Thermal insulation retaining laminate

Abstract

To provide a heat-insulating holding laminate for a vacuum heat-insulating panel outer packaging material, a heat-insulating holding packaging material, and a heat-insulating holding package which have a sealant layer having a small amount of gas discharge generated from the sealant layer itself, suppress rise in an atmospheric pressure in an internal depressurized condition inside a vacuum heat-insulating panel due to degradation with time, and suppress rise of thermal conductivity in a thickness direction of the vacuum heat-insulating panel.SOLUTION: A heat-insulating holding laminate 1 for a vacuum heat-insulating panel has a gas barrier base material layer 3 and a low gas dischargeable sealant layer 4, in which the low gas dischargeable sealant layer 4 contains a low gas dischargeable resin having heat sealability, and the low gas dischargeable resin has a density of 0.915 g / cm3 or more and 0.935 g / cm3 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a heat insulating retaining laminate for use in a vacuum insulation panel outer packaging material, the laminate having a sealant layer that generates a small amount of gas emission from the sealant layer itself. [Background technology]

[0002] A vacuum insulation panel has an internal structure with a core material sealed within an outer packaging material, and the pressure inside the vacuum insulation panel is much lower than atmospheric pressure, maintaining a reduced pressure state close to a vacuum. Since the inside of the vacuum insulation panel is in a reduced pressure state, which suppresses thermal convection, the vacuum insulation panel can exhibit good insulation performance in the thickness direction, and the insulation performance per unit thickness of the vacuum insulation panel is higher than that of general foam insulation materials. Furthermore, since the insulation efficiency is high, the vacuum insulation panel can be made thin while maintaining the desired insulation properties. Therefore, by using a vacuum insulation panel to manufacture an insulated container, it is possible to reduce the weight and space of the insulated container. However, if the vacuum insulation panel is damaged or deteriorates over time, causing the internal air pressure to rise and the reduced pressure state to be lost, the insulation performance of the panel will rapidly decrease. Conventionally, the reason for the increase in internal air pressure due to deterioration over time caused by the outer packaging material has been said to be the intrusion of air as it permeates the outer packaging material. In order to improve the gas barrier properties of the outer packaging material, laminated films having a metal aluminum foil with a thickness of about 7 to 15 μm as a gas barrier layer have been mainly used for the outer packaging material, and laminated films having an additional layer made of a vapor-deposited film or coating film of various inorganic materials have been proposed (Patent Document 1). However, these have been insufficient in terms of maintaining stable insulation properties over the long term. A method has been proposed in which a porous material such as synthetic zeolite is incorporated into the sealant layer of the packaging material to adsorb gas components and thereby maintain the degree of vacuum inside the package (Patent Document 2). However, this method is insufficient in terms of maintaining a stable insulation effect over the long term, due to the limited types of gases that can be adsorbed, the low heat resistance of the resin that constitutes the sealant layer, and the large amount of outgassing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-087176 A [Patent Document 2] JP 2018-189220 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a heat insulating laminate for use as an outer packaging material for a vacuum insulation panel, a heat insulating packaging material, and a vacuum insulation panel which have a sealant layer that generates a small amount of gas from the sealant layer itself, and which suppresses an increase in air pressure in the internal reduced pressure state inside the vacuum insulation panel due to deterioration over time, thereby suppressing an increase in thermal conductivity through the thickness of the vacuum insulation panel. [Means for solving the problem]

[0005] As a result of various investigations, the present inventors have found that the above object can be achieved by a heat insulating laminate which at least emits a small amount of gas. That is, the present invention is characterized in the following points. 1. A thermal insulation retaining laminate for a vacuum insulation panel, comprising: The heat insulating support laminate has a gas barrier substrate layer and a low gas release sealant layer, The low gas releasing sealant layer contains a low gas releasing resin having heat sealability, The low gas emission resin has a density of 0.915 g / cm3 More than 0.935g / cm 3 A heat insulating laminate, characterized in that: 2. The heat insulating retaining laminate described in 1 above, characterized in that the content of the low gas releasing resin in the entire low gas releasing sealant layer is 70 mass % or more and 99.9 mass % or less. 3. The heat insulating laminate according to 1 or 2 above, wherein the low gas releasing resin is a polyethylene resin. 4. A heat insulating laminate described in any one of claims 1 to 3, characterized in that the concentration of soluble total organic carbon (TOC) contained in the film made of the low gas release resin is 1.5 ppm or more and 250 ppm or less. 5. The heat insulating laminate described in any one of 1 to 4 above, characterized in that the low gas release resin is one or a combination of two or more selected from the group consisting of medium density polyethylene, low density polyethylene, and linear low density polyethylene. 6. The heat insulating laminate according to any one of the above items 1 to 5, wherein the low gas releasing sealant layer further contains an antioxidant. 7. The heat insulating laminate according to 5 above, characterized in that the content of the antioxidant in the entire low gas releasing sealant layer is 0.005 mass % or more and 0.5 mass % or less. 8. The heat insulating retaining laminate according to any one of the above items 1 to 7, wherein the low gas releasing sealant layer is a layer made of a low gas releasing sealant film. 9. The low gas emission sealant film has a carbon number of 16 organic gas component released when heated in air at 90°C for 60 minutes, and the amount of the low gas emission sealant film per unit volume of the low gas emission sealant film is 10 μg / cm 3 More than 1000μg / cm 3 9. The heat insulating laminate according to claim 8, characterized in that: 10. A heat insulating property-retaining packaging material for a vacuum insulation panel, produced using the heat insulating property-retaining laminate described in any one of 1 to 9 above. 11. A vacuum insulation panel produced using the heat insulating packaging material described in 10 above. Effect of the Invention

[0006] According to the present invention, it is possible to obtain a heat insulating laminate, a heat insulating packaging material, and a heat insulating packaging body for use as an outer packaging material for a vacuum insulation panel, which has a sealant layer that generates a small amount of gas from the sealant layer itself, and which suppresses an increase in air pressure in the internal reduced pressure state inside the vacuum insulation panel due to deterioration over time, thereby suppressing an increase in the thermal conductivity of the vacuum insulation panel through the thickness direction. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the heat insulating property-retaining laminate or heat insulating property-retaining packaging material of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing an example of another embodiment of the layer structure of the heat insulating property retaining laminate or heat insulating property retaining packaging material of the present invention. [Diagram 3] FIG. 2 is a schematic cross-sectional view showing another example of the layer structure of the heat insulating property retaining laminate or heat insulating property retaining packaging material of the present invention. [Figure 4] FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a heat insulating packaging body (vacuum insulation panel) of the present invention.

