JP2009036358A - Vacuum heat insulating material and refrigerator equipped with the same - Google Patents

Abstract

[PROBLEMS] To provide a vacuum heat insulating material that is lightweight, has good initial thermal conductivity, has little deterioration over time, and has excellent heat insulating performance.
A vacuum heat insulating material (20) includes a core material (21) made of an open-cell resin foam foamed with a foaming agent containing a gas in a supercritical state, and has a gas barrier property and accommodates the core material (21). A decompressed bag.
[Selection] Figure 2

Description

  The present invention relates to a vacuum heat insulating material and a refrigerator including the same, and is particularly suitable for a vacuum heat insulating material having a resin foam as a core material and a refrigerator including the same.

  The conventional vacuum heat insulating material is composed of a core material made of open-celled rigid urethane foam formed by foaming using a water foaming agent, and a bag body having gas barrier properties and containing the core material and depressurizing the inside. There is something. As a patent document relating to this, Japanese Patent Laid-Open No. 57-133870 (Patent Document 1) can be cited.

JP-A-57-133870

  However, in the conventional vacuum heat insulating material, since the cell diameter of the core material, which is an open cell hard polyurethane foam foam-molded using a water foaming agent, is increased, the thermal conductivity of the vacuum heat insulating material is increased. It turns out that there is a problem of end. In addition, the gas generated from the rigid polyurethane foam, which is a core material using a water blowing agent, has a problem that the vacuum degree of the vacuum heat insulating material is lowered and the thermal conductivity is greatly deteriorated with time. I understood. Furthermore, although hard polyurethane foam, which is a core material using a water blowing agent, is lighter than a core material such as a glass fiber aggregate, its weight is required when many are used or many are handled simultaneously. Therefore, further weight reduction is desired. In particular, refrigerators are desired to be lighter in terms of safety and handling, but recently, a number of vacuum insulation materials have been used to improve the insulation performance of refrigerators. The weight reduction of heat insulating materials has become an important issue.

  An object of the present invention is to provide a vacuum heat insulating material that is light in weight, has good initial thermal conductivity, has little deterioration over time, and has excellent heat insulating performance, and a refrigerator including the same.

  A first aspect of the present invention for achieving the above-described object includes a core material formed of an open-cell resin foam formed by foaming with a foaming agent containing a gas in a supercritical state, and having a gas barrier property and the core. And a bag body containing the material and decompressed inside.

  Further, the second aspect of the present invention adsorbs a core material made of an open-cell resin foam foamed with a foaming agent containing supercritical nitrogen gas or carbon dioxide gas, and a gas component generated by the core material. And a bag body containing the core material and the adsorbent and depressurized inside, the bag body containing the core material and the adsorbent and depressurizing the inside and sealed And an outer bag having a gas barrier property that suppresses gas permeation substitution between the inside and the outside while accommodating the inner bag and sealing the inside by reducing the pressure.

A more preferable specific configuration example in the first or second aspect of the present invention is as follows.
(1) The core material is made of an open cell polystyrene resin foam obtained by foam molding using nitrogen gas or carbon dioxide gas in a supercritical state as a foaming agent.
(2) The communication rate of the polystyrene resin foam is 99% or more.
(3) The resin foam is foam-molded with a mixed foaming agent of supercritical carbon dioxide or nitrogen gas and water.

  Moreover, the 3rd aspect of this invention arrange | positions many vacuum heat insulating materials in the outer-plate side or inner-plate side of the space formed by an outer plate and an inner plate, and is in said spaces other than the said vacuum insulating material. In a refrigerator filled with a foam insulation material, the vacuum insulation material adsorbs a core material made of an open-cell resin foam formed by a foaming agent containing a gas in a supercritical state, and moisture and gas components of the core material. An adsorbent that has a gas barrier property, and a bag body that contains the core material and the adsorbent and decompresses the inside.

  According to the present invention, it is possible to provide a vacuum heat insulating material that is lightweight, has good initial thermal conductivity, has little deterioration over time, and has excellent heat insulating performance, and a refrigerator including the same.

