Vacuum heat insulation material

Abstract

The invention provides a vacuum heat insulation material which can suppress the inflow of gas maintained before vacuum, and can exert high heat insulation performance. The laminated film comprises a core material (10) and a coating material (20) formed by sealing the peripheral edge part of one or a plurality of laminated films, the coating material (20) is provided with a heat welding layer (21) arranged on the core material (10) side and a base material layer (22) arranged on the outer side of the heat welding layer (21), and more than one thin film barrier layer (24) is arranged between the heat welding layer (21) and the base material layer (22).

Description

Technical Field

[0001] The present invention relates to a vacuum thermal insulation material. Background Art

[0002] Patent document 1 discloses a vacuum insulation material, which includes: a core material composed of an inorganic fiber aggregate; an outer packaging material having a surface protection layer, a gas barrier layer and a heat-sealing layer; and an adsorbent for absorbing moisture and gas components of the core material and the outer packaging material, wherein the gas barrier layer of the outer packaging material is stacked in a manner such that the metal surfaces of at least two metal layers are facing each other.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-263335 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] The present invention provides a vacuum heat insulating material which can suppress the gas retained by a base material layer before vacuumization from flowing into the interior of the vacuum heat insulating material and exhibit high heat insulating performance.

[0008] Technical solutions for solving technical problems

[0009] The vacuum insulation material of the present invention comprises a core material and a covering material 20 formed by sealing the peripheral portion of a single or multiple laminated films, and the vacuum insulation material is vacuum sealed, and the covering material comprises a heat-melting layer (also called a "heat-melting layer") arranged on the side of the core material and a substrate layer arranged on the outside of the heat-melting layer, and comprises one or more thin film barrier layers (also called "thin film barrier layers") between the heat-melting layer and the substrate layer.

[0010] In addition, this specification includes all the contents of Japanese Patent Application No. 2022-055059 filed in Japan on March 30, 2022.

[0011] Effects of the Invention

[0012] The vacuum insulation material of the present invention has a thin film barrier layer formed between the heat-sealing layer and the base material layer, so that the gas retained in the base material layer cannot pass through the thin film barrier layer, and can be suppressed from moving toward the heat-sealing layer. Therefore, the increase in the internal pressure of the vacuum insulation material caused by the gas can be suppressed, and the reduction in the insulation performance of the vacuum insulation material can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic cross-sectional view showing the vacuum heat insulating material according to the first embodiment.

[0014] Figure 2 This is a schematic cross-sectional view showing the cladding material according to the first embodiment.

[0015] Figure 3 It is an explanatory diagram showing the gas movement state in Embodiment 1. DETAILED DESCRIPTION

[0016] (Foundation, etc. that forms the basis of the present invention)

[0017] When the inventors conceived of the present invention, the following technology existed: a covering material of a vacuum insulation material has a barrier layer composed of a base material layer and a thin film barrier layer, and in order to improve gas barrier properties (barrier properties), two thin film barrier layers composed of metal are arranged in a facing manner.

[0018] However, the inventors found that when the substrate layer is arranged closer to the core material than the film barrier layer and a material with a high gas permeability is used, there is a technical problem that the substrate layer quickly retains gases such as oxygen and nitrogen in the outside air during storage before vacuum sealing, and after vacuum sealing, the gas retained by the substrate layer is gradually discharged to the inside of the vacuum insulation material, the internal pressure of the vacuum insulation material increases, and the thermal conductivity decreases. The subject of the present invention is to solve this technical problem.

[0019] Therefore, the present invention provides a vacuum heat insulating material capable of suppressing the gas retained by the base material layer before vacuumization from flowing into the interior of the vacuum heat insulating material and exhibiting high heat insulating performance.

[0020] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of already known matters are omitted, or where repeated descriptions of substantially the same structures are omitted.

[0021] In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present invention, and are not intended to limit the subject matter described in the claims.

[0022] (Implementation Method 1)

[0023] [1-1. Structure]

[0024] [1-1-1. Structure of vacuum insulation material]

[0025] Below, refer to Figures 1 to 3 Implementation method 1 will be described.

[0026] Figure 1 This is a schematic cross-sectional view showing an embodiment of a vacuum heat insulating material according to an embodiment.

[0027] like Figure 1As shown, the vacuum heat insulating material 1 includes a core material 10 , a gas adsorbent 11 , a moisture adsorbent 12 , and a covering material 20 covering the core material 10 and the gas adsorbent 11 .

[0028] The vacuum heat insulating material 1 is formed by covering a core material 10, a gas adsorbent 11, and a moisture adsorbent 12 with a covering material 20 and reducing the pressure inside.

