JP2002120875A - Heat-insulating container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-insulating container which is thin-walled and excellent in shape-forming property, and has heat insulation and strength at predetermined parts. SOLUTION: This heat-insulating container comprises an inner pulp layer 2 and an outer pulp layer 3 mainly consisting of pulp, and further comprises a foaming agent layer 4 between the inner pulp layer 2 and the outer pulp layer 3. This heat-insulating container has parts of different total layer thickness and different total layer density.

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 and a method of manufacturing the same, and more particularly, to a heat insulating container which is thin and has excellent shape retention and has heat insulating properties and strength at a desired portion, and a method of manufacturing the same.

[0002]

2. Description of the Related Art As a prior art relating to a pulp molded article having a layer structure containing a foaming agent, the one described in, for example, JP-A-10-96200 is known. In this technique, a wet pulp molded article containing a foaming agent is placed in a dry mold having a predetermined clearance, and the clearance is filled by foaming of the foaming agent.

[0003] However, although this molded article has an improved surface smoothness, it is a buffer material obtained by molding from a pulp slurry containing a thermally expandable microcapsule-type foaming agent, so that it has a printing property. Have no aptitude,
In addition, the surface has low surface strength (scratch strength), easily generates paper dust and the like, and does not have such smoothness as to allow the resin film layer to adhere. For this reason, it is unsuitable for containers for food and drink, especially containers used by pouring hot water such as containers for instant cup noodles.

[0004] As another prior art relating to a paper heat insulating container, there is known a container of Japanese Utility Model Registration No. 3065471. The container according to this technique is provided with an exterior material having a rib fitted on the outside of the container main body, and imparts heat insulation to the container by a gap between the rib and the container main body.

[0005] However, in this container, heat insulation is imparted by the gap. However, since the bonding portion between the container body and the outer container is limited, the integrity of the container is not sufficiently obtained, and the shape retention is not improved. It was inferior. In particular, if hot water is poured and used, the container body itself made of paper is easily deformed by the heat and weight of the hot water, so the container body itself must be made thick and strong, and the weight increases accordingly. As a result, it was not suitable for this type of container.

On the other hand, in a heat insulating container, it has been desired to impart heat insulating properties and strength to necessary portions according to the shape of the container and the like.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a heat insulating container which is thin and excellent in shape retention and has heat insulating properties and strength at a predetermined portion, and a method of manufacturing the same.

[0008]

The present invention comprises an inner pulp layer and an outer pulp layer mainly made of pulp and a foaming agent layer between the inner pulp layer and the outer pulp layer. The object has been achieved by providing a heat-insulating container having portions having different total layer thicknesses and total layer densities.

The present invention also relates to a heat insulating container comprising an inner pulp layer and an outer pulp layer mainly made of pulp and a foaming agent layer between the inner pulp layer and the outer pulp layer. In the production method, the inner pulp layer and the outer pulp layer are separately formed, and after covering the outer surface of the inner pulp layer with a foaming agent, the foaming agent is applied to the inner pulp layer and the outer pulp layer. The object has been achieved by providing a method for manufacturing a heat insulating container in which the outer pulp layer and the inner pulp layer are stacked and dried so as to be located between the two, and the foaming agent is foamed.

[0010]

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 comprises an inner pulp layer 2 and an outer pulp layer 3 made mainly of pulp.
And the inner pulp layer 2 and the outer pulp layer 3
A foaming agent layer 4 is provided between them. The heat insulating container 1 has a total layer thickness (hereinafter, referred to as a thickness) in accordance with the expansion ratio of the foaming agent of the foaming agent layer 4. And the entire layer density is different in the body portion 10, and the total layer thickness and the total layer density are different in the vertical direction of the body portion.

In the heat insulating container 1, the whole layer thickness and the whole layer density of the body portion 10 are different from each other at the steps 10a and 10b. It is lower. The step 10a is an indicator of the hot water injection (line of sight), and the step 10b
Is a step (stacking step) when the empty heat-insulating containers are stacked. 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. Steps 10a, 10 due to changes in the total thickness of the body 10
b is formed in the inner pulp layer 3. By forming the steps 10a and 10b in the inner pulp layer 3 according to the change in the total thickness of the body 10 in this manner, the surface of the outer pulp layer 3 which becomes the outer surface 11 of the container 1 is formed flat. And good printability is obtained.

