JP2006125527A - Vacuum thermal insulation panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum thermal insulation panel capable of maintaining excellent heat insulating property for a long period by a proper highly accurate and highly reliable measurement method for heat conductance when the vacuum thermal insulation panel is used as a measured object in the method for measuring the heat conductance of the measured object by generating heat between the measured object and a heat resistance material, flowing the heat in the measured object and the heat resistance material, and measuring the heat conductivity of the measured object by using a temperature difference between at least two positions of the heat resistance material and also provide a refrigerator less consuming an electric power. <P>SOLUTION: A projected flat part 15 or a recessed flat part 16 having such a size that involves a circle of 50 mm in diameter and an irregularity of within 0.1 mm is disposed on the vacuum thermal insulation panel 11 and a thermal conductivity measuring device 21 is disposed on the projected flat part 15 or the recessed flat part 16, and then the heat conductivity is measured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a shape of a vacuum heat insulating panel used for a refrigerator or the like and a method for measuring the thermal conductivity thereof.

  In recent years, from the viewpoint of global warming, the necessity of reducing the power consumption of home appliances has been screamed. In particular, a refrigerator is a product that consumes a particularly large amount of power consumption among household electrical appliances, and reducing the power consumption of the refrigerator is indispensable as a measure against global warming. If the load in the refrigerator is constant, the power consumption of the refrigerator is largely determined by the heat insulation performance related to the efficiency of the compressor for cooling the refrigerator and the amount of heat leakage from the refrigerator. In this technical development, it is necessary to improve the efficiency of the compressor and the performance of the heat insulating material. As an example of improving the performance of a heat insulating material, use of a vacuum heat insulating panel in which a core material is covered with a jacket material made of a gas barrier film and the inside is sealed under reduced pressure has been used. The thermal conductivity performance of the vacuum heat insulation panel is one of the parameters that directly affects the power consumption of the refrigerator, and the power consumption is reduced in the refrigerator equipped with the vacuum heat insulation panel causing the vacuum leak. Is impossible. Therefore, it is necessary for the vacuum heat insulation panel to confirm the performance by performing the thermal conductivity measurement before it is assembled in the refrigerator. Conventionally, the thermal conductivity is measured by the plate comparison method of JIS A1412, that is, the test specimen and the standard plate are overlapped to give a temperature difference, the surface temperature difference is measured, and the ratio and the thermal conductivity of the standard plate are calculated. This is done by determining the thermal conductivity of the specimen. Moreover, in the case of a vacuum heat insulation panel, it measures by what is called a reverse vacuum method which puts a vacuum heat insulation panel in containers, such as a chamber, and is evacuated, and visually inspects the swelling of a vacuum heat insulation panel. However, since the plate comparison method requires a long time to measure, it is not suitable for 100% inspection of products by mass production.In addition, the reverse vacuum method cannot accurately measure the thermal conductivity, and the air gradually flows. When entering, it is difficult to judge visually.

  In the latest measurement of the thermal conductivity of a conventional vacuum heat insulation panel, there is one disclosed in Japanese Patent Application Laid-Open No. 2002-131257. The thermal conductivity measurement method of the vacuum heat insulation panel shown here generates heat between the object to be measured and the heat resistance material, and flows heat inside the object to be measured and inside the heat resistance material. The thermal conductivity of the object to be measured is obtained from the temperature difference between at least two points.

JP 2002-131257 A

  However, only the method for measuring the thermal conductivity of the vacuum heat insulation panel according to the patent literature cannot cope with the measurement of the thermal conductivity of all the vacuum heat insulation panels. In the method for measuring the thermal conductivity of a vacuum heat insulation panel according to this document, the interface between the object to be measured and the heat generating device that is in direct contact with the object to be measured needs to be in contact with no gap. If there is a gap between the object to be measured and the heat generating device, when heat is generated from the heat generating device, the air in the gap is heated instead of the object to be measured, and appropriate thermal conductivity measurement is performed. Can not do. In order to cope with the thermal conductivity measurement method according to the patent literature, it is necessary to produce a flat core material that eliminates the gap at the contact interface between the heat generator and the object to be measured. In recent vacuum insulation panels, a laminate of short glass fiber materials as the core material has become mainstream. To produce a core material with a flat surface, short glass fiber materials, binders, etc. are used. The method used to make a board must be adopted. However, there is a problem that by adopting a method of forming a board using a binder or the like, the thermal conductivity is improved and the role as a heat insulating material cannot be achieved. Moreover, in the vacuum heat insulation panel using the core material whose surface is not flat, there existed a subject that appropriate thermal conductivity measurement of a vacuum heat insulation panel could not be performed for the reason mentioned above.

