JP2002321776A - Insulating container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating container which is thin-walled and light in weight, and having both buckling strength and thermal insulating properties. SOLUTION: The insulating container provides an inner layer 2 and an external layer 3, which are sheet-made of mainly a pulp, and provides an insulating layer 4 formed with an insulating material between the inner layer 2 and the outer layer 3. A mixing layer, wherein the pulp and the insulating material are mixed, is formed between the inner layer 2 and the insulating layer 4, and the inner layer 2 and the insulating layer 4 are fastened via the mixing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating container which is thin, lightweight, and excellent in buckling strength and heat insulation.

[0002]

2. Description of the Related Art The prior art relating to a pulp mold heat-insulating container having an inner layer and an outer layer and an insulating layer between the inner layer and the outer layer includes, for example, JP-A-11-301753
An insulated container described in Japanese Unexamined Patent Publication (Kokai) No. HEI 9-203 is known. This heat insulating container made of pulp mold has a heat insulating space formed by providing a gap between an inner layer and an outer layer made of pulp mold.
By the way, in this heat insulating container of the prior art, 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 the density of the inner layer and the outer layer. It had to be thick, and the weight of the whole container had to be heavy.

[0003] On the other hand, Japanese Patent Application Laid-Open No. 2000-109123 discloses a container in which an inner layer made of a paper base material and an outer layer are used, and an intermediate layer made of a foamed material containing pulp is bonded with an adhesive therebetween. It has been disclosed. However, since a foaming agent containing this pulp cannot obtain a high expansion coefficient even when foamed, a large amount of the foaming agent must be used in order to obtain a desired heat insulating property. I had no choice. Also, in this container, if the thickness of the base material is reduced to reduce the weight of the container, the adhesive penetrates into the base material, and the base material becomes inconveniently discolored or deformed as if it were bulky. There was a problem that an adhesive for obtaining sufficient adhesiveness with the layer could not be applied, and the substrate and the intermediate layer were easily peeled off.

Accordingly, an object of the present invention is to provide a thin, lightweight,
Another object of the present invention is to provide a heat insulating container having both buckling strength and heat insulating properties.

[0005]

Means for Solving the Problems The present inventors have provided 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 combined with the pulp. It has been found that by fixing through a mixed layer in which the above-mentioned heat insulating material is mixed, a heat insulating container having desired buckling strength and heat insulating properties with a reduced thickness and weight can be obtained.

The present invention has been made based on the above-mentioned findings, and has an inner layer and an outer layer made mainly of pulp, and a heat insulating layer formed of a heat insulating material between the inner layer and the outer layer. In the heat insulating container provided, a mixed layer in which the pulp and the heat insulating material are mixed between the inner layer or the outer layer and the heat insulating layer is formed, and the inner layer or the outer layer is interposed through the mixed layer. An object of the present invention is to provide a heat insulating container to which the heat insulating layer is fixed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 one embodiment of the insulated container of the present invention. In the figure, reference numeral 1 indicates a heat insulating container.

As shown in FIG. 1, a heat insulating container 1 has a bottomed cylindrical inner layer 2 and an outer layer 3 made mainly of pulp, and a heat insulating material is provided between the inner layer 2 and the outer layer 3. The heat insulating layer 4 is provided. In the present specification, the inner layer and the outer layer are three-dimensionally formed mainly of pulp, and exclude so-called paperboard ones.

In the heat insulating container 1, the inner layer 2 and the outer layer 3
At the boundary between the inner layer 2 and the heat insulating layer 4, a mixed layer (not shown) in which pulp and a foaming agent are mixed is formed, and the two layers are firmly fixed and integrated by the mixed layer. At the boundary between the outer layer 3 and the heat insulating layer 4, they are integrated by fusion of a foaming agent. In this way, the inner layer 2 and the heat-insulating layer 4 are firmly integrated via 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. . Further, by forming the mixed layer on the inner layer 2 side and reducing the density on the inner layer 2 side,
Even if the strength and printing characteristics are increased by increasing the density of the outer layer 3, the weight of the entire container can be reduced.

