JP2020112181A - Vacuum heat insulating material and its manufacturing method - Google Patents

Abstract

To provide a vacuum heat insulating material with high heat insulating performance and excellent dimension accuracy, which uses glass fiber fabricated by a continuous filament method or the like.SOLUTION: A vacuum heat insulating material has a core material formed by stacking less than 40 pieces of glass long fiber mats each having a thickness of 0.5 mm or more before evacuation.SELECTED DRAWING: Figure 6

Description

The present invention relates to a vacuum heat insulating material and a manufacturing method thereof.

A vacuum heat insulating material including a core material containing glass fiber or the like as a main component is known. Glass fibers can be classified into continuous fibers manufactured by the continuous filament method or chopped strand method and short fibers manufactured by the centrifugal method or burner method, but there is an active movement to adopt long fibers from the viewpoint of safety. Is becoming.

When long fibers are used, it becomes easier to form a thin web (mat) than so-called short fibers even during so-called dry production. When the core material is formed using the web, the number of overlapping sheets can be increased, so that so-called longitudinal fibers extending in the thickness direction can be suppressed.

Patent Document 1 discloses a vacuum heat insulating material that uses a core material in which 40 or more webs that are not needle punched are stacked on glass fibers manufactured by a continuous filament method. Further, after forming the web, the bundling material is removed by heating at 300° C. to 750° C. (0022).

Patent Document 2 discloses a vacuum heat insulating material in which at least 6 or more needle mats obtained by needle punching glass fibers manufactured by a continuous filament method are laminated (0016).

JP, 2005-137689, A JP, 2005-137688, A

Both Patent Documents 1 and 2 attempt to increase the number of overlapping sheets. However, if the number of overlapped sheets increases, positional deviation easily occurs during stacking, compression thermoforming, and vacuuming.

In Patent Document 1, the web is heated, but as a result of studies by the present inventors, it is necessary to pay attention to the thickness of the web when heating, and specifically, as described later, when a thin web is heated. A problem has been found that heat welding occurs.

In Patent Document 1, since the glass fiber manufactured by the continuous filament method is used as a core material without using needle punching and does not contain a binder, the core material is soft and difficult to handle. Therefore, as the number of laminated layers increases, layer displacement and shrinkage occur when the core material is inserted into the jacket material, and there is a problem in dimensional accuracy when the vacuum heat insulating material is used.

Patent Document 2 states that it becomes difficult for the longitudinal fibers to be continuous by laminating six or more sheets (0014). However, it is said that when the number of laminated needle mats increases, stacking deviation tends to occur, but when the number of laminated needles decreases, the performance deteriorates sharply.

The first present invention made in view of the above circumstances,
It is a vacuum heat insulating material having a core material formed by stacking less than 40 mats of long glass fibers each having a thickness of 0.5 mm or more before evacuation.

The second invention made in view of the above circumstances,
It is a vacuum heat insulating material having a core material in which 5 or less layers of needle mats obtained by needle punching a plurality of long glass fiber mats are laminated.

Front view of the refrigerator in the embodiment The longitudinal cross-sectional view of the refrigerator in the embodiment (A-A cross section of FIG. 1) FIG. 2 is a view of the refrigerator in the embodiment as viewed from the inside of the refrigerator (viewed from the arrow BB in FIG. 2). Explanatory drawing of the vacuum heat insulating material in embodiment Sectional drawing of the vacuum heat insulating material of Example 1 of this invention. Sectional drawing of the vacuum heat insulating material of Example 2 of this invention

A refrigerator including a vacuum heat insulating material according to an embodiment of the present invention will be described in detail below with reference to the drawings.

(Embodiment)
FIG. 1 is a front view showing the appearance of a refrigerator provided with a vacuum heat insulating material according to an embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of the refrigerator including the vacuum heat insulating material according to the embodiment, and is a cross-sectional view taken along line AA of FIG. 1. FIG. 3 is a BB perspective view of the refrigerator including the vacuum heat insulating material according to the first embodiment.

