JP2011185413A - Method for manufacturing vacuum heat insulation material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a vacuum heat insulation material, in which vacuum leak is reduced with reduced manufacturing man-hours. <P>SOLUTION: The method for manufacturing a vacuum heat insulation material includes: a core housing step for housing a core 2 as a spacer in a sac-like inner bag 10, through a first opening part 10b opened to the sac-like inner bag 10 of which the inner surface is formed of a first thermally-welded layer; an inner bag housing step for housing the inner bag 10 in a sac-like outer package material 20, through a second opening part 20b opened to the sac-like outer package material 20 of which the inner surface is formed of a second thermally welded layer 21; and a welding step welding the first opening part 10b and the second opening part 20b at the same time and sealing the inner bag 10 and the outer package material 20 at the same time, while pressure in the inner bag 10 and outer package material 20 is decreased. A welded part 10a of the first opening part 10b is disposed inside a welded part 20a of the second opening part 20b welded in the welding step. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a vacuum heat insulating material in which the inside of an outer packaging material covering a core material is maintained in a vacuum.

  In order to efficiently use heat in a device such as a refrigerator, a vacuum heat insulating material is used as a heat insulating material. FIG. 7 shows a side sectional view of a conventional vacuum heat insulating material. The vacuum heat insulating material 1 is formed by covering a core material 2 serving as a spacer with an outer packaging material 20. The outer packaging material 20 is formed in a bag shape in which a heat welding layer 21, a barrier layer 22, and a protective layer 23 are laminated.

  The thermal welding layer 21 is disposed on the inner surface of the outer packaging material 20 and seals the outer packaging material 20 by thermal welding. The barrier layer 22 forms an intermediate layer and blocks gas permeation. The protective layer 23 is disposed on the outermost surface of the outer packaging material 20 and prevents damage or the like due to external force. And the edge part of the heat welding layer 21 which pinches | interposes the core material 2 in the state which pressure-reduced the inside of the outer packaging material 20 which inserted the core material 2 is heat-welded. Thereby, the edge part of the outer packaging material 20 is closed by the welding part 20a, and the inside is maintained in a vacuum.

  However, the welded portion 20 a is not covered with the barrier layer 22 and is exposed on the outer surface of the outer packaging material 20. For this reason, when the vacuum heat insulating material 1 is used for many years, as shown by the arrow A, gas enters the inside of the outer packaging material 20 from the welded portion 20a and a vacuum leak occurs. Thereby, there exists a problem that the heat insulation performance of the vacuum heat insulating material 1 falls.

  In order to solve this problem, Patent Document 1 discloses a vacuum heat insulating material that covers a welded portion with a resin having different material permeation characteristics from a heat welded layer. This vacuum heat insulating material forms an intermediate product in which the end portion of the heat-welded layer of the outer packaging material is heat-welded to expose the welded portion on the outer surface. Then, the intermediate product is sandwiched between two resin sheets made of a resin different from the heat welding layer, and the periphery of the resin sheet is heat welded. Thereby, the welding part of a heat welding layer is covered with a resin sheet, and the penetration | invasion of the gas to the inside of an outer packaging material can be prevented with a heat welding layer and a resin sheet.

  Patent Document 2 discloses a vacuum heat insulating material in which an inner bag containing a core material is contained in an outer packaging material. This vacuum heat insulating material accommodates a core material in an inner bag and thermally welds the end portion of the inner bag to form a welded portion. Next, the inner bag is accommodated in an outer packaging material having a heat welding layer made of the same material as the inner bag, and the end portion of the outer packaging material is thermally welded with the welding portion of the inner bag interposed therebetween. Thereby, the welding part of an inner bag forms a welding material at the time of heat welding of an outer packaging material, and an outer packaging material can be sealed reliably.

