JP2009041592A - Vacuum heat insulating material and insulation box - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum heat insulating material excellent in the easiness in handling and the heat insulating performance and provide an insulation box fitted with the vacuum heat insulating material. <P>SOLUTION: The vacuum heat insulating material is equipped with a gas barrier vessel (sheathing) having air shutoff property and a core material and gas adsorbent encapsulated in the sheathing decompressed to a prescribed degree of vacuum. The core material 5 has a laminate structure consisting of a laminate of organic fiber sheets (fiber gathering) 1 formed from a plurality of organic fibers arranged at a prescribed spacing and a plurality of organic fibers arranged at a prescribed spacing in the direction crossing the first named fibers. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vacuum heat insulating material and a heat insulating box, and more particularly to a vacuum heat insulating material and a heat insulating box suitable for use in a cooling / heating apparatus.

  Conventionally, urethane has been used as a heat insulating material, but nowadays, vacuum heat insulating materials having better heat insulating performance than urethane are used in combination with urethane. Such a vacuum heat insulating material is used not only for a refrigerator but also for a cooling device such as a heat insulation box, a vehicle air conditioner, and a water heater.

A vacuum insulation material is a powder, foam, fiber, etc. inserted as a core material into an envelope made of aluminum foil with gas barrier properties (same as air barrier properties), and the inside is kept at a vacuum level of several Pa. It is what is leaning.
In addition to air and moisture entering from the outside air as one of the causes of the deterioration of the heat insulation performance of the vacuum heat insulating material, there are outgas generated from the core material and moisture present in the core material itself. Is inserted into the outer packaging.
There are powders such as silica, foams such as urethane, and fiber bodies such as glass as the core material of the vacuum heat insulating material. Currently, fiber bodies having the best heat insulation performance are mainly used.

There are two types of fiber bodies: inorganic fibers and organic fibers.
Examples of inorganic fibers include glass fibers and carbon fibers (see, for example, Patent Documents 1 and 8).
Examples of the organic fiber include polypropylene fiber, polylactic acid fiber, aramid fiber, LCP (liquid crystal polymer) fiber, polyethylene terephthalate fiber, polyester fiber, polyethylene fiber, and cellulose fiber (see, for example, Patent Documents 2 and 7).

Examples of the shape of the fibrous body include a cotton-like shape and a laminate of sheets (for example, see Patent Documents 3 and 4).
In addition, some fiber bodies are formed by laminating sheets so that fiber orientations alternate (see Patent Documents 5 and 6).

JP-A-8-028776 (page 2-3) JP 2002-188791 A (page 4-6, FIG. 1) Japanese Patent Laying-Open No. 2005-344832 (page 3-4, FIG. 1) JP 2006-307924 A (page 5-6, FIG. 2) JP 2006-017151 A (page 3, FIG. 1) Japanese Examined Patent Publication No. 7-103955 (second page, FIG. 2) JP 2006-283817 A (pages 7-8) Japanese Patent Laying-Open No. 2005-344870 (page 7, FIG. 2)

In conventional vacuum insulation, glass fiber or polyester fiber is used as a core material.
Since glass fiber is hard and brittle, dust may scatter during the manufacture of vacuum heat insulating material and adhere to the skin, mucous membrane, etc. of the worker, which may cause irritation, and its handling and workability are problematic. Also, when considering the scene of recycling, for example, in a refrigerator, each product is pulverized in a recycling factory, and glass fiber is mixed with urethane scraps and used for thermal recycling. There is a disadvantage that recyclability is not good.

  On the other hand, although organic fibers such as polyester are excellent in handleability and recyclability, the thermal conductivity, which is an indicator of heat insulation performance, is 0.0030 W / mK (see Patent Document 7), whereas in glass fibers, It was 0.0013 W / mK (refer to Patent Document 8), and there was a defect that the heat insulation performance was poor.

  The present invention has been made in order to solve the above-described problems, and provides a vacuum heat insulating material excellent in handleability and heat insulating performance, and a heat insulating box including the vacuum heat insulating material.

