TW201719068A - Vacuum heat insulation material and heat insulation box - Google Patents

Abstract

This vacuum heat insulation material is provided with a core material holding a vacuum space, an adsorbent that adsorbs moisture, and an outer packaging material that covers the core material and the adsorbent; and the inside of the outer packaging material is depressurized and hermetically sealed. The outer packaging material is composed of a surface protective layer, a gas barrier layer and a thermal fusion layer. The outer packaging material has a sealed part obtained by thermally fusing thermal fusion layers with each other in the peripheral portion of the outer packaging material. The thermal fusion layer has a thickness from 35 [mu]m to 70 [mu]m (inclusive). The adsorbent contains calcium oxide having a moisture absorption rate of from 15 wt%/h to 32 wt%/h (inclusive).

Description

Vacuum insulation material and heat insulation box

The present invention relates to a vacuum heat insulating material used for a heat insulating box of a refrigerator or the like, and a heat insulating box using a vacuum heat insulating material.

A conventional vacuum heat insulating material used as a heat insulating material for a refrigerator or the like is formed by coating a core material that holds a vacuum space together with an adsorbent that adsorbs water vapor by two sheets of outer covering material, and sealing it under reduced pressure. The outer covering material is composed of a surface protective layer, a barrier layer and a heat fusion layer, and the heat conductivity of the vacuum heat insulating material is reduced by maintaining a vacuum inside the outer covering material. The outer covering material is proposed, for example, in Patent Document 1, and a linear low-density polyethylene film having a thickness of 50 μm or the like is used in order to prevent breakage of the bag due to pinholes. Further, for example, in Patent Document 2, in order to realize the internal vacuum state, the moisture absorption rate of the adsorbent that adsorbs water vapor is, for example, 13.2 wt%/h of calcium oxide.

Advanced technical literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2006-38122

Patent Document 2: Japanese Laid-Open Patent Publication No. 2015-59642

In the vacuum heat insulating material, it is generally considered that the intrusion path in which the water vapor intrudes into the inside is a heat fusion layer formed by the surface of the outer covering material and the two outer covering materials. As disclosed in Patent Document 1, it is expected that when the film thickness of the heat fusion layer is increased by, for example, 50 μm, the path of water vapor intrusion is enlarged, so that the amount of water vapor intruding inside is increased. In such a case, even if it is possible to suppress the breakage of the pinhole, the amount of water vapor that can enter from the fused heat fusion layer increases, so that the vacuum state inside the vacuum heat insulating material cannot be maintained for a long time without It is possible to suppress an increase in thermal conductivity.

In addition, the moisture absorption rate of the adsorbent of the patent document 2 is 13.2% by weight/h, so that both the water vapor intruding from the heat fusion layer and the water vapor invaded from the defect portion in the barrier layer are adsorbed at the same time. Not enough speed. Also in this case, it is difficult to suppress the increase in the thermal conductivity of the vacuum heat insulating material for a long period of time.

An object of the present invention is to solve the above problems and to provide a vacuum heat insulating material and a heat insulating box, which can suppress the breakage of the core material by piercing the pinhole, and can maintain the heat insulating performance for a long period of time.

The vacuum heat insulating material of the present invention comprises: a core material to maintain a vacuum space; an adsorbent to adsorb moisture; and an outer covering material covering the core material and the adsorbent. In the vacuum heat insulating material in which the inside of the outer covering material is decompressed and sealed, the outer covering material is composed of a surface protective layer, a gas barrier layer, and a heat fusion layer, and the outer covering material has two of the peripheral portion of the outer covering material. The heat fusion layer is fused with a thickness of 35 μm or more and 70 μm or less, and the adsorbent includes calcium oxide having a moisture absorption rate of 15 wt%/h or more and 32 wt%/h or less.

According to the vacuum heat insulating material of the present invention, by adopting the above configuration, increasing the film thickness of the heat fusion layer can sufficiently suppress the breakage of the core material caused by the pinhole, and the adsorbent can be quickly adsorbed from the heat fusion layer. Intrusive water vapor. Thereby, the degree of vacuum inside the vacuum heat insulating material can be maintained to suppress the thermal conductivity. Since it rises, the heat insulation property of a vacuum heat insulation material can be maintained for a long time.

