JP2008050020A - Synthetic resin insulating container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic resin insulating container having a double structure which reduces heat loss at a joining section between an inner container and an outer container, and eliminates the breakage of the container due to wear between a gas-permeable porous body and an inner and outer wall surfaces to prevent a deterioration in gas barrier property. <P>SOLUTION: An insulating tank 21 is composed of the insulating container 22 and a lid 23. The insulating container 22 is composed of the synthetic resin inner container 24 and the synthetic resin outer container 25, the inner container 24 is placed in the outer container 25 via a gap 26. The outer surface of the synthetic resin inner container 24 and the inner surface of the synthetic resin outer container 25 excluding the joining section between the inner container 24 and the outer container 25 are coated with a DLC coat layer 34 by plasma CVD. The gap 26 is filled with the gas-permeable porous body 27 and is reduced in pressure, and the mouth of the inner container 24 and that of the outer container 25 are welded together. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat insulating container made of synthetic resin having a high degree of design freedom among heat insulating containers such as a heat insulating hot water tank, a thermos bottle, and a heat insulation lunch box.

  Conventionally, heat insulation containers such as heat insulation hot water tanks, thermos bottles, heat insulation lunch boxes, etc. have mainly used stainless steel double structure vacuum containers, but there is a problem of large heat leaks at metal joints, In order to suppress the convection of the residual gas, a high degree of vacuum was required, and it took time to evacuate.

  In addition, it is difficult to perform deep drawing in press working, and there is a limit to the degree of freedom in design, so that circular shapes are mainly used, and metal is heavy and not suitable for portable use.

  In addition, even if the vacuum vessel is composed of a synthetic resin double structure with a high degree of design freedom and a relatively low thermal conductivity, the oxygen and nitrogen gas permeation in the air is large and the water vapor permeation is large. Therefore, the degree of vacuum decreased with time, and there was a problem in long-term reliability of heat insulation performance.

  As a container that increases the degree of freedom in design and maintains heat insulation performance, a synthetic resin vacuum container such as Patent Document 1 has been introduced.

  This synthetic resin vacuum container is a vacuum container having a required vacuum degree between the outer bottle and the inner bottle, which consists of a double container body having gas barrier properties by molding, and has a pressure resistance of the outer bottle. A large-diameter air outlet is opened at the bottom, and the stopper lid that closes the outlet is permanently fixed through the conductive high-frequency induction short ring remaining between them, and at least the outer surface of the inner bottle is made of synthetic resin This is a synthetic resin vacuum vessel provided with a film and further provided with a reflective film formed by vapor deposition of aluminum on both bottles.

  Such a vacuum container needs to maintain a high vacuum of 1 Pa or less in order to suppress heat transfer due to convection of residual gas, and the heat insulation performance of the container is not only from the initial residual gas amount but also from the inner and outer bottle walls in practical use. It will be significantly affected by the permeating gas.

  Therefore, the restrictions on the degree of vacuum during the work of welding the lid that closes the discharge port with high frequency becomes strict, and even if a highly transparent acrylic synthetic resin film or a reflective film by aluminum deposition is provided, adhesion with aluminum deposition It is difficult to secure a thickness of 1 μm or more due to the problem of the property, and since there are many pinholes, it is difficult to maintain the gas barrier property for a long period of time. There is a problem that decreases.

As a method for solving this problem and maintaining the heat insulation performance, as shown in Patent Document 2, a container having a double wall structure in which an inner container is connected to an outer container with a gap in the mouth, The gap between the inner container and the outer container is filled with a breathable porous material at a packing density of 0.1 to 0.4 g / cm ³ and kept under reduced pressure. There is an introduction of heat insulating containers filled with water-absorbing adsorbents such as zeolite, calcium chloride, calcium carbonate, and anhydrous phosphoric acid.

  Examples of the air-permeable porous material include pearlite, synthetic silica, diatomaceous earth, shirasu balloon, calcium silicate, and the like. When the air gap is filled with these air-permeable porous materials, the gap becomes small and gas convection is suppressed. It is no longer necessary to secure a high degree of vacuum, making it very easy to manufacture vacuum containers, and the inner container is fixed to the outer container with a breathable porous material, which is resistant to shock and vibration, and changes over time The deterioration of the heat insulation performance due to is also suppressed.

  However, in a tank that stores hot water etc. like a jar pot, the conditions are severe, even if moisture penetrates through the wall and moisture enters the inside, the degree of vacuum becomes worse and a breathable porous body is inserted, Even if the adsorbent is filled, the heat insulation performance deteriorates with time.

