JP6028385B2 - Lid and packaging - Google Patents

Description

  The present invention relates to a lid member and a package.

  In the food packaging field, packaging forms in which cup-shaped containers such as instant noodles, jelly, and yogurt are filled with contents are increasing. Recently, trays that can be refrigerated and have heat resistance such as microwave ovens are gradually increasing.

  As typical examples of these containers, thermoplastic resins such as polyethylene, polystyrene, expanded polystyrene, polypropylene resin, and polyester resin are generally manufactured using a manufacturing method such as injection molding or vacuum compression molding.

  In recent years, paper cups have been developed in which polyolefin resin such as polyethylene resin is laminated on paper in consideration of resource saving, volume reduction of waste, and recyclability. Not only, but also dairy products such as beverages and yogurt have been filled.

  In general, these containers are provided with a lid material in consideration of contents protection and easy opening at the time of opening. In addition, the sealant layer of these lid materials is required to have a high sealing property with respect to the container of the adherend in order to protect the contents, and to have a function of having an easy opening property when opened.

  As one of such containers and lid materials, a paper container coated with a polyethylene resin on the surface, and a lid material that can be suitably used as an easily openable lid material on this paper container, from a base material layer and a heat seal layer And an easily openable paper container using a composite film in which the heat seal layer is composed of a blend resin of 70 to 95% by weight of low density polyethylene (including linear low density polyethylene) and 30 to 5% by weight of polybutene-1. (Patent Document 1).

  In addition, as a heat-seal layer using a resin blended with linear low-density polyethylene and polybutene-1, a package for boil treatment of deep-drawn packaging used for each heat-seal layer of a bottom material and a lid material (Patent Document 2).

  Furthermore, a package of deep-drawing gas pack packaging using a resin blended with linear low-density polyethylene and polybutene-1 for the heat seal layer of the lid, using low density polyethylene for the heat seal layer of the bottom material. (Patent Document 3).

  Known documents are shown below.

Japanese Patent Laid-Open No. 10-337829 Japanese Patent Laid-Open No. 10-24517 Japanese Patent Laid-Open No. 11-227125

However, for the heat seal layer of the lid material used for the lid material for polypropylene containers,
There is no appropriate one, and hot melt has been conventionally used. Hot melt does not have a strong sealing strength, and there is a concern about the sealing performance unless it is thickly coated, and there is a problem in terms of cost.

  The present invention has been made in view of the above circumstances, and provides a lid and a packaging body in which a heat seal layer can be surely sealed in a polypropylene container, has excellent easy-opening properties, and does not cause a stringing phenomenon at the time of opening. The challenge is to do.

The invention according to claim 1 of the present invention is a lid for a container made of polypropylene, comprising a base material layer and a heat seal layer, and the heat seal layer has a low density of 30% by weight of linear low density polyethylene. Either a resin in which 50% by weight of polyethylene and 20% by weight of polybutene-1 are mixed, or 20% by weight of linear low density polyethylene, 60% by weight of low density polyethylene, and 20% by weight of polybutene-1 It is a lid material characterized by being formed by a mixed resin layer blended so as to become.

The invention according to claim 2 of the present invention is the lid according to claim 1, wherein the density of the linear low-density polyethylene is 0.910 Kg / m ³ or less.

  The invention according to claim 3 of the present invention is a package characterized in that the lid material according to claim 1 or 2 is sealed in a form in which a respective heat seal layer is opposed to a polypropylene container. .

  In the lid material and package of the present invention, the heat seal layer in the lid material can be reliably sealed against a polypropylene container, has excellent easy-openability, and does not cause a stringing phenomenon when opened.

It is explanatory drawing which showed the example of the package of this invention typically on the front.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is an explanatory view schematically showing an example of the package of the present invention on the front side.

  The package 100 of this example first comprises a container 20 and a lid 10 as shown in FIG. The container 20 of this example is a single layer molded container made of polypropylene, and a flange portion 21 is provided. The lid member 10 includes a base material layer 11, an adhesive layer 12, and a heat seal layer 13. And it is sealed by heat-sealing to the flange part 21 of the container 20 with the heat-seal layer 13 of the lid 10.

  Paper or a synthetic resin film is used for the base material layer 11 of the lid 10. Moreover, it is good also as the base material layer 11 which consists of multiple layers, such as a multilayer synthetic resin film and a laminated body of paper and a synthetic resin film. At least one layer of the base material layer 11 is made of paper, polyethylene terephthalate (PET), stretched polypropylene (OPP), or stretched nylon (ONy) so that the cover material 10 does not stretch when the lid material 10 is peeled from the container 20. It is preferable to use a stretched film of synthetic resin.

