JP3797886B2 - Insulated container and manufacturing method thereof - Google Patents

Description

【００６７】
表１に示すように、内層と断熱層との間に混合層が形成された容器（実施例１，２）は、薄肉、軽量で、所望の機械的強度及び断熱性を有し、変形による層間剥離も起こらないことが確認された。これに対し、断熱材を有しない容器（比較例１）、断熱材からなる断熱層を有しているが混合層が形成されていない容器（比較例２）では、薄肉、軽量にすると、横置きにしたときの変形荷重（把持強度に相当）が充分に得られず（比較例１）、また、混合層が形成されていない場合には、層間剥離が生じて容器内面にしわや亀裂が発生することが確認された。
【００６８】
【発明の効果】
本発明によれば、薄肉、軽量で、且つ座屈強度及び断熱性を併せ持つ断熱容器が提供される。
【図面の簡単な説明】
【図１】本発明の断熱容器の一実施形態を示した概略半断面図である。
【図２】本発明の断熱容器の製造工程の一部を示す概略図であり、（ａ）は、外層の抄紙工程を示す図、（ｂ）は外層の脱水・乾燥工程を示す図、（ｃ）は内層の抄紙工程を示す図、（ｄ）は内層の外表面を発泡剤で被覆している工程を示す図、（ｅ）は内層と外層の重ね合わせ工程を示す図、（ｆ）は乾燥工程を示す図である。
【図３】本発明の断熱容器の製造方法における樹脂層の形成工程を示す概略図であり（ａ）は、真空成形機に容器をセットした状態を示す概略断面図であり、（ｂ）は（ａ）のフランジ部における樹脂フィルムの密着状態を示す拡大断面図である。
【符号の説明】
１ 断熱容器
２ 内層
３ 外層
４ 断熱層
５ 樹脂層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat insulating container that is thin, lightweight, and excellent in buckling strength and heat insulation.
[0002]
[Prior art and problems to be solved by the invention]
As a conventional technique related to a heat insulating container made of pulp mold that includes an inner layer and an outer layer and a heat insulating layer between the inner layer and the outer layer, for example, a heat insulating container described in JP-A-11-301753 is disclosed. Are known.
This heat insulating container made of pulp mold is formed by forming a heat insulating space by providing a gap between an inner layer and an outer layer made of pulp mold.
By the way, in this conventional heat insulating container, since the heat insulating space is a gap, in order to obtain a desired mechanical strength, the mechanical strength is increased by increasing the basis weight and density of the inner layer and the outer layer. It had to be thick, and the weight of the entire container had to be heavy.
[0003]
On the other hand, JP 2000-109123 A discloses a container in which an inner layer and an outer member made of a paper base material are used, and an intermediate layer made of a foaming material containing pulp is bonded with an adhesive therebetween. Yes.
However, since the foaming agent containing this pulp does not obtain a high expansion coefficient even if foamed, it is necessary to use a large amount of the foaming agent in order to obtain a desired heat insulating property. I had to. In addition, if the container is made thinner and the container is made lighter, the adhesive penetrates into the base material, which causes the disadvantage that the base material is discolored or softly deformed. There was a problem that the adhesive for obtaining sufficient adhesion with the layer could not be applied, and the base material and the intermediate layer were easily peeled off.
[0004]
  Therefore, the object of the present invention is thin, lightweight, and has both buckling strength and heat insulation.3D paperInsulated containerAnd its manufacturing methodIs to provide.
[0005]
[Means for Solving the Problems]
The inventors have a heat insulating layer formed of a heat insulating material between an inner layer and an outer layer made mainly of pulp, and the inner layer and the heat insulating layer are mixed layers in which the pulp and the heat insulating material are mixed. It has been found that a heat insulating container having both desired buckling strength and heat insulating properties can be obtained by being fixed through a thin wall and light weight.
[0006]
  The present invention has been made on the basis of the above knowledge, and includes an inner layer and an outer layer made mainly from pulp and a heat insulating layer formed of a heat insulating material between the inner layer and the outer layer. In an insulated container,The inner layer and the outer layer are three-dimensionally made, and the heat insulating material is a foamable heat insulating material,A mixed layer in which the pulp and the heat insulating material are mixed is formed between the inner layer or the outer layer and the heat insulating layer, and the inner layer or the outer layer and the heat insulating layer are fixed via the mixed layer. The present invention provides a heat insulating container characterized in that
  Further, the present invention is a method for producing a heat insulating container according to the present invention, wherein the inner layer and the outer layer are individually three-dimensionally made, and the outer surface of the made inner layer or the inner surface of the outer layer is foamed. The manufacturing method of the heat insulation container including the process of coat | covering with an agent, the process of superimposing this inner layer and this outer layer, and the process of making the said foaming agent foam by heating is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. FIG. 1 shows an insulated container for instant cup noodles according to an embodiment of the insulated container of the present invention. In the same figure, the code | symbol 1 has shown the heat insulation container.