  Hereinafter, a vacuum heat insulating material and a refrigerator according to an embodiment of the present invention will be described with reference to the drawings.

  First, the refrigerator of this embodiment is demonstrated, referring FIG. FIG. 1 is a longitudinal sectional view of a refrigerator provided with a vacuum heat insulating material 20 according to an embodiment of the present invention.

  The refrigerator includes a box body 12 and a plurality of door bodies 13 that open and close the opening of the box body 12. In the box 12, a refrigerator compartment 14a, a vegetable compartment 14b, an ice making compartment 15a, a freezer compartment 15b and the like are partitioned. The box 12 includes an outer plate 12e, an inner plate 12f, and a heat insulating wall 12a.

  The heat insulation wall 12a is comprised from the vacuum heat insulating material 20 and the foam heat insulating material 12b. The vacuum heat insulating material 20 is disposed on the outer plate 12e side or the inner plate 12f side in a space formed by the outer plate 12e and the inner plate 12f. A large number of the vacuum heat insulating materials 20 are installed in the space. The foam heat insulating material 12b is formed by filling a space around these vacuum heat insulating materials 20 with a hard polyurethane foam having adhesive force or the like. The vacuum heat insulating material 20 is fixed and the heat insulating wall 12a is formed by the adhesive force of the foam heat insulating material 12b.

  The door body 13 includes an outer plate 13e, an inner plate 13f, and a heat insulating wall 13a. The heat insulation wall 13a is comprised from the vacuum heat insulating material 20 and the foam heat insulating material 13b. The vacuum heat insulating material 20 is disposed on the outer plate 13e side or the inner plate 13f side in the space formed by the outer plate 13e and the inner plate 13f. The foam heat insulating material 13b is formed by filling a space around the vacuum heat insulating material 20 with a hard polyurethane foam having adhesive force. The vacuum heat insulating material 20 is fixed and the heat insulating wall 13a is formed by the adhesive force of the foam heat insulating material 13b.

  Next, the vacuum heat insulating material 20 of this embodiment is demonstrated, referring FIG. FIG. 2 is a diagram showing the vacuum heat insulating material used in the refrigerator of FIG. 1 with emphasis.

  The vacuum heat insulating material 20 includes a core material 21 made of an open-cell resin foam foamed with a foaming agent containing nitrogen gas or carbon dioxide gas in a supercritical state, and an adsorbent 21 that adsorbs gas components generated by the core material 21. And a bag body 25 containing the core material 21 and the adsorbent 22 and decompressing the inside thereof.

  The core material 21 is formed by cutting an open-celled rigid polyurethane resin foam panel or polystyrene resin foam panel foam-molded with a foaming agent containing nitrogen gas or carbon dioxide gas in a supercritical state into a predetermined size. . Since the core material 21 is formed of an open-cell resin foam, gas can be circulated. The communication rate of the resin foam is desirably 99% or more. Since the core material 21 having a gas flow is used, the flow with the adsorbent 21 is good, and the adsorption rate of moisture and gas contained in the inner bag 23 is improved. Since the core material 21 made of a resin foam obtained by foam molding using a gas in a supercritical state as a foaming agent is used, a vacuum heat insulating material reduced in weight can be provided. In particular, since it is based on so-called supercritical foam molding in which a gas in a supercritical state is molded as a foaming agent, it is easy to change the expansion ratio and to promote weight reduction.

  The adsorbent 22 is for adsorbing moisture and gas components generated from the core material 21, and is composed of, for example, a molecular sieve 13X that is a synthetic zeolite. Since the adsorbent 22 is filled in the adsorbent storage portion 21 a provided in the core material 21, it can be prevented that the adsorbent 22 protrudes from the outer surface of the vacuum heat insulating material 20. In FIG. 2, a part of the adsorbent 22 is shown, but the adsorbent 22 is filled so as to be filled in the adsorbent storage portion 21a.

