JPS63236634A - Easy-open heat-seal cover and manufacture thereof - 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 (Field of Industrial Application) The present invention relates to an easy-to-open heat-sealable lid and a method for manufacturing the same, and more particularly, to an easy-to-open heat-sealable lid that can be easily applied to retort sterilization packaging. This invention relates to a heat-sealable lid and its manufacturing method.

(Prior Art) Conventionally, heat-seal lids made of a laminate of a lid base material such as metal foil and a heat-sealable lid inner material such as polyolefin resin film have been widely used in many fields such as food packaging. In particular, those that can be peeled off at the heat seal interface are widely used as easily openable or peelable heat seal lids.

Among heat-sealed packages, the seal strength of the heat-sealed part is 2.3 for those whose contents have been subjected to retort sterilization treatment.
When the seal strength between the container body and the lid reaches this value, it becomes difficult to manually peel off the heat-sealed interface between the two.

To solve this problem, an easily peelable heat-sealable inner material layer is provided on the inner surface of the container body, and a score is provided to cut this inner material layer closer to the center than the heat-sealed part. A heat-sealed container has already been proposed which has a heat-seal strength of 2.3 and a width of 715 mm or more, and which can be easily opened from the outside.

(Problems to be Solved by the Invention) The above-mentioned easy-to-open heat-sealed container has a sealing strength of 2.
．． It is significant as it provides easy-to-open packaging while maintaining a width of 3 kg or more than 715 mm.
The problem is that the container itself must have a laminated structure of a base material and an easily peelable inner surface material layer, and the container must be subjected to score processing, which imposes restrictions on the construction and manufacturing of the container. In addition, in order to score the inside of the heat-sealing periphery, the area of the container flange inevitably increases, resulting in an increase in the amount of container material used, an increase in the bulk of the package, and poor appearance characteristics. Undesirable.

It is possible to form a heat-sealed part with a heat-sealing strength of 2.3 kg/15 mm or more between the container and the container,
Moreover, if a heat-sealable lid with easy-to-open performance is provided, this heat-sealable lid can be applied to any container configuration or material without any restrictions, providing a significant advantage over the conventional products mentioned above. become.

(Means for Solving the Problems) According to the present invention, in a heat-sealable lid that is made of a laminate of a lid base material and a heat-sealable lid inner surface material, and that is heat-sealed and sealed between the lid base material and the container body. The lid inner material is made of a resin film that can be heat-sealed with a heat seal strength of 2.3 kg/15 mm or more between the container body, and the lid base material and the lid inner material are 50 g/715 mm or more.
/15mm or less, and the inner lid material has a score located at a small distance from the periphery to the center to be heat-sealed to the container body. An easily open heat-sealed lid is provided which has a function in which the lid inner surface material is peeled off, the score is then broken, and the lid is removed. According to the present invention, a resin film that can be heat-sealed with a heat-sealing strength of 2.3 kg/715 mm or more is used as a lid inner material between the container body and the lid base material, and the lamination strength of both is 50 g/15 mm. The process of laminating the sheets so that the lamination strength is 2 kg/15 mm or less is completed, and the lid inner material of the resulting laminated sheet is heated with a laser beam at a position a short distance from the periphery to the center to be heat-sealed. Provided is a method for manufacturing an easy-to-open heat-sealable lid, which is characterized by irradiating and carving a score that does not reach the lid base material.

(Function) In FIG. 1 showing the cross-sectional structure of an example of an easily open heat-sealable lid of the present invention, this heat-sealed lid 1 has a lid base material 2
and a heat-sealable lid inner surface material 4 bonded together via an adhesive layer 3 if necessary.

In the present invention, (1) there are two parts between the inner lid material 4 and the container body;
．． 3. Constructed from a resin film that can be heat-sealed with a heat-sealing strength of 8715 mm or more, and 2. Lid base material 2 and lid inner material 4 with a width of 50 g/15 mm or more.
laminated so as to have a lamination strength of not more than m width, and ■ a position with a small distance d toward the center from the peripheral part 5 to be heat-sealed with the container body (see 10 in Figure 2) with respect to the inner lid material 4; A score of 6 is set for .