[0008]
As shown in FIG. 1, the heat insulating container 1 includes a bottomed cylindrical inner layer 2 and an outer layer 3 made mainly from pulp, and is formed of a heat insulating material between the inner layer 2 and the outer layer 3. A heat insulating layer 4 is provided. In the present specification, the inner layer and the outer layer are three-dimensionally made mainly from pulp, and so-called paperboard is excluded.
[0009]
In the heat insulating container 1, the inner layer 2 and the outer layer 3 and the heat insulating layer 4 are formed with a mixed layer (not shown) in which pulp and a foaming agent are mixed at the boundary between the inner layer 2 and the heat insulating layer 4. Thus, both are firmly fixed and integrated, and at the boundary between the outer layer 3 and the heat insulating layer 4, they are integrated by fusing the foaming agent. In this way, the inner layer 2 and the heat insulating layer 4 are firmly integrated through the mixed layer, so that high heat insulating properties and shape retaining properties can be obtained even when hot water or the like is poured. . In addition, by forming a mixed layer on the inner layer 2 side and reducing the density on the inner layer 2 side in this way, even if the outer layer 3 is densified to increase strength and printing characteristics, the weight of the entire container can be reduced. Can be done.
[0010]
In the heat insulating container of the present invention, the basis weight of the outer layer is 250 to 500 g / m.²Preferably, 300 to 400 g / m²It is more preferable that The basis weight of the outer layer is 250 g / m²If it is less than 500 g / m, the compressive strength and drop strength in the vertical and horizontal directions of the container will be insufficient.²If it exceeds 1, sufficient strength can be obtained, but the weight of the container becomes heavier and the time required for papermaking and drying becomes longer and the productivity is lowered. The basis weight of the outer layer can be measured by the measurement method of Examples described later.
[0011]
Further, the density of the outer layer is 0.6 to 1.2 g / cm in that the strength of the outer layer is sufficiently drawn to reduce the weight and obtain the smoothness of the surface.^ThreePreferably, 0.8 to 1.0 g / cm^ThreeIt is more preferable that The density of the outer layer can be measured by the method of Examples described later.
[0012]
The thickness of the outer layer is preferably 0.2 to 0.85 mm, more preferably 0.3 to 0.6 mm in terms of shape retention, compressive strength, and shortening of papermaking / drying time. The thickness of the outer layer can be measured by the method of Examples described later.
[0013]
In the heat insulating container of the present invention, the basis weight of the inner layer is 100 to 400 g / m.²Preferably, 150 to 350 g / m²It is preferable that The basis weight of the inner layer is 100 g / m²If it is less than that, the heat insulating material is exposed on the inner surface, or cracks are generated in the inner layer due to vacuum pressure when the surface of the inner layer is covered with a resin film with a skin pack. 400g / m²If it exceeds, sufficient strength can be obtained, but as in the outer layer, the weight of the container increases and the productivity also decreases. The basis weight of the inner layer can be measured by the method of Examples described later.
[0014]
Further, the density of the inner layer is 0.4 to 0.8 g / cm in terms of surface smoothness, surface strength, shape retention, paper dust prevention and cushioning properties at the time of stacking, and securing strength at the time of skin packing.^ThreePreferably, 0.5 to 0.8 g / cm^ThreeIt is more preferable that In addition, the density of the inner layer can be measured by the method of Examples described later.
Further, the thickness of the inner layer is preferably 0.10 to 1.0 mm, more preferably 0.18 to 0.7 mm, in terms of papermaking stability, shortening of papermaking / drying time, and securing of strength. . Thickness can be measured by the method of the below-mentioned Example.
[0015]
It is preferable that the density of the inner layer is not more than the density of the outer layer. Moreover, it is preferable that the basic weight of the said inner layer is below the basic weight of the said outer layer. When the density of the outer layer is smaller than the density of the inner layer or the basis weight of the outer layer is smaller than the basis weight of the inner layer, the strength against an external load is reduced, and thus buckling is likely to occur. Further, since the outer layer is easily deformed when the container is gripped, the heat insulating layer becomes thin and the heat insulating property is lowered.
[0016]
The inner layer and the outer layer are made mainly from pulp, and may be composed only of pulp fibers. In addition, the pulp fibers include inorganic substances such as talc and kaolinite, and inorganic fibers such as glass fibers and carbon fibers. Other components such as powders or fibers of thermoplastic synthetic resins such as polyolefin, non-wood or vegetable fibers, and polysaccharides can also be contained. The blending amount of these other components is preferably 1 to 70% by weight, particularly 5 to 50% by weight, based on the total amount of pulp fibers and other components. Further, the inner layer 2 and the outer layer 3 may contain a fiber dispersant, a forming aid, a color pigment, a coloring aid, and the like that are appropriately added during the paper making process.
