JP2008295721A - Electric kettle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric kettle capable of reducing possibility of causing pinholes in a vacuum heat insulating material used for a heat insulating material, and also enhancing the reliability of heat seal. <P>SOLUTION: The electric kettle includes: an outer case 1; a blind cylindrical inner container 2 arranged inside the outer case 1 and storing hot water; a lid for covering at least the partial upper surface of the outer case 1 and the upper surface opening of the inner container 2; and the vacuum heat insulating material 3 where a core material is tightly sealed in a vacuum state with the use of jacket materials having thermofusion layers on the inner surfaces, the facing jacket materials in the circumference of the core material are thermally fused, and also which is arranged between the inner container 2 and the outer case 1. A vacuum heat insulating container having a vacuum layer in the wall is used for the inner container. Low-density polyethylene is used for the thermofusion layers. The thermally fused part of the facing jacket materials in the circumference of the core material in the vacuum heat insulating material 3 is bent outward of the container 2. An evaporated film is used for the gas barrier layer of the jacket materials positioned between the core material and the inner container. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a jar pot using a vacuum heat insulating material as a heat insulating material.

  Conventionally, this type of jar pot is provided with a water storage container, a heater for heating the water in the water storage container, and a hot water discharge passage for discharging water to the outside, and the core material is an outer cover made of a heat-resistant laminate film. It has a vacuum heat insulating material covered with a material and sealed in a vacuum, and the laminate film consists of a heat-welded layer, a gas barrier layer, and a protective layer from the inside and folds the heat seal part of the vacuum heat insulating material so that it is close to the outside of the electric water heater (For example, refer to Patent Document 1).

Further, the core material is made of an inorganic fiber core material with respect to the adherent member having the curved surface portion, and the plate-like vacuum heat insulating material having a thickness of 0.1 to 6 mm is deformed along the curved surface portion of the adherend member. Some are fixed in a state (see, for example, Patent Document 2).
Japanese Patent No. 3590720 JP 2007-50521 A

  However, in the above conventional configuration, since a polypropylene is used for the heat-welded layer of the laminate film, particularly as a heat-resistant laminate film of a vacuum heat insulating material, a fiber-based core material such as glass fiber is used as the core material. In particular, when processing into a cylindrical shape, glass fiber, which is the core material, may pierce the laminate film from the inside and generate pinholes, so careful attention must be paid to processing conditions and management It had the problem that.

  In addition, as the heat-resistant laminate film of vacuum insulation material, polypropylene is used for the heat-bonding layer of the laminate film, so the melting point of polypropylene is as high as about 180 ° C. When making films, the heat seal temperature must be raised above the melting point of polypropylene, and the heat seal strength is difficult to stabilize, so the range of temperature conditions for bag making is narrow and management is very strict. Had.

  In addition, since a gas barrier film made of high-density polyethylene resin is used as the outer cover material in the past, especially when a fiber-based core material such as glass fiber is used as the core material, especially when processed into a cylindrical shape In addition, there is a problem that the glass fiber as the core material may pierce the laminate film from the inside to generate a pinhole.

  In addition, since a gas barrier film made of high-density polyethylene resin is used as the outer cover material in the past, the high-density polyethylene has a high melting point of about 132 to 135 ° C. When making a laminate film, the heat seal temperature must be raised above the melting point of high-density polyethylene, and there is a problem that heat seal stability at low temperatures is insufficient and the heat seal strength varies. Was.

  The present invention solves the above-described conventional problems, and provides a jar pot that can reduce the possibility of pinhole generation in a vacuum heat insulating material used as a jar pot heat insulating material and can improve the reliability of heat sealing. For the purpose.

  In order to achieve the above object, the jar pot of the present invention uses a vacuum heat insulating container having a vacuum layer in the wall for the inner container, and has a low thermal insulation layer for the vacuum heat insulating material disposed between the inner container and the outer case. Density polyethylene was used.

