JP2003269689A - Vacuum insulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum insulator which contains no impurities causing outgassing, has connectability, is excellent in handleability and heat resistance, easy to transport, excellent in heat insulation performance, and easy to fold. <P>SOLUTION: The vacuum insulator is formed by mixing glass wool with a thermoplastic resin fiber to form a mixture in the form of a flat plate, welding and bonding together intersections where the resin fiber of the mixture contacts other fibers to compress the mixture, providing the flat plate-shaped mixture with a linear thin-walled part to form a core for the vacuum insulator, housing the core in a container, evacuating the interior of the container, and sealing the container. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vacuum heat insulating material and a heat insulating box using the vacuum heat insulating material.

[0002]

2. Description of the Related Art Conventionally, as a heat insulating material used for various heat retaining / heating / cooling devices such as freezers, refrigerators for home use, heat retention machines, and showcases for commercial use, and heat insulation materials for cold storage vehicles, cold storage warehouses, etc. Insulation is used.

In addition, some of these various heat retaining / heating / cooling devices employ a vacuum heat insulating material in order to further improve the heat insulating performance.

In this vacuum heat insulating material, a continuous foam material, powder, or fiber is stored in a container in which a gas barrier film is formed in a bag shape, and in this storage state, air is exhausted from the inside of the container and hermetically sealed. The inside is kept in a vacuum state.

As described above, the core material of the vacuum heat insulating material is an open-cell urethane (communicating urethane) obtained by foaming hard urethane to make the cells communicate with each other, or a styrofoam foam made by extrusion molding to make the cells communicate with each other. It is also used that the product is cut into a required size, placed in a container having a gas barrier property together with an adsorbent, evacuated from the inside, hermetically sealed, and kept in a vacuum state.

However, since the urethane production method is a curing reaction of two liquids, there is a problem that outgas derived from unreacted substances remaining during the reaction is generated after sealing and deteriorates the heat insulating performance of the vacuum heat insulating material.

Further, such as the open-cell foam polystyrene
In organic foam, 100% of the cells are completely connected.
It is difficult to form a spilled material and some closed cells remain.
CO generated from a blowing agent such as isobutane²
Remains in the closed bubbles. That
As a result, open-cell foam polystyrene has gas barrier properties
Even if placed in a container and hermetically sealed after exhausting from the inside,
CO remaining in the bubbles ²Due to outgas caused by
Therefore, the heat insulation performance of the vacuum insulation material gradually decreases.
There is also a subject.

In order to solve this problem, an adsorbent (getter) is enclosed together with the core material in the container used for the vacuum heat insulating material, and the generated gas is adsorbed to prevent deterioration of the heat insulating performance. However, even when the adsorbent is enclosed, it is difficult to completely prevent the deterioration of the heat insulating performance due to the outgas.

As a material replacing the above-mentioned pearlite powder, open cell urethane, open cell styrofoam, etc., there has been proposed a material using non-alkali long fiber glass wool as a core material for a vacuum heat insulating material.

The alkali-free long-fiber glass wool has the advantages that it has a very high heat-insulating performance, has continuity, does not require outgassing, does not require an adsorbent, and does not require a foaming agent.

On the other hand, since glass wool has a low bulk specific gravity (density) (about 20 kg / m ³ ), when only glass wool is used as the core material for the vacuum heat insulating material, it is put in a vacuum heat insulating material container and vacuumed. Density after pulling is 400
Since it is more than kg / m ³ and is compressed 10 times or more, inconvenience occurs in handling (handling) and transportation surface (delivery) during manufacturing, pressure resistance against atmospheric pressure is low, and deformation is likely to occur. There are problems such as the need for a vacuum heat insulating material container.

In order to solve the above problems, Japanese Patent Laid-Open No. 7-96
In Japanese Patent No. 563, a vacuum heat insulation in which the density of the core material for a vacuum heat insulating material is increased in advance by subjecting a pile of glass wool to a needle punching process and the volume shrinkage after being housed in a container and evacuated is suppressed to be small Wood is proposed.