[0008] In each drawing, the size and ratio of the components may be changed or exaggerated for ease of understanding. Also, for ease of understanding, parts that are unnecessary for the explanation or repeated reference numerals may be omitted. Although not shown in the drawings, an adhesive layer may be provided between each layer. Furthermore, if necessary, in order to strengthen the adhesive strength (adhesion strength) between each layer, the laminated surfaces of each layer may be subjected to corona discharge treatment, ozone treatment, plasma treatment, glow discharge treatment, sandblasting, etc. Alternatively, the surface may be previously subjected to a physical surface treatment such as a thermal treatment or a chemical surface treatment such as an oxidation treatment using a chemical agent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The heat insulating laminate, the heat insulating packaging material, and the heat insulating packaging body of the present invention will be described in more detail below. Specific examples will be given, but the present invention is not limited thereto. In the present invention, the terms film and sheet are used synonymously.

[0010] <Thermal insulation retaining laminate> The heat insulating property-retaining laminate of the present invention is a laminate used as an outer packaging material for a vacuum insulation panel, and has a layer structure including a gas barrier substrate layer and a low gas releasing sealant layer. The low outgassing sealant layer contains a low outgassing resin, and the low outgassing resin is preferably a low outgassing resin having heat sealability.

[0011] Although depending on the application, the inside of the vacuum insulation panel is often reduced in pressure to 0.1 to 100 Pa. A vacuum insulation panel packaged with the heat insulation retaining laminate of the present invention maintains its internal reduced pressure state over a long period of time, thereby maintaining its insulation properties in the thickness direction. Regarding the insulation maintenance of the vacuum insulation panel, for example, the increase in thermal conductivity after storage for 1000 hours in an environment of 100° C. is preferably 0 mW / mK or more and 7.0 mW / mK or less, and more preferably 0 mW / mK or more and 6.5 mW / mK or less. It is most preferable that there is no increase in thermal conductivity, and those exceeding the above range are likely to be inferior in practical use over a long period of time.

[0012] In order to maintain a reduced pressure state inside the vacuum insulation panel, it is necessary to suppress the increase in gas molecules inside the vacuum insulation panel. To do this, it is necessary to suppress the amount of gas released from the outer packaging material of the vacuum insulation panel itself, the amount of gas that penetrates through the thickness of the outer packaging material and enters the inside of the vacuum insulation panel, and the amount of gas that penetrates into the inside of the vacuum insulation panel through the interface of the joints created by heat sealing the outer packaging material, etc.

[0013] Of the gas released from the outer packaging material itself into the interior of the vacuum insulation panel, a large amount is released from the sealant layer of the outer packaging material, and a heat seal layer is present at the interface of the joints of the outer packaging material, such as those formed by heat sealing, and a sealant layer is in contact with the internal space of the vacuum insulation panel. Therefore, the sealant layer of the heat insulation retaining laminate of the present invention is a low gas release sealant layer, which generates a small amount of gas by itself and has excellent heat sealing properties, thereby preventing gas that penetrates into the vacuum insulation panel through the joint interface from reaching the inside of the vacuum insulation panel, thereby preventing an increase in air pressure inside the vacuum insulation panel, maintaining a reduced pressure state, and maintaining insulation properties.

[0014] The gas release properties of the heat insulating retaining laminate of the present invention are dominated by the gas release properties of the low gas release sealant layer that constitutes the heat insulating retaining laminate, and can be determined by measuring the gas release properties of the low gas release sealant film that forms the low gas release sealant layer. For example, a low outgassing sealant film is cut into two strips of 50 mm x 10 mm, and these strips are placed in a test tube and heated at 90°C for 60 minutes. The air in the test tube is then sampled and the concentrations of organic gas components with each carbon number in the sampled air are measured by gas chromatography, from which the amount of organic gas components released by the low outgassing sealant film when heated can be calculated. Among organic gas components, the amount of C16 gas components (organic gas components with 16 carbon atoms) in particular is highly correlated with the thermal conductivity of vacuum insulation panels made using insulation-retaining packaging materials having a sealant layer formed from a low-gas-releasing sealant film.

[0015] The amount of C16 gas released when the low gas release sealant film is heated, as determined by the above method, per unit volume of the low gas release sealant film is 10 μg / cm 3 More than 1000μg / cm 3 It is preferable that:

[0016] (Gas released) The gas components released from the heat insulating laminate of the present invention are mainly gas components originally contained in the heat insulating laminate of the present invention (particularly the low gas release sealant layer), gas components consisting of resin decomposition products generated by decomposition of the resin in the heat insulating laminate by heating such as heat sealing or irradiation with UV or EB, etc., and gas components present in the atmosphere. Here, examples of gas components originally contained in the heat insulating laminate include gas components contained in the raw materials constituting the heat insulating laminate (particularly the low gas release sealant layer), gas components generated due to the thermal history when forming the heat insulating laminate, and gas components generated when the heat insulating laminate is heat sealed.

[0017] Specific examples of the gas components released include low molecular weight organic matter and carbon dioxide. Organic matter is a gas component derived from the heat insulating laminate, and the compounds of the gas components often have a carbon number of 1 to 16, and the most common type is hydrocarbons, but other examples include alcohols, aldehydes, ketones, and carboxylic acids.

[0018] Specific examples of hydrocarbon compounds include propane, propene, butane, isobutane, 2-methylbutane, butene, isobutene, 2-methylpentane, 3-ethylpentane, 2,2-dimethylpentane, 3,3-dimethylpentane, hexane, cyclohexane, 2-methylhexane, 3-methylhexane, 2,5-dimethylhexane, heptane, 2-methylheptane, 3-methylheptane, 3-ethylheptane, 2,2,4,6,6-pentamethylheptane, 3-ethyl-3-methylheptane, 3-methylheptene, octane, 2-methyloctane, 4-ethyloctane, nonane, 3-methylnonane, decane, and dodecane.