  As a result, since the vacuum insulation container is used for the inner container, the temperature outside the inner container when using the jar pot is lower than that of the inner container not using the vacuum insulation container. Even if low density polyethylene is used for the material, the temperature of the jacket material when using the jar pot is lower than the temperature at which the low density polyethylene melts. By using low density polyethylene, polypropylene and high density polyethylene can be used. Compared with the case of use, the mechanical strength such as pinhole resistance, heat seal strength, tensile / impact strength, etc. of the laminate film is further improved, so the quality of the vacuum insulation material is improved and the productivity of the jar pot is improved. To do.

  The jar pot of the present invention further improves the quality of the vacuum heat insulating material and improves the productivity of the jar pot by using a vacuum heat insulating container for the inner container and using low density polyethylene for the heat welding layer of the vacuum heat insulating material. I can do it.

  The invention of the jar pot according to claim 1 of the present invention is an outer case, an inner container having a bottomed cylindrical shape that is disposed inside the outer case and stores hot water, and a jacket material having a heat welding layer on the inner surface. A jar pot comprising a vacuum heat insulating material disposed between the inner container and the outer case, wherein the core material is sealed under reduced pressure and the outer jacket materials facing each other around the core material are thermally welded to each other. A vacuum heat insulating container having a vacuum layer in the wall is used for the inner container, and low density polyethylene is used for the heat welding layer.

  As a result, since the vacuum insulation container is used for the inner container, the temperature outside the inner container when using the jar pot is lower than that of the inner container not using the vacuum insulation container. Even if low density polyethylene is used for the material, the temperature of the jacket material when using the jar pot is lower than the temperature at which the low density polyethylene melts. By using low density polyethylene, polypropylene and high density polyethylene can be used. Compared with the case of using, the mechanical strength such as pinhole resistance, heat seal strength, tensile / impact strength of the laminate film is further improved.

  Therefore, the quality of the vacuum heat insulating material is further improved, and the productivity of the jar pot can be further improved.

  In addition to the invention of claim 1, the invention of the vacuum heat insulating material according to claim 2 further includes a portion where the facing jacket materials around the core material in the vacuum heat insulating material are thermally welded. It was bent outside the inner container.

  The part of the vacuum insulation material where the outer cover materials around the core material are heat-welded is folded to the outside of the inner container, so that when the jar pot is used, it is not bent to the outside of the inner container. Since the temperature of the portion where the workpieces are heat-welded is lowered, the temperature of the portion where the jacket materials are heat-welded is lower than the temperature at which the low-density polyethylene melts, and low-density polyethylene is used. Thus, compared to polypropylene and high-density polyethylene, the mechanical strength such as pinhole resistance, heat seal strength, tensile / impact strength of the laminate film is further improved.

  Therefore, the quality of the vacuum heat insulating material is further improved, and the productivity of the jar pot can be further improved.

  Further, the invention of the vacuum heat insulating material according to claim 3 is the invention according to claim 1 or 2, wherein the vapor barrier film is used for the gas barrier layer of the jacket material positioned between the core material and the inner container. It was.

  As a result, heat leak from the inner container is reduced, the temperature of the heat-welded portion of the outer jacket material is lowered, and even when low-density polyethylene is used for the outer jacket material of the vacuum heat insulating material, the temperature does not melt further. Compared with polypropylene and high-density polyethylene, the use of low-density polyethylene further improves the mechanical strength such as pinhole resistance, heat seal strength, and tensile / impact strength of the laminate film.

  Therefore, the quality of the vacuum heat insulating material is further improved, and the productivity of the jar pot can be further improved.

  Hereinafter, embodiments of a jar pot according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view of a jar pot according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the jar pot of the present embodiment includes an outer case 1, a bottomed cylindrical inner container 2 that is disposed inside the outer case 1 and stores hot water, and an upper surface of at least a part of the outer case 1. And a cover covering the upper surface opening of the inner container 2 and an outer cover material having a heat-welding layer on the inner surface, the core material is sealed under reduced pressure, and the opposing outer cover materials around the core material are thermally welded to each other. 2 and a vacuum heat insulating material 3 disposed between the outer case 1, a vacuum heat insulating container having a vacuum layer in the wall for the inner container 2, and low density polyethylene for the heat welding layer. It is what was used.