  The heat seal layer 13 is made of a mixed resin in which 20 to 30% by weight of linear low density polyethylene, 50 to 60% by weight of density polyethylene, and 20% by weight of polybutene-1 are blended.

Linear low-density polyethylene has a property of adhering to polypropylene.
The density of the linear low density polyethylene is 0.94 or less.
A low-density linear low-density polyethylene having a low density of not more than Kg / m ³ is considered to be particularly strong and can be used as a heat seal material having an easy-open property (easy peel property).

  However, in general linear low density polyethylene with just adjusted density, it may adhere strongly to polypropylene depending on the conditions, and a large force may be required at the time of opening. Is not necessarily satisfied.

  For example, if it seals at 180 degreeC, it will become the heat seal intensity | strength of 15N / 15mm width, and easy openability will not be obtained. Therefore, polybutene-1 is added to linear low density polyethylene to adjust the heat seal strength.

  However, even when polybutene-1 is added, a stringing phenomenon (a phenomenon in which each resin destroyed at the time of opening opens into a string shape) occurs at the time of opening. When this stringing occurs, not only the peeled surface is not clean, but also a thread-like heat seal material by stringing may be mixed in the container.

  In order to solve this, a part of the linear low density polyethylene is replaced with low density polyethylene and mixed with polybutene-1, so that the strength of the polyethylene itself, such as tensile breaking strength, is weakened so that stringing does not occur. Can be. That is, it is solved by forming a sea-island structure in which islands of polybutene-1 are scattered in a polyethylene sea where linear low-density polyethylene and low-density polyethylene are compatible.

  Therefore, as described above, the heat seal layer 13 is a mixture in which 20 to 30% by weight of linear low density polyethylene, 50 to 60% by weight of density polyethylene, and 20% by weight of polybutene-1 are blended. A resin layer is used. There may be a blending error of about 10% in the blending ratio of polybutene-1.

  By using such a heat seal layer 13 as a container lid, when the heat seal layer is heat sealed to a polypropylene container, the heat seal layer 13 can be reliably sealed, has excellent easy-opening properties, and does not cause stringing when opened. .

  The adhesive layer 12 is a layer for adhering the base material layer 11 and the heat seal layer 13, and in the case of this example in which the heat seal layer 13 is extruded and laminated, the adhesive layer 12 also extrudes the thermoplastic resin. A film is formed and extrusion laminated to the base material layer 11 by coextrusion.

  When the heat seal layer 13 is a film formed in advance, the adhesive layer 12 may be similarly extruded by a thermoplastic resin and laminated by sandwich lamination. Alternatively, the adhesive layer 12 may be laminated by dry lamination using an adhesive.

  The container 20 of this example is a single-layer molded container made of polypropylene, but in the present invention, the container 20 is not limited to this, and is a multilayer molded container in which polypropylene is laminated as a heat seal layer. Also good. Moreover, the container by which the polypropylene was laminated | stacked as a heat seal layer with a paper container like a paper cup may be sufficient. That is, any form may be used as long as the heat seal layer is made of polypropylene.

  Further, it is not necessary to provide a clear heat-sealing portion like the flange portion 21. For example, a top curl portion whose upper end is curled outwardly like a paper cup is provided, and an upper edge of the top curl portion is provided. The heat seal layer 13 of the lid member 10 may be opposed to the heat seal layer exposed to the heat seal layer and heat sealed.

  Specific examples of the present invention will be described below.

<Example 1>
As a mixed resin of the heat seal layer, a linear low density polyethylene having a density of 0.908 is 30% by weight, a low density polyethylene having a density of 0.918 is 50% by weight, and polybutene-1 is 20% by weight. A mixed resin was prepared.

  Using a coextrusion laminating apparatus on the stretched polyethylene terephthalate film 12 μm of the base material layer 11, the mixed resin of the low-density polyethylene and the heat seal layer 12 of the adhesive layer 12 is extruded at a thickness of 25 μm and 10 μm, respectively. A three-layer laminated film of density polyethylene and mixed resin was prepared, and the lid material of Example 1 was prepared.

<Example 2>
The mixed resin for the heat seal layer is 20% by weight of linear low density polyethylene having a density of 0.908, 60% by weight of low density polyethylene having a density of 0.918, and 20% by weight of polybutene-1. A lid material of Example 2 was prepared in the same manner as in Example 1 except that a resin mixed with was prepared and a heat seal layer was provided.