[0019] Specific examples of alcohol compounds include 2-methyl-2-propanol, 2-methylpropanol, ethanol, and 1-propanol.

[0020] Specific examples of aldehyde compounds include formaldehyde, acetaldehyde, 2-methylpropanal, and 3-methylbutanal.

[0021] Specific examples of ketone compounds include acetone, MEK, MIBK, and 3,3-dimethyl-2-butanone.

[0022] Specific examples of carboxylic acid compounds include acetic acid, isovaleric acid, 2-methylpropanoic acid, and 2,2-dimethylpropanoic acid.

[0023] Specific examples of ester compounds include ethyl acetate, butyl acetate, and the like.

[0024] Carbon dioxide originates from atmospheric components, aldehydes, ketones, carboxylic acids and alcohols originate from the thermal history of the low gas-releasing sealant film or heat insulating retaining laminate and atmospheric components, and esters originate from the adhesive layer.

[0025] <Gas barrier substrate layer> The gas barrier substrate layer in the present invention refers to a substrate layer having gas barrier properties, and is composed of one layer such as a gas barrier resin film having gas barrier properties and substrate properties. Alternatively, the gas barrier layer may have a multi-layer structure including a gas barrier layer and a substrate layer. Furthermore, in order to improve adhesion, an adhesive layer may be provided between each layer constituting the gas barrier substrate layer or between each layer and other layers, and a desired surface treatment layer may be provided in advance on the surface of each layer as necessary.

[0026] For example, a corona-treated layer, an ozone-treated layer, a plasma-treated layer, an oxidation-treated layer, or the like can be formed by optionally carrying out pretreatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, or the like, glow discharge treatment, or oxidation treatment using chemicals, or the like.

[0027] Alternatively, various coating layers such as a primer coating layer, an undercoating layer, an anchor coating layer, an adhesive layer, and a vapor-deposited anchor coating layer may be formed on the surface of each layer to form a surface treatment layer. For the various coating layers, for example, a resin composition containing a polyester resin, a polyamide resin, a polyurethane resin, an epoxy resin, a phenol resin, a (meth)acrylic resin, a polyvinyl acetate resin, a polyolefin resin such as polyethylene or polypropylene, or a copolymer or modified resin thereof, a cellulose resin, or the like as the main component of the vehicle can be used. The thickness of the gas barrier substrate layer is preferably 5 μm or more and 100 μm or less, more preferably 7 μm or more and 75 μm or less. If the thickness is less than the above range, the rigidity and / or gas barrier properties may be insufficient, and if the thickness exceeds the above range, the rigidity may be too high, resulting in reduced workability.

[0028] [Base material layer] The substrate layer may be a resin film, a paper material, or the like, and may be composed of a single layer or a multilayer structure including two or more layers having the same or different compositions.

[0029] The thickness of the base layer varies depending on the material, but in the case of a resin film, it is preferably 15 μm or more and 60 μm or less, more preferably 7 μm or more and 45 μm or less. The resin film used for the base layer may be a film of a thermoplastic resin, and it is preferable that the thermoplastic resin has excellent chemical and physical strength, can withstand the conditions for forming a vapor-deposited film of a metal or metal oxide, and can well retain the properties of the vapor-deposited film without impairing the properties.

[0030] Examples of such resins include polyolefin resins such as polyethylene resins and polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), poly(meth)acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as various nylons, polyurethane resins, acetal resins, and cellulose resins. In the present invention, the resin is preferably a polyester resin, a polyamide resin, or a polyolefin resin, and in particular, polyethylene terephthalate (PET), nylon, or polypropylene (PP).

[0031] In the present invention, the thermoplastic resin used in the substrate layer can be formed into a film by various film-forming methods. For example, a method of forming a film using one type of resin by a film forming method such as an extrusion method, a cast molding method, a T-die method, a cutting method, or an inflation method, a method of forming a multi-layer film by co-extrusion using two or more types of resins, a method of mixing two or more types of resins before film formation, and forming a film by the above-mentioned film formation method. Furthermore, a film can be uniaxially or biaxially stretched using a tenter method, a tubular method, or the like.

[0032] Alternatively, one or more resins may be coated on another resin film by applying and drying, or a molten resin may be laminated by a T-die method or the like. In the present invention, the resin film is preferably a biaxially oriented PET film, a biaxially oriented nylon film, or a biaxially oriented PP film or sheet.

[0033] In addition, when forming the resin film, various plastic compounding agents and additives can be added to the resin film for the purpose of improving or modifying, for example, the processability, heat resistance, weather resistance, mechanical properties, dimensional stability, oxidation resistance, slipperiness, release properties, flame retardancy, mold resistance, electrical properties, strength, etc. of the film. The amount of these additives can range from a very small amount to several tens of percent and can be added at any amount depending on the purpose. In the above, examples of common additives that can be used include lubricants, crosslinking agents, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, modifying resins, and the like.

[0034] [Gas barrier layer] The gas barrier layer is a layer that, in a vacuum insulation panel produced using the heat insulating laminate of the present invention, prevents atmospheric gas from passing through the heat insulating laminate from the outside to the inside of the vacuum insulation panel. The gas barrier layer can be made of one or a combination of two or more selected from the group consisting of a gas barrier resin film, a metal foil, a resin film with a metal or metal oxide vapor-deposited layer, and a gas barrier resin coating film.

[0035] As the gas barrier resin film, for example, a resin film made of a resin such as PET, polybutylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polyvinyl alcohol, or an ethylene-vinyl alcohol copolymer is preferable.

[0036] The metal foil is preferably an aluminum foil having a thickness of 3 μm or more and 15 μm or less.

[0037] The resin film with a metal or metal oxide vapor deposition layer is preferably one in which an aluminum vapor deposition film, a silica vapor deposition film, or an aluminum oxide vapor deposition film is formed on at least one surface of the above-mentioned base resin film. Commercially available resin films with an aluminum oxide vapor deposition film include, for example, alumina vapor deposition IB-PET-PIR (thickness 12 μm) and silica vapor deposition IB-ON-UB (thickness 15 μm) manufactured by Dai Nippon Printing Co., Ltd., which are PET films with alumina vapor-deposited on one side by the PVD method.