The vacuum heat insulating material according to the present invention is a vacuum heat insulating material in which a core material is housed in a gas barrier container and the inside is in a reduced pressure state.
The core material has a laminated structure of an organic fiber assembly in which organic fibers are formed in a sheet shape.

  Therefore, since the vacuum heat insulating material according to the present invention is configured by laminating sheet-like organic fiber aggregates, it is excellent in handling property and recyclability and excellent in heat insulating performance.

[Embodiment 1: Vacuum heat insulating material]
1 to 4 schematically show a vacuum heat insulating material according to Embodiment 1 of the present invention. FIG. 1 is a perspective view in which core materials are thinly laminated, and FIG. 2 shows fiber orientation in one sheet. FIG. 3 is a side view showing the orientation of the fiber when there is a thickness, and FIG. 4 is an exploded perspective view showing the configuration of the vacuum heat insulating material.
In FIG. 4, the vacuum heat insulating material 7 includes a gas barrier container (hereinafter referred to as “external packaging material”) 4 having an air barrier property, a core material 5 and a gas adsorbent 6 enclosed inside the external packaging material 4, have. And the inside of the outer packaging material 4 is depressurized to a predetermined degree of vacuum.

(Laminated structure)
In FIG. 1, the core material 5 has a laminated structure in which sheet-like organic fiber aggregates (hereinafter referred to as “fiber aggregates”) 1 are laminated.
In FIG. 2, the fiber assembly 1 includes a plurality of organic fibers 2x arranged at a predetermined interval and a plurality of organic fibers arranged at a predetermined interval in a direction orthogonal to the organic fibers 2x. 2y. At this time, the organic fiber 2x and the organic fiber 2y are in point contact. And by laminating | stacking the fiber assembly 1 thinly, since the orientation of the fiber to a heat-transfer direction can be suppressed, thermal conductivity can be lowered | hung.
In addition, although the above has shown the case where the organic fiber 2x and the organic fiber 2y are orthogonal to each other, the present invention is not limited to this, and may intersect at an angle that is not perpendicular to each other.

(Organic fiber)
As the material used for the organic fiber 2 forming the core material 5 of the vacuum heat insulating material 7, polyester is used in the first embodiment, but in addition, polypropylene, polylactic acid, aramid, LCP (liquid crystal polymer), or the like may be used. it can.
Since polypropylene has low hygroscopicity, drying time and evacuation time can be shortened and productivity can be improved. Since solid heat conduction is small, improvement in heat insulation performance of the vacuum heat insulating material can be expected.
Moreover, since polylactic acid is biodegradable, the core material disassembled and separated after use of the product can be subjected to landfill treatment.
In addition, since aramid and LCP have high rigidity, they have good merits such as good shape retention when vacuum-packed and subjected to atmospheric pressure, can increase the porosity, and can be expected to improve heat insulation performance.

(Fiber assembly)
A fiber assembly (same as an organic fiber assembly and a sheet-like assembly) 1 that forms the core material 5 is a polyester resin that is heated and melted from a number of nozzles arranged in a row in a row with respect to the width to be manufactured. It is allowed to drop freely, and is manufactured by pressing and winding with a roller while moving the conveyor at an arbitrary speed.
The bulk density of the fiber assembly 1 can be adjusted by the amount of molten resin discharged and the speed of the conveyor to obtain fiber assemblies having different thicknesses.

  In addition, since the fiber assembly 1 obtained by the above-mentioned method is not easy to handle at the time of manufacturing the vacuum heat insulating material because the organic fibers 2 are separated, the organic fibers 2 are heated and welded together during pressurization. In this case, excessive pressurization and heat welding increase the contact area between the organic fibers 2 and increase heat transfer. Therefore, it is better to reduce the contact area as much as possible, 5% or less of the total area. It is desirable to keep it at a minimum.