In FIG. 2 illustrating a state in which this heat seal M1 is applied to a container, the container 10 has a bottom portion 11, a circumferential side wall portion 12,
It has a flange portion 13 on its outer periphery, and is provided with a content storage space 14.

After filling the container 10 with a predetermined content, the heat-sealing lid 1 is applied to the upper part of the container 10, and sealing is performed by heat-sealing between the heat-sealing peripheral portion 5 of the lid 1 and the container flange portion 13. .

When unsealing, the lid base material 2 is pulled upward from the peeling start part 7 provided at one end of the heat-sealed lid 1. Seal strength between lid inner material 4 and container flange portion 13 and lid inner material 4
The lamination strength of the lid base material 2 and the lid base material 2 are in the above-mentioned relationship (1) and (2), with the latter strength being smaller than the former strength;
Moreover, since the latter laminate strength is in a strength range called easily peelable adhesive, peeling between the lid base material 2 and the lid inner surface material 4 easily progresses. When this peeling position reaches score 6, the lid inner material 4 is completely cut or weakened at this score position, so the lid inner material piece is cut off from the lid base material 2 that has been peeled off. be dropped. That is, the lid inner material portion 8 on the outer peripheral side of the score 6 remains attached to the container body 10, while the lid inner material portion 9 on the center side than the score 6 is removed from the container while attached to the lid base material 2. It will be removed.

When attempting to peel off the heat-sealed lid 1 from the content-containing side of the container, as shown in (2) above, since the score 6 is provided at a distance d from the heat-sealed portion toward the center, there is no risk of breakage or breakage at the score portion. No peeling occurred, and the sealing strength was maintained at 2.3 Kg/15 mm width or more as specified in (3).

In the heat seal lid of the present invention, it is important that at the position of score 6, only the lid inner material 4 is separated without the lid base material 2 being broken. For this purpose, the scores 6 are engraved over the entire thickness of the inner lid material 4 or halfway through the thickness, but it is important that the scores do not reach the base material 2.

In a method of performing mechanical scoring such as processing using a normal score die, it is inevitable that the lid base material 2 will also be scored. According to the present invention, by performing score processing by irradiating the lid inner surface material with a laser beam, it becomes possible to engrave the score only on the lid inner surface material.

(Description of structure) The base material for the single-unit lid body includes metal foil such as aluminum foil, tin foil, steel foil, and tin foil, biaxially stretched polyethylene terephthalate film, biaxially stretched nylon film, polycarbonate film, etc. Thermoplastic resin films, various papers, or laminates thereof are used. In the case of transparent lids, film base materials such as nylon and polyester are used, while in the case of lids that strictly require gas barrier properties, aluminum foil, or aluminum foil and film or paper are used. laminate is used as the substrate. Furthermore, for lids that require transparency and gas barrier properties, a gas barrier resin such as ethylene-vinyl alcohol copolymer or polyvinylidene chloride is used as a constituent layer of the base material.

Of course, the outer surface of the lid base material may be provided with printing, a protective coating, or the like.

5 Δ Dish M The lid inner material is composed of a thermoplastic resin film having heat-sealing properties, such as low-1 medium- or high-density polyethylene, tactical polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate. Olefin resins such as copolymers, olefin resins graft-modified with ethylenically unsaturated carboxylic acids or their anhydrides;
Relatively low melting point or low softening point polyamide or copolyamide resin: A film of relatively low melting point or low softening point polyester or copolyester resin is used.

One of these heat-sealing resins is appropriately selected depending on the type of the heat-sealing inner surface of the container body. If the resin constituting the heat-sealing inner surface of the container is a heat-sealable resin, a sealing strength of 2.3 kg/15 mm or more can be easily obtained by using the same type of resin as the lid inner material. You can do it. In addition, even if the heat-sealing inner surface of the container is made of painted metal, by using acid-modified olefin resin, polyamide resin, or polyester resin as the lid inner material, it is possible to reduce g715 mm to 2.3 mm.
A seal strength greater than the width can be obtained.

