JPS59199462A - Easy open type heat-seal cover - 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-to-open heat-sealable plastic lid, and more particularly to a plastic heat-sealable lid that has excellent transparency, storage stability, easy-opening properties, and sealing performance. It is something.

In addition to regular heat-sealed lids, peelable lids, easy-to-open heat-sealed lids made by injection molding, etc. are conventionally known as heat-sealed lids that require transparency.
These lids still have disadvantages in terms of storage stability, ease of opening, and sealing reliability compared to the easy open end lids used for canning. For example, a peelable seal lid is a plastic film with a layer of heat sealant.The heat sealant is made by blending wax, tackifier, elastomer, etc. with olefin resin such as polyethylene to improve the seal strength. I
The one adjusted to the order of Kf/15 run is used. This type of peel-a-pull seal lid lacks sealing reliability when the package filled with contents is heat sterilized, and the Ministry of Health and Welfare Notification No. 17 (enacted on August 1, 1978)
Even in Japan, food containers that are heat-sealed and sterilized by pressure heating are heated to 2.3 K? / It is required to have a heat seal strength of 15M or more.

On the other hand, with ordinary heat-sealed lids that are sealed with such high seal strength, it is extremely difficult to peel them off by hand at the heat-sealed interface, and currently the lids are opened using tools such as knives and scraps. .

In addition, a heat-seal lid has already been proposed in which the ribs that define the part of the lid that should be opened and the opening tab are integrally molded by plastic injection molding, but such injection-molded lids have poor heat-sealability. In connection with the fact that it is made of certain polyethylene, etc., gas permeation through the panel occurs on a non-negligible order, and there are still problems in terms of long-term shelf life of the contents, and the panel is not easy to tear. There are still problems in terms of ease of opening.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a plastic heat-sealable lid that overcomes the above-mentioned drawbacks and has an excellent combination of transparency, preservability, ease of opening, and sealing performance.

Another object of the present invention is to provide a novel structure comprising a plastic panel having a laminated structure, a weakening line carved into the panel, and an opening tab provided at a portion to be opened that is defined by the weakening line. We offer plastic heat seal lids.

According to the present invention, in the easy-to-open heat-sealable lid that forms a heat-sealed portion with the container body to seal the container body, the lid has at least a heat-nol property at least on the inner peripheral portion, and is substantially heat-sealable. It consists of a glass panel with a gas barrier resin layer on the entire surface, and the line of weakness that defines the part to be opened reaches halfway in the thickness direction of the plastic panel closer to the center than the peripheral part to be heat-sealed. There is provided an easily openable heat-sealed lid characterized in that a plastic opening tab is integrally fixed to the portion of the plastic panel to be opened.

The invention will be explained in detail below based on specific examples shown in the accompanying drawings.

In FIG. 1 showing the easy-open heat seal lid of the present invention applied to a container, FIG. 2 showing the lid disassembled, and FIG. 6 showing an enlarged cross-section of the main part of the lid, this lid is A plastic panel 1 with a laminated structure described in detail below; a score 8 provided on the plastic panel 1 to partition a portion 7 to be opened; and an opening seal provided integrally with this portion 7 to be opened. It is an important feature to have tabs 9 for use.

In this embodiment, the plastic panel 1 comprises a heat-sealable thermoplastic resin inner surface material 2, a moisture-resistant thermoplastic resin outer surface material 4, and a gas barrier resin layer 6 sandwiched therebetween.

This panel 1 has a peripheral part 5 for heat sealing via a circumferential rim part 6, and as described above, a score 8 is provided on the center side of the peripheral part 5 to define the part to be opened. There is.

The container 10 to which this heat-sealing lid is applied is, for example,
As shown in FIG. 1, it is formed from a laminate of an inner surface material 20 of heat-sealable thermoplastic resin, an outer surface material 21 of moisture-resistant thermoplastic resin, and a gas barrier resin layer 22 sandwiched between them. , a side wall portion 12 integrally connected to the side wall portion 12 and a 7-run portion 16 connected to this opening end, and a sealing is performed between the 7-run portion 16 and the lid peripheral portion 5 by heat sealing.

In the present invention, as shown in the enlarged view of FIG. 6, the score 8 is provided so as to reach from the outside of the panel 1 to the middle of the thickness of the panel 1, and the score 8 is provided at the center side of the score 8 and at the beginning of opening of the score. A hole 15 passing through the panel 1 is provided adjacent to the section 14. The opening tab 9 consists of an opening ring 16 and a bed 17.
Has a tearing tip 18 on one end? have. Rivet 1
7, it is made of a thermoplastic resin that can be heat-sealed to the inner surface material 2 of the panel 1, and the rivet 17 is inserted into the through hole 15 of the panel 10 and protrudes from the inner surface side of the lid material, as shown in the drawing. The tab 9 is fixed to the lid member by spreading the tip 19 in the horizontal direction. The tip portion 19 of the rivet 17 protruding toward the inner surface side and the inner surface material 2 of the lid member are sealed and engaged by heat fusion.