In the heat insulating container of the present invention, the basis weight of the outer layer is preferably from 250 to 500 g / m ² ,
It is more preferable that the amount be from 00 to 400 g / m ² . If the basis weight of the outer layer is less than 250 g / m ² , the compressive strength and the drop strength in the vertical and horizontal directions of the container become insufficient, and
If it exceeds 0 g / m ² , sufficient strength can be obtained, but the weight of the container is increased, and the time required for papermaking and drying is increased, and the productivity is reduced. The basis weight of the outer layer can be measured by the measuring method described in Examples below.

The density of the outer layer is preferably 0.6 to 1.2 g / cm ^{3 from the} viewpoint that the strength of the outer layer can be sufficiently obtained to reduce the weight and to obtain a smooth surface. More preferably, it is 0.8 to 1.0 g / cm ³ . The density of the outer layer can be measured by the method described in Examples described later.

[0012] The thickness of the outer layer is determined by the shape retention, compressive strength,
0.2-0.85m in terms of shortening papermaking and drying time
m, more preferably 0.3 to 0.6 mm. The thickness of the outer layer can be measured by the method described in Examples below.

The heat insulating container of the present invention has an inner layer having a basis weight of 100.
To 400 g / m ² , preferably 150 to 35 g / m ^2.
It is preferably 0 g / m ² . Inner layer basis weight is 100
When it is less than g / m ² , the heat insulating material is exposed on the inner surface, and when the surface of the inner layer is covered with the resin film by the skin pack, cracks are generated in the inner layer by vacuum pressure. 4
If it exceeds 00 g / m ² , sufficient strength can be obtained,
As in the case of the outer layer, the weight of the container is increased and the productivity is reduced. The grammage of the inner layer can be measured by the method described in Examples below.

The density of the inner layer is determined in terms of surface smoothness, surface strength, shape retention, paper dust prevention and cushioning during stacking, and securing strength during skin pack.
It is preferably 0.4 to 0.8 g / cm ³ ,
More preferably, it is 5 to 0.8 g / cm ³ . Note that the density of the inner layer can be measured by the method described in Examples below. In addition, the thickness of the inner layer is 0.10 to 0.10 in terms of papermaking stability, reduction of papermaking / drying time, and strength.
1.0 mm, preferably 0.18 to 0.7 m
m is more preferable. The thickness can be measured by the method described in Examples below.

Preferably, the density of the inner layer is equal to or less than the density of the outer layer. Further, the basis weight of the inner layer is preferably equal to or less than the basis weight of the 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, so that buckling is likely to occur. Further, when the container is gripped, the outer layer is easily deformed, so that the heat insulating layer is thinned and the heat insulating property is reduced.

The inner layer and the outer layer are made mainly of pulp and may be made of only pulp fiber. Alternatively, the pulp fiber may be made of an inorganic substance such as talc or kaolinite, glass fiber or carbon fiber. And other components such as inorganic fibers, thermoplastic synthetic resin powders or fibers such as polyolefins, non-wood or vegetable fibers, and polysaccharides. The compounding amount of these other components is preferably 1 to 70% by weight, particularly preferably 5 to 50% by weight based on the total amount of the pulp fiber and the other components. Also,
The inner layer 2 and the outer layer 3 may contain a fiber dispersant, a molding aid, a coloring pigment, a coloring aid, and the like that are appropriately added during the papermaking.

The thickness of the heat-insulating layer is preferably from 0.4 to 3 mm, more preferably from 0.5 to 2.0 mm, from the viewpoint of achieving a thin and excellent heat-insulating property. Here, the thickness of the heat insulating layer refers to the thickness including the mixed layer, and can be measured by the method described in Examples below.

In the present invention, the density of the heat insulating layer is from 0.01 to 0.
It is preferably 15 g / cm ³ and 0.02 to 0.1 g / cm ³ .
More preferably, it is 1 g / cm ³ . Here, the density of the heat insulating layer refers to the density including the mixed layer, and can be measured by the method described in Examples below.

