AU2018412205B2

AU2018412205B2 - Vacuum heat insulating material and heat insulating box

Info

Publication number: AU2018412205B2
Application number: AU2018412205A
Authority: AU
Inventors: Kazumasa Fujimura; Takayoshi MUKAIYAMA; Yuki OMORI
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2018-03-09
Filing date: 2018-03-09
Publication date: 2022-02-17
Anticipated expiration: 2038-03-09
Also published as: AU2018412205A1; WO2019171566A1; CN111801525A; TW201938373A; TWI697413B; CN111801525B; JPWO2019171566A1

Abstract

A vacuum heat-insulation material which comprises a core material for maintaining a vacuum space, an adsorbent for adsorbing moisture, and an encasing material that covers the core material and the adsorbent, the encasing material having been hermetically sealed so that the inside thereof is in a depressurized state, wherein the encasing material is configured of a surface-protective layer, a gas-barrier layer comprising at least two kinds of gas-barrier films, and a fusion-bonding layer, the at least two kinds of gas-barrier films having a difference therebetween in shrinkage through heating at 100°C for 2 hours or longer of 2% or less.

Description

Technical Field

[0001]

The present disclosure relates to a vacuum heat insulating material having a gas

barrier layer in an outer wrapping material thereof and also relates to a heat insulating

box.

Background

[0002] As a vacuum heat insulating material used as a heat insulating material for

refrigerators and other such equipment, a vacuum heat insulating material formed by

covering, with two outer wrapping materials, a core material that retains a vacuum

space and an adsorbent that adsorbs moisture and by decompression-sealing the

interior of the outer wrapping materials has been known.

[0003]

The outer wrapping materials include a surface protection layer, a gas barrier

layer, and a heat seal layer. The outer wrapping materials keep the interior of the

vacuum heat insulating material in vacuum, and as a result, the thermal conductivity of

the vacuum heat insulating material is maintained.

[0004]

A technology in which two inorganic vapor deposition films forming a gas barrier layer

are stacked together with inorganic vapor deposition surfaces thereof facing each other

in contact is disclosed in Patent Literature 1 and a technology of using a biaxially

oriented ethylene vinyl alcohol film for a vacuum heat insulating material, the film having

a dry heat shrinkage of 2% or less in the width and length directions thereof, is

disclosed in Patent Literature 2.

Patent Literature

[0005] Patent Literature 1: Japanese Unexamined Patent Application Publication No.

2012-219955

Patent Literature 2: Japanese Unexamined Patent Application Publication No.

2005-1240

[0006] In a vacuum heat insulating material, when water vapor enters the interior

thereof, the degree of vacuum decreases, the thermal conductivity increases, and, as a

result, heat insulating performance deteriorates. The pathways through which water

vapor enters the interior of the vacuum heat insulating material are probably a pathway

from a surface of outer wrapping materials and a pathway from a heat seal layer formed

by heat sealing the two outer wrapping materials.

[0007]

With the technology in Patent Literature 1, inorganic vapor deposition layers of

gas barrier films are stacked together, uneven vapor deposition is kept from occurring,

and attempts are thus made to prevent or reduce the entry of water vapor. A vacuum

heat insulating material is manufactured through a heat drying step. Thus, when the

gas barrier films shrink and vapor deposition cracking occurs, the vacuum state in the

interior of the vacuum heat insulating material is not maintained over a long period, and

the increase in thermal conductivity cannot be suppressed.

[0008]

With the technology in Patent Literature 2, the difference in the shrinkage of each

gas barrier film in the width and length directions is limited, and attempts are thus made

to prevent or reduce the occurrence of distortion during vapor deposition. However, in

the case where the difference in the shrinkage of such gas barrier films is large when

the gas barrier films shrink after a vacuum heat insulating material is subjected to a heat

drying step, vapor deposition cracking occurs. Also in this case, the vacuum state in

the interior of the vacuum heat insulating material is not maintained over a long period,

and the increase in thermal conductivity cannot be suppressed.

[0009] It is desired to address or ameliorate one or more disadvantages or limitations

associated with the prior art, or to at least provide a useful alternative.

Summary

[0010]

In one embodiment, the present invention provides a vacuum heat insulating

material comprising a core material that retains a vacuum space, an adsorbent that

adsorbs moisture, and an outer wrapping material that covers the core material and the

adsorbent, with the interior of the outer wrapping material being decompression-sealed.

The outer wrapping material is formed of a surface protection layer, a gas barrier layer

that includes at least two kinds of gas barrier films, and a heat seal layer, and a

difference in the shrinkage between the at least two kinds of gas barrier films when

heated at 100 degrees C for two hours or more is 2% or less.

[0011]

A heat insulating box according to another embodiment of the present disclosure

includes the above-described vacuum heat insulating material.

[0012]

(Deleted)

Brief Description of the Drawings

[0013] Preferred embodiments of the present invention are hereinafter described, by

way of example only, with reference to the accompanying drawings, in which:

[Fig. 1] Fig. 1 is a sectional view illustrating a schematic structure of a vacuum

heat insulating material according to Embodiment 1 of the present disclosure.