For sterilization applications at relatively low temperatures, a sealant layer with a relatively melting point such as polyethylene can be used; however, for applications for retort sterilization at high temperatures, propylene resins such as polypropylene, polyamide-based or polyester-based sealants can be used. It is desirable to use a heat sealant. It is desirable that the lid inner surface material generally has a thickness of 10 to 150 μm, particularly 30 to 100 μm.

The original lid base material and the lid inner material are 50g/15mm or more at 2K.
g715 mm or less to form a lid material. If the base material and the inner surface material can be directly laminated and the lamination strength is within the above range, no special measures are necessary, but in general, it is best to select an adhesive between the base material and the inner surface material. This makes it easy to adjust the lamination strength.

For example, in the case of an olefin resin inner material, a blend of an acid or acid anhydride-modified olefin resin and an unmodified olefin resin is used as an adhesive, and by changing the carboxyl concentration in this adhesive, The laminate strength can be controlled within a certain range. In general, = c o ! in this adhesive. 1 degree is 0.1 to 50 rn-
A range of mol/100 g resin is recommended. In addition, an adhesive brimer containing an acid or acid anhydride-modified olefin resin is applied to the lid base material.
It is also possible to thermally bond the resin film through this adhesive brimer, but in this case as well, the desired laminate strength can be obtained by varying the concentration of the modified resin.

The laminate can be manufactured by any means such as thermal adhesive lamination, sandwich lamination, extrusion coating lamination, adhesive lamination, etc.

After or prior to shearing the 522-piece laminate into the desired heat-sealed lid shape, it is subjected to scoring using a laser beam.

The wavelength of the laser beam for score processing is 10.6.
A μm CO2 laser is advantageously used.

That is, this laser has the advantage of being able to process in air and in the form of continuous or rapidly repeating pulses.

The score processing is performed by irradiating the lid inner surface material with the laser beam and relatively moving the laser beam and the inner surface material along the score pattern to be carved. The relationship between the laser output and the line speed during score processing varies depending on the thickness of the inner lid material and the depth of the score to be carved, but generally the line speed (m/mm2) per unit energy density (W/mm2) win), 0.5 to 5
00, especially from the range of 1 to 100, it is preferable to select a condition in which only the lid inner surface material receives a score. It was found that the score formed on the lid inner material by laser beam irradiation had a roughly semicircular cross-sectional shape and functioned satisfactorily as a score.

The score pattern applied to the inner surface of the lid has a shape that is almost similar to the outer periphery of the seal, but rather than being a closed circle or a closed square, this score pattern is more similar to the shape of the start of score engraving, as shown in Figure 3. It is desirable that there be a slight interval 6c between the point 6a and the score engraving end point 6b. This is because if the score pattern is in a closed shape, there will necessarily be an overlapping portion of the laser beams, and in this overlapping portion, the score will be engraved on the lid base material.

Further, the score pattern applied to the lid inner surface material may be divided into two by 6d, de and 6f, ag, as shown in FIG. With this kind of score pattern, it is possible to continuously move the lid material web in a straight line and irradiate the laser beam while vibrating in a direction perpendicular to this, making it possible to efficiently engrave scores on the inner surface material. It can be done accurately.

In the heat seal lid of the present invention, the opening start position 7 is
It is formed by providing a non-bonded portion between the lid base material and the lid inner surface material at one end of the heat seal lid. This non-bonded part is formed by not performing thermal bonding in this part, or by providing a releasable intervening layer between the two only in this part.

In addition, as shown in FIG. 5, a notch 15 is provided that extends through the container flange portion 13 and the lid inner material 4 to the surface of the lid base material 2, and by bending this notch portion, an opening starting portion is formed. You may also do so.

(Effect of the invention) According to the present invention, the distance between the container and the container is 2 to 3 g/15+nm.
A heat-sealed lid that can form a heat-sealed portion with a sealing strength greater than its width and that can be easily opened by hand can be provided with a simple mechanism and at a low cost, and this sealed lid can be attached to any retort sterilization container. It has the advantage of being applicable.