[0029] The core material 10 can be made of a material that can resist atmospheric pressure and maintain thickness during decompression sealing, has a high porosity, and has low solid thermal conductivity, such as an inorganic powder assembly (especially silica powder) or an inorganic fiber assembly (especially glass fiber assembly).

[0030] The gas adsorbent 11 can be, for example, a chemical adsorbent such as calcium oxide, magnesium oxide, a physical adsorbent such as zeolite, or a mixture thereof, or a gas adsorbent alloy such as BaLi4. In addition, a copper ion exchange ZSM-5 type zeolite having a high gas adsorption capacity and adsorption ability can also be used. In addition, depending on the purpose of the vacuum insulation material 1, the gas adsorbent 11 can be omitted, or it can be sealed in the coating material 20 together with the moisture absorbent.

[0031] The material of the moisture adsorbent 12 is preferably a material having a large binding energy with the moisture to be adsorbed once and a large adsorption amount per unit weight, for example, calcium oxide, potassium oxide, etc. can be used.

[0032] [1-1-2. Structure of the covering material]

[0033] Next, the structure of the cladding material 20 will be described.

[0034] Figure 2 This is a schematic cross-sectional view of the cladding material according to the first embodiment.

[0035] like Figure 2 As shown, the covering material 20 has excellent gas barrier properties, and even if the vacuum heat insulating material 1 is stored in the atmosphere, little air enters the interior.

[0036] The cladding material 20 includes a heat-sealing layer 21 located on the core material 10 side and a base material layer 22 located outside the heat-sealing layer 21. The base material layer 22 may include an arbitrary layer such as a protective layer 23 outside.

[0037] The heat-sealing layer 21 is made of, for example, polyethylene or polypropylene.

[0038] The base material layer 22 is made of, for example, polyethylene terephthalate, nylon, polypropylene, or polyethylene.

[0039] Any layer may be provided as the protective layer 23, the second or third substrate layer, or a film barrier layer, etc. The protective layer 23 is preferably made of a material having high puncture strength, impact resistance, and scratch resistance, such as nylon.

[0040] In the present embodiment, a thin film barrier layer 24 is formed between the heat-sealing layer 21 and the base material layer 22 .

[0041] The thin film barrier layer 24 is formed of a vapor-deposited layer of a metal material such as aluminum. In this case, since the metal material can improve the barrier property, after the vacuum heat insulating material 1 is vacuum-sealed, it is possible to suppress the diffusion of gases such as nitrogen and oxygen toward the core material 10 .

[0042] In addition, the thin film barrier layer 24 may be composed of a vapor-deposited layer of a ceramic material such as a silicon dioxide material or an aluminum oxide material. In this case, when the thin film barrier layer 24 is a vapor-deposited layer of a metal material, heat conduction due to the thin film barrier layer 24 occurs, but by using a vapor-deposited layer of a ceramic material, the so-called heat bridge caused by heat conduction can be suppressed.

[0043] Whether the thin film barrier layer 24 is composed of a vapor-deposited layer of a metal material or a vapor-deposited layer of a ceramic material is selected according to the purpose of use of the vacuum heat insulating material 1 .

[0044] The thin film barrier layer 24 is formed by coating on any one of the heat seal layer 21 and the base layer 22. An adhesive layer may be provided between the thin film barrier layer 24 and the heat seal layer 21 or between the thin film barrier layer 24 and the base layer 22.

[0045] Furthermore, the thin film barrier layer 24 may be formed of two or more layers, and may also include a resin coating layer.

[0046] As a specific example of the structure of the coating material 20, for example, the coating material 20 is constructed as follows: polyethylene as a heat-melting layer 21, an adhesive layer, an aluminum vapor-deposited layer as a film barrier layer 24, and polyethylene terephthalate as a base layer 22 are stacked in sequence, and then an adhesive layer / aluminum vapor-deposited layer / polyethylene terephthalate / adhesive layer / nylon as a protective layer 23 are stacked in sequence on the outer layer.

[0047] As another example, the coating material 20 is constructed as follows: polyethylene as a heat-sealing layer 21, an adhesive layer, a polyvinyl alcohol coating / aluminum vapor-deposited layer as a film barrier layer 24, and polyethylene terephthalate as a base material layer 22 are stacked in sequence, and then an adhesive layer / polyvinyl alcohol layer / aluminum vapor-deposited layer / polyethylene terephthalate are stacked in sequence on the outer layer.