[Fig. 2] Fig. 2 is a table presenting the results of the comparison for the increase

in the thermal conductivity of vacuum heat insulating materials of samples of Example 1

according to Embodiment 1 of the present disclosure and those of Comparative

Example 1.

[Fig. 3] Fig. 3 is a graph illustrating the relationship between the water vapor

transmission rate of each outer wrapping material and the difference in the shrinkage in

Example 1 according to Embodiment 1 of the present disclosure and in Comparative

Example 1.

[Fig. 4] Fig. 4 is a table presenting the results of the comparison for the increase

in the thermal conductivity of a vacuum heat insulating material of a sample of Example

2 according to Embodiment 1 of the present disclosure.

[Fig. 5] Fig. 5 is a table presenting the results of the comparison for the increase

3 according to Embodiment 1 of the present disclosure.

[Fig. 6] Fig. 6 is a sectional view illustrating a schematic structure of a heat

insulating box according to Embodiment 2 of the present disclosure.

Detailed Description

[0013a]

At least some embodiments of the present disclosure address the above

described problems associated with known vacuum heat insulating materials, and

provide a vacuum heat insulating material and a heat insulating box where the gas

barrier properties of an outer wrapping material do not deteriorate even after a heat

drying step during manufacture and that can maintain heat insulating performance for a

long time.

[0013b]

In the vacuum heat insulating material according to one embodiment of the

present disclosure and the heat insulating box according to another embodiment of the

present disclosure, the difference in the shrinkage between the at least two kinds of gas

barrier films when heated at 100 degrees C for two hours or more is 2% or less. Thus, after a heat drying step during manufacture, the difference in the shrinkage amount

between the at least two kinds of gas barrier films does not turn out to be excessively

large, and the occurrence of vapor deposition cracking or a similar defect is prevented

or reduced. As a result, the gas barrier properties of the outer wrapping material do

not deteriorate even after the heat drying step during manufacture, and heat insulating

performance can be maintained for a long time.

[0014]

Hereinbelow, Embodiments of the present disclosure will be described on the

A basis of the drawings. In each of the drawings, components denoted by the same references correspond to the same components or equivalents thereof, and this applies throughout the specification. In the drawings of sectional views, the hatching is omitted where appropriate in view of clarity. Forms of the components described throughout the specification are merely examples, and are not limited to those set forth herein.

[0015]

An~

UUU4- I %J

KPO-3742 Embodiment 1

Fig. 1 is a sectional view illustrating a schematic structure of a vacuum heat

insulating material 1 according to Embodiment 1 of the present disclosure. In the

drawings below including Fig. 1, the size relationship between, the shape of, or a similar

feature of individual components may be different from actual ones. The specific size or other features of individual components should be judged with reference to the

following description.

[0016] As illustrated in Fig. 1, the vacuum heat insulating material 1 is a heat insulating

material that achieves low thermal conductivity by evacuating the interior thereof. The

vacuum heat insulating material 1 as a whole has a substantially rectangular flat shape.

The vacuum heat insulating material 1 includes a core material 2, an adsorbent 3, and

an outer wrapping material 4.

[0017]

The core material 2 retains a vacuum space. The adsorbent 3 adsorbs at least

moisture. The outer wrapping material 4 covers the core material 2 and the adsorbent

3.

[0018]

The vacuum space in the interior that is sealed by the outer wrapping material 4

is decompressed through an opening port thereof. The opening port is heat sealed

through, for example, heat sealing. The interior of the outer wrapping material 4 is thus

decompression-sealed.

[0019]

The core material 2 is used to retain a vacuum space. A fiber assembly such as

glass wool is generally used as the core material 2. Furthermore, the fiber assembly

forming the core material 2 may be one that is heat and pressure-molded, one that is

sealed with an inner wrapping material, or one that is bound with a binder.

[0020]

UUU4- I %J

KPO-3742 <Structure of Adsorbent 3>

The adsorbent 3 adsorbs water vapor in the interior of the vacuum heat insulating material 1 and retains the degree of vacuum in the interior of the vacuum heat insulating

material 1 to thereby suppress the increase in the heat transfer coefficient. Calcium

oxide is used as the adsorbent 3. Calcium oxide may be abbreviated as CaO.

[0021]

The outer wrapping material 4 is formed of two stacked films each having a

multilayer structure of a surface protection layer 41, a gas barrier layer 42, and a heat

seal layer 43. In the outer wrapping material 4, the heat seal layers 43 of the stacked

films are heat sealed to each other and joined together in a sealing section 43a to

thereby cover the core material 2 and the adsorbent 3. At this time, the sealing section

43a is heat sealed with the interior of the outer wrapping material 4 decompressed to a

vacuum degree of about 1 to 3 Pa (Pascals) to thereby decompression-seal the interior

of the outer wrapping material 4.

[0022]

In the outer wrapping material 4, the heat seal layers 43 may each have a

different thickness. As the outer wrapping material 4 covering the core material 2 and

the adsorbent 3, two outer wrapping materials 4 or one folded outer wrapping material 4

may be used. The number of the outer wrapping material 4 is not limited as long as

the outer wrapping material 4 can decompression-seal the core material 2 and

adsorbent 3.

