JP5330927B2 - Barrier insulated paper container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat insulating paper container with barrier properties which prevents a flavor component contained in a content from permeating to the outside of the container, and oxidized and degraded owing to oxygen intruded from the outside of the container and an odor component from moving into the content from the outside of the container. <P>SOLUTION: The body member forming the side wall of the heat insulating paper container with barrier properties is constituted of a heat insulating layer (1), base paper (2), a high melting point polyethylene layer (3), a barrier layer (4) and a sealant layer (5) piled up in this order from the outside of the container. The melting point of the polyethylene resin used for the layer (1) is lower than that of the polyethylene resin used for the layer (3). The container is thermally foamed after it is formed and the composite sheet constituting the body member has at least a resin layer including the barrier layer (4) piled up on the layer (3) formed in advance on the back face of the paper (2) by an extrusion laminate method. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a heat insulating paper container having excellent barrier properties, and in particular, molding a composite sheet having excellent container moldability, suppressing permeation of flavor components contained in contents stored in the container to the outside of the container, and the container The present invention relates to a heat insulating paper container having a barrier property that is effective in suppressing oxidative deterioration of contents due to oxygen intrusion from the outside, and further suppressing the migration of odor components from the outside of the container to the contents.

Conventionally, as a paper container for storing instant noodles, soup, etc., pouring hot water and eating and drinking, a cup-type heat insulating paper container with a foam insulation layer on the outer surface and a polyethylene layer on the inner surface has been widely used It is used.
In such a form of insulated paper container, the barrier performance of the container itself is not considered so much, the dissipation of flavor components contained in ingredients such as powdered soup ingredients and condiments, and oxygen from the outside of the container In order to suppress oxidative degradation due to aging, they are sold by filling them in a soft packaging material such as aluminum foil laminated and packing the filled soft packaging material in a paper container as a subpackaging body. It was.
However, from the viewpoint of waste reduction of the soft packaging material, which is the above-mentioned sub-packaging body, simplification of the contents filling process, convenience for eating and drinking, etc., packaging in which powder soup is directly enclosed in a paper container together with dry noodles Forms of paper container products have been sold. Therefore, improvement of the barrier performance of the paper container itself has been demanded.
Furthermore, since the shelf life of such instant noodles is generally as long as several months or more, there is a need to consider the influence from distribution, sales, and subsequent consumer storage environment. Measures to suppress the migration of odor components from the external environment to the contents have come to be emphasized.
Therefore, as will be described later, several configurations of paper containers laminated with a barrier resin film have been proposed.
On the other hand, a heat insulating paper container having a heat insulating layer foamed on the surface is manufactured by the following process.
(1) Processing of composite sheet: Laminating of front and back surfaces of base paper (2) Punching to predetermined shape: Creation of blank sheet (3) Skive processing as required: Folding of end of body member (4) Paper Container molding: body seal, bottom member bonding, top curl formation (5) Foaming process: Heat foaming of the surface polyethylene layer If necessary, in the process before and after processing of the composite sheet of (1) above, the surface or surface of the base paper Printing is performed on the polyethylene layer.

Therefore, in the heat insulating paper container having this kind of barrier property, the barrier layer is laminated on the surface that becomes the inner surface of the paper container in the processing step of the composite sheet (1).
For example, Japanese Unexamined Patent Application Publication No. 2003-200980 (Patent Document 1) describes a configuration in which an aluminum foil or a barrier plastic film is used as a barrier layer and is combined with a PET film and laminated on a base paper.
Japanese Patent Application Laid-Open No. 2004-231197 (Patent Document 2) proposes a configuration in which a barrier film layer is bonded to a base paper using an adhesive.
From the viewpoint of barrier properties, the method using aluminum foil is the most suitable. However, a paper container using aluminum foil is not the most desirable configuration in terms of recyclability, and is a laminate of plastics with high barrier properties. Is desirable.
In addition, these publications exemplify nylon films, ethylene-vinyl acetate copolymer saponified films, PET films, vapor-deposited films, and the like as barrier film layers. Performance is improved.
However, since the barrier plastic film is generally subjected to stretching treatment or heat treatment and crystallization proceeds, the barrier plastic film has high rigidity.
Therefore, when these films are used in the construction, if there is a skive process in the barrel seal part in the cup molding process, the folded part may be lifted by the repulsive force of the film, which may cause molding failure.
Here, skive processing means that when molding a body member, the surface of the inner end that becomes the bonding portion is scraped from the paper layer portion, and the scraped portion is inverted and bonded to the paper layer side. A processing process.
In addition, in the composite sheet containing the barrier plastic film in the structure, the resilience strength of the sheet itself is also strong, and in the step of forming the top curl part in the cup molding process, the curled part may not be sufficiently wound, This was one of the causes of molding defects. Furthermore, due to the problem of the resilience strength of the sheet itself, there was also a cause of molding failure such that the cylinder seal portion was shifted and molded, or the folded portion at the bottom could open (see FIG. 2). .

As a possible next measure, in order to reduce the rigidity of the barrier plastic film, a method of forming a non-stretched and unheated barrier plastic film and then laminating the film on a substrate is conceivable. .
In an unstretched and unstretched barrier plastic film, the rigidity of the film per unit thickness is lower than that of a stretched film.
However, when the barrier plastic film is formed, the thickness of the film cannot be sufficiently reduced. As a result, the thickness of the composite sheet increases, and it becomes difficult to mold the container with a normal molding machine.
Also, in the processing step of the composite sheet, due to film shrinkage due to heat at the time of film bonding and film elongation due to take-up tension, distortion occurs in the composite sheet after film bonding, and when the composite sheet is punched into a predetermined shape In some cases, twisting curls occur, which makes it difficult to form paper containers.
In addition, since the thickness of the film is large, the quality becomes excessive with respect to the required performance of the barrier property for the contents, and it is difficult to achieve an optimal configuration design, which leads to an increase in cost.
Furthermore, in the case of using a barrier plastic film that has been stretched and heat-treated, an adhesive or an anchor coating agent is used in dry lamination or extrusion lamination, which is a lamination process of the film and base paper or other layers. In addition to the heavy load on the work environment, the odor of the paper container itself due to the residual solvent at the time of poor drying may be regarded as a problem.