The heat-insulating material forming the heat-insulating layer is not particularly limited, but it can form a low-density layer uniformly and efficiently.
It is preferable to use a foamable heat insulating material from the viewpoint that the inner surface of the inner pulp layer can be locally deformed by the foaming pressure to impart an inner surface shape. The foaming heat-insulating material preferably has a foaming temperature of 100 to 190 ° C., from the viewpoint of suppressing scorching or the like of the pulp fibers of the inner layer or the outer layer due to the heat foaming.
Those at 160 ° C. are more preferred. As such a foaming heat insulating material, a microcapsule-type foaming agent, a foaming resin, a foaming agent such as an inorganic foaming agent such as sodium hydrogen carbonate and the like are preferably used. A microcapsule-type foaming agent is preferred in terms of excellent properties and the like, and in particular, those whose contents are butane, pentane, and the like and whose outer skin is vinylidene chloride, acrylonitrile, and the like are preferably used.

The heat-insulating layer may be composed solely of the foaming agent. The foaming agent may be formed of an inorganic material such as pulp fiber, talc or kaolinite, an inorganic fiber such as glass fiber or carbon fiber, or a thermoplastic material such as polyolefin. Other components such as synthetic resin powder or fiber, non-wood or vegetable fiber, and polysaccharides may be contained. The amount of these other components increases the density of the heat-insulating layer, lowers the heat-insulating properties,
Set appropriately so as not to increase the weight of the container.

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-insulating container is preferably as large as the temperature difference between the temperature of the contents and the surface temperature of the container, but in the heat-insulating container of the present invention, the value of the temperature difference obtained by the measurement method of the example described later is 20-40 ° C, surface temperature 5
0-65 ° C is good, and the value of the temperature difference is 25-3.
It is even better if the temperature is 5 ° C and the surface temperature is 55-60 ° C.

The heat insulating layer is preferably formed over the entire body and bottom of the container. However, from the viewpoint of improving the air permeability when the resin layer is formed by a so-called skin pack, the heat insulating layer is preferably made of a resin. It may be partially formed on the part and the bottom.

In the heat insulating container of the present invention, the resin layer is for imparting water resistance (leakage prevention), gas barrier properties and the like to the container. The thickness of the resin layer is
0.02 to 0.10 mm in terms of moldability and cost
Is preferably, and more preferably 0.03 to 0.08 mm. The thickness of the resin layer can be measured by a measurement method described in Examples below. The resin layer is not particularly limited in its material as long as it can impart the function, for example, a polyolefin resin such as polyethylene or polypropylene, a polyester resin such as polyethylene terephthalate, a polyamide resin such as nylon,
Thermoplastic resin films such as polyvinyl resins such as polyvinyl chloride and styrene resins such as polystyrene are used, and among these, polyolefin resins are particularly preferably used in view of film production cost, moldability and the like. Further, the resin layer may have a single layer structure or a multilayer structure.

The heat-insulating container 1 is provided with a body 1 having different thicknesses and different densities depending on the expansion ratio of the foaming agent of the heat-insulating layer 4.
0, and the total layer thickness and the total layer density are different in the vertical direction of the body.

The heat insulating container 1 is provided with steps (steps) 10a, 10a.
b, the entire layer thickness and the total layer density of the body 10 are different from each other at the steps 10a and 10b. Density is low. The step 10a indicates an indication of hot water injection, and the step 10b is a step (stacking step) when stacking the empty heat-insulating containers. As described above, the density is increased by increasing the density of the foaming agent in the portion close to the opening, and the density of the foaming agent is reduced from the central portion to the bottom of the body portion 10 serving as a gripping portion, thereby achieving high heat insulation. It can be given. Body 1
The steps 10 a and 10 b accompanying the change in the total thickness of 0 are formed in the inner layer 3. By forming the steps 10a and 10b in the inner layer 3 according to the change in the total thickness of the body 10 in this manner, the surface of the outer layer 3 that becomes the outer surface 11 of the container 1 can be formed flat, which is favorable. Printability.