  The purpose of the present invention is to arrange a convex or concave flat part on a vacuum heat insulation panel, and place the thermal conductivity measuring device shown in the patent document on the flat part to perform measurement, The heat conductivity measurement is made an appropriate method with higher accuracy and reliability, and as a result, a vacuum insulation panel capable of maintaining excellent thermal insulation performance over a long period of time is provided, and a refrigerator with low power consumption is further provided. There is.

  In order to achieve the above object, the present invention provides a vacuum heat insulating panel comprising a core material, an adsorbing member that adsorbs water vapor and organic gas, and an outer packaging material made of a gas barrier film, and has a convex shape on the vacuum heat insulating panel. Alternatively, a concave flat portion is provided.

  According to the present invention, heat is generated between the object to be measured and the heat resistance material, and heat is caused to flow inside the object to be measured and the heat resistance material, and the object to be measured is obtained from a temperature difference between at least two locations of the heat resistance material. In the thermal conductivity measurement method characterized in that the thermal conductivity of the vacuum thermal insulation panel is determined by using a vacuum thermal insulation panel provided with a convex or concave flat part as an object to be measured. By providing a rate measuring device and making the measurement, the thermal conductivity measurement is made an appropriate method with higher accuracy and reliability, and as a result, a vacuum insulation panel that can maintain excellent thermal insulation performance over a long period of time is provided Furthermore, it is to provide a refrigerator with low power consumption.

[Example 1]
Hereinafter, the vacuum heat insulation panel of one Example of this invention is demonstrated using FIG. The vacuum heat insulation panel shown in the present invention can be applied to vending machines, product display shelves, product display cases, cold storage, cooler boxes, refrigeration / freezer cars, etc., in addition to household and commercial refrigeration / freezers. .

  The vacuum heat insulation panel 11 includes a core material 2, an adsorbing member 3, and an outer covering material 4 that houses the core material 2 and the adsorbing member 3 and is made of a gas barrier film. The vacuum heat insulating panel 11 is formed by decompressing the inside of the jacket material 4 and heat-sealing the peripheral portion of the jacket material 4 with the core material 2 and the adsorbing member 3 inserted into the jacket material 4. It is produced by sealing. The shape of the vacuum heat insulation panel 11 is not specifically limited, The thing of various shapes and thickness is applicable according to the location and workability | operativity applied.

  For example, a core material with a binder produced by bonding a short glass fiber material having an average fiber diameter of 2 μm or more and 4 μm or less with a boric acid binder and performing an aging treatment at 200 ° C. or more for 1 hour is used as the core material 2. Used. By the aging treatment, it is possible to remove a trace amount of water adhering to the core material with the binder. In addition, you may make it produce a core material with a binder by adhere | attaching a glass short fiber material with an average fiber diameter of 2 micrometers or more and 4 micrometers or less with a water glass binder, and performing an aging process at 200 degreeC or more for 1 hour.

  In the case of a core material with a binder, water vapor and gas are easily adsorbed. Therefore, for the purpose of dehydration and degassing of the core material with the binder, it is effective to perform aging of the core material with the binder before insertion into the jacket material 4. The heating temperature at this time is desirably 110 ° C. or higher, and more preferably 180 ° C. or higher, because it is possible to remove the adhering water as a minimum. As a result of examining the moisture content and water absorption rate, etc. for the optimum aging treatment temperature, the moisture content of the core material with the binder is reduced to 1/70 of the core material without the binder treatment in the aging treatment at 180 ° C. × 1 hour. It has been found that the water absorption is decreased and the water absorption is less than that at 110 ° C. for 1 hour. Therefore, it is more preferable that the aging temperature of the core material with the binder is 180 ° C. or higher.