  Further, FIG. 6 shows a conventional synthetic resin heat insulating container shown in Patent Document 3. A conventional synthetic resin insulated container will be described with reference to FIG.

  The heat insulating container 1 is composed of a container main body 2 and a lid 3, and the container main body 2 is composed of an inner container 4 and an outer container 5, and an outer container 5 having a larger dimension is put on the outer side of the inner container 4. It has a double wall structure with each mouth joined together. In the gap between the inner container 4 and the outer container 5, a heat insulating layer 6 formed by sealing a low thermal conductivity gas is formed.

  The inner container 4 and the outer container 5 are made of a synthetic resin material such as heat-resistant ABS resin, polypropylene, polycarbonate, polyacetal, polyethylene terephthalate, and polyethylene naphthalate.

  The outer container 5 has a bottomed cylindrical shape, and the upper end portion on the opening side is enlarged in diameter to form a stepped portion 8. An exhaust hole 10 is formed at the center of the bottom of the outer container 5, and the exhaust hole 10 is closed by a sealing plate 11. The inner container 4 has a bottomed cylindrical shape, and an upper portion of the inner container 4 is formed so as to contact the inner periphery of the outer container 5, and a flange 12 is formed at the upper end of the expanded diameter portion 9. .

  The flange 12 of the inner container 4 has a diameter that can be inserted into the step portion 8 of the outer container 5. The flange 12 of the inner container 4 is inserted into the step portion 8 of the outer container 5, and the lower surface of the flange 12 and the upper surface of the step portion 8 are welded and joined by a heat welding method such as an ultrasonic welding method or a high frequency induction heating welding method. A junction 15 is formed.

  Out of the outer peripheral surface of the inner container 4, the body portion and the bottom outer surface excluding the joint portion 16 in contact with the inner peripheral surface of the outer container 5, and the inner surface of the outer container 5 except for the joint portion 16, Is formed with a plating layer 14 made of a metal such as copper, silver, aluminum, nickel, or chromium.

  The thickness of the plating layer 14 is about 2 to 15 μm, preferably about 10 μm. If the thickness of the plating layer 14 is smaller than 2 μm, the effect of improving the gas barrier property by the plating layer 14 cannot be sufficiently obtained, and the gas with low thermal conductivity in the heat insulating layer 6 is lost and excellent heat insulation is achieved over a long period of time. The performance cannot be maintained. On the other hand, if the thickness of the plating layer 14 is larger than 15 μm, heat conduction from the inner container 4 side to the outer container 5 side through the plating layer 14 increases, and the heat insulating performance is deteriorated.

  As the gas sealed in the heat insulating layer 6, xenon, krypton, argon, or a mixed gas thereof, which is an inert gas with low thermal conductivity, is used. These xenon gas, krypton gas, and argon gas are particularly suitable because of their low thermal conductivity and no problem in environmental conservation due to their use.

The thickness 7 of the heat insulating layer 6 enclosing this low thermal conductivity gas is about 3 to 10 mm. When the thickness 7 of the heat insulating layer 6 exceeds 10 mm, the heat transfer loss due to the heat conduction of the gas becomes small, but a convective heat transfer loss occurs. By setting the thickness 7 of the heat insulating layer 6 to 3 to 10 mm, gas convection can be prevented and the heat insulating performance is improved.
Japanese Examined Patent Publication No. 63-43087 JP-A-2-265513 Japanese Patent No. 3009832

  However, the conventional synthetic resin heat insulating container of Patent Document 3 has a thickness of about 10 μm on the outer surface of the inner container and the inner surface of the outer container in order to improve the gas barrier property to the space between the inner and outer containers, and is made of copper, silver, aluminum. A plating layer made of a metal such as nickel or chromium is formed, and in particular, heat loss due to a short circuit at the mouth joint portion where the metal plating layer with extremely high thermal conductivity between the inner container 4 and the outer container 5 tends to be continuous is Become big.

  In addition, by forming a heat insulation layer filled with low thermal conductivity gas such as xenon, krypton, argon, etc. in the gap between the inner container and outer container, heat insulation performance by replacing the enclosed gas and air without requiring high vacuum Although there is little change, the heat insulation performance by convection is large, so the initial heat insulation performance is worse than that of vacuum heat insulation.