[0038] As the gas barrier resin coating film, a coating film containing a sol-gel hydrolysis polycondensate formed from a metal alkoxide and a water-soluble polymer is preferred.

[0039] The metal foil for the gas barrier layer, or the resin film with the metal or metal oxide vapor-deposited layer can be bonded to other layers using a dry lamination adhesive. Alternatively, by using a resin film for the base layer as the resin film of the resin film with a metal or metal oxide vapor-deposited layer, lamination onto the base layer can be omitted.

[0040] <Low gas release sealant layer> The low gas-releasing sealant layer is a layer containing a low gas-releasing resin having heat-sealing properties, and has heat-sealing properties and low gas-releasing properties. The low gas release sealant layer may be a single layer structure or a multi-layer structure of two or more layers. It is also possible. For example, it may be composed of a low gas release layer that contains a large amount of low gas release resin and has excellent low gas release properties, and a heat seal layer that contains a large amount of heat sealable resin and has excellent heat sealing properties, or it may have a three-layer structure in which a low gas release layer is sandwiched between two heat seal layers.

[0041] The content of the low gas-releasing resin in the entire low gas-releasing sealant layer is preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 99.9% by mass or less. If it is less than the above range, the low gas-releasing property of the low gas-releasing sealant may be insufficient. When the low outgassing sealant layer has a multi-layer structure having a low outgassing layer and a heat seal layer, etc., in order to improve the heat sealability, it is preferable that the outermost layer on at least one side of the low outgassing sealant layer is a heat seal layer. However, it is more preferable that the low outgassing sealant layer has a single layer structure that is excellent in both low outgassing and heat sealability by using a low outgassing resin with excellent heat sealability. Furthermore, the low outgassing resin contained in the low outgassing layer and the low outgassing resin contained in the heat seal layer may be the same or different.

[0042] Inside the vacuum insulation panel, the low outgassing sealant layer is in contact with the space inside the vacuum insulation panel and is present at the joint interface of the heat seal part, so that the low outgassing properties can be adjusted by adjusting the thickness of the low outgassing sealant layer. In order to obtain a balance between good heat sealability and low gas release, the thickness of the low gas release sealant layer is preferably 25 μm or more and 150 μm or less, and more preferably 30 μm or more and 100 μm or less. If the thickness is thinner than the above range, the heat sealability may be insufficient, and if the thickness is thicker than the above range, the low gas release property may be inferior.

[0043] And, the low outgassing sealant layer may further contain minor amounts of slip agents, antiblocking agents, antioxidants, solvents, and other additives. The low gas release sealant layer of the present invention preferably contains an antioxidant in order to suppress the generation of gas released due to resin deterioration in a high temperature environment. Conversely, it is preferable to limit the use of additives that may increase the amount of gas released at high temperatures.

[0044] [Low gas emission layer] The low gas release layer is a layer containing a large amount of a low gas release resin, and may further contain other resins and various additives such as antioxidants, to the extent that the low gas release properties are not significantly impaired. The low outgassing sealant layer may contain one low outgassing layer or two or more layers having the same or different compositions.

[0045] The thickness of the low gas release layer is preferably 5 μm or more and 80 μm or less, more preferably 7 μm or more and 75 μm or less. If the thickness is thinner than the above range, the effect of providing the low gas release layer may be insufficient, and if the thickness is thicker than the above range, the low gas release property may not be improved much, and the rigidity of the low gas release sealant layer may become too strong, resulting in a decrease in workability.

[0046] [Heat seal layer] The heat seal layer is a layer containing a heat sealable resin and has high heat sealability. Here, the heat sealable resin is preferably a low outgassing resin having heat sealability in order to achieve both high heat sealability and low outgassing property. However, other resins and various additives such as antioxidants may be contained within the range that does not significantly impair the heat sealability and low gas release properties. The low gas releasing sealant layer may contain one heat seal layer or two or more layers having the same or different compositions.

[0047] In order to exhibit good heat sealability, the thickness of the heat seal layer is preferably 3 μm or more and 30 μm or less, more preferably 5 μm or more and 25 μm or less. If the thickness is thinner than the above range, the heat sealability may be insufficient, and if the thickness is thicker than the above range, the heat sealability may not be improved much and the rigidity of the low gas release sealant layer may become too weak, resulting in a decrease in workability.

[0048] [Low gas emission resin] A low gas release resin is a resin that releases a small amount of gas, and the amount of gas released varies depending on the shape and thermal history of the resin. By incorporating a low-gas-releasing resin with heat-sealing properties into the low-gas-releasing sealant layer that contacts the internal space of the vacuum insulation panel, the low-gas-releasing sealant layer is imparted with heat-sealing properties, the amount of gas released is reduced, and an increase in air pressure inside the vacuum insulation panel can be suppressed. The amount of gas released from low gas release resins is highly correlated with the concentration of elutable total organic carbon (TOC) contained in the low gas release resins. TOC is the concentration of the total amount of organic matter (organic carbon) in water that can be oxidized, expressed as a carbon concentration. It is used as one of the most representative water quality indicators and is standardized in JIS K0805 (total organic carbon (TOC) automatic measuring device) etc.

[0049] The concentration of soluble total organic carbon (TOC) contained in the film made of the low gas release resin in the present invention is preferably 1.5 ppm or more and 250 ppm or less, and more preferably 5 ppm or more and 200 ppm or less. It is difficult to prepare a film having a concentration lower than the above range, and it is difficult to show a significant difference in practical effect. If it is higher than the above range, the low gas release resin may become insufficient.

[0050] The reason why the concentration of elutable TOC for the low outgassing resin as a single raw material is measured in a film state rather than in the state of raw material pellets, etc., is that when the low outgassing resin is made into a film to form a low outgassing sealant layer, etc., it is subjected to various heat histories, etc., which may increase the amount of eluted TOC.