1‧‧‧Vacuum insulation

2‧‧‧ core material

3‧‧‧Adsorbent

4‧‧‧Outsourcing materials

41‧‧‧Surface protection layer

42‧‧‧ gas barrier layer

43‧‧‧Hot fusion layer

43a‧‧‧Sealing Department

100‧‧‧heat insulation box

110‧‧‧ inner box

120‧‧‧Outer box

130‧‧‧Polyurethane foam insulation

T‧‧‧The thickness of the seal

Fig. 1 is a cross-sectional view showing a schematic structure of a vacuum heat insulating material of the first embodiment.

Fig. 2 is a scatter diagram showing the relationship between the amount of increase in thermal conductivity of the vacuum heat insulating material of Fig. 1 and the moisture absorption rate.

Fig. 3 is a scatter diagram showing the relationship between the relative spur strength of the vacuum heat insulating material of Fig. 1 and the film thickness of the heat fusion layer.

Fig. 4 is a scatter diagram showing the relationship between the number of broken pockets caused by the pinholes of the vacuum heat insulating material of Fig. 1 and the film thickness of the heat fusion layer.

Fig. 5 is a scatter diagram showing the relationship between the amount of increase in thermal conductivity of the vacuum heat insulating material of Fig. 1 and the film thickness of the heat fusion layer.

Fig. 6 is a cross-sectional view showing a schematic structure of a heat insulating box of the second embodiment.

Implementation type 1

A vacuum heat insulating material according to Embodiment 1 of the present invention will now be described. Fig. 1 is a cross-sectional view showing a schematic structure of a vacuum heat insulating material 1 of the first embodiment. In the following drawings including Fig. 1, the relationship or shape of the dimensions of the respective constituent members may be different from the actual ones. The specific dimensions of each component should be judged after considering the following description.

As shown in Fig. 1, the vacuum heat insulating material 1 is a heat insulating material that achieves low thermal conductivity by internal vacuum, and includes a core material 2 that holds a vacuum space, an adsorbent 3 that absorbs at least moisture, and a core material 2 that is covered. Outer material 4 with adsorbent 3. other than The vacuum space determined by the packaging material 4 is condensed by a hot melt film in a state where the opening portion is decompressed, and is pressure-reduced and sealed. The vacuum heat insulating material 1 as a whole has a substantially rectangular flat plate shape.

The surface of the vacuum heat insulating material 1 is given a shape of unevenness for the purpose of avoiding interference with a copper pipe for heat release. The uneven portion can be provided as necessary, and the difference between the surface of the concave portion and the surface of the convex portion, that is, the depth of the groove, is such that the diameter of the copper pipe is about 4 mm, and is less than or equal to 10 mm.

The core material 2 is used for the purpose of maintaining a vacuum space. As the core material 2, a fiber assembly such as glass wool is generally used. Further, the fiber assembly constituting the core material 2 may be formed by heat and pressure molding, or may be sealed with an inner packaging material, or may be a combination of a bonding agent.

The adsorbent 3 adsorbs water vapor inside the vacuum heat insulating material 1 and maintains the degree of vacuum, thereby suppressing an increase in thermal conductivity, and using calcium oxide (CaO) having a moisture absorption rate of 15 wt%/h or more and 32 wt%/h or less. . The moisture absorption rate is a value calculated from the weight increase rate when it is placed in an environment of a temperature of 25 ° C and a relative humidity of 90%.

The adsorbent 3 can be packaged in a permeable packaging material. The air-permeable packaging material can be formed of a gas permeable member selected from paper, nonwoven fabric, plastic film or mesh cloth, and workability can be expected. The packaging material may be formed by laminating two or more types of members selected from these air-permeable members.

The outer covering material 4 is composed of two laminated film sheets, and the laminated film sheet has a multilayer structure in which the surface protective layer 41, the gas barrier layer 42 and the heat fusion layer 43 are formed. The two heat fusion layers 43 are fused and joined at the sealing portion 43 to coat the core material 2 and the adsorbent 3. At this time, the outer covering material 4 is fused by the sealing portion 43a in a state where the pressure is reduced to a vacuum of about 1 to 3 Pa (Pascal), and the pressure-reducing sealing is performed.

The film thickness of the surface protective layer 41 is 25 μm or the like, and the material may be a thermoplastic resin having a high melting resistance at a melting point of 150° C. or higher. For example, a stretched polyamide such as stretched nylon, polyethylene terephthalate, stretched polypropylene or the like can be used. Stretched nylon can be abbreviated as ONY, polyethylene terephthalate can be abbreviated as PET, and stretched polypropylene can be abbreviated as OPP.