JP 2003-200980 A JP 2004231197 A

The problem to be solved by the present invention is to provide a heat insulating paper container having suitable heat insulating performance and barrier performance.
That is, a barrier that can suppress the permeation of flavor components contained in the contents to the outside of the container, the oxidative deterioration of the contents due to oxygen intrusion from the outside of the container, and the migration of odor components from the outside of the container to the contents It is an object to provide a heat-insulating paper container.
It is another object of the present invention to provide the above-mentioned barrier heat insulating paper container that can reduce the process defects and various problems in the paper container molding process from the processing step of the composite sheet to be used.

As a result of intensive studies, the present inventors have found that the body member forming the side wall portion of the paper container has a heat insulating layer (1) / base paper (2) / high melting point polyethylene layer (3) / barrier layer (4) from the outside of the container. / The sealant layer (5) is a composite sheet laminated in this order, wherein the heat insulation layer (1) is made of a polyethylene resin having a lower melting point than the high melting point polyethylene layer (3), and the heat insulation is performed by heat after molding a paper container. In a barrier insulating paper container formed by foaming a layer,
When producing a composite sheet constituting the body member, a resin layer including at least a barrier layer (4) is laminated on the high melting point polyethylene layer (3) previously laminated on the base paper (2) by an extrusion laminating method. made things der is,
The extrusion temperature at the time of extrusion lamination of the barrier layer (4) is 230 ° C. to 280 ° C., the cooling water incoming temperature of the cooling roll is 15 ° C. to 25 ° C., the take-up speed is 80 m / min or more,
In the foaming step for forming the heat insulating layer (1), heat treatment is performed at 110 ° C. to 130 ° C. for 1 minute or more,
The crystallinity of the barrier layer (4) immediately after extrusion laminating the resin layer containing the barrier layer (4) is 20% to 35%,
By forming the heat insulation layer (1) by foaming with heat after the container is formed, the barrier layer (4) has a crystallinity of 35% to 70%. barrier property after step has been found that you increase.

  According to the present invention, while maintaining the flexibility of the composite sheet at the time of paper container molding, the container molding suitability is improved, the high barrier property after molding of the paper container is compatible, and further, the flexible packaging material which is a subpackaging body It is possible to provide a barrier-insulated paper container that considers environmental impacts such as waste reduction and suitability for recycling packaging materials at an appropriate cost.

FIG. 1 is an explanatory view of a composite sheet constituting the body member of the example. 2A and 2B are views showing a conventional barrier heat insulating paper container. FIG. 2A is an overall explanatory view in which one is divided into two at the center and one side is a cross section, and FIG.

First, the method for forming the barrier layer of the present invention will be described.
In the present invention, a method of laminating a barrier layer by an extrusion laminating method is used as a method for solving various problems up to the paper container molding described in the prior art.
As a means for extruding and laminating the barrier layer, a single layer may be extruded, but the co-extrusion laminating method is most preferably used in consideration of adhesiveness with surrounding layers.

By using the extrusion laminating method, the barrier layer can be thinned, and by performing the extrusion laminating process under the predetermined conditions described later, the progress of crystallization of the barrier layer immediately after the laminating process can be reduced, and the rigidity of the barrier layer can be reduced. Can be reduced.
By this, it becomes possible to suppress the rigidity of the barrier layer itself and the composite sheet, so the repulsive force is reduced, the rise of the skive part in the cup molding process and the poor curling of the top curl part, the deviation of the trunk seal part, Molding defects such as opening of the folded portion at the bottom can be prevented.

Also, in the composite sheet processing process, unlike film bonding, there is no film shrinkage due to heat during processing or film elongation due to take-up tension, so twisted curl occurs when the composite sheet is punched into a predetermined shape There is no problem to do.
Furthermore, in the extrusion laminating process of the barrier layer in the barrier heat insulating paper container of the present invention, an adhesive such as an adhesive or an anchor coat agent is unnecessary, and the load on the working environment can be reduced, and the residual at the time of poor drying can be obtained. There is no concern about the odor of the paper container itself due to the solvent.
Furthermore, the thickness of the barrier layer can be controlled according to the required performance of the barrier property for the contents, and it becomes possible to provide a barrier-insulated paper container at an appropriate raw material cost.

In the present invention, since the resin of the barrier layer is extruded and laminated under a predetermined condition, the progress of crystallization in the previous stage of paper container molding is suppressed.
Therefore, the barrier performance is not fully developed.
However, in the foaming step of forming the heat insulation layer 1 by foaming the low melting point polyethylene resin used for the surface heat insulation layer after molding the paper container, the resin of the barrier layer is crystallized by applying a predetermined amount of heat described below. Progresses and exhibits high barrier performance. At the same time, the rigidity of the barrier layer is increased and the strength of the entire paper container is improved.

By the way, regarding the extrusion lamination of barrier resin, many manufacturing methods have been proposed so far.
For example, regarding a multilayer structure using a saponified ethylene-vinyl acetate copolymer, JP-B-5-72868, JP-A-7-16993, JP-B-6-55485, JP-A-2004-181752 The gazette etc. are mentioned.
However, the manufacturing methods presented in these documents are intended to maintain the adhesion to the base paper and the barrier performance, and do not take into account the structural design of the heat insulating cup including the foaming process.

Therefore, even if a low melting point polyethylene resin that forms a heat insulating layer is disposed on the opposite side of the base paper on which these barrier layers are laminated, the required characteristics and processability of the barrier heat insulating paper container cannot be satisfied.
In other words, poor foaming of low melting point polyethylene resin in the foaming process after container molding, container deformation due to thermal contraction of other resin layers, and poor container molding due to excessive progress of crystallization of the barrier layer in the composite sheet processing process occur. Sometimes. In addition, a failure may occur in the progress of crystallization of the barrier layer in the heat treatment during the foaming process, resulting in insufficient barrier performance.

Next, each component used for the barrier heat insulating paper container of the present invention will be described (see FIG. 1).
First, the heat insulating layer (1) on the surface is provided by laminating a low melting point polyethylene resin on the surface side of the base paper (2) by extrusion lamination.
As the low melting point polyethylene resin forming the heat insulating layer (1) on the surface, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), metallocene LLDPE polymerized using a metallocene catalyst, and the like can be used. These may be blended as appropriate.

The low-melting polyethylene may have a lower melting point than the high-melting polyethylene layer (3) described later, and a melting point of 100 ° C. to 115 ° C. is preferably used.
When the melting point exceeds 115 ° C., the resin is difficult to melt in the foaming step, and foamability may be deteriorated.
When the melting point is lower than 100 ° C., the low melting point polyethylene sticks to the cooling roll in the laminating process of the composite sheet, and the front and back surfaces of the composite sheet may cause blocking in the process up to the subsequent molding of the paper container. At the same time, when hot water is poured when the paper container is used for eating and drinking, the foamed heat insulation layer is softened and crushed, which may reduce the heat insulation.