[0051] The concentration of soluble total organic carbon (TOC) contained in the film made of the above-mentioned low outgassing resin is determined, for example, by filling a pouch made of a film made of the low outgassing resin of the present invention with distilled water as the filling water, allowing the organic carbon to elute, measuring the TOC concentration of the filling water, subtracting the TOC concentration of the filling water before filling as a blank to calculate the increase in TOC concentration, and then calculating the soluble TOC concentration contained in the film made of the low outgassing resin.

[0052] The increase in TOC concentration of the filling water is preferably 0.01 ppm or more and 1.5 ppm or less, more preferably 0.02 ppm or more and 1.45 ppm or less, and even more preferably 0.025 ppm or more and 1.4 ppm or less. It is difficult to prepare something less than the above range, and it is difficult to show a significant difference in practical effect. If it is more than the above range, the low gas release resin may have insufficient low gas release properties. From the viewpoint of both cost and performance, it is preferable that it is in the above range.

[0053] More specifically, although it depends on the application, it is preferable that the temperature of the water during filling is 40°C to 80°C, the temperature during storage is 25°C to 50°C, the storage period is several days to 4 weeks, and the TOC concentration of the water is measured using a total organic carbon meter or HS-GC.

[0054] In the present invention, the elutable TOC concentration contained in the resin film made of the low gas release resin was measured using a 15 cm x 44 cm inner dimension measuring instrument made of the low gas release resin. It is preferable to fill a 2.0 cm pouch with 1,000 g of distilled water (distilled water for high performance liquid chromatography, manufactured by Junsei Chemical Co., Ltd.) at 65°C as the filling water, seal it, store it at 35°C for 2 weeks, and then measure the TOC concentration of the filled water using a TOC-L total organic carbon meter (manufactured by Shimadzu Corporation) as the standard method, and calculate the leachable TOC concentration contained in the resin film made of a low gas release resin.

[0055] For example, when a pouch measuring 15 cm x 44 cm x 50 μm in thickness is used and 1,000 g of water is filled, the concentration C of leachable TOC contained in the film made of low gas releasing resin is calculated from the increase in TOC concentration in the filled water as shown below. Filled water (distilled water) weight: W1 = 1000 [g] Density of film made of low gas emission resin: S [g / cm 3 ] Pouch size: 15cm x 44cm x 50μm thick Pouch weight: W2=15×44×50×10-4 ×2×S=6.6×S[g] Concentration of soluble TOC contained in a film made of low gas emission resin: C [ppm] Increase in TOC concentration in filling water: X [ppm] Then, Total weight of extractable TOC contained in the film made of low gas emission resin = C × W2 [g] This dissolves in W1[g] of water, so X=C×W2 / W1=C×6.6×S×10 -3 [ppm] The TOC concentration C of the elutable TOC contained in the film made of low gas release resin is calculated from the following formula: C = X / (6.6 × S × 10 -3 ) [ppm] For example, the density S of the film made of low gas releasing resin that constitutes the pouch is 0.92 [g / cm 3 ], if the increase in TOC concentration of the filling water is 0.01 [ppm], C = 0.01 / (6.6×0.92×10 -3 )=1.64[ppm] It is calculated as follows:

[0056] The density of low gas emission polyethylene resin is 0.915g / cm 3 More than 0.935g / cm 3 Less than 0.919 g / cm is preferred. 3 More than 0.933g / cm 3 The following is more preferable: A polyethylene resin having a density within the above range tends to be able to reduce the amount of organic gas released.

[0057] The MFR (melt flow rate) of the low gas release polyethylene resin is preferably 0.2 g / 10 min or more and 10 g / 10 min or less, and more preferably 0.5 g / 10 min or more and 7 g / 10 min or less. If the MFR is within the above range, even when mixed with other resins or various additives, the resin can maintain a good MFR and exhibit good film-forming properties and adhesive properties.

[0058] As the low gas-releasing resin, a polyethylene resin (low gas-releasing polyethylene resin) is preferable because it has excellent heat sealability, resistance to UV or EB irradiation and heating, and resistance to decomposition. Low gas release polyethylene resins originally contain a small amount of gas that can be released, and are resistant to UV or EB irradiation and heating and therefore difficult to decompose, thereby enabling the amount of gas released to be reduced.

[0059] Specific examples of polyethylene species in low gas emission polyethylene resins include low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-methyl methacrylic acid copolymer, and ethylene-propylene copolymer. Examples of resins that can be used include, but are not limited to, low outgassing resins such as coalesced resins and mixtures of these resins.

[0060] Among the above, one or a combination of two or more selected from the group consisting of MDPE, LDPE and LLDPE is preferred. The LLDPE is preferably one or a combination of two or more selected from the group consisting of C4-LLDPE, C6-LLDPE, and C8-LLDPE, and C6-LLDPE is more preferable.

[0061] Here, C4-LLDPE is a linear low-density polyethylene made of a copolymer of ethylene and 1-butene, C6-LLDPE is a linear low-density polyethylene made of a copolymer of ethylene and 1-hexene and / or 4-methyl-1-pentene, and C8-LLDPE is a linear low-density polyethylene made of a copolymer of ethylene and 1-octene. Each of the molecular structures has an ethylene-derived LLDPE main chain with side chains having 4, 6 and 8 carbon atoms derived from 1-butene, 1-hexene and / or 4-methyl-1-pentene and 1-octene, respectively.

[0062] In order to keep the amount of released gas contained in the resin low, for example, it is effective to reduce the amount of unreacted raw materials, low molecular weight products, and by-products, and to remove the polymerization catalyst when producing the resin.Specific examples of such methods include improving the purity of raw materials, precisely controlling conditions such as reaction temperature and pressure, removing unreacted raw materials, low molecular weight products, by-products, and polymerization catalysts by distillation or washing, and preventing oxidation due to exposure to oxygen in the air at high temperatures. Another method is to limit the use of additives that may increase the amount of outgassing when the resin is pelletized or filmed, and to prevent oxidation due to high temperatures. Specific additives include lubricants, antioxidants, antiblocking agents, solvents, etc.