The density of the inner pulp layer 2 and the outer pulp layer 3 is as follows:
In terms of surface smoothness, surface strength, compressive strength, waterproofness, shape retention, prevention of paper powder generation during stacking, cushioning when filling contents or stacking heat insulating containers, 0.2
~ 1.5 g / cm ³ , preferably 0.4 ~
More preferably, it is 1.0 g / cm ³ . In the heat insulating container 1, the density of the outer pulp layer 3 is higher than the density of the inner pulp layer 2 in that the outer pulp layer 3 mainly has shape retention performance such as compressive strength, stack strength, and grip strength. Is preferred.

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.
Further, the thickness of the inner pulp layer is preferably 0.2 to 1 mm from the viewpoints of stability during papermaking, shape retention, thin and light weight, imparting compressive strength, shortening of papermaking or drying time, and the like.
0.4 to 1 mm, more preferably 0.5 to 1 mm.
mm is most preferred. In addition, at the same point as the inner pulp layer, the thickness of the outer pulp layer is 0.2 to 1 mm.
Is preferably 0.4 to 1 mm, and most preferably 0.5 to 1 mm.

In the heat insulating container 1, the surface smoothness of at least the portion of the inner pulp layer 2 which is to be the inner surface of the heat insulating container 1 is improved in terms of adhesion to a resin film described later, prevention of pinholes in the resin film, and the like. Center line average roughness Ra and maximum height Rmax measured by the method of the following example
And Ra is 1 to 20 μm (JIS B 0601).
Value measured according to. same as below. ), Rmax is 10
It is preferably 0 μm or less (a value measured according to JIS B0601; the same applies hereinafter), and Ra is 2 to 1.
More preferably, 0 μm and Rmax are 80 μm or less.

In the heat insulating container 1, the surface smoothness of at least the portion of the outer pulp layer 3 which is to be the outer surface of the heat insulating container 1 is determined by the method of the following example in order to improve printability. In the line average roughness Ra and the maximum height Rmax, Ra is preferably 1 to 8 μm, Rmax is preferably 60 μm or less, and Ra is preferably 2 to 6 μm and Rmax is 50 μm or less. On the other hand, the portion of the outer pulp layer 3 which is in contact with the foaming agent layer 4 is formed from the viewpoint of increasing the contact area between the outer pulp layer 3 and the foaming agent layer 4 and increasing the bonding strength between the two. It is preferable to roughen the paper and make the surface relatively rough.

The inner pulp layer 2 and the outer pulp layer 3 are made mainly of pulp and may be made of only pulp fiber. Alternatively, the pulp fiber may be made of an inorganic material such as talc or kaolinite, or a glass fiber. And other components such as inorganic fibers such as carbon fibers, thermoplastic synthetic resin powders or fibers such as polyolefins, non-wood or vegetable fibers, and polysaccharides. The amount of these other components is 1 to 7 based on the total amount of the pulp fiber and the other components.
It is preferably 0% by weight, particularly preferably 5 to 50% by weight.
Further, the inner pulp layer 2 and the outer pulp layer 3 may contain a fiber dispersant, a molding aid, a coloring pigment, a coloring aid, and the like, which are appropriately added during the papermaking.

The foaming agent layer 4 is preferably formed mainly of a foaming agent, and more preferably is composed of only a foaming agent. When the foaming agent layer is formed only of the foaming agent, the weight of the container can be reduced, and the step for the stack can be formed with high accuracy. Further, at the time of drying, the inner pulp layer in the wet state is intensively disposed on the male mold side, and the inner pulp layer in the wet state can be pressed by the foamed foaming agent to the male mold and dried. Efficiency can be increased. Furthermore, since the foaming agent layer plays the role of a steam ventilation path, drying unevenness of the inner pulp layer is small, and drying can be performed efficiently in a short time.