[0023]

The surface protection layer 41 has a film thickness of, for example, 25 Pm. The material for the surface protection layer 41 is preferably, for example, a thermoplastic

resin having a melting point of 150 degrees C or more and excellent scratch resistance.

For example, oriented polyamide such as oriented nylon, polyethylene terephthalate,

oriented polypropylene, or a similar material can be used. Oriented nylon may be

abbreviated as ONY. Polyethylene terephthalate may be abbreviated as PET.

UUU4- I %J

KPO-3742 Oriented polypropylene may be abbreviated as OPP.

[0024]

A thermoplastic resin having excellent water vapor barrier properties and air

barrier properties is selected as the material for the gas barrier layer 42. The gas

barrier layer 42 is, for example, formed by stacking two gas barrier films having a film

thickness of 12 pm. The gas barrier layer 42 preferably includes at least two kinds of gas barrier films. That is, the gas barrier layer 42 may not only be formed by stacking

two gas barrier films of two kinds but may also be formed by stacking three or more gas

barrier films of two kinds or three or more kinds.

[0025]

As the material for the gas barrier layer 42, inorganic vapor deposition

polyethylene terephthalate, inorganic vapor deposition ethylene vinyl alcohol, or among

them, for example, a combination of two kinds of the foregoing gas barrier films with the

difference in the shrinkage therebetween when each is heated at 100 degrees C for two

hours being 2% or less can be used. The gas barrier layer 42 is formed of two gas

barrier films bonded together with surfaces thereof facing each other, the surfaces

having inorganic vapor deposition applied thereto. When the gas barrier layer 42 is

formed of three or more gas barrier films, inorganic vapor deposition may be applied to

the front and rear surfaces of one or more of the gas barrier films sandwiched by the

others, and three or more gas barrier films may be bonded together with these inorganic

vapor deposition surfaces facing each other. The inorganic material that is vapor

deposited on a thermoplastic resin is not limited to aluminum and may be alumina,

silica, or a combination of the foregoing. Ethylene vinyl alcohol may be abbreviated as

EVOH.

[0026]

Each gas barrier film was cut into a square piece having a length of 250 mm, and

the shrinkage was calculated on the basis of a dimensional change of each square

piece after being dried at 100 degrees C for two hours. The shrinkage is a fixed value

regardless of changes in the size of each gas barrier film.

UUU4- I %J

KPO-3742

[0027]

The heat seal layer 43 has a film thickness of, for example, 30 Pm. A thermoplastic resin having a melting point of 150 degrees C or less, for example, is

selected as the material for the heat seal layer 43. However, the material for the heat

seal layer 43 is not particularly specified. For example, low-density polyethylene, linear

low-density polyethylene, or a similar material is used as the heat seal layer 43. High

density polyethylene or cast polypropylene having high modulus of elasticity and

excellent water vapor barrier properties is more preferable for the heat seal layer 43.

Low-density polyethylene may be abbreviated as LDPE. Linear low-density

polyethylene may be abbreviated as LLDPE. High-density polyethylene may be

abbreviated as HDPE. Cast polypropylene may be abbreviated as CPP. In the

following description, the acronyms will be provided in parentheses.

[0028]

Even in the case where the stacked films are in the vacuum heat insulating material 1 that is yet to be evacuated and have at least three sides thereof being heat

sealed, when heat drying is performed at 100 degrees C for two hours or more, the

difference in the shrinkage between the gas barrier films forming the gas barrier layer

42 is preferably 2% or less.

[0029]

In steps of manufacturing the vacuum heat insulating material 1, first, the core material 2 is covered with the outer wrapping material 4 having a multilayer structure of

the surface protection layer 41, the gas barrier layer 42, and the heat seal layer 43.

Next, the drying of the core material 2 and the outer wrapping material 4 is performed.

The core material 2 covered with the outer wrapping material 4 is heat treated at 100

degrees C for two hours or more, and thereby moisture is removed from the core

material 2 and the outer wrapping material 4. The difference in the shrinkage between

the at least two or more layers of gas barrier films forming the gas barrier layer 42 after

heat treatment is 2% or less. Thus, the occurrence of cracking in inorganic vapor

A

UUU4- I %J

KPO-3742 deposition surfaces can be prevented or reduced, gas barrier properties do not

deteriorate, and heat insulating performance can be maintained for a long time.

[0030] The adsorbent 3 is then disposed between the core material 2 and the outer

wrapping material 4. Subsequently, the interior of the outer wrapping material 4 is

decompressed to a vacuum degree of about 1 to 3 Pa, the opening port of the outer

wrapping material 4 is heat sealed in this decompression state through, for example,

heat sealing, and the interior of the outer wrapping material 4 is decompression-sealed.

