JPH11193019A - Paper container that can be retort pasteurized - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a paper container which can be used in a microwave oven and can be retort pasteurized. SOLUTION: A container body is comprised of a cylindrical body 120 and a bottom body 130, wherein the bottom body 130 whose outer periphey extends downward is thermally bonded to the lower end of the cylindrical body 120 in such a manner that the outer periphery of the extended part of the outer periphery of the bottom body 130 is at the same level with the lower end of the body 120. And inner and outer edges of the cylindrical body which are bonded together is covered with a laminated film 20. An opening circumferential edge member 31 is thermally bonded to the outer periphery of the upper portion of the container body, and a bottom edge annular member 33, which holds the lower end of the cylindrical body 120 and the cicumferential edge of the bottom of the container body thermally bonded to the outer periphery of the extended part of the bottom body from the inside and the outside, is thermally bonded to the lower end of the body 120 and the lower end of the bottom body 130. And the members 31, 33 are provided by injection molding molten polypropylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container capable of retort sterilization, and more particularly to a cup-shaped paper container capable of being reheated by a microwave oven.

[0002]

2. Description of the Related Art Paper containers which can be subjected to a retort sterilization treatment are disclosed, for example, in JP-A-57-46734 and JP-A-5-46734.
Many inventions and ideas have been disclosed, including the inventions disclosed in JP-A-8-52033 and JP-A-58-20638.

[0003] The invention disclosed in Japanese Patent Application Laid-Open No. 57-46734 discloses a synthetic resin or paper mainly composed of a thermoplastic resin excluding a high-density polyethylene resin and having a melting point of 115 ° C or higher as both outer layers. The both ends of the laminated sheet made of aluminum foil are rolled and subjected to waterproofing and welded to form a cylindrical body, and the upper and lower openings of the obtained cylindrical body are formed with the synthetic resin in the laminated sheet. A container closed with a lid made of aluminum foil whose inner surface is coated with the same kind of synthetic resin, wherein the laminated sheet is a packaging container having a laminated structure in which aluminum foil is disposed on both sides of paper. Things.

Further, the invention disclosed in Japanese Patent Application Laid-Open No. 58-52033 discloses a method in which both ends corresponding to a body seal portion of a fan-shaped or rectangular blank sheet made of a paper material subjected to a water-resistant treatment on both sides are opposite to each other over a certain width. The upper and lower parts of the body cylinder formed by folding both sides of the blank sheet so as to form a cylinder and bonding both ends at the surface having the pair of folded pieces obtained above, This is a completely water-resistant paper container which is sealed with a cylindrical body and a bottom plate so that the paper end surface is not exposed.

Further, in the invention disclosed in Japanese Patent Application Laid-Open No. 58-20638, the resin layer forming the inner layer and the intermediate layer made of paperboard and the like are integrally bonded, and the resin layer forming the outer layer and the intermediate layer are integrally bonded. Alternatively, the resin is bonded to each other at the upper edge of the container, the layers are degassed, and a multilayer container is formed in which an intermediate layer is sandwiched between resin layers on both sides.

[0006] However, these inventions have a problem that they are not suitable for microwave ovens because they use a lot of aluminum foil, and there remains a problem in the disposal property because they use a lot of synthetic resins.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems relating to a paper container capable of performing a retort sterilization treatment, and provides a paper container capable of performing a retort sterilization treatment suitable for a microwave oven. The purpose is to do.

[0008]

Means for Solving the Problems A first invention of the present invention is:
At the lower end of a cylindrical body having a bonded portion composed of a laminated sheet mainly composed of a paper layer, a circular bottom body composed of the laminated sheet having an outer peripheral edge rising downward, an inner peripheral edge of the cylindrical body, A container body formed by thermally bonding an inner peripheral edge of an outer peripheral edge of the bottom body standing downward to the lower end edge of the cylindrical body and a lower peripheral edge of the outer peripheral edge of the bottom body so as to be flush with each other, And a tape-shaped laminated film for covering both the inner and outer edges formed at the bonded portion of the cylindrical body. An opening peripheral member to be attached, and a bottom edge ring that is positioned so as to be sandwiched from below along the periphery of the bottom of the container body formed by thermal bonding between the lower end of the cylindrical body and the rising outer peripheral edge of the bottom body and that is thermally fused The member is sprayed with hot melt polypropylene resin. A retort sterilization processable paper container provided by molding.