  In addition, in order to suppress heat transfer by convection, a method of filling a porous material having air permeability such as pearlite, synthetic silica, diatomaceous earth, shirasu balloon, calcium silicate, glass fiber, etc. can be considered, but the filler is not fixed. For this reason, the filler swells in the gap for each external vibration or impact, and slides on the surface of the metal plating layer having a relatively high coefficient of friction formed on the outer surface of the inner container and the inner surface of the outer container. There was a problem that the metal barrier surface was destroyed and the gas barrier property was lowered due to roughening and abrasion.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat insulating container made of a synthetic resin having excellent heat insulating performance, long-term reliability, and excellent volume efficiency.

  In order to achieve the above object, the synthetic resin heat insulating container of the present invention is arranged by placing a synthetic resin inner container with a gap in a synthetic resin outer container, and a joint between the inner container and the outer container. A DLC coating layer is provided by plasma CVD on the surface of the inner and outer containers made of synthetic resin, or DLC is formed by plasma CVD on the outer surface of the inner and outer containers made of synthetic resin excluding the joint portion between the inner container and the outer container. A coating layer is provided, the void is filled with a breathable porous body, the inside of the void is decompressed, and the respective mouths of the inner container and the outer container are welded and joined.

  Here, plasma CVD is Plasma Enhanced Chemical Vapor Deposition, and DLC is Diamond Like Carbon (Diamond Like Carbon). Further, the DLC coating layer may be a DLC coating layer containing fluorine.

  As a result, a space between the inner container and the outer container is filled with an air-permeable porous body to form a heat-insulating layer that has been depressurized. This reduces the gap and maintains low heat transfer performance due to convection without securing a high degree of vacuum. In addition, since the DLC coat layer having a low thermal conductivity or the DLC coat layer containing fluorine is provided by plasma CVD on the surfaces of the inner container and the outer container excluding the joint portion between the inner container and the outer container, the heat insulation performance is improved. Compared to conventional metal plating layers, DLC coating has no toxicity such as heavy metals, and there is no problem even if it is used as a wall surface that comes into contact with water or food. It becomes a layer with high property and denseness, high strength, and high gas barrier properties. In particular, the DLC coating layer by plasma CVD with high surface hardness and low coefficient of friction acts as a protective film on the outer side of the inner container and the inner side of the outer container in contact with the breathable porous body, and the filler is vibrated by vibration from the outside. Even if it repeats, a DLC coat surface is not worn and destroyed.

  In the synthetic resin heat insulating container of the present invention, an inner container made of synthetic resin is arranged in a synthetic resin outer container while maintaining a gap, and the mouths of these inner container and outer container are joined and integrated. In addition, a synthetic resin heat insulation container with a double wall structure in which a space between the inner container and the outer container is filled with a breathable porous body and a reduced heat insulation layer is formed, and a joint portion between the inner container and the outer container is formed. A DLC coating layer or a DLC coating layer containing fluorine is provided on the surfaces of the inner container and the outer container by plasma CVD, and the synthetic resins of the inner container mouth and the outer container mouth are welded and joined together. Since the heat-insulating layer was formed by filling the air gap between the inner container and the outer container with a breathable porous body and reducing the pressure, heat transfer due to convection is low even if the air gap is small and high vacuum is not maintained, and high heat insulating performance is achieved. It can be secured for a long time.

  In addition, a DLC coat layer containing water resistant plasma CVD or a DLC coat layer containing fluorine is a compound mainly composed of carbon, and has adhesion, denseness, and strength as compared with a layer formed by vapor deposition. In addition to high gas barrier properties, there is no problem even if it is used in contact with water or food, so there is no problem even if it is used in a food container such as a thermos or a lunch box.

  In addition, since a DLC coat layer having low thermal conductivity or a DLC coat layer containing fluorine is provided by plasma CVD on the outer surface of the inner container and the inner surface of the outer container excluding the joint portion between the inner container and the outer container, a short circuit of the coat layer The heat leak is kept small, and the deterioration of the heat insulation performance is suppressed. Furthermore, DLC by plasma CVD has a high surface hardness and a low coefficient of friction, so it has good wear resistance, and even if the filler repeatedly vibrates due to external vibration, the DLC coated surface will not be roughened and worn and destroyed, Thermal insulation performance can be maintained over the entire range. Therefore, the present invention provides a heat insulating container made of a synthetic resin having excellent heat insulating performance, long-term reliability, high design freedom and excellent volumetric efficiency.

