JPS59199444A - 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-sealed lid, and more particularly to an easy-to-open heat-sealed lid that has excellent tear-openability at the score section and corrosion resistance at the processed section. Regarding.

Conventionally, from a laminate of a metal foil base and a heat-sealable inner surface material, a portion of the laminate that should be opened inward from the periphery to be heat-sealed is opened in the middle of the thickness direction of the metal foil ( The present invention has already proposed a heat-seal lid that is partitioned by scores carved to reach this height and provided with an opening tab in the portion to be opened.

It goes without saying that the inner surface material of this heat-seal lid must be able to form a highly reliable sealing structure with the container body by heat sealing, but at the same time, when the lid is opened by shearing the score, It must be sheared sharply along and at the same time as the score. In this type of heat-sealing lid, a circumferential rim is formed between the heat-sealing periphery and the center panel on which the score is engraved by drawing or stretching the laminate in the thickness direction. It is common practice to form or stretch-mold a reinforcing lip or a recess to facilitate grasping of the opening tab.

When forming these, the inner material needs to plastically flow in response to the denaturation of the metal foil, but the heat-sealing resin that has excellent tearability at the score position described above can be There is a tendency for fine cracks to occur in the overhang molded part, and as the metal foil corrodes through these cracks, the gas barrier properties of the lid are reduced, and the metal in the contents leaks out. tends to occur.

Therefore, an object of the present invention is to provide an easy-to-open heat-sealed lid of the swa-openable type that eliminates the above-mentioned drawbacks.
There it is.

Another object of the present invention is to provide an easy-to-open heat-sealable lid made of a metal foil-heat-sealing material laminate that has excellent tear-opening properties at the score part and corrosion resistance at the drawn or stretch-formed part. It is on offer.

Still another object of the present invention is to provide a scored heat-seal lid that includes a plurality of olefin resin inner materials having a specific combination of tensile modulus.

According to the present invention, there is provided an easily openable heat-sealable lid for sealing the container body by forming a heat-sealing portion with the container body, the cough lid having a metal foil base and a heat-sealable inner surface material. The laminate is made of a laminate, and the laminate has a peripheral part to be heat-sealed, and a part inward from the peripheral part (this part is carved so as to reach the middle of the metal foil in the thickness direction). The inner material has a molded (slightly deformed) part in the thickness direction of the laminate, and the inner material has a
A combination of easy-openability and corrosion resistance characterized by having a laminated structure of an olefin resin layer with a high tensile modulus and another olefin resin layer with a relatively low tensile modulus on the metal foil side. Provides superior heat seal lids.

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

1, 2, 6, and 4, the heat-sealing lid 1 of the present invention has a peripheral portion 2 to be heat-sealed,
It consists of a center panel part 6 and an annular rim part 4 formed between the center panel part 6 and the center panel part 6 by drawing. This center panel part 6 (this is a score 6 that partitions the part 5 to be opened)
A rib 7 formed by stretch molding is provided in a portion of the center panel portion 6 outward from the score 6. The portion 5 to be opened is provided with an opening tab 8 integral therewith.

Is this heat seal lid 1 based on metal foil? and heat-sealable inner materials 10 and 11, which will be described in detail later.These heat-sealable inner materials 10 and 11 are bonded to the metal foil base 9 via, for example, an adhesive layer 12, and the metal foil base 9 A desired E-proof protective coating layer 16 is provided on the outer surface side. Figures 3 and 4 (0 as clearly shown)
The score 6 is provided so as to reach halfway in the thickness direction of the metal foil base 9.

The opening tab 8 has a ring-shaped grip portion 14 . In order to secure this tab 8 to the part 5 to be opened, in this example an opening 16 of small cross-sectional area is provided in said part 5 adjacent to the tear initiation part 15 of the score (Fig. 4). The opening tab 8 has a rivet portion 17;
This rivet portion 17 is inserted into the opening 16, and its tip 18 is expanded in the direction of the surface of the lid body (Z), and is thermally fused to the inner surface material 11 (hereinafter referred to as ζ) to fix the tab and secure the tab attachment portion. In this example, the rivet tip 18 of the opening tab is provided in substantially overlapping relationship with the tear initiation portion 15 of the score.

