JP2001278241A - Paper-made vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper-made vessel which comprises a cylindrical trunk member and a bottom member approximately in a circular shape erected downward and is easily molded and adaptable as a vessel to use for a longtime preservation. SOLUTION: A thermoplastic resin layer forming an inner layer 22 which constitutes the trunk member 2 is formed in a two-layer structure for which lamination is made, starting from the side contacting with a base 21, by laminating a thermoplastic resin having a low MFR(melt flow rate) serving as a first inner layer 22a and a thermoplastic resin having a high MFR serving as a second inner layer 22b in this order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper container formed by laminating a sheet of paperboard as a base material, wherein an inner layer and an outer layer are formed of a heat-sealable thermoplastic resin, and which is obtained by heat-forming a body member and a bottom member. In particular, the present invention relates to paper cups, paper cans, and the like.

[0002]

2. Description of the Related Art A paper container, such as a paper cup, for storing a beverage such as coffee or juice or a liquid food such as yogurt generally has a cylindrical body member tapering downward and a substantially circular shape. And, the outer peripheral edge is formed of a bottom member that stands upright, the inner surface of the outer peripheral edge of the bottom member is joined to the lower inner surface of the trunk member, and the lower edge of the trunk member is further covered to cover the outer peripheral edge. It has a bottom structure which is bent inward and joined to the outer surface of the outer peripheral edge of the bottom member.

[0003] Here, the layer structure of the body member and the bottom member is generally shown by polyethylene (PE) /
Paperboard / PE or paperboard / PE is often used, and the PE used has a melting point of 105 to 115 ° C. and a density of 0.91.
0.93 g / cm ³ , MFR: 3.0 to 5.0 g / 1
0 min. Is used, and the inner layer and the outer layer are often the same type of PE.

[0004] Depending on the type of the container, a gas barrier layer such as an aluminum foil, a polyester film, or a polyester film on which a metal-deposited thin film layer is formed may be provided between the inner layer PE and the paperboard. Particularly, in the case of a paper cup requiring a barrier property, the thickness of the PE of the inner layer is often set to 50 to 70 μm with emphasis on embedding of steps during molding and pinhole resistance.

As shown in FIGS. 3 (a) and 3 (b), the joining of the inner surface of the lower part of the trunk member and the inner surface of the outer peripheral edge of the bottom member, and the lower end of the trunk member and the outer surface of the outer peripheral edge of the bottom member are respectively performed. The peripheral portion placed on the upper part of the forming mandrel 40 is narrowed and the bottom member 3 erected downward (upward in the figure) is raised to the bottom member side tip portion of the body member 2 wound around the forming mandrel 40 at a high temperature. The heated hot air 50 is sprayed and heated, folded inward using an in-curl mold (not shown), and then knurled (not shown) is applied to the inner surface side of the body member and the inner surface of the bottom member standing upright. Side, the inner surface side of the folded body member and the outer surface side of the raised bottom member are bonded by pressing.

[0006] By the way, from the filling of contents such as hot coffee in a vending machine to the end of use, it takes 10 minutes.
In the case of paper cups for hot coffee for about a minute, the above-mentioned prescription can be sufficient, but recently the contents are filled by food and beverage companies such as natto, yogurt, juice, etc., and consumed after the distribution process There is an increasing need for such containers.

In order to meet such needs, it is necessary to satisfy two conditions at the time of molding the container, that there is no pinhole and that the resin is completely filled in the step. For this reason, the PE thickness on the inner surface side of the body member is increased, or low-density polyethylene (L
DPE), but in the former measure, cost increases due to an increase in the amount of resin used,
The molding temperature must be increased due to an increase in the amount of heat at the time of molding. In the latter method, there is a problem that although the filling of the resin is improved, the risk of pinholes increases.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a paper container comprising a cylindrical body member and a substantially circular, downwardly standing bottom member which can be stored for a long period of time. An object of the present invention is to provide a paper container which can be formed easily and reliably and can be used as a container for long-term storage.

[0009]

Means for Solving the Problems A first invention of the present invention is:
A cylindrical body member having a paperboard base material and a heat-sealable thermoplastic resin layer in the inner layer, and a substantially circular shape having a paperboard base material and a heat-sealable thermoplastic resin layer in the inner layer, and facing downward An upright bottom member, and a paper container made of: a thermoplastic resin layer having a high MFR on a thermoplastic resin having a low MFR from a side in contact with the base material, the thermoplastic resin layer being an inner layer constituting the body member. A paper container having a two-layer structure.