  Here, the vacuum heat insulating container has a double structure of an inner layer and an outer layer, and is a so-called thermos in which a vacuum-depressurized space is provided between the inner layer and the outer layer. The material is mainly stainless steel.

  FIG. 2 is a perspective view of a vacuum heat insulating material used in the jar pot of the same embodiment.

  As shown in FIG. 2, the vacuum heat insulating material 3 used in the jar pot of the present embodiment is processed into a cylindrical shape so that the flat vacuum heat insulating material 3 can be wound so as to cover the outer peripheral surface of the inner container 2. It is a thing. Note that the joints are joined together with an adhesive tape or an adhesive. The material of the tape and the adhesive is not particularly limited as long as it can be joined and can maintain a cylindrical shape.

  In the present embodiment, the portion of the vacuum heat insulating material 3 where the outer jacket materials facing each other around the core material are heat-welded is bent to the outside of the inner container 2. Thereby, the temperature of the heat-welded portion of the outer cover material is lowered by folding the heat-welded portion of the outer cover material to the outside of the inner container.

  Actually, with the jar pot of the present embodiment, when the temperature of the heat-welded portion of the jacket material was measured at a water volume of 3 L, an initial water temperature of 20 ° C., a warm water temperature of 90 ° C., and an ambient temperature of 20 ° C., All locations were below 65 ° C.

  The vacuum heat insulating material 3 is composed of at least a core material and a jacket material. The core material is not particularly limited, such as inorganic fiber systems such as glass fibers and rock wool, organic fiber systems such as polyester fibers, and powder systems such as silica.

  The jacket material is a laminated film composed of a plurality of films. In this embodiment, low-density polyethylene is used for the heat-welded layer of the jacket material.

  Here, the structure of the laminate film used for the above-described temperature measurement is that the nylon film (thickness: 25 μm), nylon film (thickness: 15 μm), aluminum foil (thickness: 6 μm), straight chain on both sides A low-density polyethylene film (thickness: 50 μm).

  The continuous heat resistant temperature limit of linear low density polyethylene is 95 ° C to 100 ° C, and the continuous heat resistant temperature limit is 130 ° C of polypropylene and the continuous heat resistant temperature limit of 110 ° C of high density polyethylene. Has low characteristics.

  Table 1 shows the characteristics of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), metallocene-catalyzed linear low-density polyethylene film (mLLDPE), high-density polyethylene (HDPE), and polypropylene (CPP). Show the difference.

As can be seen from (Table 1), the distinction between low density polyethylene and high density polyethylene can be made by density. That is, if the density is higher than 940 kg / m ³ , it is a high-density polyethylene, and if the density is lower than 940 kg / m ³ , it is a variety of low-density polyethylene.

  However, if the determination of linear low density polyethylene and high density polyethylene cannot be made by density, the determination can be made by examining the melting point.

  Furthermore, low-density polyethylene has characteristics such as pinhole resistance, heat seal strength, and mechanical strength such as tensile / impact strength of the laminate film compared to polypropylene and high-density polyethylene.

  Therefore, as described above, the portion of the vacuum heat insulating material 3 around which the outer cover material around the core material is heat-welded is bent to the outside of the inner container 2 so that the outer cover material is heat-welded. Therefore, even if low density polyethylene is used in this embodiment, continuous heat resistance can be maintained.

  In this embodiment, the linear low-density polyethylene film is used. However, a normal low-density polyethylene film, a metallocene catalyst-based linear low-density polyethylene film, a normal low-density polyethylene, and a linear low-density polyethylene are used. It can also be applied to coextruded films made by extruding two or more different materials or having the same materials.

  As a result, even if low density polyethylene is used as the outer sheath material of the vacuum heat insulating material 3, it becomes a temperature that does not melt further, and by using low density polyethylene compared to polypropylene or high density polyethylene, the pin resistance of the laminate film Mechanical strength such as hole properties, heat seal strength, tensile / impact strength, etc. is further improved.

  The other laminate configuration is not particularly limited, but is a film having a metal foil such as nylon, polyethylene terephthalate, and aluminum foil, or a metal or non-oxide deposited film other than aluminum.