In FIG. 2, which shows the easy-open lid 1 of the present invention attached to a container body, the container body has a cylindrical body 1 with openings at both ends.
9 and a bottom 20 provided in sealing relation at one end thereof.

The body 19 is made of a flexible laminate material 9, and the laminate includes a paper substrate 21, a metal foil 22, and a heat-sealable inner surface 26, the paper substrate 21 and the metal foil 22 being They are pasted together with a heat-sealable resin 24, and a heat-sealable protective resin layer 25 is also provided on the outside of the paper substrate 21. There are seven flange 26 at the open end of the body part 19, and sealing is performed between the seven flange 26 and the lid peripheral part 2 by heat sealing, and at the same time, seaming is performed.

When opening the package, grasp the grip part 14 of the opening tab 8 with your fingers and lift it upward.The rivet part 17 will serve as a fulcrum, and the crushed tip 18 of the rivet will also be lifted upward. and this (accompanied by the tear start part 1 of the score)
5 (after this cut is made, the tab 8 is pulled #) I. The score 6 is then sheared and the container lid is opened.

An important feature of the present invention is that the heat-sealing inner material of the lid body has a relatively high elastic modulus (olefin resin layer 11 on the innermost side) and a relatively low tensile elastic modulus on the metal foil side. This is based on the fact that a laminated structure with the olefin resin layer 10 provides a desirable combination of tear-openability in the score section 6 and corrosion resistance in the processed sections 4 and 7.

As already mentioned, in this container lid, it is necessary that the laminate be torn accurately (and smoothly) at the score part 6, but it is necessary to use the most common heat sealant material such as low density polyethylene as the inner surface material. In contrast, the metal foil was torn at the score part, but the inner material was not torn, or even if it was torn, the tear occurred at a position different from the tearing position of the metal foil, and the opening operation This is thought to be because in the low-density polyethylene described above, the elongation of the resin at break is too large, and the tear position of this resin layer is not fixed at the shear position of the score.

On the other hand, when a layer of crystalline polypropylene is used as the inner material, the tearing position of this resin layer is fixed at the shearing position of the score, and the tearing of the inner material layer is also accurate (and smooth along the score). This is also done by the inventors ζ
Therefore, it has already been discovered that a laminate with an inner surface made of a highly tearable resin can be formed into a lid body with unevenness in the thickness direction by drawing or stretch molding. As a result, in the areas deformed by these moldings, the inner surface material became noticeably whitened, and in these whitened areas, numerous cracks were observed to have formed in the resin layer.These cracks naturally have the property of allowing liquid to penetrate. As a result, the metal foil serving as the base is corroded, and the gas barrier properties of the metal foil are lost.

In the present invention, by providing the olefin resin layer 10 having a small tensile p-elasticity modulus on the metal foil side, cracks that reach the metal foil base are prevented from forming even in the drawing part and the overhanging part G. is prevented, and moreover, the upper l of this resin layer 10
By providing the olefin resin layer 11 with a large tensile modulus, the tearing position of the inner surface material is the same as the shearing position of the metal foil (
It is fixed at the score position) and provides excellent opening performance.

As a heat-sealable olefin resin, low-1 medium-
Alternatively, high-density polyethylene, acid-modified polyethylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ionically crosslinked olefin copolymer (ionomer), polypropylene, random or block propylene-ethylene copolymer, A wide variety of olefin thread resins are known, such as acid-modified polypropylene, propylene-ethylene-butene-1 copolymer, or a blend of two or more of these. In the present invention ζ, the resin composition and crystallinity of the resin layers 10 and 11 are selected so as to satisfy the above-mentioned requirements.

Generally, ASTM D-668 for low modulus resin 110
When the tensile elastic modulus (kg/cm") of EL is EL, and the tensile elastic modulus of the high elastic modulus resin layer 11 is EH, EL=0.4 to 1
It is desirable to select and combine resins in the range of 0 x 10" EH = 6 to 20 x 10" EH-E, = o, s to 15 x 10".

Table 1 below shows the tensile modulus of various olefin thread resins listed in "Plastic Reader" published by Plastic Swage on May 10, 1978.