In this vacuum heat insulating material, the needle punching process enables the glass wool to be entangled with each other and hardened, whereby the density of the core material can be increased in advance, and further, the glass wool is hardened with an organic binder or the like. It is excellent in that there is no need to worry about outgas generated from the organic binder, since the treatment of No. 1 is unnecessary.

However, since only glass wool is used as the material of the core material, there is a problem in that it is difficult to put it into practical use in terms of cost.

Therefore, in Japanese Patent Application Laid-Open No. 9-136367, there is provided a cost-effective vacuum heat insulating material in which glass wool is mixed with an inexpensive fibrous material such as pulp or rock wool as a core material. Has been proposed,
At present, no one has been found that has the same heat insulating performance as that of the vacuum heat insulating material using only glass wool.

An example of the vacuum heat insulating material will be described.

The vacuum heat insulating material is provided with at least a core material for vacuum heat insulating material and a container for accommodating the core material for vacuum heat insulating material and capable of maintaining a vacuum inside.

FIG. 1 is an example of a sectional view of a main part of a vacuum heat insulating material. The core material 10 for a vacuum heat insulating material is cut into an appropriate size and shape (for example, a quadrangle), and dried to remove water contained therein.

Next, the cut and dried core material 10 for a vacuum heat insulating material is placed in a container 18 which constitutes one surface of a container for accommodating the core material and capable of maintaining a vacuum inside,
Further, after covering the container 18 constituting the other surface of the container, the three sides are heat-sealed.

This is placed in a vacuum chamber (not shown) and evacuated, and the degree of vacuum in the container 18 is set to 13.3 Pa to 1.3.
The vacuum heat insulating material 16 is formed by setting the pressure to 3 Pa (0.1 to 0.01 Torr) and heat-sealing the remaining one side.

The container 18 has a gas barrier property,
Any material can be used as long as it can be heat-sealed and the inside of the core material can be housed to maintain a vacuum, for example, nylon or aluminum vapor-deposited PET.
A container using a gas barrier film having a four-layer structure of (polyethylene terephthalate), aluminum foil, and high density polyethylene is preferably used.

By only placing the core material 10 in the container 18, a vacuum heat insulating material 16 having heat insulating performance and less deterioration in heat insulating performance can be obtained, but deterioration of heat insulating performance due to a slight amount of outgas is prevented. In order to do so, it is also preferable to further encapsulate an adsorbent.

Next, an example of using the vacuum heat insulating material as the heat insulating material of the refrigerator will be described with reference to FIG. Figure 2
FIG. 4 is a sectional view of a main part of a refrigerator using a vacuum heat insulating material.

In FIG. 2, the refrigerator 21 includes an outer box 22.
A heat insulating section 23 arranged inside the outer box 22, an inner box 24 arranged inside the heat insulating section 23, and a heat insulating door 25 that opens and closes the opening of the inner box 24. .

The heat insulating section 23 comprises a vacuum heat insulating material 26 and a foam heat insulating material 27. The vacuum heat insulating material 26 is attached in contact with the inner wall of the outer box 22, and the polyurethane foam 27 is filled and foamed between the outer box 22 and the inner box 24 to form the heat insulating section 23.
Is formed. The heat insulating part 23 can be made thin by using the vacuum heat insulating material 26 having a low heat conductivity (high heat insulating performance) so that the heat conductivity can be kept low. Become.

By the way, since the vacuum heat insulating material is generally flat, the vacuum heat insulating material cannot be arranged at the corners.

Therefore, a bendable vacuum heat insulating material has been proposed in order to improve the heat insulating performance at this corner portion. This foldable vacuum heat insulating material has been proposed, for example, in Japanese Utility Model Publication No. 63-26705 (F25D23 / 06) and Japanese Patent Application Laid-Open No. 7-96566 (B32B3 / 12). However, since it can be bent, the structure is complicated and the manufacturing becomes difficult.