  Here, the film having a vapor deposition film is not particularly limited, for example, a film obtained by vapor deposition on a polyethylene vinyl alcohol copolymer film, a film obtained by vapor deposition on a polyethylene terephthalate film, and further, Some have a coating material on the surface of the deposited film.

  Further, in the present embodiment, a vapor deposition film is used for the gas barrier layer of the jacket material positioned between the core material and the inner container.

  Actually, with the jar pot of the present embodiment, when the temperature of the heat-welded portion of the jacket material was measured at a water volume of 3 L, an initial water temperature of 20 ° C., a warm water temperature of 90 ° C., and an ambient temperature of 20 ° C., the core material and In a form in which a vapor deposition film (film having a vapor deposition film) was used for the gas barrier layer of the jacket material positioned between the inner container 2 and the circumference, all the portions of the circumference were 60 ° C. or lower.

  Here, the configuration of the laminate film used for temperature measurement was that the inner container side had a nylon film (thickness: 25 μm) from the outermost layer, a polyethylene terephthalate film (thickness: 12 μm) having a deposited film, and a deposited film. A polyethylene vinyl alcohol copolymer film (thickness: 12 μm) and a low density polyethylene film (thickness: 50 μm).

  Further, the outer case side is nylon film (thickness: 25 μm), nylon film (thickness: 15 μm), aluminum foil (thickness: 6 μm), and low-density polyethylene film (thickness: 50 μm) from the outermost layer.

  This time, the temperature is lower than the temperature measurement described above, because the vapor barrier film (film with a vapor deposition film) is applied to the gas barrier layer of the jacket material located between the core material and the inner container 2. This is because heat leakage from the inner container 2 is reduced and the temperature of the heat-welded portion of the jacket material is lowered.

  Thereby, even if it uses low density polyethylene for the jacket material of the vacuum heat insulating material 3, it becomes the temperature which can maintain more continuous heat resistance.

  Therefore, low density polyethylene can be used, and mechanical strength such as pinhole resistance, heat seal strength, and tensile / impact strength of the laminate film is further improved as compared with polypropylene and high density polyethylene.

  Therefore, the mechanical strength such as pinhole resistance and tensile / impact strength of the laminate film is further improved, so that the possibility that the glass fiber pierces the laminate film from the inside and generates pinholes can be reduced.

  Moreover, when a laminated film is made by using low density polyethylene, the heat seal temperature is lowered, and the stability of heat seal at low temperature is improved, so that the heat seal strength can be stabilized.

  As described above, the jar pot of the present embodiment includes the outer case 1, the bottomed cylindrical inner container 2 that is disposed inside the outer case 1 and stores hot water, and the upper surface of at least a part of the outer case 1. The inner container 2 is formed by sealing the core material under reduced pressure with a cover covering the upper surface opening of the inner container 2 and the inner surface of the inner container 2 having a heat-welded layer, and the opposing outer jacket materials around the core material are thermally welded together. And a vacuum heat insulating material 3 disposed between the outer case 1 and the inner container 2 using a vacuum heat insulating container having a vacuum layer in the wall, and using a low density polyethylene for the heat welding layer. The gas barrier layer of the jacket material located between the core material and the inner container is formed by bending a portion of the vacuum heat insulating material 3 around the core material where the outer jacket materials facing each other are thermally welded to each other. A vapor deposition film is used.

  In the present embodiment, since the vacuum insulation container is used for the inner container 2, the temperature outside the inner container 2 when using the jar pot is lower than in the case of the inner container 2 not using the vacuum insulation container. Even if low density polyethylene is used for the jacket material of the vacuum heat insulating material 3, the temperature of the jacket material when using the jar pot is lower than the temperature at which the low density polyethylene is melted. Compared with the case of using polypropylene or high-density polyethylene, the mechanical strength such as pinhole resistance, heat seal strength, tensile / impact strength of the laminate film is further improved.

  In addition, when a portion of the vacuum heat insulating material around the core material where the outer cover materials facing each other are heat-welded is bent to the outside of the inner container 2, when the jar pot is used, it is not bent to the outer side of the inner container 2. Since the temperature of the portion where the jacket materials are heat-welded becomes lower than that, the temperature of the portion where the jacket materials are heat-welded becomes lower than the temperature at which the low density polyethylene melts.