Table 1 Elastic modulus Low density polyethylene (LDPE) 1 to 6 medium
(MDPE) 2~
4 high CHDPE)
4-16 ionomer 1-4
Ethylene-vinyl acetate copolymer CEVA) 0.1-1 polypropylene (PP) 11-16 copolymer polypropylene 4-12 In the present invention, as shown in Table 1 above, the value of the tensile modulus is the above value. In addition to selecting the composition, crystallinity, etc. of the resin so that the desired tensile modulus is You can get a combination.

That is, when a reinforcing material or a filler is added to the resin ζ, the tensile modulus of the resin layer generally increases considerably. For example, when a filler such as Merck or the like is added to HDPE in an amount of about 4ON, its tensile modulus is found to be improved by 2 to 4 times Qjl.

Thus, the present invention (in this case, an unblended olefin thread resin is used as the low elastic modulus resin layer 10, and an olefin thread resin containing a reinforcing material or a filler is used as the blade high elastic modulus resin layer 11). The desired combination of elastic moduli can be obtained by (rubbing).

In the present invention, it is particularly advantageous that the low elastic modulus resin Jvi1o and the high elastic modulus resin layer 11 have heat bonding properties to each other.
Of course, it can be used if an adhesive layer is interposed between them.

Thickness of low elastic modulus resin layer is tL, thickness of high elastic modulus resin layer -'
From the standpoint of heat sealing performance, tear resistance at the score section, and corrosion resistance at the processed section, t L + t H = 20 to 200 microns tL/1H =
It is particularly desirable that there be a relationship satisfying 0.1 to 0.6.

In the present invention, the olefin resin inner material of the two layers 1o and 11 is formed by coextruding two types of resin through a multilayer die and forming a film using a T-die method, an inflation film forming method, etc. However, it is of course possible to use a laminate of separately formed 2N films, or a two-layer co-extruded melt may be applied by extrusion coating onto a metal foil.

From the viewpoint of gas barrier properties, pressure resistance, drop impact resistance, etc., it is important that the score 6 is provided so as to reach the middle of the thickness direction of the metal foil 9. The depth of the score B must be such that the thickness of the metal foil remaining in the score part is 2 μm or more, particularly 60 μm or more.

In the present invention, light metal foil such as aluminum foil is preferably used as the metal foil, but it is of course possible to use iron foil, steel foil, tin foil, etc. From the viewpoint of heat sterilization resistance, it is preferable that these metal foils undergo pretreatment such as alumite treatment, boehmite treatment, chemical treatment with phosphoric acid and/or chromic acid, or chemical conversion treatment.

The metal foil needs to have some stiffness so that it can be torn at the score, and from this point of view, 50
It is desirable to have a thickness of μ or more, particularly 80 μ or more. The upper limit of the thickness of the metal foil is 200μ or less, especially 1
It is desirable that the thickness be 50μ or less.

The depth for a score of 6 is determined by the thickness of the metal foil from 6/10 to 7/10, especially from 215 to 61, from the viewpoint of the above characteristics and ease of opening.
It is preferably in the range of 5.

As the adhesive layer 12, acid-modified ethylene thread or propylene thread resin is preferably used, but other known adhesives such as isocyanate adhesives can also be used.

However, if the low modulus resin layer 10 has adhesive properties to metal foil, it goes without saying that there is no need to provide a special adhesive layer 12.

Moreover, as the resin protective layer 16 in FIGS. 6 to 4,
High tensile plastic films such as biaxially oriented polyester film, biaxially oriented polypropylene film, and biaxially oriented nylon film, epoxy-7 enol paint, epoxy urea paint, epoxy-melamine paint, vinyl ml+, and acrylic paint. A coating film such as epoxy-acrylic paint is used.

In the molding of the container lid of the present invention, drawing molding refers to molding that does not cause any change in the thickness of the product that constitutes the lid, while stretch molding refers to a change in the thickness of the deformed part. (
(reduction) is occurring. In the former, molding is performed without the area around the deformed part being fixed;
In the latter case, molding is performed with this periphery fixed.

The shape of the score can be set in the form of a small circle or raindrop only in a part of the center panel, or it can be set in any shape such as a circle, square, or rectangle so as to open the entire center panel. obtain.

5 and 6 show other examples of the container lid of the present invention, in which the score 6 is provided in a circular shape so that the entire center panel portion 6 can be opened.

The opening tab 8 has a valve fitting tip 27, and the center panel 6 is inserted so that the tip 27 matches the score 6.
It is bonded to the fulcrum 28 at the fulcrum 28.