Further, the MFR of the low melting point polyethylene is desirably in the range of 3 g / 10 min to 20 g / 10 min.
If the MFR is lower than 3 g / 10 min, bubbles may be repelled during heating in the foaming step, making it difficult to obtain a good foamed state.
If the MFR exceeds 20 g / 10 min, the foamed bubbles during heating in the foaming process may cause re-aggregation due to residual heat, and the thickness of the foamed layer may decrease.
A more preferred range is from 5 g / 10 min to 15 g / 10 min.

The thickness of the low-melting-point polyethylene layer forming the heat insulating layer (1) is preferably 30 to 100 μ before foaming.
More preferably, it is in the range of 40 μ to 80 μ.
When the thickness of the low melting point polyethylene layer is less than 30 μm, a heat insulating effect sufficient as a paper container may not be obtained due to insufficient thickness of the heat insulating layer (1) after foaming.
If the thickness of the low melting point polyethylene layer exceeds 100 μm, the strength of the low melting point polyethylene layer itself may exceed the volatile vapor pressure of the base paper moisture during heating in the foaming step, and foaming may be suppressed.

Further, when printing is performed in a later step on the low melting point polyethylene layer forming the heat insulating layer (1), the surface of the low melting point polyethylene layer is subjected to corona treatment or flame treatment to enhance wettability. It is preferable.
In that case, the wetting index is preferably 36 dynes to 43 dynes immediately after processing.
If the wetting index is less than 36 dynes, ink adhesion failure may occur during printing, and if it exceeds 43 dynes, pinholes or scorching may occur in the composite sheet.

The base paper (2) is made from pulp components such as wood pulp such as conifer pulp and hardwood pulp, and non-wood pulp such as kenaf, bamboo, and bagasse. The sizing agent and wet strength agent However, it is desirable that the basis weight is 100 to 500 g / m ² , more preferably 150 to 400 g / m ² .

If the basis weight is less than 100 g / m ² , the absolute amount of moisture contained in the base paper may be insufficient, and foaming of the low-melting polyethylene that becomes the heat insulating layer (1) on the surface may be insufficient. When the basis weight exceeds 500 g / m ² , the rigidity of the base paper becomes strong, which may hinder the formability of the paper container.

The moisture content of the base paper is preferably in the range of 6.0 to 8.5%.
If the water content of the base paper is less than 6.0%, the top curl in the paper container molding process may cause cracking of the paper layer, and the water in the base paper cannot be sufficiently evaporated in the foaming process, resulting in poor foaming. Sometimes.
If the water content exceeds 8.5%, the strength of the base paper may be reduced, and the dent and buckling of the paper container may occur. Also, in the foaming process for forming the heat insulating layer (1), the low melting point polyethylene is foamed. The cell may bounce or may be partially foamed and become over-foamed.

If necessary, printing can be performed on the surface side of the base paper (2) before laminating the low melting point polyethylene for forming the heat insulating layer (1).
The high-melting polyethylene layer (3) is a layer that prevents peeling between the base paper (2) and the resin layer on the inner surface side during the heat treatment in the foaming step and relieves container deformation due to resin shrinkage. The resin used for the high melting point polyethylene layer (3) is appropriately selected from low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, metallocene LLDPE polymerized using a metallocene catalyst, and the like. These may be blended and used as necessary, but they must have a higher melting point than the low melting point polyethylene forming the heat insulating layer (1).

The melting point difference is desirably 5 ° C. or higher, more preferably 10 ° C. or higher.
When the melting point is the same as or close to that of low-melting polyethylene, swelling occurs between the base paper and the high-melting polyethylene layer (3) during the heat treatment in the foaming process, or wrinkled distortion due to resin shrinkage occurs. May occur.

On the other hand, when the melting point of the high-melting polyethylene resin exceeds 140 ° C., when the high-melting polyethylene resin is formed by the extrusion laminating method in the composite sheet processing step, the processing stability may be lowered. At the same time, adhesion failure between the base paper (2) and the high melting point polyethylene layer (3) may occur.
From these things, it is preferable that melting | fusing point of resin used for a high melting point polyethylene layer (3) is a thing of 105 to 140 degreeC. More desirably, the temperature is 110 ° C to 135 ° C.

This high melting point polyethylene layer (3) needs to be formed in advance on the back surface of the base paper (2) by an extrusion laminating method or the like before extrusion laminating the barrier layer (4) in the composite sheet processing step for the reason described later. There is.
Moreover, it is preferable that the thickness shall be 10 micrometers-40 micrometers.
When the thickness is less than 10 μm, film breakage may occur during the extrusion laminating process for forming the high melting point polyethylene layer (3), and adhesion failure with the base paper may occur.
If it exceeds 40 μm, the composite sheet becomes thick and the rigidity is increased, so that molding failure may occur in the paper container molding process.

As the barrier resin used for the barrier layer (4), a resin suitable for extrusion laminating can be appropriately selected and used.
From the point of suitability for extrusion lamination, nylon 6, nylon 6-6, metaxylenediamine and adipic acid copolymer, polyamide resin such as amorphous nylon resin, ethylene-vinyl acetate copolymer saponified product (hereinafter referred to as EVOH) The amorphous nylon resin is easily softened by the heat treatment in the foaming process, and can be said to be unsuitable for the use of the present invention. From the viewpoint of barrier performance, a saponified ethylene-vinyl acetate copolymer is most preferably used.

The barrier layer may be a hybrid of a mixture of these resins or an inorganic filler.
The saponified ethylene-vinyl acetate copolymer has a melt index at 190 ° C. of 1 g / 10 min to 30 g / 10 min, more preferably 3 g / 10 min to 20 g / 10 min, from the viewpoint of suitability for extrusion lamination.
If the melt index is outside this range, the film-forming stability may be lowered in the extrusion laminating process of the barrier layer (4).

Moreover, it is preferable that an ethylene content is 20-50 mol% from a viewpoint of barrier property.
When the ethylene content is 50 mol% or more, the barrier layer must be thickened due to insufficient barrier performance, and as a result, the paper container moldability may be reduced.
When the ethylene content is 20 mol% or less, the barrier performance is sufficient, but the thermal stability becomes poor, so that the film-forming stability is lowered and the generation of thermally deteriorated products in the extrusion laminating process of the barrier layer (4). Tend to cause.