[0028]

DISCLOSURE OF THE INVENTION The present invention does not contain impurities such as unreacted substances, foaming agents, and organic binders that cause outgas, has continuity, and has excellent vacuum insulation properties. The purpose is to provide wood.

Another object of the present invention is to provide a vacuum heat insulating material which is bendable and easy to manufacture and handle.

[0030]

According to the present invention, a mixture (34, 38, 40) containing glass wool (31) and thermoplastic resin fibers (32) is heated at a temperature higher than the melting point of the thermoplastic resin fibers. Core material for a vacuum heat insulating material by performing shape retention at a temperature lower than the melting point temperature after the pressure compression so that the shape after the pressure compression is maintained after the pressure is compressed. 47, 49, 55, 56), and the formed core material for vacuum heat insulating material in a container (18)
The vacuum heat insulating material (58) is characterized in that the vacuum heat insulating material (58) is housed in a container, and the inside of the container (18) is evacuated and then the container is sealed.

Furthermore, the present invention is characterized in that the thermoplastic resin fiber (32) is polypropylene.

Further, according to the present invention, a mixture containing glass wool and thermoplastic resin fibers is heated at a temperature higher than the melting point of the thermoplastic resin fibers, and after this heating, pressure compression is applied to obtain a flat mixture ( 47) is formed, and the thickness is maintained at a temperature lower than the melting point temperature after the compression so as to maintain the thickness after the compression.
9, 55, 56), and the formed vacuum insulation core material (49, 55, 56) is housed in a container (18),
The vacuum heat insulating material is characterized in that the inside of the container is evacuated and then the container is sealed.

Furthermore, the present invention is characterized in that when the flat plate mixture is maintained at the low temperature, the linear recesses (54, 54) are formed in the flat plate mixture.

According to the present invention, the glass wool and the thermoplastic resin fibers are mixed to form a flat mixture, and the thermoplastic resin fibers of the mixture are melted and bonded at the intersections of the other fibers. While compressing this mixture, linear recesses (54, 54) are formed in this flat mixture.
To form the core material (55, 56) for the vacuum heat insulating material,
The vacuum heat insulating material (58) is characterized in that the formed core material for vacuum heat insulating material is housed in a container (18), the inside of the container is evacuated, and then the container is sealed.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION The vacuum heat insulating material of the present invention will be described in detail.

The vacuum heat insulating material of the present invention comprises at least the core material for vacuum heat insulating material of the present invention, and a container for accommodating the core material for vacuum heat insulating material and capable of maintaining a vacuum inside.

First, the vacuum heat insulating core material will be described.

The core material for vacuum heat insulating material contains glass wool and thermoplastic resin fibers (for example, polypropylene fibers).

As a material of the core material for the vacuum heat insulating material, not only glass wool but also the thermoplastic resin fiber is mixed into the core material so that the cost can be kept low and the heat insulating performance is almost the same as that of the glass wool alone. Is preferable, and the amount of outgas generated is small, which is preferable.

In addition, the thermoplastic resin fiber, while maintaining the continuity of the glass wool and the thermoplastic resin fiber,
It is preferably bonded to the glass wool by heating, melting and pressing.

That is, by heating, melting and pressing a mixture of glass wool and thermoplastic resin fibers, the contact portion between the glass wool and the thermoplastic resin fibers adheres to increase the pressure resistance, and the density is increased in advance. Since the height can be increased, it is possible to suppress deformation and volume shrinkage during evacuation. That is, the thermoplastic resin fiber also functions as a binder.

A preferred embodiment of the method for manufacturing the vacuum heat insulating core material will be described.

The core material for the vacuum heat insulating material is a step of mixing and defibrating glass wool and thermoplastic resin fibers to obtain a cotton-like mixture (hereinafter referred to as "mixing and defibrating step"), and the above-mentioned cotton-like mixture. A step of laminating (hereinafter referred to as "laminating step"), and a step of forming a mat by subjecting the laminated cotton-like mixture to needle punching (hereinafter, referred to as "mat")
It is called a "needle punching step". ), It is preferable that the mat is manufactured by a method for manufacturing a core material for a vacuum heat insulating material, which has a step of compression-molding by heating and compressing the mat and then cooling the mat (hereinafter referred to as “compression molding step”).