[0048] In addition, as another example, the coating material 20 is constructed in the following manner: polyethylene as a heat-melting layer 21, an adhesive layer, an alumina-silica composite vapor-deposited layer as a thin film barrier layer 24, and polyethylene terephthalate as a base layer 22 are stacked in sequence, and then an adhesive layer / alumina-silica composite vapor-deposited layer and polyethylene terephthalate as a protective layer 23 are stacked in sequence on the outer layer.

[0049] In addition, as another example, the coating material 20 is constructed in the following manner: polypropylene as a heat-melting layer 21, an aluminum vapor-deposited layer / adhesive layer / aluminum vapor-deposited layer as a film barrier layer 24, and polyethylene terephthalate as a base material layer 22 are stacked in sequence, and then an adhesive layer / aluminum vapor-deposited layer / polyethylene terephthalate are stacked in sequence on the outer layer.

[0050] In this way, the covering material 20 can be composed of various materials, and the thin film barrier layer 24 can also be composed of multiple layers.

[0051] The covering material 20 may be formed by sealing both side edges and end edges of a single film constituting the covering material 20 in a folded state.

[0052] As another example, the covering material 20 may be formed by bonding a plurality of films constituting the covering material 20 to each other and sealing four sides thereof.

[0053] [1-2. Function]

[0054] Next, the operation of this embodiment will be described.

[0055] Figure 3 : is an explanatory diagram showing the movement state of gas in Embodiment 1. Figure 3 The circles in the figure represent gas molecules.

[0056] First, the covering material 20 in which the thin film barrier layer 24 is provided between the heat-sealed layer 21 and the base material layer 22 is prepared.

[0057] In this state, the covering material 20 is formed into a bag shape, and the core material 10 is covered with the covering material 20 .

[0058] like Figure 3 As shown, since the cladding material 20 is exposed to the outside air, gas enters from the protective layer 23 side, the core material 10 side, or the side surface.

[0059] The amount of this gas increases with the passage of time, and the gas is retained in the heat-sealed layer 21 and the base material layer 22 .

[0060] Afterwards, if the inside of the covering material 20 is evacuated, Figure 3As shown, the gas retained in the heat-sealed layer 21 is gradually released from the core material 10 side. On the other hand, the gas retained in the base material layer 22 is released to the outside from the protective layer 23 side or the side surface.

[0061] At this time, since the thin film barrier layer 24 is formed between the heat seal layer 21 and the base layer 22 , the gas retained by the base layer 22 cannot pass through the thin film barrier layer 24 and does not move to the heat seal layer 21 side.

[0062] Furthermore, the vacuum heat insulating material 1 can be formed by sealing the covering material 20 during the vacuuming of the inside of the covering material 20. At this time, the gas retained by the heat-sealed layer 21 is mostly released from the core material 10 during the vacuuming process. On the other hand, the gas retained by the base material layer 22 is difficult to be discharged by vacuum exhaust and remains in the base material layer 22.

[0063] At this time, the thin film barrier layer 24 prevents the gas retained by the base material layer 22 from moving to the heat sealing layer 21, thereby suppressing the increase in the internal pressure of the vacuum heat insulating material 1 caused by the gas. As a result, the reduction in the heat insulating performance of the vacuum heat insulating material 1 can be suppressed.

[0064] Here, the relationship among the gas permeability P, solubility coefficient S, and diffusion coefficient D is expressed by the following equation.

[0065] P=S×D

[0066] The difference in solubility coefficient S among polymers is small, and the contribution of diffusion coefficient D is large.

[0067] If the diffusion coefficient D of the base material layer 22 is large, gas molecules such as nitrogen and oxygen are easily diffused and retained through the heat-sealing layer 21, and the gas molecules are retained for a long time from the time of film manufacturing. However, the gas molecules contained in the base material layer 22 are not completely degassed in the short vacuum exhaust time. Therefore, it can be seen that: when the thin film barrier layer 24 is not provided between the base material layer 22 and the heat-sealing layer 21, the gas slowly diffuses to the core material 10 side after the vacuum sealing of the vacuum insulation material 1, causing the internal pressure to rise.

[0068] When the base layer 22 is formed of the commonly used ethylene-vinyl alcohol copolymer, the diffusion coefficient D of the ethylene-vinyl alcohol copolymer is small and the amount of gas retained in the base layer 22 is small. Therefore, there is almost no problem even if the thin film barrier layer 24 is not provided between the base layer 22 and the heat-sealed layer 21.

