JP6468933B2 - Lid material - Google Patents

Description

  The present invention relates to a lid for sealing and sealing an opening of a container body, and relates to a lid used for a cup container such as a snack packaging container or a dry food container, and particularly the surface of the flange part of the cup container. However, it is related with the cover material for sealing the opening part of the container coat | covered with polyethylene.

  Compared to the lid material used for conventional cup noodle containers, snack packaging containers or dried food containers have a high air-tightness and prevent opening during transportation. There is a demand for a lid material having a high strength, for example, a lid material having an opening strength of 20 N or more.

  As a lid material used for such a container, for example, a paper layer / adhesive layer / aluminum foil / optional adhesive layer / sealant layer shown in Patent Document 1 are laminated in this order, and a linear chain is used as the adhesive layer. A cover material using a low-density polyethylene (LLDPE) is known.

  When sealing the cup container with this lid member, heat sealing is usually performed by applying a heat source from the paper layer side. At that time, in order to obtain a high sealing strength between the container and the lid member, it is necessary to increase the temperature of the heat source applied from the paper layer side (for example, 170 ° C. to 180 ° C.). However, when heat sealing is performed at a high temperature, the water contained in the paper is vaporized by the heat applied during the heat sealing and becomes water vapor, which is removed between the paper layer and the aluminum foil. At this time, since the water vapor barrier property of the aluminum foil is high, the water vapor loses a place to escape and a peeling phenomenon occurs between the paper layer and the adhesive layer, thereby causing a problem that blisters are generated. It was.

  By this, when picking up the pulling bull tab on the outer periphery of the lid material and pulling it up, when peeling the lid material from the container, it is not peeled cleanly at the sealant layer part, and it is torn between the paper layer and the adhesive layer, There was a problem that a part of the lid material remained in the container, and normal opening could not be performed.

  For example, as shown in Patent Document 1, by laminating an adhesive layer between an aluminum foil and a sealant layer, the tear resistance (tear resistance) is improved and the lid material itself is improved in tearing. In this case, there is a problem that a so-called "string drawing phenomenon" occurs in which the adhesive layer remains in a fibrous state on the seal peeling surface at the time of opening, and normal opening may not be possible. It was happening.

JP 2004-142780 A

  The present invention solves the problems of the prior art, and even if the lid material has a high sealing strength between the container and the lid material, for example, a lid material having an opening strength of 20 N or more, a blister, and Provided is a lid material that can suppress the occurrence of a stringing phenomenon, does not cause tearing in the lid material itself, and has good openability.

  The above problems can be solved by the following present invention.

[1] A lid for sealing and sealing the opening of the container body,
The lid member has a paper layer as an outermost layer, an aluminum foil as an intermediate layer, and a sealant layer as an innermost layer,
The sealant layer includes a polyethylene-based resin as a main component, and the paper layer and the aluminum foil are bonded via an ethylene-methacrylic acid copolymer resin, and the aluminum foil and the sealant layer Are bonded via linear ultra-low density polyethylene,
A lid for sealing and sealing the opening of the container body.
[2] The lid material according to [1], wherein the linear ultra-low density polyethylene layer and the sealant layer are layers formed by a single laminate method, respectively.
[3] The lid material according to [1] or [2], wherein the polyethylene-based resin is low-density polyethylene.
[4] The lid material according to any one of [1] to [3], wherein the ethylene-methacrylic acid copolymer resin has an acid component content of 5% by mass or more.
[5] The lid according to any one of [1] to [4], which is a lid for a snack packaging container or a dry food container.
[6] A content comprising the lid material according to [5], a container hermetically sealed with the lid material, and a content contained in the container, wherein the content is a snack or a dried food Container with goods.
[7] The container according to [6], wherein an opening strength between the lid member and the container is 20 N or more.
[8] A step of obtaining a first laminate by laminating a paper layer and an aluminum foil via an ethylene-methacrylic acid copolymer resin;
Forming a linear ultra-low density polyethylene layer on the aluminum foil side of the first laminate to obtain a second laminate; and the linear ultra-low density of the second laminate. Forming a sealant layer containing a polyethylene-based resin as a main component on the polyethylene layer side to obtain a third laminate,
The manufacturing method of a cover material containing this.
[9] The method for manufacturing a lid according to [8], wherein the linear ultra-low density polyethylene layer and the sealant layer are each formed by a single laminate method.

  According to the present invention, it is possible to suppress the occurrence of blistering and stringing phenomenon even in the case of a lid material having a high sealing strength between the container and the lid material, for example, a lid material having an opening strength of 20 N or more. It is possible to provide a lid member that does not break in itself and has good openability.