  According to the first aspect of the present invention, the synthetic resin inner container is disposed in a synthetic resin outer container while maintaining a gap, and the synthetic resin inner and outer container surfaces excluding the joint portion between the inner container and the outer container are provided. A DLC coating layer is provided by plasma CVD, the air gap is filled with a gas-permeable porous body, the inside of the air gap is reduced in pressure, and the mouths of the inner container and the outer container are welded to each other. Since the heat-insulating layer is formed by filling the air gap between the container and the outer container with a breathable porous body and reducing the pressure, the heat transfer performance by convection is kept low even if the air gap is small and a high degree of vacuum is not secured. Since the DLC coating layer with low thermal conductivity is provided by plasma CVD on the surface of the inner container and the outer container excluding the joint part between the inner container and the outer container, the heat insulation performance is improved compared to the metal plating layer. DLC by plasma CVD can be used for conventional deposition Base and has adhesiveness, has denseness, problems in food hygiene by heavy metals as compared with the metal plating even without, it is possible to use the wall of the container in contact with water or food.

  According to a second aspect of the present invention, the synthetic resin inner container is disposed in a synthetic resin outer container while maintaining a gap, and the outer surface of the inner wall made of the synthetic resin excluding a joint portion between the inner container and the outer container. A DLC coating layer is provided by plasma CVD on the inner surface of the outer container, the air-permeable porous body is filled in the gap, and the inside of the gap is decompressed, and the respective mouths of the inner container and the outer container are welded to each other. Since the heat-insulating layer is formed by filling the air gap between the inner container and the outer container with a breathable porous body and reducing the pressure, the heat transfer performance by convection is kept low even if the air gap is small and high vacuum is not secured. The DLC coating layer with high surface hardness and low friction coefficient is provided on the outer surface of the inner container and the inner surface of the outer container that can ensure high heat insulation performance. Even if the filler repeatedly vibrates, the DLC coated surface is roughened and worn. Since not be allowed destroyed, in which heat insulating performance is maintained over time.

  In the invention according to claim 3, the DLC coat layer provided by plasma CVD in the invention according to claim 1 or 2 is a DLC coat layer containing fluorine, and fluorine is contained in addition to carbon in the plasma CVD process. The DLC coating layer containing fluorine formed by injecting a predetermined amount of gas improves the denseness and flexibility of the DLC coating layer and prevents cracking during work and use. Further, the present invention provides a further enhanced heat insulating container made of synthetic resin.

  Hereinafter, embodiments of 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 synthetic resin heat insulating container according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part showing a joint portion of the synthetic resin heat insulating container according to Embodiment 1. FIG. 3 is a schematic longitudinal sectional view of a plasma ion implantation film forming apparatus for performing DLC coating by plasma CVD on the inner and outer containers of the synthetic resin heat insulating container according to the first embodiment. FIG. 5 is a diagram showing a change in the plasma sheath in the vicinity of the product to be processed when a high voltage pulse is applied in the first embodiment, and FIG. 5 is a schematic cross-sectional view showing the bonding process of the synthetic resin heat insulating container in the first embodiment It is.

  In FIG. 1, the heat insulation tank 21 is composed of a heat insulation container 22 and a lid 23, and the heat insulation container 22 is composed of an inner container 24 and an outer container 25. A double wall structure is formed by covering the container 25 and integrally joining the respective mouths.

  The space 26 between the inner container 24 and the outer container 25 has a double wall structure in which a heat-insulating layer 28 filled with a permeable porous body 27 and decompressed is formed. Is made of a synthetic resin material such as heat-resistant ABS resin, polypropylene, polycarbonate, polyacetal, polyethylene terephthalate, polyethylene naphthalate, modified PPE, or modified PPS.

  Further, an enlarged diameter portion 30 is formed at the upper portion of the inner container 24 so as to contact the flange 29 of the outer container 25. The enlarged diameter portion 30 of the inner container 24 has the same size as the outer periphery of the flange 29 of the outer container 25, and the surface of the inner diameter of the inner container 24 that contacts the outer container 25 flange 29 becomes a joint portion 31, which is joined by infrared laser welding. Has been.

  FIG. 2 is an enlarged cross-sectional view of the main part of the enlarged diameter portion 30 of the inner container 24 and the flange 29 of the outer container 25 before joining, but the surface of the enlarged diameter portion 30 of the inner container 24 is in contact with the flange 29 of the outer container 25. Protrusions 32 for condensing the laser are provided on the entire circumference.

  The outer surface of the inner container 24 excluding the joint portion 31 with the surface of the flange 25 of the outer container 25 and the inner surface of the outer container 25 except for the joint portion 31 include fluorine provided by plasma CVD. A DLC coating layer 34 is formed.