In a second aspect based on the first aspect, the laminated sheet is laminated from the outside of the container in the order of an unstretched polypropylene (CPP) film, a cup base paper, a barrier layer, and an unstretched polypropylene (CPP) film. This is a paper container capable of being subjected to a retort sterilization treatment, which is a laminated sheet having at least four layers.

According to a third aspect of the present invention, in the first and second aspects, the CPP film located on the outside of the container is a block type or random type CPP film. The CPP film located on the side that comes into contact with the object is a paper container that can be subjected to retort sterilization, which is a block-type CPP film.

According to a fourth aspect, in the first, second and third aspects, the barrier layer constituting the laminated sheet is a film on which an inorganic compound vapor-deposited thin film is formed, or a film on which a metal compound vapor-deposited thin film is formed. Or a retort sterilizable paper container that is either a plastic film or a barrier plastic film.

According to a fifth aspect of the present invention, in the first, second, third and fourth aspects, the cup base paper constituting the laminated sheet has a diatomaceous earth coating layer of 12 on the base paper surface.
It is a paper container that can be subjected to a retort sterilization treatment, which is a cup base paper coated with １８18 g / m ² .

[0013] In a sixth aspect of the present invention, the first, second, third,
In the fourth and fifth inventions, there is provided a paper container which can be subjected to a retort sterilization treatment, wherein the tape-shaped laminated film is a laminated film having at least a three-layer structure in which a polypropylene film, a barrier layer, and a polypropylene film are laminated in this order.

Further, a seventh aspect of the present invention relates to the first, second, third,
In the fourth, fifth and sixth inventions, the barrier layer constituting the tape-shaped laminated film is any one of a film formed with an inorganic compound vapor-deposited thin film, a film formed with a metal compound vapor-deposited thin film, or a barrier plastic film. This is a paper container that can be subjected to a retort sterilization treatment.

An eighth invention is directed to the first, second, third,
In the fourth, fifth, sixth and seventh inventions, the polypropylene resin used for the injection molding method, wherein the polypropylene resin used for the peripheral member of the opening has an MFR of 8 to 3.
This is a paper container that can be subjected to a retort sterilization treatment, which is a block type 0 polypropylene resin.

[0016]

As described above, according to the present invention, the laminated sheet end face exposed to the outside after the paper container is formed is covered with the tape-shaped laminated film, and the outer peripheral edge of the opening and the peripheral edge of the front end of the joint portion between the cylindrical body and the bottom body are formed. Retort sterilization is possible because it is coated with polypropylene resin.

The laminated sheet may be a CPP film, a cup base paper, a film formed with an inorganic compound vapor-deposited thin film, a film formed with a metal compound vapor-deposited thin film, or a barrier plastic film, or a CPP film. A barrier layer composed of any one of a polypropylene film, a film formed with an inorganic compound vapor-deposited thin film, a film formed with a metal compound vapor-deposited thin film, or a barrier plastic film, and a polypropylene film Are suitable for a microwave oven.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. As shown in FIGS. 1 and 4, the paper container capable of performing the retort sterilization treatment of the present invention has a bonding portion (14).
(0), covering the container body (100) having the cylindrical body (120) and the bottom body (130), and the edges (150, 160) generated at the bonded portion (140) of the cylindrical body (120). It is composed of a tape-shaped laminated film (20), an opening peripheral member (31) covering the main part of the container body, and a bottom edge annular member (33).

As shown in FIG. 2, the laminated sheet (1) constituting the cylindrical body and the bottom body of the container main body is made of CP from the outside of the container.
P-film (2), cup base paper (3), barrier layer (4), and CPP film (5) are each laminated in this order, and a laminated sheet (1) having at least a four-layer structure.
It is.