Japanese Patent Laying-Open No. 2006-77790 (pages 5-8, FIG. 6) Japanese Patent No. 4215701 (pages 5-12, FIG. 6)

  However, according to the vacuum heat insulating material disclosed in Patent Document 1, since the resin sheet is thermally welded after the outer packaging material is thermally welded, there is a problem that the number of manufacturing steps is increased. Further, according to the vacuum heat insulating material disclosed in Patent Document 2, since the outer packaging material is thermally welded after the inner bag is thermally welded as described above, there is a problem that the number of manufacturing steps is increased.

  An object of this invention is to provide the manufacturing method of the vacuum heat insulating material which can reduce a manufacturing man-hour and can reduce a vacuum leak.

  In order to achieve the above object, the present invention inserts a core material serving as a spacer into the inner bag through a first opening that has an inner surface opened in a bag-shaped inner bag formed of a first heat-welded layer. A core material accommodating step, and an inner bag accommodating step of inserting the inner bag into the outer packaging material through a second opening having an inner surface opened to the bag-shaped outer packaging material formed by the second heat-welded layer. A welding step of simultaneously welding the first opening and the second opening in a state where the inside of the inner bag and the outer packaging material is decompressed, and simultaneously sealing the inner bag and the outer packaging material, the welding step The welded portion of the first opening is disposed on the inner side of the welded portion of the second opening that has been welded in (1).

  According to this configuration, the core material is inserted into the inner bag from the first opening provided on at least one side of the bag-shaped inner bag in the core material accommodation step. Next, the inner bag is inserted into the outer packaging material from the second opening provided on at least one side of the bag-shaped outer packaging material in the inner bag housing step. Next, the inside of the inner bag and the outer packaging material is depressurized in the welding step, and the first opening and the second opening are simultaneously heat-pressed. Thereby, the 1st heat welding layer of an inner bag and the 2nd heat welding layer of an outer packaging material fuse | melt, a 1st opening part and a 2nd opening part are welded, and an inner bag and an outer packaging material are sealed simultaneously. At this time, the welded portion of the first opening is disposed inside the welded portion of the second opening, thereby preventing the intrusion of outside air.

  Moreover, the present invention is characterized in that, in the method for manufacturing a vacuum heat insulating material having the above-described configuration, the melting point of the first heat-welded layer is lower than the melting point of the second heat-welded layer. According to this structure, it heats from the outer side of the outer packaging material which covers an inner bag at a welding process, and the 1st opening part of an inner bag becomes low temperature rather than the 2nd opening part of an outer packaging material. Thereby, a 1st heat welding layer and a 2nd heat welding layer can be welded at optimal temperature.

  In the method for producing a vacuum heat insulating material having the above-described configuration, the water vapor permeability of one of the first heat-welded layer and the second heat-welded layer is lower than the other, and the oxygen permeability of the other is lower than the other. It is characterized by. According to this configuration, the penetration of water vapor is prevented by one of the welded portion of the first opening and the welded portion of the second opening, and the penetration of oxygen is prevented by the other.

  Further, the present invention is characterized in that, in the vacuum heat insulating material manufacturing method having the above-described configuration, the first heat-welded layer is formed of polyethylene and the second heat-welded layer is formed of polyacrylonitrile. According to this configuration, the melting point of polyethylene is lower than the melting point of polyacrylonitrile, and the first heat welding layer and the second heat welding layer are welded at an optimum temperature. Further, the penetration of water vapor is prevented by the welded portion of the first opening, and the penetration of oxygen is prevented by the welded portion of the second opening.

  According to the present invention, since the first opening of the inner bag into which the core material is inserted and the second opening of the outer packaging material into which the inner bag is inserted are simultaneously heat-sealed and sealed, the number of manufacturing steps of the vacuum heat insulating material can be reduced. Can do. Moreover, since the welding part of a 1st opening part is distribute | arranged inside the welding part of a 2nd opening part, the penetration | invasion of external air can be prevented and the vacuum leak of a vacuum heat insulating material can be reduced.