The gas barrier layer 42 is formed by using a thermoplastic resin or a metal film having excellent water vapor and air barrier properties as a material, and a single layer having a thickness of 24 μm or a layer having a thickness of 12 μm. The material of the gas barrier layer 42 may be aluminum vapor-deposited polyethylene terephthalate, aluminum vapor-deposited ethylene-vinyl alcohol, aluminum foil, or a combination thereof. Further, the inorganic material to be vapor-deposited on the thermoplastic resin is not limited to aluminum, and may be alumina, cerium oxide, or a combination thereof. Ethylene-vinyl alcohol can be abbreviated as EVOH.

The film thickness t of the heat fusion layer 43 may be 35 μm or more and 70 μm or less, and the film thickness T of the sealing portion 43a formed by fusion between the heat fusion layers 43 may be 70 μm or more and 140 μm or less. The material is selected from a thermoplastic resin having a melting point of 150 ° C or less, but is not specifically specified. The heat fusion layer 43 is, for example, a low density polyethylene or a linear low density polyethylene. High-density polyethylene with high elasticity and excellent water vapor barrier properties, or unstretched polypropylene is more preferable. 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, and unstretched polypropylene may be abbreviated as CPP. In addition, in the following description, the above abbreviation is described in parentheses.

Next, the moisture absorption rate of the adsorbent 3 will be described in detail with reference to Fig. 2 . Fig. 2 is a scatter diagram showing the relationship between the moisture absorption rate of the vacuum heat insulating material 1 of Fig. 1 and the amount of increase in thermal conductivity. In Fig. 2, the thermal fusion layer 43 uses a low linearity. In the case of density polyethylene (LLDPE), it is indicated by a black dot, and in the case of using a non-stretched polypropylene (CPP), it is represented by a black square. As shown in Fig. 2, when calcium oxide (CaO) is used as the adsorbent 3, if the moisture absorption rate of calcium oxide (CaO) is changed and the moisture absorption rate is in the range of 15 wt%/h or more, the thermal conductivity is maintained. A state in which the amount of increase is small. This is because when the moisture absorption rate is 15% by weight/h or more, the vacuum is maintained for a long period of time, and the increase in thermal conductivity is suppressed. On the other hand, when the moisture absorption rate is 15 wt%/h or less, and the vicinity of 15 wt%/h is used as a boundary, the amount of increase in thermal conductivity is greatly increased. This is because the moisture absorption rate of the adsorbent is insufficient, so that the water vapor is increased and the thermal conductivity is increased. When the material used for the heat fusion layer 43 is changed, the same tendency is exhibited without being affected by the material.

From the above description, it can be understood that calcium oxide (CaO) having a moisture absorption rate of 15% by weight/hour or more is used as the adsorbent 3, and the thermal conductivity of the vacuum heat insulating material 1 can be maintained for a long period of time. Further, the amount of water which can be theoretically adsorbed by calcium oxide (CaO) is 32% by weight, so 32% by weight/h is the upper limit of the moisture absorption rate which the adsorbent 3 can obtain. In addition, when the moisture absorption rate is 17 wt%/h or more, the amount of increase in thermal conductivity can be stably maintained, and when the moisture absorption rate is 22 wt%/h or less, moisture absorption and loss of activity in the production step can be suppressed. . Therefore, the moisture absorption rate of the adsorbent 3 is preferably set to be 17 wt% / h or more and 22 wt% / h or less.

In addition, the measurement of the moisture absorption rate can be performed by the following method. First, the weight of calcium oxide (CaO) was measured by an electronic balance as a sample. Then, the sample was allowed to stand in a constant temperature and humidity chamber at a temperature of 25 ° C and a relative humidity of 90% for one hour, and then the weight of the sample was measured immediately by an electronic balance. The moisture absorption rate was calculated from the change in weight before and after standing in the constant temperature and humidity chamber. When calcium oxide (CaO) is used, it can be heated in an electric furnace at a temperature of 1000 ° C for 4 hours. After that, the moisture absorption rate was calculated in the same manner.