As the foaming agent used in the foaming agent layer, a foaming agent such as a microcapsule type foaming agent, a foaming resin, and an inorganic foaming agent such as sodium hydrogen carbonate is preferably used.
Among these, a microcapsule-type foaming agent is preferable in that the expansion ratio can be increased and the handleability is excellent, and in particular, those whose contents are butane, pentane, etc., and whose outer skin is vinylidene chloride, acrylonitrile, etc. are preferably used. Can be

In the foaming agent layer, pulp fibers, 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, Other components such as polysaccharides may be contained. In addition, when the foaming agent contains the above-mentioned other components, the foaming agent can be entangled with these components so that the heat insulating property can be obtained with a small amount of the foaming agent and the characteristics of each component can be imparted. In particular, when pulp fibers are contained, it is possible to obtain a low cost material having excellent compressive strength and grip strength. The amounts of these other components are appropriately set so that the density of the foaming agent layer is not increased, the heat insulation is not reduced, and the weight of the container is not increased.

The foaming agent layer is preferably formed without any gaps on the body and bottom of the container in terms of strength. For example, vacuum forming (skin pack) as described later is formed on the inner surface of the container.
From the viewpoint of air permeability (suction property of the resin film) when disposing the resin film by the above, it is preferable that the resin film is partially formed on the trunk and the bottom. The density and distribution of the foaming agent layer can be appropriately adjusted in consideration of container strength, heat insulating properties, and air permeability when disposing the resin film by vacuum forming.

In the heat insulating container 1, the foaming agent layer 4 is formed between the inner and outer pulp layers 2 and 3, and has a predetermined heat insulating performance. Specifically, the value of the temperature difference measured by the method of the following example is 20 to 40 ° C., and the surface temperature is 5
0 to 65 ° C., and the value of the temperature difference is 25 to
More preferably, the temperature is 35 ° C and the surface temperature is 55 to 60 ° C.

The heat-insulating container 1 has a flange 23 at the periphery of the opening 12 to which the inner pulp layer 2 and the outer pulp layer 3 are joined without interposing the foaming agent layer 4. Thus, by joining the inner pulp layer 2 and the outer pulp layer 3 without the intermediary of the foaming agent 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 provided with a resin film layer 5 covering the inner surface of the inner pulp layer 2 and the joining end of the flange portion 23. The resin film layer 5 is for imparting water resistance (leakage prevention), gas barrier properties and the like to the container. Therefore, the resin film used for the resin film layer 5 is:
There is no particular limitation on the material, thickness, etc. as long as it can provide the function, but, for example, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon, and polyolefin resins. Thermoplastic resins such as polyvinyl resins such as vinyl chloride and styrene resins such as polystyrene are used, and among these, polyolefin resins are particularly preferably used in view of film production cost and moldability. Further, the resin film layer 5 may have a single layer structure or a multilayer structure.

The heat insulating container 1 is covered with the resin film layer 5 up to the back surface of the flange portion 23. With this,
In addition to preventing water from entering from the joint end of the flange 23, which is the joint end of the outer pulp layers 2 and 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.

In the heat insulating container 1, the inner / outer pulp layers 2 and 3 and the foaming agent layer 4 have a mixed layer containing pulp and a foaming agent at the boundary between the inner pulp layer 2 and the foaming agent layer 4. The two layers are firmly integrated by the mixed layer, and are integrated by the fusion of the foaming agent at the boundary between the outer pulp layer 3 and the foaming agent layer 4. Inner pulp layer 2 and foaming agent layer 4
Is strongly integrated, so that high heat insulation and shape retention can be obtained even when hot water or the like is poured.

The heat insulating container 1 of the present embodiment is thin and excellent in heat insulation and has mechanical strength because the foaming agent layer 4 is formed and integrated between the inner and outer pulp layers 2 and 3. (Compressive strength).

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.

Further, 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, and the expansion ratio is suppressed near the flange 23 which does not require much heat insulation to increase the strength. It is an excellent container having a high foaming ratio from the center to the bottom of the body requiring heat insulation to increase heat insulation, and having heat insulation and strength at necessary places.

Further, at the boundary between the inner pulp layer 2 and the foaming agent layer 4, a mixed layer in which the pulp and the foaming agent are mixed is formed, and both are firmly integrated by the mixed layer. Since the boundary between the layer 3 and the foaming agent layer 4 is integrated by fusing the foaming agent, the inner pulp layer 2, the outer pulp layer 3, and the foaming agent layer 4 are firmly integrated, and hot water is poured. In this case as well, high heat insulation and shape retention can be obtained, and even if the container is deformed by gripping or the like, each layer is an excellent container that is difficult to peel off.

In addition, by controlling the expansion ratio of the foaming agent by changing the clearance of the male mold, it is possible to easily and freely change the functional shape such as the score line, the step for the stack, and the decorative shape such as characters and logos. A container that can be provided.