The cup base paper (3) is a substrate of the laminated sheet, the basis weight 280g / m ² ~320g / m ² about what can be preferably used. In addition, use a cup base paper coated with a diatomaceous earth coat layer (3a) on the surface, because it has excellent pattern reproducibility when printing on paper and is a measure to prevent the appearance of yellowing due to the heat of the paper. Is preferred. The coating amount of the coat layer is preferably from 12 to 18 g / m ² .

The barrier layer (4) provided inside the cup base paper is made of a plastic film such as a polyethylene terephthalate (PET) film, a biaxially stretched nylon (ONy) film, a biaxially stretched polypropylene (OPP) film, or the like. 400 thin films of aluminum etc.
A deposited film deposited by a method such as a vacuum deposition method can be preferably used, but an ethylene vinyl alcohol copolymer resin (EVOH) film may be used.

The CPP film (2) used on the outside of the cup base paper has heat resistance of 120 ° C. or more, and
A block-type or random-type CPP film that does not require a significant change in molding conditions in a conventional cylinder molding machine when molding a cylinder or a bottom body can be preferably used, and a thickness of 30 to 70 μm is suitably used. it can.

The innermost layer of the laminated sheet (1), the CPP film (5) provided on the side in contact with the contents, has a low extraction amount of low molecular weight substances. Therefore, the contents are retort sterilized or hot-filled. However, it is necessary to use a block-type CPP film because it has a very small effect on taste and has excellent impact resistance during distribution.

In order to further reduce the generation of pinholes during the molding of the bottom body, a layer of a PET film (not shown) may be provided between the CPP film (2) and the cup base paper (3). The thickness of the PET film is preferably about 9 to 16 μm.

When a printed portion is provided on the laminated sheet (1), it is generally provided on the coat layer (3a) of the cup base paper (3). It may be provided on either of the front and back surfaces of the PET film, or may be provided on the coat layer.

The lamination of the cup base paper (3) and each of the above layers is as follows.
The laminated sheet (1) can be produced by laminating in an appropriate order by a commonly used known laminating method, for example, a dry lamination method using a two-component polyester adhesive. .

[0027] Separately, when one end face and the other end face of the body member blank, which is a cylindrical body of the container body, are bonded to each other, both of the end faces that come out and the one that goes inside are covered. CPP film (21) as shown in FIG. 3,
A tape-like laminated film (20) is prepared by sequentially laminating a barrier layer (22) and a CPP film (23).

The barrier layer (22) is made of a PET film,
ONy film, OPP film and other plastic films are coated with thin films of silicon oxide, aluminum oxide, etc.
A deposited film deposited by a method such as vacuum deposition can be preferably used, but an EVOH film may be used.

C provided on both sides of the barrier layer (22)
The PP films (21, 23) may be any of a homo type, a random type and a block type.

The CPP film (21) and the barrier layer (2)
2) and barrier layer (22) and CPP film (2
The bonding in 3) can be performed by a commonly used known laminating method, for example, a dry lamination method using a two-component type polyester adhesive, and the tape-shaped laminated film (20) can be easily formed. ) Can be prepared.

The tape-shaped laminated film (20) is heat-sealed to both ends of the body member blank to be the cylindrical body (120) of the container body by any of a heat sealing method, an impulse sealing method, and an ultrasonic sealing method. Depending on the method.
Further, the fusion process is preferably performed in a blank state before forming into a cylindrical shape.

The molding of the paper container can be performed, for example, as follows. First, in order to form the container body (100) from the laminated sheet (1), a body member blank serving as the cylindrical body (120) of the container body and a bottom member roll serving as the bottom body (130) of the container body are produced. . When assembling the cylindrical body of the body member blank, both inner and outer edge portions (150, 16) generated at the bonding portion (140) are formed.
0) is a heat-sealing method using the tape-shaped laminated film (20) described above, for example, in a state as shown in FIG.
The coating is performed using a heat sealing method such as an impulse sealing method or an ultrasonic sealing method.

A body member blank and a bottom member roll, each of which is covered with a tape-like laminated film at a required position, are set in a cylinder forming machine. First, the body member blank is bent into a cylindrical shape so that the CPP film (5) becomes the inner surface, and one end surface of the body member blank covered with the tape-like laminated film and the other end covered with the tape-like laminated film. To form a cylindrical body (120) having a bonded part (140).

