JP2011027204A - Vacuum heat insulation material and insulation box provided with this vacuum heat insulation material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum heat insulation material having excellent heat insulation properties, handling properties, productivity, and recyclability by properly heat-embossing a long fiber assembly. <P>SOLUTION: The vacuum heat insulation material 4 is produced by accommodating a core material 1 in a gas barrier container and sealing the container while decompressing the interior of the container, wherein the core material 1 is formed by laminating a thermoplastic resin long fiber assembly 1a, the long fiber assembly 1a is heat-embossed and formed in a sheet form, the thickness t of the heat-embossed long fiber assembly 1a under a decompression sealing condition is 80% or more of the thickness T of a long fiber assembly 10a not subjected to heat-embossing 5 under the decompression sealing condition, preferably 80 to 90%. The thickness of the heat-embossed long fiber assembly 1a is controlled by controlling the clearance of a calendar roll. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vacuum heat insulating material and a heat insulating box provided with the vacuum heat insulating material, and more particularly to a vacuum heat insulating material suitable for use in a refrigeration apparatus and a heat insulating box provided with the vacuum heat insulating material.

  In recent years, from the viewpoint of preventing global warming, reduction of power consumption of home appliances has been demanded. In particular, the percentage of power consumption of refrigerators in general households is large, and the reduction is indispensable. In order to reduce the power consumption of the refrigerator, it is important to improve the efficiency of the compressor and the performance of the heat insulating material.

  Conventionally, polyurethane foam (hereinafter referred to as PUF) is used as a heat insulating material, but in recent years, a vacuum heat insulating material having better heat insulating performance than PUF has been used in combination with PUF. Such vacuum heat insulating materials are used not only for refrigerators but also for refrigeration equipment such as heat insulation boxes, vehicle air conditioners, and water heaters.

  A vacuum heat insulating material is a powder, foam, fiber, etc. inserted as a core material into an outer packaging material made of a gas barrier (air barrier) aluminum foil laminate film, etc., and the inside has a degree of vacuum of several Pa. It is what is being held.

  As core materials for vacuum heat insulating materials, there are powders such as silica, foams such as urethane, and fiber bodies such as glass. At present, however, fiber bodies having the most excellent heat insulation performance are mainly used.

  The fibrous body includes inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers and carbon fibers (see, for example, Patent Documents 1, 4, and 6). Examples of organic fibers include polystyrene fibers, polypropylene fibers, polylactic acid fibers, aramid fibers, and LCP (liquid crystal polymer) fibers. , Polyethylene terephthalate fiber, polyester fiber, polyethylene fiber, cellulose fiber and the like (for example, see Patent Documents 2, 3, 5, 7, and 8).

JP-A-8-028776 (pages 2 to 3) Japanese Patent No. 3656028 (page 5) Japanese Patent Laying-Open No. 2006-283817 (pages 7-8) Japanese Patent Laying-Open No. 2005-344870 (page 7, FIG. 2) Japanese Patent No. 4012903 (page 3) JP 2008-185220 A (pages 4 to 5) JP 2006-29505 A (page 4) JP 2009-41592 A (page 4)

In Patent Literatures 1 to 8, inorganic fibers such as glass fibers and organic fibers such as polyester are used as the core material for the vacuum heat insulating material.
Since glass fiber is hard and brittle, dust is scattered during the manufacture of the vacuum heat insulating material, which may cause irritation if it adheres to the skin, mucous membrane, etc. of the worker, and there is a problem in the working environment. Also, when considering the scene of recycling, for example, in the refrigerator, the product is pulverized together at the recycling factory, and the glass fiber is mixed with urethane scraps and used for thermal recycling. Not good.

  For this reason, there exists a vacuum heat insulating material using the core material which processed the short fiber of polyester into the sheet form by the needle punch method like patent document 7. FIG. However, although the vacuum heat insulating material using this core material is excellent in handleability and recyclability, the thermal conductivity, which is an index representing the heat insulating performance, is about 0.0030 [W / mK], and the glass fiber is the core. Compared to the thermal conductivity of 0.0020 [W / mK] of a general vacuum heat insulating material used as a material, the heat insulating performance is inferior.

Therefore, the needle punch method in which the fibers are entangled in the thickness direction which is the heat insulation direction is not used, and the fiber orientation in the thickness direction which is the heat insulation direction is achieved by using a long fiber thermoplastic resin as in Patent Document 8. There is a processing method for suppressing the above and maintaining the form as a fiber assembly, and as one of them, there is a method of laminating a sheet-like fiber assembly obtained by hot embossing.
However, the welding location by hot embossing becomes a factor of increasing the amount of heat transfer in the thickness direction, which is the heat insulating direction.

