JP6605823B2 - Heat insulation member, method for producing heat insulation member - Google Patents

Description

  The present invention relates to a heat insulating member having excellent heat insulating performance.

  Thermal insulation members are used in various fields such as automobiles, home appliances, and buildings. For example, there is a vacuum heat insulating member whose inside is evacuated. Since a vacuum heat insulation member can suppress heat conduction via gas, such as air, it has high heat insulation performance.

  As such a vacuum heat insulating member, for example, a space constituted by an outer box and an inner box includes a core material that is sealed under reduced pressure, and the volume change rate before and after the pressure reduction of the core material is 50% or less, And there exists a vacuum heat insulation box which arrange | positioned the gas adsorbent which can adsorb | suck at least nitrogen in space (patent document 1).

JP 2007-211884 A

  However, in the structure as in Patent Document 1, when the inside of the box is decompressed, the exhaust resistance between the core and the box increases, so that a long vacuum can be obtained only by exhausting with a general vacuum pump. Exhaust is required. Further, since the gas adsorbent is enclosed, the manufacturing cost increases.

  Further, when the volume change rate is large, if the holes are crushed by evacuation, the porosity is lowered and the thermal conductivity is increased, so that the performance as a heat insulating member is deteriorated.

  This invention is made | formed in view of such a problem, and it aims at providing the heat insulation member etc. which are excellent in heat insulation performance at low cost.

In order to achieve the above-mentioned object, the first invention comprises a core material and an exterior for sealing the core material, and the core material is a resin foam having a large number of closed cells, and the closed cell The resin foam is a resin foamed particle of polyethylene terephthalate, a gap is formed between the resin foamed particles, and the closed cell is decompressed, and the resin foam is expanded. The heat insulating member is characterized in that the gap is decompressed while having the voids between particles .

  The foaming ratio of the core material may be 20 times or more.

  The exterior may be a metal film formed by plating or vapor deposition on the outer periphery of the core material.

  The exterior includes an outer member and an inner member, and a part of the outer member and the inner member are overlapped and joined, and the core material is formed in a space formed by the outer member and the inner member. It may be arranged.

  The exterior includes an outer member, an inner member, and a lid member, and a part of the lid member is overlapped and joined to the outer member and the inner member, and the outer member, the inner member, and the lid member are joined. The core material may be disposed in a space formed by

  According to the first invention, since the resin foam having closed cells is used, the core material is not easily crushed. Further, since the inside of the closed cells is decompressed, the heat insulation efficiency is high without using a gas adsorbent.

  If the resin foam is made of polyethylene terephthalate resin foam particles, it can be used even at a higher temperature than other members. In addition, since polyethylene terephthalate has a low nitrogen permeability, air can be prevented from entering the closed cells during production.

  In this case, by setting the expansion ratio of the core material to 20 times or more, at a high temperature of about 120 °, for example, heat conductivity (heat insulation) that cannot be achieved with polypropylene or polystyrene can be achieved. .

  Further, the exterior can be a metal film, and in particular, by forming the metal film by vacuum deposition, it is possible to prevent air from entering the closed cells when forming the exterior outside the core material. .

  In addition, as an exterior, a core material may be arrange | positioned inside using an outer member and an inner member, and also a core material may be arrange | positioned inside using a cover material.

According to a second aspect of the present invention, there is provided a step of forming a resin foam by foaming a resin, a step of heating the resin foam under reduced pressure, and an outer periphery provided on an outer periphery of the resin foam. And the resin foam is a resin foamed particle of polyethylene terephthalate, a gap is formed between the resin foamed particles, and closed cells are formed in the resin foam. In the step of sealing the resin foam, after applying the exterior, the interior of the exterior is kept with the voids between the resin foam particles in a state where the closed cells are decompressed. By vacuuming, the foam is sealed, and the gap and the inside of the closed cells are depressurized.

  The exterior may be formed by dry plating.

  The exterior may be formed by vacuum deposition.

  According to 2nd invention, the inside of a closed cell can be pressure-reduced by heating a resin foam under pressure reduction.