[0031]

In the vacuum heat insulating material 1 obtained through the above-described

steps, after heat treatment, the difference in the shrinkage between the at least two

kinds of gas barrier films forming the gas barrier layer 42, the gas barrier films being

bonded together with inorganic vapor deposition surfaces thereof facing each other, is

2% or less. Thus, the occurrence of cracking in inorganic vapor deposition layers can

be prevented or reduced, the degree of vacuum in the interior of the vacuum heat

insulating material 1 is maintained, and an increase in thermal conductivity is kept

suppressed over a long period.

[0032]

The vacuum heat insulating material 1 according to Embodiment 1 was produced, and Examples were compared with Comparative Examples. Hereafter, the results of

comparison will be described.

[0033]

Example 1

In Example 1, aluminum vapor deposition ethylene vinyl alcohol (EVOH) and

silica vapor deposition oriented nylon (ONY) were used as the two gas barrier films

forming the gas barrier layer 42 of the outer wrapping material 4 in the vacuum heat

insulating material 1. Furthermore, the relationships of the difference in the shrinkage

between silica vapor deposition oriented nylon (ONY) and aluminum vapor deposition

ethylene vinyl alcohol (EVOH) with the water vapor transmission rate of the outer

Q

UUU4- I %J

KPO-3742 wrapping material 4 and with the increase in the thermal conductivity of the vacuum

heat insulating material 1 were studied.

[0034]

As the surface protection layer 41 of the outer wrapping material 4, oriented nylon

(ONY) having a film thickness of 25 pm was used. As the gas barrier layer 42, silica

vapor deposition oriented nylon (ONY) having a film thickness of 12 Pm and aluminum

vapor deposition ethylene vinyl alcohol (EVOH) having a film thickness of 12 Pm bonded together, with the inorganic vapor deposition surfaces of both facing each other,

were used. As the heat seal layer 43, cast polypropylene (CPP) having a film

thickness of 30 pm was used. The core material 2 for the vacuum heat insulating material 1 was formed of glass wool.

[0035]

Stacked films where the above-specified surface protection layer 41, gas barrier

layer 42, and heat seal layer 43 were stacked were used as the outer wrapping material

4. The core material 2 was covered with the outer wrapping material 4 to produce the

vacuum heat insulating material 1.

[0036]

To determine the water vapor transmission rate, after the outer wrapping material 4 was dried at 100 degrees C for two hours or more, the water vapor transmission rate

of a piece of each stacked film forming the outer wrapping material 4 under conditions

of 40 degrees C and an RH of 90% was studied. For measurement, a GTR

1000XAMD manufactured by GTR TEC Corporation was used.

[0037]

To determine the increase in the thermal conductivity, the thermal conductivity of the vacuum heat insulating material 1 immediately after manufacture and the thermal

conductivity of the vacuum heat insulating material 1 after storage in an atmosphere of

a temperature of 30 degrees C and a relative humidity of 60% for 30 days were studied,

and the difference therebetween was calculated as the increase.

[0038]

As samples of Example 1, the vacuum heat insulating materials 1 each including

in

UUU4- I %J

KPO-3742 the gas barrier layer 42 that included the aluminum vapor deposition ethylene vinyl

alcohol (EVOH) having a film thickness of 12 pm and the silica vapor deposition

oriented nylon (ONY) having a film thickness of 12 pm and a shrinkage differing from the shrinkage of the aluminum vapor deposition ethylene vinyl alcohol (EVOH) by less

than 2% were used.

[0039]

In samples of Comparative Example 1, for the gas barrier layers 42 of the outer wrapping materials 4 in the vacuum heat insulating materials 1, the silica vapor

deposition oriented nylons (ONY) having a film thickness of 12 Pm and a shrinkage differing from the shrinkage of the aluminum vapor deposition ethylene vinyl alcohol

(EVOH) by 2.2% and by 2.3% were used. The other structures and conditions were

the same as the samples of Example 1.

[0040]

Fig. 2 is a table presenting the results of the comparison between the increase in

the thermal conductivity of the vacuum heat insulating materials 1 of the samples of

Example 1 according to Embodiment 1 of the present disclosure and Comparative

Example 1. Fig. 3 is a graph illustrating the relationship between the water vapor

transmission rate of each outer wrapping material 4 and the difference in the shrinkage

in Example 1 according to Embodiment 1 of the present disclosure and in Comparative

Example 1.

[0041]

As presented in Figs. 2 and 3, the shrinkage of each gas barrier film after heat

drying at 100 degrees C for two hours resulted as follows. The aluminum vapor

deposition ethylene vinyl alcohol film had a shrinkage of 2.6%. The silica vapor

deposition oriented nylon films of the samples of Example 1 had shrinkages of 1.2%

and 0.8%. The silica vapor deposition oriented nylon films of the samples of

Comparative Example 1 had shrinkages of 0.4% and 0.2%.

[0042]

Furthermore, the water vapor transmission rate of stacked films that each

included the gas barrier layer 42 including one or the other of the silica vapor deposition

UUU4- I %J

KPO-3742 oriented nylon films and the aluminum vapor deposition ethylene vinyl alcohol film of the 2 2 samples of Example 1 was 2.4mg/(m day) and 2.5mg/(m day). Thewatervapor transmission rate of stacked films that each included the gas barrier layer 42 including

one or the other of the silica vapor deposition oriented nylon films and the aluminum

vapor deposition ethylene vinyl alcohol film of the sample of Comparative Example 1

was 7.7 mg/(m 2.day) and 9.6 mg/(m 2 day).