  Further, as another example, the core material 2 is made of a polyethylene short fiber material having an average fiber diameter of 2 μm or more and 4 μm or less and an adsorbing member 3 inserted into a polyethylene bag and compressed with a press machine. A binderless core material produced by temporarily sealing the bag insertion opening is used. In the case of a binderless core material, it has been found that water vapor and gas are difficult to adsorb as compared with a core material with a binder. However, in order to shorten the time required for vacuum sealing and to eliminate the factor of lowering the degree of vacuum in the vacuum heat insulation panel over time due to water vapor and gas, in the same manner as the core material with the binder, a glass short fiber is previously used. It is preferable to age the material at 180 ° C. or higher.

  Although two examples were given for the form of the core material, the core material was sealed by being inserted into the jacket material 4 to reduce the pressure inside the jacket material 4 and heat-sealing the peripheral edge of the jacket material 4. Any material can be used as long as the shape can be maintained after production, and known materials can be used.

  The short glass fiber material preferably has an average fiber diameter of 2 to 4 μm. The short glass fiber material greatly affects the thermal conductivity characteristics and cost depending on the average fiber diameter. Glass wool having an average fiber diameter of 5 μm or more, which has been used as the mainstream of glass fibers, is a material that is easy to put into practical use because it is inexpensive in terms of cost, but its thermal conductivity and deterioration over time are greatly inferior. The reason for this is that the fibers are arranged in the same direction and the contact of the fibers is close to the line, and the fibers are double-bonded with a binder, the contact thermal resistance is reduced, the thermal conductivity is increased, and the deterioration with time progresses rapidly. It is done. On the other hand, if the average fiber diameter is less than 2 μm, the thickness per sheet is thin and the heat insulation performance is poor. Therefore, by increasing the thickness by stacking sheet-like inorganic fiber aggregates, it is possible to reduce thermal conductivity and deterioration with time. However, increasing the thickness by stacking sheet-like inorganic fiber aggregates increases the number of sheets used for the core material, resulting in inferior productivity and increased cost. It was also found that when the vacuum heat insulating panel was produced with an average fiber diameter of less than 2 μm, the thickness reduction rate of the core material increased before and after sealing.

  As described above, since the thermal conductivity is increased when the fiber diameter is 5 μm or more, a fiber material that is discontinuous in the heat transfer direction and that effectively uses the contact resistance between the materials is selected. In addition to the contact thermal resistance, the heat flow path becomes zigzag, and a short glass fiber material having an average fiber diameter of 3 to 5 μm is selected from many fiber materials whose thermal resistance increases and thermal conductivity decreases. Therefore, it is possible to achieve both reduction in thermal conductivity and deterioration with time, reduction in thickness reduction rate, and cost reduction.

  In addition, about the fiber direction of a short glass fiber material, what is arranged along with a horizontal direction with respect to the thickness direction of a vacuum heat insulation panel is preferable at the point of heat insulation performance.

  Regarding the film configuration on one side of the jacket material 4, as the configuration A, a polyethylene terephthalate film (12 μm) on which aluminum was deposited as a surface protective layer from the outer layer, an aluminum foil (6 μm) as a gas barrier layer, and a high heat sealing layer A density polyethylene film (50 μm), and a laminate film using a polyamide film (15 μm) as a surface protective layer as an outermost layer for improving scratch resistance. Also, as composition B, aluminum is used as a surface protective layer and gas barrier layer from the outer layer. Vapor-deposited polyethylene terephthalate film (12 μm), aluminum-deposited ethylene-vinyl alcohol copolymer resin (trade name EVAL, manufactured by Kuraray Co., Ltd.) (12 μm), high-density polyethylene film (50 μm) as a thermal fusion layer, To further improve scratch resistance Polyamide film (15 [mu] m) laminate film can be used used as a surface protective layer in the outermost layer. As the configuration of the jacket material 4, the combination of the above-described configuration A + configuration A (double-sided foil jacket material), configuration A + configuration B (foil + vapor deposition jacket material), configuration B + configuration B (double-sided vapor deposition jacket material) In the film of these configurations, it is used as a bag in which the heat-sealing layers are bonded to each other at the end faces.

  This is because the outermost layer of the outer cover material 4 is for the purpose of responding to impacts, the intermediate layer is for ensuring gas barrier properties, and the innermost layer is for sealing by thermal fusion. Therefore, all known materials can be used as long as they meet these purposes. Further, as a means for further improvement, two films having an aluminum vapor deposition layer as an intermediate layer may be provided. As the innermost layer to be heat-sealed, polypropylene resin or polyacrylonitrile resin may be used.