From the viewpoint of making the heat-insulating container 1 a thin container, it is particularly preferable that the total layer thickness (for example, the thickness T2 in FIG. 1) in the portion requiring heat insulation is 0.8 to 5 mm, It is more preferably from 1.3 to 5 mm, most preferably from 1.6 to 4 mm.

In the heat insulating container 1, the surface smoothness of at least a portion of the inner layer 2 which is to be the inner surface of the heat insulating container 1 is as follows:
In terms of adhesion to the resin film described later, prevention of pinholes in the resin film, etc., in the center line average roughness Ra and the maximum height Rmax measured by the following measurement method,
Preferably, Ra is 1 to 20 μm (a value measured according to JIS B 0601; the same applies hereinafter), and Rmax is 100 μm or less (a value measured according to JIS B 0601; the same applies hereinafter). Ra is 2 to 10 μm,
More preferably, Rmax is not more than 80 μm.

In the heat insulating container 1, the surface smoothness of at least a portion of the outer layer 3 which is the outer surface of the heat insulating container 1 is as follows:
From the viewpoint of improving printability, for example, the center line average roughness Ra and the maximum height Rmax measured by the following measurement method are preferably Ra 1 to 8 μm, Rmax 60 μm or less, and Ra 2 ６6 μm, and Rmax is preferably 50 μm or less. On the other hand, from the viewpoint of increasing the contact area between the outer layer 3 and the foam layer 4 and increasing the bonding strength between the outer layer 3 and the foam layer 4, the portion of the outer layer 3 which is in contact with the heat insulating layer 4 is formed by coarsening the net at the time of papermaking. It is preferable to finish the surface relatively coarsely.

[Method of Measuring Surface Smoothness] Surfcom 120A (manufactured by Tokyo Seimitsu Co., Ltd.) was used to measure the surface roughness. The measurement conditions were cutoff: 2.5 mm, measurement length:
10.00mm, filter: 2CR, measurement magnification: 50
0, inclination correction: linear, polarity: standard.

The heat insulating container 1 is provided with a flange 23 on the periphery of the opening 12 to which the inner layer 2 and the outer layer 3 are joined without interposing the heat insulating layer 4. 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. In addition, since the foaming agent does not exist in the flange portion 23, there is no fear that the foaming agent is accidentally throated.

The heat insulating container 1 is covered with the resin layer 5 up to the back surface of the flange portion 23. Thereby, the inner and outer layers 2,
In addition to preventing water from entering from the joint end of the flange 23, which is the joint end of No. 3, damage to the container from the joint end can be prevented. Moreover, the mouth of the flange 23 when the mouth is attached to the container 1 can be made favorable.

Next, a method for manufacturing the heat insulating container 1 will be described with reference to the drawings.

In the method of manufacturing the heat insulating container 1, first,
The inner layer 2 and the outer layer 3 are separately formed. Each layer can be made using a set of production molds consisting of a male mold and a female mold. The male mold has, for example, a papermaking part having a desired shape on the outer surface and a gas-liquid flow passage communicating with the outer surface inside, and a predetermined aperture and wire diameter covering the papermaking part. And a resin net having the same. The male papermaking section used for this papermaking is formed of an elastic body such as heat and corrosion resistant rubber. By using a mold having a paper making section formed of an elastic body in this way, a molded article having a complicated surface shape and a deep drawn portion can be formed. On the other hand, a concave metal mold having an inner surface shape corresponding to the papermaking section of the male mold is used for the female mold. Also,
A female mold having a heating means is used because it can be dried as well as dehydrated.

The inner layer 2 and the outer layer 3 are formed, for example, as shown in FIG.
And (c), after immersing the male mold 30 in the pool P3 and the male mold 20 in the pool P2 filled with the slurry corresponding to each layer, and then through the gas-liquid flow passage (not shown). The slurry is sucked, and pulp fibers are made with the net (not shown), so that the outer surface of each male net is wet-formed.