  The thickness of the DLC coating layer 34 containing fluorine provided by plasma CVD is in the range of 0.1 to 20 μm, preferably about 2 μm. If the thickness of the DLC coating layer 34 containing fluorine is smaller than 0.1 μm, pinholes and the like are developed, and the effect of improving the gas barrier property by the DLC coating layer 34 cannot be sufficiently obtained, and air is not contained in the heat insulating layer 28. Moisture permeates and enters, and the degree of vacuum is lost, making it impossible to maintain excellent heat insulation performance over a long period of time. On the other hand, when the thickness of the DLC coat layer 34 is larger than 20 μm, heat conduction from the portion where the DLC coat layer 34 is short-circuited to the outer container 25 side from the inner container 24 side increases, and the heat insulation performance is deteriorated. .

  In the center of the bottom of the outer container 25, an adsorbent 35 such as zeolite, calcium oxide or calcium chloride that absorbs moisture is installed.

  The breathable porous body 27 enclosed in the heat insulating layer 28 is filled with a porous material such as pearlite, synthetic silica, diatomaceous earth, shirasu balloon, calcium silicate, glass fiber, etc. In the first embodiment of the present invention. A composite powder molded body containing dry silica having an average primary particle diameter of 100 nm or less and an inorganic fiber material having an average fiber diameter of 10 μm or less is used.

  Although it is difficult to form a molded body by mixing and stirring with a general silica powder and a fiber material, the mixture is mixed with dry silica having an average primary particle diameter of 100 nm or less and an inorganic fiber material having an average fiber diameter of 10 μm or less. A strong molded body can be obtained by compression molding. The reason for this is that powders with small particle diameters work together because the intermolecular force works and powders adhere to each other, or because they are dry, the surface functional groups are few and the mutual repulsion is small, so the powders are easy to stick together, or silica and inorganic It is a good combination of fibers, so it is easy to adhere to each other, and since the fiber diameter of inorganic fibers is small, the specific surface area increases, that is, the surface energy increases and it becomes easy to bind to the powder, or their complex interaction I think that.

In Embodiment 1 of the present invention, a step of mixing dry silica and an inorganic fiber material, a step of putting this in a mold and press-molding with a pressure of 0.5 N / mm ² or more to obtain a composite powder molded body, The composite powder molded body is inserted between an outer container 25 and an inner container 24 having gas barrier properties, and the opening is sealed by infrared laser welding in a reduced pressure state of 1 Pa or less.

  It is desirable that the lid 23 attached above the heat insulating container 22 is hinged to the opening end of the heat insulating container 22 so that it can be opened and closed and has good heat insulating performance. The heat insulating structure of the lid 23 is not particularly limited, but the same heat insulating structure as the heat insulating container 22 is preferable.

  Next, the manufacturing method of this heat insulation container 22 is demonstrated.

  First, the inner container 24 and the outer container 25 are manufactured by an appropriate method such as an injection molding method. As shown in FIG. 2, the inner container 24 is provided with a protrusion 32 having a square cross section on the entire lower surface of the enlarged diameter portion 30. The shape of the protrusion 32 is not limited to this, and the cross section may be V-shaped or semicircular.

  Next, the vicinity of the joint 33 of the protrusion 32 on the outer peripheral lower surface of the enlarged diameter portion 30 of the inner container 24 that becomes the joint 33 of the inner container 24 and the outer container 25 and the vicinity of the joint 33 of the flange 29 of the outer container 25. Then, the fixing member is closely covered or masked by covering with an easily peelable adhesive or adhesive tape, and other exposed portions of the outer surface of the inner container 24 and the inner surface of the outer container 5 are DLC coated by the CVD method. Layer 34 is formed.

  Next, a method for forming the DLC coat layer 34 containing fluorine by this CVD method will be described in detail.

  FIG. 3 is a schematic longitudinal sectional view of a plasma ion implantation film forming apparatus using a three-dimensional ion implantation method used for manufacturing the heat insulating container 22 according to Embodiment 1 of the present invention.

  The plasma ion implantation film forming apparatus 51 of FIG. 3 is used to coat a three-dimensional object to be processed with a desired material. In the first embodiment, a case will be described in which the outer surface of the inner container 24 and the inner surface of the outer container 25 which are injection-molded with a PPS (polyphenylene sulfide) resin as a workpiece are coated.

This plasma ion implantation film forming apparatus 51 includes a chamber 52 to which an evacuation system 53 for exhausting an internal gas and a gas introduction system 54 for introducing a gas are connected. In the first embodiment, methane (CH ₄ ) and carbon tetrafluoride (CF ₄ ) are introduced into the chamber 52 by the gas introduction system 54.

