the simultaneous biaxial stretching method and the sequential biaxial stretching method. Examples of the simultaneous biaxial stretching method include a tubular method and a tenter method. The draw ratio is preferably in the range of 2.7 to 4.5 times in each of the MD direction and the TD direction. A tensile strength in the MD direction and a tensile force in the TD direction are obtained by biaxially stretching an unstretched PBT film having a tensile strength of 100 MPa or less in a range of 2.7 to 4.5 times in the MD and TD direction. A film having a strength of 150 MPa or more can be produced.

  Next, the thickness of the biaxially stretched PBT film 11a is desirably 10 to 100 μm. If it is less than 10 μm, its toughness is insufficient. Moreover, it is not necessary to be 100 micrometers or more, and a film thicker than this leads to a cost increase.

  As described above, the biaxially stretched PBT-based film 11a can be used with a vacuum vapor deposition film provided on the surface thereof. As the vacuum vapor deposition film, vapor deposition of aluminum, aluminum oxide, silicon oxide or the like is possible. A membrane can be illustrated. As described above, since the biaxially stretched PBT film hardly absorbs moisture, it has excellent dimensional stability in the vapor deposition process.

  Next, the gas barrier layer 12 has a function of preventing outside air from entering the inside of the vacuum heat insulating material A. As this gas barrier layer 12, the resin film which vapor-deposited metal foil, the metal, or the inorganic oxide can be used, for example. A typical example of the metal foil is an aluminum foil. Examples of the metal or inorganic oxide deposited on the resin film include aluminum, aluminum oxide, and silicon oxide. Although the resin film used as a vapor deposition base material may be an arbitrary material, an ethylene-vinyl alcohol copolymer film (EVOH film) can be preferably used. Although the EVOH film itself has an oxygen barrier property, the oxygen barrier property is lowered by moisture. By providing a metal vapor deposition film or an inorganic oxide vapor deposition film on the EVOH film, it is possible to prevent deterioration of the EVOH film due to moisture and further improve the oxygen barrier property.

  Next, although the sealant layer 13 can use a sealant resin having a melting point of 80 to 300 ° C., since the core material is vacuum-packed, a layer that does not generate outgas under vacuum is preferable. For this reason, a slip agent and a sealant resin with low low molecular weight components are desirable. The compounding amount of the slip agent is desirably in the range of 500 to 4000 ppm.

  Examples of such a sealant resin include polyolefin resins such as low density polyethylene, medium density polyethylene, linear low density polyethylene, and polypropylene. It is also possible to use a fluorine-based sealant resin.

  And these base film 11, gas barrier layer 12, and sealant layer 13 can be laminated and integrated by dry laminating using a publicly known urethane adhesive. Even when the base film 11 has a multilayer structure, the films constituting the base film 11 can be laminated and integrated by dry lamination.

Example 1
A biaxially stretched PBT film 11 a having a single layer structure was used as the base film 11. This biaxially stretched PBT film 11a is a biaxially stretched PBT mixed with PET.
The BT content is 50% by weight or more, and the PET content is 30% by weight or less. The thickness is 15 μm, the tensile strength in the MD direction is 240 MPa, and the tensile strength in the TD direction is 230 MPa.

  As the gas barrier layer 12, an 8021 aluminum foil having a thickness of 7 μm was used.

  As the sealant layer 13, a 50 μm-thick linear low-density polyethylene film (manufactured by Tamapoly Co., Ltd .; SE620N) was used.

  Then, the base material 11, the gas barrier layer 12, and the sealant layer 13 were integrated by dry lamination to produce the exterior material 1 of Example 1.

(Example 2)
A film having a two-layer structure was used as the base film 1.

  Of the two films constituting the base film 1, the film constituting the outermost layer of the packaging material 1 is a biaxially stretched PBT film 11 a. This biaxially stretched PBT-based film 11a is obtained by mixing PBT with PBT and biaxially stretching, and has a PBT content of 50% by weight or more and a PET content of 30% by weight or less. The thickness is 15 μm, the tensile strength in the MD direction is 240 MPa, and the tensile strength in the T direction is 230 MPa.

  Of the two films constituting the base film 1, the other film (inner film) 11b is a biaxially stretched PET film provided with a silicon oxide vapor-deposited film (manufactured by Toppan Printing Co., Ltd .: GL-RD). The thickness is 12 μm.

  Next, as the gas barrier layer 12, an EVOH film (manufactured by Kuraray Co., Ltd .: TM-XL) provided with an aluminum vapor deposition film was used. The thickness is 15 μm.

  As the sealant layer 13, a linear low density polyethylene film (Tamapoly Co., Ltd .; SE620N) having a thickness of 50 μm was used as in Example 1.

  Then, the biaxially stretched PBT film 11a, the inner film 11b, the gas barrier layer 12, and the sealant layer 13 were integrated by dry lamination to produce the exterior material 1 of Example 2.

(Example 3)
As the base film 1, a film having a single layer structure made of a biaxially stretched PBT film 11a provided with a silicon oxide vapor deposition film was used. The thickness of the silicon oxide deposited film is 500 nm. The biaxially stretched PBT-based film 11a is a biaxially stretched PBT mixed with PET, and has a PBT content of 50% by weight or more and a PET content of 30% by weight or less. The thickness is 15 μm, the tensile strength in the MD direction is 240 MPa, and the tensile strength in the T direction is 230 MPa.