In the compression molding step, the mat may be heated and then hot pressed, and then cooled while maintaining the shape at that time to perform compression molding.

The steps will be described below.

The mixing and defibrating step and the laminating step will be described with reference to FIG.

First, in the mixing and defibrating step, the glass wool 31 having an average fiber diameter of 5 to 6 μm and the average fiber diameter of 9 to 10 are used.
The polypropylene fibers 32 of μm are mixed in a ratio of 8: 2. The defibrating device 33 uniformly mixes and defibrates the fiber mixture 34.

This is conveyed by a belt conveyor 35, and in the next laminating step, about 30 to 40 layers are laminated by a roller 36 and a cross layer device 37 to obtain a folded fiber mixture 38. This fiber mixture 38 Has a thickness of about 15 cm.

In the next needle punching step, as shown in FIG. 4, the layered product 38 of the cotton-like mixture is subjected to needle punching using a needle punching device 39.

The needle punching process is the method disclosed in
7-96563 (B32B1 / 06), as shown in the needle punching device 39, a member provided with a large number of needles (needles) having a plurality of small fishing hook-shaped barbs on the side surface is formed into the strip-shaped laminated body. Insert in a direction perpendicular to the object 38 (thickness direction), and pull up the member from that state,
By repeating the above operation, the fibers are entangled and pulled in the barb, so that the fibers inside the laminate are entangled and fixed, and the mat 40 is formed.

In this needle punching process,
Of the plurality of barbs provided on the needle (needle),
The barb provided at the most distal end of the needle does not penetrate the laminated cotton-like mixture 38, and the barb is located at a position of 50% or more and 90% or less in the depth direction of the laminated cotton-like mixture. It is particularly preferable to fasten and perform needle punching.

When the barb provided at the tip of the needle penetrates the cotton-like mixture, holes are formed in the formed mat due to the needle, which causes a decrease in heat insulation performance as the core material. It is considered to be. Therefore,
It is preferable that the barb provided at the most distal end of the needle does not penetrate to the opposite surface and is kept within the depth range described above.

Needle punching is preferably performed from the viewpoint that it is possible to form a mat excellent in handleability by compressing the cotton-like mixture without impairing the continuity in the laminate.

The mat 40 obtained by the needle punching process is fixed by the entanglement of the fibers.

The thickness of the mat 40 is about 4 cm.

Next, as shown in FIG. 5, a ceramic plate 41 as a weight is placed on the mat 40 obtained by the needle punching step, and the mat is passed through the furnace 42. In this compression molding step, the mat 40 is compressed and strongly fixed by bonding the fibers together. Furnace 42
The temperature is controlled at about 210 ℃.

By this heating and pressing, the polypropylene fiber in the mat 40 is heated, the surface of the fiber is slightly melted, and the polypropylene fiber and the glass wool are bonded and fixed.

At this time, the thickness of the mat 43 discharged from the furnace 42 is about 15 mm.

If the passage time in the furnace 42 is too long, the thermoplastic resin fibers will be melted and the communication between the fibers will be blocked, making it difficult to evacuate, which is not preferable. On the other hand, if it is too short, the adhesion at the fiber intersection will be weakened.

A core material for a vacuum heat insulating material is manufactured through the mixing and defibrating step, the laminating step, the needle punching step, and the compression molding step.

That is, 80 parts by weight of glass wool having an average fiber diameter of 5 to 6 μm and 20 parts by weight of polypropylene resin fibers having an average fiber diameter of 9 to 10 μm were mixed and defibrated to give a cotton-like mixture, The cotton-like mixture is thinly laminated in a band shape, and a cross-layer apparatus is used to obtain a laminate of the cotton-like mixture.

Next, the laminate is matted by using a needle punching device. The obtained mat was heated and compressed in a furnace and air-cooled. The compression molded mat is cut and dried.