Next, the heat fusion layer 43 will be described in detail with reference to FIGS. 3 to 5. Fig. 3 is a scatter diagram showing the relationship between the relative spur strength of the vacuum heat insulating material 1 of Fig. 1 and the film thickness t of the heat fusion layer 43. Fig. 4 is a scatter diagram showing the relationship between the number of broken pockets caused by the pinholes of the vacuum heat insulating material 1 of Fig. 1 and the film thickness t of the heat fusion layer 43. In addition, FIG. 5 is a scatter diagram showing the relationship between the amount of increase in thermal conductivity of the vacuum heat insulating material 1 of FIG. 1 and the film thickness t of the heat fusion layer 43. In the third to fifth figures, the case where the heat fusion layer 43 is made of linear low-density polyethylene (LLDPE) is indicated by a black dot, and when the non-stretched polypropylene (CPP) is used, it is represented by a black square. The relative spur strength refers to the relative spur strength when the strength of the linear low-density polyethylene (LLDPE) of 30 μm is punctured with a needle having a diameter of 0.4 mm. Further, in Fig. 4, the vacuum heat insulating material 1 having a film thickness t of 1000 sheets of the heat fusion layer 43 is produced, and the number of the vacuum heat insulating materials 1 in which pinholes are generated and the bag breakage occurs is regarded as pinhole generation. The number of broken bags caused.

When focusing on the film thickness t of the heat fusion layer 43, as shown in Fig. 3, the heat fusion layer 43 of any one of the materials is used. When the film thickness t of the heat fusion layer 43 is 35 μm or more, the relative spur strength will be It is increased by a factor of 2 when the film thickness t is 30 μm. Further, as shown in Fig. 4, when the film thickness t of the heat fusion layer 43 is 35 μm or more, the number of broken bags caused by pinholes is drastically reduced as compared with the case where the film thickness t is 30 μm. Then, when the film thickness t is 50 μm or more, the relative spur strength is maintained, and the number of broken bags caused by the occurrence of pinholes is stably maintained.

On the other hand, when focusing on the amount of increase in thermal conductivity, as shown in Fig. 5, the film thickness t of the heat fusion layer 43 is between 20 μm and 80 μm, and the amount of increase in thermal conductivity shows a gradual rise, but when the film Thick t reaches 80μm, it will be urgent Risingly. The film thickness t of the heat fusion layer 43 is 80 μm, and the amount of increase in thermal conductivity is twice the value when the film thickness t is 20 μm. When the film thickness t of the heat fusion layer 43 is in the range of 20 μm to 80 μm, since the adsorbent 3 can adsorb the invaded water vapor, the low thermal conductivity can be maintained. However, when the film thickness t of the heat fusion layer 43 is further increased, the intrusive water vapor increases as the film thickness T of the sealing portion 43a increases, because the moisture absorption rate of the adsorbent 3 decreases, so the internal vacuum degree Decreased with time, causing an increase in thermal conductivity.

As described above, the film thickness t of the heat fusion layer 43 is set to 35 μm or more and 70 μm or less, and the film thickness T of the sealing portion 43a obtained by fusing the two heat fusion layers 43 is determined to be 70 μm or more and 140 μm or less. . Further, the moisture absorption rate of the adsorbent 3 is determined to be 15 wt% / h or more and 32 wt% / h or less.

Next, the manufacturing steps of the vacuum heat insulating material of the first embodiment will be described. In the manufacturing process of the vacuum heat insulating material 1 of the first embodiment, the core material 2 is first covered with the outer covering material 4 composed of the multilayer protective structure of the surface protective layer 41, the gas barrier layer 42, and the heat fusion layer 43. At this time, the film thickness t of the heat fusion layer 43 is set to 35 μm or more and 70 μm or less. Then, the core material 2 and the outer covering material 4 are dried. The core material 2 covering the outer covering material 4 is subjected to a heat treatment at 100 ° C for 2 hours to remove moisture from the core material 2 and the outer covering material 4 .

Next, the adsorbent 3 is disposed between the core material 2 and the outer covering material 4, and the adsorbent 3 is set to be 15 wt%/h or more and 32 wt%/h or less. Then, the inside of the outer covering material 4 is depressurized to a degree of vacuum of about 1 to 3 Pa, and the opening portion is fused with a hot glue film or the like in this reduced pressure state, and the inside of the outer covering material 4 is pressure-reduced. At this time, the pressure-sealing of the outer covering material 4 causes the core material 2 to spur the heat fusion layer 43. However, since the film thickness t of the heat fusion layer 43 is set to 35 μm or more and 70 μm or less, it is possible to suppress the cause. A broken bag caused by pinholes.