As described above, the inner thermoplastic resin layer constituting the body member has a two-layer structure in which a thermoplastic resin having a high MFR is laminated on a thermoplastic resin having a low MFR from the side in contact with the base material. By using a low MFR thermoplastic resin on the side that is in direct contact with the paperboard as the base material to provide pinhole resistance, and improving the resin filling with a high MFR thermoplastic resin on the bottom member that is in contact with the thermoplastic resin Configuration.

According to a second aspect of the present invention, there is provided the paper container according to the first aspect, wherein the thermoplastic resin is polyethylene.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A paper container according to the present invention will be described by taking a paper cup shown in FIG. 1 as an example. As shown in FIGS. 2A and 2B, the layered structure of each laminated sheet used for the body member 2 and the bottom member 3 of the paper cup is as follows.
As 0, the base material (paperboard) 21 / inner layer 22 and the laminated sheet 30 for the bottom member include an outer layer 33 / base material (paperboard) 31 / inner layer 32. The inner layer 22 used in the body member laminated sheet has a two-layer structure including a first inner layer 22a located on the base material side and a second inner layer 22b located outside the first inner layer 22a.

It is desirable to use the same type of thermoplastic resin for each laminated sheet. For example, LDPE, high density polyethylene resin (HDPE), polypropylene resin and the like can be preferably used. The thermoplastic resin of the inner layer to be formed is the first inner layer 22 in contact with the base material side.
When the MFR of the thermoplastic resin of the second inner layer 22b located outside the MFR of the thermoplastic resin a is set higher, the occurrence of pinholes is smaller than before, and the resin in which the resin is filled in the step portion is excellent. Molding becomes possible.

The laminated sheet 20 for the body member and the laminated sheet 30 for the bottom member are prepared by using a known lamination method such as an extrusion lamination method by forming an inner layer thermoplastic resin and an outer layer thermoplastic resin on the front and back of a paperboard as a base material. It can be manufactured by stacking. At this time, as described above, the thermoplastic resin of the inner layer constituting the body member is the first inner layer 22a in contact with the base material side.
And a second inner layer 22b located outside thereof,
It is important that the thermoplastic resin of the second inner layer 22b has a higher MFR than the thermoplastic resin of the first inner layer 22a.

The laminated sheet thus produced is subjected to operations such as punching and slitting to have a predetermined size and shape.
For example, a paper cup can be produced by obtaining a blank of a body member and a winding of a bottom member, and setting the winding of the blank and the bottom member of the body member on a commonly used paper cup forming machine.

As shown in FIG. 3 (a), the bottom of the paper cup is formed on the inner surface of the lower part of the cylindrical body member 2 at the outer periphery of the bottom member 3 having a substantially circular shape and the outer periphery rising downward. The outer surface is joined, and as shown in FIG. 3B, the lower edge of the body member 2 is bent inward so as to cover the outer peripheral portion,
This is performed by crimping and joining to the inner surface of the outer peripheral edge of the bottom member 3 using a knurl (not shown). At this time, hot air 50 is blown to the lower inner surface of the cylindrical body member 2 and the outer surface of the outer peripheral edge of the bottom member 3 to soften the thermoplastic resin on the inner layer surface of the body member, and to reduce the outer peripheral edge of the bottom member. The thermoplastic resin of the outer layer is softened, and the inner layer surface of the body member bent inward and the outer layer surface of the outer peripheral edge of the bottom member are bonded by thermocompression bonding.

The thermoplastic resin of the inner layer constituting the body member is
From the side in contact with the base material, the M
Since it has a two-layer structure in which thermoplastic resins having a high FR are laminated, when hot air is blown and thermocompression-bonded, pinholes are unlikely to occur, and a sufficient level of resin is buried in the steps.

The same can be said for a paper container comprising a top member and a body member as well as a paper container comprising a bottom member and a body member. Further, the shape of the body member is not limited to the cylindrical shape tapering downward as shown, but may be a cylindrical shape tapering upward as well as a cylindrical shape.

