Patent Application
20170096284
The present invention relates to a vacuum heat insulating body, and a heat insulating container and a heat insulating wall employing the same.
Recently, from the viewpoint of prevention of global warming, improvement of energy saving is strongly demanded and also becomes an urgent problem in household electric appliances. Particularly, in heat-retaining/cold-keeping equipment such as a refrigerator, a freezer, and a vending machine, from the viewpoint of efficiently utilizing heat, a heat insulating material having excellent heat insulating performance is required.
As general heat insulating materials, materials selected from a fiber material such as glass wool, and a foamed body such as urethane foam are employed. In order to improve the heat insulating performance of the heat insulating materials, the heat insulating material is required to be increased in thickness. However, in a case where there is restriction in a space which is to be filled with the heat insulating material, for example, in a case where space saving is required or the space is required to be effectively used, the heat insulating material cannot be applied.
Therefore, as a high-performance heat insulating material, a vacuum heat insulating material has been proposed. The vacuum heat insulating material is a heat insulating body in which a core material playing a role of a spacer is inserted into an outer packing material having gas barrier properties, the internal pressure is reduced, and the inside is sealed.
Compared to the urethane foam, the vacuum heat insulating material has heat insulating performance 20 times thereof and has excellent characteristics in that even if the thickness is reduced, sufficient heat insulating performance can be obtained.
Therefore, the vacuum heat insulating material satisfies customer's demands desiring increased inner volume of a heat insulating case body and attracts attention as effective means of achieving improvement of energy saving followed by improvement of the heat insulating performance.
For example, in refrigerators, in the heat insulating case body configuring a refrigerator main body, urethane foam is foamed in a heat insulating space between inner and outer cases, thereby filling the heat insulating space. The vacuum heat insulating material is additionally installed in the heat insulating space, the heat insulating properties thereof are enhanced, and the inner volume of the heat insulating case body is increased.
However, in a case of being used in a refrigerator and the like, the heat insulating space of the heat insulating case body generally exhibits a complicated shape. Accordingly, there is limitation in improving the ratio of the area which can be covered with the vacuum heat insulating material, that is, the area of the vacuum heat insulating material occupying in the total heat transfer area of the heat insulating case body.
Therefore, for example, a technology has been proposed. According to the technology, after the heat insulating space of the heat insulating case body is filled with open-cell urethane through a blow-molding air feed port of the heat insulating case body and the open-cell urethane is foamed, the inside of the heat insulating case body is exhausted and evacuated by a vacuum exhaust apparatus connected to the air feed port and the heat insulating case body itself serves as the vacuum heat insulating material (for example, refer to PTL 1).
In addition, similar to PTL 1, this applicant has proposed that the heat insulating space of the heat insulating case body serving as the refrigerator main body is filled with open-cell urethane to be foamed and is subjected to vacuum drawing such that the heat insulating case body itself serves as the vacuum heat insulating material. Moreover, another technology has been proposed. According to the technology, closed cells which are generated when the heat insulating space filled with the open-cell urethane to be foamed and remain in a skin layer in the vicinity of an inner surface of a case body are also caused to be open cells such that the open-cell rate is increased and the heat insulating properties thereof are further improved (for example, refer to PTL 2).
As disclosed in PTL 1 and PTL 2 described above, in the heat insulating case body configured to have the open-cell urethane foam which fills the heat insulating space so as to be foamed and is subjected to vacuum sealing, that is, in a vacuum heat insulating body, as the porosity of the open-cell urethane foam is increased, the surface area inside the open-cell urethane foam increases. Since heat from the outside is transferred along the surface of the open-cell urethane foam, when the surface area increases, the heat insulating properties are improved.
When the open cells are formed in alignment in a moving direction of heat, the heat insulating properties are not improved. However, since cells are disorderedly formed through foaming, there is little possibility that the cells are formed in alignment in the moving direction of heat. Therefore, as the surface area of the inside increases, the heat insulating properties are improved. Therefore, according to the technology disclosed in PTL 2 regarding the vacuum heat insulating body, since the closed cells which remain in the skin layer in the vicinity of the inner surface of the case body can also be caused to be open cells and the surface area thereof can be increased, the heat insulating properties are improved.
As described above, in the vacuum heat insulating body which is disclosed in PTL 2 and is configured to have the open-cell urethane subjected to vacuum sealing, even if the shape of the appearance is complicated as the heat insulating case body, the entire region can be subjected to vacuum heat insulating. Therefore, for example, when the vacuum heat insulating body is employed in refrigerators, the heat insulating case body itself can be reduced in thickness and the inner volume (storage space) can be further increased.
In addition, when the vacuum heat insulating body is applied for the purpose in which the heat insulating properties are strongly expected even though the shape is not complicated, for example, a panel for a heat insulating container such as an LNG storage tank storing an ultra-low temperature substance (for example, liquefied natural gas (LNG)), and a tank of an LNG transport tanker, the wall of the heat insulating container can be reduced in thickness and invasion of heat into the heat insulating container can be effectively restrained. Therefore, in a case of an LNG tank, generation of boil off gas (BOG) can be effectively reduced, and the natural evaporation rate (boil-off rate, BOR) of LNG can be lowered.
However, in the above-described vacuum heat insulating body configured to have the open-cell urethane subjected to vacuum sealing, the hole diameter of the open cell ranges from 30 to 200 μm, which is extremely small. Therefore, there are problems in that it takes times to perform vacuum drawing, productivity is degraded, and the cost increases.
PTL 1: Japanese Patent Unexamined Publication No. 9-119771
PTL 2: Japanese Patent No. 5310928
The present invention has been made in consideration of the problems described above, and there is provided a vacuum heat insulating body in which vacuum drawing efficiency is improved and productivity is enhanced, and a heat insulating container and a heat insulating wall employing the same.
According to the present invention, there is provided a vacuum heat insulating body including a core material, and an outer packing material that vacuum-seals the core material. The core material includes a first heat insulating core material and a second heat insulating core material having ventilation characteristics. The first heat insulating core material has ventilation resistance greater than the ventilation resistance of the second heat insulating core material.