Next, the inner surface of the circular bottom body (130) stamped from the bottom member roll and having its outer peripheral edge rising downward is heated by hot air or the like on the lower inner surface of the cylindrical body (120). FIG. 4 shows that the lower end edge of the cylindrical body and the lower end edge of the outer peripheral edge of the bottom body are heat-bonded under pressure so that
A paper container (50) as shown in FIG. At this time, it is important that the inner surface of the cylindrical body and the inner surface of the outer body are completely fused, and that the resin by melting of the inner CPP film be sufficiently buried in the bonding surface between the cylindrical body and the bottom body. ,
As a result, when the contents are filled, moisture and oil contained in the contents do not penetrate into the end surfaces of the cylindrical body and the bottom body.

A molten polypropylene resin is injected to cover the outer periphery of the opening of the paper container (50) thus produced and the periphery of the joint between the cylindrical body and the bottom body so that the end surface of the laminated sheet is not exposed. To

The resin used for coating the outer peripheral edge of the opening is:
A block type polypropylene resin having excellent impact resistance and less eluted low molecular weight components is used, and has an MFR of 8 to 30 g / 10 min. Is preferably used. The polypropylene resin used for coating the peripheral edge of the joint between the cylindrical body and the bottom body may be any of a homo-type, a random-type, and a block-type. In this way, a paper container that can be subjected to the retort sterilization process is manufactured.

[0037]

EXAMPLES Examples of the present invention will be described below more specifically. <Example 1> A laminated sheet (1) constituting a cylindrical body and a bottom body, a tape-shaped laminated film (20) for covering an end face exposed portion of a bonded portion of a cylindrical body obtained by molding the laminated sheet, and A lid member for sealing the opening of the container body was produced by a dry lamination method using a polyester resin-based two-component reactive adhesive with the following configuration.

Layer structure of laminated sheet (1), [outside of container]
CPP film (50 μm thickness) (2) / PET film (9 μm thickness) (6) / coat layer (coating amount: 15 g /
m ² ) (3a) / cup base paper (basis weight; 295 g / m ² )
(3) / PET film (12 μm thick), aluminum oxide deposited thin film (400 °) (4) / CPP film (5
0m thickness) (5) [Inside of container]

Layer structure of the tape-shaped laminated film (20),
CPP film (30 μm thickness) (21) / PET film (12 μm thickness), aluminum oxide deposited thin film (400
Å) (22) / CPP film (30 μm thick) (23)

Layer structure of lid member, [outside of container] PET film (12 μm thick), aluminum oxide evaporated thin film (40
0mm) / ONy film (14m thickness) / CPP film (70μm thickness) [inside of container]

The CPP film used for the laminated sheet (1) is a CPP film having the following constitution and physical properties. That is, propylene-ethylene block copolymer, melting point: 160 ° C., density: 0.90 g / cm ² , MF
R: 8 g / 10 min. ··· Ethylene content: 2.5w
t%, ethylene-butene copolymer (amorphous resin) is added to impart impact resistance.

The moisture content of the cup base paper is 5.0%.

In order to form a paper container (50) from the laminated sheet, a body member blank serving as the cylindrical body (120) of the container body and a bottom member roll serving as the bottom body (130) of the container body were prepared. Then, over all the exposed portions on both end surfaces which become the bonding portion (140) at the time of forming the body member blank,
As shown in FIG. 4 (b), a tape-shaped laminated film (20) having a width of 10 mm was impulse-sealed to cover the exposed portion of the paper end surface.

A cylindrical container was formed by using a body member blank in which the exposed portion of the paper end face was covered with a tape-shaped laminated film and a bottom member roll. The heating method employs a method of locally heating and pressing the CPP film outside the welded portion in order to prevent the generation of blisters due to vaporization of moisture in the cup base paper of the laminated sheet (detailed molding method is paragraph number 003).
3, 0034).

The opening outer peripheral member (31) is coated by injecting a hot-melted polypropylene resin onto the upper outer peripheral edge of the paper container (50) thus produced.
The bottom edge annular member (33) is injected by injecting a hot melt polypropylene resin so as to be sandwiched from below into the bottom edge of the bottom edge portion (00).
To prepare a paper container capable of being subjected to a retort sterilization treatment without any exposure of the paper end surface.