  The bag body 25 contains the core material 21 and the adsorbent 22 and seals the inner bag 23 by reducing the pressure inside, and stores the inner bag 23 and seals the pressure by reducing the pressure inside. An outer bag 24 having gas barrier properties to be suppressed is provided. In FIG. 2, it is shown that there are gaps between the core material 21 and the inner bag 23, and between the inner bag 23 and the outer bag 24, but the vacuum heat insulating material 20 is configured without these gaps. Has been.

  Further, in order to prevent the adsorbent 22 from coming out of the adsorbent storage portion 21a, after the adsorbent 22 is filled in the core material 22, the core material 21 is stored in the inner bag 23 and the inner bag 21 is removed. The core material 21 is compressed while taking care to narrow the insertion portion 21b of the adsorbent storage portion 21a. In other words, after the adsorbent 22 is filled from the open insertion portion 21b of the adsorbent storage portion 21a, the inner bag 23 storing the core material 21 is compressed while being deaerated so as to close the opening of the insertion portion 21b. ing. With such a configuration, it is possible to shorten the installation work time of the adsorbent 22 and provide a vacuum heat insulating material in which moisture and gas components from the outside hardly adhere to the core material 21.

  As the inner bag 23, a synthetic resin film having a gas barrier property and capable of being thermally welded, for example, a bag formed of a high density polyethylene resin, an ethylene-vinyl alcohol resin, or the like is used. The inner bag 23 is configured to suppress permeation and substitution between the foaming gas in the bubbles of the core material 21 and the air outside the vacuum heat insulating material 20, and to prevent moisture and gas components from entering from the outside. In other words, the supercritical foaming gas in the core material 21 tends to be replaced by gas permeation with air, and the thermal conductivity of the air is inferior to that of the foaming gas. The inner bag 23 is used so as not to cause deterioration. In addition, the core material 21 and the adsorbent 22 are easy to adsorb moisture and gas components contained in the atmosphere. In particular, the adsorbent 22 can adsorb moisture and gas components relatively quickly and strongly from the periphery. It is configured as follows. For this reason, it is necessary for the core material 21 and the adsorbent 22 not to adsorb external moisture and gas components during the assembly work required in the manufacturing process and during the storage period as work in progress. The core material 21 and the adsorbent 22 are covered with an inner bag 23 having a gas barrier property. The outer bag 24 covers the inner bag 23 and is made of a laminate film having gas barrier properties.

  Next, the manufacturing method of a core material is demonstrated, referring FIG. FIG. 3 is an explanatory view of a production method for foam-molding an open-cell resin foam using a foaming agent containing nitrogen gas or carbon dioxide gas in a supercritical state.

  Urethane resin raw materials are broadly divided into polyether polyols and isocyanates. Of the polyol 31 and the isocyanate 32 stored in separate containers, carbon dioxide gas and nitrogen gas in a supercritical state are completely dissolved in the polyol 31. The gas to be dissolved is supplied by creating a gas in a supercritical state by the supercritical gas generator 34. However, since the amount of the gas affects the final bubbles, any of Examples 1 to 4 can be used. The gas is dissolved under the same conditions.

  Thereafter, these two liquids are stirred by the mixing head 33, and the stirred urethane stock solution 4 is injected from the injection head 35 into the target mold 36. In the case of pouring into the mold 36, as shown in FIG. 3, after dropping downward according to gravity, it rises upward in the mold 36 while increasing the volume by foaming. At this time, the solubility of the gas rapidly decreases due to reaction, heat generation, reduced pressure, etc., and the dissolved gas becomes supersaturated and starts to be released, forming bubble nuclei. After that, the nucleus grows into bubbles. Since the reaction proceeds in the middle of the bubble growth in this way, it is possible to control the growth using this, and the bubble diameter can be controlled. Thereby, fine bubbles can be obtained. In this way, the urethane resin flows into the entire mold 36 and fills the mold 36 to form a foam insulation.