[0017]
The thickness of the heat insulating layer is preferably 0.4 to 3 mm, more preferably 0.5 to 2.0 mm, from the viewpoint of being thin and excellent in heat insulating properties. Here, the thickness of a heat insulation layer means the thickness containing the said mixed layer, and can be measured by the method of the below-mentioned Example.
[0018]
In the present invention, the density of the heat insulation layer is 0.01 to 0.15 g / cm from the viewpoint of being lightweight and excellent in heat insulation.^ThreePreferably, 0.02-0.1 g / cm^ThreeIt is more preferable that Here, the density of a heat insulation layer means the density containing the said mixed layer, and can be measured by the method of the below-mentioned Example.
[0019]
  Heat insulating material forming the heat insulating layerIsFrom the point that a low density layer can be formed uniformly and efficiently, and the inner surface of the inner pulp layer can be locally deformed by foaming pressure to give the inner surface shape.Is used.
  The foaming heat insulating material preferably has a foaming temperature of 100 to 190 ° C., more preferably 110 to 160 ° C., from the viewpoint of suppressing scorching of the inner layer or outer layer pulp fibers due to heat foaming.
  As such a foaming heat insulating material, a foaming agent such as a microcapsule-type foaming agent, a foaming resin, an inorganic foaming agent such as sodium hydrogen carbonate is preferably used, and among these, the foaming ratio can be increased and handled. A microcapsule type foaming agent is preferable from the standpoint of excellent properties, and in particular, a content such as butane or pentane and a skin such as vinylidene chloride or acrylonitrile are preferably used.
[0020]
The heat insulating layer may be composed only of the foaming agent, and the foaming agent is made of the pulp fiber, an inorganic material such as talc or kaolinite, an inorganic fiber such as glass fiber or carbon fiber, or a thermoplastic synthetic resin such as polyolefin. You may contain other components, such as powder or fiber, non-wood or vegetable fiber, and polysaccharides. The blending amounts of these other components are set as appropriate so that the density of the heat insulating layer is not increased, the heat insulating property is not lowered, and the weight of the container is not increased.
[0021]
In the heat insulating container of the present invention, the heat insulating layer is formed between the inner and outer layers and has a predetermined heat insulating performance. The heat insulation performance of the heat insulation container is preferably as the temperature difference between the temperature of the contents and the surface temperature of the container is large, but in the heat insulation container of the present invention, the value of the temperature difference obtained by the measurement method of the examples described later is If it is 20-40 degreeC and surface temperature is 50-65 degreeC, it is favorable, and if the value of a temperature difference is 25-35 degreeC and surface temperature is 55-60 degreeC, it is still more favorable.
[0022]
The heat insulating layer is preferably formed over the entire body and bottom of the container, but from the viewpoint of improving the air permeability when the resin layer is formed by a so-called skin pack, the body and the bottom. May be partially formed.
[0023]
In the heat insulating container of the present invention, the resin layer is for imparting water resistance (leakage resistance), gas barrier properties and the like to the container.
The thickness of the resin layer is preferably 0.02 to 0.10 mm, and more preferably 0.03 to 0.08 mm, in terms of moisture resistance, strength, moldability, and cost. The thickness of the resin layer can be measured by the measurement method of Examples described later.
The material of the resin layer is not particularly limited as long as it can provide the function. For example, polyolefin resin such as polyethylene and polypropylene, polyester resin such as polyethylene terephthalate, polyamide resin such as nylon, A thermoplastic resin film such as a polyvinyl resin such as vinyl chloride and a styrene resin such as polystyrene is used, and among these, a polyolefin resin is particularly preferably used in terms of film production cost, moldability and the like. The resin layer may have either a single layer or a multilayer structure.
[0024]
The heat insulating container 1 has a portion in which the total layer thickness and the total layer density are different depending on the expansion ratio of the foaming agent of the heat insulating layer 4 in the body part 10, and the total layer thickness and the total layer density are It is different in the vertical direction.
[0025]
The heat insulating container 1 has steps (steps) 10a and 10b, and the thickness and density of the body 10 are different from each other with the steps 10a and 10b as a boundary. As the process proceeds, the total layer thickness increases and the total layer density decreases. The level difference 10a is a guide for hot water injection, and the level difference 10b is a level difference (stacking level difference) when the heat insulating containers in an empty state are stacked. In this way, the foaming agent is densified at the portion close to the opening to increase the strength, and the foaming agent is densified from the central portion to the bottom of the body portion 10 serving as the gripping portion to provide high heat insulation. It can be granted. Steps 10 a and 10 b accompanying changes in the total thickness of the body portion 10 are formed in the inner layer 3. In this way, by forming the steps 10a and 10b in the inner layer 3 with the change in the total thickness of the body portion 10, the surface of the outer layer 3 that becomes the outer surface 11 of the container 1 can be formed flat, which is good. The printability can be obtained.
