JPS60110658A - Easy open molding vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an easy-open molded container, and more particularly, it has an excellent combination of sealing reliability and easy-open properties due to beer-off (peel-off). This effectively eliminates the feathering that occurs when the lid is peeled off and opened! Concerning easy-open molded containers.

Conventionally, the container body is made of a thermoplastic plastic such as polypropylene, and the lid body has a heat sealant layer on the base material. Packaging bodies that are sealed by heat sealing are widely used in fields such as food packaging.

(7) The heat sealant layer can not only be heat-sealed to the propylene surface to form a heat-sealed structure with excellent sealing reliability, but also the formed sealing structure can be easily opened by hand. It must have enough strength to be peelable.

For this purpose, the heat sealant layer is made of polypropylene as a base and is blended with a resin or rubber that does not exhibit fusion properties to the polypropylene, or if it does exhibit it, the degree of fusion is low. However, in such blends, polypropylene is blended with different resin components that are difficult to mix with each other, resulting in a non-uniformly dispersed structure.When the lid is peeled off, feathering occurs at the peeled part. There is a problem in that it causes fuzzing or stringiness, which is commonly called ``fuzziness'', which results in poor appearance of the peeled and opened part. This feathering is thought to be caused by the resin having the above-mentioned dispersed structure becoming fibrous due to the tension at the time of peeling.

Recently, Japanese Unexamined Patent Application Publication No. 1672/1983 uses a blend containing a crystalline propylene resin and polyethylene in a weight ratio of 50:50 to 95:5 as a heat sealant, and furthermore, a heat sealant is used as a heat sealant. It has been disclosed that the occurrence of phasing can be prevented by using a cover material in which this blend is bonded via a modified propylene resin layer modified with an acid or an acid anhydride.

The present invention relates to improvements in the above-mentioned technology, and in particular, in this type of easy-open molded container, when the container is opened by peeling, it effectively prevents the heat sealant layer from peeling off from the base material and prevents facer 11ing. It is also an object of the present invention to provide a means to further strengthen the adhesion between each layer of the lid material.

According to the present invention, the cup-shaped container body has at least the inner surface made of propylene-based resin and has a flange at the open end, and a lid body that is heat-sealed to the flange portion of the container body, and the lid body includes: It consists of a laminate of a base material, a heat sealant layer made of a blend of crystalline propylene resin and polyethylene, and a propylene resin layer interposed between them, and has a downward tension along the cup-shaped side wall of the container body. Provided is an easy-open molded container characterized in that it has a protrusion and a heat sealing surface is formed on the outside of the protrusion.

The invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1 showing an easy-open molded container of the present invention, this container consists of a container body 1 and a lid 2. As shown in FIG. The container body 1 has at least an inner surface made of propylene-based resin, and is composed of a cup-shaped side wall 3 and a bottom 4. At the outside of the open end of the side wall B,
It has a flange portion 5 that is integral with this.

On the other hand, as shown in the cross-sectional view of FIG. 2, the lid body 2 consists of a base material 6 and a heat sealant layer 8 bonded to the base material via an adhesive layer 7. As shown in FIG.
, a projecting portion 9 is provided along the side wall portion B of the container body,
An important feature is that a heat seal portion 1o is provided on the outside of this overhang portion 9, and furthermore, a tab 11 for picking is provided on the outside of the seal portion 10. This projecting part 9Fi has a tapered annular shape, and its lower end is connected to a downwardly recessed top plate part 12, and the lid body 2 has a shape of a drop lid as a whole. According to the publication, by providing the downward projecting portion 9 adjacent to the lid seal portion 1o, the heat sealant m8 can be peeled off! Significant advantages in terms of prevention and anti-phasing can be achieved.

Blends of crystalline propylene resin and polyethylene are certainly suitable for the purpose of forming a heat seal that has a reliable seal and is easy to peel off by hand for a container body made of propylene. However, when the lid is peeled off (-), the sealing part is completely destroyed (and even afterwards, it has the disadvantage that it is still easy to cause stringing (phasing) of the blend layer itself from the sealing part). .

The degree of occurrence of this phasing is determined by the blend layer 80.
It also depends on the degree of adhesion to the substrate 6 and the thickness of the blend layer 8.

According to the present invention, by providing the downward projecting portion 9 adjacent to the sealing portion 1o of the lid 2, cohesive failure may occur within the blend layer 8 itself when the lid 2 is peeled off. However, due to the edge effect of the overhanging portion 9, the peeling is completed without peeling off the sealant layer or causing stringiness of the blend from the sealed portion. In addition, in the present invention, the resin layer of the overhang part 9 is stretched and oriented by the overhang molding of the lid 2, and the adhesion of the blend layer 80 to the base material 6 is improved due to the wedge effect due to this molecular orientation. 7.
This is thought to be another important factor in preventing ethering.

In the present invention, as the propylene resin in the blend, in addition to crystalline (tactical) polypropylene, a crystalline propylene 1/7-ethylene copolymer may also be used. Low-density, medium-density, or high-density polyethylene can be used as the ethylene material.
In particular, if polyethylene with a density of 0.94 ff/cr1 or more is used, it is effective even for retort sterilization. Blend ratio (weight ratio) of propylene resin and polyethylene fl-150:5[) to 95:5, especially 55:
It is best to be in the range of 45 to 80:20, and
Melt index (AST, MD-1238,2
/10 minutes] of 4 to 70, especially 15 to 50, and a melt index of 2 to 50.
In particular, it is preferable to use polyethylene of 6 to 15.