The thickness of the barrier layer (4) can be set to an arbitrary thickness from the necessary characteristics for the contents. If the thickness is less than 1 μm, the barrier layer (4) is extruded and laminated in the composite sheet processing step. Since there is a possibility of cutting, it is preferable that the thickness is 1 μm or more.
On the other hand, if the thickness exceeds 20 μm, the thickness of the composite sheet becomes thick and the rigidity becomes strong, which may cause molding failure in the paper container molding process.

In particular, when an ethylene-vinyl acetate copolymer saponified product is used as the barrier layer (4), if it exceeds 20 μm, the barrier performance for the contents becomes excessive quality, and the cost of raw materials is also increased. It becomes difficult to provide paper containers. Therefore, the thickness range of the barrier layer (4) is preferably in the range of 1 μm to 20 μm.
Further, as described above, the barrier layer (4) needs to be formed by a method of laminating by an extrusion laminating method. As a means of extrusion lamination of the barrier layer (4), it may be extruded as a single layer, but the barrier layer (4) should be made as thin as possible according to the barrier performance required for the contents, In view of the adhesive property, coextrusion laminating is most preferably used.

  As a coextrusion laminating method, a method of extruding in a three-layer structure of adhesive resin / barrier resin / adhesive resin on a high-melting polyethylene layer (4) previously provided on the back surface of the base paper (2), adhesion Method of extruding in a four-layer configuration of an adhesive resin / barrier resin / adhesive resin / sealant layer (5), a five-layer configuration of thermoplastic resin layer / adhesive resin / barrier resin / adhesive resin / thermoplastic resin layer And a method of extruding with a five-layer structure of thermoplastic resin layer / adhesive resin / barrier resin / adhesive resin / sealant layer (5).

Here, the adhesive resin is a resin that can be bonded to both the barrier resin and the high-melting polyethylene layer (3) and the barrier resin and the sealant layer (5) or the thermoplastic resin layer. Mainly made of polyolefin resin such as linear low density polyethylene modified with acid anhydrides such as maleic anhydride, or copolymerized with vinyl acetate, acrylic acid, acrylic esters and olefins. is there.
These adhesive resins may be used alone as an adhesive resin layer, or may be blended with any of the above resins, and may be blended with low density polyethylene or linear low density polyethylene. Also good.

The thickness of the adhesive resin layer can be arbitrarily determined according to the laminating characteristics and the adhesive strength, but is preferably in the range of 1 μ to 15 μ.
If the thickness of the adhesive resin layer is less than 1 μm, there is a possibility that the adhesive resin layer may be broken in the co-extrusion laminating process of the barrier layer (4) in the composite sheet processing step, or a poor adhesion may occur.
On the other hand, when the thickness exceeds 15 μm, the thickness of the composite sheet becomes thick and the rigidity becomes strong, which may cause molding failure in the paper container molding process.

As the thermoplastic resin layer, the same type of resin as the sealant layer (5) described below can be used, and the same resin as that of the sealant layer (5) may be provided.
The sealant layer (5) is a layer that is required for bonding the body members or between the body member and the bottom member in the paper container molding process, and is a layer that is in direct contact with the contents.
The resin used for the sealant layer (5) can be appropriately selected from low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, metallocene LLDPE polymerized using a metallocene catalyst, and the like. These may be blended as necessary.

The thickness of the sealant layer (5) can be arbitrarily determined according to the shape and size of the paper container, the basis weight of the base paper used, and the required characteristics of the paper container molding machine.
In addition, as a lamination method, a method of extruding and laminating the sealant layer (5) alone, a method of co-extrusion laminating at the same time as the barrier layer (4), and sandlamming the film-formed sealant layer (5) with a thermoplastic resin. For example, a method of simultaneously laminating the sealant layer (5) formed into a film when the barrier layer is coextruded and laminated can be used.

Next, the processing steps and processing conditions of the composite sheet used for the barrier heat insulating paper container of the present invention will be described.
First, when processing the composite sheet used for the barrier heat insulating paper container of the present invention, a resin layer containing a high melting point polyethylene layer (3) and a barrier layer (4) is sequentially laminated on the back surface of the base paper (2). There is a need.

When extruding and laminating the resin layer containing the barrier layer (4) to the base paper (2), the high melting point polyethylene layer (3) is formed in advance on the base paper (2) surface, so that it is directly laminated to the base paper (2). Compared with the case where it does, it becomes possible to make low extrusion temperature required in order to maintain a lamination strength favorable.
As a result, crystallization of the barrier layer can be suppressed under the processing conditions described later.

  Lamination of the sealant layer (5) may be performed by coextrusion laminating simultaneously with the lamination of the barrier layer (4) or after lamination of the barrier layer (4). Lamination of the low-melting-point polyethylene layer forming the heat insulating layer (1) can take any processing order including before and after the above-described steps.

Next, the processing conditions of the barrier layer (4) during the process of processing the composite sheet used for the barrier insulating paper container of the present invention will be described.
As described above, the barrier layer (4) needs to be formed by a method of laminating by an extrusion laminating method.

As a means for extruding and laminating the barrier layer (4), a single layer may be extruded. However, as described above, a method of coextrusion laminating a plurality of resin layers including the barrier layer (4) is most preferably used.
However, in this case, in order to reduce the rigidity of the barrier layer (4) from the viewpoint of container moldability during skiving, the progress of crystallization of the barrier layer (4) must be suppressed, and the base Processing conditions for maintaining the adhesion between the high melting point polyethylene layer (3) and the barrier layer (4) must be taken.

For this purpose, the resin layer containing the barrier layer (4) is extruded from the extrusion laminator at the lowest possible temperature, brought into contact with the high-melting-point polyethylene layer (3) as a base in a short time, and then rapidly heated by a cooling roll. It is necessary to cool below the glass transition temperature.
As processing conditions suitable for satisfying the above proposition, it is preferable that the processing temperature at the time of extrusion lamination is 280 ° C. or lower, the cooling water incoming temperature of the cooling roll is 25 ° C. or lower, and the take-up speed is 80 m / min or higher.
The processing temperature refers to the temperature of the molten resin layer when the resin flows out from the T die.