As shown in FIG. 6, one end of the unsealing tab 9 and the tearing tip 18 are provided in a substantially mold-like positional relationship with the unsealing start part 14 of the score of the lid material 1. In the specific example shown in FIGS. 1 to 6, the unsealing ring 16 and the rivet 17 are both integrally formed of heat-sealable resin.

In the present invention, by constructing the plastic panel 1 as a laminate of the heat-sealing resin inner material 2 and the gas barrier resin layer 6, the plastic panel 1 can be easily attached to the lid of the container while maintaining the transparency that is a characteristic of plastic. It provides the heat-sealing properties necessary for sealing the contents and the gas barrier properties necessary for long-term storage of the contents.

In a preferred embodiment of the present invention, as shown in FIG. 6, the score 8 is carved so that the gas barrier resin layer 6 is substantially continuous even at the score 8 position of the plastic panel 1. , an even more excellent gas barrier effect can be obtained.

In the present invention, from the standpoint of ease of opening, it is important to carve a score of 8 on this laminated plastic panel 16, that is, in the field of lids (d), by providing a score of 8, this part can be broken. Although it is known to make the gas barrier resin layer filter easier, in the present invention, the gas barrier resin layer filter
By providing the score 8 on the plastic panel, the ease with which the score 8 can be opened due to breakage is improved. That is, in the case of plastic panels made solely of heat-sealable resin such as polyethylene, even if scores are provided on the panels, it is often difficult to shear the panels at the score positions. . This is because heat-sealable resins such as polyethylene generally have a low tensile modulus (ASTMD-668), and the resin stretches too much even at the above-mentioned score position, making it difficult to absorb the shearing force. On the other hand, for example, gas compounds such as ethylene-vinyl alcohol copolymer (1
All glossy resins contain polar groups such as hydroxyl groups, nitrile groups, ester groups, amide groups, and halogen atoms in their polymer chains, and strong hydrogen bonds are formed between these molecular chains. Therefore, it exhibits a higher tensile modulus than the polyethylene and the like. Thus, the gas barrier
When a score of 8 is placed on the plastic panel 1 provided with the plastic resin layer 6 and a shearing force is applied to this score 8, the shearing starting point is fixed due to the presence of the score 8 and the suppression of elongation of this resin layer B. This makes the opening operation extremely smooth and easy.

Next, in order to tear open the plastic panel 1, it is a problem to make a cut in the opening start part 14 of the score 8 mentioned above, and once the score 8 is made, the score 8 starts from this cut. Fracture of the laminate progresses relatively easily along the . In order to make a cut in the score 8 when opening, a sharp and large shearing force is required, and a strong fulcrum is required for this purpose. In the present invention, the opening tab 9 provides this strong fulcrum and facilitates the formation of the score 8 opening initiation portion 14.

More specifically, in the specific example shown in FIGS. 1 to 6, a through hole 15 is provided close to the opening start part 14,
Opening tab on 5? The ring 16 of the tab 9 is inserted into the rivet 17, and the tip 18 of the rivet is widened and fixed by heat fusion, thereby forming a strong fulcrum against opening.
When the tab 9 is lifted upward, the tip of the tab 9 is pushed into the opening start part 14 of the score, making it easy to form a cut by shearing the score. That is, the widened part 1 of the rivet tip
8 serves to prevent the portion that should serve as a fulcrum from being excessively deformed even when the lid member 1 is made of a flexible and relatively soft material.

In the heat seal lid of the present invention, the cross-sectional area of the through hole 15, that is, the cross-sectional area of the rivet 17 is S.

When the seal area between the rivet tip 19 and the inner surface material 2 is 51, the area ratio of sQ:sl is 20=1.
It is clever to set the ratio so that the ratio is between 1:20 and 1:20, especially between 5:1 and 1:10.

In other words, if the area ratio of the heat-sealed part is smaller than the above range, there is a tendency for poor sealing, displacement or removal of the opening tab, etc., while on the other hand, if the area ratio of the heat-sealed part is larger than the above range. In this case, it becomes difficult to effectively push the tearing tip 8 into the opening starting portion 14 of the score, and the ease of opening tends to be impaired. According to a preferred embodiment of the present invention, by selecting the area ratio of the heat-sealed portion within the above-described range, a combination of sealing reliability, tab adhesion, and ease of opening can be obtained.