The blend that is the heat sealant of the present invention may contain a sixth resin component to improve its compatibility. Examples of such a third resin component include ethylene-vinyl acetate copolymer, ethylene-acrylic 1)-1) copolymer, crystalline ethylene-propylene copolymer, crystalline ethylene-propylene-butene-1 Copolymers, ethylene-propylene rubber, ethylene-propylene-nonconjugated diene rubber, and ionically crosslinked olefin copolymers (ionomers) may be used alone or in combination of two or more.

As the propylene resin for the adhesive layer 7, it is advantageous to use a common propylene resin for extrusion coating, especially one with a melt index of 4 to 70 t/10 minutes, because it improves the adhesive strength in stretch molding. is 15 to 50 f
/10 min propylene-based resin is used.

On the other hand, when a backbone polymer such as crystalline polypropylene or crystalline propylene-ethylene copolymer is graft-modified with an ethylenically unsaturated carboxylic acid or its acid anhydride, it is economically possible to use a common propylene resin. Not only is this disadvantageous compared to the case of using a lid material, but also the adhesive force between each layer of the lid material becomes weaker.

As the base material 6, a thick polypropylene sheet, a laminate of polypropylene and other resin films, metal foils, etc. are used. Preferred examples of laminates include polypropylene 7'-propylene/propylene vinyl alcohol copolymer/polypropylene laminate, polypropylene sheet coated with polyvinyl 11 denene chloride, and polypropylene/aluminum foil/polypropylene laminate.

The thickness of these substrates 6 is preferably in the range, for example, from 100 to 800 microns, in particular from 150 to 50 microns, while the thickness of the adhesive layer 7 is preferably in the range from 5 to 50 microns, in particular from 10 to 30 microns. It is good to have
The thickness of blend N8 is between 5 and 60 microns, especially 10
In manufacturing the lid body 2, the propylene-based 11W adhesive layer 7 and the blend heat sealant layer 8 are co-extruded through a multi-layer die, and this co-extrusion is -
Extrusion coat 7 so that the base material 6 and adhesive layer 7 are adjacent to each other.
First, a laminate provided with a heat sealant layer is prepared. Next, this laminate is subjected to molding such as press molding, vacuum molding, pressure molding, etc. 1-7 to form the overhang portion 9. Overhang part 9
The suitable height is between 1 and 30W, particularly between 5 and 20W.

Various molded containers are used in which the inner surface is made of propylene and the heat-sealed portion is made of polypropylene. Of course, this container may be a blow molded container or an injection molded container made of polypropylene alone, or a draw molded container by pressure forming, plug assist molding, vacuum forming, etc. from a film, sheet, etc. Similar containers may be formed from laminates with other plastics, paper, metal foils, etc.

The heat-sealing operation can be performed using heat-sealing means known per se, such as heat-sealing bars, high-frequency induction heating, and the like.

The container according to the present invention is not only capable of forming a heat-sealed part that is easy to heat-seal, has excellent sealing reliability, and is resistant to heat sterilization, but also can be easily opened by peeling, and the peeled part can be easily sealed. ) It has the excellent advantage that the package can be opened without leaving any rubbing residue.

The invention is illustrated by the following example.

Example Polypropylene was injection molded to form a cup-shaped container body having a flange at the opening and having a diameter of 75 mm.

Next, 250μ polypropylene (melting point 165C1 melt index = MI 20 ii' / 10m1n)
sheet with melting point of 154C1 density of 0.90 g/
ctLJf I Ka25 y / 1 [1 mm, ethylene-propylene copolymer layer with ethylene content of 5 molar, melting point of 154 C, density of 0.90 f / C1d
Polypropyref 6 with SM I of 252/10+++in
0 weight ratio and melting point 1'IOC, density 0.92 Y
/crl, M I is 122/10m1R, coextrusion i-coating of 40wt% polyethylene triblend to form 250μ polypropylene layer/15μ adhesive layer/
A laminated sheet of 15μ heat sealant layers was formed. This laminated sheet was vacuum-formed to form a tab-attached lid having a protruding portion and a heat-sealed portion and having a diameter of 75 φ.

The cup-shaped container body is filled with coffee jelly, and the sealing lid is placed on the opening flange at a temperature of 0OC2 and a pressure of 3K.
Thermal bonding was carried out under the sealing conditions of f/al- and a time of 1 second.

When the lid was opened from the tab portion of the seal lid to remove the lid from the container body, it was easy to unseal, and no feathering or peeling from the laminated interface was observed on the peeled surface of the flange portion. Separately measuring the seal strength of the seal lid, we found that
It was 1210 liI/1.5 crn.

Comparative Example The material layer configurations of the container body and lid were the same as in the examples, but the shape of the lid was not a drop lid but a punched lid. The contents were filled into the container body, and the lid was heat-sealed under the same sealing conditions as in the example.

When the lid was opened from the container body, the lid peeled off from the laminated interface, and unsealing could not be achieved satisfactorily.

[Brief explanation of the drawing]

FIG. 1 shows a cross-section of an easy-open molded container of the present invention consisting of a container body and a lid, and FIG. 2 shows a cross-sectional view of the lid. 1... Container body, 2... Lid body, 5...
...Flange part, 9...Protrusion part, 10...
...Heat seal part, 11...Tab. Patent applicant Toyo Seikan Co., Ltd. Figure 1

Claims (1)

[Claims] (1) Consists of a cup-shaped container body whose at least the inner surface is made of propylene-based resin and has a flange at the open end, and a lid body heat-sealed to the flange portion of the container body, and the lid body is connected to the base material. , consisting of a laminate of a heat sealant layer made of a blend of crystalline propylene resin and polyethylene, and a propylene resin layer interposed between them, and having a downward protrusion along the cup-shaped side wall of the container body. An easy-open molded container comprising: a heat-sealing surface formed on the outside of the projecting portion.