  In the first embodiment, the inner surface of the inner container 24 and the inner surface of the outer container 25 are disposed upward in the chamber 52, and the inner surface of the inner container 24 and the outer surface of the outer container 25 are interposed via a jig 50 made of metal or the like. The conductor 55 is connected. The conductor 55 is drawn out of the chamber 52 through the highly insulated feedthrough 56 and connected to the superimposing device 57. An RF high frequency power source 58 and a high voltage pulse power source 59 are connected to the superimposing device 57. The voltage value of the high voltage pulse power supply 59 is, for example, 10 kV, and the pulse width is, for example, 2 μs. An arc-type metal plasma source 60 is connected in the chamber 52.

  The RF high frequency power source 58 generates RF power for generating plasma in the chamber 52. In the first embodiment, the RF high frequency power supply 58 generates pulsed RF power. The output frequency of the RF power is 13.56 MHz, the output power is variable, for example, from 0.5 kW to 1.5 kW, and the pulse width is variable, for example, 20 μs.

  The high voltage pulse power supply 59 generates a negative high voltage pulse for ion implantation and film formation. The voltage value of the high voltage pulse is variable from 0 to −50 kV, and the pulse width is variable from 2 μs.

  The superimposing device 57 applies the RF power generated by the RF high frequency power supply 58 and the high voltage pulse generated by the high voltage pulse power supply 59 to the jig 50 through the conductor 55 at the timing of alternately delaying or overlapping. Thereby, even when an insulating container is used as the object to be processed, the outer surface of the inner container 24 and the inner surface of the outer container 25 can be covered as described later.

  Next, the principle of coating the outer surface of the inner container 24 and the inner surface of the outer container 25 with a DLC thin film using the plasma ion implantation film forming apparatus of FIG. 3 will be described with reference to FIG. FIG. 4 is a diagram showing changes in the plasma sheath near the outer surface of the inner container 24 and the inner surface of the outer container 25 when a high voltage pulse is applied.

  A hydrocarbon gas is used as the gas introduced into the chamber 52. Here, a case where methane and carbon tetrafluoride are used as the gas introduced from the gas introduction system 54 will be described.

  First, the inner surface of the inner container 24 and the inner surface of the outer container 25 are arranged in the chamber 52 in a state of being connected to the conductor 55 via the jig 50, and the inside of the chamber 52 is evacuated by the vacuum exhaust system 53, and then the gas introduction system 54 Methane and carbon tetrafluoride are introduced into the chamber 52, and the inside of the chamber 52 is brought to a predetermined gas pressure. In this state, pulsed RF power is applied from the RF high frequency power source 58 to the outer surface of the inner container 24 and the inner surface of the outer container 25 through the superimposing device 57 and the conductor 55. Thereby, uniform plasma containing positive ions and electrons is generated around the outer surface of the inner container 24 and the inner surface of the outer container 25 along the shapes of the outer surface of the inner container 24 and the inner surface of the outer container 25.

  Thereafter, a negative high voltage pulse is applied from the high voltage pulse power source 59 to the outer surface of the inner container 24 and the inner surface of the outer container 25 through the superimposing device 57 and the conductor 55. As a result, positive ions in the plasma are attracted to the outer surface of the inner container 24 and the inner surface of the outer container 25.

  When a high voltage pulse is not applied to the outer surface of the inner container 24 and the inner surface of the outer container 25, the plasma is in a uniform state as shown in (1) of FIG. When a high voltage pulse is applied to the outer surface of the inner container 24 and the inner surface of the outer container 25, as shown in (2) of FIG. 4, the electrons in the plasma move away from the outer surface of the inner container 24 and the vicinity of the inner surface of the outer container 25, and positive ions are Almost no movement due to large mass. Thereby, only positive ions remain around the outer surface of the inner container 24 and the inner surface of the outer container 25, and a plasma sheath is formed.

  As shown in (3) of FIG. 4, when an electric field is strengthened after several μs has elapsed from the start of application of the high voltage pulse, positive ions are caused by the sheath voltage of the plasma sheath to cause the outer surface of the inner container 24 and the outer container 25 to be positive. Accelerated in the direction of the inner surface. When positive ions collide with the outer surface of the inner container 24 and the inner surface of the outer container 25, the balance of charges near the outer surface of the inner container 24 and the inner surface of the outer container 25 is lost, and as shown in FIG. And the thickness of the plasma sheath increases. In this way, ions are implanted into the outer surface of the inner container 24 and the inner surface of the outer container 25, and films are formed on the outer surface of the inner container 24 and the inner surface of the outer container 25.