It is sectional drawing which shows the laminated structure of the cover material of this invention.

  The present invention is configured by laminating a paper layer, an ethylene-methacrylic acid copolymer resin layer, an aluminum foil, a linear ultra-low density polyethylene layer, and a sealant layer in this order. The present invention relates to a lid that is heat-sealed with a container opening.

  Hereinafter, the lid of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the laminated structure of the lid material of the present invention. As shown in FIG. 1, the lid 1 has a paper layer 11 as an outermost layer, an aluminum foil 13 as an intermediate layer, and a sealant layer 15 as an innermost layer. It is a lid 1 in which an ethylene-methacrylic acid copolymer resin 12 is laminated therebetween and a linear ultra-low density polyethylene 14 is laminated between an aluminum foil 13 and a sealant layer 15.

(Paper layer)
The paper layer 11 is a layer that serves as a base material for the lid, and preferably has rigidity, excellent mechanical strength such as tensile strength and tear strength, and interlayer strength, and also excellent printability. Specific examples of the constituent material of the paper layer 11 include coated paper and high-quality paper. Particularly preferred is single-sided coated paper, which improves printability by using the coated surface as a printing surface and makes the uncoated surface a laminated surface with a resin layer, thereby preventing a decrease in laminate strength due to the coating agent.

  In the lid of the present invention, the paper layer 11 may further be provided with a protective layer 16 made of a resin film such as PET (polyethylene terephthalate) on the outer surface side of the paper layer 11 as shown in FIG. . Here, the protective layer 16 is provided to protect the outer surface side of the paper layer 11 and improve the appearance of the lid material itself.

The closure member of the present invention, the thickness of the paper layer 11 is preferably an in the basis weight of ^{64g / m 2 ~110g / m 2} .

(Aluminum foil)
Moreover, the aluminum foil 13 which comprises the said cover material (1) of this invention has light-shielding property and gas-barrier property for protecting the contents (for example, dried food etc.). This aluminum foil may have a thickness of 6 to 9 μm, for example.

(Sealant layer)
The sealant layer 15 includes a polyethylene resin as a main component. A preferred embodiment of the sealant layer 15 is formed by blending a specific amount of a polyethylene resin, a crystalline polypropylene resin, and a low molecular weight polyethylene wax. In a more preferred embodiment, the polyethylene resin is 40 to 87 wt%, crystalline. The polypropylene resin is 10 to 40 wt%, and the low molecular weight polyethylene wax is 3 to 20 wt%. Among these blending amounts, the blending amount of the low molecular weight polyethylene wax is particularly preferably 5 to 15 wt%.

  The polyethylene resin is not particularly limited as long as it is a polyethylene resin such as low-density polyethylene, linear low-density polyethylene, and high-density polyethylene, and among them, low-density polyethylene is preferable from the viewpoint of extrusion lamination processability. In particular, low density polyethylene produced by a high pressure method is preferred. Further, the melt mass flow rate measured under a temperature condition of 190 ° C. in accordance with JIS K6922-1 of a polyethylene resin is not particularly limited, but among them, 10 to 50 g / 10 minutes is preferable.

  The crystalline propylene resin is not particularly limited as long as it is a crystalline polymer composed of homopolymer of propylene or a copolymer of propylene and ethylene, and among them, a random copolymer of propylene and ethylene is preferable. Further, the melt mass flow rate measured under a temperature condition of 230 ° C. in accordance with JIS K7210 of a crystalline polypropylene resin is not particularly limited, but it is preferably 1 to 30 g / 10 minutes, and particularly preferably 0. It is preferable that it is 5-10 g / 10min.

  The low molecular weight polyethylene wax is a polyethylene wax having a number average molecular weight of 1,000 to 10,000 according to the GPC method. This low molecular weight polyethylene wax thermally decomposes a polymerization type obtained by polymerization of ethylene and polyethylene having a high molecular weight. Either of the decomposition types obtained by doing can be used.

(Ethylene-methacrylic acid copolymer resin layer)
The ethylene-methacrylic acid copolymer resin layer 12 is a layer provided between the paper layer 11 and the aluminum foil 13. The ethylene-methacrylic acid copolymer resin is a resin obtained by copolymerizing a methyl methacrylate monomer with an ethylene monomer, and since it contains a polar group in the molecular chain, in addition to toughness and flexibility, glass, metal It has adhesiveness to etc. The ethylene-methacrylic acid copolymer resin layer 12 may have a thickness of 10 to 30 μm, for example.