Then, as shown in FIG. 6, the core material for a vacuum heat insulating material, which has been cut and dried, is placed in a container 18 which constitutes one surface of a container which can accommodate this core material and can maintain a vacuum inside. 44 is placed, the container 18 constituting the other surface of the container is further covered, and then heat sealing is performed on the three sides.

This is placed in a vacuum chamber (not shown) and evacuated, and the degree of vacuum in the container 18 is set to 13.3 Pa to 1.3.
The vacuum heat insulating material 45 of the present invention is formed by setting the pressure to 3 Pa (0.1 to 0.01 Torr) and heat-sealing the remaining one side.

Any container can be used as the container 18 as long as it has a gas barrier property, can be heat-sealed, and can accommodate the core material and maintain a vacuum inside. , Nylon, aluminum vapor deposition P
A container using a gas barrier film having a four-layer structure of ET (polyethylene terephthalate), aluminum foil, and high density polyethylene is preferably used.

Although only the core material 44 is put in the container 18, the vacuum heat insulating material 45 having the heat insulating performance and the decrease in the heat insulating performance can be obtained, but the heat insulating performance is deteriorated by a slight amount of outgas. It is also preferable to further encapsulate an adsorbent for prevention.

The density of the vacuum heat insulating material core material 44 in the vacuum heat insulating material 45 becomes about 300 kg / m ³ by vacuuming.

In the compression molding step of the above-mentioned example, the mat is always heated and compressed, but it is also possible to perform hot pressing after heating and then cooling while maintaining the shape at that time to perform compression molding.

This example will be described with reference to FIGS. 7 and 8.

As shown in FIG. 7, the mat 40 is placed on the hot press device 46. Hot press machine 46
Is controlled at about 190 ° C to 210 ° C.

As a result, the mat 40 is heated.

Before the polypropylene fibers are melted (3 minutes after being placed), hot pressing is performed. The distance between the hot press devices 46 is set to 15 mm, and the mat itself is compressed to reduce the volume (increase the density). This allows
The contact intersections of the pre-propylene fibers existing inside the mat and having a partially melted surface with other fibers (other pre-propylene fibers or glass wool) are fused.

The thickness of the mat 47 taken out from the hot press device 46 is elastically restored to about 17 mm. However, if it is left as it is, the mat 47
The thickness will be restored to about 25 mm.

Therefore, as shown in FIG. 8, the mat 47 is sandwiched by the press device 48 controlled at room temperature for about 3 minutes. The space between the press devices 47 is 15 mm. This press work is called cold press. Thereby, the adhesion of the mat is fixed. As a result, the vacuum heat insulating material core material 49 is formed.

Thereafter, in the same manner as described above, the core material for vacuum heat insulating material is cut, placed in a gas barrier film container, evacuated, and sealed to obtain a vacuum heat insulating material.

Next, using this cold press process, a foldable vacuum heat insulating material is prepared as shown in FIG.
~ It demonstrates, referring to FIG.

FIG. 9A is similar to FIG. 8, and the mat 47 pressed after heating is cold-pressed by the pressing device 48.

In this embodiment, as shown in FIG. 9 (b), the projections 50, 51 are added to the pressing device during this cold pressing.
To attach a recess to the mat.

The protrusion 50 is a protrusion having a triangular cross section which is recessed in a line from end to end of the mat. Its height is 10 mm
Is.

The protrusion 51 is a columnar protrusion that allows a part of the mat to be recessed into a columnar shape, and its height is 10 mm.

FIG. 10 shows a mat (core material for vacuum heat insulating material) 55 formed by this cold press.

The recess 53 is formed by the protrusion 51. The linear recess 54 is formed by the protrusion 50.

FIG. 11 shows the mat 55 cut into a predetermined size.

After the mat (vacuum heat insulating material core material) 56 is dried, a getter material is put into the recess 53. And
It is placed in the gas barrier container 18, placed in a vacuum chamber (not shown) and evacuated, and the container 18 is heat-sealed and sealed.

That is, a vacuum heat insulating material as shown in FIG. 12 is produced.