  Moreover, the structure is simple by forming the exterior with a metal film by plating or vacuum deposition.

  ADVANTAGE OF THE INVENTION According to this invention, the heat insulation member etc. which are low cost and excellent in heat insulation performance can be provided.

(A) is sectional drawing which shows the heat insulation member 1, (b) is a conceptual diagram of the resin foam 7, (c) is a conceptual diagram which shows the closed cell 9. FIG. (A) is the conceptual diagram which shows the state which put the resin particle 13 in the shaping | molding die 11, (b) is the conceptual diagram which shows the state which made the resin particle foam, (c) is the resin foam 7 in a heating furnace. The conceptual diagram which shows the state which has arrange | positioned, (d) is a conceptual diagram which shows the state which covers the resin foam 7 with the exterior | packing 3. FIG. The figure which shows the relationship between the expansion ratio by a material, and 10% compressive stress. (A) is a figure which shows the relationship between the foaming magnification by a material and thermal conductivity in normal temperature, (b) is a figure which shows the relationship between the foaming magnification by a material and thermal conductivity in 120 degreeC. Sectional drawing which shows the heat insulation member 1a. Sectional drawing which shows the heat insulation member 1b. Sectional drawing which shows the heat insulation member 1c.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view showing the heat insulating member 1. The heat insulating member 1 includes an exterior 3 and a core material 5. A core material 5 is disposed inside the exterior 3. Moreover, the inside of the exterior 3 is decompressed.

  The exterior 3 may be made of a gas barrier material, and is made of metal, for example. The exterior 3 may be a flexible material such as a laminate film of metal and resin, or may be a rigid material such as a metal plate. Moreover, although mentioned later for details, the metal film formed in the outer peripheral surface of the core material 5 may be sufficient. Thus, as long as the exterior 3 can seal the core material 5, the material and the form are not limited.

  The core material 5 is composed of a resin foam 7. FIG. 1B is an enlarged view of a part A in FIG. 1A, and is a conceptual diagram of the resin foam 7. The resin foam 7 is a member in which a plurality of resin foam particles 7a are assembled and integrated. A minute gap is formed between the resin foam particles 7a. This gap is in a state where the pressure is reduced by the pressure reduction in the exterior 3.

  FIG. 1C is an enlarged view of part B of FIG. 1B and is a conceptual diagram showing closed cells 9. A large number of minute closed cells 9 are formed inside the resin foam particles 7a. In the present invention, the inside of the closed cell 9 is depressurized. That is, only by evacuating the inside of the exterior 3, the gap between the resin foam particles 7 a can be reduced, but the inside of the closed cells 9 cannot be reduced in a short time. The resin foam 7 is left in a high-temperature and reduced-pressure atmosphere for a predetermined time to sufficiently depressurize the inside of the closed cells 9, and then returned to room temperature and normal pressure. By sealing, the inside of the closed cell 9 is depressurized.

  In addition, although the material of the resin foam particle 7a (resin foam 7) is not ask | required, a polyethylene terephthalate, a polycarbonate, etc. are applicable, for example. Polyethylene terephthalate and polycarbonate are superior in scratch resistance because they can be used at higher temperatures and have higher hardness than polypropylene and polystyrene.

  Next, the manufacturing method of the heat insulation member 1 is demonstrated. First, as shown in FIG. 2A, the resin particles 13 are put in the mold 11. The resin particles 13 are preliminarily infiltrated with gas. In this state, the resin particles 13 are foamed by heating to a predetermined temperature. Although the heating temperature depends on the material, for example, in the case of polyethylene terephthalate, it is heated to about 160 ° C. to 170 ° C. By heating, the resin particles 13 are foamed, and the surfaces of the foamed resin foam particles 7a are joined and integrated.

  At this time, as shown in FIG. 2B, the resin particles 13 are integrated into the cavity shape of the mold 11. That is, in the present invention, the resin foam 7 having an arbitrary three-dimensional shape can be molded depending on the shape of the mold 11.

  Next, the obtained resin foam 7 is taken out and placed in a heating furnace. The inside of the heating furnace can be decompressed by the decompression device 15. The inside of the closed cell inside the resin foam 7 can be decompressed by depressurizing the inside of the heating furnace in the heated state.