  With respect to such an increase in the amount of heat transfer, Patent Document 8 describes that the area ratio of the welded portion by heat embossing is reduced, but it is specific other than lowering the area ratio of the welded portion. However, a method for preventing an increase in the amount of heat transfer was not shown, and depending on the basis weight (fiber weight per unit area), the heat insulation performance deteriorated (increased thermal conductivity).

  The present invention has been made to solve the above-described problems, and is a vacuum using a core material in which a fiber assembly obtained by processing a thermoplastic resin of long fibers into a sheet shape by hot embossing is laminated. Providing a vacuum heat insulating material with excellent heat insulation, handling properties, productivity, and recyclability, and a heat insulating box equipped with this vacuum heat insulating material by performing appropriate heat embossing on the heat insulating material. With the goal.

The present invention relates to a vacuum heat insulating material in which a core material is accommodated in a gas barrier container and sealed in a reduced pressure state, and the core material is formed by laminating a long-fiber aggregate of a thermoplastic resin. The aggregate is heat embossed to form a sheet, and the thickness of the heat-embossed long fiber aggregate under reduced pressure sealing is the thickness of the long fiber aggregate not subjected to hot embossing under reduced pressure sealing. 80% or more.
Moreover, the heat insulation box which concerns on this invention is equipped with an outer box and the inner box arrange | positioned inside the outer box, and arrange | positions said vacuum heat insulating material between an outer box and an inner box.

According to the present invention, the vacuum heat insulating material uses a core material formed by laminating a fiber assembly that is processed into a sheet shape by performing an appropriate hot embossing process on a long fiber thermoplastic resin. As a result, it has excellent heat insulation properties, as well as excellent handling, productivity, and recyclability.
Moreover, the heat insulation box excellent in heat insulation can be obtained.

It is a perspective view of the vacuum heat insulating material which concerns on Embodiment 1 of this invention. FIG. 2 is an exploded perspective view of FIG. 1. It is explanatory drawing which shows the lamination | stacking state of the core material of the vacuum heat insulating material of FIG. It is explanatory drawing of the long fiber assembly of the vacuum heat insulating material of FIG. It is explanatory drawing which shows the relationship between the thickness of the long-fiber assembly which has the heat embossing under pressure reduction sealing which concerns on Embodiment 1, and the thickness of the long-fiber assembly when not having a heat embossing. It is a diagram which shows the relationship between the fabric weight of the long-fiber assembly in a comparative example, and thermal conductivity. In Example 1, it is a diagram which shows the relationship between the thickness ratio at the time of pressure reduction sealing | blocking, and thermal conductivity when the basis weight is 25 g / m < ² > and clearance adjustment is performed. In Example 2, it is a diagram which shows the relationship between a fabric weight and heat conductivity when it is made for the thickness at the time of pressure reduction sealing to be 85% of the thickness when not performing a heat embossing. It is sectional drawing which shows typically the heat insulation box which concerns on Embodiment 2 of this invention.

[Embodiment 1: Vacuum heat insulating material]
As shown in FIGS. 1 and 2, the vacuum heat insulating material 4 according to Embodiment 1 of the present invention is enclosed in a gas barrier container 2 (hereinafter referred to as an outer packaging material) having air barrier properties and the outer packaging material 2. It consists of the core material 1 and the gas adsorbent 3, and the inside of the outer packaging material 2 is depressurized to a predetermined degree of vacuum.
The outer packaging material 2 of the vacuum heat insulating material 4 is made of a plastic laminate film having a gas barrier property made of nylon, aluminum vapor-deposited PET, aluminum foil, and high-density polyethylene.
As shown in FIG. 3, the core material 1 enclosed in the outer wrapping material 2 is a laminate of a plurality of sheet-like long fiber aggregates 1a. The long fiber aggregates 1a are made of thermoplastic resin long fibers. It is an aggregate.

  The material used for the core 1 of the vacuum heat insulating material 4 is a thermoplastic resin such as polyethylene terephthalate (hereinafter also referred to as PET). In addition, thermoplastic resins such as polylactic acid, polypropylene, polystyrene, and LCP (liquid crystal polymer) can be used.