In addition, according to the present invention, there is provided a heat insulating container that can be used as a heat insulating container retaining a substance of which a temperature is 100° C. or much lower than a normal temperature, and the heat insulating container includes the vacuum heat insulating body described above. The vacuum heat insulating body is configured such that a heat insulating core material having low heat conductivity between the first heat insulating core material and the second heat insulating core material is disposed on a low-temperature side in the heat insulating container.
In addition, according to the present invention, there is provided a heat insulating wall that can be used as a heat insulating wall being used in an environment of 0° C. or lower, and the heat insulating wall includes the vacuum heat insulating body described above. The vacuum heat insulating body is configured such that the heat insulating core material having low heat conductivity between the first heat insulating core material and the second heat insulating core material is disposed on the low-temperature side of the heat insulating wall.
Accordingly, when the inside of the heat insulating body is subjected to vacuum drawing, the first heat insulating core material having significant ventilation resistance, for example, an open-cell resin such as open-cell urethane can be reduced in thickness due to the presence of a fiber material such as the second heat insulating core material having small ventilation resistance, for example, glass wool or rock wool. Accordingly, the path formed of open cells is shortened as much as the thickness is reduced, and ventilation resistance is reduced. Thus, the vacuum drawing time can be shortened, and productivity can be improved.
In addition, the gas itself gradually coming out from the inside of the open-cell resin can be reduced as much as the thickness of the first heat insulating core material having significant ventilation resistance is reduced, in accordance with the shortened open-cell path which is shortened due to the reduced thickness thereof. At the same time, the gas can be dispersed in the path in its entirety which is configured with open cells, and deformation caused due to a local pressure rise can also be restrained. Besides since the amount of gas coming out from the first heat insulating core material having significant ventilation resistance is reduced, degradation of the heat insulating properties can also be restrained.
In this manner, according to the present invention, it is possible to provide a vacuum heat insulating body in which vacuum drawing efficiency is improved and productivity is enhanced, and a heat insulating container and a heat insulating wall employing the same.
Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the exemplary embodiments.
First, a first exemplary embodiment of the present invention will be described. In the present exemplary embodiment, description will be given with reference to an example of a case where a heat insulating case body itself in refrigerator 1 is configured with a vacuum heat insulating body. However, the exemplary embodiment is merely an example, and the configuration of the vacuum heat insulating body of the present exemplary embodiment can also be used in a part of a door.
[Configuration of Refrigerator]
First, the configuration of refrigerator 1 of the present exemplary embodiment will be described.
As illustrated in
Partition panel 8 divides the internal space of vacuum heat insulating case body 7 into refrigerating compartment 9 on the upper side and freezing compartment 10 on the lower side. Each of refrigerating compartment 9 and freezing compartment 10 is provided with a door (not illustrated). Similar to the vacuum heat insulating case body described above, these doors are configured by loading core material 5 and gas suction material 6 in the heat insulating space, and then, performing vacuum sealing.
In addition, components (compressor, evaporator, condenser, and the like) corresponding to the cooling principle thereof are attached to refrigerator 1. The internal space of vacuum heat insulating case body 7 is not limited to the example of being divided into two divisions such as refrigerating compartment 9 and freezing compartment 10. For example, the internal space may be divided into multiple storage compartments for different applications (refrigerating compartment, freezing compartment, ice compartment, a vegetable compartment, and the like).
[Configuration of Vacuum Heat Insulating Body]
Subsequently, vacuum heat insulating case body 7 configured to be vacuum-sealed, that is, the configuration of the vacuum heat insulating body will be described by applying
As illustrated in
The open-cell resin which is an example of first heat insulating core material 11 having relatively great ventilation resistance is disclosed in detail in PTL 2 of this applicant, exemplified as the citation literature. Therefore, the disclosure thereof will be cited and detailed description will be omitted. However, in brief, the disclosure is as follows.
In other words, the open-cell resin is configured with open-cell urethane foam which is integrally foamed and fills heat insulating space 4 between outer case 2 and inner case 3, for example, open-cell urethane foam formed through copolymerization reaction. A number of cells present in a core layer at the center of heat insulating space 4 communicate with each other through a first penetration hole. Moreover, cells present in a skin layer in the vicinity of an interface with respect to each of outer case 2 and inner case 3 in heat insulating space 4 communicate with each other through a second penetration hole which is formed of powder having a low affinity with a urethane resin. In this manner, the open-cell resin of the present exemplary embodiment is an open-cell resin in which cells in the entire region communicate with each other through the first penetration hole and the second penetration hole from the core layer to the skin layer.
While heat is insulated between outer case 2 and inner case 3, the open-cell resin configuring first heat insulating core material 11 has functions of supporting outer case 2 and inner case 3 and retaining the shape of vacuum heat insulating case body 7. In other words, first heat insulating core material 11 contributes to improvement of physical properties such as the strength and the rigidity of the vacuum heat insulating body. However, the shape retention force of first heat insulating core material 11 is degraded as the porosity increases. Meanwhile, in first heat insulating core material 11, the heat insulating properties of the open-cell resin are improved as the porosity increases. Therefore, in consideration of the heat insulating properties and the mechanical strength, the porosity of the open-cell resin may be determined. In the present exemplary embodiment, the porosity is set to 95% or greater.
In addition, as cells are small in size, the surface area inside the open-cell resin increases. Therefore, the heat insulating properties are improved. In other words, as cells are small in size, the heat insulating properties of the open-cell resin are improved. Therefore, in the present exemplary embodiment, for the sake of both ensuring the strength and improving the heat insulating properties, the size of cells ranges from 30 μm to 200 μm.