  The heating temperature is a temperature lower than the softening temperature of the material and is, for example, about 60 to 70 ° C. If the temperature is too low, degassing of the closed cells cannot be performed, and if the temperature is too high, the resin foam 7 is crushed. The degree of vacuum is, for example, about 0.5 Pa (or normal pressure—about 100 kPa). The heating and decompression time is about 24 hours.

  Next, as shown in FIG. 2 (d), the resin foam 7 is brought to room temperature, then returned to normal pressure, and sealed with the exterior 3. That is, the resin foam 7 is disposed in the exterior 3 and the exterior 3 is sealed while being evacuated. The degree of vacuum is, for example, about 0.5 Pa (or normal pressure—about 100 kPa).

  Here, if the state in which the resin foam 7 is returned to the normal temperature and the normal pressure is maintained for a long time, air enters into the reduced closed cells, and therefore the resin foam 7 is returned to the normal temperature and the normal pressure. It is desirable to perform the sealing work in as short a time as possible. If the resin foam 7 is made of polyethylene terephthalate, the nitrogen permeability is extremely low, so that the infiltration of air into the closed cells can be suppressed. As described above, the heat insulating member 1 can be manufactured.

  Next, the expansion ratio of the resin foam 7 will be examined. FIG. 3 is a diagram showing the relationship between 10% compression stress and expansion ratio for polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS). Here, the expansion ratio is a ratio obtained by dividing the density of the resin foam particles before foaming by the density of the resin foam after foaming. As shown in the figure, the 10% compressive stress decreases as the expansion ratio increases. This is because the porosity increases and the strength decreases as the expansion ratio increases. Here, the 10% compression stress is a force required to reduce the volume of the foam by 10%.

  If PET has the same expansion ratio as compared with other materials, the strength is high. For example, if the resin foam 7 is disposed in the exterior 3 and the pressure is reduced to about 0.5 kPa, the pressure is reduced to about 100 kPa with respect to the normal pressure. For this reason, if the 10% compressive stress has a strength of 100 kPa (C in the figure) or higher, the volume change rate can be reduced to 10% or less when the inside of the exterior 3 is decompressed. For example, in the case of PET, if the expansion ratio is about 60 times, the volume change rate can be about 10% even when the pressure is reduced by about 100 kPa with respect to normal pressure.

  FIG. 4A is a diagram showing the relationship between the expansion ratio and the thermal conductivity (W / mK) at room temperature. In order to improve the heat insulation performance by lowering the thermal conductivity, it is required not only to increase the expansion ratio but also to increase the compressive strength of the core material in order to keep the compressibility during vacuum small. This is because if the compressive strength is low, the core material bubbles are crushed by the negative pressure when the inside of the exterior is evacuated, the porosity is lowered, and the heat insulation performance is significantly lowered.

  As shown in FIG. 4 (a), looking at the relationship between the expansion ratio at normal temperature and the thermal conductivity, if the resin foam of PET, compared with other materials, the expansion ratio is 50 times or more. The thermal conductivity can be made lower than that of the material.

  On the other hand, FIG.4 (b) is a figure which shows the relationship between the foaming magnification by a material, and thermal conductivity (W / mK) in 120 degreeC. For example, considering use in a car engine room or the like, heat insulation performance at a temperature of about 120 ° C. is required.

  At 120 ° C., the strength of PET is almost the same as that at normal temperature, but the strength of PP and PS is greatly reduced compared to that at normal temperature. For this reason, the expansion ratio with the smallest thermal conductivity is smaller than that at room temperature. As a result, PET can achieve a lower thermal conductivity than the lowest thermal conductivity in PP and PS (D in the figure). In addition, if it is PET, it can be used also at 150 degreeC.

  For example, in the figure, the curve of D and the PET generally intersect at an expansion ratio of 20 times. Therefore, by setting the expansion ratio to 20 times or more, thermal conductivity that cannot be obtained with PP or PS at 120 ° C. can be obtained. For this reason, when PET is selected as the material of the resin foam 7, it is desirable that the expansion ratio is 20 times or more.