[0019]

EXAMPLES Examples of the present invention will be described below more specifically. <Example 1> First, the basis weight of the substrate 21 was 220 g / m ^2.
Density: 0.92 as inner layer 22 on one side of paper cup base paper
3 g / cm ³ , melting point: 110 ° C., MFR: 3.7 g /
10 min. Mirason 16P (manufactured by Mitsui Petrochemical Co., Ltd.), which is LDPE, having a density of 0.917 g / cm ³ ,
Melting point: 105 ° C, MFR: 8.0 g / 10 min. 11P (manufactured by Mitsui Petrochemical Co., Ltd.), which is an LDPE, was applied to each of the layers in a thickness of 10 μm in this order by an extrusion lamination method.
g / m ² ) 21 / LDPE (10 μm, MFR: 3.
7) 22a / LDPE (10 μm, MFR: 8.0) 2
A laminated sheet 20 for a trunk member having a 2b configuration was produced.

Separately, the basis weight of the substrate 31 is 220 g / m ^2.
Milason 16P, which is the LDPE used at the time of producing the laminated sheet for the body member, was applied to the front and back of the paper cup base paper to a thickness of 20 μm each by an extrusion lamination method.
PE (20 μm, MFR: 3.7) 33 / cup base paper (220 g / m ² ) 31 / LDPE (20 μm, MF
R: 3.7) A laminated sheet 30 for a bottom member having 32 configurations was produced.

The laminated sheet 20 for a trunk member was subjected to processing operations such as punching and slitting to obtain a fan-shaped trunk blank having a predetermined size and shape. The bottom member laminated sheet 30 was slit into a predetermined width to obtain a bottom member wound up.

Using a general paper cup forming machine, first, the body member blank is formed into a cylindrical body member 2 that tapers downward, and the bottom member is wound in a substantially circular shape. It is stamped and formed into a bottom member 3 whose peripheral edge stands upright.

Next, as shown in FIG. 3A, the inner surface of the body member 2 and the outer surface of the bottom member 3 are joined while the outer surface of the outer peripheral edge of the bottom member 3 is joined to the lower inner surface of the body member 2. 320 on the side
Blow hot air 50 ° C.

Next, the lower edge of the body member (which is the upper end in FIG. 3B) is inwardly covered with an incurling mold (not shown) so as to cover the upright outer peripheral portion of the bottom member. The folded back body member and the raised outer peripheral portion of the bottom member are crimped using a knurl (not shown) so that the inner surface of the folded body member is thermally fused to the outer surface of the bottom member so that a stepped portion is formed. A paper cup with a complete bottom structure filled with resin was obtained.

[0025]

As described above, according to the present invention, a paper container which can be stored for a long period of time can be easily formed. The resin thickness can be suppressed to the same level as that of a conventional bender cup, and an increase in the amount of resin can be suppressed.

[Brief description of the drawings]

FIG. 1 is a partially sectional explanatory view showing one embodiment of a paper container of the present invention.

FIGS. 2A and 2B are cross-sectional explanatory views showing one embodiment of a laminated sheet used in the paper container of the present invention, wherein FIG. 2A shows a laminated sheet for a trunk member, and FIG. 2B shows a laminated sheet for a bottom member.

FIG. 3A is a cross-sectional explanatory view showing a state in which an outer surface of an outer peripheral edge of a bottom member is joined to an inner surface of a lower portion of the body member during molding of a paper cup, and FIG. 3B is a lower end edge of the body member; FIG. 10 is a cross-sectional explanatory view showing a state where the portion is folded inward and the folded inner surface of the trunk member is thermally fused to the outer surface of the bottom member.

[Explanation of symbols]

 1 {paper container 2} trunk member 3} bottom member 20} laminated sheet for trunk member 21 {base material, paperboard 22} inner layer 22a {first inner layer 22b} second inner layer 30} bottom member Laminated sheet for base material 31 ‥‥ Base material, paperboard 32 ‥‥ Inner layer 33 ‥‥ Outer layer 40 ‥‥ Molding mandrel 50 ‥‥ Hot air

Claims (2)

[Claims] 1. A substantially cylindrical body member having a paperboard base material and a heat-sealable thermoplastic resin layer in the inner layer, and a substantially circular shape having a paperboard base material and a heat-sealable thermoplastic resin layer in the inner layer. And a bottom member rising downward, comprising: a thermoplastic resin having a low melt flow rate (MFR) from the side in contact with the base material, wherein the thermoplastic resin layer of the inner layer constituting the body member is formed from A paper container characterized by having a two-layer structure in which a thermoplastic resin having a high MFR is laminated thereon. 2. The paper container according to claim 1, wherein said thermoplastic resin is polyethylene.