In addition, second heat insulating core material 12 having relatively small ventilation resistance is configured with a fiber material. As second heat insulating core material 12, an inorganic-based fiber material is particularly employed from the aspect of heat insulating performance and the like. Specifically, for example, the inorganic-based fiber material is selected from glass wool fibers, ceramic fibers, slag wool fibers, rock wool fibers, and the like. In the present exemplary embodiment, glass wool fibers (glass fibers having relatively thick fiber diameters) having the average fiber diameter within a range from 4 μm to 10 μm is additionally burned and is employed.
Moreover, the fiber material configuring second heat insulating core material 12 is enclosed in a packing bag material (not illustrated) having ventilation characteristics and is configured to be formed along the shape of heat insulating space 4. The process can be effectively achieved by mixing the fiber material with a binder material. Even in such a case, the fiber material is configured to occupy a ratio ranging from at least 5% to 90%.
In vacuum heat insulating case body 7 configured as described above, first heat insulating core material 11 is disposed so as to face the internal space side serving as the storage compartment of vacuum heat insulating case body 7, and second heat insulating core material 12 is disposed so as to face the outer side, respectively.
[Method of Manufacturing Vacuum Heat Insulating Case Body]
Vacuum heat insulating case body 7 is a vacuum heat insulating body in which a two-layer core material including first heat insulating core material 11 formed of the open-cell resin, and second heat insulating core material 12 formed of the fiber material are vacuum-sealed. As a method of manufacturing vacuum heat insulating case body 7, first, a packing bag material internally having a fiber core material is set inside heat insulating space 4, and urethane liquid is injected through urethane liquid filler ports 13 provided at several appropriate places in outer case 2 or inner case 3 (refer to
As the method of manufacturing vacuum heat insulating case body 7, a method similar to the method disclosed in PTL 2 mentioned above is employed. In addition, before urethane is injected in the method, a step of loading second heat insulating core material 12 in heat insulating space 4 is added. Here, vacuum sealing and the like of heat insulating space 4 may be performed inside the vacuum chamber. The disclosure in PTL 2 is cited for the detail, and detailed description thereof will be omitted.
[Operational effect of Vacuum Heat Insulating Body]
Subsequently, operational effects of vacuum heat insulating case body 7 configured as described above, that is, the vacuum heat insulating body will be described.
Vacuum heat insulating case body 7 has a core material which is vacuum-sealed in heat insulating space 4 in a two-layer structure including first heat insulating core material 11 formed of the open-cell resin, and second heat insulating core material 12 formed of the fiber material. Accordingly, compared to a case of configuring the core material with one layer of an open-cell resin in the related art, the heat insulating performance thereof can be enhanced.
For example, according to an experiment, when heat transfer coefficients λ of a comparative product having only the open-cell urethane core material and a product of the present exemplary embodiment having the two-layer core material including a fiber material and integrally foamed open-cell urethane foam are compared, heat conductivity λ of the comparative product is 0.007 W/mK, and in contrast thereto, heat conductivity λ of the product of the present exemplary embodiment is 0.004 W/mK. This result is caused due to the heat insulating effect of second heat insulating core material 12 formed of the fiber material in addition to the heat insulating effect of the open-cell urethane.
The above-described experimental result is a result obtained by preparing a cuboid-shaped core material having a size of 198×130 and a thickness of 30 mm in a sealed ABS resin container at internal pressure of 10 Pa, and measuring the heat conductivity under the temperature difference of 38° C./10° C. in the thickness direction.
Meanwhile, in the present exemplary embodiment, the cells of the open-cell resin configuring first heat insulating core material 11 range from 30 μm to 200 μm, which is small. Accordingly, when the inside of heat insulating space 4 is subjected to vacuum drawing, there is a possibility that the ventilation resistance (exhaust resistance) of the open-cell resin becomes significant, thereby requiring a long period of time in order to reduce the pressure of the internal space of the open-cell resin.
However, in vacuum heat insulating case body 7 of the present exemplary embodiment, second heat insulating core material 12 formed of the fiber material is loaded inside heat insulating space 4 together with first heat insulating core material 11 formed of the open-cell resin. Accordingly, the thickness of first heat insulating core material 11 can be thinned as much as the thickness of second heat insulating core material 12. As a result thereof, an open-cell path of the open-cell resin configuring first heat insulating core material 11 is as much shortened as the thickness is thinned, the ventilation resistance is reduced, and the vacuum drawing time is shortened. Thus, productivity can be improved.
Here, internal pressure change A in a case of open-cell urethane having a thickness of 30 mm, and internal pressure change B of open-cell urethane having the halved thickness of 15 mm are illustrated. Here, it is understood that the time taken until the internal pressure reaches the same value, for example, 200 Pa is “C” in a case of open-cell urethane A having the thickness of 30 mm, and the time is “D” in a case of open-cell urethane B having the halved thickness of 15 mm, which is shorter.
In addition, in vacuum heat insulating case body 7 of the present exemplary embodiment, the heat insulating core material of the open-cell resin having significant ventilation resistance can be reduced in thickness. Moreover, in accordance with the shortened open-cell path caused due to the reduced thickness, the gas itself gradually coming out from the inside of the open-cell resin can be reduced, and the gas can be dispersed over the path in its entirety configured with the open cells. Accordingly, the heat insulating performance thereof can be as much restrained from being degraded as the gas is reduced, and deformation caused due to the local pressure rise can be as much restrained as the gas is dispersed.
Besides, the glass wool, the rock wool, or the like itself configuring second heat insulating core material 12 of vacuum heat insulating case body 7 has low heat conductivity, thereby having favorable heat insulating properties. Accordingly, even if first heat insulating core material 11 is reduced in thickness, vacuum heat insulating case body 7 can have excellent heat insulating properties. Moreover, as described above, in vacuum heat insulating case body 7, since the amount of the gas coming out from the heat insulating core material such as the open-cell resin having significant ventilation resistance can be reduced, the heat insulating properties can also be restrained from being degraded.
As illustrated in
The experimental result in this case is a result of the pressure measurement performed every day elapsed, by using a spinning rotor gauge with respect to an experiment product obtained by causing a cuboid-shaped core material having a size of 198×130 and a thickness of 30 mm to be exhausted for 30 minutes in a sealed container configured with liquid crystal polymer and an aluminum foil laminate film, by using a mechanical booster pump, and performing heat-welding of a film.