  The adsorbing member 3 is a synthetic zeolite that adsorbs water vapor and organic gas, water vapor released from the core material 2, water vapor and air entering from the outside through the outer covering material 4, and organic gas generated from the outer covering material 4. It is preferable to absorb the odor and suppress the deterioration of the vacuum heat insulating panel 11 with time. Further, the shape of the synthetic zeolite is not particularly limited, such as powder, fine particles, granules, tablets, solids and the like.

  Further, in this embodiment, synthetic zeolite is used as the adsorbing member 3, but in order to improve the reliability of the vacuum heat insulating panel 11, quick lime, dawsonite, hydrotalcite, metal hydroxide as necessary. It is also effective to use a gas adsorbent such as barium or an alloy such as barium-lithium alloy.

  The adsorbing member 3 is inserted into the fiber layer of the core material 2 when the vacuum heat insulating panel 11 is manufactured. By this insertion, an external force equivalent to atmospheric pressure is applied to the jacket material 4 after manufacturing the vacuum heat insulating panel 11, but the jacket material 4 is not damaged or broken by the particles of the adsorption member 3, and vacuum is applied. The reliability with respect to the heat insulation performance of the heat insulation panel 11 is not impaired.

  The convex flat portion 15 disposed on the vacuum heat insulating panel 11 is placed on the outer cover material 4 by placing a flat thin plate 17 on the core material 2, and the inner pressure of the outer cover material 4 is reduced. It can be produced by sealing the peripheral edge of the film by heat sealing. As the material of the flat thin plate 17, all known materials such as a metal plate and a glass plate can be used. However, in order to avoid misjudgment due to a heat bridge when measuring the thermal conductivity, a material having a relatively low thermal conductivity is used. In particular, a glass short fiber material, which is the same material as the core material 2, is most preferably baked and hardened using a binder or the like.

  Further, a concave flat portion 16 can be disposed on the vacuum heat insulating panel 11 instead of the convex flat portion 15. When the concave flat portion 16 is provided, the core material 2 is inserted into the jacket material 4 without placing anything on the core material 2, the inside of the jacket material 4 is decompressed, and the periphery of the jacket material 4 After the parts are heat-sealed and sealed, pressure can be applied from the outside of the vacuum heat insulation panel 11 to perform post-processing.

  At the time of measuring thermal conductivity, the size of the heat generating device 22 that is a contact portion of the thermal conductivity measuring device 21 with the object to be measured is 50 mm in diameter, so that the convex shape disposed on the vacuum heat insulating panel 11. The size of the flat portion 15 must be a size that can include a circle having a diameter of 50 mm. Further, when the thermal conductivity measuring device 21 is arranged on the convex flat portion 15 of the vacuum heat insulating panel 11, the convex / concave portion of the convex flat portion 15 is zero, and the heat generating device 22 of the thermal conductivity measuring device 21 is convex. Most preferably, the gap with the shaped flat portion 15 is completely zero. However, even if the convex flat portion 15 has an unevenness of 0.1 mm corresponding to the thickness of the jacket material 4, the gap between the heat generating device 22 of the thermal conductivity measuring device 21 and the convex flat portion 15 is zero. It can be said that the unevenness of the convex flat portion 15 is preferably within 0.1 mm. Since the thickness of the vacuum heat insulation panel 11 is about 10 mm, the height of the convex flat portion 15 has little influence on the thermal conductivity performance of the entire vacuum heat insulation panel 11 and is 10 minutes of the thickness of the vacuum heat insulation panel 11. It is preferably 1 mm or less, which is 1 or less.