[0026]
In view of making the heat insulating container 1 into a thin container, it is particularly preferable that the total layer thickness (for example, the thickness T2 in FIG. 1) in a portion requiring heat insulation is 0.8 to 5 mm, and 1.3. More preferably, it is -5 mm, and it is most preferable that it is 1.6-4 mm.
[0027]
In the heat insulating container 1, the surface smoothness of at least the inner surface of the inner layer 2 is measured by the following measuring method in terms of adhesion to a resin film, which will be described later, and prevention of pinhole generation in the resin film. In the measured centerline average roughness Ra and maximum height Rmax, Ra is 1 to 20 μm (value measured in accordance with JIS B 0601; the same shall apply hereinafter), and Rmax is 100 μm or less (in accordance with JIS B 0601). It is preferable that Ra is 2 to 10 μm, and Rmax is 80 μm or less.
[0028]
In the heat insulation container 1, the surface smoothness of at least the outer surface of the heat insulation container 1 in the outer layer 3 is the center line average roughness Ra and the maximum measured by the following measurement method in terms of improving printability. In the height Rmax, Ra is preferably 1 to 8 μm and Rmax is preferably 60 μm or less, Ra is preferably 2 to 6 μm, and Rmax is preferably 50 μm or less. On the other hand, the portion of the outer layer 3 that is in contact with the heat insulating layer 4 is made by making the net of the net rough at the time of making the paper from the viewpoint of increasing the contact area between the outer layer 3 and the foamed layer 4 and increasing the bonding strength between them. It is preferable to finish the surface relatively rough.
[0029]
[Measurement method of surface smoothness]
Surfcom 120A (manufactured by Tokyo Seimitsu Co., Ltd.) was used to measure the surface roughness, and the measurement conditions were cut-off: 2.5 mm, measurement length: 10.00 mm, filter: 2CR, measurement magnification: 500, inclination Correction: straight line, polarity: standard.
[0030]
The heat insulating container 1 includes a flange portion 23 in which the inner layer 2 and the outer layer 3 are joined to the periphery of the opening 12 without the heat insulating layer 4 interposed therebetween. Thus, by joining the inner layer 2 and the outer layer 3 without the heat insulating layer 4, the flange portion 23 can be made thin and strong, and the subsequent processing can be easily performed. Moreover, since there is no foaming agent in the flange part 23, there is no worry of mistaking the foaming agent.
[0031]
The heat insulating container 1 is covered with the resin layer 5 up to the back surface of the flange portion 23. Accordingly, it is possible to prevent water from entering from the joining end of the flange 23 which is the joining end of the inner / outer layers 2 and 3, and to prevent damage to the container from the joining end. Further, the mouth feel of the flange 23 when the mouth is attached to the container 1 can be improved.
[0032]
Next, the manufacturing method of the heat insulation container 1 is demonstrated, referring drawings.
[0033]
In the manufacturing method of the heat insulating container 1, first, the inner layer 2 and the outer layer 3 are individually made. Each layer can be made using a set of production dies consisting of a male mold and a female mold. The male mold has, for example, a paper-making part having a desired shape on the outer surface and a gas-liquid flow passage leading to the outer surface and a predetermined opening and wire diameter covering the paper-making part. The one provided with a resin net is used. The male papermaking part used for papermaking is made of an elastic body such as heat-resistant and corrosion-resistant rubber. By using a mold having a papermaking portion formed of an elastic body in this way, a molded body having a complicated surface shape and a deep drawn portion can be formed. On the other hand, for the female mold, a concave metal mold having an inner surface corresponding to the male papermaking portion is used. In addition, since the female mold can be dried in addition to dehydration, a female mold having a heating means is used.
[0034]
For example, as shown in FIGS. 2 (a) and 2 (c), the inner layer 2 and the outer layer 3 have the male mold 30 immersed in the pool P3 and the male mold 20 immersed in the pool P2, with the slurry corresponding to each layer. Then, the slurry is sucked through the gas-liquid flow passage (not shown), and pulp fibers are made with the net (not shown), so that the outer surface of each male net is made wet. The
[0035]
The slurry used for forming each layer is preferably composed of only pulp fibers and water. In addition to pulp fibers and water, inorganic substances such as talc and kaolinite, inorganic fibers such as glass fibers and carbon fibers, thermoplastic synthetic resin powders or fibers such as polyolefins, non-wood or vegetable fibers, polysaccharides, etc. It may contain components. The blending amount of these components is preferably 1 to 70% by weight, particularly 5 to 50% by weight, based on the total amount of pulp fibers and the components.