As for the processing temperature, if the temperature is higher than 280 ° C., the resin cannot be sufficiently cooled, and the degree of crystallinity of the barrier layer immediately after lamination becomes high, and it is not preferable from the viewpoint of suppressing the generation of thermal degradation products.
On the other hand, when the temperature is lower than 230 ° C., adhesion with the high-melting polyethylene layer (3) serving as a base tends to be insufficient. For this reason, the range of desirable processing temperature is the range of 230 to 280 degreeC.

Regarding the cooling water incoming temperature of the cooling ring, it is generally said that the higher the temperature, the better the adhesion to the base.
However, in the present invention, since it is necessary to rapidly cool the resin layer including the barrier layer (4) below the glass transition temperature of the barrier resin to suppress the progress of crystallization of the barrier resin, It is desirable that the water temperature is 25 ° C. or lower.
On the other hand, if the cooling water incoming temperature of the cooling ool is too low, adhesion to the high-melting polyethylene layer (3) serving as a base may be insufficient.
For this reason, the range of desirable cooling water incoming water temperature is the range of 15 to 25 degreeC, More preferably, it is 17 to 23 degreeC.

  Regarding the take-off speed of the extrusion laminator, when the take-off speed is slow, the time until the resin layer containing the molten barrier layer (4) comes out of the T die and comes into contact with the high-melting-point polyethylene layer (3) (that is, Air gap passage time) becomes longer.

In the present invention, as described above, since the processing temperature during extrusion lamination of the resin layer including the barrier layer (4) is performed in a low temperature range of 230 ° C. to 280 ° C., if the air gap passage time is too long, the molten film May be cooled in the air, and sufficient adhesive strength with the high melting point polyethylene layer (3) as a base may not be obtained.
For this reason, the take-up speed is preferably 80 m / min or more, more preferably 100 m / min or more.
Further, the time until the resin layer including the molten barrier layer (4) comes into contact with the high-melting polyethylene layer (3) as a base and is cooled is shortened so that the crystallization does not proceed as much as possible. Therefore, it is preferable to process at high speed.

On the other hand, when the take-up speed is too high, the cooling effect with the cooling roll becomes insufficient, and the temperature higher than the glass transition temperature of the barrier resin may remain maintained.
For example, when the take-up speed exceeds 300 m / min, it is necessary to consider the cooling efficiency. In such a case, measures such as using equipment having a cooling roll with a large roll diameter are taken.

The composite sheet used in the present invention is manufactured by using the above-described constituent materials and the above-described processing steps and processing conditions.
By taking the extrusion laminating conditions of the resin layer including the barrier layer (4), the progress of crystallization of the barrier layer (4) is suppressed, and the crystallinity thereof is 20% to 35 immediately after laminating. %, A low level can be maintained.

Here, in Japanese Patent Publication No. 6-55485 described above, a configuration similar to the present invention is presented.
The configuration presented in Japanese Examined Patent Publication No. 6-55485 is a configuration of LDPE / base paper / LDPE / LDPE / adhesive resin / EVOH / adhesive resin / LDPE, which is formed on an LDPE layer previously provided on the base paper surface. It describes that coextrusion laminating is performed with a three-kind five-layer structure of / adhesive resin / EVOH / adhesive resin / LDPE.

  However, as described above, the manufacturing method presented here relates to a method for manufacturing a barrier board for the purpose of maintaining adhesiveness with a base paper and barrier performance, and includes a foaming step as in the present invention. No consideration is given to the cup design.

First, it is described that an LDPE layer is provided in advance on the base paper, but the container deformation due to peeling or resin shrinkage between the base paper and the resin layer on the inner surface side during the heat treatment in the foaming step is described. No consideration is given to the high-melting polyethylene layer (3).
Secondly, it is described that coextrusion laminating is performed on the LDPE layer in a three-layer five-layer configuration of LDPE / adhesive resin / EVOH / adhesive resin / LDPE. The necessity and conditions for suppressing the crystallization of the EVOH layer are not considered in order to improve the processability in the molding process.

In the text of the patent specification, there is a description of “processing temperature lower than 600 ° F.”. However, in high temperature processing that is substantially close to 600 ° F. = 315.6 ° C., crystallization of EVOH resin is not possible. It tends to progress.
Therefore, even if a low melting point polyethylene resin that forms a heat insulating layer is arranged on the opposite side of the base paper laminated with a barrier layer as in the patent, the container moldability required for the barrier heat insulating paper container is satisfied. Will be difficult.

The composite sheet of the present invention obtained as described above is stamped into a predetermined size and shape after printing and is subjected to a folding skive process at the end of the body member as necessary, thereby forming a paper container. to go into.
In the paper container molding process, in the case of a cup-type container, the end portions of the body member made from the composite sheet of the present invention are bonded to each other, joined to the bottom member, and the top curl portion is entangled.

By using the composite sheet of the present invention, the above-mentioned problems in the paper container manufacturing process can be solved and good moldability can be obtained.
The paper container molded in this way is then subjected to a foaming process of the surface low melting point polyethylene in order to form the heat insulating layer (1).

In the foaming step, the melting point is higher than the melting point of the low melting point polyethylene generally used for the heat insulating layer (1) disposed on the surface of the base paper, and has the highest melting point among the resin layers disposed on the inner surface side. Heat treatment is performed at a temperature lower than the melting point of the resin.
The heat treatment conditions are determined by the form of the oven heating apparatus such as a tunnel type used in the foaming process and the apparatus specifications.

In other words, when the oven furnace is short or when the line speed is high and the heating time is short, the heat treatment is short on the high temperature side, and when the oven furnace is long or the line speed is slow and the heating time is long, the temperature is low. In many cases, long-side heat treatment conditions are used on the side.
In the present invention, in the foaming step after forming the paper container, the heat insulating layer (1) is foamed, and at the same time, the barrier layer (4) is sufficiently crystallized to improve the barrier property of the paper container product. It is a feature. Therefore, it is desirable that the heat treatment conditions of this foaming step be performed in the vicinity of a temperature condition where the crystallization rate of the barrier resin used for the barrier layer (4) is the fastest.

That is, when the saponified ethylene-vinyl acetate copolymer is used as the barrier layer (4), the peak temperature at which the crystallization rate of the saponified ethylene-vinyl acetate copolymer is the fastest is around 120 ° C. It is desirable to perform the heat treatment of the foaming process in a temperature range of 10 ° C. before and after that. Therefore, the heating temperature in the foaming step is preferably 110 ° C to 130 ° C, more preferably 115 ° C to 125 ° C.
The heating time is 1 minute or more, more preferably 2 minutes or more.