As described above, the heat insulating properties of vacuum heat insulating case body 7 of the present exemplary embodiment can be enhanced due to the two-layer structure including first heat insulating core material 11 formed of the open-cell resin and second heat insulating core material 12 formed of the fiber material. Without inhibiting the heat insulating performance thereof, it is possible to shorten the vacuum drawing time of first heat insulating core material 11 and to improve productivity.
In addition, in vacuum heat insulating case body 7, one side of the heat insulating core material is configured with the open-cell resin, and the other side of the heat insulating core material is configured with the fiber material having ventilation resistance smaller than the ventilation resistance of the open-cell resin heat insulating core material. Accordingly, as described above, the open-cell resin is caused to flow into heat insulating space 4 in a state where the fiber material is input into heat insulating space 4. Then, the open-cell resin and the fiber material are integrally foamed and are subjected to vacuum drawing. It is possible to drastically improve productivity, to reduce the production cost, and to provide a product at a low price.
In addition, in accordance with the configuration in which the fiber material configuring second heat insulating core material 12 is enclosed in the packing bag material having favorable ventilation characteristics, the fiber material which is flexible and easily loses its shape can be easily loaded inside heat insulating space 4. Accordingly, productivity can be further improved and cost reduction can be achieved. In addition, even if vacuum heat insulating case body 7 has a complicated shape, the heat insulating core material can be disposed along the shape, and thus, the heat insulating core material can also cope with a heat insulating structure body having a complicated shape.
In addition, in the present exemplary embodiment, gas suction material 6 is vacuum-sealed inside vacuum heat insulating case body 7 together with core material 5. Accordingly, gas which is contained in the open-cell resin forming first heat insulating core material 11 and is gradually released, and gas which is remaining in second heat insulating core material 12 can be suctioned by gas suction material 6. As a result thereof, a rise of the internal pressure caused due to the gas can be reliably restrained, and deformation of vacuum heat insulating case body 7 can be prevented. At the same time, the heat insulating properties thereof can be favorably maintained over a long period of time. Particularly, in the present exemplary embodiment, gas suction material 6 is disposed on the open-cell resin side configuring first heat insulating core material 11 (refer to
As described above, gas suction material 6 plays a role of suctioning mixed gas of water vapor, air, and the like which remains in or enters a sealed space such as heat insulating space 4, and gas suction material 6 is not particularly limited. For example, a chemically suctioned substance such as calcium oxide and magnesium oxide, a physically suction substance such as zeolite, or a mixture thereof can be used. In addition, copper ion-exchanged ZSM-5 type zeolite having suctioning performance with both chemical suctioning properties and physical suctioning properties and having a significant suctioning capacity can also be used.
In the present exemplary embodiment, gas suction material 6 containing the copper ion-exchanged ZSM-5 type zeolite described above is employed. Accordingly, even if the open-cell resin in which gas tends to be continuously released as time elapses is employed as the core material, gas is reliably and continuously suctioned over a long period of time due to the high suctioning performance and the significant suctioning capacity which the copper ion-exchanged ZSM-5 type zeolite has. Thus, it is possible to reliably prevent a rise of the internal pressure of vacuum heat insulating case body 7 and restrain degradation of the heat insulating properties over a long period of time.
Moreover, as the fiber material configuring second heat insulating core material 12, the inorganic-based fiber material such as glass wool and rock wool is employed. Accordingly, the amount of generated moisture is maintained to be low, and thus, the heat insulating properties can be favorably retained. In other words, since the inorganic-based fiber itself has low water-absorbing properties (hygroscopic properties), the amount of moisture inside vacuum heat insulating case body 7 can be maintained to be low. Accordingly, suctioning ability of gas suction material 6 can be restrained from being reduced due to suctioned moisture, and gas suction material 6 can conduct a favorable function of suctioning gas, thereby having favorable heat insulating performance.
In addition, since the inorganic-based fiber is burned, for example, even in a case where vacuum heat insulating case body 7 is damaged due to some sort of influence, the fiber material does not greatly swell, and the shape can be retained as vacuum heat insulating case body 7. For example, when sealing is performed without burning the inorganic-based fiber, even though it may depend on other conditions, swelling of vacuum heat insulating case body 7 at the time of damage can become two to three times before being damaged. In contrast, when the inorganic-based fiber is burned, expansion at the time of damage can be restrained within 1.5 times, and thus, expansion at the time of damage can be effectively restrained, and dimension-retention properties can be enhanced.
In vacuum heat insulating case body 7 configured as described above, first heat insulating core material 11 is disposed so as to face the internal space of vacuum heat insulating case body 7, that is, the internal space side serving as the storage compartment. Accordingly, vacuum heat insulating case body 7 can be more efficiently heat-insulated, and the heat insulating properties thereof can be enhanced. The open-cell urethane foam configuring first heat insulating core material 11 which is subjected to vacuum drawing has heat conductivity λ lower than heat conductivity λ of the glass wool, the rock wool, or the like configuring second heat insulating core material 12 which is similarly subjected to vacuum drawing. Therefore, according to the disposition configuration described above, firstly, first heat insulating core material 11 having low heat conductivity λ strongly performs heat insulating of a low temperature from the internal space, and second heat insulating core material 12 positioned outside thereof performs heat insulating at a low-temperature region where the temperature is relatively high, after heat insulating is strongly performed by first heat insulating core material 11 having low heat conductivity λ. Accordingly, even second heat insulating core material 12 having slightly high heat conductivity λ can strongly perform heat insulating, and thus, cold air inside the vacuum heat insulating case body can be efficiently heat-insulated and preserved by utilizing heat insulating characteristics thereof.
[Examples of Structure of Vacuum Heat Insulating Body and Method of Manufacturing Same]
According to the configuration of
In addition, in the configuration of
In the configurations of
In
In addition, according to the configuration of
In addition, according to the configuration of
The configuration of
Subsequently,
Subsequently, a second exemplary embodiment of the present invention will be described.