The slurry used for forming each layer is preferably composed of only pulp fiber 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 and the like. A component may be contained. The compounding amount of these components is preferably 1 to 70% by weight, particularly preferably 5 to 50% by weight based on the total amount of the pulp fiber 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. Further, 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 inner layer in a wet state are integrated, it is possible to prevent the outer layer from absorbing the moisture of the inner layer. This can prevent appearance defects such as spots from occurring on the outer surface of the substrate.

Since the pulp fibers are present in a rough state on the surface of the inner layer 2 made by dipping the male mold 20 in the pulp slurry in this manner, the outer surface of the inner layer is thereafter coated with a foaming agent. At this time, the foaming agent and the pulp fiber tend to be entangled. The water content of the inner layer 2 is preferably 90 to 60% from the viewpoint that the foaming agent and the pulp fiber are entangled with each other and a mixed layer can be easily formed.
% Is more preferable.

The outer layer 3 is preliminarily dried and densified before overlapping with the inner layer from the viewpoint that the foaming agent can be efficiently foamed to form the heat insulating layer 4. Specifically, after papermaking for a predetermined time, the male mold 30 was pulled out of the slurry, and FIG.
As shown in (b), the metal mold 31 is brought into contact with the metal mold 31 corresponding to the male mold 30. As the female mold 31, it is preferable to use one not having an exhaust hole on the inner surface so as not to leave behind on the outer surface of the outer layer 3. However, if it is desired to shorten the drying time, use one having an exhaust hole. It can also be used. And
The papermaking section of the male mold 30 presses the wet outer layer 3 to perform dehydration, and further heats the female mold 31 by its heating means (not shown) to dry the outer layer 3 to increase the density. When the outer layer 3 is dehydrated and dried, the outer layer 3 is passed through the gas-liquid passage of the male mold 30.
Of water (water and steam) and drain to the outside. The pressing force at the time of dehydration / drying of the outer layer 3 is preferably 0.2 to 3 MPa, 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) at the time of drying the outer layer 3 is preferably 150 to 230 ° C. in terms of prevention of scorching due to drying, drying efficiency, and the like.
The temperature is more preferably 70 to 220 ° C. After dehydration and drying of the outer layer 3, 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 evacuated.

As described above, while increasing the density of the outer layer 3, the outer surface of the inner layer 2 is covered with a foaming agent. As shown in FIG. 2 (d), for example, as shown in FIG. 2 (d), the male mold 20 having the inner layer 2 made of paper is immersed in a pool P filled with a liquid containing a foaming agent (a dispersion or a solution of the foaming agent). Then, it can be carried out by impregnating the outer surface of the inner layer 2 with the liquid.

The amount of the foaming agent is determined by adjusting the heat insulating layer to the predetermined density,
From the viewpoints of thickness and production cost, the blending ratio with respect to the total weight of the heat insulating container is preferably 1 to 20% by weight, and more preferably 3 to 10% by weight.

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. 2E, the inner layer 2 impregnated with the foaming agent is superimposed from above the dewatered and dried outer layer 3 arranged in the female mold 31. At this time, the inner layer 2 is not released from the male mold 20, but the male mold 20 is directly butted against the female mold 31. Then, the inner layer 2 and the outer layer 3 are brought into close contact with each other while pressing the wet inner layer 2 with the papermaking section of the male mold 20 to perform dehydration.
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 evacuated.

Next, as shown in FIG. 2 (f), the metal male mold 2 having a predetermined clearance C corresponding to the change in the thickness of all layers at the boundaries between the steps 10a and 10b of the heat insulating container 1.
1 is arranged and pressed against the female mold 31. The male mold 21 is provided with a gas-liquid flow passage (not shown) similarly to the male mold 20, and is provided with a heating means (not shown). Then, the male mold 21 and the female mold 31 are heated by respective heating means, and the foaming agent impregnated in the inner layer 2 is foamed to lower 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 fixed and firmly integrated, and the heat insulating layer 4 and the outer layer 3 are combined. And the container body and bottom are integrally formed as a whole. Further, the flange portions are joined and integrated by the pressing force at the time of drying. It is preferable to use an adhesive for joining the flange portions in order to increase the adhesive strength, and it is particularly preferable to use an adhesive such as starch for a food container. During the drying, the water in the inner layer 2 is discharged to the outside through the gas-liquid flow passage of the male mold 21 as water vapor. The mold temperature at the time of drying is preferably from 140 to 230 ° C. from the viewpoint of keeping the drying efficiency at a high level while keeping the temperature at or above the foaming start temperature and preventing the layers 2 and 3 from being scorched and keeping the drying efficiency high.
It is more preferable that the temperature be within a range of from to 220 ° C.