The vacuum heat insulating material 1 obtained through the above steps is easily invaded by water vapor because of the thickness of the sealing portion 43a formed by the fusion of the two heat fusion layers 43, but the moisture absorption rate is 15 wt%/h or more and 32 wt%/h or less. Adsorbent 3 rapidly adsorbs invading water vapor. Therefore, the degree of vacuum inside the vacuum heat insulating material 1 can be maintained, and the amount of increase in thermal conductivity can be maintained for a long period of time. In particular, when the moisture absorption rate of the adsorbent 3 is 17 wt% / h or more and 22 wt% / h or less, the increase in the thermal conductivity is stably lowered, and the decrease in the moisture absorption ability in the middle of the production step is avoided.

In addition, the vacuum heat insulating material 1 may be subjected to press working in order to avoid interference with a copper pipe for heat radiation, and the vacuum heat insulating material 1 may be given a shape of unevenness. In this case, the difference in the unevenness formed by the press working is preferably 2 mm or more and 10 mm or less.

Further, the outer covering material 4 may have a thickness T of the sealing portion 43a formed by fusing the two heat fusion layers 43 having a thickness t of 35 μm or more and 70 μm or less, and the film thickness T of the outer layer 4 may be 70 μm or more and 140 μm or less. Further, two sheets of the outer covering material 4 covering the core material 2 and the adsorbent 3 may be used, and one sheet of the outer covering material 4 can be folded and used. When the core material 2 and the adsorbent 3 can be sealed under reduced pressure, the number of the outer covering members 4 is not limited.

Next, the vacuum heat insulating material 1 of the present embodiment 1 was produced, and compared with Examples 1 to 3 in Comparative Examples 1 to 3. The comparison results are explained below.

<Example 1>

In the first embodiment, the relationship between the number of broken bags caused by pinhole generation and the film thickness t of the heat fusion layer 43 was examined. Vacuum insulation material 1 is made of glass wool 2. The outer covering material 4 is a surface protective layer 41 made of stretched nylon (ONY) having a film thickness of 25 μm, and is composed of polyethylene terephthalate (PET) having a film thickness of 12 μm and ethylene-vinyl alcohol (EVOH) having a film thickness of 12 μm. A gas barrier layer 42 is formed. Then, a laminated film in which the surface protective layer 41, the gas barrier layer 42, and the heat fusion layer 43 are laminated is used as the outer covering material 4. The core material 2 is covered with the outer covering material 4, and the vacuum heat insulating material 1 is produced. As a sample of Example 1, a vacuum heat insulating material 1 having a heat fusion layer 43 having a film thickness t of 35 μm and a heat fusion layer 43 having a film thickness t of 50 μm was used. The material of the heat fusion layer 43 is linear low density polyethylene (LLDPE) and a non-stretch polypropylene (CPP) having a higher modulus of elasticity. Then, 1000 samples each of which was formed by a combination of various film thicknesses and materials were prepared.

The sample used in Comparative Example 1 was a linear low-density polyethylene (LLDPE) having a film thickness of 30 μm as a heat fusion layer 43 of the outer cladding material 4 of the vacuum heat insulating material, and other structures were the same as those of the sample of Example 1. In the same manner as the sample of Example 1, 1000 samples were prepared for the sample of Comparative Example 1.

Table 1 shows the results of comparing the number of broken bags caused by pinholes in the samples of Example 1 and Comparative Example 1.

As shown in Table 1, in the case where the film thickness t of the heat-fusible layer 43 of the linear low-density polyethylene (LLDPE) in Comparative Example 1 was 30 μm, the number of broken bags caused by pinholes was 42, and the frequency of occurrence was 4.2. %.

In contrast, in the sample of Example 1, linear low density polyethylene When the film thickness t of the heat fusion layer 43 of (LLDPE) was 35 μm, the number of broken packets caused by pinholes was 19, and the frequency of occurrence was 1.9%. That is, in the sample of Example 1, the frequency of pinhole generation was reduced by 2.3% compared with Comparative Example 1. Further, when the film thickness t of the heat fusion layer 43 was 50 μm, the number of broken bags was reduced to 14 pieces due to pinholes, but only 5 pieces were reduced as compared with the case where the film thickness t was 35 μm.

From the above, when the film thickness t of the heat fusion layer 43 is increased from 30 μm to 35 μm, the number of broken pockets is greatly reduced by pinhole generation, but when the film thickness t is increased from 35 μm to 50 μm, pinholes are generated to cause breakage of the bag. The number of counterfeits has not changed much.