Below, the structure of the core material 1 of the vacuum heat insulating material 4 is explained in full detail.
As shown in FIG. 4, the sheet-like long fiber assembly 1a constituting the core material 1 of the vacuum heat insulating material 4 was subjected to bonding processing such as hot embossing (thermal embossing portion 5) on the long fiber assembly. Is.
Then, as shown in FIG. 5, the thickness t of the hot fiber embossed long fiber assembly 1a under reduced pressure sealing (the right side of FIG. 5) is reduced in pressure by the long fiber assembly 10a that is not hot embossed. The thickness T is 80% or more (t ≧ 0.8 T) of the thickness T (left side of FIG. 5).
In this case, the thickness t of the heat-embossed long fiber assembly 1a under reduced pressure sealing is the case where the clearance of the calender roll is adjusted, the pressure is controlled, and the appropriate thickness is adjusted (FIG. (See figure on the right side of 5).
The thickness t under reduced pressure sealing (thickness at reduced pressure sealing) refers to the thickness of the vacuum heat insulating material 4 obtained by laminating a plurality of the respective long fiber assemblies 1a to form the core material 1, and the outer packaging. Except for the thickness of the material 2, it is divided by the number of laminated layers.

Thus, if the thickness t of the heat-embossed long fiber assembly 1a under reduced pressure sealing is 80% or more of the thickness T of the long fiber assembly 10a under reduced pressure sealing when not heat embossed. The deterioration of the heat insulation performance due to heat embossing can be suppressed.
Note that the thickness t under reduced pressure sealing can be arbitrarily set at 80% or more of the thickness T in the case of not performing the heat embossing, but the strength of the long fiber aggregate 1a decreases as the thickness increases. In order to ensure the desired handleability, it is desirable that the thickness be 90% or less of the thickness T.

The manufacturing method of the vacuum heat insulating material 4 comprised as mentioned above is demonstrated.
First, the manufacturing process of the long-fiber assembly 1a of the vacuum heat insulating material 4 will be described.
The long fiber aggregate 1a, which is a long fiber thermoplastic resin, can be obtained by a spunbond method.
First, polyethylene terephthalate (PET), which is a raw material, is dehumidified and dried, and then heated by an extruder to, for example, about 280 ° C. to 300 ° C. to knead and melt. The molten PET resin passes through a polymer filter for removing foreign substances, and then passes through a heater-heated pipe, and is sent to a nozzle pack by a gear pump. The nozzle pack is composed of a plurality of distribution plates, and the resin is uniformly distributed to the long nozzles. Uniformly distributed PET resin is extruded and spun from a number of holes formed in the nozzle plate at the most downstream side of the nozzle pack.

  The extruded PET resin in the form of a thread is cooled by sending cold air directly under the nozzle, and is stretched at a high speed by a stretching device using compressed air underneath to obtain a desired fiber diameter, and orientation crystallization is performed. In this case, considering the spinning stability and the heat insulation performance, the average fiber diameter is set to 10 μm, for example.

The fibers that have been stretched and oriented and crystallized are collected as they are on a mesh conveyor disposed under the stretching apparatus, and sent to a hot embossing roll. At this time, the fiber diameter and the basis weight can be changed by adjusting the extrusion amount of the PET resin and the conveyor speed.
A large number of continuous fibers collected on the mesh conveyor are heat-sealed through a sculpture roll with a dot-like pinpoint pattern heated to, for example, about 190 ° C to 230 ° C and a calender roll with a smooth surface. To obtain a heat-embossed long fiber assembly 1a. At this time, in order to obtain the long fiber aggregate 1a having a desired thickness, the clearance of the calendar roll is adjusted.

Next, the manufacturing process of the outer packaging material 2 of the vacuum heat insulating material 4 will be described.
For the outer packaging material 2 of the vacuum heat insulating material 4, for example, a plastic laminate film having a gas barrier property made of 6 μm nylon, 10 μm aluminum vapor-deposited PET, 6 μm aluminum foil, and 50 μm high-density polyethylene is used. In addition, when a laminate film that does not include an aluminum foil such as polypropylene, polyvinyl alcohol, or polypropylene is used, it is possible to suppress a decrease in heat insulation performance due to a heat bridge.

Next, the vacuum packaging process of the vacuum heat insulating material 4 will be described.
The vacuum heat insulating material 4 is manufactured by inserting the core material 1 into the outer packaging material 2 that is a bag, fixing it so that the other side of the mouth is not closed, and drying it at a temperature of, for example, 100 ° C. for 2 hours. , The gas adsorbent 3 for adsorbing the residual gas after vacuum packaging, the outgas from the core material 1 released over time, and the permeated gas entering through the sealing layer of the outer packaging material 2 is contained in the outer packaging material 2. And vacuuming is performed by, for example, a Kashiwagi type vacuum packaging machine (manufactured by NPC; KT-1600). Vacuuming is performed until the degree of vacuum in the chamber becomes, for example, about 1 Pa to 3 Pa, and the opening of the outer packaging material 2 is heat-sealed in the chamber as it is to obtain the plate-like vacuum heat insulating material 4.