In the barrier heat insulating paper container of the present invention that has undergone the foaming process under such heat treatment conditions, the crystallinity of the barrier layer (4) is improved to 35% to 70% compared to before the foaming process, and an excellent barrier The performance will be demonstrated.
At this time, the present invention is characterized in that a high melting point polyethylene layer (3) having a melting point higher than that of the low melting point polyethylene used for the heat insulating layer (1) is provided.

The high melting point polyethylene layer (3) may be softened during the heat treatment, but the presence of this layer causes the peeling between the base paper (2) and the resin layer on the inner surface side during the heat treatment. While preventing, the container deformation | transformation by resin shrinkage accompanying the crystallization progress of a barrier layer (4) can be relieved.
Therefore, the heat treatment condition in the foaming step may be a temperature exceeding the melting point of the high melting point polyethylene layer (3).

As described above, the barrier insulating paper container of the present invention can be obtained. As described above, the barrier heat insulating paper container of the present invention can be molded under good container molding suitability, has a suitable heat insulating performance, and has an excellent barrier performance.
In the case of a cup-type paper container, the bottom member to be joined to the barrel member is also provided with a better moldability by adopting a configuration in which the low melting point polyethylene of the surface heat insulating layer (1) of the barrel member is not disposed. It is also possible to provide a paper container having a barrier performance.

[Embodiment]
The barrier insulating paper container of the present invention will be described more specifically based on examples below, but the present invention is not limited to these examples.
In addition, when evaluating the following Examples and Comparative Examples, each evaluation item was performed based on the following evaluation and measurement methods.

<Molding defect rate>
Based on the input quantity to the post-process of the blank sheet for the cylinder member for paper container molding obtained by punching the composite sheet created in the following examples and comparative examples into a predetermined shape, in the subsequent skive process and paper container molding process The ratio of the total number of defective products generated was defined as the molding defect rate.

In the skive process, peeling or floating of the skive folded portion was caused to be defective when 1 mm or more of bending was generated.
In the paper container molding process, a part where the deformation of the joint part of each member or the winding of the top curl part is less than one round, or a part where wrinkles or buckling occurred in the body part was regarded as defective.

<Oxygen permeability>
In the following examples and comparative examples, a paper container prepared in the following example is provided with a heat insulating layer through a foaming process, and after making the heat insulating paper container, a cover material composed of paper / LDPE / aluminum foil / LDPE is placed on the outside of the container. In this way, a sealed container was prepared by adhering to the opening of the paper container by heat sealing.

Moreover, about what measured oxygen permeability in the unfoamed state, the same lid | cover material was adhere | attached on the paper container, without forming a heat insulation layer without passing through a foaming process, and the sealed container was created.
The method described in JIS K7126 (isobaric method) under conditions of 20 ° C.-65% RH using MOCON-OXTRAN 2/20 model manufactured by Modern Control Co., Ltd. after conditioning the sealed container at 20 ° C. and 65% RH for 1 week. It measured according to.

<P-xylene permeability>
A paper container containing 100 g of p-xylene in a container after the foaming process prepared in the same manner as for the measurement of oxygen permeability, and having a cover material composed of paper / LDPE / aluminum foil / LDPE with the paper surface facing the outside of the container. A hermetic container was prepared by adhering to the opening of the film by heat sealing.
The sample was stored in an environment of 20 ° C. and 65% RH, and the permeation amount was measured by a gravimetric method.

<Crystallinity of saponified ethylene-vinyl acetate copolymer layer>
In the following Examples and Comparative Examples, when a composite sheet was prepared, a barrier layer was laminated by a co-extrusion laminating method, and instead of an adhesive resin extruded on both sides of the barrier resin layer, LLDPE resin 08L51A Except for using (trade name, manufactured by Tosoh Corporation), processing was performed under the same conditions as in each of the examples and comparative examples, and a composite sheet for measuring crystallinity was created.

The LLDPE layer and the barrier resin layer of the composite sheet were peeled off to take out the barrier resin alone, and used as a sample for measuring the crystallinity of the barrier layer immediately after lamination.
Further, the crystallinity measurement sheet container was prepared by performing the paper container molding and the heat treatment in the foaming process using the above-mentioned composite sheet for measuring the crystallinity. The LLDPE layer and the barrier resin layer of the body member of the paper container thus prepared were peeled to take out the barrier resin alone, and used as a sample for measuring the crystallinity of the barrier layer after foaming the heat insulating layer.

Using the single layer sample obtained as described above, a rotational anti-cathode X-ray generator RU-300 (D0201 type, manufactured by Rigaku Denki Co., Ltd.) was used, and the crystallinity was determined by X-ray diffraction.
Various resins used in Examples and Comparative Examples and their physical property values are shown in Table 1.

Petrocene LW-04 (15 μ) was extruded and laminated as a high melting point polyethylene layer on the back side of a base paper of a glass having a basis weight of 320 g / m ² (trade name, manufactured by Tokyo Paper Industries Co., Ltd.), and an adhesive resin ( A resin layer including a barrier layer having a three-layer structure of 5 μ) / barrier resin (5 μ) / adhesive resin (5 μ) was coextruded and laminated.

  At this time, ADMER: SF741 was used as the adhesive resin, and EVOH: C109B was used as the barrier resin. Further, the extrusion processing temperature at the time of coextrusion laminating was 250 ° C., the cooling water entering temperature of the cooling roll was 23 ° C., and the take-up speed was 100 m / min.

  A low melting point polyethylene resin P213 (70 μ) forming a heat insulating layer on the base paper surface of the laminated product and a resin LW-04 (30 μ) serving as a sealant layer on the adhesive resin surface were laminated by extrusion lamination to prepare a composite sheet. .

  The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine. In this case, as the bottom member, a material that does not laminate the surface side low melting point polyethylene P213 of the composite sheet was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 200 seconds to foam the surface low-melting polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

Petrocene LW-04 (15 μ) was extruded and laminated as a high melting point polyethylene layer on the back side of a ² cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 250 g / m ² , and an adhesive resin (5 μm) on the LW-04 surface. ) / Barrier resin (5μ) / adhesive resin (5μ) / sealant layer (10μ), and a resin layer including the barrier layer was coextruded and laminated.

At this time, ADMER: SF741 was used as the adhesive resin, EVOH: C109B was used as the barrier resin, and L2340 was used as the sealant layer resin.
Further, the extrusion processing temperature at the time of coextrusion laminating was 240 ° C., the cooling water entering temperature of the cooling roll was 18 ° C., and the take-up speed was 120 m / min.