The refrigerator 1 has a refrigerating compartment 2, an ice storage compartment 3a, an upper freezing compartment 3b, a freezing compartment 4 and a vegetable compartment 5 from the top. Except for the refrigerator compartment doors 6a and 6b and the refrigerator compartment doors 6a and 6b which rotate around the hinge 10 and the like, all are drawer type doors, and the ice storage compartment door 7a, the upper stage freezer compartment door 7b, the lower stage freezer compartment door 8 and the vegetables. The room door 9 is arranged.

Further, a partitioning heat wall 12 is arranged to partition and insulate the refrigerating compartment 2 from the ice making compartment 3a and the upper freezing compartment 3b. The partitioning hot wall 12 is a heat insulating wall having a thickness of about 30 to 50 mm, and is made of styrofoam, foamed heat insulating material (urethane foam), vacuum heat insulating material, etc., either alone or in combination of a plurality of heat insulating materials.

The box body 20 includes an outer box 21 and an inner box 22, and a heat insulating portion is provided in a space formed by the outer box 21 and the inner box 22 to insulate the storage chambers inside the box body 20 from the outside. There is. A vacuum heat insulating material 150 is arranged on either the outer box 21 side or the inner box 22 side, and a space other than the vacuum heat insulating material 150 is filled with a foam heat insulating material 23 such as hard urethane foam. The vacuum heat insulating material 150 will be described later.

In this embodiment, the vacuum heat insulating material 150 is arranged on the back surface of the recess 40 to ensure heat insulating performance. In the first embodiment, the vacuum heat insulating material 150 is one vacuum heat insulating material 150 formed in a substantially Z shape so as to straddle the case 45a of the interior lamp 45 and the electric component 41.

Further, since the compressor 30 and the condenser 31 arranged in the lower rear portion of the box body 20 are parts that generate a large amount of heat, in order to prevent heat from entering the inside of the box, vacuum projection is performed on the projection surface toward the inner box 22 side. The material 150 is arranged.

Further, the vacuum heat insulating material 150 is also arranged on the outer surface (on the heat insulating material 23 side) of the inner box 22 at the bottom surface of the vegetable compartment 5. As described above, the ceiling is provided with the vacuum heat insulating material 150, and the both sides are provided with the vacuum heat insulating material 150 on the inner surface of the outer box 23 so as to extend over the refrigerating compartment 2, the freezing compartments 3a, 3b, 4 and the vegetable compartment 5. As for the chamber doors 6a and 6b, the freezing chamber door 8 and the vegetable chamber door 9, the vacuum heat insulating material 150 is arranged on the inner surface of the outer box 22 (glass plate in this embodiment). In addition, a vacuum heat insulating material 150 is also arranged on each of the partition heat insulating layers 12 and 14. The arrangement and number of the vacuum heat insulating materials 150 are not particularly limited.

Next, the vacuum heat insulating material will be described. FIG. 4 shows an example of the vacuum heat insulating material 50. A core material 51, an inner packaging material 52 for temporarily retaining the core material 51 in a compressed state, and a core material retained in a compressed state by the inner packaging material 52. It is composed of an outer covering material 53 having a gas barrier layer covering 51 and an adsorbent 54. The outer covering material 53 is arranged on both surfaces of the vacuum heat insulating material 50, and is formed into a bag shape in which laminated films of the same size are faced to each other and a certain width portion is heat-welded from the end portion of each side.

Regarding the core material 51, the use of a laminate of inorganic fiber materials reduces outgas, which is advantageous in terms of heat insulation performance, but is not particularly limited to this. Binder-molded ones, inorganic fibers such as ceramic fibers, rock wool, glass fibers other than glass wool, and organic fibers may be used, and there is no particular limitation. The inner packaging material 52 may not be used depending on the type of the core material 51.

