JPH0242606Y2 - - Google Patents

Description

[Detailed explanation of the idea]

(b) Purpose of the invention [Field of industrial application] This invention relates to container lids, and in particular to easy-to-open container lids that seal lids to molded containers for storing foods and other items by means such as heat sealing. [Prior Art] In recent years, cup containers and tray containers using at least a portion of plastic material have been used as containers for sealed storage of foods and other articles. Such containers are widely used because they are lightweight, have the same shelf life as cans and bottles, are low cost, meet the requirements for resource conservation, and are easy to handle. One of the most important requirements for ease of handling is the ease of opening the container lid. There is a great demand for such container lids that can be easily opened using only hands and fingers without the need for any other tools. Various types of easy-to-open container lids have been devised in the past, such as narrowing the seal width of the seal between the lid and the container to create a line seal, providing a protrusion on the seal of the cup, Efforts have been made to limit the sealing conditions (temperature, etc.) or to select a combination of materials for both sealing parts to make them peelable. [Problems to be solved by the invention] On the other hand, from the point of view of sealing performance, a more perfect one is desired, and there are problems in that it is difficult to achieve both sealing performance and ease of opening, and the structure is complicated. There was a problem that the number of steps increased and the cost became high. This invention was made in view of the above-mentioned circumstances, and aims to provide an easy-to-open container lid material that has both sealing properties and easy-to-open properties, has a simple structure, and is inexpensive. (b) Structure of the invention [Means for solving the problem] In response to this purpose, the easy-to-open container lid material of this invention is bonded to the opening of the container body on the innermost side, and is attached to the opening of the container body. A lid material for sealing, comprising an inner lining material, an intermediate material, and a base material laminated by co-extrusion molding in order from the innermost surface, the inner lining material being composed of a propylene homopolymer, and the intermediate material is composed of a mixed polymer of propylene mixed with an olefin other than propylene, and the base material is ethylene, propylene,
It is characterized by being composed of a random copolymer. The details of this invention will be explained below with reference to the drawings showing one embodiment. In FIG. 1, numeral 1 indicates an easily openable container lid material. The easy-open container lid material 1 is constructed by laminating a thin film inner adhesive material 2, an intermediate material 3, and a base material 4 by co-extrusion molding. The material combination of the thin film inner adhesive material 2, intermediate material 3, and base material 4 is such that the interlayer peeling force between the intermediate material 3 and the thin film inner adhesive material after being heat-treated at a temperature of 80°C or higher is the same as that of the intermediate material 3.
The delamination force is selected to be smaller than the interlayer peeling force between the base material 4 and the base material 4. As for how to select such materials, for example, propylene homopolymer is used as the thin film inner adhesive material 2, and propylene (homo-PP, homopolymer) is used as the intermediate material.
Mix olefin other than propylene with random PP or block PP at a mixing ratio of 5 to 50.
A mixed polymer of mol% was used, and the base material 4
An ethylene/propylene random copolymer with an ethylene content of 2 to 20 mol% is used as the
Both are coextruded with a melt index of 0.5 to 40. Examples of the olefin include LDPE (low density polyethylene), LLDPE (low pressure injected low density polyethylene), HDPE (high density polyethylene), PB-1 (polybutene-1), EPR (ethylene propylene rubber), isoprene, and polyethylene. 4-methylpentene-1 etc. can be used. The film thickness of the thin film inner adhesive material 2 is a film thickness that is easily torn at the inner edge part 7 of the heat sealing area of the opening flange 6 of the container body 5, for example, 5 μm, whereas the intermediate material 3 is 10 μm and the base material is 35 μm. The thickness shall be as follows. [Function] The easily openable container lid material 1 configured as described above is adhered to the opening flange 6 of the container body 5 by heat sealing to form a sealed container 11 and seal the contents. The sealed container 11 is then heat-treated at a temperature of 80° C. or higher. This heat treatment may be used for both retort processing, heating immediately before taking out the contents for eating and drinking, or for heating the easily openable container lid material 1. It may be a single heat treatment. In the sealed container 11 having the easy-open container lid 1 adhered to it, the internal pressure of the sealed container 11 acts to separate the easy-open container lid 1 from the opening flange 6 of the container body 5. However, the easy-open container lid material 1 and the opening flange 6 are heat-sealed, exhibiting the sealing performance as shown in the seal strength column of Table 1, and satisfying the standards regarding seal strength. Furthermore, against the action of this internal pressure, the coextruded layer of the easy-open container lid material 1 as a whole exerts a tensile resistance equivalent to the material strength, so the easy-open container lid material 1 does not break. On the other hand, when opening the sealed container 11 to take out the contents, the base material 4 and the intermediate material 3 of the layer constituent materials of the easily openable container lid material 1 are pulled up. It is easy to pick up only the base material 4 and the intermediate material 3 among the layer constituent materials of the easy-open container lid material 1. When the base material 4 and the intermediate material 3 are pulled up, the intermediate material 3 and the thin film inner adhesive material 2 are separated. This is because heat treatment such as retorting or boiling that is performed prior to opening reduces the adhesive strength between the thin film inner adhesive material 2 and the intermediate material 3, making it easier for the layers to peel off. Until it reaches the inner edge part 7 of the sealing area, the thin film inner adhesive material 2 is in a state of being bonded and reinforced to the opening flange 6, so the thin film inner adhesive material 2 will not be damaged, but delamination may occur at the inner edge edge part 7. When reaching the inner edge part 7, the thin film inner adhesive material 2 is no longer reinforced by the opening flange 6, so the thin film inner adhesive material 2 breaks along the inner edge part 7, and the sealed container 11 is removed from the opening. (Figure 3). [Experiment example] Laminate configuration 12μm PET/15μm Nylon/50μ
After filling the mPP cup container body (PP is homo PP, random PP, or block PP) with water, seal it by heat-sealing the lid material (any of A to E) shown in Table 2. , the seal strength was examined, and then the unsealability was examined by heat treatment (at 85°C to 120°C for 20 to 30 minutes), and the compatibility between sealability and unsealability was evaluated, and the results shown in Table 1 were obtained. Obtained.