  Even in the case of PET, when the expansion ratio is increased, the strength is lowered, the closed cells are easily crushed, and the thermal conductivity is increased. That is, the PET curve exceeds the straight line D when the expansion ratio is about 130 times or more. For this reason, when PET is used, it is possible to obtain heat insulation performance that cannot be obtained with PP or PS by setting the expansion ratio in the range of 20 times to 130 times (E in the figure). In consideration of manufacturability and the like, the upper limit of the expansion ratio is preferably 100 times or less.

  As described above, according to the present embodiment, there is a gap between the resin foam particles 7 a, and this gap can serve as an air flow path when exhausting the interior of the exterior 3. An increase in exhaust resistance between the two can be suppressed. For this reason, evacuation can be performed in a short time, and a gas absorbent or the like is unnecessary.

  Moreover, since the inside of the closed cell 9 is in a depressurized state, the heat insulating properties are good even when compared with the case where a conventional resin foam is used.

  Moreover, if the resin foam 7 is made of PET, it can be used even at high temperatures. Moreover, since PET has a very low nitrogen permeability, it is possible to suppress the intrusion of air into closed cells during production.

  Moreover, PET can obtain thermal conductivity that cannot be obtained with PP or PS at high temperatures. In particular, at 120 ° C., the strength of both PP and PS decreases, so the foaming ratio is 20 times or more, which is superior to other materials. Further, since the expansion ratio can be increased and the compressive stress can be maintained as compared with other materials, high heat insulation performance can be exhibited. At the same time, weight reduction can be achieved, and the material cost can be reduced.

  Next, a second embodiment will be described. FIG. 5 is a cross-sectional view showing the heat insulating member 1a. In addition, in the following description, about the structure which show | plays the function similar to the heat insulation member 1, the code | symbol same as FIG. 1 etc. is attached | subjected and the overlapping description is abbreviate | omitted.

  Although the heat insulation member 1a is the structure substantially the same as the heat insulation member 1, the form of the exterior 3 is different. The exterior 3 of the heat insulating member 1a includes an inner member 3a and an outer member 3b. The inner member 3a and the outer member 3b are made of a metal plate, and are manufactured by drawing, for example.

  The inner member 3a and the outer member 3b are both box-shaped members, and have a flange portion whose upper edge portion is bent outward. The inner member 3a is smaller in size than the outer member 3b. For this reason, when the flange part of the outer member 3b is superimposed on the lower surface of the flange part of the inner member 3a, a space is formed between the inner member 3a and the outer member 3b.

  A space between the inner member 3a and the outer member 3b is filled with a core material 5 that has been previously formed into a space shape and subjected to a vacuum heat treatment. That is, the core material 5 is formed into a box shape.

  The flange portions are joined by welding, for example. At this time, it is possible to keep the space in a vacuum by performing welding while evacuating the space. Moreover, even if the pressure in the space is reduced to about normal pressure −100 kPa, for example, by setting the expansion ratio of the PET core material 5 to about 60 times or less, the deformation rate of the core material 5 is set to 10% or less. Can do.

  According to the second embodiment, an effect similar to that of the first embodiment can be obtained. Moreover, a heat insulation container can be obtained by making the exterior 3 into a container shape.

  Next, a third embodiment will be described. FIG. 6 is a view showing the heat insulating member 1b. The heat insulating member 1b has substantially the same configuration as the heat insulating member 1, but the form of the exterior 3 is different. The exterior 3 of the heat insulating member 1b includes an inner member 3a, an outer member 3b, and a lid member 3c. The inner member 3a, the outer member 3b, and the lid member 3c are made of a metal plate, and are manufactured by drawing, for example.

  The inner member 3a and the outer member 3b are both box-shaped members that are open upward, and the inner member 3a is smaller in size than the outer member 3b. For this reason, when the inner member 3a is disposed inside the outer member 3b, a space is formed between the inner member 3a and the outer member 3b.