A pulp fiber dispersant, a molding aid, a coloring agent, a coloring aid, and the like can be appropriately added to the slurry. Moreover, a sizing agent, a pigment, a fixing agent and the like can be appropriately added to the slurry. In particular, by adding a sizing material, when the outer layer dried to a predetermined moisture content and the wet inner layer are integrated, the outer layer can be prevented from absorbing moisture in the inner layer, It is possible to prevent appearance defects such as stains from occurring on the outer surface.
[0036]
Since the pulp fibers are present in a rough state on the surface of the inner layer 2 made by immersing the male mold 20 in the pulp slurry in this way, when the outer surface of the inner layer is subsequently coated with a foaming agent, The foaming agent and the pulp fiber are easily entangled. The water content of the inner layer 2 is preferably 90 to 60%, more preferably 85 to 70%, from the viewpoint that the foaming agent and the pulp fiber can be entangled and a mixed layer can be easily formed.
[0037]
The outer layer 3 is dried in advance and densified before being overlapped with the inner layer from the viewpoint of efficiently foaming the foaming agent to form the heat insulating layer 4. Specifically, after papermaking for a predetermined time, the male mold 30 is pulled up from the slurry and is brought into contact with a metal female mold 31 corresponding to the male mold 30 as shown in FIG. The female mold 31 is preferably one having no exhaust holes on the inner surface so as not to leave behind on the outer surface of the outer layer 3, but if it is desired to shorten the drying time, one having an exhaust hole is used. It can also be used. Then, the wet outer layer 3 is pressed by the paper making part of the male mold 30 to perform dehydration, and the female mold 31 is heated by its heating means (not shown), and the outer layer 3 is dried to be densified. When the outer layer 3 is dehydrated and dried, moisture (water and steam) in the outer layer 3 is sucked through the gas-liquid passage of the male mold 30 and drained outside.
The pressing force during dehydration / drying of the outer layer 3 is preferably 0.2 to 3 MPa, and more preferably 0.3 to 1.5 MPa, from the viewpoint of increasing the dehydration efficiency and increasing the density.
Further, the mold temperature (temperature of the female mold 31) when the outer layer 3 is dried is preferably 150 to 230 ° C, and more preferably 170 to 220 ° C in terms of prevention of scorching due to drying, drying efficiency, and the like. More preferred.
After the outer layer 3 is dehydrated and dried, the outer layer 3 is transferred from the male mold 30 to the female mold 31. After the delivery is completed, the male mold 30 is retracted.
[0038]
While increasing the density of the outer layer 3 as described above, the outer surface of the inner layer 2 is covered with a foaming agent. For example, as shown in FIG. 2 (d), the male mold 20 made of the inner layer 2 is immersed in a pool P containing a liquid containing a foaming agent (a dispersion or solution of the foaming agent). The liquid can be impregnated on the outer surface of the inner layer 2.
[0039]
The amount of the foaming agent is preferably 1 to 20% by weight with respect to the total weight of the heat insulating container, from the viewpoint of making the heat insulating layer at the predetermined density and thickness, production cost, and the like. More preferably, it is% by weight.
[0040]
Next, the inner layer 2 and the outer layer 3 are overlapped so that the heat insulating layer is located between the inner layer 2 and the outer layer 3. That is, as shown in FIG. 2 (e), the inner layer 2 impregnated with the foaming agent is superposed from above the dehydrated and dried outer layer 3 disposed in the female mold 31. At this time, the inner layer 2 is not removed from the male mold 20, and the male mold 20 is butted against the female mold 31 as it is. Then, the inner layer 2 and the outer layer 3 are brought into close contact with each other while dewatering by pressing the wet inner layer 2 with the papermaking portion of the male mold 20. Thereafter, the compressed air is purged through the gas-liquid flow passage in the male mold 21, and the inner layer 2 is transferred from the male mold 20 to the female mold 31. After delivering the inner layer 3, the male mold 20 is retracted.
[0041]
  Next, as shown in FIG. 2 (f), a metal male mold 21 having a predetermined clearance C corresponding to a change in the thickness of all layers with the steps 10a and 10b of the heat insulating container 1 as a boundary is disposed and the female Press against the mold 31. Similar to the male mold 20, the male mold 21 is provided with a gas-liquid flow passage (not shown), and is provided with a heating means (not shown). Then, the male mold 21 and the female mold 31 are heated by the respective heating means, and the foaming agent impregnated in the inner layer 2 is foamed to reduce the density of the heat insulating layer 4. At this time, a mixed layer in which pulp and a foaming agent (heat insulating material) are mixed is formed between the inner layer 2 and the heat insulating layer 4, and both are firmly fixed and firmly integrated, and the heat insulating layer 4 and the outer layer 3 are combined. TogaBy fusing the foaming agentThe container body and the bottom are integrally formed as a whole by being fixed.
[0042]
When the foaming agent foams to a predetermined expansion ratio and the inner layer 2 is dried to a predetermined moisture content, the heating and drying are finished. Then, the heat insulating container (semi-finished product) formed by opening the male and female molds 21 and 31 is removed.