Further, in the sample of Example 1 using the unstretched polypropylene (CPP) having a film thickness t of 35 μm of the heat fusion layer 43, pinhole generation resulted in a reduction in the number of broken bags to seven. The heat fusion layer 43 is formed of a material having a higher modulus of elasticity, and the generation of pinholes can be further suppressed. Further, in the case where the film thickness t is 50 μm, the number of broken bags is five, and the number of broken bags is reduced by two, which is less than two when the film thickness t is 35 μm. Even when unstretched polypropylene (CPP) is used as the material of the heat fusion layer 43, the film thickness t is 35 μm and the film thickness t is 50 μm, and the number of broken pockets is not so large due to pinhole generation. The change.

<Example 2>

In the second embodiment, the relationship between the increase in the thermal conductivity of the vacuum heat insulating material 1 and the moisture absorption rate of the adsorbent 3 was examined. The sample used in Example 2 was the same as Example 1 except for the portions described below. The moisture absorption rate is a value calculated from the weight increase rate when it is placed in an environment where the temperature is 25° C. and the relative humidity is 90%. Moreover, the rate of increase in thermal conductivity is the thermal conductivity and temperature in the survey after manufacture. The thermal conductivity of 30 days was stored in an environment of 25° C. and a relative humidity of 60%, and the difference between the two was calculated as an increase amount.

After the vacuum heat insulating material 1 of the second embodiment and the vacuum heat insulating material of the comparative example 2 were manufactured, the thermal conductivity values of any of the samples were both 1.8 mW/(m.K), and the moisture absorption of the adsorbent 3 was not observed. The difference in thermal conductivity caused by speed.

In the second embodiment, as a sample, a vacuum heat insulating material 1 in which the core material 2 and the adsorbent 3 were coated with the outer covering material 4 was produced. The moisture absorption rate of the adsorbent 3 was 15 wt% / h, 18 wt% / h, and 32 wt% / h. Further, as in the case of Example 1, the materials of the heat fusion layer 43 of various samples were made of linear low density polyethylene (LLDPE) and unstretched polypropylene (CPP). Further, since the film thickness t of the heat fusion layer 43 is a fixed value of 50 μm, the film thickness T of the sealing portion 43a is 100 μm.

In Comparative Example 2, the moisture absorption rate of the adsorbent 3 was 14 wt%/h of calcium oxide, and the other compositions were the same as those of the vacuum heat insulating material 1 of Comparative Example 1. Further, in Comparative Example 2, similarly to the second embodiment, the film thickness t of the heat fusion layer 43 was a fixed value of 50 μm, and the film thickness T of the sealing portion 43a was 100 μm.

Table 2 shows the results of comparing the amounts of increase in thermal conductivity of the vacuum heat insulating material 1 of the samples of Example 2 and Comparative Example 2.

As shown in Table 2, in the vacuum heat insulating material of Comparative Example 2, the amount of increase in thermal conductivity was 0.4 mW/(m.K). On the other hand, in the vacuum heat insulating material 1 of Example 2, heat transfer was performed under all the adsorbents 3 having a moisture absorption rate of 15 wt%/h or more. The increase in the rate is 0.2 mW/(m.K). When the heat fusion layer 43 is a sample of a non-stretched polypropylene (CPP), the amount of increase in thermal conductivity is lower, which is 0.1 mW/(m.K).

As described above, the moisture absorption rate of the adsorbent 3 is made 15% by weight/h or more, whereby the amount of increase in thermal conductivity is maintained at a low value for a long period of time. Further, by using the unstretched polypropylene (CPP) as the heat fusion layer 43, a lower amount of change in thermal conductivity can be obtained.

<Example 3>

In the third embodiment, the relationship between the number of broken bags and the moisture absorption rate caused by the occurrence of pinholes in the vacuum heat insulating material 1 was examined. The samples used in Example 3 and Comparative Example 3 were the same as in Example 1 except for the portions described below.

The film thickness t of the heat fusion layer 43 of Example 3 was 50 μm. In the comparative example 3, the film thickness t of the heat fusion layer 43 is set to 30 μm which is equal to or less than the lower limit of the heat fusion layer 43 and 80 μm which is equal to or higher than the upper limit of the heat fusion layer 43. Any of the samples used linear low density polyethylene (LLDPE) as the material of the heat fusion layer 43, and the adsorption rate of the adsorbent 3 was a fixed value of 18 wt%/h.