  The above-mentioned open cell refers to a state in which the bubbles in the foam are not completely surrounded by the wall, are connected to other bubbles or the outside. The calculation of the communication rate (open cell rate) is based on ASTM D2856.

  Next, the vacuum heat insulating materials of the conventional example and Examples 1 to 4 will be described with reference to Table 1 showing the results of comparing the initial thermal conductivity, the temporal change of the thermal conductivity, and the weight. Although the structure of the vacuum heat insulating material of Examples 1-4 is the same as what is shown in FIG. 2, a prior art example is a structure which is not provided with the inner bag.

［従来例］
水発泡剤を用いて成形した硬質ポリウレタンフォームを芯材とした真空断熱材について、作製時（初期）と１年経過後の熱伝導率を熱伝導率測定装置で測定したところ、初期熱伝導率が５．５ｍＷ／ｍ・Ｋ、１年後の熱伝導率が９．０ｍＷ／ｍ・Ｋとなり、初期熱伝導率が大きく、しかも劣化が大きい傾向があることが分かった。これは、水発泡を用いたこと、芯材である硬質ポリウレタンフォームの内部から発生するガスにより、真空断熱材内の真空度が低下するため熱伝導率が悪化しているためである。また、この従来例の真空断熱材の重量を測定した値を１００として、以降の実施例１〜４における真空断熱材の重量とを比較している。
［実施例１］
超臨界状態の二酸化炭素ガスを発泡剤として発泡成形した硬質ポリウレタン樹脂発泡体を連通化したものを芯材とし、内袋として高密度ポリエチレン樹脂を用いて成形した真空断熱材について、作製時（初期）と１年経過後の熱伝導率を熱伝導率測定装置で測定したところ、初期熱伝導率が３．２ｍＷ／ｍ・Ｋ、１年後の熱伝導率が５．３ｍＷ／ｍ・Ｋと何れについても従来例の数値より顕著に良好であった。また、この実施例１の真空断熱材の重量を測定したところ、従来例の真空断熱材の重量を１００としたとき、９０の比率となり、軽量化が確認できた。以上より、実施例１によれば、熱伝導率においても、重量においても従来例より良好な数値が得られており、軽量且つ断熱性能に優れた真空断熱材を提供できる。
［実施例２］
超臨界状態の二酸化炭素ガスを発泡剤として発泡成形した硬質ポリウレタン樹脂発泡体を連通化したものを芯材とし、内袋としてエチレン−ビニルアルコール共重合体樹脂を用いて成形した真空断熱材について、作製時（初期）と１年経過後の熱伝導率を熱伝導率測定装置で測定したところ、初期熱伝導率が３．２ｍＷ／ｍ・Ｋ、１年後の熱伝導率が５．１ｍＷ／ｍ・Ｋと何れについても従来例の数値より顕著に良好であった。また、この実施例２の真空断熱材の重量を測定したところ、従来例の真空断熱材の重量を１００としたとき、９０の比率となり、軽量化が確認できた。以上より、実施例２によれば、熱伝導率においても、重量においても従来例より良好な数値が得られており、軽量且つ断熱性能に優れた真空断熱材を提供できる。
［実施例３］
超臨界状態の窒素ガスを発泡剤として発泡成形したポリスチレン樹脂発泡体を連通化したものを芯材とし、内袋としてエチレン−ビニルアルコール共重合体樹脂を用いて成形した真空断熱材について、作製時（初期）と１年経過後の熱伝導率を熱伝導率測定装置で測定したところ、初期熱伝導率が３．０ｍＷ／ｍ・Ｋ、１年後の熱伝導率が５．１ｍＷ／ｍ・Ｋと何れについても従来例の数値より顕著に良好であった。また、この実施例３の真空断熱材の重量を測定したところ、従来例の真空断熱材の重量を１００としたとき、５０の比率であり、従来例より顕著に軽量化が確認できた。以上より、実施例３によれば、熱伝導率においても、重量においても従来例より大幅に良好な数値が得られており、軽量且つ断熱性能に優れた真空断熱材を提供できる。
［実施例４］
超臨界状態の二酸化炭素ガスを発泡剤として発泡成形したポリスチレン樹脂発泡体を連通化したものを芯材とし、内袋として高密度ポリエチレン樹脂を用いて成形した真空断熱材について、作製時（初期）と１年経過後の熱伝導率を熱伝導率測定装置で測定したところ、初期熱伝導率が３．０ｍＷ／ｍ・Ｋ、１年後の熱伝導率が５．３ｍＷ／ｍ・Ｋと何れについても従来例の数値より顕著に良好であった。またこの実施例４の真空断熱材の重量を測定したところ、従来例の真空断熱材の重量を１００としたとき、５０の比率となり顕著な軽量化が確認できた。以上より、実施例４によれば、熱伝導率においても、重量においても従来例より良好な数値が得られており、軽量且つ断熱性能に優れた真空断熱材を提供できる。