A low melting point polyethylene resin 07C03A (40 μm) for forming a heat insulating layer on the base paper surface of the laminated product was laminated by extrusion lamination to prepare a composite sheet.
The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material that does not laminate the above-mentioned composite sheet on the surface side low melting point polyethylene 07C03A was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 80 seconds to foam the surface low-melting-point polyethylene to form a heat-insulating layer, thereby producing a barrier-type heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

Low-melting polyethylene resin LC701 (50μ) forming a heat insulating layer on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ² , and Petrocene LW-01 (15 μm) as a high-melting polyethylene layer on the back surface. ) Is extruded and laminated on the LW-01 surface in a five-layer structure of thermoplastic resin (15μ) / adhesive resin (5μ) / barrier resin (5μ) / adhesive resin (5μ) / sealant layer (15μ). The resin layer including the barrier layer was coextruded and laminated.

  At this time, ADMER: SF741 was used as the adhesive resin, EVOH: C109B was used as the barrier resin, and LW-01 was distributed and used for both the thermoplastic resin and the sealant layer. The extrusion temperature during coextrusion laminating was 270 ° C., the cooling water inlet temperature of the cooling roll was 20 ° C., and the take-up speed was 80 m / min.

The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine. In this case, as the bottom member, a material having the same configuration as that of the above composite sheet was used except that the base paper of the composite sheet was 220 g / m ² and the surface-side low melting point polyethylene LC701 was not laminated.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 125 ° C. for 180 seconds to foam the surface low-melting polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

Petrocene LW-04 (15 μ) was extruded and laminated as a high melting point polyethylene layer on the back of a base paper of a glass having a basis weight of 320 g / m ² (trade name, manufactured by Tokyo Paper Industries Co., Ltd.), and a thermoplastic resin ( A resin layer including a barrier layer was coextruded and laminated in a five-layer structure of 10 μ) / adhesive resin (5 μ) / barrier resin (5 μ) / adhesive resin (5 μ) / thermoplastic resin layer (10 μ).

At this time, ADMER: NF847 was used as the adhesive resin, EVOH: C109B was used as the barrier resin, and P204 was used as the thermoplastic resin. Further, the extrusion processing temperature at the time of coextrusion laminating was 250 ° C., the cooling water entering temperature of the cooling roll was 25 ° C., and the take-up speed was 100 m / min.
A low melting point polyethylene resin P213 (60 μ) for forming a heat insulating layer on the base paper surface of the laminated product and a resin LW-04 (30 μ) as a sealant layer on the thermoplastic resin surface were laminated by extrusion lamination to prepare a composite sheet. .

The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material that does not laminate the surface side low melting point polyethylene P213 of the composite sheet was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 115 ° C. for 240 seconds to foam the surface low-melting-point polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

A low melting point polyethylene resin LC701 (50μ) that forms a heat insulating layer on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ² and L2340 (15μ) as a high melting point polyethylene layer are extruded on the back side. Laminated.
On the L2340 surface of the laminated product, a resin layer containing a barrier layer having a three-layer structure of adhesive resin (5 μ) / barrier resin (5 μ) / adhesive resin (5 μ) is coextruded and simultaneously laminated with a sealant layer The resulting polyethylene film “Suzuron L N280” (trade name, manufactured by Aicero Chemical Co., Ltd., thickness 30 μm) was laminated by a sandwich lamination method to prepare a composite sheet.

At this time, ADMER: SF741 was used as the adhesive resin, and EVOH: C109B was used as the barrier resin.
Further, the extrusion processing temperature at the time of coextrusion laminating was 250 ° C., the cooling water entering temperature of the cooling roll was 20 ° C., and the take-up speed was 120 m / min.
The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In addition, as the bottom member, a material having the same configuration was used except that the base sheet of the composite sheet was 220 g / m ² and the surface-side low melting point polyethylene LC701 was not laminated.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 125 ° C. for 150 seconds to foam the low-melting-point polyethylene on the surface to form a heat-insulating layer, thereby producing a barrier heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

[Comparative Example 1]
A low melting point polyethylene resin P213 (70 μ) forming a heat insulating layer on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ² , and Petrocene LW-04 (30 μm) as a high melting point polyethylene layer on the back surface. ) Was extruded and laminated to create a composite sheet.

The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material that does not laminate the surface side low melting point polyethylene P213 of the composite sheet was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 200 seconds to foam the low-melting-point polyethylene on the surface, and a heat-insulating layer was formed to prepare a heat-insulating paper container.
Table 2 shows the measurement results of the molding defect rate, the oxygen permeability and the organic matter permeability after the heat insulation paper container was formed in the process of molding this heat insulation paper container.

[Comparative Example 2]
LW-04 (30μ) was extruded and laminated on one side of a PET film “Espet Film E5200” (trade name, Toyobo Co., Ltd., 12μ) using a two-component curable isocyanate anchor coating agent. LW-04 (15 μm) was extruded and laminated using a liquid curable isocyanate anchor coating agent to prepare a composite film.

A low melting point polyethylene resin P213 (70 μm) for forming a heat insulating layer is extruded and laminated on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ² , and the above composite film LW-04 ( The composite sheet was prepared by sandwich lamination with LW-04 (15 μ) so that the 15 μ) surface was on the base paper side.

The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material that does not laminate the surface side low melting point polyethylene P213 of the composite sheet was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 200 seconds to foam the surface low-melting polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 2 shows the measurement results of the molding defect rate, the oxygen permeability and the organic matter permeability after the heat insulation paper container was formed in the process of molding this heat insulation paper container.

[Comparative Example 3]
Polyethylene film “Suzuron L N280” (trade name, Aicero Chemical Co., Ltd.) using a two-component curable isocyanate-based dorami laminate adhesive on one side of EVOH film “Eval EF-XL” (trade name, manufactured by Kuraray Co., Ltd., 12 μm) Manufactured, 30 μm thick), and LW-04 (15 μm) was extruded and laminated on the opposite side using a two-component curable isocyanate anchor coating agent to prepare a composite film.

A low melting point polyethylene resin P213 (70 μm) for forming a heat insulating layer is extruded and laminated on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ² , and the above composite film LW-04 ( The composite sheet was prepared by sandwich lamination with LW-04 (15 μ) so that the 15 μ) surface was on the base paper side.

