JP2012013158A - Vacuum heat insulating material, heat insulating box, and method of manufacturing vacuum heat insulating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vacuum heat insulating material that can improve heat insulating performance, and to provide a heat insulating box and a method of manufacturing the vacuum heat insulating material.SOLUTION: The vacuum insulating material 10 includes a nonwoven core material 11 and a resin film 12 for vacuum-sealing the nonwoven core material 11. The nonwoven core material 11 is formed of a resin fiber. Polystyrene whose weight average molar weight is 100,000 to 180,000 is selected as a material of the resin fiber. Thus, fiber spinning stability is improved and thread breakage occurring at fiber spinning can be suppressed. As a result, a large-diameter fiber which is not drawn yet and not fined is hardly mixed into the nonwoven core material 11, and the deterioration of the heat insulating performance of the vacuum heat insulating material 10 is suppressed. Furthermore, the breakage of the resin film 12 caused by the large-diameter fiber hardly occurs, and the deterioration of the heat insulating performance of the vacuum heat insulating material 10 is further suppressed.

Description

  The present invention relates to a vacuum heat insulating material having an aggregate of resin fibers as a core, a heat insulating box provided with the vacuum heat insulating material, and a method for manufacturing the vacuum heat insulating material.

  A conventional vacuum heat insulating material using a resin fiber as a core material is manufactured by laminating a plurality of non-woven fabrics of resin fibers cut into a required shape to form a core material, and vacuum-sealing this with a resin film to integrate them (for example, Patent Document 1). Such a vacuum heat insulating material is superior in heat insulating performance as compared with a heat insulating material made of glass wool or foamed urethane, and is being applied to a cooling device such as a refrigerator, a heat insulation box, or a water heater. In addition, resin nonwoven fabrics are often composed of resin fibers such as polypropylene and polyethylene terephthalate, but there are also nonwoven fabrics composed of polystyrene resin fibers (see, for example, Patent Document 2).

JP 2006-17151 A JP-A-11-181664

  In order to produce a vacuum heat insulating material in which a nonwoven fabric made of polystyrene is used as a core material and this is vacuum-sealed with a resin film and integrated, it is first necessary that the polystyrene be fiberized and processed into a nonwoven fabric form. . Here, the nonwoven fabric using polystyrene is produced by a technique in which polystyrene is fiberized by a melt spinning method such as a spunbond method, and the obtained fibers are laminated. However, since polystyrene has low spinning stability, yarn breakage tends to occur during spinning. For this reason, there existed a problem that the fiber with a large diameter which has not been stretched | stretched by unstretched mixed in a nonwoven fabric, and heat insulation performance fell. In addition, a fiber having a large diameter also causes damage to the packaging material, and further has a problem that the heat insulation performance is lowered.

  This invention was made in order to solve the above problems, and its purpose is to provide a vacuum heat insulating material, a heat insulating box, and a vacuum heat insulating material manufacturing method capable of improving heat insulating performance. Is to provide.

  The vacuum heat insulating material according to the present invention includes a core material which is a nonwoven fabric laminate formed of resin fibers made of polystyrene having a weight average molecular weight of 100,000 or more and 180,000 or less, and a resin film for vacuum-sealing the core material. ing.

  According to the vacuum heat insulating material of the present invention, a vacuum heat insulating material with improved heat insulating performance can be provided.

It is the schematic which shows the structure of a vacuum heat insulating material. It is a flowchart which shows the manufacturing process of a vacuum heat insulating material. It is the schematic which shows the structure of the manufacturing apparatus of a nonwoven fabric (core material). It is the schematic which shows the structure of a heat insulation box. It is the schematic which shows the other structure of a heat insulation box.