  Below, the comparative example of this invention is demonstrated.

<Comparative Example 1>
As a resin for the heat seal layer, a resin prepared by mixing 80% by weight of linear low density polyethylene having a density of 0.908 and 20% by weight of polybutene-1 without adding low density polyethylene is prepared. A cover material of Comparative Example 2 was prepared in the same manner as in Example 1 except that a seal layer was provided.

<Comparative example 2>
As the resin for the heat seal layer, a linear low density polyethylene having a density of 0.908 is 60% by weight, a low density polyethylene having a density of 0.918 is 20% by weight, and polybutene-1 is 20% by weight. A lid material of Comparative Example 2 was prepared in the same manner as in Example 1 except that a mixed resin was prepared and a heat seal layer was provided.

<Comparative Example 3>
As a resin for the heat seal layer, a linear low density polyethylene having a density of 0.908 is 20% by weight, a low density polyethylene having a density of 0.918 is 50% by weight, and polybutene-1 is 30% by weight. A lid material of Comparative Example 3 was prepared in the same manner as in Example 1 except that a mixed resin was prepared and a heat seal layer was provided.

<Comparative example 4>
The resin for the heat seal layer is 30% by weight of linear low density polyethylene having a density of 0.908, 40% by weight of low density polyethylene having a density of 0.918, and 30% by weight of polybutene-1. A lid material of Comparative Example 4 was prepared in the same manner as in Example 1 except that a mixed resin was prepared and a heat seal layer was provided.

<Test method>
The lid materials of the example and the comparative example were tested by the following method and evaluated for comparison.

Instead of the container 20, a single-layer sheet of polypropylene was prepared, and the lid materials of the example and the comparative example were heat-sealed at a pressure of 0.2 MPa for 1 second at respective temperatures.

  The seal piece was measured for heat seal strength according to JIS-Z0238. Moreover, the peeling interface state was observed. The results are summarized in Table 1.

以下に、実施例と比較例との比較結果について説明する。

Below, the comparison result of an Example and a comparative example is demonstrated.

<Comparison result>
The lid materials of Examples 1 and 2 are low in heat seal strength by blending a large amount of low density polyethylene, and the heat seal strength does not change greatly depending on the heat seal temperature, and a wide temperature range. Easy opening is obtained. In addition, the resin did not get stringed when it was peeled off and was good.

  The lid material of Comparative Example 1 to which no low-density polyethylene is added and the lid material of Comparative Example 2 with a low blending ratio of low-density polyethylene have high heat seal strength and are difficult to open.

  Further, in the lid materials of Comparative Examples 3 and 4 in which the blending ratio of polybutene-1 was increased, the peeling interface appeared in two ways, cohesive peeling and interface peeling, and the peeling interface was unstable. In this case, stringing was likely to occur. It is considered a thing. If stringing occurs, the appearance will be poor, and the resin in the heat-seal layer that has become thread-like may enter the container, resulting in an accident involving foreign matter.

  Furthermore, if the peeling interface is unstable, it becomes difficult to manage the sealing performance and determine the sealing performance. If the peeling interface is either cohesive peeling or interfacial peeling, the seal sealing property can be confirmed, but if both cohesive peeling or interface peeling occurs, it is difficult to check the seal sealing property.

  As described above, the lid material of the present invention can be sealed by reliably sealing the heat seal surface to the polypropylene container. Moreover, it is easy to open and does not cause a stringing phenomenon at the time of opening.

DESCRIPTION OF SYMBOLS 100 ... Packaging 10 ... Cover material 11 ... Base material layer 12 ... Adhesive layer 13 ... Heat seal layer 20 ... Container 21 ... Flange part

Claims (3)

A container for a polypropylene container comprising a base material layer and a heat seal layer, the heat seal layer comprising 30% by weight of linear low density polyethylene, 50% by weight of low density polyethylene, and 20 of polybutene-1. Formed by mixed resin layer containing 20% by weight of linear low density polyethylene, 60% by weight of low density polyethylene and 20% by weight of polybutene-1 A lid material characterized by being made. The lid material according to claim 1, wherein the density of the linear low-density polyethylene is 0.910 Kg / m ³ or less.   A packaging body, wherein the lid material according to claim 1 or 2 is sealed in a form made of a polypropylene container with the respective heat seal layers facing each other.

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