[0043]
Next, the resin layer 5 is formed so as to cover the inner surface of the inner layer 2 and the joint end portion of the flange portion 23. The resin layer 5 can be formed by a conventional method such as vacuum forming. In the case of vacuum forming, for example, as shown in FIG. 3A, the vacuum suction path 60 and the band heater are almost the same size as the female 31 (see FIG. 2) used in the dehydration / drying process of the outer layer 3. A semi-finished heat insulating container is set in the mold 6 using the vacuum forming mold 6 provided with 61, and a resin film 50 is set so as to close the opening of the container. Then, the resin film 50 is softened and pushed into the mold by bringing the plug 7 provided with the heater 70 into contact with the resin film 50 from above, while using the air permeability of the container to bring the inside of the container through the vacuum suction path 60. Is evacuated to bring the resin film 50 into close contact with the inner surface of the inner layer 3. Further, as shown in FIG. 3B, a predetermined clearance is provided between a portion 62 facing the lower surface of the flange 23 in the vacuum forming die 6 and the flange 23, and the suction of the vacuum suction path 60 is also provided to the portion 62. By providing the opening, the resin layer 5 can be brought into close contact with the lower surface of the flange 23, whereby the joining end portion of the flange 23 can be reliably covered with the resin film 50. Then, the resin film 50 is trimmed to complete the manufacture.
[0044]
As described above, in the heat insulating container 1 of the present embodiment, a mixed layer in which pulp and a foaming agent are mixed is formed between the inner layer 2 and the heat insulating layer 4, and the inner layer 2 and the heat insulating layer 4 are formed by the mixed layer. Since it is fixed and integrated, sufficient mechanical strength can be obtained without increasing the basis weight of the inner layer 2 and the outer layer 3, and it is thin, lightweight, and has excellent mechanical strength and heat insulation. It is a container. In particular, since the mixed layer is formed on the inner layer 2 side, the density of the outer layer can be increased by that amount, and the strength, printing characteristics, surface properties, and the like can be increased.
[0045]
Moreover, since the surface of the heat insulating container 1 is smooth and there are no joints or the like on the inner surface and the outer surface, the printability is good and the adhesion of the resin film is also good.
[0046]
In addition, the total layer thickness and total layer density are different in the vertical direction of the body portion depending on the expansion ratio of the foaming agent, and the strength is increased by suppressing the expansion ratio in the vicinity of the flange 23 that does not require much heat insulation. From the center to the bottom of the body, which requires heat insulation, the foaming ratio is increased to increase the heat insulation, and this is an excellent container having heat insulation and strength at the necessary locations.
[0047]
The present invention is not limited to the above-described embodiment, and can be changed without departing from the spirit of the present invention.
When the heat insulating container of the present invention is a cup-shaped container, as in the heat insulating container 1 of the above-described embodiment, the body portion (grip) has different thicknesses and total densities depending on the foaming ratio of the foaming agent. The portion where the total layer thickness and the total density are different depending on the foaming ratio of the foaming agent can be appropriately set according to the shape of the container. For example, the shape of the container is a dish shape. In the case of this container, it can be formed in other parts such as the trunk and the bottom. Moreover, although it is preferable to form a stack in the trunk portion, the stack can be omitted if necessary.
[0048]
  In the heat insulating container of the present invention, it is preferable to form a mixed layer on the inner layer side so as to fix the inner layer and the heat insulating layer as in the heat insulating container 1 of the above embodiment.Thermal insulation layerCan be formed on the outer layer side so as to be fixed, or can be formed on both sides so that the inner layer and the outer layer and the heat insulating layer are fixed.
[0049]
It goes without saying that the heat insulating container of the present invention can be applied to containers of various shapes such as a bowl-shaped container, a bottle-shaped container, a dish-shaped container, and a tray container in addition to the container having the flange.
Moreover, since the heat insulation container of this invention has heat insulation and it is hard to produce dew condensation etc. on the surface, it cannot be overemphasized that it can be used also as a container of cool food-drinks.
[0050]
Further, the method of coating the outer surface of the inner layer with a foaming agent is preferably performed by immersing the outer surface of the inner layer in a liquid containing a foaming agent as described above and impregnating the outer surface of the inner layer with the liquid. However, the liquid can be coated by spray coating or the like.
[0051]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
Insulated containers were prepared as in Examples 1 and 2 and Comparative Examples 1 and 2, and the weight thereof was measured, and the strength, heat insulating properties, and peelability between the inner layer and the heat insulating layer were evaluated as follows. . Moreover, each weight, thickness, density, and basic weight of the outer layer and inner layer of the obtained heat insulation container, and the thickness and density of the heat insulation layer were measured by the following measuring methods. The results are shown in Table 1.
[0052]
[Example 1]
A heat insulating container having the form shown in FIG. 1 and having the following dimensions and shape was produced as follows.