In this aspect of the invention, the through hole 15 provided in the lid material 1
The cross-sectional area is such that the opening tab can be effectively fixed, and it is generally desirable to have a cross-sectional area in the range of 2 to 100-1, particularly 4 to 0-1.

In the present invention, from the viewpoint of gas barrier properties, 37r
and oxygen permeability coefficient CPO2 measured under the conditions of 0% RH
) is 2 x 10” CC・cm/crri・sec
・Smaller than cmllg, especially lXlQu head・on
/ ad-, smaller than H9, and tensile modulus (ASTMD-668) of 12,000 Kg/- or more,
In particular, any high gas barrier resin having a gas barrier property of 15,000 Ky,/ctr1 or more is preferably used. High gas bar 11
The most preferred example of the yarn resin is an ethylene-vinyl alcohol copolymer (saponified ethylene-vinyl acetate copolymer), especially one containing vinyl alcohol with a density of 20 to 8.
It is preferable that the ethylene content is in the range of 0 molar ratio, particularly 50 to 75 molar ratio, in other words, 25 to 50 molar ratio, and that the degree of saponification is 96φ or more, especially 99 or higher.

Other examples of high gas barrier resins include, in order of importance:
Examples include vinylidene chloride resin, nylons, IJ resin, and vinyl chloride resin. These resins can be used in the form of a polymer blend of two or more types if desired. The oxygen barrier resin layer 6 should have a thickness of at least a certain value in terms of gas barrier properties and tear resistance. It is preferable from the point of view that the thickness is generally 5 microns or more, particularly 10 microns or more, but from the economic point of view it is desirable to have a thickness of 50 microns or less.

The heat-sealable inner material 2 may be any heat-sealable olefin resin, such as low-1 medium- or high-sealable olefin resin.
Density polyethylene, tactical polypropylene, crystalline propylene-ethylene copolymer, ethylene-butene-1 copolymer, ethylene-butene-1 copolymer, ethylene-vinyl acetate copolymer, etc. are used. The thickness of the inner layer may generally be in the range 10 to 100 microns, particularly 20 to 60 microns.

As the outer material 4, the same type of resin as the inner material 2 is used for the purpose of protecting the barrier resin, and also biaxially oriented polypropylene film, biaxially oriented polyester film, etc. are used. The thickness of the outer material should generally be in the range 10 to 600 microns, particularly 50 to 200 microns.

Lamination adhesion between the inner surface material 2 or the outer surface material 4 and the gas resin layer 6 can be performed using acid-modified olefin resins such as maleic anhydride-modified polyethylene or maleic anhydride-modified polypropylene, urethane-based or epoxy-based adhesives, etc. Generally speaking, the overall thickness of the plastic panel can be made using
02 to 30 Rooster, especially 0.5 to 2. The depth of the score provided on the flannel is preferably within the range of 1/2 to 6/4 of the overall thickness of the panel, especially from the viewpoint of ease of opening and impact resistance of the score. It is desirable that it be within the range of 1/2 to 2/2.

The lid panel is formed by means known per se, for example, the aforementioned laminated sheet is sheared to a predetermined size, and the sheared panel is formed into the desired lid shape by means such as drawing, stretch forming, or press forming. This is done by molding into a shape and then engraving a score. During the above-mentioned molding and score engraving, the plastic panel to be processed is heated to the softening temperature of the constituent resin, which is generally selected from a temperature range of 50 to 200 C depending on the type of resin. Chikaradama is desirable. The force exerted by pressing the score die against the heated panel; =h Even when the oxygen barrier resin mentioned above is engaged with the tip of the score die, it tends not to break but rather to spread thinly. shows,
It is recognized that gas barrier properties are maintained even in the score area.

This is done by molding a heat-sealable resin onto the opening tab 9il-1' and the inner surface material 2 by means such as injection molding, and heat deformation of the tip of the rivet 17 and fusion with the inner surface material are extremely This can be easily done by pressing under heating using sonic irradiation, radiant heat, thermal conduction, etc., or by press molding.

Many modifications can be made to the container lid of the present invention as long as the spirit described above is satisfied. For example, the opening ring 16
4 and 5 instead of providing a tearing tip at one end.
As shown, the expanded tip portion 19 of the rivet 17
The edge 26 of a is the unsealing start part 14 with a score of 8α. By providing the ring 16 in a positional relationship overlapping with Z and lifting the ring 16 upward, a cut may be formed by shearing the score at the opening start part 14α.