[0043]

The results revealed that, when the silica vapor deposition oriented nylon film had

a shrinkage differing from the shrinkage of the aluminum vapor deposition ethylene vinyl

alcohol film by more than 2%, the water vapor transmission rate tended to drastically

increase. As indicated in Fig. 3, a graph where the horizontal axis corresponds to the

difference in the shrinkage and the vertical axis corresponds to the water vapor

transmission rate is used. In Fig. 3, the water vapor transmission rate of 2.4

mg/(m2 day) in one of the samples of Example 1 in Fig. 2 is plotted as "a", the water

vapor transmission rate of 2.5 mg/(m 2 .day) in the other of the samples of Example 1 in

Fig. 2 is plotted as "b", the water vapor transmission rate of 7.7mg/(m 2.day) in one of the samples of Comparative Example 1 in Fig. 2 is plotted as "c", and the water vapor

transmission rate of 9.6 mg/(m 2 .day) in the other of the samples of Comparative Example 1 in Fig. 2 is plotted as "d". These points "a" to "d" were connected and

compared with the difference in the shrinkage. The results indicate that, when the

location at which the difference in the shrinkage is 2% is estimated as an inflection

point, in the case where the difference in the shrinkage is 2% or less from the inflection

point, a low water vapor transmission rate is moderately maintained far from the

inflection point. On the other hand, in the case where the difference in the shrinkage

exceeds 2%, moving beyond the inflection point, which is the location at which the

difference in the shrinkage is 2%, the water vapor transmission rate drastically

increases. Thus, the location at which the difference in the shrinkage is 2% can be

considered as an inflection point and as being of critical importance.

[0044]

As presented in Fig. 2, the thermal conductivity of the vacuum heat insulating

UUU4- I %J

KPO-3742 materials 1 of Example 1 and Comparative Example 1 immediately after production was

1.8mW/(m.K). The increase in the thermal conductivity of the vacuum heat insulating materials 1 of Example 1 after storage in an atmosphere of a temperature of 30 degrees

C and a relative humidity of 60% for 30 days was 0.6 mW/(m.K) and 0.7 mW/(m.K). The thermal conductivity of the vacuum heat insulating materials 1 of Comparative

Example 1 after storage in an atmosphere of a temperature of 30 degrees C and a

relative humidity of 60% for 30 days was 1.1 mW/(m.K) and 1.2 mW/(m.K).

[0045]

The above-described results revealed that when the silica vapor deposition

oriented nylon film has a shrinkage differing from the shrinkage of the aluminum vapor

deposition ethylene vinyl alcohol film by more than 2%, the increase in the thermal

conductivity tends to drastically increase.

[0046]

As described above, when silica vapor deposition oriented nylon (ONY) having a shrinkage differing from the shrinkage of aluminum vapor deposition ethylene vinyl

alcohol (EVOH) by 2% or less after heat drying at 100 degrees C for two hours, as

exemplified by Example 1, was used, good results were obtained. That is, even after

the heat drying step, high gas barrier properties were able to be maintained and the

increase in the heat transfer coefficient was able to be kept small over a long period.

[0047]

Example 2.

In Example 2, aluminum vapor deposition ethylene vinyl alcohol (EVOH) and

silica vapor deposition polyethylene terephthalate (PET) forming the two gas barrier

films that formed the gas barrier layer 42 of the outer wrapping material 4 in the vacuum

heat insulating material 1 were used. The water vapor transmission rate of the outer

wrapping material 4 and the increase in the thermal conductivity of the vacuum heat

insulating material 1 of Example 2 were compared with the water vapor transmission

rate of the outer wrapping material 4 and the increase in the thermal conductivity of the

vacuum heat insulating materials 1 of the samples of Example 1.

[0048]

UUU4- I %J

KPO-3742 As the surface protection layer 41 of the outer wrapping material 4, oriented nylon

(ONY) having a film thickness of 25 pm was used. As the gas barrier layer 42, silica vapor deposition polyethylene terephthalate (PET) having a film thickness of 12 Pm and aluminum vapor deposition ethylene vinyl alcohol (EVOH) having a film thickness of 12

pm bonded together, with the inorganic vapor deposition surfaces of both facing each other, were used. As the heat seal layer 43, cast polypropylene (CPP) having a film

[0049]

vacuum heat insulating material 1.

[0050] To determine the increase in the thermal conductivity, the thermal conductivity of

the vacuum heat insulating material 1 immediately after manufacture and the thermal

and the difference therebetween was calculated as the increase.

[0051] As a sample of Example 2, the vacuum heat insulating material 1 including the

gas barrier layer 42 that included the aluminum vapor deposition ethylene vinyl alcohol

(EVOH) having a film thickness of 12 pm and the silica vapor deposition polyethylene

terephthalate (PET) having a film thickness of 12 pm and a shrinkage differing from the shrinkage of the aluminum vapor deposition ethylene vinyl alcohol (EVOH) by less than

2% was used.