Example 1 A 12-μm biaxially stretched polyethylene terephthalate film and a 50-μm soft aluminum foil were laminated with a urethane adhesive, and the aluminum foil surface of the base material was heated with a two-layer coextrusion die with an Ml of 20 and a carbonyl group concentration of 10 n-mol.
/100g resin of maleic anhydride modified polypropylene and isotactic polypropylene with MI of 22 and density of 0.90 blended with isotactic polypropylene with MI of 22 and density of 0.90. Extrusion coating was applied so that the physical side was on the aluminum side, and two layers of inner material, each having a thickness of 10 μm and 50 μm, were temporarily adhered. Next, this tentatively stacked carcass was heat-treated in an oven at 200° C. to perform main bonding. The lamination strength between the aluminum foil and the maleic anhydride-modified polypropylene blend layer of the obtained laminate was measured and found to be 780 g/15 mm.

Next is a CO with an output of 30 watts and a beam diameter of 0.15 mmφ.

By irradiating the polypropylene side of the laminate with a laser beam at a speed of 30 m/win, the diameter was reduced to 65 mm.
A circular score with φ and a depth of 50 am was provided.

A lid having a diameter of 75 mm, concentric with the score shape, and having a tab portion as shown in FIG. 3 was punched out from the lid material thus obtained.

Separately, 5 layers of 3 types of polypropylene/maleic anhydride-modified polypropylene/ethylene-vinyl alcohol combination/maleic anhydride-modified polypropylene/polypropylene are thermoformed from a coextruded sheet with a thickness of 500 μm, and the inner diameter is 67 mmφ and the outer diameter is 67 mmφ. Diameter is 75mmφ, height is 300m
A cup having a flange shape as shown in FIG. 5 was molded at m.

This molded cup was filled with coffee jelly, and the lid was heat-sealed to the flange. Next, an opening notch as shown in FIG. 5 was provided from the cup side of the heat-sealed tab portion. Thereafter, this packing density container was heated to 120°C.
Retort sterilization treatment was performed for 30 minutes.

When the thus obtained filled and sealed container was opened from the tab portion having the opening notch, it was found that the container could be opened easily.

On the other hand, when the heat seal strength from the center side of the lid was measured, it was 7.2 g/15 mm, which is considerably higher than the JAS standard of 2 and 3 g/15 mm.

Example 2 12 μm biaxially oriented polyethylene terephthalate and 50 μm
An epoxyphenol-based material containing 10 parts by weight of maleic anhydride-modified polypropylene with a thickness of 6 μm and a carbonyl group concentration of 10 m-mol/100 g resin is attached to the aluminum side of the base material, which is made by laminating soft aluminum foil with a thickness of 6 μm using a urethane adhesive. Paint was applied and baked.

Next, an ethylene-propylene copolymer film with a thickness of 70 μm, an ethylene content of 5 mo1%, a density of 0.90, and a melting point of 157°C was applied to the paint-applied surface of the base material using a hot roll, leaving an unpressed portion at the edge. Thermal lamination was performed. The lamination strength of the base material and polypropylene inner material of the obtained laminate was measured and found to be 540 g/15 mm.

A lid material having a diameter of 651111111φ and having a tab portion, the tab portion being an unpressed portion, that is, an unbonded portion, was punched out from this laminate.

Next, by irradiating the polypropylene inner material side of the laminate at a speed of 30 m/min using a CO laser beam with an output of 40 watts and a beam diameter of 0.15 mm in a circle concentric with the outer shape of the lid material, the diameter of the polypropylene inner material was 65 mm. and the depth is 6
A score of 0 μm was engraved.

Separately, a cup as shown in FIG. 2 with an inner diameter of 66 mm, an outer diameter of 77 mm, and a height of 30 mm was molded from a 75 μm rolled steel foil laminated with 40 μm of titanium white-containing polypropylene on both sides using a urethane adhesive.