  The vacuum heat insulating material 4 configured as described above uses a core material 1 formed by laminating a long fiber assembly 1a obtained by subjecting a long fiber thermoplastic resin to an appropriate heat embossing process to form a sheet. Therefore, it is excellent in heat insulation, and also in handling, productivity, and recyclability.

[Experimental example]
A vacuum heat insulating material was formed using a sheet-like long fiber aggregate obtained without adjusting the clearance of the calender roll and controlling only the pressure and not adjusting the thickness at the time of vacuum sealing. The temperature of the calendar roll was 200 ° C., the linear pressure was 20 kg / cm, and the winding speed of the sheet-like fiber assembly was 23 to 95 m / min depending on the basis weight.
The heat insulation performance of the obtained vacuum heat insulating material was measured using a thermal conductivity meter “AutoΛ HC-074 (manufactured by Eihiro Seiki Co., Ltd.)” at a temperature difference between an upper temperature of 37.7 ° C. and a lower temperature of 10.0 ° C. This was done by measuring the thermal conductivity. Note that the measurement was performed after about 24 hours from the completion of vacuum packaging.
The evaluation results of the heat insulating performance of the vacuum heat insulating material are as shown in Table 1.

As shown in Table 1, when the calender roll clearance is not adjusted and the thickness is not adjusted at the time of vacuum sealing, the thermal conductivity increases as the fiber mass per unit area increases, and the heat insulation performance deteriorates. You can see that
That is, when the basis weight was 13.1 g / m ² , the thermal conductivity was 0.0020 W / mK. At this time, the thickness at the time of vacuum sealing of the long fiber aggregate is T = 0.092 mm when there is no hot embossing, and when hot embossing is performed (clearance adjustment is not performed, thickness adjustment is No) was t ′ = 0.060 mm, and the thickness ratio (with hot embossing / without hot embossing) was t ′ / T = 65.2%. Further, when the basis weight is 17.5 g / m ² , the thermal conductivity is 0.0021 W / mK. At this time, the thickness at the time of vacuum sealing of the long fiber aggregate is T = when there is no hot embossing. 0.123 mm, when heat embossing is performed (clearance adjustment is not performed, thickness adjustment is not performed), t ′ = 0.075 mm, and thickness ratio (with heat embossing / without heat embossing) ) Was t ′ / T = 61.0%.

Further, when the basis weight is 25 g / m ² , the thermal conductivity is 0.0023 W / mK. At this time, the thickness at the time of vacuum sealing of the long fiber aggregate is T = 0. When heat embossing is performed (clearance adjustment is not performed and thickness adjustment is not performed), t ′ = 0.114 mm, and the thickness ratio (with heat embossing / without heat embossing) is t ′ / T = 65.1%. Further, when the basis weight is 53 g / m ² , the thermal conductivity is 0.0027 W / mK. At this time, the thickness at the time of vacuum sealing of the long fiber aggregate is T = 0. When heat embossing is performed (clearance adjustment is not performed and thickness adjustment is not performed), t ′ = 0.212 mm, and the thickness ratio (with heat embossing / without heat embossing) is t ′ / T = 57.1%.

These results, when subjected to hot embossing without clearance adjustment, as shown in FIG. 6, a basis weight of ^{13.1g / m 2, 17.5g / m} 2, 25g / m 2, 53g / m ^It can be seen that as the value increases to ² , the thermal conductivity increases to 0.0020 W / mK, 0.0021 W / mK, 0.0023 W / mK, 0.0027 W / mK, and the heat insulation performance deteriorates.
In both cases, the thickness (t ′) of the long-fiber assembly when heat embossing is performed (however, the clearance adjustment is not performed and the thickness is not adjusted) is as follows. When not performed, it is about 60% of the thickness (T) during reduced pressure sealing.

[Example 1]
The vacuum heat insulating material 4 was formed using the sheet-like long fiber aggregate 1a in which the basis weight was all 25 g / m ² , the calender roll clearance was adjusted, and the thickness was adjusted at the time of vacuum sealing.
The evaluation results of the heat insulating performance of the vacuum heat insulating material 4 are as shown in Table 2.