  In the present invention, by bonding the paper layer 11 and the aluminum foil 13 with the ethylene-methacrylic acid copolymer resin layer 12, it is possible to increase the adhesive strength between them and suppress the generation of blisters. Specifically, without being bound by theory, even when the moisture contained in the paper expands due to the effect of heat applied when sealing the lid to the container, it is firmly bonded Since peeling does not occur at the interface between the paper layer 11 and the ethylene methacrylic acid copolymer resin layer 12 and at the interface between the ethylene methacrylic acid copolymer resin layer 12 and the aluminum foil 13 that are firmly bonded, the blister phenomenon occurs. It can be suppressed.

  The acid component content of the ethylene-methacrylic acid copolymer resin layer 12 is preferably 5% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, or 10% by mass or more, and 20% by mass. Hereinafter, 18 mass% or less, 15 mass% or less, or 12 mass% or less is preferable.

  If the acid component content of the ethylene methacrylic acid copolymer resin layer 12 is too low, the adhesion to the aluminum foil 13 is weakened, so that the adhesive strength required for the lid material cannot be obtained. On the other hand, when the acid component content of the ethylene methacrylic acid copolymer resin layer 12 is a certain level or more, the adhesion to the paper layer 11 and the adhesion to the aluminum foil 13 become strong, and thus the adhesive strength required for the lid material. Can be obtained.

  In the present specification, the “acid component” refers to a structural unit derived from methyl methacrylate in an ethylene-methacrylic acid copolymer (EMAA).

(Linear ultra-low density polyethylene layer)
The linear ultra-low density polyethylene layer 14 is a layer provided between the aluminum foil 13 and the sealant layer 15. The linear ultra-low density polyethylene is a linear low-density polyethylene having a density region of 0.91 g / cm ³ or less, and has flexibility, transparency, and low-temperature sealing properties.

  The linear ultra-low density polyethylene layer 14 may have a thickness of 20 to 40 μm, for example. In the case of this application, it may be either a Ziegler-Natta catalyst or a single site catalyst. If the thickness of this layer is less than 20 μm, the tear resistance (breaking resistance) is insufficient, and if it exceeds 40 μm, extrusion is difficult and the material cost increases, which is not preferable.

  In the present invention, by bonding the aluminum foil 13 and the sealant layer 15 with the linear ultra-low density polyethylene layer 14 (VLLDPE), the adhesive strength between the aluminum foil 13 and the sealant layer 15 is increased, and the stringing phenomenon at the time of opening the lid is suppressed. can do.

  Specifically, without being bound by theory, the density of linear low density polyethylene (LLDPE) has an influence on the adhesive strength with the aluminum foil 13, and the lower the density, the more self-adhesive. It is considered that the adhesive strength to the aluminum foil is high. That is, it is considered that the linear ultra-low density polyethylene layer 14 (VLLDPE) can maintain high adhesive strength with the aluminum foil 13.

  Furthermore, since the sealant layer 15 is mainly composed of a polyethylene resin that is the same resin as the linear ultra-low density polyethylene layer 14, the linear ultra-low density polyethylene layer 14 has a high adhesive strength with the sealant layer 15. Can be maintained. Therefore, since peeling between the linear ultra-low density polyethylene layer 14 and the sealant layer 15 is suppressed, an unexpected stringing phenomenon can be suppressed, and the sealant layer 15 can be opened as designed. It is considered to be.

(Manufacturing method of lid material)
The lid can be produced by a method comprising the following steps:
A step of laminating a paper layer and an aluminum foil via an ethylene-methacrylic acid copolymer resin to obtain a first laminate;
Forming a linear ultra-low density polyethylene layer on the aluminum foil side of the first laminate to obtain a second laminate; and the linear ultra-low density of the second laminate. Forming a sealant layer containing a polyethylene-based resin as a main component on the polyethylene layer side to obtain a third laminate;

  The process of obtaining a 1st laminated body can be performed by sand lamination, dry lamination, etc., for example.

  The step of obtaining the second laminate and the step of obtaining the third laminate can be performed, for example, by single lamination, coextrusion or the like. In general, “single laminate” refers to extrusion lamination of one kind of resin composition on a certain base material. On the other hand, “coextrusion” means that two kinds of resin compositions are simultaneously extruded and laminated on a certain substrate.