[0063] [Antioxidants] The thermal insulation support laminate preferably further contains an antioxidant in the low outgassing sealant layer. The content of the antioxidant in the entire low gas release sealant layer is preferably 0.005 mass% or more and 0.5 mass% or less, and more preferably 0.04 mass% or more and 0.4 mass% or less. If the content is less than the above range, the effect of containing the antioxidant may be insufficient, and if the content is more than the above range, the effect of increasing the antioxidant will not change much, and the heat sealability may tend to deteriorate. The antioxidant may be contained in the low gas releasing layer and / or the heat seal layer that constitutes the low gas releasing sealant layer, and the antioxidant contained in the low gas releasing layer and the antioxidant contained in the heat seal layer may be the same or different.

[0064] Specific examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, and mixed phenol-based and phosphorus-based antioxidants. It is preferable to use one or a combination of two or more selected from the group consisting of these antioxidants.

[0065] <Adhesive layer> The heat insulating laminate of the present invention can be laminated by providing an adhesive layer between each of the constituent layers and between layers within each layer. Furthermore, before forming the adhesive layer, an anchor coat layer may be formed in advance on the surface of the layer to be adhered in order to improve adhesion.

[0066] The adhesive (adhesive composition) forming the adhesive layer may be of a thermosetting type, an ultraviolet-curing type, an electron beam-curing type, or the like, and may be in any form, such as an aqueous type, a solution type, an emulsion type, a dispersion type, or the like. In addition, the adhesive may be in any form, such as a film / sheet type, a powder type, a solid type, or the like, and the adhesive mechanism may be in any form, such as a chemical reaction type, a solvent volatilization type, a thermal melting type, a thermal pressure type, or the like.

[0067] Examples of such adhesives include polyvinyl acetate adhesives such as polyvinyl acetate and vinyl acetate-ethylene copolymers, polyacrylic acid adhesives made of copolymers of polyacrylic acid and polystyrene, polyester, polyvinyl acetate, etc., cyanoacrylate adhesives, ethylene copolymer adhesives made of copolymers of ethylene and monomers such as vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc., cellulose adhesives, polyurethane adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, polyolefin adhesives, amino resin adhesives made of urea resin or melamine resin, etc., phenol resin adhesives, epoxy adhesives, reactive (meth)acrylic adhesives, elastomer adhesives made of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc., silicone adhesives, inorganic adhesives made of alkali metal silicates, low-melting point glass, etc. When a laminate is formed by coextrusion and film formation using an inflation method, among the above, polyolefin-based adhesives are preferred.

[0068] In one embodiment of the present invention, the adhesive layer may be a layer made of any of an adhesive for EC (extrusion coating), an adhesive for dry lamination, an adhesive for non-solvent lamination, and the like. When an EC adhesive is used, although there are no particular limitations, for example, the adhesive is first heated and melted, expanded and stretched in the required width direction using a T-die or the like, extruded into a curtain shape, allowed to flow down onto the layer to be bonded, and then sandwiched between a rubber roll and a cooled metal roll, thereby simultaneously forming an adhesive layer and bonding and laminating to the layer to be bonded.

[0069] In another embodiment, the adhesive layer may be formed by sand lamination. In this case, any resin that can be applied by heating and melting in an extruder can be used for the adhesive layer. Specifically, the resins listed above as thermoplastic resins having heat sealability can be preferably used.

[0070] When using a dry lamination adhesive, the adhesive dispersed or dissolved in a solvent is applied onto one film and dried, and the other film is then laminated on top of it. The adhesive is then cured by aging at 30 to 120°C for several hours to several days to bond and laminate the films.

[0071] When using a non-solvent laminating adhesive, the adhesive itself is applied to the layer to be adhered without being dispersed or dissolved in a solvent, and then dried. The film that will form the other layer is then laminated on top of it, and the adhesive is hardened by aging at 30 to 120°C for several hours to several days before laminating.

[0072] The adhesive for dry lamination or the adhesive for non-solvent lamination can be used by coating, for example, by roll coating, gravure roll coating, kiss coating, etc., and the coating amount is 0.1 to 10 g / m 2 By setting the coating amount within the above range, good adhesion can be obtained.

[0073] (Anchor coat layer) The anchor coat layer can be formed from any anchor coat agent. Examples of anchor coating agents that can be used include organic titanium-based, isocyanate (urethane-based), polyethyleneimine-based, acid-modified polyethylene-based, polybutadiene-based, polyacrylic-based, polyester-based, epoxy-based, polyvinyl acetate-based, cellulose-based, and other anchor coating agents.

[0074] [Method of manufacturing the heat insulating laminate] The preparation method described below is an example and is not intended to limit the present invention. The formation and lamination of each layer constituting the heat insulating laminate can be carried out by any method, such as wet lamination, dry lamination, solventless dry lamination, extrusion lamination, T-die coextrusion molding, coextrusion lamination, inflation molding, and the like. The obtained heat insulating laminate can be subjected to secondary processing for the purpose of imparting surface functions such as chemical functions, electrical functions, magnetic functions, mechanical functions, friction / wear / lubrication functions, optical functions, thermal functions, and biocompatibility.

[0075] Examples of secondary processing include embossing, painting, adhesives, printing, metallizing (plating, etc.), machining, surface treatment (antistatic treatment, corona discharge treatment, plasma treatment, photochromic treatment, physical vapor deposition, chemical vapor deposition, coating, etc.), and the like.

[0076] As an example, the following describes the production of a heat insulating laminate (heat insulating packaging material) having a layer structure of gas barrier substrate layer [substrate layer / adhesive layer / substrate layer / adhesive layer / gas barrier layer] / adhesive layer / low gas release sealant layer.

[0077] (Preparation of low gas emission sealant film) A sealant layer resin composition for a low gas releasing sealant layer is prepared, and a low gas releasing sealant film is obtained by an inflation method.

[0078] (Preparation of heat insulating laminate) Next, the low gas-releasing sealant film obtained above for the low gas-releasing sealant layer, the base film 1 and base film 2 for the base layer, and an aluminum foil for the gas barrier layer were dry laminated in this order via a DL adhesive for the adhesive layer (coating amount: 3.5 g / m 2 , drying temperature: 70° C.) to obtain a heat insulating laminate having the above layer structure.