[0052] Fig. 4 is a table presenting the results of the comparison with the increase in the

thermal conductivity of the vacuum heat insulating material 1 of the sample of Example

2 according to Embodiment 1 of the present disclosure.

1A

UUU4- I %J

KPO-3742

[0053] As presented in Fig. 4, the shrinkage of each gas barrier film after heat drying at

100 degrees C for two hours resulted as follows. The shrinkage of the aluminum vapor

deposition ethylene vinyl alcohol film was 2.6%. The shrinkage of the silica vapor

deposition polyethylene terephthalate film of the sample of Example 2 was 1.4%. The

water vapor transmission rate of stacked films that each included the gas barrier layer

42 including the silica vapor deposition polyethylene terephthalate film and the

aluminum vapor deposition ethylene vinyl alcohol film of the sample of Example 2 was

2.2 mg/(m2-day). The thermal conductivity of the vacuum heat insulating material 1 of

Example 2 immediately after production was 1.8 mW/(m.K). The increase in the thermal conductivity of the vacuum heat insulating material 1 of Example 2 after storage

in an atmosphere of a temperature of 30 degrees C and a relative humidity of 60% for

days was 0.5 mW/(m.K).

[0054] In Example 2, in contrast to Example 1 of Fig. 2, a polyethylene terephthalate film

having a lower water vapor transmission rate than oriented nylon was used as a base

material. As a result, in Example 2, gas barrier properties higher than in Example 1

were able to be maintained and the increase in the heat transfer coefficient was able to

be kept small over a longer period than in Example 1.

[0055] Example 3.

In Example 3, aluminum vapor deposition ethylene vinyl alcohol (EVOH) and

alumina vapor deposition polyethylene terephthalate (PET) forming the two gas barrier

films that formed the gas barrier layer 42 were used. The water vapor transmission

vacuum heat insulating material 1 of Example 3 were compared with the water vapor

transmission rate of the outer wrapping material 4 and the increase in the thermal

conductivity of the vacuum heat insulating material 1 of the sample of Example 2.

[0056]

UUU4- I %J

KPO-3742 (ONY) having a film thickness of 25 pm was used. As the gas barrier layer 42, alumina

vapor deposition polyethylene terephthalate (PET) having a film thickness of 12 Pm and aluminum vapor deposition ethylene vinyl alcohol (EVOH) having a film thickness of 12

[0057] Stacked films where the above-specified surface protection layer 41, gas barrier

vacuum heat insulating material 1.

[0058]

and the difference therebetween was calculated as the increase.

[0059] As a sample of Example 3, the vacuum heat insulating material 1 including the

(EVOH) having a film thickness of 12 pm and the alumina vapor deposition polyethylene

2% was used.

[0060]

Fig. 5 is a table presenting the results of the comparison with the increase in the

3 according to Embodiment 1 of the present disclosure.

[0061]

1s

UUU4- I %J

KPO-3742 As presented in Fig. 5, the shrinkage of each gas barrier film after heat drying at

deposition ethylene vinyl alcohol film was 2.6%. The shrinkage of the alumina vapor deposition polyethylene terephthalate film of the sample of Example 3 was 1.2%. The

42 including the alumina vapor deposition polyethylene terephthalate film and the

aluminum vapor deposition ethylene vinyl alcohol film of the sample of Example 3 was 1.9 mg/(m 2.day). The thermal conductivity of the vacuum heat insulating material 1 of

Example 3 immediately after production was 1.8 mW/(m.K). The increase in the thermal conductivity of the vacuum heat insulating material 1 of Example 3 after storage

days was 0.3 mW/(m.K).

[0062]

In Example 3, in contrast to Example 2 of Fig. 4, alumina having a lower water

vapor transmission rate than silica was used for vapor deposition. As a result, in

Example 3, gas barrier properties higher than in Example 2 were able to be maintained

and the increase in the heat transfer coefficient was able to be kept small over a longer

period than in Example 2.

[0063]

According to Embodiment 1, a vacuum heat insulating material 1 is formed of a core material 2 that retains a vacuum space. The vacuum heat insulating material 1

includes an adsorbent 3 that adsorbs moisture. The vacuum heat insulating material 1

includes an outer wrapping material 4 that covers the core material 2 and the adsorbent

3. The vacuum heat insulating material 1 decompression-seals the interior of the outer

wrapping material 4. The outer wrapping material 4 is formed of a surface protection

layer 41, a gas barrier layer 42 that includes at least two kinds of gas barrier films, and a

heat seal layer 43. The difference in the shrinkage between the at least two kinds of

gas barrier films when heated at 100 degrees C for two hours or more is 2% or less.