  Next, the obtained fiber assembly 1 was cut into A4 size, and this was laminated in 25 layers to form the core material 5. In addition, you may set the number of sheets to laminate | stack arbitrarily based on the thickness of the obtained fiber assembly 1, and the thickness of the vacuum heat insulating material 7 to manufacture. In the first embodiment, the fiber diameter of the fiber assembly 1 is adjusted by the diameter of the nozzle for molding the fiber aggregate 1 and is about 15 μm. However, it is better for the heat insulation performance to be narrower, and theoretically the fiber diameter is desirably 10 μm or less. .

(Outer packaging material)
As the outer packaging material 4 of the vacuum heat insulating material 7, a plastic laminate film having a gas barrier property composed of nylon (6 μm), aluminum vapor-deposited PET (10 μm), aluminum foil (6 μm), and high-density polyethylene (50 μm) was used.
In addition, when a laminate film that does not include an aluminum foil such as a configuration of polypropylene, polyvinyl alcohol, or polypropylene is used, it is possible to suppress a decrease in heat insulation performance due to a heat bridge. Of the four sides, three sides are heat sealed by a seal wrapping machine.

(Production method)
The vacuum heat insulating material 7 is manufactured by inserting the core material 5 into the outer packaging material 4 which is a bag, fixing it so that the other side of the mouth is not closed, and keeping it at a temperature of 105 ° C. for half a day (about 12 hours). ) After drying, the film bag contains a gas adsorbent 6 for adsorbing residual gas after vacuum packaging, outgas from the core material 5 released over time, and permeated gas entering through the sealing layer of the outer packaging material 4. It inserted in and vacuum-evacuated with the Kashiwagi-type vacuum packaging machine (NPC company make; KT-650). Vacuuming was performed until the degree of vacuum in the chamber reached about 1 to 10 Pa, and the film bag opening was heat sealed in the chamber as it was to obtain a plate-like vacuum heat insulating material 7.

(Insulation performance)
Next, the influence which the thickness of the fiber assembly 1 has on the heat insulation performance will be described for Examples 1 to 4 as the fiber assembly 1 of the present invention and a comparative example for comparison.
The comparative material used the cotton-like polyester which is the same diameter as the fiber diameter (about 15 micrometers) of Examples 1-4 for the core material, and obtained the vacuum heat insulating material by the method similar to the above.
The manufactured Examples 1 to 4 and Comparative Example (both vacuum heat insulating materials) were measured using a thermal conductivity meter “AutoΛ HC-073 (manufactured by Eihiro Seiki Co., Ltd.)” with an upper temperature of 37.7 ° C. and a lower temperature. The thermal conductivity at a temperature difference of 10.0 ° C. was measured. The measurement was made after 1 day from the vacuuming step.

  Here, the thickness of one fiber assembly 1 is a value obtained by subtracting twice the thickness of the outer packaging material 4 from the thickness of the vacuum heat insulating material 7 and then dividing it by the number of laminated layers. Moreover, the average fiber diameter was made into the average value of 100 measured values measured using the microscope. Table 1 shows the result of dividing the thickness after vacuuming by the average fiber diameter.

FIG. 5 is a correlation diagram for explaining the heat insulating performance of the vacuum heat insulating material according to Embodiment 1 of the present invention, in which the horizontal axis is a numerical value obtained by dividing the sheet thickness of the fiber assembly 1 by the average fiber diameter, and the vertical axis is It is the insulation performance ratio. In addition, the heat insulation performance ratio is a numerical value obtained by dividing the thermal conductivity of the comparative example by the thermal conductivity of Examples 1 to 4, respectively (the value obtained by dividing the thermal conductivity of Examples 1 to 4 by the thermal conductivity of the comparative example. Is the same as the inverse of
From FIG. 5, it can be seen that when the thickness of the fiber assembly 1 is less than 18 times the average fiber diameter, the heat insulation performance is improved as compared with the comparative example in which the cotton-like fiber is used as the core material. This is because the smaller the thickness of the fiber assembly 1, the more easily the fibers are oriented in the plane direction perpendicular to the heat insulation direction, that is, the solid heat transfer path in the vacuum heat insulating material 7 in the heat insulation direction can be lengthened. It is thought that the heat insulation performance was improved.
Moreover, the closer the thickness of the fiber assembly 1 is to the average fiber diameter, the better the heat insulation performance. Therefore, it was found that the thickness of the fiber assembly 1 is preferably 1 to 18 times the fiber diameter.
In addition, when the thickness of the fiber assembly 1 is 8 times or less of the fiber diameter, the heat insulation performance is abruptly (extremely) improved. Therefore, the thickness of the fiber assembly is 1 to 8 times the average fiber diameter. More desirable.