  In this embodiment, since methane and carbon tetrafluoride are introduced as gases into the chamber 52, the plasma contains hydrocarbon positive ions, hydrogen positive ions, carbon positive ions, and fluorine positive ions. It is. As a result, DLC thin films are formed on the outer surface of the inner container 24 and the inner surface of the outer container 25.

  According to this plasma ion implantation film-forming apparatus 51, the outer surface of the inner container 24 and the inner surface of the outer container 25, which are the objects to be processed, are used as the antenna for generating plasma, thereby conforming to the shapes of the outer surface of the inner container 24 and the inner surface of the outer container 25 Plasma can be generated. As a result, the density of the plasma around the outer surface of the inner container 24 and the inner surface of the outer container 25 is inevitably increased, the efficiency of attracting ions is improved, and a DLC thin film having high adhesion can be formed.

  Here, the outer surface of the inner container 24 and the inner surface of the outer container 25 made of synthetic resin have insulation and flexibility. On the other hand, general DLC has high hardness and low friction and gas barrier properties, but on the other hand, it is easy to peel off and it is difficult to form a thick film. In particular, when a DLC thin film is formed on the surface of a synthetic resin having flexibility, the DLC thin film is easily peeled by deformation of the synthetic resin.

  In order to manufacture the heat insulating container 22 that can reliably seal air and water vapor over a long period of time, the outer surface of the inner container 24 made of synthetic resin and the inner surface of the outer container 25 have high hardness, wear resistance, and high gas barrier properties. It is necessary to form a DLC thin film having a predetermined thickness with high adhesion and flexibility.

  Next, with reference to FIG. 5, the structure of the vacuum welder 76 and the assembly process of the inner container 24 and the outer container 25 in which the DLC coat layer 34 containing fluorine is formed will be described.

  The vacuum welding machine 70 includes a vacuum chamber 72 having a vacuum pump 71 and a press machine 74 having a built-in diode 73 that emits an infrared laser. The press machine 74 includes an upper mold 75 and a lower mold 76. The upper die 75 fixes the inner container 24, and laser diodes 73 are arranged corresponding to the entire circumference of the enlarged diameter portion 30 of the inner container 24. The lower mold 76 can fix the flange portion 29 of the outer container 25.

  First, the outer container 25 is set in the lower mold 76, and a 10 mm thick composite powder molded body 77 formed by the method described above and cut to a predetermined size is temporarily placed on the bottom of the outer container 25 and the front, rear, left and right inner surfaces. Then, the absorbent 35 is set on the upper surface of the bottom composite powder molded body 77.

  Next, the upper mold 75 attached with the inner container 24 is set above the lower mold 76, and the upper mold is lowered to a position just before the lower surface of the enlarged diameter portion of the inner container 24 and the upper surface of the flange of the outer container 25 are in contact with each other. Then, the opening of the chamber 72 is closed and evacuation is started. After confirming that the degree of vacuum is 1 Pa or less with the vacuum gauge 78, the upper mold is lowered again, and the lower surface of the enlarged diameter portion 30 of the inner container 24 and the upper surface of the flange of the outer container 25 are pressure-bonded.

  Next, simultaneously with the pressure bonding, the laser diode is driven, and the protrusion on the upper surface of the outer container flange portion is welded to join the inner container and the outer container.

  At this time, the PPS resin used in the outer container is a mixture of absorbing dyes in order to absorb the laser light and generate heat appropriately.

  At this time, the protrusions 32 are mainly heated and melted, and the inner container 24 is pressed and spread as necessary to expand the protrusions 32, and the lower surface of the flange 29 portion of the inner container 24 and the upper surface of the enlarged diameter portion 29 of the outer container 55 And the inner container 24 and the outer container 25 are joined together.

  As a method for performing such welding, the Wei infrared laser welding method is used this time, but an ultrasonic welding method, a vibration welding method and the like are preferable. In this way, the inner container 24 and the outer container 25 are integrally joined by welding between the protrusion 32 provided on the enlarged diameter portion 30 and the flange protrusion 32 in contact with the protrusion 32. It is possible to perform reliable welding without causing thermal deformation of itself.

  Next, the movement of heat when hot water is stored in the heat insulating tank 21 configured as described above will be described.

  The heat in the heat insulation tank includes the inner container 24 wall surface, the air-permeable porous body 27 in the space in the decompressed state, the A path that passes through the wall surface of the outer container 25 and moves to the outside air, and the inner container 24 has an enlarged diameter. A B path that moves through the portion 30 and a C path that short-circuits the DLC coat 34 layer from the wall surface of the inner container 24 and moves to the wall surface of the outer container 25 are conceivable.