Further, the shape of the score 8 is not limited to a raindrop shape or a small circular shape, but can be a so-called full open shape in which the entire inside of the seal portion is opened, as shown in FIGS. 6 and 7. In the specific example shown in FIGS. 6 and 7, the score is 8h.
is provided so as to reach halfway in the thickness direction from the inner surface of the panel.

The lid of the present invention is useful as a lid that requires transparency and long-term preservation of contents, and is particularly useful for plastic cups formed by vacuum forming, uniaxially or biaxially stretched plastic cups formed by plug assist forming, pressure forming, etc. In addition to the completely transparent packaging, it can also be used in combination with opaque containers such as metal cans, plastic containers, metal foil containers, etc.
It can also be used to seal various containers such as metal foil/plastic composite containers, paper/plastic composite containers, and paper/metal foil/plastic composite containers.

The invention is illustrated by the following example.

Example 1 Using the materials shown in Table 1, a 5-layer coextrusion lamination method was performed to create a 2-layer structure consisting of ethylene-propylene random copolymer layer (thickness 600 μm)/maleic anhydride modified polypropylene layer (J110 μrn)/ethylene. A laminated sheet of -vinyl alcohol copolymer layer (thickness 20 μm)/maleic anhydride modified polypropylene layer (thickness 10 μm)/ethylene-propylene random copolymer layer (200 μm) was obtained.

Next, a circular plate was punched out from this laminated sheet.

This circular plate was heated to 1400℃ and was press-molded to remove I.
- Molded into a lid shape, and then subjected to liquid po-type scoring using a score die, and punching small holes with diameters as shown in Table 1 in the panel part to create a hole as shown in Figure 2.
7 A lid intermediate body having a lid-shaped diameter of 60rrrynφ was created.

Next, an opening tab in which an opening ring and a rivet were integrated as shown in FIG. 2 was manufactured by injection molding using the materials shown in Table 1.

The rivet part of this opening tab is inserted into the small hole in the center of the lid intermediate body, and the head of the rivet is shaped as shown in 19 in Figures 1 to 6 by the method shown in Table 1, and the inner surface is It was welded to the resin layer.

Next, a multilayer sheet of polypropylene/maleic anhydride-modified polyglopylene/ethylene-vinyl alcohol copolymer/maleic anhydride-modified polypropylene/polypropylene was molded, with an inner diameter of 52 mm and a height of 162 cm.
A cup with a flange width and thickness of 3 m+++ and 1.8 mm as shown in Figure 1 was hot filled with orange juice, and the lid was heat-sealed to the opening flange of the container body.

When the container filled with the contents was opened from the ring tab at the opening of the lid, the opening could be carried out smoothly along the predetermined score line. The condition of the opening after opening was good, with no defects such as feathering.

Example 2 Using the materials shown in Table 1, a 5-layer laminated sheet of 6 types was created by a 5-layer coextrusion lamination method, and the resulting laminate sheet was cold-rolled to make it highly transparent. A laminated sheet of density polyethylene (250i1 m) / maleic anhydride-modified low-density polyethylene (1' 0 μm) / ethylene-vinyl alcohol copolymer (20 μm) / maleic anhydride-modified low-density polyethylene (10 μm) / medium-density polyethylene was obtained. Ta.

Next, a lid similar to that in Example 1 was created using this laminated sheet.

Orange juice was poured into a cup having the same shape as in Example 1, which was formed from a multilayer sheet of medium density polyethylene/maleic anhydride modified low density polyethylene/ethylene-vinyl alcohol copolymer/maleic anhydride modified polyethylene/medium density polyethylene. After hot filling, the lid was heat-sealed to the opening flange of the container body.

When the container filled with the contents was opened from the ring tab at the opening of the lid, the opening could be carried out smoothly along the predetermined score line, and no defects such as feathering occurred.

Examples 6 and 4 The construction was made by dry lamination using the materials shown in Table 2. For Example B, polyacrylonitrile (1
50 μm) / urethane adhesive (4 μm) / polypropylene <70 μm), and for Example 4, polyethylene terephthalate (200 μm) / urethane adhesive (4 μm)
A laminated sheet of TL)/polypropylene (70 μm) was obtained.

Circular plates were then punched out from these laminated sheets. Both of these circular plates are heated to 260C and formed into a drop lid shape by press molding, and then scored into a liquid po type using a score die, and a small hole having a diameter as shown in Table 2 is punched in the center. A lid intermediate body having a diameter of 60 mm φ as shown in Fig. 4 was created.

Next, an opening tab in which an opening ring and a rivet were integrated as shown in FIG. 4 was manufactured by injection molding using the materials shown in Table 1.