A recess 60 is provided in the center panel 6 via the overhang molded portion 29, and the grip ring 14 of the opening tab 8 can be easily gripped at the position of the recess 60.

This easy-to-open container lid 1 is also used for sealing by heat sealing a cup-shaped container 64 that includes a tapered side wall portion 61, a bottom portion 62 connected thereto, and a seven-center portion 63 provided at the upper end of the wall portion. obtain.

In the present invention, the container body includes a plastic cup container, particularly a plastic cup formed by vacuum forming, a uniaxially or biaxially stretched plastic cup formed by plug assist molding, reciprocal molding, etc., a metal foil container, a metal foil/plastic composite container, a metal foil/plastic cup, etc. Examples include paper/plastic composite containers.

The heat-sealing conditions are a temperature higher than the melting point of the heat-sealable inner material, and a pressure of generally 1 to 10 kli'/c.
The heat sealing operation is carried out under pressure of "m" gauge.
For example, this can be easily carried out using a heat sealing means known per se, such as a heat seal bar or high frequency induction heating.

The heat seal part of the container of the present invention can withstand sterilization operations such as hot filling, boiling water sterilization, and retort sterilization, and has a high degree of sealing reliability. It has the advantage that it can be stored stably over a long period of time and can be opened easily and reliably.

The excellent effects of the present invention will be explained with the following examples.

Examples 1 to 6 Using the materials shown in Table 2, a laminated sheet having the structure of outer NI/aluminum foil/adhesive layer/low tensile modulus resin inner layer/high tensile modulus resin inner material was prepared in Examples 1 to 6. 1 is powder
Lamination was carried out by a coat lamination method, Example 2 by an extrusion coat lamination method, and Example 6 by a dry lamination method.

Circular blanks were punched out from these laminated sheets, and the first
As shown in the figure, the panel was formed into a drop-lid shape by drawing, and then a bead was formed at the center of the panel by stretch molding. A liquid po type score was applied to the panel part, and a small hole with a diameter of 5.5 mm was punched in the center.

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

The rivet part of this opening tab is inserted into the small hole in the middle part of the middle lid, and the rivet head mf is molded as shown in Figure 4 using the ultrasonic betting method, and the inner resin layer is formed by high-frequency heating. I made her wear a bathing suit.

The six types of molded score lids obtained in this manner were loaded into an enamel later, and the inner surface material was chlorinated. When a voltage of 15V was applied between the electrolyte and the metal foil for 5 minutes using the aluminum foil with some of the paint peeled off as an anode, the enamel rate value was 0.00m in both cases.
It was A. Therefore, the aluminum foil surface was not exposed due to cracks occurring in the inner surface material due to panel molding and bead processing.

Next, for Examples 1 and 6, polypropylene/paper/polypropylene/aluminum foil/polypropylene, and for Example 2, polyethylene/paper/polyethylene/aluminum foil/
Made of polyethylene laminate material with a diameter of 55mmφ
The height of the can body is 162 cm, and both ends are curled.The opening curl part of the combo type can body, as shown in Figure 2, has the same material composition as the score lid, but the score processing and tab attachment are processed. The bottom cover, which was not coated with 5, was first sealed using a high-frequency sealer. This container body was filled with orange juice containing 50% fruit juice heated to 80° C., and each liquid paw-shaped score lid obtained in the previous step was sealed to the curled portion of the opening of the can body using a high-frequency sealer.

When each 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 a predetermined score line. The condition of the opening after opening was good, with no defects such as delamination or feathering.

Separately, when we observed the condition of the molded part on the inner surface of the lid of each container filled with the contents after being left at room temperature for 6 months, no corrosion of the aluminum foil was observed. In addition, when we conducted a test to see if aluminum was present in the juice, no aluminum was detected. Further, when each container was opened after being aged for 6 months at room temperature, the opening was performed smoothly along the score line, and no delamination or feathering occurred.

Comparative Example 1 In Example 1, 16 having a high tensile modulus was used as the inner material.
,000' to 9/crn2, melting point 165℃, MI
When using a single layer polypropylene film with a density of 9 fi/min and a density of 0.90.9/ω, the panel molding area and bead processing area turned white, and the enamel plate
When the aluminum exposure was examined under the same conditions as in Example 1, the enamel rate value was 2.10 rnA.