[Conventional example]
About the vacuum heat insulating material which used hard polyurethane foam molded with water foaming agent as the core material, the thermal conductivity at the time of preparation (initial stage) and after one year passed was measured with the thermal conductivity measuring device. Was 5.5 mW / m · K, and the thermal conductivity after one year was 9.0 mW / m · K, indicating that the initial thermal conductivity tends to be large and the deterioration tends to be large. This is because the use of water foaming, and the gas generated from the inside of the hard polyurethane foam as the core material reduces the degree of vacuum in the vacuum heat insulating material, thereby deteriorating the thermal conductivity. Moreover, the value which measured the weight of the vacuum heat insulating material of this prior art example is set to 100, and the weight of the vacuum heat insulating material in subsequent Examples 1-4 is compared.
[Example 1]
At the time of production (initial stage) of vacuum heat insulating material molded using high-density polyethylene resin as the inner bag, with a solid polyurethane resin foam foamed with supercritical carbon dioxide gas as foaming agent ) And the thermal conductivity after 1 year was measured with a thermal conductivity measuring device, the initial thermal conductivity was 3.2 mW / m · K, and the thermal conductivity after 1 year was 5.3 mW / m · K. In all cases, the values were significantly better than those of the conventional example. Moreover, when the weight of the vacuum heat insulating material of Example 1 was measured, when the weight of the vacuum heat insulating material of the conventional example was set to 100, the ratio was 90, and weight reduction was confirmed. As described above, according to Example 1, both the thermal conductivity and the weight are better than those of the conventional example, and a vacuum heat insulating material that is lightweight and has excellent heat insulating performance can be provided.
[Example 2]
About the vacuum heat insulating material formed by using a solid polyurethane resin foam foamed with supercritical carbon dioxide gas as a foaming agent and using an ethylene-vinyl alcohol copolymer resin as an inner bag, When the thermal conductivity at the time of production (initial) and after one year passed was measured with a thermal conductivity measuring device, the initial thermal conductivity was 3.2 mW / m · K, and the thermal conductivity after one year was 5.1 mW / Both m · K and the numerical values of the conventional examples were significantly better. Moreover, when the weight of the vacuum heat insulating material of this Example 2 was measured, when the weight of the vacuum heat insulating material of the conventional example was set to 100, it became a ratio of 90 and the weight reduction was confirmed. As described above, according to Example 2, the heat conductivity and weight are better than those of the conventional example, and a vacuum heat insulating material that is lightweight and has excellent heat insulating performance can be provided.
[Example 3]
Vacuum heat insulating material molded using polystyrene resin foam formed by foaming with supercritical nitrogen gas as a foaming agent and using ethylene-vinyl alcohol copolymer resin as the inner bag. (Initial) and the thermal conductivity after 1 year was measured with a thermal conductivity measuring device, the initial thermal conductivity was 3.0 mW / m · K, and the thermal conductivity after 1 year was 5.1 mW / m · Both K and the values of the conventional examples were significantly better. Moreover, when the weight of the vacuum heat insulating material of this Example 3 was measured, when the weight of the vacuum heat insulating material of the conventional example was set to 100, it was a ratio of 50, and it was confirmed that the weight was significantly reduced as compared with the conventional example. As described above, according to Example 3, the heat conductivity and the weight are significantly better than those of the conventional example, and a vacuum heat insulating material that is lightweight and excellent in heat insulating performance can be provided.
[Example 4]
At the time of production (initial stage), vacuum insulation material molded using a high-density polyethylene resin as the inner bag made of a continuous polystyrene resin foam foamed with supercritical carbon dioxide gas as a foaming agent The thermal conductivity after 1 year was measured with a thermal conductivity measuring device. The initial thermal conductivity was 3.0 mW / m · K, and the thermal conductivity after 1 year was 5.3 mW / m · K. Was also significantly better than the numerical value of the conventional example. Moreover, when the weight of the vacuum heat insulating material of this Example 4 was measured, when the weight of the vacuum heat insulating material of the conventional example was set to 100, it became a ratio of 50 and the remarkable weight reduction was confirmed. As mentioned above, according to Example 4, the numerical value better than the prior art example is obtained also in terms of thermal conductivity and weight, and a vacuum heat insulating material that is lightweight and excellent in heat insulating performance can be provided.