[0079] (Another embodiment of a method for forming and laminating a low gas-releasing sealant layer) The low gas release sealant layer may be laminated on another layer such as a gas barrier substrate layer by extrusion coating or co-extrusion. Even in the case of extrusion coating, the layer may be laminated via an adhesive layer as necessary.

[0080] <Thermal insulation packaging materials> The heat insulating packaging material of the present invention is a packaging material made from the heat insulating laminate of the present invention, and may be the same as the heat insulating laminate, and may further include various functional layers, printed layers, etc., as necessary. The heat insulating packaging material of the present invention can also be subjected to lamination (dry lamination or extrusion lamination), bag making, and other post-treatments. A specific example of the heat insulating property-retaining packaging material of the present invention is a heat insulating property-retaining packaging material for a vacuum insulation panel.

[0081] <Thermal insulation packaging> The heat insulating packaging of the present invention is a packaging produced using the heat insulating packaging material of the present invention. A specific example is a vacuum insulation panel. The vacuum insulation panel can be used to produce a highly insulating container, such as a refrigerator, a freezer, a low-temperature container, a cooler box, a heat-retaining cabinet, a greenhouse, or a heat-retaining box. EXAMPLES

[0082] Details of the raw materials used in the examples are as follows. [Low gas emission resin] Low gas emission resin 1: Urutozex 3520L, manufactured by Prime Polymer Co., Ltd. C6-LLDPE, density 0.931g / cm 3 , MFR 2.1g / 10min. TOC concentration in the extracted water was 0.26ppm, and the elutable TOC concentration in the resin film was 42.3ppm. Low gas emission resin 2: Prime Polymer Co., Ltd., Neozex 3510F. C4-LLDPE, density 0.933g / cm 3 , MFR 1.6g / 10min. TOC concentration in the extracted water was 0.32ppm, and the elutable TOC concentration in the resin film was 52.0ppm. Low gas emission resin 3: Urutozex 2021L, manufactured by Prime Polymer Co., Ltd. C6-LLDPE, density 0.919g / cm 3 , MFR 2.0g / 10min. TOC concentration in the extracted water was 0.56ppm, and the elutable TOC concentration in the resin film was 92.3ppm. Low gas emission resin 4: Novatec LC522, manufactured by Japan Polyethylene Co., Ltd. LDPE. Density 0.923g / cm 3 , MFR4g / 10min. TOC concentration in the extracted water was 0.32ppm, and the elutable TOC concentration in the resin film was 52.5ppm.

[0083] [General-purpose polyethylene] General-purpose polyethylene 1: Evolu SP4020 manufactured by Prime Polymer Co., Ltd. C6-LLDPE, density 0.937g / cm 3 , MFR 1.7g / 10min. TOC concentration in the extracted water was 2.85ppm, and the elutable TOC concentration in the resin film was 461ppm. General-purpose polyethylene 2: Prime Polymer Co., Ltd., Evolu SP1520. C6-LLDPE, density 0.913g / cm 3 , MFR 2.0g / 10min. TOC concentration in the extracted water was 3.05ppm, and the elutable TOC concentration in the resin film was 506ppm.

[0084] [Antioxidants] Antioxidant 1: EAG-5, manufactured by Prime Polymer Co., Ltd. Contains a total of 5% by mass of phenol-based antioxidant and phosphorus-based antioxidant. MFR 4.5g / 10min.

[0085] [Film for base layer] Base film 1: Manufactured by Unitika Ltd., emblem ON, thickness 25μm. Base film 2: Toyobo Co., Ltd., Espet T4102, thickness 12 μm. Base film 3: IB-PET-PIR manufactured by Dai Nippon Printing Co., Ltd. Alumina-deposited PET film with a barrier-coat resin layer. Thickness: 12 μm.

[0086] [Metal foil for gas barrier layer] Aluminum foil 1: Manufactured by Toyo Aluminum Co., Ltd. Thickness: 6 μm.

[0087] [glue] DL Adhesive 1: ADOLOCK RU77T / H7 manufactured by Rock Paint Co., Ltd. Polyester adhesive.

[0088] <Preparation of low gas release sealant layer resin composition> By dry blending the raw materials according to the composition shown in Table 1, low gas release sealant layer resin compositions 1 and 2 were obtained.

[0089] [Table 1]

[0090] <Example 1> [Preparation of low gas emission sealant film] Using the low gas releasing resin 1, a low gas releasing sealant film 1 was obtained by an inflation method. The obtained low gas release sealant film 1 was used to evaluate film formability and low gas release properties.

[0091] [Preparation of heat insulating laminate] Next, the low gas release sealant film 1 and the base film 1, and the base film 2 and the aluminum foil 1 obtained above were dry laminated with DL adhesive 1 (coating amount: 3.5 g / m 2 , drying temperature: 70° C.) to obtain a heat insulation retaining laminate 1 having the following layer structure. Composition of heat insulating laminate 1: Gas barrier base layer (base film 1 / DL adhesive 1 / base film 2 / DL adhesive 1 / aluminum foil 1) / DL adhesive 1 / low gas release sealant film 1 The obtained heat insulation retaining laminate 1 was used to carry out evaluation of heat sealability and heat insulation. The evaluation results are shown in Table 2.

[0092] <Examples 2 to 7, Comparative Examples 1 to 2> Using the raw materials shown in Table 2, and following the same procedures as in Example 1, low gas releasing sealant films and heat insulating retaining laminates were produced and similarly evaluated.

[0093] <Evaluation method> [Film forming property] The appearance of the low gas emission sealant film was observed and evaluated sensorily according to the following criteria: ○: Film formation is possible without wrinkles or bumps. ×: Numerous wrinkles and bumps were generated, making film formation difficult.

[0094] [Gas release amount] The low outgassing sealant film was cut to 50 mm x 10 mm, and two pieces of film were placed in a test tube and heated at 90°C for 60 minutes. The air in the test tube was collected and the concentration of the carbon-16 organic gas component in the collected air was measured by gas chromatography, and the amount of the carbon-16 organic gas component released per unit volume by the low outgassing sealant film was calculated.