Table 3 shows the results of comparing the number of broken bags caused by pinholes in the samples of Examples 3 and 3 and the amount of increase in thermal conductivity during vacuum heat insulation.

as shown in Table 3. In Comparative Example 3, the number of broken bags caused by pinholes was caused in a sample of 30 μm in which the film thickness t of the heat fusion layer 43 was equal to or less than the lower limit value. It is 42. Further, the increase in the thermal conductivity was 0.2 mW/(m.K), and the number of broken bags caused by pinholes could not be suppressed.

In the sample of 80 μm in which the film thickness t of the heat fusion layer 43 was equal to or higher than the upper limit value, the number of broken bags caused by pinhole generation was 15. Further, the increase in the thermal conductivity was 0.3 mW/(m.K), and the increase in the thermal conductivity could not be suppressed.

On the other hand, in the third embodiment, the number of broken bags caused by pinhole generation was 14, and the amount of change in thermal conductivity was 0.2 mW/(m.K), and the number of broken bags and the thermal conductivity caused by pinholes were caused. The increase is suppressed.

As described above, the film thickness t of the heat fusion layer 43 is set to 35 μm or more and 70 μm or less, and the moisture absorption rate of the adsorbent 3 is set to 15 wt%/h or more and 32 wt%/h or less, whereby pinhole generation can be suppressed. The vacuum insulation material 1 which adsorbs the water vapor which invaded into the inside, and the number of the number of broken bags.

In the vacuum heat insulating material 1 of the first embodiment described above, the film thickness t of the heat fusion layer 43 is set to 35 μm or more and 70 μm or less. Therefore, having a sufficient thickness can sufficiently suppress the breakage of the pinhole caused by the pinhole of the core material 2. Further, since the moisture absorption rate of the adsorbent 3 is set to 15 wt%/h or more and 32 wt%/h or less, the two heat fusion layers 43 are fused, and have a sufficient moisture absorption rate to sufficiently adsorb the film thickness T from 70 μm to 140 μm. The water vapor invaded by the sealing portion 43a. Thereby, the degree of vacuum in the vacuum space can be maintained, the increase in thermal conductivity can be suppressed, and the heat insulating properties can be maintained for a long period of time.

In particular, by setting the moisture absorption rate to be 17 wt%/h or more and 22 wt%/h or less, the increase in the thermoelasticity can be stably lowered, and the decrease in the moisture absorption ability in the production step can be suppressed.

Moreover, by having a high modulus of elasticity and excellent water vapor barrier properties Density polyethylene or non-stretched polypropylene forms a heat fusion layer, and it is possible to further suppress the occurrence of pinholes caused by pinholes in the spur of the core material 2, and to reduce the amount of intrusion of water vapor.

In addition, by providing the uneven portion having a difference between the surface of the concave portion and the surface of the convex portion of 2 mm or more and 10 mm or less on the surface of the vacuum heat insulating material 1, the heat between the vacuum heat insulating material 1 and the copper pipe for heat dissipation can be promoted. exchange.

Moreover, when the adsorbent 3 is coated with a packaging material formed by any of a paper, a nonwoven fabric, a plastic film, or a mesh cloth, the air permeability of the adsorbent 3 can be ensured and the workability can be improved. The packaging material may be formed by a plurality of laminated layers formed of paper, non-woven fabric, plastic film, or mesh cloth.

The core material 2 may be a fiber assembly having low thermal conductivity and easy handling, especially glass wool.

Implementation type 2

Fig. 6 is a cross-sectional view showing a schematic structure of the heat insulating box 100 of the second embodiment. The heat insulation box 100 needs to have a long-term heat insulation performance such as a refrigerator or the like.

As shown in FIG. 6, the heat insulation box 100 has an inner box 110 and an outer box 120. Then, the space between the inner box 110 and the outer box 120 is placed with the vacuum heat insulating material 1 described in the first embodiment, and the inner box 110 and the outer box 120 are insulated from each other. The position at which the vacuum heat insulating material 1 is disposed is disposed, for example, at a position 3 where the outer wall surface of the inner box 110 is bonded to the outer wall surface, and the inner box 110 and the outer box 120 can be insulated from each other.

As described above, the heat insulating box 100 is provided with the vacuum heat insulating material 1 having a low thermal conductivity. Thereby, the thermal conductivity between the inner box 110 and the outer box 120 is maintained at a low level, so that the heat insulating performance of the heat insulating box 100 can be maintained at a high level for a long period of time. A device such as a refrigerator having the heat insulating box 100 can reduce power consumption.