(Embodiment 1)
Based on FIG. 1, FIG. 2, the structure of the vacuum heat insulating material in one embodiment of this invention is demonstrated. FIG. 1 is a schematic view of a vacuum heat insulating material 10 produced using a resin nonwoven fabric as a core material. The vacuum heat insulating material 10 includes a nonwoven fabric core material 11 and a resin film 12 for vacuum-sealing the nonwoven fabric core material 11. Here, the state in which the resin film 12 vacuum seals the nonwoven fabric core material 11 is that the nonwoven fabric core material 11 is surrounded by the resin film 12 and the interior surrounded by the resin film 12 is held at a pressure lower than atmospheric pressure. State. Although the specific internal pressure surrounded by the resin film 12 is not particularly limited, the internal pressure may be reduced to a degree of vacuum of 1 Pa (Pascal), for example. The nonwoven fabric core material 11 is comprised from the resin fiber. As the material of the resin fiber, polystyrene having a weight average molecular weight of 100,000 to 180,000 is selected. Thereby, the spinning stability of polystyrene is improved, and yarn breakage that occurs during spinning can be suppressed. For this reason, in the vacuum heat insulating material 10 in this Embodiment, the fiber with a large diameter which is not extended | stretched and is not refined is difficult to mix in a nonwoven fabric, and the fall of heat insulation performance is suppressed. Furthermore, it is difficult for the packaging material to be damaged by the fiber having a large diameter, and the deterioration of the heat insulation performance is further suppressed. As a result, the vacuum heat insulating material 10 in the present embodiment is a vacuum heat insulating material with improved heat insulating performance.

  The resin film 12 is a synthetic resin film formed into a thin film shape (film shape). Examples of the material of the resin film 12 include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyester, polycarbonate, polystyrene, ethylene-vinyl acetic acid copolymer, ethylene-vinyl alcohol copolymer, ethylene-methacrylic acid. A copolymer or the like can be employed. Further, for example, a metal laminate film covered with a metal foil film such as aluminum may be used as the resin film 12.

  Next, with reference to FIG. 1 and FIG. 2, the manufacturing method of the vacuum heat insulating material 10 is demonstrated. First, a raw material preparation step is performed as a step (S10). In this step (S10), polystyrene, which is a raw material of the nonwoven fabric core material 11, is prepared. Next, a melt spinning step is performed as a step (S20). In this step (S20), resin fibers are produced by, for example, a melt spinning method. As the melt spinning method, for example, a spunbond method can be employed. Next, a sheet forming process is performed as a process (S30). In this step (S30), a resin nonwoven fabric is produced from the resin fibers.

  Next, a lamination process is implemented as process (S40). In this step (S40), referring to FIG. 1, the resin nonwoven fabric produced in step (S30) is laminated to produce nonwoven fabric core material 11. And a vacuum sealing process is implemented as process (S50). In this step (S50), the nonwoven fabric core material 11 is vacuum-sealed with the resin film 12, and the vacuum heat insulating material 10 is produced.

  Next, a process (S20) and a process (S30) are explained in full detail based on FIG. First, an example of an apparatus for performing the steps (S20) and (S30) will be described. The nonwoven fabric manufacturing apparatus 90 used in the present embodiment includes a melt spinning apparatus 30, a belt conveyor 41, a heat fusion roll 42, and a winding roll 43. The melt spinning in the step (S20) is performed using the melt spinning apparatus 30 included in the nonwoven fabric manufacturing apparatus 90. The melt spinning device 30 melts and extrudes the resin, an extruder 31, an extrusion die 32 having a plurality of pore nozzles for fiberizing the extruded resin, and a resin discharged from the extrusion die 32. A stretching unit 33 is included. The pore nozzle of the extrusion die 32 has a configuration in which, for example, five rows of pores each having 100 holes are arranged. Further, the belt conveyor 41, the heat fusion roll 42, and the take-up roll 43 are arranged so as to wind up the nonwoven fabric 21 in a direction perpendicular to the direction in which the pores of 100 holes are arranged. Thereby, it is possible to produce a nonwoven fabric having a width of 100 holes. This configuration is one configuration example of an apparatus for producing a nonwoven fabric core material, and does not limit the configuration of an apparatus that can be used.

  Next, a specific procedure of steps (S20) and (S30) will be described. In the step (S20), first, polystyrene is supplied to the extruder 31 as the material of the resin fiber 22. The supplied polystyrene is heated to, for example, 270 ° C. to be in a molten state, and is supplied to the extrusion die 32 by the extruder 31 in a certain amount. As a result, the melted polystyrene is discharged in the form of fibers from the pore nozzles of the extrusion die 32. The linear molten resin is stretched by the stretching unit 33 and is thinned and solidified into a thin fiber shape. More specifically, for example, after the molten polystyrene is cooled by cooling air, the resin fiber 22 is produced by pulling it with an ejector that flows a high-speed air flow.

  In the step (S30), the resin fibers 22 refined by the stretching unit 33 are laminated on the belt conveyor 41 to form the resin nonwoven fabric 21. Further, the resin nonwoven fabric 21 on the belt conveyor 41 is embossed by a heat-sealing roll 42. Embossing is performed by penetrating and fusing part of the nonwoven fabric surface. In this way, the resin nonwoven fabric 21 is made into a sheet, and the yarn is less likely to be unwound. The resin nonwoven fabric 21 produced by the heat-sealing roll 42 is wound up by the winding roll 43.