[0095] [Heat sealability] The heat insulating laminate was cut into 10cm x 10cm pieces, the low gas releasing sealant layer faces were overlapped, and a 1cm x 10cm area was heat sealed under the following conditions using a heat seal tester (Tester Sangyo Co., Ltd.: TP-701-A). The edges were not heat sealed and were bonded. A test piece for the peel strength was prepared in a bifurcated state, without any adhesive. This test piece was cut into a strip of 15 mm width, and each bifurcated end was attached to a tensile tester to measure the peel strength (N / 15 mm) under the conditions below, and the pass / fail judgment was made according to the pass / fail judgment criteria below. Heat sealing conditions Temperature: 160℃ Pressure: 1kgf / cm 2 Time: 1 second Test conditions Test speed: 300mm / min Load range: 50N Pass / Fail Criteria ○: 30N / 15mm or more, passed. ×: Less than 30N / 15mm, failing.

[0096] [Thermal insulation maintenance] Two pieces of insulating laminate cut into a rectangle measuring 40 cm wide and 50 cm long were prepared, and the low gas-releasing sealant layers of the two insulating laminates were stacked facing each other, and a bag with one side open was obtained by heat-sealing an area of ​​2 cm to 3 cm from the ends of the outer edges of the three sides. From the opening of the bag, a 29cm wide x 30cm long x 3cm thick glass wool (weight 800g / m) is inserted as a core material. 2 After placing a binder-free glass wool (product name: White Roll WR800, manufactured by Mag Isover) in the bag, air was sucked out from the opening of the bag. Suction was performed using a vacuum packaging machine (MVR-1000 model, manufactured by Shitara Seisakusho), and when the pressure inside the bag was reduced to 0.05 Pa, an area of ​​5 to 6 cm from the edge of the outer edge of the remaining side was heat sealed. The heat sealing was performed using a heat sealer (Impulse Sealer FA-600-10W, manufactured by Fuji Impulse Co., Ltd.). Furthermore, the entire outer edge was folded and fixed with tape to prepare a simple vacuum insulation panel as a test piece for evaluating insulation maintenance, in which the core material was wrapped in the insulation retaining laminate. The thermal conductivity was measured in the thickness direction of the simple vacuum insulation panel. First, the thermal conductivity was measured immediately after preparation (LMD1), and then the thermal conductivity was measured after storage for 1000 hours in a 100°C environment (LMD2). Then, Δthermal conductivity was calculated using the following formula, and the pass / fail of the insulation maintenance was judged according to the pass / fail judgment criteria below. ΔThermal conductivity = LMD2-LMD1 Pass / Fail Criteria Pass: ΔThermal conductivity is 7.0mW / mK or less. Fail: Δthermal conductivity is greater than 7.0 mW / mK.

[0097] [Leachable TOC concentration] Water was filled into a pouch made of a resin film, which was then sealed and stored at 35° C. for 2 weeks. The TOC concentration of the water was then measured to determine the increase in TOC concentration. Pouch size: Inner dimensions 15cm x 44cm x 50μm thickness Filling water: Distilled water for high performance liquid chromatography manufactured by Junsei Chemical Co., Ltd. 65°C 1000g. TOC concentration measuring device: TOC-L total organic carbon meter manufactured by Shimadzu Corporation. Next, the concentration of soluble TOC contained in the resin film was calculated from the increased concentration of TOC in the filling water obtained above using the following formula. C=X×W1 / W2 =X×W1 / (6.6×S) C: Concentration of elutable TOC contained in the resin film [ppm] X: Increased concentration of TOC in the filling water [ppm] W1: Filled water weight = 1000[g] W2: Pouch weight = 15 x 44 x 50 x 10 -4 ×2×S=6.6×S[g] S: Density of resin film [g / cm 3 ]

[0098] [Table 2]

[0099] <Summary of results> The low gas releasing sealant films of all the Examples exhibited good film-forming properties and low gas releasing properties, and the heat insulating property-retaining laminates exhibited good heat sealing properties and heat insulating property-retaining effects. However, the sealant films of Comparative Examples 1 and 2, which did not contain a low gas-releasing resin, released a large amount of gas, and the laminates having the gas barrier substrate layer laminated thereon showed poor heat insulation maintaining effect. [Explanation of symbols]

[0100] 1. Thermal insulation retaining laminate 2. Thermal insulation packaging materials 3 Gas barrier substrate layer 4. Low-gassing sealant layer 4a Low gas release layer 4b Heat seal layer 5 Adhesive layer 10. Reduced pressure packaging 11 Core material 12 Heat seal joint

Claims

1. A thermal insulation retaining laminate for a vacuum insulation panel, comprising: The heat insulating support laminate has a gas barrier substrate layer and a low gas release sealant layer, The low gas releasing sealant layer contains a low gas releasing resin having heat sealability, The low gas emission resin is a polyethylene resin having a density of 0.915 g / cm ３ Above, 0.935g / cm ３ is as follows: The concentration of elutable total organic carbon (TOC) contained in the film made of the low gas emission resin is 1.5 ppm or more and 250 ppm or less, the low outgassing sealant layer is a layer made of a low outgassing sealant film, The low gas release sealant film has a carbon number of 16 organic gas component released when heated in air at 90° C. for 60 minutes, and the amount of the low gas release sealant film per unit volume of the low gas release sealant film is 10 μg / cm ３ Above, 1000μg / cm ３ is less than or equal to A heat insulating laminate comprising:

2. 2. The heat insulating laminate according to claim 1, wherein the content of the low gas releasing resin in the entire low gas releasing sealant layer is 70% by mass or more and 99.9% by mass or less.

3. The heat insulating laminate according to claim 1 or 2, characterized in that the low gas releasing resin is one or a combination of two or more selected from the group consisting of medium density polyethylene, low density polyethylene and linear low density polyethylene.

4. The heat insulating laminate according to any one of claims 1 to 3, wherein the low gas releasing sealant layer further contains an antioxidant.

5. 5. The heat insulating laminate according to claim 4, wherein the content of the antioxidant in the entire low gas releasing sealant layer is 0.005% by mass or more and 0.5% by mass or less.

6. A heat insulating packaging material for a vacuum insulation panel, produced using the heat insulating laminate according to any one of claims 1 to 5.

7. A vacuum insulation panel produced using the heat insulating packaging material according to claim 6.

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