For example, in the vacuum heat insulating panel 11 in which the convex flat portion 15 has a circular shape with a diameter of 60 mm, a height of 1 mm, and a thermal conductivity of 2.5 mW / m · K, By arranging the thermal conductivity measurement device 21 and conducting the thermal conductivity measurement inspection, as shown in Table 1, the output voltage from the thermal conductivity measurement device 21 is higher than the threshold voltage, so it is determined to be OK. As a result, it is possible to provide a vacuum thermal insulation panel that can maintain excellent thermal insulation performance over a long period of time.
[Example 2]
Various members constituting the vacuum heat insulation panel are all the same as those described in [Example 1]. In the vacuum heat insulating panel 11 in which the concave flat portion 16 has a circular shape with a diameter of 50 mm and a height of 0.5 mm, a thermal conductivity measuring device 21 is disposed on the concave flat portion 16 to thereby increase the thermal conductivity. By performing the measurement inspection, as shown in Table 1, the output voltage from the thermal conductivity measuring device 21 is determined to be OK because it is higher than the threshold voltage, and as a result, a vacuum that can maintain excellent heat insulation performance over a long period of time. Insulation panels can be provided.
[Comparative Example 1]
About the various members which comprise a vacuum heat insulation panel, except the thing regarding a convex-shaped flat part, it is the same as that of the thing as described in [Example 1]. In the vacuum heat insulation panel 1 in which the convex flat portion is not disposed, the depth of the concave portion on the surface of the core material 2 is 0.2 mm. By arranging the heat generating device 22 of the thermal conductivity measuring device 21 in this concave shape portion and conducting the thermal conductivity measurement inspection, as shown in Table 1, the output voltage by the thermal conductivity measuring device 21 is higher than the threshold voltage. Therefore, it is determined as NG, and a highly accurate result cannot be obtained. As a result, a vacuum heat insulating panel with high performance reliability cannot be provided.
[Comparative Example 2]
About the various members which comprise a vacuum heat insulation panel, except the thing regarding a convex-shaped flat part, it is the same as that of the thing as described in [Example 1]. In the vacuum heat insulation panel 1 in which the convex flat portion 5 has a circular shape with a diameter of 40 mm and a height of 1 mm, a thermal conductivity measuring device 21 is arranged on the convex flat portion 5 to conduct a thermal conductivity measurement inspection. As shown in Table 1, the output voltage from the thermal conductivity measuring device 21 is lower than the threshold voltage, so that a gap is generated between the heat generating device 22 and the convex flat portion. As a result, it is impossible to provide a vacuum heat insulation panel with high performance and reliability.

  Needless to say, if the size of the heat generator 22 is 40 mm or less, the size of the flat portion may be 40 mm.

  The specification of the vacuum heat insulation panel used by the Example and the comparative example, and the result of a heat conductivity measurement test are shown.

It is sectional drawing of the vacuum heat insulation panel of this invention and Example 1. FIG. It is sectional drawing of the vacuum heat insulation panel of this invention and Example 2. FIG. It is sectional drawing of the vacuum heat insulation panel shown by the prior art or the comparative example 1. FIG. It is sectional drawing of the vacuum heat insulation panel shown by the comparative example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vacuum insulation panel shown by the prior art or a comparative example, 2 ... Core material, 3 ... Adsorption member, 4 ... Cover material, 5 ... Convex flat part shown by the comparative example 2, 11 ... Vacuum insulation panel of this invention , 15 ... convex flat part shown in the present invention / Example 1, 16 ... concave flat part shown in the present invention / Example 2, 17 ... flat thin plate, 21 ... thermal conductivity measuring device, 22 ... heat Generator.

Claims (6)

  A vacuum heat insulation panel comprising a core material, an adsorbing member for adsorbing water vapor and organic gas, and an outer packaging material made of a gas barrier film, wherein a flat portion is disposed on the vacuum heat insulation panel. .   The vacuum heat insulation panel according to claim 1, wherein the flat portion disposed on the vacuum heat insulation panel is convex with respect to a portion other than the flat portion.   The vacuum insulation panel according to claim 1, wherein the flat part disposed on the vacuum insulation panel is concave with respect to a part other than the flat part.   The vacuum heat insulating panel according to claim 2 or 3, wherein the flat portion disposed on the vacuum heat insulating panel can include a circle having a diameter of 50 mm.   The vacuum heat insulation panel according to claim 4, wherein the unevenness of the flat portion disposed on the vacuum heat insulation panel is within 0.1 mm. Heat is generated between the object to be measured and the heat resistance material, and heat is passed through the object to be measured and the heat resistance material, and the thermal conductivity of the object to be measured is obtained from the temperature difference between at least two locations of the heat resistance material. In the thermal conductivity measuring method, the vacuum heat insulation panel according to any one of claims 1 to 5 is used as an object to be measured, and a thermal conductivity measurement device is disposed on a flat portion of the vacuum heat insulation panel for measurement. A method of measuring thermal conductivity.

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