The laminate structure of the outer covering material 53 is not particularly limited as long as it has gas barrier properties and can be heat-welded, but four layers of a surface layer, a first gas barrier layer, a second gas barrier layer, and a heat-welding layer. The laminated film consisting of the composition, the surface layer is a resin film having low hygroscopicity, the first gas barrier layer is a resin film provided with a metal vapor deposition layer, and the second gas barrier layer is a resin film having a high oxygen barrier property and a metal vapor deposition layer. The first and second gas barrier layers are provided so that the metal vapor deposition layers face each other. As for the heat-welding layer, a film having a low hygroscopic property was used similarly to the surface layer. Specifically, the surface layer is biaxially oriented polypropylene, the first gas barrier layer is a polyethylene terephthalate with aluminum vapor deposition, the second gas barrier layer is a biaxially oriented ethylene vinyl alcohol copolymer resin film with aluminum vapor deposition, The welding layer was a linear low-density polyethylene film. The jacket material 53 is not particularly limited to this configuration. The surface layer may be polyamide (nylon), polyethylene terephthalate or the like, and the first and second gas barrier layers may be those in which a metal foil or a resin film is provided with a gas barrier film such as an inorganic layered compound or a resin gas barrier coating material. .. For the heat-welding layer, for example, a polybutylene terephthalate film having a high oxygen barrier property, a highly versatile polypropylene film, or a polyethylene film having a high density, a medium density, a low density or the like may be used. Further, the film configuration may be different between the outer box side and the inner box side of the vacuum heat insulating material 50. For example, the second gas barrier layer may be a combination of an aluminum vapor-deposited film on one surface and an aluminum foil on the other surface without any problem. Although each layer is bonded by a dry lamination method via a two-component curing type urethane adhesive, the adhesive and the bonding method are not particularly limited thereto.

The purpose of disposing a resin having low hygroscopicity in the surface layer and the heat-welding layer is that the gas barrier layer film having a high oxygen barrier property deteriorates in gas barrier property due to moisture absorption. The amount of moisture absorption of the entire film is suppressed. As a result, even in the vacuum evacuation process of the vacuum heat insulating material 50, the amount of water brought into the jacket material 53 is small, so that the vacuum evacuation efficiency is significantly improved, leading to higher performance.

Although the heat-weldable polyethylene film is used for the encapsulating material 52 and the physical adsorption type synthetic zeolite is used for the adsorbent 54, the materials are not limited to these materials. The inner packaging material 52 may be a polypropylene film, a polyethylene terephthalate film, a polybutylene terephthalate film or the like as long as it has low hygroscopicity and can be heat-welded and has a small outgas, and the adsorbent 54 adsorbs water (water or water vapor). Therefore, either physical adsorption or chemical reaction type adsorption may be used.

(Example 1)
In the vacuum heat insulating material 150 of Example 1 shown in FIG. 5, long fibers obtained by a continuous filament method or a chopped strand method are used as glass fibers serving as a core material. The glass fiber produced by a known long fiber production method is cut using, for example, about 50 mm while being bundled using a sizing agent. As the sizing agent, for example, any one or more of urethane resin, vinyl acetate resin, acrylic resin, epoxy resin, polyether polymer, surfactant, coupling agent, lubricant, antistatic agent and the like are included. The one used is.

Next, the cut glass fibers are opened and molded into a mat. In this embodiment, a mat (web) in which long fibers having an average fiber diameter of 7 to 9 μm are thinly bundled is prepared.

After stacking multiple mats, perform needle punching and combine them into a needle mat. This makes it possible to reduce the bulk of the core material while increasing the number of mats. Therefore, it is possible to reduce the necessity of using the inner packaging material 52 and facilitate insertion into the outer covering material 53. At this time, the thickness of each mat is not particularly limited, but the thickness of the needle mat 1 layer before evacuation is 1 mm or more from the viewpoint of suppressing displacement during evacuation or when cutting the core material to a specified dimension, It is preferably 3 mm or more. However, the thicker the core material, the higher the needle resistance during needle punching, and the more difficult it becomes to process, so the thickness is preferably 30 mm or less. Further, as the thickness of the core material 1 layer is thicker, the fibers are oriented in the heat insulating direction by the needle punching process and the solid heat conduction by the fibers is increased. Therefore, the thickness of the core material 1 layer is preferably small.

Further, in order to reduce the stacking deviation, it is preferable that the number of stacked needle mats 51 is 5 or less. In the core material of this embodiment, one layer of a needle mat having a width of 600 mm and a length of 600 mm has a thickness of 5 mm and the number of laminated layers of the needle mat 51 is 5 layers. When the vacuum heat insulating material was produced by vacuuming, the thickness was 18 mm, and the dimensional deviation when using the vacuum heat insulating material could be 3 mm or less.

Further, by subjecting the core material to compression thermoforming at 550° C. to 750° C., the strain of the long fibers can be removed, and the sizing agent can be volatilized. Since needle punching is performed, the need for a binder can be reduced, and even if used, it will volatilize by compression thermoforming.