In addition, when a test was carried out at room temperature for 6 months in the same manner as in Example 1 using 50% orange juice as the content, corrosion of the aluminum foil was observed in the panel molding part and the bead processing part. Furthermore, when the amount of aluminum eluted was measured, it was detected to be 5.2 ppm.

Comparative Example 2゜In Example 1, 4, which has a low tensile modulus as an inner material,
500 kg/crn”, Ml is 71/10 m1n,
When a single layer polypropylene film with a dense FK force of 0-9 Q t /cc was used, no whitening occurred during panel molding and bead processing, and the enamel rate value under the same conditions as in Example 1 was also 0.0 mA. , there was no aluminum exposure. However, when the container was opened from the ring tab of the lid filled with the contents, feathering occurred and it was difficult to open the container smoothly along the score.

Example 4゜Thickness 10 with epoxy phenol vermilion coating applied to the outer surface
The carboxyl group concentration of maleic anhydride grafted onto the unpainted surface of 0 μ soft aluminum foil is 200 meq.
/100. ! i' polymer, melting point 162°C, At I
Ka20? / 10 m1nt7) Degeneration ho! J Prohylene 4ON amount%, ethylene content 6 mol%, melting point 1
47°C, 56% by weight of ethylene-propylene random copolymer with Ml of 189/10mln and melting point of 109°C
, density is 0.919 tree, Ml is '2-09
/ 10 min of a blend of 7% by weight of low density polyethylene 'E-[using a first extruder with a screw diameter of 65mm, and a density of 0.9Of/gloss 1. Isotactic polypropylene with a melting point of 162°C and a Ml of 9.0 f 710 min is extruded from a T-shaped 2N die whose temperature is maintained at 250°C using a second extruder with a 9° diameter screw. Co-pressing was performed, and a temporary bulking body was obtained by pressing with a cooling roll and a nip roll. This tentative bulk is heat-treated in an oven maintained at 220°C and then cooled to room temperature with a cooling roll, so that the structure of the outer layer/
A laminated sheet of 100 μm aluminum foil/25 μm modified polypropylene blend layer/65 μm polypropylene layer was obtained.

Separately, films of a modified polypropylene blend and isotactic polypropylene were prepared, and their tensile moduli were measured to be 6,700 kg/cIIL2 and 16,500 kg/cIIL2, respectively.

A circular blank is punched out from this laminated sheet, and a panel is formed by the stretch molding method as shown in Figures 5 and 6.
Full oven type score processing was applied. Next, an aluminum opening tab was bonded to the nylon with an adhesive at the position shown in FIG. 5 on the panel portion by high-frequency induction heating.

The enamel rate value of the molded score lid thus obtained under the same conditions as in Example 1 was measured to be 0.OOmA, and no aluminum exposure due to panel molding was observed.

Next, a cup as shown in FIG. 6, which was molded from a laminated sheet of epoxyphenol-based 31/120 μm aluminum foil/70 μm polypropylene, was filled with orange jelly, and the molded score lid was sealed with a high-frequency sealer.

When the sealed container filled with the contents was heated and sterilized at IIO° C. for 60 minutes and then opened from the tab, the container could be opened smoothly along the predetermined score line. The condition of the opening after opening was good, with no defects such as delamination or feathering.

Separately, when we observed the condition of the molded part on the inner surface of the lid of a container filled with the contents and heat sterilized after being left at room temperature for 6 months, no corrosion of the aluminum foil was observed. Furthermore, when the amount of aluminum eluted into the contents was measured, it was not detected. Furthermore, when the aged sample was opened from the tab, there were no defects such as delamination or feathering, and the opening could be carried out smoothly according to the score.

Example 5: Thickness: 100 mm coated with epoxy phenol thread paint on the outer surface
Between the uncoated side of the soft aluminum foil of μ and the ethylene-propylene random copolymer side of the polypropylene two-layer coextruded film used in Example 1, The polypropylene blend was melt-extruded from a T-die using an extruder with a screw with a diameter of 90 mm under conditions where the resin temperature at the die part was 260°C, and the mixture was compressed with a cooling roll and a nip roll to perform temporary bonding. Ta. Next, this temporary bonded body was passed through an oven maintained at a temperature of 220°C, and then rapidly pressurized with a cooling roll and a nip roll, so that the composition was (external paint/100 μm aluminum foil/10 μm maleic anhydride-modified polybrohylene). A laminated sheet having a single layer of 20 μm ethylene-propylene random copolymer layer and a 60 μm polypropylene layer was obtained.