In the present exemplary embodiment, description will be given regarding an example of employing the vacuum heat insulating body in the heat insulating structure body of an LNG inboard tank in an LNG transport tanker.
In
First heat insulating case 25 which is the heat insulating structure body disposed between in-container vessel 24 and intermediate vessel 23 is configured with wooden case frame body 26 such as a plywood plate of which one surface is open, and powder heat insulating material 27 such as pearlite with which the inside of case frame body 26 is filled. Powder heat insulating material 27 may be configured with glass wool or the like, instead of pearlite. In the present exemplary embodiment, description will be given on the assumption that pearlite is employed as the powder heat insulating material.
Similar to first heat insulating case 25, in second heat insulating case 28 disposed between intermediate vessel 23 and extra-container vessel 22, vacuum heat insulating body 29 is laid on the bottom surface of wooden case frame body 26 of which one surface is open, and the opening side part is configured to be filled with powder heat insulating material 27 such as pearlite similar to first heat insulating case 25.
In addition, in the present exemplary embodiment, second heat insulating case 28 is disposed such that vacuum heat insulating body 29 faces the outer side, that is, extra-container vessel 22 side.
Vacuum heat insulating body 29 of the second exemplary embodiment also exhibits an effect similar to vacuum heat insulating case body 7 described in the first exemplary embodiment. The overlapping description of the effect will be omitted. However, in a case where vacuum heat insulating body 29 is employed as the heat insulating material of the LNG inboard tank, metal thin plate 30 serving as the outer packing material that vacuum-seals core material 5 has remarkably high corrosion-resistant performance compared to laminated sheet outer packing materials which have been present in the related art and having a general aluminum-deposited layer. Accordingly, for example, even if vacuum heat insulating body 29 is exposed to sea water, vacuum heat insulating body 29 can be prevented from being corroded and leading to bag-tearing or damage, and thus, there is an advantage that the reliability thereof can be enhanced.
In addition, since core material 5 has the two-layer structure including first heat insulating core material 11 formed of the open-cell resin and second heat insulating core material 12 formed of the fiber material such as glass wool, the heat insulating performance thereof is high. Therefore, the amount of powder heat insulating material 27 inside second heat insulating case 28 employing vacuum heat insulating body 29 can be reduced and second heat insulating case 28 itself can be reduced in thickness, the capacity of heat insulating container 21 can be as much increased as the reduction.
Moreover, similar to the first exemplary embodiment, vacuum heat insulating body 29 employed as the heat insulating material of the LNG inboard tank is disposed such that first heat insulating core material 11 thereof is on a side facing the internal space of in-container vessel 24, that is, the internal space in which a substance such as LNG is stored. Accordingly, heat insulating container 21 can be more efficiently heat-insulated, and the heat insulating properties thereof can be enhanced. In other words, according to such a configuration, as described above, firstly, first heat insulating core material 11 having low heat conductivity λ strongly performs heat insulating of a low temperature from the internal space, and second heat insulating core material 12 positioned outside thereof performs heat insulating at a low-temperature region where the temperature is relatively high, after heat insulating is strongly performed by first heat insulating core material 11 having low heat conductivity λ. Accordingly, even second heat insulating core material 12 having slightly high heat conductivity λ can strongly perform heat insulating, and thus, cold air inside the vacuum heat insulating case body can be efficiently heat-insulated and preserved by utilizing heat insulating characteristics thereof. Particularly, the example of the present exemplary embodiment is effective since the temperature of the substance such as LNG stored in heat insulating container 21 is −162° C., which is an ultra-low temperature.
Moreover, since ZSM-5 type zeolite employed as gas suction material 6 has a chemical suctioning effect, the suctioned gas does not easily leave. Accordingly, the degree of vacuum inside vacuum heat insulating body 29 can be favorably retained. Accordingly, in a case of handling flammable fuel or the like such as LNG, even if the gas suction material suctions flammable gas due to some sort of influence, the gas is not released again due to the influence thereafter such as a rise of temperature, or the like. Thus, explosion-proof properties of vacuum heat insulating body 29 can be enhanced and safety can be improved.
As described above, the forms illustrated in the first exemplary embodiment and the second exemplary embodiment provide a high-quality vacuum heat insulating body having high heat insulating performance at a low price. However, the present invention is not limited to these examples, and various changes can be made within the range in which the object of the present invention is achieved.
For example, in each of the exemplary embodiments described above, vacuum heat insulating case body 7 of refrigerator 1 and vacuum heat insulating body 29 of heat insulating container 21 for an LNG hull tank are described as examples. However, the vacuum heat insulating body, and the configuration and the shape of the heat insulating structure body in which the vacuum heat insulating body is applied are not limited thereto. In other words, instead of the shape of a container, the heat insulating structure body may be employed as a heat insulating wall or the like such as a door which is substantially flat plate-shaped. In addition, as long as the heat insulating structure body is a container, the heat insulating structure body is not necessarily limited to a tank for an LNG hull. For example, the heat insulating structure body may be applied to a housing of a portable cooling box, a housing of a thermostatic oven, a housing of a hot water storage tank, and the like.
In addition, in all of the exemplary embodiments described above, the examples in which the open-cell urethane foam is employed as the open-cell resin are illustrated. However, the open-cell resin of the present invention is not limited thereto. For example, a copolymer resin or the like containing any one of open-cell phenolic foam, and open-cell urethane foam and open-cell phenolic foam may be employed. It is effective if the open-cell resin is an open-cell resin which is disclosed in Japanese Patent No. 5310928 described above and in which cells are formed in both the core layer and the skin layer. However, an open-cell resin which employs only the core layer and in which the skin layer that is a general skin layer of the open-cell resin having no open cell is removed may be employed. Similarly, as the heat insulating material having ventilation resistance smaller than the ventilation resistance of the open-cell resin, an inorganic-based fiber material such as glass wool is exemplified. However, the present invention is not limited to this example. Known organic-based fibers other than the inorganic-based fiber may be employed, and a powder material such as pearlite may be employed.