The rivet part of this opening tab is inserted into the small hole in the center of the lid intermediate body, and the head of the rivet is shaped as shown in 19α in Figures 4 and 5 by the method shown in Table 2, and the inner surface is It was welded to the resin layer.

Next, hot filling the cup used in Example 1 with sake,
The lid was heat-sealed to the opening flange of the container body.

When the container filled with the contents was opened using the ring tab at the opening of the lid, the opening could be carried out smoothly along the predetermined score line, and no defects such as feathering occurred.

Example 5: Using the materials shown in Table 2, the composition was formed by extrusion sandwich lamination using hard vinyl chloride (200 μm)/urethane anchor layer/low density polyethylene (30 μm).
)/ethylene-vinyl acetate copolymer (40μ771) laminate sheet was obtained.

Next, a circular plate was punched out from this laminated sheet.

This circular plate was heated to 100C and formed into a drop lid shape with a groove with a semicircular cross section on the outer periphery using a vacuum forming method.Furthermore, a score die was used to perform a fully open score process from the inner resin layer side, and the panel was made. A lid intermediate body having a diameter of 150 mmφ was prepared by punching a small hole having a diameter as shown in Table 2 in the portion.

Next, this intermediate lid was inserted into an injection mold, and medium density polyethylene was injection molded to form an opening tab as shown in FIG. 6-7, which was welded to the inner resin layer.

In addition, a can body blank is printed on one side of the tin plate and coated with a finishing varnish mainly composed of styrenated epoxy ester, and then the outer diameter is 148 mm using a welding uneven composition forming machine.
X-Kanno-Ito manufactured a 50-piece biased assembly, and one open end of the resulting biased assembly was provided with an inward curl portion, and the other open end was provided with a flange portion. Furthermore, a tin lid was double wrapped around this flange.

The thus obtained can body was filled with pie, and the lid was heat-sealed to the curled portion of the can body using a high-frequency sealer.

When the can filled with the contents was opened from the ring tab at the opening of the lid, the opening could be carried out smoothly along the predetermined score line, and no defects such as feathering occurred.

Comparative Example 1゜Tensile modulus of Example 5: 28,000 Kq/cr
! Instead of hard vinyl chloride, it has a tensile modulus of 1,200 to 9/crtt, a melting point of 109 U, and a density of 0.921 f.
//a:,.

Ml 1. When low density polyethylene of Of/1 []TfuA was used, feathering occurred during opening and smooth opening could not be achieved.

In addition, after storing the cans filled with pies for 6 weeks, they were opened and the pie flavors of Example 5 and Comparative Example 1 were compared. In Example 1, the flavor was mainly due to oxidation of oil and fat.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a container that is a specific example of the present invention, FIG. 2 is an exploded perspective view of the lid shown in FIG. 1, and FIG. 6 is an exploded perspective view of the lid shown in FIG. FIG. 4 is an exploded perspective view of the lid according to another embodiment of the present invention; FIG. 5 is an enlarged sectional view of the tab attachment portion of the lid; FIG. FIG. 6 is a plan view of a lid body according to still another specific example of the present invention; FIG. 7 is an enlarged sectional view of a tab attachment portion of the lid body in FIG. The reference number 1 is the lid body, 2 is the resin inner material, 6 is the gas barrier resin layer, 4 is the thermoplastic resin outer material, 8 is the score, and 9
1 is an opening tab, 10 is a container body, 16 is a flange part, 1
4 is the opening start part of the score, 15 is a small hole, 16 is an opening ring, 17 is a rivet, 18 is a tip for tearing, 19 is a tip protruding from the inside of the rivet, 20 is an inner surface material of the container body, 21 Reference numeral 22 indicates a thermoplastic resin outer surface material of the container body, and 22 indicates a gas barrier resin layer 22 of the container body. Patent applicant Akira Kishimoto Figure 1 Figure 2 915 Figure 4 Figure 5 190 Figure 6 Figure 7 Figure 8b 2

Claims (2)

[Claims] (1) In an easy-to-open heat-sealable lid that forms a heat-sealed portion with the container body to seal the container body, the lid is heat-sealable at least on the inner peripheral portion and is provided with a gas barrier over substantially the entire surface. - The lid is made of a plastic panel with a thermoplastic resin layer, and the weakened line that defines the part to be opened is provided on the center side of the lid, rather than the peripheral part to be heat-sealed, so as to reach halfway in the thickness direction of the plastic panel. An easy-to-open heat-sealable lid, characterized in that a plastic opening tab is integrally fixed to a portion of the plastic panel that is to be opened. (2) The heat seal lid according to claim 1, wherein the gas barrier resin layer is substantially continuous even at the weakened line position of the plastic panel.