When the foaming agent has foamed to a predetermined expansion ratio and the inner layer 2 has been dried to a predetermined moisture content, the heating and drying are completed. Then, the male and female molds 21 and 31 are opened, and the heat-insulated container (semi-finished product) formed is released.

Next, the inner surface of the inner layer 2 and the flange 2
The resin layer 5 is formed so as to cover the joint end portion of FIG. The resin layer 5 can be formed by a standard method such as vacuum forming. In the case of vacuum forming, for example, as shown in FIG. 3 (a), a vacuum suction path 60 and a band heater having substantially the same dimensions as the female 31 (see FIG. 2) used in the dehydrating / drying step of the outer layer 3 are used. A semi-finished heat insulating container is set in the vacuum forming die 6 provided with 61, and a resin film 50 is set so as to close the opening of the container. Then, the plug 7 provided with the heater 70 is brought into contact with the resin film 50 from above to soften the resin film 50 and push it into the mold. Is evacuated to bring the resin film 50 into close contact with the inner surface of the inner layer 3. As shown in FIG. 3B, a predetermined clearance is provided between a portion 62 of the vacuum forming die 6 facing the lower surface of the flange 23 and the flange 23, and the vacuum suction path 6 is also provided in the portion 62.
By providing a suction port of “0”, the resin layer 5
3 can be brought into close contact with the lower surface, whereby the joining end of the flange 23 can be reliably covered with the resin film 50. Then, the resin film 50 is trimmed to complete the manufacturing.

As described above, in the heat insulating container 1 of this embodiment, the mixed layer in which the pulp and the foaming agent are mixed is formed between the inner layer 2 and the heat insulating layer 4, and the mixed layer forms the inner layer 2 and the heat insulating layer. Since the layer 4 is fixed and integrated, the inner layer 2
Further, it is an excellent container which can obtain sufficient mechanical strength without increasing the basis weight of the outer layer 3, is thin and lightweight, and has desired mechanical strength and heat insulating properties. 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.

The heat insulating container 1 has a smooth surface,
Since there are no joints or the like on the inner surface and the outer surface, printability is good and adhesion of the resin film is also good.

The total layer thickness and the total layer density vary in the vertical direction of the body in accordance with the expansion ratio of the foaming agent.
In the vicinity of the flange 23 that does not require much heat insulation, the foaming ratio is suppressed to increase the strength, and from the center to the bottom of the body that requires heat insulation, the foaming ratio is increased to increase the heat insulation. It is an excellent container having heat insulating properties and strength at necessary places.

The present invention is not limited to the above embodiment, and can be modified 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 (grip) holds a portion having a different total thickness and a different density according to the expansion ratio of the blowing agent. Part), it is preferable to form a part where the total layer thickness and the total density are different depending on the expansion ratio of the foaming agent,
It can be set appropriately according to the shape of the container, for example,
When the shape of the container is a dish-shaped container, it can be formed on other parts such as a trunk and a bottom. In addition, it is preferable to form a stack on the body, but the stack can be omitted if necessary.

Further, 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.
The mixed layer can be formed on the outer layer side so as to fix the outer layer and the inner layer, or can be formed on both sides so as to fix the inner layer and the outer layer and the heat insulating layer.

It goes without saying that the heat insulating container of the present invention can be applied to containers of various shapes such as a bin-shaped container, a bottle-shaped container, a dish-shaped container, a tray container, etc., in addition to the container provided with the flange. . Further, since the heat insulating container of the present invention has heat insulating properties and hardly causes dew condensation or the like on the surface, it is needless to say that the heat insulating container can be used as a container for cool food and drink.