The vacuum heat insulating material 58 is easily bent from the concave portions 54, 54 of the core material 57 and can be bent as shown in FIG.

[0087]

According to the present invention, an unreacted substance, a foaming agent,
Also, it is possible to provide a vacuum heat insulating material having a small amount of impurities such as an organic binder that cause outgas, having continuity, excellent handleability and heat resistance, easy to transport, and excellent in heat insulating performance. .

Also, according to the present invention, it is possible to provide a vacuum heat insulating material which is bendable and easy to manufacture and handle.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of an example of a conventional vacuum heat insulating material.

FIG. 2 is a cross-sectional view of essential parts of a refrigerator using a conventional vacuum heat insulating material.

FIG. 3 is a diagram for explaining a method of manufacturing the vacuum heat insulating material of the present application.

FIG. 4 is a diagram for explaining a method of manufacturing the vacuum heat insulating material of the present application.

FIG. 5 is a diagram for explaining a method of manufacturing the vacuum heat insulating material of the present application.

FIG. 6 is a cross-sectional view of essential parts of an example of a vacuum heat insulating material of the present application.

FIG. 7 is a diagram for explaining another method for producing the vacuum heat insulating material of the present application.

FIG. 8 is a diagram for explaining another method of manufacturing the vacuum heat insulating material of the present application.

FIG. 9 is a diagram for explaining a method for manufacturing a bendable vacuum heat insulating material of the present application.

FIG. 10 is a view for explaining a core material for a vacuum heat insulating material before being cut, which is put in the bendable vacuum heat insulating material of the present application.

FIG. 11 is a view for explaining a core material for a vacuum heat insulating material after being cut, which is put into the bendable vacuum heat insulating material of the present application.

FIG. 12 is a cross-sectional view of a bendable vacuum heat insulating material of the present application.

FIG. 13 is a cross-sectional view of a bendable vacuum heat insulating material of the present application in a folded state.

[Explanation of symbols]

18 ... Containers 31 ... Glass wool, 32 ··· Polypropylene (thermoplastic resin fiber), 34, 38, 40 ... Mixtures, 47..mat (flat mixture), 47, 49, 55, 56..Vacuum insulation core material, 54 ... 58 ... Vacuum insulation.

Claims (5)

[Claims] 1. A mixture containing glass wool and thermoplastic resin fibers is heated at a temperature higher than the melting point of the thermoplastic resin fibers, and after this heating, pressure compression is performed, and the shape after the pressure compression is changed. In order to keep it, the core material for the vacuum heat insulating material is formed by holding the shape at a temperature lower than the melting point temperature after this compression and compression, and the formed core material for the vacuum heat insulating material is housed in a container. A vacuum heat insulating material, characterized in that the inside of the container is evacuated and then the container is sealed. 2. The vacuum heat insulating material according to claim 1, wherein the thermoplastic resin fiber is polypropylene. 3. A tabular mixture comprising glass wool and a thermoplastic resin fiber, the tabular mixture being heated at a temperature higher than the melting point of the thermoplastic resin fiber, followed by pressure compression. The core material for a vacuum heat insulating material was formed by compressing the thickness of the core material and maintaining the thickness after the compression and compression at a temperature lower than the melting point temperature after the compression and compression. A vacuum heat insulating material, characterized in that the core material for vacuum heat insulating material is housed in a container, the inside of the container is evacuated, and then the container is sealed. 4. The vacuum heat insulating material according to claim 3, wherein a linear recess is formed in the flat plate mixture when the thickness of the flat plate mixture is maintained at the low temperature. 5. A mixture of glass wool and thermoplastic resin fibers is mixed to form a tabular mixture, and the mixture is compressed by melting and adhering the intersections of the thermoplastic resin fibers contacting other fibers. At the same time, the plate-shaped mixture is provided with linear recesses to form a core material for vacuum heat insulating material, the formed core material for vacuum heat insulating material is housed in a container, and the inside of the container is evacuated. A vacuum heat insulating material formed by sealing a container.