  First, in the A path, the heat insulating performance of the breathable porous body 27 in a reduced pressure state is important. In Embodiment 1 of the present invention, there is a breathable porous body 27 that prevents gas convection, and a 1 μm DLC coating process with low moisture permeability and high gas barrier properties is applied to the inner container 24 and the outer container 25. As a result, a decrease in the initial vacuum due to the introduction of gas into the gap 26 can be suppressed. In addition, since some moisture intrusion is trapped by the adsorbent, the initial vacuum can be ensured over a long period of time.

  Next, with respect to the B path, the resin has a thermal conductivity close to 1/50 as compared with a metal such as stainless steel, and the heat insulation performance is high. In the first embodiment of the present invention, the heat transfer is not large.

  As for the C path, the DLC coat layer has a thermal conductivity of 1/10 or less compared to the conventional metal plating, and the DLC coat by CVD is denser than the vapor deposition and requires the necessary transparency. Since the thickness can be reduced in order to ensure wettability and gas barrier properties, heat transfer is significantly reduced compared to the conventional case.

  Furthermore, the coefficient of friction of the DLC coating layer is very low compared to the metal plating layer, and the porous material. Because the filler is not fixed, the filler swells in the air gap due to external vibrations and shocks, roughens and wears the wall surface, eventually destroys the metal plating surface and lowers the gas barrier property. This problem can also be solved.

  In Embodiment 1 of the present invention, the DLC coating layer containing fluorine is provided by plasma CVD on the outer surface and inner surface of the inner container made of synthetic resin, but the outer surface and inner surface of the inner container and the outer container are on all surfaces. Even if a DLC coating layer containing fluorine is provided, the reliability can be further improved, and the present invention is not limited to the outer surface of the inner container and the inner surface of the outer container.

  Moreover, although the DLC coat layer containing fluorine was used, although it was inferior in flexibility, even the DLC coat layer not containing fluorine has low moisture permeability, good gas barrier properties, low friction coefficient, and contains fluorine It is not limited to.

  As described above, the synthetic resin heat insulation container according to the present invention is not only used as a heat insulation container such as a heat insulation hot water tank, a thermos bottle, and a heat insulation lunch box as in the prior art, but also has a merit of design freedom and a high gas barrier performance. Utilizing it, it can be stored in a small space, so it can be used as a heat storage tank and a heat insulation cover around the engine of a car, which is a durable consumer goods such as a refrigerator with a long service life.

Schematic sectional view of a synthetic resin heat insulating container according to Embodiment 1 of the present invention. The principal part expanded sectional view which shows the junction part of the synthetic resin heat insulation container in Embodiment 1 of this invention 1 is a schematic longitudinal sectional view of a plasma ion implantation film forming apparatus that performs DLC coating by plasma CVD on an inner container outer side and an outer container inner side of a synthetic resin heat insulating container in Embodiment 1 of the present invention. Schematic which shows the change of the plasma sheath of inner container outer surface at the time of applying the high voltage pulse in Embodiment 1 of this invention, and outer container inner surface vicinity Schematic sectional view showing the joining process of the synthetic resin heat insulating container in the first embodiment of the present invention Schematic cross-sectional view of a conventional synthetic resin insulated container

Explanation of symbols

22 Heat insulation container 24 Inner container 25 Outer container 26 Void 27 Breathable porous body 34 DLC coating layer

Claims (3)

  A synthetic resin inner container is placed in a synthetic resin outer container while maintaining a gap, and a DLC coating layer is provided by plasma CVD on the surface of the synthetic resin inner and outer containers excluding the joint between the inner container and the outer container. A synthetic resin heat insulating container, wherein the air gap is filled with a breathable porous body, the inside of the air gap is reduced in pressure, and the mouths of the inner container and the outer container are welded to each other.   An inner container made of synthetic resin is placed in a synthetic resin outer container with a gap, and plasma CVD is applied to the outer surface of the inner and outer containers made of synthetic resin excluding the joint between the inner container and the outer container. A synthetic resin, characterized in that a DLC coating layer is provided, the gap is filled with a porous porous body, the inside of the gap is decompressed, and the mouths of the inner and outer containers are welded to each other. Insulated container.   The heat insulating container made of synthetic resin according to claim 1 or 2, wherein the DLC coat layer provided by plasma CVD is a DLC coat layer containing fluorine.