The method of coating the outer surface of the inner layer with a foaming agent is performed by immersing the outer surface of the inner layer in a liquid containing a foaming agent and impregnating the outer surface of the inner layer with the liquid as described above. Preferably, the liquid may be coated by spray coating or the like.

[0051]

EXAMPLES 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 their weights were measured.
The strength, the heat insulating property, and the releasability of the inner layer and the heat insulating layer were evaluated as described below. Further, the weight, thickness, density and basis weight of each of the outer layer and the inner layer of the obtained heat insulating container and the thickness and density of the heat insulating layer were measured by the following measuring methods. Table 1 shows the results.

Example 1 An insulated container having the following dimensions and shape as shown in FIG. 1 was produced as follows.

<Container Dimensions> Height H: 110 mm Opening inner diameter φ1: 88 mm Bottom outer diameter φ2: 70 mm Body center thickness T2: 1.5 mm Bottom thickness T4: 1.0 mm Flange thickness T5: 0.8 mm

<Inner / Outer Layer Papermaking> A silicone rubber papermaking section corresponding to each of the inner and outer layers of the heat insulating container and a nylon net (50 mesh, wire diameter 100 μm) covering the papermaking section.
The male mold provided with m) was immersed in a slurry having the following composition to form each layer. 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 to 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 to pulp)

<Outer Layer Dehydration / Drying Conditions> 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)

<Coating of Outer Surface of Inner Layer with Foaming Agent> The inner layer (water content: 84%) is immersed in a foaming agent-containing liquid having the following composition.
The outer surface of the body of the inner layer was impregnated with a foaming agent. Blowing agent-containing liquid; Blowing agent (Matsumoto Yusei Pharmaceutical Co., Ltd. [Matsumoto Microsphere-F7
93]: water containing 1% by weight (5% by weight based on the total weight of the molded body) of a foaming temperature of 110 to 170 ° C.

<Heating and drying conditions> After the inner and outer layers were overlaid, they were dried under the following mold temperature and pressure to foam the foaming agent and to integrate the two layers. Mold temperature: 160 ° C Pressing load: 11760 N (60 seconds) Flange pressing force: 1.5 MPa Male mold temperature: 140 ° C

<Formation of Resin Layer> An inner layer of the following resin film was disposed so as to be in contact with an inner layer of the container, and was laminated under the following molding conditions. Outer layer / Inner layer = High-density polyethylene / Low-density polyethylene Resin layer thickness: 150 μm Molding conditions: Vacuum molding machine: PLAVAC-FE36PHS, manufactured by Sanwa Kogyo Co., Ltd. Film heating method: Infrared heater (interval between heater and resin film) 110mm) Film heating temperature: 250 ° C (display temperature of molding machine) Film heating time: 35 seconds Plug dimensions: diameter 60mm x length 110mm Plug material: aluminum (Teflon (registered trademark) processing on the surface) Plug temperature: 115 ° C (plug (Actual surface temperature) Vacuum forming mold: Hole diameter φ88mm, bottom diameter φ70m
m, height 110 mm Vacuum forming mold temperature: 115 ° C (actual surface temperature inside the mold) Molding time: 15 seconds

Example 2 The same procedure was followed as in Example 1 except that the weight of the pulp in the inner layer was made lighter than the weight of the pulp in the outer layer.

Comparative Example 1 A battery was manufactured in the same manner as in Example 1 except that no foaming agent was used for the heat insulating layer.

Comparative Example 2 Example 1 was repeated 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 consisting of only the foaming agent between the outer layer and the inner layer. It was produced in the same manner as described above.

[Measurement of Thickness of Outer Layer, Inner Layer and Heat Insulating Layer] Outer layer: A predetermined size (about φ
A 40 mm disk-shaped specimen was cut out, only the outer layer was separated from the specimen, and the thickness, weight and density of the outer layer were calculated by measuring the thickness and weight. Inner layer: Only the inner layer was separated from the specimen, and its thickness and weight were measured to calculate the thickness, basis weight and density of the inner layer. In the case where a mixed layer was formed between the inner layer and the heat insulating layer, the thickness, 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, the outer layer and the inner layer from the thickness and weight of the specimen. Resin layer: The thickness of the resin layer was measured by separating only the resin film from the test piece.