  Next, the step (S40) and the step (S50) will be described in detail. In the step (S40), the resin nonwoven fabric 21 wound on the winding roll 43 in the previous step is cut after being rewound to a necessary length. With reference to FIG. 1, the nonwoven fabric core material 11 is produced by laminating | stacking the required number of resin nonwoven fabrics 21 cut | disconnected in this way. And in the process (S50), the whole nonwoven fabric core material 11 is wrapped with the resin film 12. FIG. The vacuum heat insulating material 10 is produced by vacuum-sealing and integrating them. The vacuum sealing is performed, for example, by sealing the opening of the resin film 12 by heat-sealing it in a vacuum chamber.

  Here, as a raw material prepared in the step (S10), polystyrene having a weight average molecular weight of 100,000 to 180,000 is adopted. Thereby, the spinning stability of polystyrene can be improved and yarn breakage occurring in the step (S20) can be suppressed. For this reason, the resin fiber 22 with a large diameter which is not stretched and not thinned is hardly mixed in the resin nonwoven fabric 21, and a decrease in the heat insulation performance of the vacuum heat insulating material 10 is suppressed. Furthermore, the resin film 12 is not easily damaged by the resin fibers 22 having a large diameter, and the deterioration of the heat insulation performance is further suppressed. As a result, according to the manufacturing method of the vacuum heat insulating material in the present embodiment, the vacuum heat insulating material 10 with improved heat insulating performance can be manufactured.

  Moreover, when the melt spinning of polystyrene is carried out without adding an additive for reducing the resin viscosity in the step (S20), it is preferable to select polystyrene having a weight average molecular weight of 100,000 to 160,000 as a raw material. Thereby, the spinning stability of polystyrene can be further improved. On the other hand, when polystyrene having a weight average molecular weight of 160,000 to 180,000 is selected as a raw material, it is preferable that an additive for reducing the resin viscosity is added in the step (S20) to carry out polystyrene melt spinning. Thereby, even when polystyrene having a relatively large weight average molecular weight is adopted as a raw material, the spinning stability of polystyrene can be improved. Also, when using polystyrene having a weight average molecular weight of 100,000 to 160,000, an additive for reducing the resin viscosity may be added. Thereby, it is possible to perform spinning at a low resin temperature. Here, the additive for reducing the resin viscosity is not particularly limited, and for example, aliphatic amide-based stearamide or metal soap-based metal stearate can be employed. In addition, as a raw material of the nonwoven fabric core material 11, you may select the polystyrene of a new material, but you may select the recycled polystyrene obtained by preparing a preformed product and re-pelletizing.

  Moreover, it is preferable that the fiber diameter of the resin fiber 22 is 5-20 micrometers, and the fiber diameter may be 10 micrometers by the condition setting of the melt spinning apparatus 30, for example. If the fiber diameter of the resin fiber 22 is less than 5 μm, yarn breakage is likely to occur during spinning, whereas if the fiber diameter of the resin fiber 22 exceeds 20 μm, the heat insulation performance is lowered. Therefore, considering the balance between spinnability and heat insulation performance, the fiber diameter of the resin fiber 22 is preferably 5 to 20 μm.

  In addition, referring to FIG. 1, gas adsorbent 13 may be enclosed in resin film 12 together with nonwoven fabric core material 11. Thereby, the fall of the vacuum degree in the resin film 12 can be suppressed, and the fall of heat insulation performance can be suppressed.

(Embodiment 2)
FIG. 4 is a schematic view of the heat insulation box 50 in one embodiment of the present invention. The heat insulation box 50 constitutes a cooling device such as a refrigerator, a heat storage, a water heater, for example. The heat insulating box 50 has a structure in which, for example, the vacuum heat insulating material 10 described in the first embodiment is disposed between the inner box 51 and the outer box 52. For example, the inner box 51 is made of acrylonitrile-butadiene-styrene copolymer resin, and the outer box 52 is made of an iron thin plate. In the present embodiment, the vacuum heat insulating material 10 is installed so as to occupy a part of the space (heat insulating space) between the inner box 51 and the outer box 52, and the urethane foam heat insulating material 53 is installed in the remaining space. . According to the heat insulating box 50 in the present embodiment, the vacuum heat insulating material of the present invention including the vacuum heat insulating material 10 of the first embodiment in which the deterioration of the heat insulating performance is suppressed is disposed in the heat insulating space, thereby insulating the heat. An insulating box with stable performance can be provided.