  Since the step of obtaining the second laminate and the step of obtaining the third laminate can generally be carried out with an apparatus simpler than coextrusion, it is preferably carried out by single lamination. In that case, in the step of obtaining the second laminate, the line speed in the flow direction (MD direction) is 100 m / min, the screw rotation speed is 70 rpm to 80 rpm, and the extrusion temperature under the die is 290 to 310 ° C. It is preferable that Moreover, in the process of obtaining a 3rd laminated body, line speed (MD direction) is 110 m / min, screw rotation speed is 70 rpm-80 rpm, and the extrusion temperature under die | dye is 300-330 degreeC. preferable.

  If desired, the method for manufacturing a lid member may include a punching step of punching the obtained third laminate body into a predetermined shape after the step of obtaining the third laminate body to obtain a lid member.

  The punching process is performed, for example, by cutting the third laminated body into a sheet form with a rotary cutter, forming a plurality of sheets with a cutting machine, and then individually punching the sheets into the shape of a lid with a punching device. Can be.

Next, an Example demonstrates this invention concretely.
[Example 1]
The following materials were prepared:
Paper: Daio Paper Co., Ltd. (model number: Ryuo Coat 79.5 g / m ² or 65 g / m ² )
Ethylene-methacrylic acid copolymer resin containing 11% by mass of acid component: Mitsui DuPont Polychemical Co., Ltd. (model number: Nucrel N1108C)
Aluminum foil: manufactured by Toyo Aluminum Chiba Co., Ltd. (model number: 1N30)
Linear ultra-low density polyethylene: Tosoh Corporation (model number: Nipolon HM300K)
Sealant layer: Tosoh Corporation (model number: Mersen A2111G2)
Container: Aluminum high barrier cup with inner diameter φ81mm and flange width 2.5mm

<Creation of cover material>
Using a laminator, a laminate a was prepared by using an ethylene-methacrylic acid copolymer resin as a sand laminate between the paper layer and the aluminum foil at a temperature below the die of 285 ° C. to 305 ° C.

  Using an extruded single laminator, linear ultra low density polyethylene was extruded and laminated (single laminate) on the aluminum foil side of the laminate a to prepare a laminate b.

  Using the extruded single laminator, the resin composition for the sealant layer was extruded and laminated (single laminate) on the linear ultra-low density polyethylene layer side of the laminate b to prepare a laminate c.

  The obtained laminate c was cut into a sheet with a rotary cutter, and was cut into sheets with a cutter. Then, the sheet | seat was pierced in the shape of a cover material with the individual punching apparatus, and the cover material was obtained.

  The obtained cover material had a configuration of “paper layer / ethylene-methacrylic acid copolymer (EMAA) resin layer / aluminum foil / linear ultra-low density polyethylene (VLLDPE) adhesive layer / sealant layer”. .

<Creation of container with lid>
Cover the sealant layer side of the lid with the container opening, and press a ring seal with a width of 10 mm heated to 150 ° C. at a pressure of 75 kg / Cap for 0.7 seconds to obtain a container with a lid It was.

[Example 2]
Instead of ethylene-methacrylic acid copolymer (EMAA) resin (model number: Nucrel N1108C, manufactured by Mitsui DuPont Polychemical Co., Ltd.) containing 11% by mass of acid component, ethylene containing 4% by mass of acid component A lid was obtained in the same manner as in Example 1 except that a methacrylic acid copolymer resin (model number: Nucrel AN4228C, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used. Thereafter, a lidded container was obtained in the same manner as in Example 1.

[Comparative Example 1]
Other than using low-density polyethylene (LDPE) (model number: Suntec L1850K, manufactured by Asahi Kasei Chemicals Corporation) instead of ethylene-methacrylic acid copolymer resin (model number: Nucrel N1108C, manufactured by Mitsui DuPont Polychemical Co., Ltd.) Obtained a cover material in the same manner as in Example 1. Thereafter, a lidded container was obtained in the same manner as in Example 1.

[Comparative Example 2]
Instead of linear ultra low density polyethylene (VLLDPE) (model number: Nipolon HM300K, manufactured by Tosoh Corporation), ethylene-methacrylic acid copolymer resin containing 11% by mass of acid component (model number: Nucrel N1108C, Mitsui DuPont) A lid was obtained in the same manner as in Example 1 except that Polychemical Co., Ltd. was used. Thereafter, a lidded container was obtained in the same manner as in Example 1.