The polypropylene resin used for injection molding was
The following composition and physical properties were used. An ethylene-propylene copolymer; a melting point: 160
° C, density: 0.90 g / cm ³ , MFR: 8 g /
10 min.

<Comparative Example 1> A paper container made by the same material and molding method as in Example 1 except that the end surface of the body member constituting the cylindrical body (120) is not covered with the tape-like laminated film (20) (details) Detailed description is omitted).

Comparative Example 2 A paper container made of the same material and the same molding method as in Example 1 except that an aluminum foil having a thickness of 9 μm was used as a barrier layer constituting a laminated sheet (detailed description is omitted).

Reference Example 1 A plastic container having the same shape as in Example 1 (layer structure is polypropylene resin (PP) / EV)
OH / PP was made.

The suitability of the retort and the suitability of the microwave oven for three types of paper containers and one type of plastic container having the same shape as described above were tested and evaluated according to the methods described below.

<Experiment 1> Suitability of retort (1) After filling the above four types of containers with water and sealing with a lid member, a retort sterilization of a pneumatic method using an apparatus manufactured by Hisaka Seisakusho under the following two conditions. The processing was performed, and the state of the shape change of the container was observed. Table 1 shows the results. Condition 1 ‥‥ Initial temperature; 80 ° C., temperature rising condition; 120 ° C. reached 15 minutes Holding condition: 30 minutes, cooling time; 30 minutes Condition 2 ‥‥ Initial temperature; 80 ° C., temperature rising condition; 130 ° C. Achieved 15 minutes Holding condition: 30 minutes, cooling time: 30 minutes In Table 1, ○ indicates that the container has no shape change such as deformation, and × indicates that the bonded portion of the trunk is peeled off by water from the paper end surface. Indicates that the container has been torn.

<Experiment 2> Suitability of retort (2) The three types of containers of Example 1, Comparative Example 2 and Reference Example 1 were filled with the following oxygen barrier detecting material as contents and sealed with a lid member. Retort sterilization was performed under two conditions, and the presence or absence of oxygen barrier properties was observed. Table 1 shows the results. Oxygen barrier detection material も の A mixture of sucrose fatty acid ester, agar powder, sodium hydroxide, methylene blue, and D-glucose dissolved in hot water. Evaluation method of barrier properties こ と Methylene blue develops a blue color when exposed to oxygen. In Table 1, 透過 indicates that the content liquid does not develop a blue color and has an oxygen barrier property, and X indicates that the content liquid entirely develops a blue color.
Indicates that the oxygen barrier property has deteriorated, and-indicates that the experiment has not been performed.

[0053]

[Table 1]

<Experiment 3> Suitability for Microwave Oven (1) The three types of containers of Example 1, Comparative Example 2 and Reference Example 1 were heated by a microwave oven after the retort sterilization treatment under the following conditions. Observed and evaluated. Table 2 shows the results. The microwave oven has a rated voltage of 10
A commonly used one having 0 V and a rated frequency of 60 Hz was used. In Table 2, ○ indicates a state in which reheating by a microwave oven was successfully performed, and X indicates a state in which reheating by a microwave oven could not be performed.

[0055]

[Table 2]

From Tables 1 and 2, it can be seen that the paper container of the present invention in which the paper end surface is completely covered has not only the suitability for retort sterilization but also the suitability for a microwave oven after retort sterilization (Example 1). . Paper containers that did not cover the paper edge
It can be seen that when the retort sterilization treatment is performed, water penetrates from the end face of the paper to cause deformation of the container and cannot be used (Comparative Example 1). Further, it can be seen that the paper container using the aluminum foil for the barrier layer of the laminated sheet has retort sterilization suitability but not microwave oven suitability (Comparative Example 2). Furthermore, the plastic container having the PP / EVOH / PP configuration does not change its shape due to the retort sterilization treatment, and has a microwave oven suitability, but has a difficulty in gas barrier properties after the retort sterilization treatment (Reference Example 1). .