[0069] However, as in the present embodiment, when the substrate layer 22 is formed of a material having a large diffusion coefficient D, that is, a gas permeability P, such as polyethylene terephthalate, nylon, polypropylene, and polyethylene, the amount of gas retained in the substrate layer 22 increases, and if the thin film barrier layer 24 is not provided, the gas is gradually released to the core material 10 side, causing an increase in the internal pressure.

[0070] In this embodiment, when a material having a high gas permeability P is used as the base layer 22, it is particularly effective when the nitrogen permeability between the base layer 22 and the heat-sealed layer 21 is within 1000 times under a dry condition of 20°C.

[0071] [1-3. Effects, etc.]

[0072] As described above, in this embodiment, there is a core material 10 and a covering material 20 formed by sealing the peripheral portion of a single or multiple laminate films (laminate films, composite films), the covering material 20 includes a heat-sealing layer 21 arranged on the side of the core material 10 and a base material layer 22 arranged on the outside of the heat-sealing layer 21, and includes one or more thin film barrier layers 24 between the heat-sealing layer 21 and the base material layer 22.

[0073] Thus, since the thin film barrier layer 24 is formed between the heat-sealing layer 21 and the base material layer 22, the gas retained by the base material layer 22 cannot pass through the thin film barrier layer 24, and can be suppressed from moving toward the heat-sealing layer 21. Therefore, the increase in the internal pressure of the vacuum heat insulating material 1 caused by the gas can be suppressed, and the reduction in the heat insulating performance of the vacuum heat insulating material 1 can be suppressed.

[0074] In the present embodiment, the base material layer 22 is made of polyethylene terephthalate, nylon, polypropylene, or polyethylene, and the heat-sealing layer 21 is made of polyethylene or polypropylene.

[0075] Thus, when the base material layer 22 is formed of a material having a high gas permeability, the thin film barrier layer 24 can suppress the release of gas from the base material layer 22 to the core material 10 side of the vacuum insulation material 1. Therefore, the increase in the internal pressure of the vacuum insulation material 1 caused by the gas can be suppressed, and the reduction in the insulation performance of the vacuum insulation material 1 can be suppressed.

[0076] In addition, in the present embodiment, the thin film barrier layer 24 includes a vapor-deposited layer of a metal material.

[0077] Thus, the barrier property of the thin film barrier layer 24 can be improved by the metal material, and after the vacuum heat insulating material 1 is vacuum-sealed, diffusion of gases such as nitrogen and oxygen toward the core material 10 can be suppressed.

[0078] In addition, in the present embodiment, the thin film barrier layer 24 includes a vapor-deposited layer of a silicon dioxide material or an aluminum oxide material.

[0079] Thus, by forming the thin film barrier layer 24 with a ceramic material such as a silica material or an alumina material, a so-called heat bridge caused by heat conduction can be suppressed.

[0080] (Other embodiments)

[0081] As described above, Embodiment 1 has been described as an example of the technology described in this application. However, the technology of the present invention is not limited thereto, and can be applied to embodiments in which changes, substitutions, additions, omissions, etc. have been made.

[0082] Industrial Applicability

[0083] The present invention can suppress the increase in internal pressure of the vacuum insulation material due to the gas by suppressing the inflow of the gas retained before vacuuming, and can be suitably used as a vacuum insulation material capable of suppressing the reduction in the insulation performance of the vacuum insulation material.

[0084] Description of Reference Numerals

[0085] 1 vacuum insulation material; 10 core material

[0086] 11 Gas adsorbent; 12 Moisture adsorbent

[0087] 20: cladding material; 21: thermal welding layer

[0088] 22 base material layer; 23 protective layer

[0089] 24 film barrier layers.

Claims

1. A vacuum-sealed vacuum heat insulating material, comprising a core material and a covering material 20, wherein the covering material is formed by sealing the peripheral edge of a single or a plurality of laminated films, wherein the vacuum heat insulating material is characterized in that: The cladding material comprises: a heat-sealing layer disposed on the core material side; and a base material layer disposed on the outer side of the heat-sealing layer, One or more thin film barrier layers are included between the heat-sealing layer and the base material layer.

2. The vacuum heat insulating material according to claim 1, characterized in that: The base material layer is made of polyethylene terephthalate, nylon, polypropylene, and polyethylene, and the heat-sealing layer is made of polyethylene and polypropylene.

3. The vacuum heat insulating material according to claim 1 or 2, characterized in that: The thin film barrier layer comprises a vapor-deposited layer of a metal material.

4. The vacuum heat insulating material according to claim 1 or 2, characterized in that: The thin film barrier layer comprises a vapor-deposited layer of silicon dioxide material or aluminum oxide material.

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