A molded score lid similar to that in Example 4 was exploded from the obtained laminated sheet and a test similar to that in Example 4 was conducted, and no problems occurred.

Example 6゜ Instead of the two-layer coextruded film of low density polyethylene and high density polyethylene in Example 2, a tensile density of 0.920 was used.
．． r/cc 15 μm thick low density polyethylene layer, tensile modulus 14.000'Q/cm2, melting point 162
°C, density 0.955 r/cc, MIo, 5f/10
When a two-layer coextruded film of 35 μm thick resin blend Yanabi with m5n high-density polyethylene 60% by weight and talc 40% by weight was used, although the first layer of the Merck blend was slightly whitened due to molding, the Example The enamel rate value under the same conditions as 1 is 0. OOmA, and no aluminum exposure was observed. Similar to Example 2, the test results for opening performance and resistance to contents were also good, with no problems at all.

Comparative Example 6 In place of the two-layer coextruded film of ethylene-propylene random copolymer/polypropylene in Example 6, the melting point was 162°C and the density was 0.955? /crn”, M
A film with a thickness of 50 μm made of a resin blend of 60% by weight of high-density polyethylene with a l of 0-59/10 min and 40% of talc was used, and the enamel rate value was measured under the same conditions as in Example 1. So 1.80mA
Met.

In addition, when a test was carried out at room temperature for 6 months in the same manner as in Example 1 using 50% orange juice as the content, corrosion of the aluminum foil was observed in the panel molding area and the bead processing area. Furthermore, when the amount of aluminum eluted was measured, 4''9 pptn was detected.

[Brief explanation of the drawing]

1 is a plan view of a lid which is a specific example of the present invention; FIG. 2 is a sectional view showing the structure of a container obtained by heat-sealing the lid of FIG. 1; The figure is an enlarged sectional view of the annular rim molded part A of the lid shown in FIG. 2, FIG. 4 is an enlarged sectional view of the tab attachment part B of the lid shown in FIG. 2, and FIG. FIG. 6 is a plan view of an intangible body that is another specific example of the present invention. FIG. 6 is a sectional view showing the structure of a container in which the lid shown in FIG. 2 is the peripheral area to be heat sealed,
6 is the center panel part, 4 is the annular rim part. 6 is a score, 7 is a rib, 8 is an opening tab, 9 is a metal foil base, 10 and 11 are heat-sealable inner materials, 12 is an adhesive layer, 16 is a protective coating layer, 14 is a ring-shaped gripping portion, 15
is the tear start part of the score, 16 is the small hole, 17 is the rivet,
Reference numeral 18 indicates a tip portion protruding from the inner surface of the rivet, 19 indicates a cylindrical body of the container body, 20 indicates a bottom portion, 21 indicates a paper substrate, 22 indicates a metal foil, 26 indicates a heat-sealable inner material, and 24 indicates a heat-sealable resin. 25 is a heat-sealable protective resin layer, 26 is a flange portion, 27 is a valve fitting tip, 28 is a fulcrum, 29 is a stretch molded portion, 60 is a recessed portion, 61 is a tapered side wall portion, 6
2 indicates the bottom portion, and 66 indicates the 7th centimeter portion. Patent applicant Akiyo Kishimoto Patent attorney Ikuo Suzuki 71, 2-1-2)

Claims (1)

[Claims] (1) An easy-to-open heat-sealable lid for sealing the container body by forming a heat-sealing portion with the container body, the iron lid being made of a laminate of a metal foil base and a heat-sealable inner material. (b) The laminate has a score engraved halfway in the thickness direction of the metal foil to define a peripheral part to be heat-sealed and a part to be opened inward from the peripheral part. and a portion that is deformed by molding in the thickness direction of the laminate,
The inner surface material is characterized by having a laminated structure of an olefin resin layer having a relatively high tensile modulus on the innermost surface ζ and another olefin resin layer having a relatively low tensile modulus on the metal foil side ζ. The combination of easy opening and corrosion resistance makes this an excellent heat seal lid.