The vacuum heat insulating material 1 has higher heat insulating properties than the polyurethane foam heat insulating material 130 and the like, and therefore the heat insulating box 100 has higher heat insulating properties than the heat insulating box 100 using only the polyurethane foam heat insulating material 130. However, the portion other than the vacuum heat insulating material 1 in the space between the inner box 110 and the outer box 120 may be filled with the urethane foam heat insulating material 130.

Moreover, in the above description, the vacuum heat insulating material 1 of the heat insulation box is bonded to the outer wall surface of the inner case 110, but the vacuum heat insulating material 1 may be bonded to the inner wall surface of the outer case 120. The vacuum heat insulating material 1 may not be bonded to any of the inner case 110 and the outer case 120 in the space between the inner case 110 and the outer case 120 by using a spacer or the like. In the above description, the same portions as those of the heat insulating box used in a general refrigerator or the like are omitted from illustration and description.

The vacuum heat insulating material 1 of the present invention is not limited to the above-described embodiment, and various modifications can be made. The above-described respective embodiments and modifications can be implemented in combination with each other.

For example, although the drying of the core material 2 and the outer covering material 4 is performed by heat treatment at 100 ° C for 2 hours in the manufacturing step, the temperature and time of the heat treatment are sufficient to remove the moisture of the core material 2 and the outer covering material 4 . And time, there is no limit. Moreover, the drying of the core material 2 and the outer covering material 4 is performed in a state in which the outer covering material 4 is coated with the core material 2, but the core material 2 and the outer covering material 4 may be separately dried, and then the outer covering material 4 may be used to coat the core. Material 2.

Further, in the manufacturing process of the vacuum heat insulating material 1 of the first embodiment, after the core material 2 and the outer covering material 4 are dried, the adsorbing material 3 is disposed between the core material 2 and the outer covering material 4, but the core may be The adsorbent 3 is disposed before the material 2 and the outer covering 4 are dried.

Further, in the above-described embodiment 2, the vacuum heat insulating material 1 is used for An example of the heat insulating box 100 of a refrigerator having a cold heat source is not limited thereto. The vacuum heat insulating material 1 can be used for a heat insulating box including a warm source, or a heat insulating box including a cold heat source and a warm heat source, for example, a refrigerator. In addition, the vacuum heat insulating material 1 is not only used as a heat insulating member of the heat insulating box 100, but may be used as a heat insulating device such as an air conditioner, a vehicle air conditioner, or a water heater, or a heat insulating member of a warming machine. It is not a predetermined shape, and it can also be used for a heat insulation bag or a heat insulation container which has a deformable outer bag and inner bag.

1‧‧‧Vacuum insulation

2‧‧‧ core material

3‧‧‧Adsorbent

4‧‧‧Outsourcing materials

41‧‧‧Surface protection layer

42‧‧‧ gas barrier layer

43‧‧‧Hot fusion layer

43a‧‧‧Sealing Department

T‧‧‧The thickness of the seal

Claims (8)

A vacuum heat insulating material comprising: a core material to maintain a vacuum space; an adsorbent to adsorb moisture; an outer covering material covering the core material and the adsorbent, wherein the inside of the outer covering material is sealed under reduced pressure, the outer packaging The material is composed of a surface protective layer, a gas barrier layer, and a heat fusion layer, and the outer covering material has a sealing portion formed by fusing two heat fusion layers of the peripheral portion of the outer covering material, and the thickness of the heat fusion layer is 35 μm or more. Below 70 μ, the adsorbent includes calcium oxide having a moisture absorption rate of 15 wt%/h or more and 32 wt%/h or less. The vacuum heat insulating material according to claim 1, wherein the adsorbent has a moisture absorption rate of 17 wt% / h or more and 22 wt% / h or less. The vacuum insulation material according to claim 1 or 2, wherein the heat fusion layer is high density polyethylene or non-stretch polypropylene. The vacuum heat insulating material according to claim 1 or 2, wherein the surface has an uneven portion of 2 mm or more and 10 mm or less. The vacuum heat insulating material according to claim 1 or 2, wherein the packaging material of the adsorbent is a member selected from the first group consisting of paper, non-woven fabric, plastic film, and mesh cloth. Alternatively, it is a member in which two or more types of members selected from the first group are laminated. The vacuum heat insulating material according to claim 1 or 2, wherein the core material is a fiber aggregate. The vacuum insulation material according to claim 1 or 2, wherein the core material is glass wool. A heat insulation box comprising: the vacuum insulation material according to claim 1 or 2.