[0064]

UUU4- I %J

KPO-3742 With this structure, after a heat drying step during manufacture, the difference in

the shrinkage amount between the at least two kinds of gas barrier films does not turn

out to be excessively large. That is, after the heat drying step during manufacture, vapor deposition cracking or a similar defect in inorganic vapor depositions on the gas

barrier layer 42 is less likely to occur. As a result, gas barrier properties do not

deteriorate. Thus, the degree of vacuum in the interior of the vacuum heat insulating

material 1 is maintained, and the increase in the heat transfer coefficient can be

suppressed. Accordingly, even after the heat drying step during manufacture, the gas

barrier properties of the outer wrapping material 4 do not deteriorate, and heat

insulating performance can be maintained for a long time.

[0065]

According to Embodiment 1, the gas barrier layer 42 is formed of the at least two kinds of gas barrier films bonded together with surfaces thereof facing each other, the

surfaces having inorganic vapor deposition applied thereto.

[0066]

With this structure, after a heat drying step during manufacture, vapor deposition

cracking in inorganic vapor depositions on the gas barrier layer 42 that have surfaces

bonded together facing each other is less likely to occur. As a result, gas barrier

properties do not deteriorate. Thus, the degree of vacuum in the interior of the vacuum

heat insulating material 1 is maintained, and the increase in the heat transfer coefficient

can be suppressed.

[0067]

According to Embodiment 1, the gas barrier layer 42 is formed of ethylene vinyl alcohol (EVOH) with inorganic vapor deposition applied thereto and oriented nylon

(ONY) with inorganic vapor deposition applied thereto.

[0068]

With this structure, after the heat drying step during manufacture, the difference

in the shrinkage between the two kinds of gas barrier films is small. Thus, vapor

deposition cracking in inorganic vapor depositions on the gas barrier layer 42 is less

likely to occur. As a result, gas barrier properties do not deteriorate. Thus, the

1A

UUU4- I %J

KPO-3742 degree of vacuum in the interior of the vacuum heat insulating material 1 is maintained,

and the increase in the heat transfer coefficient can be suppressed.

[0069]

According to Embodiment 1, the gas barrier layer 42 is formed of ethylene vinyl alcohol (EVOH) with inorganic vapor deposition applied thereto and polyethylene

terephthalate (PET) with inorganic vapor deposition applied thereto.

[0070]

With this structure, after the heat drying step during manufacture has been

performed, the difference in the shrinkage between the two kinds of gas barrier films

turns out to be small. Thus, vapor deposition cracking in inorganic vapor depositions

on the gas barrier layer 42 is less likely to occur. As a result, gas barrier properties do

not deteriorate. Thus, the degree of vacuum in the interior of the vacuum heat

insulating material 1 is maintained, and the increase in the heat transfer coefficient can

be suppressed.

[0071]

According to Embodiment 1, the material that is inorganic-vapor-deposited is aluminum, alumina, silica, or a combination thereof.

[0072]

With this structure, after the heat drying step during manufacture, vapor

likely to occur.

[0073]

Embodiment 2

Fig. 6 is a sectional view illustrating a schematic structure of a heat insulating box

100 according to Embodiment 2 of the present disclosure. The heat insulating box 100

is provided in, for example, a refrigerator, a refrigeration apparatus, or other such

equipment that desirably exhibits heat insulating performance over a long period.

[0074]

As illustrated in Fig. 6, the heat insulating box 100 includes an inner box 110 and

an outer box 120. The vacuum heat insulating material 1 described in Embodiment 1

1Q

UUU4- I %J

KPO-3742 is disposed in spaces between the inner box 110 and the outer box 120. The vacuum

heat insulating material 1, being positioned between the inner box 110 and the outer

box 120, performs heat insulation. The vacuum heat insulating material 1 is

positioned, for example, at a location in close contact with outer wall surfaces of the

inner box 110. The vacuum heat insulating material 1 is preferably positioned at a

location at which heat insulation between the inner box 110 and the outer box 120 can

be performed.

[0075]

As in the above-described structure, the vacuum heat insulating material 1 having low thermal conductivity is disposed in the heat insulating box 100. Thus, a state of

low thermal conductivity between the inner box 110 and the outer box 120 is

maintained. As a result, the heat insulating performance of the heat insulating box 100

can be maintained over a long period. With a refrigerator, a refrigeration apparatus, or

other such equipment that includes the heat insulating box 100, a reduction in power

consumption is facilitated.

[0076]

The vacuum heat insulating material 1 exhibits high heat insulating performance compared with, for example, a foamed urethane heat insulating material 130. Thus, with the heat insulating box 100, higher heat insulating performance can be achieved as

compared with a heat insulating box using only the foamed urethane heat insulating

material 130. Among the spaces between the inner box 110 and the outer box 120, a

portion other than the locations at which the vacuum heat insulating material 1 is

disposed may be filled with the foamed urethane heat insulating material 130.

[0077]

In the description above, the vacuum heat insulating material 1 of the heat

insulating box 100 is in close contact with outer wall surfaces of the inner box 110.

However, the vacuum heat insulating material 1 may be in close contact with inner wall

surfaces of the outer box 120. The vacuum heat insulating material 1 may be disposed

in spaces between the inner box 110 and the outer box 120 in such a manner that no

close contact with the inner box 110 or with the outer box 120 is made by using, for

9n

UUU4- I %J

KPO-3742 example, a spacer.