Side surface sectional drawing which shows the vacuum heat insulating material of embodiment of this invention Process drawing which shows the manufacturing process of the vacuum heat insulating material of embodiment of this invention The perspective view which shows the core material accommodation process and inner bag accommodation process of the vacuum heat insulating material of embodiment of this invention. The perspective view which shows the state after the inner bag accommodation process of the vacuum heat insulating material of embodiment of this invention. A-A 'sectional view of FIG. Side surface sectional drawing which shows the welding process of the vacuum heat insulating material of embodiment of this invention Side sectional view showing a conventional vacuum heat insulating material

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a vacuum heat insulating material of one embodiment. For convenience of explanation, the same parts as those of the conventional example shown in FIG. The vacuum heat insulating material 1 accommodates the core material 2 inside the inner bag 10 and accommodates the inner bag 10 inside the outer packaging material 20.

  As the core material 2, foamed resin, powder, inorganic fiber, porous body, thin film laminate, and the like can be used. Specifically, continuous urethane, silica powder, glass fiber, and the like are used. In this embodiment, glass fiber is used.

  The inner bag 10 is formed in a bag shape in which the peripheral edges of two films are thermally welded. As a material for the film forming the inner bag 10, low density polyethylene, linear low density polyethylene, high density polyethylene, unstretched polypropylene, polyacrylonitrile, unstretched polyethylene terephthalate, or the like can be used. In this embodiment, low-density polyethylene having a thickness of 20 μm is used.

  In addition, since the inner bag 10 is formed of a single layer film, a heat-welding layer (first heat-welding layer) on which the entire inner bag 10 including the inner surface is heat-welded is formed. The inner bag 10 may be formed of a laminated film and a heat welding layer may be provided on the inner surface.

  The outer packaging material 20 is formed in a bag shape in which the peripheral edges of two laminated films obtained by laminating a heat-welding layer 21, a barrier layer 22, and a protective layer 23 are heat-welded. The thermal welding layer 21 is disposed on the inner surface of the outer packaging material 20 and seals the outer packaging material 20 by thermal welding. As the heat welding layer 21, low density polyethylene, linear low density polyethylene, high density polyethylene, unstretched polypropylene, polyacrylonitrile, unstretched polyethylene terephthalate, or the like can be used. In this embodiment, polyacrylonitrile having a thickness of 30 μm is used.

  The barrier layer 22 forms an intermediate layer and blocks the permeation of gas containing water vapor. As the barrier layer 22, an aluminum foil, an aluminum deposited film, or the like can be used. In the present embodiment, an aluminum foil having a thickness of 6 μm is used and bonded to the heat welding layer 21 with an organic solvent-based adhesive. The protective layer 23 is disposed on the outermost surface of the outer packaging material 20 and prevents damage or the like due to external force. As the protective layer 23, polyamide, PET, or the like can be used. In this embodiment, polyamide having a thickness of 15 μm is used and bonded to the barrier layer 22 by an organic solvent-based adhesive.

  The inside of the inner bag 10 and the outer packaging material 20 is maintained in a vacuum, and is thermally welded at the welded portions 10a and 20a at one end. As will be described in detail later, the welded portion 10a of the inner bag 10 and the welded portion 20a of the outer packaging material 20 are thermally welded simultaneously, and the welded portion 10a is arranged inside the welded portion 20a.

  FIG. 2 is a process diagram showing a manufacturing process of the vacuum heat insulating material 1. The vacuum heat insulating material 1 is created by a core material drying process, a core material housing process, an inner bag housing process, a welding process, and an inspection process. In the core material drying step, the core material 2 is dried. Specifically, the core material 2 made of glass fiber is placed in an atmosphere of 200 ° C. for 20 minutes and dried.

  FIG. 3 is a perspective view showing a core material accommodation step and an inner bag accommodation step. The inner bag 10 is formed in a bag shape having an opening 10b (first opening) on one side, and the core material 2 is inserted into the inner bag 10 from the opening 10b as indicated by an arrow B1 in the core material housing step. The Thereby, the core material 2 is accommodated in the inner bag 10.