  Next, the same gas barrier layer 12 and sealant layer 13 as in Example 2 were used. That is, an EVOH film (Kuraray Co., Ltd .: TM-XL, thickness 15 μm) provided with an aluminum vapor deposition film was used for the gas barrier layer 12. Further, a linear low density polyethylene film (manufactured by Tamapoly Co., Ltd .; SE620N, thickness 50 μm) was used for the sealant layer 13.

  And the exterior material 1 of Example 3 was manufactured by dry laminating and integrating these base film 11, gas barrier layer 12, and sealant layer 13.

(Comparative Example 1)
In this example, a biaxially stretched nylon film (thickness: 15 μm) is used as the base film 1.

  The same gas barrier layer 12 and sealant layer 13 as in Example 1 were used. That is, 8021 aluminum foil having a thickness of 7 μm was used for the gas barrier layer 12. Further, a linear low density polyethylene film (manufactured by Tamapoly Co., Ltd .; SE620N, thickness 50 μm) was used for the sealant layer 13.

  And the exterior material 1 of the comparative example 1 was manufactured by dry-laminating and integrating these base film 11, the gas barrier layer 12, and the sealant layer 13.

(Comparative Example 2)
In this example, a biaxially stretched nylon film (manufactured by Toppan Printing Co., Ltd .: GL-AEY, thickness 15 μm) provided with a silicon oxide deposited film is used as the base film 1.

Next, the same gas barrier layer 12 and sealant layer 13 as in Example 2 were used. That is, an EVOH film (Kuraray Co., Ltd .: TM-XL, thickness 15 μm) provided with an aluminum vapor deposition film was used for the gas barrier layer 12. Further, a linear low density polyethylene film (manufactured by Tamapoly Co., Ltd .; SE620N, thickness 50 μm) was used for the sealant layer 13. Then, these base film 11, gas barrier layer 12, and sealant layer 13 were dry laminated. The exterior material 1 of the comparative example 2 was manufactured by integrating.

(Evaluation)
Five items were evaluated for the exterior materials of Examples 1 to 3 and Comparative Examples 1 and 2.

  First, the moisture resistance is evaluated. This evaluation was performed from three viewpoints. That is, first, after these exterior materials were stored for 24 hours under the conditions of 40 ° C. and 90 RH%, whether or not the exterior materials curl was evaluated (curl property evaluation). Table 1 shows the results of curling with “x” and those with no curling as “◯”.

  Next, the core material was vacuum packaged using the exterior material thus stored for 24 hours under the conditions of 40 ° C. and 90 RH%, and its production workability was evaluated (production workability evaluation). The results are shown in Table 1, where “x” indicates that the yield rate has decreased due to curling, and “◯” indicates that the rate is not.

  Next, the exterior material thus stored for 24 hours under the conditions of 40 ° C. and 90 RH% was stored and dried under the conditions of 80 ° C. and 0 RH%, and the time until the weight was stabilized (drying time) was measured. . The results are also shown in Table 1.

  Next, using these exterior materials, glass wool was used as a core material, and an A4 size heat insulating material manufactured by vacuum packaging the glass wool was manufactured, and its physical properties were evaluated. This evaluation was performed from two viewpoints. First is the number of pinholes. Next, after this heat insulating material was stored at 80 ° C. for one month, its thermal conductivity was measured (heat insulating evaluation). Table 1 shows the relative values of the thermal conductivity of each heat insulating material, where the thermal conductivity of Comparative Example 1 is 100. In addition, the one where this value is smaller is excellent in heat insulation.

  From this result, the exterior materials (Examples 1 to 3) using the biaxially stretched PBT-based film are superior in moisture resistance to the exterior materials (Comparative Examples 1 and 2) using the nylon film, and are troublesome. It can be understood that it can be used for the manufacturing process of a heat insulating material, without requiring a dry process. Moreover, since the curl due to moisture absorption is small, the yield is also improved.

  Moreover, if a heat insulating material is manufactured using the exterior material (Examples 1-3) using a biaxially-stretched PBT-type film, the heat insulation material using the exterior material (Comparative Examples 1-2) using a nylon film will be used. In comparison, it can be understood that the number of pinholes is small and the inside of the heat insulating material can be kept in a vacuum state over a long period of time.

1: Exterior material 11: Base film 11a: Biaxially stretched PBT film 11b: Inner film 12: Gas barrier layer 13: Sealant layer 2: Core material A: Heat insulating material

Claims (6)

In order from the outside, the exterior material for a vacuum heat insulating material constituted by laminating a base film, a gas barrier layer and a sealant layer,
For the vacuum heat insulating material, wherein the base film has a single layer structure or a multilayer structure, and a biaxially stretched film containing 50% by weight or more of polybutylene terephthalate is included in the layer structure. Exterior material.   The said biaxially stretched film contains a polyethylene terephthalate, The exterior material for vacuum heat insulating materials of Claim 1 characterized by the above-mentioned.   The polyethylene terephthalate content of the biaxially stretched film is 1 to 50% by weight.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein both the tensile strength in the MD direction and the tensile strength in the TD direction of the outermost layer of the biaxially stretched film are 150 MPa or more. Exterior material.   The said biaxially stretched film is arrange | positioned in the outermost layer of a base film, The exterior material for vacuum heat insulating materials in any one of Claims 1-4 characterized by the above-mentioned.   The vacuum insulating material exterior material according to any one of claims 1 to 5, wherein the gas barrier layer is made of any one of a metal foil, a resin film on which a metal or an inorganic oxide is deposited.

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