[Comparative Example 3]
Example 1 is used except that low-density polyethylene (model number: Suntech L1850K, manufactured by Asahi Kasei Chemicals Corporation) is used instead of linear ultra-low-density polyethylene (model number: Nipolon HM300K, manufactured by Tosoh Corporation). A lid was obtained. Thereafter, a lidded container was obtained in the same manner as in Example 1.

(Evaluation 1: Opening test of lid with container with lid)
About the container with a lid material obtained by Examples 1 and 2 and Comparative Example 1, an opening test was performed by picking up and pulling the bull tab for opening the lid material and peeling the lid material from the container. Here, ten samples were prepared for each example, and an opening test was performed ten times. The case where tearing did not occur at the time of opening with all 10 pieces was marked as ◎, and the case where tearing occurred at the time of opening 1 to 4 pieces out of 10 was marked as ○, and tearing occurred at the time of opening 5 to 10 pieces out of 10 pieces. The case was marked with x. The test results are shown in Table 1.

  As can be seen from the results in Table 1, the paper layer and the aluminum foil layer were made of an ethylene-methacrylic acid copolymer resin as compared with Comparative Example 1 in which the paper layer and the aluminum foil were bonded via low-density polyethylene. In Examples 1 and 2, which are bonded together, good openability was shown by suppressing the generation of blisters. Further, by increasing the acid component content of the ethylene-methacrylic acid copolymer resin as in Example 1, compared with Example 2 in which the content of the acid component is relatively low, ethylene-methacrylic acid copolymer Adhesive strength between the coalesced resin layer and the aluminum foil was increased, and good openability was exhibited.

(Evaluation 2: Measurement of opening strength)
About the container with a lid material obtained in Example 1 and Comparative Examples 2 and 3, using a trograph (model number: VE-10D) manufactured by Toyo Seiki Co., Ltd. The peel strength was measured by peeling 90 ° at a tension rate of 1 minute. The measurement results are shown in Table 2.

  As can be seen from the results in Table 2, the aluminum foil and the sealant layer were compared with Comparative Example 2 or 3 in which the aluminum foil and the sealant layer were bonded via an ethylene-methacrylic acid copolymer or low-density polyethylene. However, in Example 1 in which linear ultra-low density polyethylene was bonded, the adhesive strength between the aluminum foil and the sealant layer was increased, and a lid material having a high opening strength of 20 N or more was obtained. . Further, in Comparative Examples 2 and 3, the stringing phenomenon occurred by visual observation at the time of opening the lid material, whereas in Example 1, the stringing phenomenon at the time of opening the lid material did not occur, and good openability was achieved. Indicated.

DESCRIPTION OF SYMBOLS 1 Cover material 11 Paper layer 12 Ethylene-methacrylic acid copolymer resin layer 13 Aluminum foil 14 Linear ultra low density polyethylene layer 15 Sealant layer 16 Protective layer

Claims (9)

A lid for sealing and sealing the opening of the container body,
The lid member has a paper layer as an outermost layer, an aluminum foil as an intermediate layer, and a sealant layer as an innermost layer,
The sealant layer includes a polyethylene-based resin as a main component, and the paper layer and the aluminum foil are bonded via an ethylene-methacrylic acid copolymer resin, and the aluminum foil and the sealant layer Are bonded via linear ultra-low density polyethylene,
A lid for sealing and sealing the opening of the container body.   The lid according to claim 1, wherein the linear ultra-low density polyethylene layer and the sealant layer are layers formed by a single laminate method, respectively.   The lid according to claim 1 or 2, wherein the polyethylene-based resin is low-density polyethylene.   The lid | cover material as described in any one of Claims 1-3 in which the said ethylene-methacrylic acid copolymer resin has an acid component content rate of 5 mass% or more.   The lid | cover material as described in any one of Claims 1-4 which is a lid | cover material for the container for snack packaging, or the container for dry foods.   A container with contents, comprising the lid according to claim 5, a container sealed and sealed with the lid, and contents contained in the container, wherein the contents are snacks or dried food.   The container according to claim 6, wherein an opening strength between the lid member and the container is 20 N or more. A step of laminating a paper layer and an aluminum foil via an ethylene-methacrylic acid copolymer resin to obtain a first laminate;
Forming a linear ultra-low density polyethylene layer on the aluminum foil side of the first laminate to obtain a second laminate; and the linear ultra-low density of the second laminate. Forming a sealant layer containing a polyethylene-based resin as a main component on the polyethylene layer side to obtain a third laminate,
The manufacturing method of a cover material containing this.   The method for producing a lid material according to claim 8, wherein the linear ultra-low density polyethylene layer and the sealant layer are each formed by a single laminate method.

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