[Embodiment 2: Vacuum insulation]
6 and 7 are perspective views schematically showing a lamination procedure of core materials forming the vacuum heat insulating material according to Embodiment 2 of the present invention.
In FIG. 6, the core material 5 is shown to be formed by being laminated while being folded in a continuous sheet shape without cutting the fiber assembly 1.
In FIG. 7, a sheet-like first fiber assembly 1x that is continuous without cutting and a sheet-like second fiber assembly 1y that is continuous without cutting are used. (It may be referred to as “fiber assembly 1”), and the two layers are arranged so as to cross each other, and the state of being formed by being laminated so that the range between the folds overlaps every fold is shown. Yes.

That is, by laminating the fiber assembly 1 while being folded, it is possible to efficiently manufacture the core material 5 and thus the vacuum heat insulating material 7 without the need for cutting.
Since the fiber assembly 1 used here is made by the above manufacturing method, the organic fiber 2 is oriented in the longitudinal direction. If attention is paid to this and the fiber assemblies 1 are laminated so as to intersect with each other, the point of contact approaches and the heat insulation performance is further improved.

[Embodiment 3: Refrigerator]
FIG. 8 illustrates a heat insulating box according to the third embodiment of the present invention, and is a cross-sectional view in front view schematically illustrating a refrigerator. The same parts as those in the first and second embodiments are denoted by the same reference numerals, and a part of the description is omitted.
In FIG. 8, the refrigerator 100 includes an outer box 9, an inner box 10 disposed inside the outer box 9, a vacuum heat insulating material 7 and a polyurethane foam 11 disposed in a gap between the outer box 9 and the inner box 10. And a refrigeration unit (not shown) for supplying cold heat into the inner box 10. The outer box 9 and the inner box 10 each have an opening formed on a common surface, and an opening / closing door is installed in the opening (both not shown).

At this time, since the outer packaging material 4 of the vacuum heat insulating material 7 includes the aluminum foil, there is a possibility that a heat bridge in which heat flows through the aluminum foil is generated. For this reason, in order to suppress the influence of this heat bridge, the vacuum heat insulating material 7 is arrange | positioned away from the coated steel plate of the outer box 9 using the spacer 8 which is a resin molded product. In addition, the spacer 8 is appropriately provided with a hole for not inhibiting the flow so that no void remains in the polyurethane foam injected into the heat insulating wall in a later step.
That is, the refrigerator 100 has a heat insulating wall 12 formed by the vacuum heat insulating material 7, the spacer 8, and the polyurethane foam 11. In addition, the range in which the heat insulation wall 12 is disposed is not limited, and may be the entire range or a part of the gap formed between the outer box 9 and the inner box 10, and You may arrange | position inside an opening-and-closing door.

When the refrigerator 100 is used, it is dismantled and recycled at recycling centers in various places based on the Home Appliance Recycling Law. At this time, since the refrigerator 100 of the present invention has the vacuum heat insulating material 7 in which the core material 5 made of the fiber assembly 1 (formed by the organic fibers 2) is disposed, the vacuum heat insulating material 7 is not removed. The crushing process can be performed, and the recyclability is good without causing a reduction in combustion efficiency or a residue during thermal recycling.
On the other hand, in the refrigerator in which the vacuum heat insulating material is arranged, in the case of the vacuum heat insulating panel in which the core material of the vacuum heat insulating material is an inorganic powder, the powder is scattered, so the crushing treatment cannot be performed as the box, It takes a lot of time to remove the vacuum insulation from the refrigerator box.