  As shown in Table 2, the thickness of the long-fiber assembly 1a when sealed under reduced pressure is T = 0.175 mm when there is no hot embossing (see the left figure in FIG. 5), and the clearance is adjusted during hot embossing. The thickness at the time of vacuum sealing is adjusted to t = 0.114 mm (see the right figure in FIG. 5), and the thickness ratio (with hot embossing / without hot embossing) is t / T = 65 %. The thermal conductivity at this time was 0.0023 W / mK. In addition, T = 0.175 mm when there is no hot embossing, clearance adjustment during hot embossing, and thickness adjustment during decompression sealing, t = 0.125 mm, thickness ratio (hot embossing) With processing / without heat embossing) was set to t / T = 71%. The thermal conductivity at this time was 0.0021 W / mK.

In addition, T = 0.175 mm when there is no hot embossing, clearance adjustment during hot embossing, and thickness adjustment during decompression sealing, t = 0.146 mm, and thickness ratio (heat embossing) With processing / without heat embossing) was set to t / T = 83%. The thermal conductivity at this time was 0.0020 W / mK. In addition, T = 0.175 mm when there is no hot embossing, clearance adjustment during hot embossing, and thickness adjustment during decompression sealing, t = 0.157 mm, thickness ratio (heat embossing) With processing / without heat embossing) was set to t / T = 90%. The thermal conductivity at this time was 0.0020 W / mK.
On the other hand, when there was no heat embossing and the thickness of the long-fiber aggregate 10a at the time of vacuum sealing was T = 0.175 mm, the thermal conductivity of the fiber aggregate was 0.0020. (See FIG. 7).

  From these results, as shown in FIG. 7, reduced pressure sealing of the long fiber aggregate 1a when heat embossing is performed (at this time, clearance adjustment is performed and thickness adjustment is performed during reduced pressure sealing). If the thickness t at the time is set to 80% or more of the reduced pressure sealing thickness T of the long fiber aggregate 10a when the hot embossing is not performed (see the left figure in FIG. 5), the heat insulation by the hot embossing is performed. It turned out that the deterioration of performance can be suppressed (refer FIG. 7).

[Example 2]
Based on the above results, the thickness t at the time of vacuum sealing of the long fiber assembly 1a when heat embossing is performed in each basis weight is the thickness of the long fiber assembly 10a when heat embossing is not performed. The sheet-like long fiber assembly 1a was manufactured so as to be 85% of T (see FIG. 5), and the heat insulating performance of the vacuum heat insulating material 4 was evaluated. The results were as shown in Table 3.

As shown in Table 3, when t / T = 85%, when the basis weight is 13.1 g / m ² , the thermal conductivity is 0.0020 W / mK and the basis weight is 17.5 g / m ^2. , The thermal conductivity is 0.0020 W / mK, when the basis weight is 25 g / m ² , the thermal conductivity is 0.0019 W / mK, and when the basis weight is 53 g / m ² , the thermal conductivity is 0.0021 W / m ^2. mK.

Experimental Example (without clearance adjustment of the long fiber aggregate, vacuum sealing thickness no adjustment during stop), as shown in FIG. 6, a basis weight of ^{13.1g / m 2, 17.5g / m} 2, It can be seen that the thermal conductivity increases (increases from 0.0020 W / mK to 0.0027 W / mK) as the values increase to 25 g / m ² and 53 g / m ^2, and the heat insulation performance deteriorates.
On the other hand, in Example 2 (clearance adjustment of the long fiber aggregate 1a is performed and the thickness adjustment at the time of sealing under reduced pressure is t / T = 85%), the basis weight is 13 as shown in FIG. .1g / m ^2, while also increasing the ^{17.5g / m 2, 25g / m} 2, 53g / m 2, almost no change in the thermal conductivity from (0.0019W / mK to 0.0021W / mK It is understood that there is no deterioration in the heat insulation performance.

  Thus, it is preferable that the thickness of the long-fiber assembly 1a at the time of vacuum sealing is arbitrarily set at 80% or more of the thickness when heat embossing is not performed, and in this case, good thermal insulation performance is achieved. It turns out that it is obtained. However, since the strength of the long fiber assembly 1a decreases as the thickness at the time of vacuum sealing increases, the thickness of the long fiber assembly 1a is 90% or less in order to ensure the desired handleability. Is desirable.