[0053]
<Container shape>
Height H: 110mm
Opening inner diameter φ1: 88mm
Bottom outer diameter φ2: 70mm
Body center thickness T2: 1.5 mm
Bottom thickness T4: 1.0 mm
Flange thickness T5: 0.8mm
[0054]
<Inner / outer papermaking>
A male mold provided with a silicone rubber papermaking part corresponding to each inner and outer layer of the heat insulating container and a nylon net (50 mesh, wire diameter 100 μm) covering the papermaking part is immersed in a slurry having the following composition to each layer. Formed.
Slurry for outer layer;
Pulp slurry: Pulp fiber (virgin pulp: imitation waste paper = 3: 7 (weight ratio), pulp slurry concentration 0.5% by weight)
Sizing agent (2% by weight of pulp)
Slurry for inner layer;
Pulp slurry: Pulp fiber (virgin pulp: imitation waste paper = 3: 7 (weight ratio), pulp slurry concentration 0.5% by weight)
Sizing agent (2% by weight of pulp)
[0055]
<Dehydration and drying conditions for outer layer>
The outer layer was placed between the female mold corresponding to the male mold, and dehydrated and dried under pressure under the following conditions.
Mold temperature: 160 ° C
Pressing force: 0.4 MPa (90 seconds)
[0056]
<Coating with foaming agent on outer surface of inner layer>
The inner layer (water content 84%) was immersed in a foaming agent-containing liquid having the following composition, and the outer surface of the body part of the inner layer was impregnated with the foaming agent.
Foaming agent-containing liquid;
Water containing 1 wt% foaming agent (Matsumoto Microsphere-F793 manufactured by Matsumoto Yushi Seiyaku Co., Ltd .: foaming temperature of 110 to 170 ° C.) (vs. 5% by weight with respect to the total weight of the molded product)
[0057]
<Heating and drying conditions>
After the inner and outer layers were superposed, they were dried under the following mold temperature and pressure to foam the foaming agent and to integrate both layers.
Mold temperature: 160 ° C
Pressing load: 11760N (60 seconds)
Flange pressing force: 1.5 MPa
Male mold temperature: 140 ° C
[0058]
<Formation of resin layer>
It arrange | positioned so that the inner layer of the following resin film might contact the inner layer of a container, and it laminated | stacked on the following molding conditions.
Resin film;
Outer layer / inner layer = high density polyethylene / low density polyethylene
Resin layer thickness: 150 μm
Molding condition;
Vacuum forming machine: PLAVAC-FE36PHS, manufactured by Sanwa Kogyo Co., Ltd.
Film heating method: Infrared heater (space between heater and resin film 110mm)
Film heating temperature: 250 ° C (molding machine display temperature)
Film heating time: 35 seconds
Plug dimensions: 60mm diameter x 110mm length
Plug material: Aluminum (Teflon processing on the surface)
Plug temperature: 115 ° C (plug actual surface temperature)
Vacuum forming mold: mouth hole diameter φ88mm, bottom diameter φ70mm, height 110mm
Mold temperature for vacuum forming: 115 ° C (actual surface temperature inside the mold)
Molding time: 15 seconds
[0059]
[Example 2]
It was produced in the same manner as in Example 1 except that the inner layer was made lighter than the outer layer.
[0060]
[Comparative Example 1]
It was produced in the same manner as in Example 1 except that no foaming agent was used for the heat insulating layer.
[0061]
[Comparative Example 2]
It was produced in the same manner as in Example 1 except that a slurry composed of water and a foaming agent was applied to the inner surface of the dried outer layer pulp to form a heat insulating layer composed of only the foaming agent between the outer layer and the inner layer.
[0062]
[Measurement of thickness of outer layer, inner layer and heat insulating layer]
Outer layer: The outer layer thickness is obtained by cutting out a specimen having a predetermined size and shape (about φ40 mm disk shape) from the body of the resulting molded body, separating only the outer layer from the specimen, and measuring its thickness and weight. Basis weight and density were calculated.
Inner layer: Only the inner layer was separated from the specimen, and the thickness, basis weight and density of the inner layer were calculated by measuring the thickness and weight. When a mixed layer was formed between the inner layer and the heat insulating layer, the thickness and basis weight and density of the inner layer were calculated by measuring the thickness and weight after removing the mixed layer.
Heat insulation layer: The thickness (including the mixed layer) and density of the heat insulation layer were calculated by subtracting the thickness and weight of the resin layer, outer layer and inner layer from the thickness and weight of the specimen.
Resin layer: For the resin layer, only the resin film was separated from the specimen and the thickness thereof was measured.
[0063]
(Measurement of compressive strength)
Lateral load (gripping strength): The obtained container was set horizontally on a compression strength measuring machine (Orientec Co., Ltd., RTA-500), the crosshead speed was set to 20 mm / min, and the container was It calculated | required from the load when a 10-mm displacement generate | occur | produced in the part.