Moreover, as the outer packing material of the vacuum heat insulating body, a material configured with an assembly of a metal outer case and a resin inner case, and a material configured with an assembly of metal thin plates are exemplified. However, the present invention is not limited to the examples. A resin molded product may be employed. For example, laminated sheet 31 illustrated in
Laminated sheet 31 is obtained by integrally laminating surface protective layer 32, gas barrier layer 33, and heat-welded layer 34. Surface protective layer 32 is selected from a nylon film, a polyethylene terephthalate film, a polypropylene film, and the like. In contrast to metal foil selected from aluminum foil, copper foil, stainless steel foil, and the like, and a resin film serving as a base material, gas barrier layer 33 is formed of a deposited film in which metal or metal oxide is deposited, a film obtained by further performing known coating processing on the surface of the deposited film, or the like. Heat-welded layer 34 is formed of a thermoplastic resin film or the like such as low- density polyethylene.
Subsequently, a third exemplary embodiment of the present invention will be described.
[Configuration of Refrigerator]
The configuration of refrigerator 101 of the present exemplary embodiment will be described.
As illustrated in
Partition panel 108 divides the internal space of vacuum heat insulating case body 107 into refrigerating compartment 110 on the upper side and freezing compartment 109 on the lower side. Freezing compartment 109 is provided in two stages, and another refrigerating compartment 110 is additionally provided below freezing compartment 109. Each of refrigerating compartment 110 and freezing compartment 109 is provided with door 125. Vacuum heat insulating case body 113 of the present exemplary embodiment is configured in the heat insulating space of door 125.
In addition, components (compressor 117, evaporator 118, evaporating dish 119, and the like) corresponding to the cooling principle thereof are attached to refrigerator 101. The internal space of vacuum heat insulating case body 107 is not limited to the example described above. For example, the internal space may be divided into multiple storage compartments for different applications (refrigerating compartment, freezing compartment, ice compartment, a vegetable compartment, and the like).
[Configuration of Vacuum Heat Insulating Body]
Subsequently, vacuum heat insulating case body 113 of the present exemplary embodiment, that is, the configuration of the vacuum heat insulating body will be described.
As illustrated in
First, in the comparative example illustrated in
Subsequently, as illustrated in
Subsequently, as illustrated in
Here, in the second example, description will be given regarding the reason that polyethylene film 123 (interposition) is disposed between open-cell urethane foam 121 which is an example of a first heat insulating core material, and fiber material 122 which is an example of a second heat insulating core material.
As described in the first exemplary embodiment, in the method of manufacturing vacuum heat insulating case body 113, firstly, the packing bag material internally having fiber material 122 is set inside the heat insulating space between outer case 102 and inner case 103. Thereafter, the urethane liquid is injected. In this case, depending on the conditions, the urethane liquid enters a space between the fibers of the fiber core material, a boundary layer is formed, and the gas inside thereof cannot be exhausted well. As a result thereof, there is a possibility that the heat insulating performance cannot be conducted well. In order to prevent such a case, there is provided a configuration in which the first heat insulating core material and the second heat insulating core material are physically separated from each other by the interposition in order to cause the core materials to exhibit performance individually and sufficiently.
Subsequently, as illustrated in
As described above, according to the configuration of the second example, it is possible to prevent a phenomenon in which the urethane liquid enters a space between the fibers of the fiber core material due to the disposed interposition so that the gas therein cannot be exhausted well. However, since polyethylene film 123 (interposition) does not have ventilation characteristics, air cannot pass through between the first heat insulating core material and the second heat insulating core material. Accordingly, on the contrary, there is a possibility that the interposition may hinder the exhaust from the vacuum heat insulating body. Therefore, in this example, penetration hole 124 is provided in order to cause the interposition to have slight ventilation characteristics.
In the first example to the third example described above, the example in which open-cell urethane foam 121 and fiber material 122 covered with gas barrier layer 131 are configured in the heat insulating space inside outer case 102 and inner case 103 serving as the outer packing material of vacuum heat insulating case body 113 is illustrated. In each of the examples, the example in which the first heat insulating core material and the second heat insulating core material are disposed in the entire region of the heat insulating space in the width direction is illustrated. However, the present invention is not limited to this example.
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[Method of Manufacturing Vacuum Heat Insulating Case Body]
Subsequently, a method of manufacturing vacuum heat insulating case body 113 of the present exemplary embodiment will be described.
First, each of inner case 103 and outer case 102 is manufactured by preparing a sheet having gas barrier properties and molding the sheet (S301 to S304).
In addition, separately, the urethane liquid is injected into a mold and is caused to be foamed (S305). Fiber material 122 (for example, glass wool) is added. In this case, as necessary, the interposition can be present between the first heat insulating core material and the second heat insulating core material by wrapping fiber material 122 with polyethylene film 123, or sandwiching polyethylene film 123. Thereafter, mold-release from the mold is performed (S307).
Inner case 103, outer case 102, and open-cell urethane foam 121 prepared as described above are assembled (S308), and inner case 103 and outer case 102 are welded to each other, thereby retaining air-tight properties (S309). The inside of inner case 103 and outer case 102 is subjected to vacuum drawing, or inner case 103 and outer case 102 in their entirety are input into the vacuum chamber and are subjected to vacuum drawing (S310), and the part of the port of the exhaust pipe subjected to vacuum drawing is tightly sealed (S311). Accordingly, the vacuum heat insulating body can be manufactured.
[Operational Effect of Vacuum Heat Insulating Body]
Subsequently, vacuum heat insulating case body 113 which is prepared as described above, that is, an operational effect of the vacuum heat insulating body will be described.