  In the present embodiment, the vacuum heat insulating material 10 is installed in contact (close contact) with the inner box 51, but it is not necessary to be limited to this embodiment, and the vacuum heat insulating material 10 contacts (contacts) the outer box 52. Even if it is installed, it may be installed without contacting the inner box 51 and the outer box 52 using a spacer or the like. Moreover, in the said embodiment, the vacuum heat insulating material 10 is installed so that it may occupy a part between the inner box 51 and the outer box 52, and the urethane foam heat insulating material 53 is installed in the remaining space. However, a heat insulating material other than urethane foam may be installed.

(Embodiment 3)
The heat insulation box of the third embodiment basically has the same configuration as the heat insulation box of the second embodiment, and has the same effect. However, the heat insulation box 50 in the third embodiment, as shown in FIG. 5, is that the vacuum heat insulating material 10 is installed so as to fill the space between the inner box 51 and the outer box 52. This is different from the second embodiment. Thereby, the heat insulation performance of the heat insulation box 50 in Embodiment 3 further improves.

  Table 1 shows the evaluation results of spinnability when polystyrenes having different weight average molecular weights were spun by the melt spinning apparatus shown in FIG. As test conditions, the resin was melted at 270 ° C., discharged from a fine nozzle with a diameter of 0.4 mm at a discharge rate of 0.55 cc / min, and stretched at 3500 mm / min by a stretching unit. At this time, the spinning stability is visually observed, A when the yarn breakage does not occur for 3 minutes, A if the yarn breakage is less than 10 times in 3 minutes, B if the yarn breakage in 3 minutes is 10 times or more Was rated C. From Table 1, it can be seen that polystyrene having a weight average molecular weight of 100,000 to 180,000 has stable spinnability. Moreover, it can be said that it is preferable to make a weight average molecular weight into 120,000 or more and 170,000 or less in order to stabilize prevention more.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The manufacturing method of the vacuum heat insulating material, the heat insulating box, and the vacuum heat insulating material of the present invention can be applied particularly advantageously to the vacuum heat insulating material, the heat insulating box, and the manufacturing method of the vacuum heat insulating material that are required to improve heat insulating performance.

  DESCRIPTION OF SYMBOLS 10 Vacuum heat insulating material, 11 Nonwoven fabric core material, 12 Resin film, 13 Gas adsorbent, 21 Resin nonwoven fabric, 22 Resin fiber, 30 Melt spinning device, 31 Extruder, 32 Extrusion die, 33 Stretching unit, 41 Belt conveyor, 42 Heat Fusing roll, 43 winding roll, 50 heat insulating box, 51 inner box, 52 outer box, 53 urethane foam heat insulating material, 90 nonwoven fabric manufacturing apparatus.

Claims (8)

A core material which is a nonwoven fabric laminate formed of resin fibers made of polystyrene having a weight average molecular weight of 100,000 to 180,000;
A vacuum heat insulating material comprising a resin film for vacuum-sealing the core material.   The vacuum heat insulating material according to claim 1, wherein the resin fiber has a diameter of 5 μm or more and 20 μm or less. An outer box,
An inner box arranged so as to be surrounded by the outer box,
The heat insulation box which the vacuum heat insulating material of Claim 1 or 2 is installed in the heat insulation space which is the space between the said outer box and the said inner box.   The heat insulation box of Claim 3 with which the said vacuum heat insulating material is installed so that the said heat insulation space may be satisfy | filled. Preparing a polystyrene having a weight average molecular weight of 100,000 to 180,000,
Forming a resin fiber by melt spinning the polystyrene;
Forming a resin nonwoven fabric by sheeting the resin fibers;
Laminating the resin nonwoven fabric to form a core material;
The vacuum insulation material manufacturing method provided with the process of vacuum-sealing the said core material with a resin film.   The method for producing a vacuum heat insulating material according to claim 5, wherein in the step of forming the resin fiber, the polystyrene to which an additive for reducing the resin viscosity is added is melt-spun.   The manufacturing method of the vacuum heat insulating material of Claim 5 or 6 whose weight average molecular weights of the said polystyrene are 100,000 or more and less than 160,000.   The manufacturing method of the vacuum heat insulating material of Claim 6 whose weight average molecular weights of the said polystyrene are 160,000 or more and 180,000 or less.

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