[Embodiment 2: Insulation box]
FIG. 9 is a cross-sectional view of a heat insulation box (in this embodiment, a refrigerator) according to Embodiment 2 of the present invention.
In FIG. 9, the refrigerator 20, which is a heat insulating box, includes an outer box 21, an inner box 22 disposed inside the outer box 21, a vacuum heat insulating material 4 disposed between the outer box 21 and the inner box 22, and A polyurethane foam (heat insulating material) 23 and a refrigeration unit (not shown) for supplying cold heat into the inner box 22 are provided. The outer box 21 and the inner box 22 each have an opening (not shown) formed on a common surface, and an opening / closing door (not shown) is provided in the opening.

  In the refrigerator described above, since the heat of the vacuum heat insulating material 4 may flow from the outer box 21 through the outer packaging material 2 (see FIG. 1), the vacuum heat insulating material 4 is formed by using a spacer 24 that is a resin molded product. The box 21 is disposed away from the coated steel plate. In addition, the spacer 24 is appropriately provided with holes for not inhibiting the flow so that voids do not remain in the polyurethane foam injected into the heat insulating wall in a later step.

  That is, the refrigerator 20 has a heat insulating wall 25 formed by the vacuum heat insulating material 4, the spacer 24 and the polyurethane foam 23. In addition, the range in which the heat insulation wall 25 is arrange | positioned is not limited, The whole range or one part of the clearance gap formed between the outer box 21 and the inner box 22 may be sufficient, It may be arranged inside.

When the refrigerator 20 configured as described above 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 20 has the vacuum heat insulating material 4 in which the core material 1 formed of the long fiber aggregate 1a of the thermoplastic resin is disposed, the crushing process can be performed without removing the vacuum heat insulating material 4. It does not reduce combustion efficiency or become a residue during thermal recycling, and is highly recyclable.

  The vacuum heat insulating material 4 configured as described above is a core material formed by laminating a long fiber assembly 1a obtained by subjecting a long fiber thermoplastic resin to an appropriate heat embossing process to form a sheet. 1 is used, the refrigerator 20 including the heat insulating wall 25 including the vacuum heat insulating material 4 can have a very good heat insulating property.

In the above description, the case where the heat insulating box is the refrigerator 20 has been shown, but the present invention is not limited to this, and is not limited to this. Instead of the box having the shape, a heat insulating bag (heat insulating container) having a deformable outer bag and an inner bag may be used.
In these cases, the heat insulating box may be provided with temperature adjusting means to adjust the temperature inside the inner box.

  DESCRIPTION OF SYMBOLS 1 Core material, 1a Long fiber assembly, 2 Outer packaging material, 4 Vacuum heat insulating material, 5 Hot embossing part, 10a Long fiber assembly which is not heat-embossed, 21 Outer box, 22 Inner box, 23 Heat insulating material, 24 Spacer.

Claims (9)

A vacuum heat insulating material that contains a core material inside a gas barrier container and seals the inside in a reduced pressure state,
The core material is formed by laminating a long fiber assembly of thermoplastic resin,
The long fiber aggregate is formed into a sheet by hot embossing,
A vacuum characterized in that a thickness of the hot fiber embossed long fiber aggregate under reduced pressure sealing is 80% or more of a thickness of the long fiber aggregate not subjected to hot embossing under reduced pressure sealing. Insulation.   The thickness of the long-fiber assembly subjected to hot embossing under reduced pressure sealing is 80% to 90% of the thickness of the long-fiber assembly not subjected to hot embossing under reduced pressure sealing. The vacuum heat insulating material according to claim 1.   The thickness under reduced pressure sealing of the hot fiber embossed long fiber aggregate is 85% of the thickness under reduced pressure sealing of the long fiber aggregate not subjected to hot embossing. 2. The vacuum heat insulating material according to 2.   The vacuum heat insulating material according to any one of claims 1 to 3, wherein the thickness of the hot-fiber embossed long fiber aggregate is adjusted by adjusting the clearance of a calender roll.   The vacuum heat insulating material according to any one of claims 1 to 4, wherein the long fiber aggregate is made of any one of polyethylene terephthalate, polylactic acid, polypropylene, polystyrene, and LCP. An outer box, and 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 between the outer box and the inner box.   The heat insulating box according to claim 6, wherein a heat insulating material is filled between the outer box and the vacuum heat insulating material and / or between the inner box and the vacuum heat insulating material. .   The heat insulating box according to claim 6 or 7, wherein a spacer is disposed between the outer box and the vacuum heat insulating material.   The heat insulation box according to any one of claims 6 to 8, wherein an internal temperature of the inner box is adjusted by a temperature adjusting means.

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