Next, a method of manufacturing the heat insulating container of the present invention will be described as a preferred embodiment based on the above-described method of manufacturing the heat insulating container 1 with reference to the drawings.

In the method of manufacturing the heat insulating container 1, first,
The inner pulp layer and the outer pulp layer are separately formed. Each pulp 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 paper-making part used in this paper-making is made of a heat-resistant and corrosion-resistant elastic material such as 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. In addition, a female mold having a heating means is used because it can perform drying as well as dehydration.

The inner pulp layer 2 and the outer pulp layer 3 are, for example, as shown in FIGS. 2A and 2C, a male mold 30 in a pool P3 filled with a slurry corresponding to each pulp layer.
After the male mold 20 is immersed in the pool P2, the slurry is sucked through the gas-liquid flow passage (not shown), and the pulp fiber is made into paper using the net (not shown). The paper is wet-formed on the outer surface of the net.

The slurry used for forming each pulp 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 and the like. A component may be contained. The amount of these components is 1 to 70% by weight, especially 5 to 50% by weight based on the total amount of the pulp fiber and the components.
% By weight. Further, 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 agent, when the outer pulp layer dried to a predetermined moisture content and the inner pulp layer in a wet state are integrated, the outer pulp layer absorbs moisture of the inner pulp layer. Can be prevented, and appearance defects such as spots on the outer surface of the outer pulp layer can be prevented.

The outer pulp layer 3 is dried and densified in advance before overlapping with the inner pulp layer, from the viewpoint that the foaming agent can be efficiently foamed to form the foaming agent layer 4. Specifically, after papermaking for a predetermined time, the male mold 30 is pulled out of the slurry, and butted against a metal female mold 31 corresponding to the male mold 30 as shown in FIG. The female mold 31 preferably does not have an exhaust hole on its inner surface so as not to leave behind on the outer surface of the outer pulp layer 3. However, if it is desired to shorten the drying time, it has an exhaust hole. Those can also be used.

Then, the outer pulp layer 3 in a wet state is pressed by the paper making section of the male mold 30 to perform dehydration, and the female mold 31 is further heated by its heating means (not shown) to dry the outer pulp layer 3. To increase the density. During dehydration and drying of the outer pulp layer 3, the water (water and steam) of the outer pulp layer 3 is sucked through the gas-liquid passage of the male mold 30 and drained to the outside.

The pressing force at the time of dehydration and drying of the outer pulp layer 3 is set at 0.
Preferably 2 to 3 MPa, 0.3 to 1.5 M
More preferably, it is Pa. The mold temperature (temperature of the female mold 31) when drying the outer pulp layer 3 is 150 to 23 in terms of prevention of scorching due to drying, drying efficiency, and the like.
The temperature is preferably 0 ° C, more preferably 170 to 220 ° C. After dehydration and drying of the outer pulp layer 3, the outer pulp 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 pulp layer 3, the outer surface of the inner pulp layer 2 is covered with a foaming agent.
As shown in FIG. 2 (d), for example, as shown in FIG. 2D, the male mold 20 in which the inner pulp layer 2 is formed in a pool P filled with a liquid containing a foaming agent (a dispersion or a solution of the foaming agent) is used. It can be carried out by immersion to impregnate the outer surface of the inner pulp layer 2 with the liquid.

The water content of the inner pulp layer 2 before coating with the foaming agent is preferably 90 to 60% from the viewpoint that the foaming agent and the pulp fiber are entangled to easily form a mixed layer. % Is more preferable.

By impregnating the outer surface of the wet inner pulp layer 2 with the liquid containing a foaming agent in this way, the foaming agent adheres to the pulp fibers on the outer surface of the inner pulp layer in a tangled manner. Then, when the foaming agent is foamed thereafter, a mixed layer in which both are mixed is formed, and the inner pulp layer 2 and the foaming agent layer 4 are firmly integrated by the mixed layer. When adhering the foaming agent to the outer surface of the inner pulp layer 2, negative pressure suction can be performed through the gas-liquid flow passage of the male mold 20 as necessary, and thereby the entanglement between the pulp fiber and the foaming agent can be reduced. It can also be adjusted.