  The outer packaging material 20 is formed in a bag shape having an opening 20b (second opening) on one side, and the inner bag 10 is inserted into the outer packaging material 20 from the opening 20b as indicated by an arrow B2 in the inner bag housing step. The 4 shows a perspective view of this state, and FIG. 5 shows a cross-sectional view taken along the line A-A ′ of FIG. 4. The core material 2 is arranged in the inner bag 10 with the opening 10b opened, and the inner bag 10 is arranged in the outer packaging material 20 with the opening 20b opened.

  FIG. 6 shows a side sectional view of the welding process. The outer packaging material 20 including the core material 2 and the inner bag 20 is disposed in the chamber, and the pressure in the chamber is reduced to, for example, 0.015 Torr. And the opening part 20b (refer FIG. 5) is inserted | pinched from the two directions of the outer side of the protective layer 23 of the outer packaging material 20 with the silicon heater 30, and it heats by pressure.

  At this time, the opening 10 b (see FIG. 5) of the inner bag 10 is sandwiched by the silicon heater 30. Thereby, the opening part 10b of the inner bag 10 and the opening part 20b of the outer packaging material 20 are heat-sealed simultaneously, and the inner bag 10 and the outer packaging material 20 are simultaneously sealed while maintaining the inside in a vacuum. Moreover, the welding part 10a which heat-welded the opening part 10b is arrange | positioned inside the welding part 20a which heat-welded the opening part 20b (core material 2 side).

  Then, sealing defects and scratches are inspected in the inspection process. Thereby, the vacuum heat insulating material 1 shown in FIG. 1 is obtained.

  Since the opening 10a for inserting the core material 2 and the opening 20a for inserting the inner bag 10 are simultaneously heat-sealed and sealed in the vacuum heat insulating material 1, the number of manufacturing steps for the vacuum heat insulating material 1 can be reduced. Further, since the welded portion 10a of the opening 10b is arranged inside the welded portion 20a of the opening 20b, the intruding outside air is doubled by the welded portion 10a and the welded portion 20a as shown by the arrow A (see FIG. 1). Shielded by. Therefore, the vacuum leak of the vacuum heat insulating material 1 can be reduced.

  At this time, it is desirable that the welded portion 10a and the welded portion 20a have lower water vapor permeability and oxygen permeability. In general, however, general-purpose resins have low oxygen permeability and low gas permeability but high water vapor permeability, and low water vapor permeability and high gas permeability (including oxygen) other than water vapor. Have

  For this reason, a material having a low water vapor transmission rate is used for one of the inner bag 10 that forms the heat-welded layer thermally welded by the welded portion 10a and the heat-welded layer 21 of the outer packaging material 20 that is heat-welded by the welded portion 20a. If a material having a low oxygen permeability is used, the invasion of gas containing water vapor can be reduced.

The water vapor permeability of the low density polyethylene film (thickness 25 μm) is about 18 g / m ² · day (2.08 × 10 ⁻⁸ g / cm ² · sec) at 40 ° C. and 90% RH. The low-density polyethylene film has an oxygen permeability of about 4000 cc / m ² · day · atm (4.57 × 10 ⁻¹¹ cm ³ / cm ² · sec · Pa) at 20 ° C. and 90% RH.

On the other hand, the oxygen permeability of the polyacrylonitrile film (thickness 25 [mu] m) is lower than the low density polyethylene film, 20 ° C., in 90% RH to about ^{13cc / m 2 · day · atm} (1.48 × 10 -13 cm 3 / cm ² · sec · Pa). The water vapor permeability of the polyacrylonitrile film is higher than that of the low density polyethylene film, and is about 82 g / m ² · day (9.49 × 10 ⁻⁸ g / cm ² · sec) at 40 ° C. and 90% RH.

  For this reason, the penetration | invasion of water vapor | steam and oxygen can be reduced by using a polyacrylonitrile and a low density polyethylene film for the heat welding layer 21 and the inner bag 10 of the outer packaging material 20, respectively. The inner bag 10 may be a linear low density polyethylene or high density polyethylene having the same characteristics as the low density polyethylene film.