Longitudinal load: The obtained container was set vertically on the compressive strength measuring machine, and the crosshead speed was set to 20 mm / min. In addition, when the yield due to buckling of the corner of the container bottom appears in the load-displacement curve, the load at the time of yielding (longitudinal load (1) in Table 1) and the load when the body buckles (maximum) Load: The load at two locations of the longitudinal load (2) in Table 1 was measured.
[0064]
〔Thermal insulation properties〕
Pour hot water of 95-100 ° C into the obtained container, measure the temperature of the hot water in the container after 3 minutes and the temperature of the outer surface of the container with a contact thermometer, and the temperature of the hot water and the temperature of the outer surface of the container And the temperature difference was obtained.
[0065]
[Peelability]
The state of the inner surface of the container and the cross section of the container when a predetermined lateral load was applied to the obtained container was observed visually or with a microscope.
[0066]
[Table 1]

[0067]
As shown in Table 1, the container (Examples 1 and 2) in which the mixed layer is formed between the inner layer and the heat insulating layer is thin and lightweight, has a desired mechanical strength and heat insulating property, and is deformed. It was confirmed that no delamination occurred. On the other hand, in a container that does not have a heat insulating material (Comparative Example 1) and a container that has a heat insulating layer made of a heat insulating material but does not have a mixed layer (Comparative Example 2), Deformation load (corresponding to gripping strength) when placed is not sufficiently obtained (Comparative Example 1), and when the mixed layer is not formed, delamination occurs and the inner surface of the container is wrinkled or cracked. It was confirmed that it occurred.
[0068]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the heat insulation container which is thin, lightweight, and has both buckling strength and heat insulation is provided.
[Brief description of the drawings]
FIG. 1 is a schematic half sectional view showing an embodiment of a heat insulating container of the present invention.
FIG. 2 is a schematic diagram showing a part of the manufacturing process of the heat insulating container of the present invention, (a) is a diagram showing a paper making process of the outer layer, (b) is a diagram showing a dehydration / drying process of the outer layer, (c) is a diagram showing a paper making process of the inner layer, (d) is a diagram showing a process of coating the outer surface of the inner layer with a foaming agent, (e) is a diagram showing a superimposing process of the inner layer and the outer layer, (f) FIG. 4 is a diagram showing a drying process.
FIG. 3 is a schematic view showing a resin layer forming step in the method for manufacturing a heat insulating container of the present invention, (a) is a schematic cross-sectional view showing a state where the container is set in a vacuum forming machine, and (b) It is an expanded sectional view which shows the contact | adherence state of the resin film in the flange part of (a).
[Explanation of symbols]
1 Insulated container
2 Inner layer
3 outer layer
4 Insulation layer
5 Resin layer

Claims (7)

In a heat insulating container having an inner layer and an outer layer made mainly from pulp and having a heat insulating layer formed of a heat insulating material between the inner layer and the outer layer, the inner layer and the outer layer are made three-dimensionally. The heat insulating material is a foamable heat insulating material, and a mixed layer in which the pulp and the heat insulating material are mixed is formed between the inner layer or the outer layer and the heat insulating layer, and the mixed layer The heat insulating container, wherein the inner layer or the outer layer and the heat insulating layer are fixed to each other through a gap. The mixed layer is formed between the inner layer and the heat insulating layer, and the outer layer and the heat insulating layer are fixed by fusing the foaming agent of the heat insulating layer, or between the outer layer and the heat insulating layer. The heat insulating container according to claim 1, wherein the mixed layer is formed and the inner layer and the heat insulating layer are fixed to each other by fusion of a foaming agent of the heat insulating layer .   The heat insulation container according to claim 1 or 2, wherein the density of the inner layer is equal to or less than the density of the outer layer, or the basis weight of the inner layer is equal to or less than the basis weight of the outer layer. The basis weight of the inner layer is 100 to 400 g / m ² , the basis weight of the outer layer is 250 to 500 g / m ² , the density of the inner layer is 0.4 to 0.8 g / cm ³ , and the density of the outer layer Is 0.6-1.2 g / cm < ³ >, The heat insulation container in any one of Claims 1-3 . The heat insulation container in any one of Claims 1-4 in which the uneven | corrugated | grooved part or the step part is formed in the inner surface of the said inner layer. The heat insulation container in any one of Claims 1-5 provided with the resin layer which covers the inner surface of the said inner layer. It is a manufacturing method of the heat insulation container of Claim 1, Comprising: The process which forms an inner layer and an outer layer separately three-dimensionally, and coat | covers the outer surface of the made inner layer or the inner surface of this outer layer with a foaming agent The manufacturing method of the heat insulation container including the process, the process of superimposing this inner layer and this outer layer, and the process of making the said foaming agent foam by heating.

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