The foaming agent has a foaming temperature of 10 from the viewpoint of suppressing scorching of the pulp fibers of the pulp layer due to heat foaming.
Those having a temperature of 0 to 190 ° C are preferable, and those having a temperature of 110 to 160 ° C are more preferable. Examples of the foaming agent having such a foaming temperature and dispersibility in water or slurry include a microcapsule-type foaming agent, a foamable resin, and the like. Microcapsule-type foaming agents are preferably used. In the microcapsule type foaming agent, for example, the contents are butane, pentane, etc.
Microcapsule-type foaming agents such as vinylidene chloride and acrylonitrile having an outer skin are preferably used.

The amount of the foaming agent is preferably 1 to 20% by weight with respect to the total weight of the heat insulating container in view of the above-mentioned predetermined density and thickness of the foaming agent layer and the production cost. More preferably, it is 3 to 10% by weight.

Next, the inner pulp layer 2 and the outer pulp layer 3 are overlapped so that the foaming agent layer is located between the inner pulp layer 2 and the outer pulp layer 3. That is, as shown in FIG. 2E, the inner pulp layer 2 impregnated with the foaming agent is overlaid from above the dewatered and dried outer pulp layer 3 arranged in the female mold 31. At this time, the inner pulp 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 pulp layer 2 and the outer pulp layer 3 are brought into close contact with each other while pressing the wet inner pulp layer 2 in 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 to transfer the inner pulp layer 2 from the male mold 20 to the female mold 31. After handing over the inner pulp layer 3, the male mold 2
0 is saved.

Next, as shown in FIG. 2 (f), a metal mold 2 having a predetermined clearance C corresponding to a 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. By using a mold having such a clearance C,
Even when molding deep-shaped containers with a small taper,
The container can be inserted while suppressing the contact with the inner pulp layer, and the inner surface of the container obtained after drying can be smoothed. The male mold 21 has a gas-liquid flow path (not shown), like the male mold 20, and has a heating means (not shown). Then, the male mold 21 and the female mold 31 are heated by respective heating means to foam the foaming agent impregnated in the inner pulp layer 2 to lower the density of the foaming agent layer 4, and to reduce the inner pulp layer 2 and the outer pulp. The layer 3 is integrated.

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.

At the time of drying, the moisture in the inner pulp layer 2 is discharged as steam through the gas-liquid flow passage of the male mold 21 to the outside.

Mold temperature during drying (male 21 and female 31)
Is preferably 110 to 230 ° C., from the viewpoint of keeping the drying efficiency high, while keeping the foaming start temperature or higher and preventing the pulp layers 2 and 3 from being scorched. C. is more preferable.

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

Next, the resin film layer 5 is formed so as to cover the inner surface of the inner pulp layer 2 and the joint end of the flange portion 23.
To form The resin film 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. 3 (a), the vacuum suction path 60 having substantially the same size as the female 31 (see FIG. 2) used in the dewatering / drying step of the outer pulp layer 3 is provided. Using a vacuum forming die 6 equipped with a band heater 61, a semi-insulated container of semi-finished product is set in the die 6, 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 pulp layer 3.

As shown in FIG. 3 (b), a predetermined clearance is provided between a portion 62 of the vacuum forming die 6 which faces the lower surface of the flange 23 and the flange 23, and a vacuum suction path is also provided in the portion 62. By providing 60 suction ports, the resin film layer 5 can be brought into close contact with the lower surface of the flange 23, whereby the flange 2
3 can be reliably covered with the resin film 50.

As described above, according to the method for manufacturing the heat insulating container 1 of the present embodiment, a thin heat insulating container excellent in shape retention and heat insulating performance can be suitably manufactured.

The present invention is not limited to the above embodiment, but can be modified without departing from the spirit of the present invention. For example, in the case of a cup-shaped container as in the heat-insulating container 1 of the above-described embodiment, portions having different total layer thicknesses and different densities are formed on the body (grip portion) according to the expansion ratio of the foaming agent. Although it is preferable, the portion where the total layer thickness and the total density are different according to the expansion ratio of the foaming agent can be appropriately set according to the shape of the container. For example, when the shape of the container is a dish-shaped container Can be formed in other parts such as a trunk and a bottom. In addition, it is preferable to form a step for the stack on the body, but the step for the stack can be omitted as necessary.