  At this time, the melting point of polyacrylonitrile forming the heat-welded layer 21 is about 140 ° C., and the melting point of low-density polyethylene forming the inner bag 10 is about 110 ° C. In the welding process, since the outer packaging material 20 that covers the inner bag 10 is heated from the outside, the opening 10 b of the inner bag 10 becomes cooler than the opening 20 b of the outer packaging material 20. For this reason, by making the melting point of the inner bag 10 lower than the melting point of the heat welding layer 21, the welding part 10a and the welding part 20a can be welded at an optimum temperature.

  According to the present embodiment, the opening 10b (first opening) of the inner bag 10 into which the core material 2 is inserted and the opening 20b (second opening) of the outer packaging material 20 into which the inner bag 10 is inserted are heat-sealed simultaneously. Therefore, the number of manufacturing steps for the vacuum heat insulating material 1 can be reduced. Moreover, since the welding part 10a of the opening part 10b is distribute | arranged inside the welding part 20a of the opening part 20b, the penetration | invasion of external air can be prevented and the vacuum leak of the vacuum heat insulating material 1 can be reduced.

  Further, since the melting point of the inner bag 10 (first heat welding layer) forming the heat welding layer is lower than the melting point of the heat welding layer 21 (second heat welding layer) of the outer packaging material 20, heating is performed from the outside of the outer packaging material 20. In this case, the welded portion 10a and the welded portion 20a can be welded at an optimum temperature.

  Further, the water vapor permeability of one of the inner bag 10 (first heat-welded layer) and the heat-welded layer 21 (second heat-welded layer) of the outer packaging material 20 forming the heat-welded layer is lower than the other, and the other oxygen-permeable Since the degree is lower than that of one, the invasion of gas containing water vapor and oxygen can be prevented.

  Further, since the inner bag 10 (first heat-welding layer) that forms the heat-welding layer is formed of polyethylene and the heat-welding layer 21 (second heat-welding layer) of the outer packaging material 20 is formed of polyacrylonitrile, the heat-welding is performed. The vacuum heat insulating material 1 in which the melting point and water vapor permeability of the inner bag 10 are lower than that of the layer 21 and the oxygen permeability of the heat welding layer 21 is lower than that of the inner bag 10 can be easily realized.

  According to this invention, it can utilize for the vacuum heat insulating material by which the inside of the outer packaging material which covers a core material is maintained at a vacuum.

DESCRIPTION OF SYMBOLS 1 Vacuum heat insulating material 2 Core material 10 Inner bag 10a, 20a Welding part 10b, 20b Opening part 20 Outer packaging material 21 Thermal welding layer 22 Barrier layer 23 Protective layer 30 Silicon heater

Claims (4)

  A core material containing step of inserting a core material serving as a spacer into the inner bag through a first opening portion whose inner surface is opened in a bag-shaped inner bag formed by the first heat-welded layer; (2) an inner bag accommodating step of inserting the inner bag into the outer packaging material through a second opening portion opened in the bag-shaped outer packaging material formed by the heat-welded layer, and the inner bag and the outer packaging material. A welding step of simultaneously welding the first opening and the second opening in a decompressed state and simultaneously sealing the inner bag and the outer packaging material, and a welded portion of the second opening welded in the welding step A method for manufacturing a vacuum heat insulating material, characterized in that a welded portion of the first opening is disposed on the inside.   The method for producing a vacuum heat insulating material according to claim 1, wherein the melting point of the first heat welding layer is lower than the melting point of the second heat welding layer.   3. The vacuum heat insulation according to claim 1, wherein the water vapor permeability of one of the first heat-welded layer and the second heat-welded layer is lower than the other, and the oxygen permeability of the other is lower than the other. A method of manufacturing the material.   The method for producing a vacuum heat insulating material according to claim 2 or 3, wherein the first heat-welded layer is formed of polyethylene and the second heat-welded layer is formed of polyacrylonitrile.

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