As illustrated in
In contrast, in the second example (configuration including the interposition between the first heat insulating core material and the second heat insulating core material) and the third example (configuration having penetration hole 124 bored in the interposition), the internal pressures are respectively equal to or lower than the internal pressure of the comparative example and equal to or lower than half the internal pressure of the comparative example. Thus, it is possible to mention that practicality is high. In the present exemplary embodiment, in the second example and the third example, the interposition is polyethylene film 123 having a thickness of 100 μm, and in the third example, the hole diameter of penetration hole 124 is the diameter of 1.0 mm, and the pitch is 10 mm.
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In contrast, in the second example (configuration including the interposition between the first heat insulating core material and the second heat insulating core material) and the third example (configuration having penetration hole 124 bored in the interposition), the internal pressures are equal to or lower than half the internal pressure of the comparative example.
Here, in the example of
Subsequently, an optimal configuration in the third example in a case where polyethylene film 123 which is an example of the interposition of the vacuum heat insulating material of the present exemplary embodiment is employed, that is, in a case where penetration hole 124 is included will be examined.
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In other words, when the thickness of the interposition is set to range from 30 to 500 μm, the configurations of the second example and the third example can conduct more performance compared to the thickness before and after thereof.
Subsequently, an optimal hole diameter in the third example in a case where polyethylene film 123 which is an example of the interposition of the vacuum heat insulating material of the present exemplary embodiment is employed, that is, in a case where penetration hole 124 is included will be examined.
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In this manner, for those skilled in the art, according to the description of each of the exemplary embodiments, it is clear that various modifications of the present invention and other exemplary embodiments can be made. Therefore, the description of each of the exemplary embodiments should be interpreted as only an example and is provided for the purpose of instructing those skilled in the art regarding preferable forms to execute the present invention. Without departing from the idea of the present invention, at least any detail of the structure and the function can be substantially changed.
As described above, the vacuum heat insulating body of the exemplary embodiments of the present invention includes the core material, and the outer packing material that vacuum-seals the core material. The core material includes first heat insulating core material 11 and second heat insulating core material 12 having ventilation characteristics, and first heat insulating core material 11 has ventilation resistance greater than the ventilation resistance of second heat insulating core material 12.
According to such a configuration, when the inside of the heat insulating body is subjected to vacuum drawing, the first heat insulating core material having significant ventilation resistance, for example, an open-cell resin such as open-cell urethane can be reduced in thickness due to the presence of a fiber material such as the second heat insulating core material having small ventilation resistance, for example, glass wool or rock wool. The path formed of open cells is shortened as much as the thickness is reduced, and ventilation resistance is reduced. Thus, the vacuum drawing time can be shortened, and productivity can be improved.
In addition, the gas itself gradually coming out from the inside of the open-cell resin can be reduced as much as the thickness of the first heat insulating core material having significant ventilation resistance is reduced, in accordance with the shortened open-cell path which is shortened due to the reduced thickness thereof. At the same time, the gas can be dispersed in the path in its entirety which is configured with open cells, and deformation caused due to a local pressure rise can also be restrained. Besides, since the amount of gas coming out from the heat insulating core material such as the first open-cell resin having significant ventilation resistance is reduced, degradation of the heat insulating properties can also be restrained.
In addition, the first heat insulating core material may be configured with the open-cell resin, and the second heat insulating core material may be configured with the fiber material or the powder material having ventilation resistance smaller than the ventilation resistance of the open-cell resin.
Accordingly, the heat insulating body can be prepared by causing the open-cell resin to flow into the packing bag material in a state where the fiber material or the powder material is input into the packing bag material, and causing the open-cell resin, and the fiber material or the powder material to be integrally foamed and to be subjected to vacuum drawing. Accordingly, productivity can be drastically improved, the production cost can be reduced, and the heat insulating body can be provided at a lower price.
In addition, the interposition that is disposed at a boundary between the first heat insulating core material and the second heat insulating core material may be configured to be further included.
According to such a configuration, when the open-cell resin is foamed, liquid before being foamed can be prevented from permeating the fiber material or the powder material. When the liquid before being foamed permeates, the boundary layer causing deterioration of the heat insulating performance is formed. In this case, the fiber material or the powder material may be in a state of being packed so as to have a bag form.
In this manner, without inhibiting the filling properties of the open-cell resin, the outer packing material in its entirety can be filled.
In addition, the interposition may be configured to be a resin sheet or a resin film.
When such a resin is employed, a heat leak can be restrained, and the heat insulating performance is not inhibited.
In addition, the resin sheet or the resin film may be configured to be a resin having no functional group.
According to such a configuration, when a resin having no functional group (for example, OH group) is employed, it is possible to prevent deterioration of the heat insulating performance caused due to a new boundary layer formed with respect to the first heat insulating core material.
In addition, the thickness of the resin sheet or the resin film may be configured to range from 30 to 500 μm.
As the thickness of the interposition is increased, the heat conductivity is enhanced. Specifically, when the thickness is increased to be greater than 500 μm, there is an influence of degradation of the heat insulating performance. On the contrary, when the interposition is excessively thinned, specifically when the thickness is decreased to be smaller than 30 μm, there is a possibility that the film may be broken due to the foam pressure when the open-cell resin is foamed. In other words, when the thickness of the interposition ranges from 30 to 500 μm, more performance can be conducted compared to the thickness before and after thereof.
In addition, the penetration hole that is formed in the resin sheet or the resin film may be configured to be further included.
According to such a configuration, the second heat insulating core material having small ventilation resistance and the first heat insulating core material can ventilate through the penetration hole. Therefore, when vacuum exhaust is performed, exhaust of the first heat insulating core material can be efficiently performed through the second heat insulating core material having small ventilation resistance, and the penetration hole.
In addition, the diameter of the penetration hole may range from 0.1 to 4 mm.
When the diameter of the penetration hole is smaller than 0.1 mm, there is no improvement of the exhaust efficiency. When the diameter exceeds 4 mm, there is a possibility that the first heat insulating core material permeates the second heat insulating core material. When the diameter ranges from 0.3 to 2 mm, efficiency of the exhaust can be further improved.