This molded cup was filled with yakitori, the lid was heat-sealed as shown in FIG. 2, and then retort sterilized at 135° C. for 20 minutes.

When the thus obtained sealed and filled container was opened between the aluminum base material of the tab part and the polypropylene inner surface material, that is, the part shown in FIG. 2, it was possible to easily open the container with a very low opening force. On the other hand, when the heat seal strength from the center side of the lid was measured, a high strength of 7.5 Kg/15 mm was obtained.

Example 3 A 25 μm biaxially stretched polyethylene terephthalate film and a 40 μm soft aluminum foil were laminated with a urethane adhesive, and a 10 μm thick high-density polyethylene and a 60 μm thick isotactic film were applied to the aluminum foil surface of the base material.
A coextruded film with polypropylene was laminated using a urethane adhesive in a positional relationship such that the high-density polyethylene side was the aluminum side. The laminate strength between the high-density polyethylene layer and the inner isotactic polypropylene layer of the obtained laminate was measured and was found to be 200.
g/15mm.

Using the thus obtained lid material, scores were engraved in the same manner as in Example 1 to produce a lid, and a sealed container filled with coffee jelly was produced in the same manner as in Example 1. Retort sterilization treatment was performed under the same conditions as 1.

When this filled and sealed container was opened from the tab portion having the opening notch, the opening force was very low and the container could be opened easily. On the other hand, when the heat seal strength from the center side of the lid was measured, it was a high value of 6.2 kg and 715 mm, indicating that the sealing performance was sufficient.

Comparative Example 1 A similar substrate was prepared in Example 1 using only the same maleic anhydride-modified polypropylene instead of the blend of maleic anhydride-modified polypropylene and isotactic polypropylene. When the lamination strength between the aluminum foil and the maleic anhydride-modified polypropylene blend layer of the obtained laminate was measured, it was 2.5g.
/15mm.

When the laminate strength is strong as described above, when an attempt was made to open the filled and sealed container from the tab portion having the opening notch, it was impossible to open the container.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cross-sectional structure of an example of an easy-to-open heat seal lid of the present invention, FIG. 2 is a diagram illustrating a state in which the heat seal lid is applied to a container, and FIG. , FIG. 4 is a diagram showing an example of a score pattern engraved on the inner lid material, FIG. 4 is a diagram showing different score patterns engraved on the inner lid material, and FIG. FIG. 3 is a diagram illustrating a state in which a heat seal lid is applied to a container. Reference number 1 is the heat seal lid, 2 is the lid base material, 3 is the adhesive layer, 4 is the lid inner material, 5 is the peripheral area to be heat sealed, 6
1 is a score, 10 is a container body, 11 is a container bottom, 12 is a circumferential side wall, 13 is a flange portion, 14 is a content storage space, 1
5 indicates a notch.

Claims (2)

[Claims] (1) In a heat-sealed lid that is made of a laminate of a lid base material and a heat-sealable lid inner material and is heat-sealed to the container body, the lid inner material is placed between the container body and the container body. It is made of a resin film that can be heat-sealed with a heat-sealing strength of 3Kg/15mm or more, and the lid base material and lid inner material are 50g/15mm or more and 2Kg/15mm or more.
It has a lamination strength of 15 mm or less, and the inner lid material has a score located at a small distance from the periphery to the center to be heat-sealed to the container body. When opening, the lid base material and lid An easy-to-open heat-sealed lid that has a function in which the inner surface material is peeled off, the score is then broken, and the lid is removed. (2) A resin film that can be heat-sealed with a heat-sealing strength of 2.3 kg/15 mm or more between the container body and the lid base material is used as a lid inner material, and the lamination strength of both is 2 kg/15 mm or more and the lamination strength is 2 kg/15 mm or more. The process involves laminating the layers so that the lamination strength is 15 mm or less, and the lid inner material of the resulting laminated sheet is irradiated with a laser beam at a position a short distance from the periphery to the center to be heat-sealed to form the lid base. A method for producing an easy-to-open heat-sealed lid characterized by engraving a score that does not reach the wood.