[0078]

In the above description, illustrations and descriptions of portions equivalent to

portions of heat insulating boxes used in common refrigerators or other such equipment

are omitted.

[0079]

According to Embodiment 2, a heat insulating box 100 includes the above described vacuum heat insulating material 1.

[0080] With this structure, even after a heat drying step during manufacture, the gas

barrier properties of the outer wrapping material 4 do not deteriorate in the vacuum heat

insulating material 1, and heat insulating performance can be maintained for a long time

in the heat insulating box 100 including the above-described vacuum heat insulating

material 1.

[0081] <Others>

It is to be noted that the vacuum heat insulating material 1 of the present

disclosure is not limited to the Embodiments described above, that various modifications

are possible, and that the Embodiments or Examples described above may be

implemented in combination with each other.

[0082]

For example, the above description exemplifies the drying of the core material 2 and the outer wrapping material 4 performed through heat treatment at 100 degrees C

for two hours in a step for manufacturing. However, the temperature and time duration

for heat treatment are not limited thereto as long as the moisture of the core material 2

and the outer wrapping material 4 can be removed with the temperature and time

duration.

[0083]

The drying of the core material 2 and the outer wrapping material 4 is performed with the core material 2 being covered with the outer wrapping material 4. However, it is also possible to perform the drying of the core material 2 and the outer wrapping material 4 separately and then cover the core material 2 with the outer wrapping material 4.

[0084]

In the manufacturing step of the vacuum heat insulating material 1 according to

Embodiment 1 described above, the adsorbent 3 is disposed between the core material

2 and the outer wrapping material 4 after the drying of the core material 2 and the outer

wrapping material 4. However, the adsorbent 3 may be disposed before the drying of

the core material 2 and the outer wrapping material 4.

[0085]

In Embodiment 2 described above, the structure where the vacuum heat

insulating material 1 is used in the heat insulating box 100 of a refrigerator including a

cooling energy source is exemplified. However, the present disclosure is not limited

thereto. The vacuum heat insulating material 1 can be used in heat insulating boxes of

heat retaining cabinets that include a heating energy source or in heat insulating boxes

that do not include a cooling energy source or a heating energy source, namely, cooler

boxes or other such items. The vacuum heat insulating material 1 can not only be

used in the heat insulating box 100 but can also be used as a heat insulator for heating

or cooling equipment such as air-conditioning apparatuses, vehicle air conditioners, and

hot water supplies. The vacuum heat insulating material is not in a predetermined form

and can be used in heat insulating bags, heat insulating containers, or other such items

that include flexible inner and outer bags.

[0086] Throughout this specification and the claims which follow, unless the context

requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or

group of integers or steps but not the exclusion of any other integer or step or group of

integers or steps.

[0087] The reference in this specification to any prior publication (or information derived

from it), or to any matter which is known, is not, and should not be taken as an

acknowledgment or admission or any form of suggestion that that prior publication (or

information derived from it) or known matter forms part of the common general

knowledge in the field of endeavour to which this specification relates.

Reference Signs List

[0088]

1 vacuum heat insulating material 2 core material 3 adsorbent 4 outer wrapping material 41 surface protection layer 42 gas barrier layer 43 heat seal

layer 43a sealing section 100 heat insulating box 110 inner box 120 outer

box 130 foamed urethane heat insulating material

Claims

THE CLAIMS DEFINING THE INVENTION AREAS FOLLOWS:

[Claim 1] A vacuum heat insulating material, comprising:

a core material that retains a vacuum space,

an adsorbent that adsorbs moisture, and

an outer wrapping material that covers the core material and the adsorbent

with an interior of the outer wrapping material being decompression-sealed,

wherein

the outer wrapping material is formed of a surface protection layer, a gas barrier

layer that includes at least two kinds of gas barrier films, and a heat seal layer, and

a difference in a shrinkage between the at least two kinds of gas barrier films

when heated at 100 degrees C for two hours or more is 2% or less.
[Claim 2]

The vacuum heat insulating material of claim 1, wherein the gas barrier layer is

formed of the at least two kinds of gas barrier films bonded together with surfaces

thereof facing each other, the surfaces having inorganic vapor deposition applied

thereto.
[Claim 3]

The vacuum heat insulating material of claim 1 or 2, wherein the gas barrier layer

is formed of ethylene vinyl alcohol (EVOH) with inorganic vapor deposition applied

thereto and oriented nylon (ONY) with inorganic vapor deposition applied thereto.
[Claim 4]

The vacuum heat insulating material of claim 1 or 2, wherein the gas barrier layer

is formed of ethylene vinyl alcohol (EVOH) with inorganic vapor deposition applied

thereto and polyethylene terephthalate (PET) with inorganic vapor deposition applied

thereto.
[Claim 5]

The vacuum heat insulating material of any one of claims 2 to 4, wherein an

inorganic material that is inorganic-vapor-deposited through the inorganic vapor

9A deposition is aluminum, alumina, silica, or a combination thereof.
[Claim 6]

A heat insulating box comprising the vacuum heat insulating material of any one

of claims 1 to 5.