【table】

[Table] (Evaluation 9) (a) Even with the same cup container body, the co-extruded layer structure of the lid material reduces the ease of opening (No. 2, 3, 4, 5), and cup containers with the same material combination. Even with the main body and lid, if (b) the flange angle θ is larger than 110°, the internal pressure seal will peel off in the direction 9 (Fig. 4), reducing the seal strength (Nos. 7 and 8). ), (c) If the heat treatment is not sufficient, the unsealability will be reduced (No. 11, 12), etc., so caution is required when using the lid material 1. (c) Effects of the invention As is clear from the above explanation, according to this invention, it is possible to obtain an easy-to-open container lid material that has both sealing performance and easy-opening property, has a simple structure, and is inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an easy-to-open container lid material according to an embodiment of the invention; FIG. 2 is an explanatory cross-sectional view showing a sealed container sealed with the easy-to-open container lid material shown in FIG. 1; FIG. 3 is a diagram showing the state of the sealed container shown in FIG. 2 just before opening, and FIG. 4 is an explanatory diagram showing the relationship between internal pressure and sealing performance in the sealed container with a large flange angle. 1...Easy-openable container lid material, 2...Thin film inner patch material, 3
...Intermediate material, 4...Base material, 5...Container body, 6...
...Opening flange, 7...Inner edge portion, 9...
Direction, 1... sealed container, 12... tab for picking.

Claims (1)

[Scope of utility model registration request] A lid material for sealing the container body by adhering to the opening of the container body on the innermost side, comprising an inner lining material, an intermediate material, and a base material laminated in order from the innermost side by coextrusion molding, The inner material is made of a propylene homopolymer, the intermediate material is made of a mixed polymer made by mixing propylene with an olefin other than propylene, and the base material is made of an ethylene-propylene random copolymer. Easy-to-open container lid material.