  Further, by using a vapor deposition film for the gas barrier layer of the outer jacket material positioned between the core material and the inner container 2, heat leak from the inner container 2 is reduced, so that the heat-welded portion of the outer jacket material The temperature becomes lower.

  Therefore, the quality of the vacuum heat insulating material 3 further increases, and the productivity of the jar pot can be further improved.

(Examples and Comparative Examples)
In producing the vacuum heat insulating material, the core material was made of glass fiber, and the size of the core material when the vacuum heat insulating material was completed was 200 × 650 × 8 mm.

  As for the structure of the laminate film of the jacket material, the outer side at the time of cylinder processing is from the outermost layer to the nylon film (thickness: 25 μm), nylon film (thickness: 15 μm), aluminum foil (thickness: 6 μm), and each thermal welding It is a layer film (thickness: 50 μm).

  Also, the inner side during cylindrical processing is a nylon film (thickness: 25 μm) from the outermost layer, a polyethylene terephthalate film (thickness: 12 μm) having a vapor deposition film, and a polyethylene vinyl alcohol copolymer film (thickness) having a vapor deposition film. : 12 μm), and each heat welding layer film (thickness: 50 μm).

  With the structure of the vacuum heat insulating material described above, vacuuming was performed until the chamber vacuum degree of the vacuum packaging machine became 0.01 Torr, and a flat vacuum heat insulating material was produced.

(Number of pinholes after cylindrical machining)
As shown in FIG. 2, after processing the flat vacuum heat insulating material into a cylindrical shape, the outer cover material was broken, and the number of pinholes on both inner and outer sides was measured. In addition, the pinhole number measured the total number of both surfaces with the pinhole checker (Sanko Electronics make pinhole detector TRC-220A). Here, the N number was 10, and the average was taken.

  However, the measured pinhole includes a pseudo pinhole that does not completely penetrate the laminate film due to the measurement principle of the pinhole checker.

(Control temperature range)
The range within which the heat seal strength is 25 N or more and the heat seal temperature can be set so that the heat welded portion does not burn or air bite was examined. The heat seal temperature setting was changed in 5 ° C increments from the central value of the melting point of each material.

  The heat seal strength was measured with a small table tester EZTest manufactured by Shimadzu Corporation. Here, the number of N at each temperature setting is 10, the total number is 25 N or more, and the heat seal strength is such that no burning or air biting occurs, and the difference between the maximum temperature setting and the minimum temperature setting is taken. It was.

(Heat seal strength variation)
After the laminated film was made with a heat seal width of 10 mm, the heat seal strength at a heat welding length of 15 mm was measured. The heat seal strength was measured with a small table tester EZTest manufactured by Shimadzu Corporation. Here, the N number was 10, and the difference between the maximum value and the minimum value was taken.

  The results under the above conditions are shown in (Table 2).

  As described above, the jar pot according to the present invention can further improve the quality of the vacuum heat insulating material and improve the productivity of the jar pot, and has a heat insulating material between the outer case and the inner container. Applicable to heat insulation containers.

Schematic sectional view of a jar pot according to Embodiment 1 of the present invention The perspective view of the vacuum heat insulating material used for the jar pot of the embodiment

Explanation of symbols

1 Outer case 2 Inner container 3 Vacuum insulation

Claims (3)

  An outer case, a bottomed cylindrical inner container for storing hot water disposed inside the outer case, and a jacket material having a heat-welded layer on the inner surface is sealed under reduced pressure to oppose the periphery of the core material A jar pot comprising a vacuum heat insulating material disposed between the inner container and the outer case, wherein the outer jacket materials are thermally welded to each other, wherein the inner container has a vacuum layer in the wall. A jar pot using low-density polyethylene for the heat-welded layer.   The jar pot according to claim 1, wherein a portion of the vacuum heat insulating material around the core material where the facing outer cover materials are heat-welded is bent to the outside of the inner container.   The jar pot according to claim 1 or 2, wherein a vapor deposition film is used for a gas barrier layer of a jacket material positioned between the core material and the inner container.

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