It is a longitudinal cross-sectional view of the refrigerator provided with the vacuum heat insulating material of one Embodiment of this invention. It is a figure which emphasizes and represents the vacuum heat insulating material used for the refrigerator of FIG. It is explanatory drawing of the manufacturing method which foam-molds the open cell resin foam using the foaming agent containing nitrogen gas or a carbon dioxide gas of a supercritical state.

Explanation of symbols

  12a ... heat insulation wall of refrigerator box, 12e ... outer plate of box, 12f ... inner plate of box, 13a ... heat insulation wall of refrigerator door, 13f ... inner plate of door, 20 ... vacuum heat insulator, 21 ... Core material, 21a ... adsorbent storage part, 21b ... insertion part, 22 ... adsorbent, 23 ... inner bag, 24 ... outer bag, 25 ... bag body, 31 ... polyol, 32 ... isocyanate, 33 ... mixing head, 36 ... Mold.

Claims (6)

A core material made of an open cell resin foam foamed with a foaming agent containing a gas in a supercritical state;
A vacuum heat insulating material having a gas barrier property and a bag body containing the core material and decompressed inside. A core made of an open-cell resin foam foam-molded with a foaming agent containing nitrogen gas or carbon dioxide gas in a supercritical state;
An adsorbent that adsorbs a gas component generated by the core material;
A bag body containing the core material and the adsorbent and decompressed inside;
The bag body contains the core material and the adsorbent, and the inside bag is sealed by reducing the pressure inside, and the inside bag is housed and the inside is vacuumed and sealed, and gas permeation between the inside and the outside is suppressed. A vacuum heat insulating material comprising an outer bag having gas barrier properties.   3. The vacuum heat insulating material according to claim 1, wherein the core material is made of an open cell polystyrene resin foam obtained by foam molding using nitrogen gas or carbon dioxide gas in a supercritical state as a foaming agent.   The vacuum heat insulating material according to claim 3, wherein a communication rate of the polystyrene resin foam is 99% or more.   3. The vacuum heat insulating material according to claim 1, wherein the resin foam is foam-molded with a mixed foaming agent of supercritical carbon dioxide gas or nitrogen gas and water. In the refrigerator in which a large number of vacuum heat insulating materials are disposed on the outer plate side or the inner plate side of the space formed by the outer plate and the inner plate, and the space other than the vacuum heat insulating material is filled with the foam heat insulating material,
The vacuum heat insulating material has a core material made of an open-cell resin foam foam-molded with a foaming agent containing a gas in a supercritical state, an adsorbent that adsorbs moisture and gas components of the core material, and has a gas barrier property. And a bag body containing the core material and the adsorbent and decompressed inside.

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