In addition, there may be provided multiple penetration holes, and the pitch between each of the multiple penetration holes may be configured to range from 2 to 90 mm.
When the pitch is smaller than 2 mm, the strength of the film is weakened, and there is a possibility that the film may be broken due to the foam pressure when the first heat insulating core material is foamed. In addition, when the pitch exceeds 90 mm, there is no effect of improving the exhaust efficiency.
In addition, the outer packing material may include the inner case and the outer case, and the first heat insulating core material may be configured to be disposed on the inner case side.
Accordingly, the inner case of the vacuum heat insulating body can be configured to be a curved surface other than a flat surface. The reason is that the first heat insulating core material is more flexibly deformed so as to fill the inside of the space. Accordingly, in a case of being employed in the heat insulating body or the heat insulating wall, it is possible to prevent degradation of the heat insulating properties caused due to the gap between the vacuum heat insulating body and the appearance component or the like.
In addition, the exhaust hole may be configured to be provided from a surface of the first heat insulating core material toward the second heat insulating core material.
According to such a configuration, the position of the exhaust port can be freely provided, and the open-cell resin having significant ventilation resistance can be efficiently exhausted from the periphery by employing the exhaust hole.
In addition, the diameter of the exhaust hole may be configured to range from 1 to 5 mm.
When the diameter of the exhaust hole is smaller than 0.3 mm, there is no improvement of the exhaust efficiency, and when the diameter exceeds 5 mm, there is a possibility of causing degradation of the heat insulating performance.
In addition, there may be provided multiple exhaust holes, and a pitch between the multiple exhaust holes may be configured to be equal to or greater than 1 mm.
When the pitch is smaller than 1 mm, there is a possibility of causing degradation of the compressive strength. Meanwhile, when the pitch is equal to or greater than 1 mm, it is possible to exhibit the effect of the provided exhaust hole without having deformation of the container even after vacuum drawing is performed.
In addition, the second heat insulating core material may be loaded in the packing bag material, and the packing bag material may be configured with the interposition.
According to such a configuration, in the configuration including the interposition, the interposition can also be employed as a packing material packing the second heat insulating core material.
In addition, the fiber material may be configured with the inorganic fiber material containing glass wool or rock wool.
Accordingly, remaining gas from the fiber material released inside the vacuum heat insulating body is reduced. Thus, degradation of the degree of vacuum can be restrained, and the water-absorbing properties (hygroscopic properties) of the fiber material itself can be lowered. Therefore, the amount of moisture inside the vacuum heat insulating body can be maintained to be low, and the heat insulating properties can be further improved.
In addition, the outer packing material may internally include the gas suction material which is sealed together with the core material, and the gas suction material may be configured to be disposed on the first heat insulating core material inside the outer packing material.
According to such a configuration, when gas remaining inside the outer packing material is suctioned, the gas which is left behind vacuum drawing, remains inside the open-cell resin, and gradually comes out from the open-cell resin can be efficiently suctioned by the gas suction material. Therefore, it is possible to prevent the heat insulating body from being deformed and to prevent the heat insulating properties from being degraded in accordance with a rise of the internal pressure caused by the gas from the open-cell resin.
In addition, the outer packing material may be configured with a pair of metal thin plates, and may be configured by fixedly attaching the circumferential edges of the pair of metal thin plates to each other and performing vacuum-sealing of the inside.
Accordingly, in a metal thin plate-made outer packing material which vacuum-seals the core material has remarkably high corrosion-resistant performance compared to a multi-layer outer packing material including an aluminum-deposited layer of a general vacuum heat insulating material. Therefore, even in a corrosive environment, for example, even if the outer packing material is employed as the heat insulating wall of an LNG tanker and the like and is exposed to sea water, it is possible to prevent the outer packing material from being corroded and damaged and to significantly improve the reliability thereof.
In addition, the heat insulating container of the exemplary embodiment may be a heat insulating container retaining a substance of which a temperature is 100° C. or much lower than a normal temperature. The heat insulating container may include the vacuum heat insulating body described above, and the vacuum heat insulating body may be configured such that the heat insulating core material having low heat conductivity between the first heat insulating core material and the second heat insulating core material is disposed on the low-temperature side of the heat insulating container. In this description, “normal temperature” denotes an atmospheric temperature.
Accordingly, firstly, the heat insulating core material having low heat conductivity strongly performs heat insulating of a low temperature from a low-temperature substance, and the heat insulating core material positioned outside thereof performs heat insulating at the low-temperature region where the temperature is relatively high, after heat insulating is strongly performed by the heat insulating core material having low heat conductivity. Accordingly, a substance inside the container can be efficiently heat-insulated and preserved by utilizing heat insulating characteristics thereof.
In addition, the heat insulating wall of the exemplary embodiment may be a heat insulating wall that is used in an environment of 0° C. or lower. The heat insulating wall may include the vacuum heat insulating body described above, and the vacuum heat insulating body may be configured such that a heat insulating core material having low heat conductivity between the first heat insulating core material and the second heat insulating core material is disposed on a low-temperature side in the heat insulating wall.
Accordingly, firstly, the heat insulating core material having low heat conductivity strongly performs heat insulating of a low temperature from a low-temperature substance, and the heat insulating core material positioned outside thereof performs heat insulating of the low-temperature region where the temperature is relatively high, after heat insulating is strongly performed by the heat insulating core material having low heat conductivity. Accordingly, efficient heat insulating can be performed by utilizing heat insulating characteristics thereof.
As described above, according to the present invention, it is possible to provide a high-quality vacuum heat insulating body having high heat insulating performance at a low price, specifically to exhibit a remarkable effect of improving the vacuum drawing efficiency and enhancing the productivity. Therefore, the present invention can be widely applied to a vacuum heat insulating body from consumer appliances such as a refrigerator to industrial use such as an LNG storage tank, and a heat insulating container and a heat insulating wall employing the same, thereby being useful.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-114565 | Jun 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/002773 | 6/2/2015 | WO | 00 |