Needless to say, the heat insulating container of the present invention can be applied to containers having various shapes such as a bin-shaped container, a bottle-shaped container, a dish-shaped container, and a tray container, in addition to the container having 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.

Further, in the heat-insulating container of the present invention, as in the heat-insulating container 1 of the above embodiment, it is preferable that the flange portion is formed flat, but after forming the flat flange portion, as shown in FIG. Also, the flange portion 23 may be rounded. By making the flange portion 23 round as described above, in a case where the lid material 8 is adhered to the heat insulating container 1 and sealed, the margin of the lid material 8 can be easily removed, and the flange 23 can be joined. Since the resin film layer 5 and the lid member 6 are separated from each other at the end, the peeling of the resin film layer 5 can be prevented when the lid member 8 is peeled off and opened.

In the method for manufacturing the heat insulating container of the present invention, as described in the above-described manufacturing method, it is preferable that the outer pulp layer 3 is previously dried and densified, and then superposed and integrated with the inner pulp layer 2. However, it is also possible to overlap the inner pulp layer without drying the outer pulp layer 3 in advance, and then dry both.

In the method of coating the outer surface of the inner pulp layer with a foaming agent, as described above, the outer surface of the inner pulp layer is immersed in a liquid containing a foaming agent, and the liquid is exposed to the outer surface of the inner pulp layer. It is preferably carried out by impregnation, but the solution can also be coated by spray coating or the like.

[0059]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. An insulated container having the following dimensions and shape in the form 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 upper part thickness T1: 0.8 mm Body part center part thickness T2: 1.5 mm Body part lower part thickness T3: 2.0mm Bottom thickness T4: 1.0mm Flange thickness T5: 1.0mm

<Paper Making of Inner Pulp Layer / Outer Pulp Layer> A paper making section made of silicone rubber corresponding to each inner and outer pulp layer of the heat insulating container and a nylon net (50) covering the paper making section.
A male mold having a mesh and a wire diameter of 100 μm) was immersed in a slurry having the following composition to form each pulp layer. Slurry for outer pulp 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 weight) For inner pulp layer Slurry; 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)

<Dehydration / Drying Conditions of Outer Pulp Layer> The outer pulp layer is disposed between the outer mold and the female mold corresponding to the male mold.
Dehydration and drying were performed under pressure under the following conditions. Mold temperature: 160 ° C Pressing force: 0.4 MPa (180 seconds)

<Coating of Outer Surface of Inner Pulp Layer with Blowing Agent> The inner pulp layer was immersed in a foaming agent-containing liquid having the following composition, and the outer surface of the body of the inner pulp layer was impregnated with the blowing agent. Blowing agent-containing liquid; Blowing agent (Matsumoto Yusei Pharmaceutical Co., Ltd. [Matsumoto Microsphere-F8
2]: Water containing 1% by weight (5% by weight based on the total weight of the molded body) of a foaming temperature of 160 to 170 ° C.

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

<Formation of Resin Film Layer> The following resin films were arranged so that the inner layer was in contact with the inner pulp layer, and were laminated under the following molding conditions. Outer layer / Inner layer = High-density polyethylene / Low-density polyethylene Resin film layer thickness: 150 μm Molding conditions; Vacuum molding machine: PLAVAC-FE36PHS, manufactured by Sanwa Kogyo Co., Ltd. Film heating method: Infrared heater (for heater and resin film) (Interval 110 mm) Film heating temperature: 250 ° C. (display temperature of molding machine) Film heating time: 35 seconds Plug dimensions: diameter 60 mm × length 110 mm Plug material: aluminum (Teflon (registered trademark) processed 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

[Measurement of Thickness and Total Thickness of Each Layer] A piece was cut out from the molded body, and the thickness of each layer was measured with a tool microscope.

[Measurement of Density of Each Layer] The thickness, the area of the cut pieces and the weight thereof, the total weight of the molded body,
Based on the weight of the blowing agent, the density of the blowing agent layer and the inner pulp layer was calculated.

[Evaluation of Insulation Characteristics]
Pour hot water at 00 ° C., measure the temperature of the hot water in the container and the temperature of the outer surface of the container after 3 minutes with a contact thermometer, and determine the temperature difference between the temperature of the hot water and the temperature of the outer surface of the container. .