[0057]

As described above, since the paper container of the present invention is a container mainly composed of paper, it has excellent display properties and printability, and does not require a secondary container such as a plastic container.
Generation of garbage can be suppressed. Since it is a paper container, it has excellent incineration. Further, since retort sterilization treatment is possible, it can be used as a water-resistant container instead of a plastic bottle around water.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a retort sterilizable paper container of the present invention as viewed from the inside in a longitudinal section.

FIG. 2 is a sectional view showing one embodiment of a laminated sheet used for the paper container of the present invention.

FIG. 3 is a sectional view showing one embodiment of a tape-shaped laminated film used for the paper container of the present invention.

FIG. 4 is an explanatory view of a container body used in the present invention;
(A) is a front explanatory view in which a part of the container body is cut out,
(B) is an enlarged plan explanatory view of a portion A.

[Explanation of symbols]

 1 laminated sheet 2, 5, 21, 23 CPP film 3 cup base paper 3a coating layer 4, 22 barrier layer 20 tape-shaped laminated film 31 opening peripheral member 33 bottom edge Part annular member 50 {paper container 100} container main body 120 {cylindrical body 130} bottom body 140} bonding part 150, 160} edge

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 9/00 B32B 9/00 A 27/10 27/10 27/32 27/32 Z B65D 3/22 B65D 3/22 B 81/34 81 / 34 U

Claims (8)

[Claims] 1. A cylindrical bottom comprising a laminated sheet having a laminated portion mainly composed of a paper layer and having a bonded portion composed of a laminated sheet and having an outer peripheral edge rising downward, The inner peripheral edge and the inner peripheral edge of the outer peripheral edge rising downward from the bottom body are thermally bonded to each other such that the lower edge of the cylindrical body and the lower peripheral edge of the outer peripheral edge of the bottom body are flush with each other. A paper container composed of a container body made of: and a tape-shaped laminated film for covering both the inner and outer edges generated at the bonded portion of the cylindrical body. And a heat-sealing opening peripheral member positioned between the lower edge of the container main body formed by thermal bonding between the lower end of the cylindrical body and the raised outer peripheral edge of the bottom body. The hot melted polypropylene Retorting possible paper container, characterized in that provided by injection molding with a resin. 2. The laminated sheet according to claim 1, wherein the laminated sheet has at least a four-layer structure in which an unstretched polypropylene (CPP) film, a cup base paper, a barrier layer, and an unstretched polypropylene (CPP) film are laminated in this order from the outside of the container. The paper container capable of being subjected to a retort sterilization treatment according to claim 1. 3. The CPP film located on the outside of the container of the CPP film constituting the laminated sheet is a block type or a random type CPP film, and the CPP film located on the side in contact with the contents is a block type CPP film. 2. The film according to claim 1, which is a film.
Or a paper container capable of being subjected to a retort sterilization treatment according to item 2. 4. The laminate sheet according to claim 1, wherein the barrier layer comprises:
The retort sterilizable paper container according to claim 1, 2 or 3, which is any one of a film on which an inorganic compound deposited thin film is formed, a film on which a metal compound deposited thin film is formed, and a barrier plastic film. 5. The cup base paper constituting the laminated sheet,
A diatomaceous earth coat layer on the base paper surface is 12 to 18 g / m
² coated, characterized in that a cup base paper has claim 1, 2, 3 or 4 retorting possible paper container according. 6. The tape-like laminated film according to claim 1, wherein the laminated film is composed of at least three layers laminated in the order of a polypropylene film, a barrier layer and a polypropylene film. Or a paper container capable of being subjected to a retort sterilization treatment according to 5. 7. The barrier layer constituting the tape-shaped laminated film is one of a film on which an inorganic compound vapor-deposited thin film is formed, a film on which a metal compound vapor-deposited thin film is formed, and a barrier plastic film. The paper container according to claim 1, 2, 3, 4, 5, or 6, which can be subjected to a retort sterilization treatment. 8. A polypropylene resin used for the injection molding method, wherein the polypropylene resin used for the opening peripheral member is a block type polypropylene resin having an MFR of 8 to 30. 3,
A paper container capable of being subjected to a retort sterilization treatment according to 4, 5, 6, or 7.