  The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine. In this case, as the bottom member, a material that does not laminate the surface side low melting point polyethylene P213 of the composite sheet was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 200 seconds to foam the surface low-melting polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 2 shows the measurement results of the molding defect rate, the oxygen permeability and the organic matter permeability after the heat insulation paper container was formed in the process of molding this heat insulation paper container.

[Comparative Example 4]
A low melting point polyethylene resin LC701 (50 μ) for forming a heat insulating layer on the surface of a cup base paper (trade name, manufactured by Tokyo Paper Industries Co., Ltd.) having a basis weight of 320 g / m ^{2, and} a thermoplastic resin (15 μ) / adhesive resin ( The resin layer including the barrier layer was coextruded and laminated in a five-layer structure of 5 μ) / barrier resin (5 μ) / adhesive resin (5 μ) / sealant layer (15 μ) to prepare a composite sheet.

  At this time, ADMER: SF741 was used as the adhesive resin, EVOH: C109B was used as the barrier resin, and LW-04 was distributed and used for both the thermoplastic resin and the sealant layer. Moreover, the extrusion processing temperature at the time of coextrusion lamination processing was 330 degreeC, the cooling water incoming temperature of the cooling roll was 23 degreeC, and the taking-up speed | rate was 80 m / min.

The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material having the same configuration as that of the above composite sheet was used except that the base paper of the composite sheet was 220 g / m ² and the surface-side low melting point polyethylene LC701 was not laminated.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 125 ° C. for 180 seconds to foam the surface low-melting polyethylene, and a heat-insulating layer was formed to prepare a barrier heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

[Comparative Example 5]
In the case of co-extrusion laminating of the resin layer including the barrier layer, the composite was made in the same manner as in Example 2 except that the extrusion processing temperature was 315 ° C., the cooling water cooling water inlet temperature was 30 ° C., and the take-up speed was 50 m / min. Created a sheet.
The composite sheet was punched into the shape of a fan-shaped cup-molding blank sheet, and a skive process having a width of 5 mm was applied to one end portion thereof, and a cup-type paper container with a top curl having a capacity of 240 ml was molded by a cup molding machine.
In this case, as the bottom member, a material that does not laminate the above-mentioned composite sheet on the surface side low melting point polyethylene 07C03A was used.

The cup-type paper container was passed through a tunnel-type oven furnace that was heat-treated at 120 ° C. for 80 seconds to foam the surface low-melting-point polyethylene to form a heat-insulating layer, thereby producing a barrier-type heat-insulating paper container.
Table 3 shows the results of measurement of the molding defect rate in the process of molding the heat insulating paper container, the oxygen permeability and organic matter permeability after the heat insulating paper container was created, and the crystallization degree of the EVOH resin immediately after the composite sheet processing and after the heat insulating paper container was made. It is shown in 2.

As shown in Table 2, in Examples 1 to 5 of the present invention, the molding defect rate was low, and the paper container had good moldability.
In addition, the oxygen barrier performance is maintained even before the foaming process, but the crystallinity of the barrier layer is advanced by the heat treatment in the foaming process, and the oxygen permeability is lowered, thereby expressing a better oxygen barrier property. I understand. The organic matter permeability is also a low value, and it has good organic matter barrier performance.

On the other hand, in Comparative Example 1, the container moldability was good, but since the barrier layer was not laminated, both the oxygen barrier performance and the organic matter barrier performance were greatly inferior.
In Comparative Example 2, the oxygen barrier performance and organic barrier performance were better than Comparative Example 1, but the molding defect rate was high, and there were many molding defects in the skive process and the paper container molding process.

  In Comparative Example 3, the oxygen barrier performance and the organic matter barrier performance were still better than Comparative Example 2, but similarly, the molding defect rate was high, and there were many molding defects in the skive process and the paper container molding process.

In Comparative Example 4, the oxygen barrier performance and the organic matter barrier performance were good, but since the progress of crystallization of the barrier layer in the composite sheet processing process was rapid, molding defects were likely to occur in the skive process and the paper container molding process. It was.
Also, if the processing temperature at the co-extrusion laminating process is not increased at the composite sheet processing stage, sufficient adhesion to the base paper cannot be obtained, and at the processing temperature of 330 ° C., the EVOH layer used for the barrier layer at the time of processing is thermally deteriorated. Film breakage due to objects occurred.

In Comparative Example 5, the container moldability and barrier property evaluation results were the same as in Comparative Example 4.
As described above, in the barrier-insulated paper container of the present invention, the permeation of flavor components contained in the contents to the outside of the container, the oxidation deterioration of the contents due to oxygen intrusion from the outside of the container, and further the outside of the container It is effective in suppressing the transfer of odor components from the contents to the contents.
In addition, the barrier heat insulating container can be provided by reducing process defects in the process of molding the composite sheet used in the paper container to the paper container molding process.

DESCRIPTION OF SYMBOLS 1 Heat insulation layer 2 Base paper 3 High melting point polyethylene layer 4 Barrier layer 5 Sealant layer

Claims (2)

The body member forming the side wall portion of the paper container was laminated in the order of heat insulating layer (1) / base paper (2) / high melting point polyethylene layer (3) / barrier layer (4) / sealant layer (5) from the outside of the container. It is a composite sheet, wherein the heat insulating layer (1) is made of a polyethylene resin having a lower melting point than the high melting point polyethylene layer (3), and is formed by foaming the heat insulating layer with heat after molding a paper container. In a paper container,
The composite sheet constituting the body member is formed by laminating a resin layer including at least a barrier layer (4) on the high melting point polyethylene layer (3) previously laminated on the base paper (2) by an extrusion laminating method. Oh it is,
The extrusion temperature at the time of extrusion lamination of the barrier layer (4) is 230 ° C. to 280 ° C., the cooling water incoming temperature of the cooling roll is 15 ° C. to 25 ° C., the take-up speed is 80 m / min or more,
In the foaming step for forming the heat insulating layer (1), heat treatment is performed at 110 ° C. to 130 ° C. for 1 minute or more,
The crystallinity of the barrier layer (4) immediately after extrusion laminating the resin layer containing the barrier layer (4) is 20% to 35%,
By forming the heat insulation layer (1) by foaming with heat after the container is formed, the barrier layer (4) has a crystallinity of 35% to 70%. barrier insulation paper container barrier property after step is characterized that you increase.   The barrier heat insulating paper container according to claim 1, wherein the barrier resin used in the barrier layer (4) is a saponified ethylene-vinyl acetate copolymer.

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