[Measurement of Compressive Strength] Lateral load (gripping strength): The obtained container was set horizontally on a compressive strength measuring machine (RTA-500, manufactured by Orientec Co., Ltd.), and the crosshead speed was set to 20 mm. / Min
And determined from the load when a displacement of 10 mm occurs in the body of the container. Longitudinal load: The obtained container was set vertically on the compressive strength measuring instrument, and the crosshead speed was set to 20 mm / min.
Was set and measured. When yielding due to buckling of the corner at the bottom of the container appears in the load-displacement curve, the load at the time of yielding (vertical load in Table 1) and the load at the time when the body buckles (maximum load: (1 longitudinal load) were measured.

[Heat insulation] 95 to 100 ° C.
Of hot water in the container, and after 3 minutes, the temperature of the hot water in the container and the temperature of the outer surface of the container were measured with a contact-type thermometer, and the temperature difference between the temperature of the hot water and the temperature of the outer surface of the container was determined.

[Releasability] 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 by a microscope.

[0066]

[Table 1]

As shown in Table 1, the containers in which the mixed layer was formed between the inner layer and the heat insulating layer (Examples 1 and 2) were thin, lightweight, and had desired mechanical strength and heat insulating properties. It was confirmed that delamination due to deformation did not occur. In contrast,
In the case of a container having no heat insulating material (Comparative Example 1) and a container having a heat insulating layer made of a heat insulating material but not having a mixed layer (Comparative Example 2), if the container is made thin and light, it is placed horizontally. When the deformation load (corresponding to gripping strength) is not sufficiently obtained (Comparative Example 1), and the mixed layer is not formed, delamination occurs and wrinkles and cracks may occur on the inner surface of the container. confirmed.

[0068]

According to the present invention, there is provided a heat insulating container which is thin, lightweight, and has both buckling strength and heat insulating properties.

[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 view showing a part of a manufacturing process of the heat insulating container of the present invention, wherein (a) shows a paper making process of an outer layer, and (b).
Is a diagram showing a dewatering / 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, and (e) is a diagram showing the inner layer. FIG. 3F is a view showing a superposition step of an outer layer, and FIG.

FIGS. 3A and 3B are schematic diagrams showing a resin layer forming step in the method for manufacturing a heat insulating container of the present invention, wherein FIG. 3A is a schematic sectional view showing a state where the container is set in a vacuum forming machine, and FIG. It is an expanded sectional view showing the adhesion state of the resin film in the flange part of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat insulation container 2 Inner layer 3 Outer layer 4 Heat insulation layer 5 Resin layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E061 AA26 AB11 AD07 DA02 3E067 AB01 BA03A BA07A BA10A BB15A BB16A BB17A BB24A BB30A CA04 CA18 EA04 EA32 FA01 FC01 GA11 GD05

Claims (7)

[Claims] 1. A heat insulating container comprising an inner layer and an outer layer formed mainly of pulp and an insulating layer formed of a heat insulating material between the inner layer and the outer layer,
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 through the mixed layer. A heat-insulating container, characterized in that: 2. The heat insulating container according to claim 1, wherein the mixed layer is formed on the inner layer side. 3. The heat insulating container according to claim 1, 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. 4. The heat insulating container according to claim 1, wherein said heat insulating material is a foaming heat insulating material. 5. The inner layer has a basis weight of 100 to 400 g / m.
^{2. The} outer layer has a basis weight of 250 to 500 g / m ² , the inner layer has a density of 0.4 to 0.8 g / cm ³ , and the outer layer has a density of 0.6 to 1.2 g / cm ^3. Claims 1-4 which are
The heat-insulating container according to any one of the above. 6. The heat insulating container according to claim 1, wherein an uneven portion or a step portion is formed on an inner surface of the inner layer. 7. The heat insulating container according to claim 1, further comprising a resin layer covering an inner surface of the inner layer.