In addition, in the case of a vacuum insulation panel whose core material is glass fiber, although it can be crushed as it is in a box, the crushed glass fiber is mixed with polyurethane foam pulverized material and subjected to thermal recycling, At this time, there is a difficulty in recyclability such as lowering combustion efficiency or becoming a residue after combustion.
In addition, although the above has illustrated the refrigerator as a heat insulation box, this invention is not limited to this, Cold-heat equipment or thermal equipment, such as a heat retention box, a vehicle air conditioner, a water heater, Furthermore, predetermined | prescribed Instead of a box having a shape, a heat insulating bag (heat insulating container) having a deformable outer bag and an inner bag may be used.

  As described above, since the vacuum heat insulating material and the heat insulating box of the present invention are excellent in handling property, heat insulating performance and recyclability, they are widely used as a heat insulating box or a heat insulating container in various forms as a vacuum heat insulating material installed in various devices. can do.

The perspective view which laminated | stacked the core material of the vacuum heat insulating material which concerns on Embodiment 1 of this invention thinly. The side view showing the orientation of the fiber in the sheet | seat of the vacuum heat insulating material shown in FIG. The side view which shows the orientation condition of the fiber in case there is thickness of the vacuum heat insulating material shown in FIG. The disassembled perspective view which shows the structure of the vacuum heat insulating material shown in FIG. The correlation diagram explaining the heat insulation performance of the vacuum heat insulating material shown in FIG. The perspective view which shows the lamination | stacking point of the core material of the vacuum heat insulating material which concerns on Embodiment 2 of this invention. The perspective view which shows the lamination | stacking point of the core material of the vacuum heat insulating material which concerns on Embodiment 2 of this invention. Sectional drawing which shows typically the heat insulation box (refrigerator) which concerns on Embodiment 3 of this invention.

Explanation of symbols

  1: fiber aggregate (sheet-like organic fiber aggregate), 2: organic fiber, 2x: organic fiber, 2y: organic fiber, 3: gap, 4: outer packaging material, 5: core material, 6: gas adsorbent, 7 : Vacuum heat insulating material, 8: spacer, 9: outer box, 10: inner box, 11: polyurethane foam, 12: heat insulating wall, 100: refrigerator.

Claims (8)

It is a vacuum heat insulating material in which a core material is housed in a gas barrier container and the inside is in a reduced pressure state,
The vacuum heat insulating material, wherein the core material has a laminated structure of an organic fiber assembly in which organic fibers are formed in a sheet shape.   2. The vacuum heat insulation according to claim 1, wherein the thickness of the organic fiber aggregate is 1 to 18 times the diameter of the organic fiber when accommodated in the gas barrier container in a reduced pressure state. Wood.   The vacuum heat insulating material according to claim 1 or 2, wherein the organic fiber aggregate is formed into a sheet shape by press-welding continuous organic fibers.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein the core material is formed by folding and stacking the organic fiber assembly. The core material is formed from a first organic fiber assembly that is folded and laminated, and a second organic fiber assembly that is folded and laminated,
The vacuum heat insulating material according to claim 4, wherein the first organic fiber aggregate and the second organic fiber aggregate are folded so as to cross each other. An outer box,
An inner box disposed inside the outer box;
A heat insulating box, wherein the vacuum heat insulating material according to any one of claims 1 to 5 is disposed in all or part of a gap between the outer box and the inner box.   A heat insulating box, wherein a heat insulating material is filled in both or one of the space between the outer box and the vacuum heat insulating material or between the inner box and the vacuum heat insulating material.   A heat insulating box comprising temperature adjusting means for adjusting the temperature inside the inner box.

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