(Example 2)
When needle punching is performed, mats that are soft and relatively difficult to handle can be put together, but continuous fibers are generated in the longitudinal direction (thickness direction), so it is preferable to form the core without needle punching. ..

The vacuum heat insulating material 250 of the second embodiment shown in FIG. 6 uses the same long fibers as in the first embodiment. In this embodiment, the mat 510 has a thickness of 0.5 mm or more, and a plurality of the mats 510 (which will be described later, but less than 40) are stacked and compression-thermoformed to form a core material.

In order to suppress so-called longitudinal fibers extending in the laminating direction of the fibers, it is preferable that the number of mats is large when the amount of glass fibers is the same, but as a result of examination, the performance is rather rather increased simply by increasing the number of mats. It turned out to fall. Upon investigating the cause, it was found that when a thin mat was mixed, the fibers were fused together during compression thermoforming.

Specifically, when compression thermoforming is performed on a mat having a thickness of less than 0.5 mm that is not needle punched, heat during the compression thermoforming is easily transferred, and the mat is softened with a small amount of heat, so that it can be widely used in fibers. Was found to melt easily.

On the other hand, it was found that when the number of overlapping mats is 40 or more, the stacking deviation and the positional deviation during heating and compression become remarkable.

Here, the management of the mat is based on the basis weight (mass of glass fiber per unit area), but the management based on the basis weight tends to cause large variations among the mats. Further, the weight per unit area controls the mass (glass fiber density) of the mat as defined, but does not control the thickness. The present inventors have found that when a thin mat is mixed, a welded portion and an unwelded portion are likely to occur even if the temperature during compression thermoforming is lowered or the drying time is shortened. Since the solid heat conduction of the core material increases as the size of the welded portion increases, the performance of the vacuum heat insulating material deteriorates.

Therefore, in this example, less than 40 mats 510 each having a thickness of 0.5 mm or more were stacked to form a core material. By doing so, even if the laminated mat (core material) was compression-thermoformed and dried at 550°C to 750°C to volatilize the sizing agent for the long fibers, the occurrence of thermal welding could be suppressed.

In this embodiment, one mat having a width of 600 mm and a length of 600 mm has a thickness of 0.7 mm, and 39 mats are laminated. When the vacuum heat insulating material was produced, the thickness became 18 mm. The dimensional deviation of the vacuum heat insulating material could be 2 mm or less.

It should be noted that the vacuum heat insulating material can be expected to be used in a product field requiring heat insulation such as a refrigerator, a vending machine, and a water heater.

1 refrigerator, 2 refrigerating room, 3a ice storage room, 3b upper freezing room,
4 Lower Freezer, 5 Vegetable Room, 6a Refrigerator Door, 6b Refrigerator Door,
7a ice storage compartment door, 7b upper freezing compartment door, 8 lower freezing compartment door,
9 vegetable compartment door, 10 door hinge, 11 packing,
12, 14 Adiabatic partition, 13 Partition member,
20 box, 21 outer box, 22 inner box, 23 foam insulation,
27 blower, 28 cooler, 30 compressor, 31 condenser,
33 expanded polystyrene, 40 recesses, 41 electrical parts,
42 cover, 45 interior light, 45a case,
50 vacuum insulation,
51 needle mat,
510 mat,
52 inner bag,
53 outer covering,
150,250 Vacuum insulation.

Claims (5)

A vacuum heat insulating material having a core material formed by stacking less than 40 mats of long glass fibers each having a thickness of 0.5 mm or more before evacuation. It is a manufacturing method of the vacuum heat insulating material of Claim 1, Comprising:
The said core material was heat-compressed at 550 degreeC-750 degreeC, The manufacturing method characterized by the above-mentioned. A vacuum heat insulating material having a core material in which 5 or less needle mats obtained by needle-punching a plurality of glass long fiber mats are laminated. The vacuum heat insulating material according to claim 3, wherein each of the needle mats has a thickness of 1 mm or more before being vacuumed. It is a manufacturing method of the vacuum heat insulating material of Claim 3 or 4, Comprising:
A manufacturing method, wherein the core material is heated and compressed at 550°C to 750°C.

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