[Measurement of Smoothness of Inner Surface] The surface roughness was measured using Surfcom 120A (manufactured by Tokyo Seimitsu Co., Ltd.).
The measurement conditions were as follows: cutoff: 2.5 mm, measurement length: 1
0.00mm, filter: 2CR, measurement magnification: 500,
Tilt correction: straight line, polarity: standard.

The heat-insulating container manufactured in this way has a total thickness of 0.8 to 5 mm, is thin and lightweight,
In addition, the heat insulation was good, and the container could be directly gripped even by pouring hot water, and the shape retention was also maintained at that time. In addition, the surface has high smoothness and the center line average roughness Ra is 1 to 2
0 μm, the maximum height Rmax was 100 μm or less, the adhesion of the resin film was good, there was no pinhole, and the printability of the outer surface was also good.

[0071]

The heat-insulating container of the present invention is thin and excellent in shape retention, and has heat insulation and strength at a predetermined portion. Further, the method for manufacturing a heat insulating container of the present invention can suitably manufacture a heat insulating container exhibiting the above-described effects.

[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 production process of the heat insulating container of the present invention, wherein (a) is a diagram showing a papermaking process of an outer pulp layer,
(B) is a diagram showing a dewatering / drying step of the outer pulp layer, (c)
Is a diagram showing a paper making process of the inner pulp layer, (d) is a diagram showing a process of coating the outer surface of the inner pulp layer with a foaming agent, and (e).
Is a diagram showing a superposition process of the inner pulp layer and the outer pulp layer,
(F) is a figure which shows a drying process.

FIG. 3 is a schematic view showing a step of forming a resin film layer in the method for producing a heat insulating container of the present invention, and (a) is a schematic sectional view showing a state where the container is set in a vacuum forming machine;
(B) is an enlarged sectional view showing the state of adhesion of the resin film at the flange portion of (a).

FIG. 4 is a schematic cross-sectional view of a main part showing another embodiment of a flange portion in the heat insulating container of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated container 2 Inner pulp layer 3 Outer pulp layer 4 Foaming agent layer 5 Resin film layer 10 Body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Sato 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Pref. (72) Inventor Osamu Nakata 2606 Kabane-cho, Akabane-cho, Haga-gun, Tochigi Pref. 72) Inventor Shinji Kodama 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Pref. In Kao Co., Ltd. (72) Inventor Shingo 2606 Kabachi-cho, Akabane, Haga-gun, Tochigi Pref. In Kao Co., Ltd. BB08 CA03 CA08 DA08 DD01 FA04 3E067 AA03 AB26 AC01 BA02A BA07A BB01A CA18 EA06 EB27 FA01 FC01 GA11

Claims (9)

[Claims] 1. A heat insulating container comprising an inner pulp layer and an outer pulp layer mainly made of pulp and a foaming agent layer between the inner pulp layer and the outer pulp layer. An insulated container having portions having different layer thicknesses and total layer densities. 2. The heat insulating container according to claim 1, wherein the body has the portion, and the total layer thickness and the total layer density are different in a vertical direction of the body. 3. The heat insulating container according to claim 1, wherein the density of the outer pulp layer is higher than the density of the inner pulp layer. 4. The heat insulating container according to claim 1, wherein a step due to a change in the total layer thickness is formed in the inner pulp layer. 5. The heat insulating container according to claim 1, further comprising a flange portion joined to the inner pulp layer and the outer pulp layer without interposing the foaming agent layer at a periphery of the opening. 6. The heat insulating container according to claim 1, further comprising a resin film layer covering an inner surface of the inner pulp layer and a joint end of the flange portion. 7. A method for producing an insulated container comprising an inner pulp layer and an outer pulp layer mainly made of pulp and a foaming agent layer between the inner pulp layer and the outer pulp layer. Then, the inner pulp layer and the outer pulp layer are separately formed, and after covering the outer surface of the inner pulp layer with a foaming agent, the foaming agent is located between the inner pulp layer and the outer pulp layer. The outer pulp layer and the inner pulp layer are overlapped and dried to foam the foaming agent. 8. The method according to claim 7, wherein the outer pulp layer is dried and densified in advance before the outer pulp layer is overlaid on the outside of the foaming agent layer. 9. When foaming the foaming agent, a mold having a predetermined clearance between the inner pulp layer and the inner surface of the inner pulp layer is provided, and the clearance is filled. The method according to claim 7, wherein the foaming agent is foamed.