  The space between the inner member 3a and the outer member 3b is filled with a core material 5 that has been previously formed into a space shape and subjected to a vacuum heat treatment. That is, the core material 5 is formed into a box shape.

  In addition, the lid member 3c is arrange | positioned in the opening part between the inner side member 3a and the outer side member 3b, the outer edge part of the lid member 3c and the outer side member 3b are joined, the inner edge part of the lid member 3c, the inner side member 3a, Are joined. At this time, it is possible to keep the space in a vacuum by performing welding while evacuating the space.

  According to the third embodiment, the same effect as that of the first embodiment can be obtained. Thus, in the present invention, the shape of the exterior 3 is not limited.

  Next, a fourth embodiment will be described. Fig.7 (a) is sectional drawing which shows the heat insulation member 1c, FIG.7 (b) is the F section enlarged view of Fig.7 (a). The heat insulating member 1c has substantially the same configuration as the heat insulating member 1, but the form of the exterior 3 is different. The exterior 3 of the heat insulating member 1c is composed of a metal film 3d.

The metal film 3d can be formed by, for example, dry plating or vacuum deposition. In this case, the metal film 3d may be formed on the outer peripheral surface of the core material 5 that has been formed into an arbitrary shape (for example, a box shape) and subjected to vacuum heat treatment. The thickness of the metal film 3d is only required to have gas barrier performance. For an aluminum foil (for example, 7 μm and oxygen permeability is 0.01 cc / m ² · day · atm (20 ° C.)), for example, about 10 μm. Good.

  If the metal film 3d is formed by vacuum deposition, the core material 5 after the vacuum heat treatment can be formed in the vacuum container, so that air penetrates into the core material 5 after the vacuum heat treatment. This can be suppressed.

  According to the fourth embodiment, the same effect as that of the first embodiment can be obtained. Thus, in the present invention, the aspect of the exterior 3 is not limited.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c ......... Heat insulation member 3 ......... Exterior 3a ......... Inner member 3b ......... Outer member 3c ......... Cover member 5 ......... Core material 7 ......... Resin foam 7a ... ... Resin foam particles 9 ... Closed cells 11 ... Mold 13 ... Resin particles 15 ... Pressure reducing device

Claims (8)

A core material,
An exterior for sealing the core material;
Comprising
The core material is a resin foam having a large number of closed cells,
The inside of the closed cell is depressurized,
The resin foam is a resin foam particle of polyethylene terephthalate,
A gap is formed between the resin foam particles,
The heat insulating member , wherein the gap is decompressed while the voids between the resin foam particles are kept in a state where the closed cells are decompressed .   The heat insulating member according to claim 1, wherein a foaming ratio of the core material is 20 times or more.   The heat insulating member according to claim 1, wherein the exterior is a metal film formed on the outer periphery of the core member by plating or vapor deposition.   The exterior includes an outer member and an inner member, and a part of the outer member and the inner member are overlapped and joined, and the core material is formed in a space formed by the outer member and the inner member. The heat insulating member according to claim 1, wherein the heat insulating member is disposed.   The exterior includes an outer member, an inner member, and a lid member, and a part of the lid member is joined to the outer member and the inner member to form the outer member, the inner member, and the lid member. The heat insulating member according to claim 1, wherein the core material is disposed in the open space. Forming a resin foam by foaming a resin;
Heating the resin foam under reduced pressure;
Providing an exterior on the outer periphery of the resin foam and sealing the resin foam;
Comprising
The resin foam is a resin foam particle of polyethylene terephthalate,
A gap is formed between the resin foam particles,
Closed cells are formed in the resin foam,
In the step of sealing the resin foam, after applying the exterior, the interior of the exterior is evacuated while the closed cells are decompressed and the voids between the resin foam particles are left. By doing this, the said foam is sealed, The said clearance gap and the inside of the said independent bubble are pressure-reduced, The manufacturing method of the heat insulation member characterized by the above-mentioned.   The method for manufacturing a heat insulating member according to claim 6, wherein the exterior is formed by dry plating. The method for manufacturing a heat insulating member according to claim 6, wherein the exterior is formed by vacuum deposition.

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