JPH10157034A - Heat sealable lid material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a lid material containing no metal or paper such as aluminum foil, being composed of matierla consisting mainly of plastics, having a superior ability as lid material, as well as water resistivity and heat resistivity, capable of being inspected by a metal detector, having good disposability after use, having almost no curls or static charge, and also capable of being employed excellently even in a filling and sealing machine using sheet lid material. SOLUTION: The lid material is formed such that a lid material foundation sheet 9 is manufactured by employing strength layer 1 made up of plastics as a core material, laminating a biaxially oriented plastic film 2a or 2b on its both surface with an adhesive 4a or 4b, and a heat sealing lid material 10 is composed by extrusion coating and laminating a heat adhesive resin layer 6a as a sealant layer via, e.g. an anchor coat agent ton the surface of the biaxially oriented plastic film 2b to be an inner surface side. For such a strength layer 1, polypropylene, polyester, polyamide, polycarbonate, or the like can be used in a state of a single or laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polypropylene,
Polystyrene, polyethylene or the like, or a heat-sealing lid material used for a molded container made of a laminated sheet and the like with other materials, and more specifically, from the constituent material of the lid material, such as metal such as aluminum foil, paper, It is made of a material mainly composed of plastic, enables inspection of contamination by a metal detector, and has excellent performance such as water resistance, heat resistance, and sealability, and has almost no curl or static charge. The present invention relates to a heat-sealing lid material which has good mechanical suitability for a filling and sealing machine using the above-mentioned lid material, and is also excellent in disposal properties such as incineration after use.

[0002]

2. Description of the Related Art Conventionally, molded containers such as cups and trays have been used for dessert foods such as yogurt, pudding, jelly, ice cream, ice dessert, fruit juice, coffee,
It has been used in a wide range of fields such as liquid drinks such as cocoa and milk drinks, as well as instant noodles, snack foods, and other retort foods. The heat-sealing lid material used for these containers is used under the conditions of use, that is, the contents to be filled,
Depending on the presence or absence of a heat treatment after filling, or distribution conditions, a suitable lid material is selected from various configurations and used.

[0003] As a typical structure of a lid member, for example, the following structure is known. (1) Aluminum foil / adhesive layer / sealant layer (2) Biaxially stretched polyethylene terephthalate film / adhesive / aluminum foil / adhesive layer / sealant layer (3) Paper / adhesive or polyethylene / aluminum foil /
Adhesive layer / sealant layer (4) Paper / adhesive or polyethylene / biaxially stretched plastic film / adhesive layer / sealant layer

In the above structure, a biaxially stretched plastic film may be a biaxially stretched polyethylene terephthalate film, a biaxially stretched nylon film, a biaxially stretched polypropylene film, or the like. In addition, as the sealant layer, polyethylene, polypropylene, or a copolymer thereof, or a mixed resin obtained by blending these resins with another adhesive resin, and the like, and a so-called easy-peel resin, Hot melt adhesives and the like are used. In particular, when using a hot melt, in order to improve the adhesiveness with the substrate sheet surface, a polyolefin resin is first laminated as an adhesive layer,
A method of laminating a hot melt thereon is often used.

[0005]

The structure of the above-mentioned lid material is as follows.
Each has been created in response to the demand for various functions for the lid material, and has characteristics, for example, if the base sheet contains aluminum foil, if the contents are food, After filling and sealing the contents,
There is a problem that inspection with a metal detector, which is performed as part of quality control, cannot be performed to prevent foreign matter from entering.
In addition, in recent environmental problems, there is a problem that, even when incinerated, the waste remains after disposal and the decomposability is poor even in landfill treatment.

[0006] Further, those containing paper in the base sheet are essentially lacking in water resistance, and when used for products that are refrigerated or frozen after distribution after filling, the surface of the lid material absorbs water and becomes uneven. And the appearance is impaired. In addition, the heat resistance and the strength within the paper layer are not always sufficient,
For example, when heat or pressure is applied during heat sealing, there is a problem in that the paper layer may be ignited, or the paper layer may be peeled off when unsealing, so that the entire lid material cannot be peeled cleanly.

[0007] In addition, since the lid material is usually formed of a laminated sheet, there is a common problem that curling is likely to occur, and the sealing device supplies the rolled lid material to perform heat sealing and cutting. In the case of the type of apparatus, there is relatively little problem.However, in the case of the type of apparatus in which a pre-punched sheet of lid material is supplied and heat-sealed, the lid material may be curled or charged with static electricity. There was a problem that the paper was not smoothly supplied one by one from the feeder unit.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to remove a metal such as aluminum foil or paper from a constituent material of a lid material and to mainly use a plastic. In addition to improving the disposability after use, it is also excellent in water resistance, heat resistance, sealability, and almost generates curling and static electricity. Instead, it is an object of the present invention to provide a heat-sealing lid material having good mechanical suitability even for a filling and sealing machine using a single-sheet lid material.

[0009]

The above objects can be achieved by the present invention described below. That is, according to the first aspect of the present invention, two layers are provided on both sides of a strength layer made of plastic.
A heat-melting layer characterized in that a hot-melt layer is provided on one side of a base sheet formed by laminating an axially stretched plastic film via a thermo-adhesive resin layer or an adhesive layer made of a polyolefin-based resin. It consists of a sealing lid material. By adopting such a configuration, the lid member is formed of a material mainly composed of plastic without including metal or paper,
Inspection of foreign substances by a metal detector becomes possible, and in addition to improved disposability, water resistance and heat resistance are improved.
The base sheet is made of a strength layer made of plastic as a core material,
Since a biaxially stretched plastic film is laminated on both sides, a moderate thickness and rigidity are imparted, and a balance between the front and back elasticity due to heat or the like is obtained, so that curling can be prevented. Further, since the outermost layer of the lid member is formed of a biaxially stretched plastic film, the surface properties, that is, the mechanical strength, the scratch resistance, and the suitability for printing in the back printing method can be improved. Further, by providing a hot-melt layer as a sealant layer or an adhesive layer made of a polyolefin-based resin on one surface of the base sheet (the surface that becomes the inside as a lid material), Sealability is provided. In this case, by selecting the material of the thermal adhesive resin layer,
Either easy peel or strong adhesion can be used freely.

[0010] According to a second aspect of the present invention, the strength layer is made of polypropylene, polyester, polycarbonate, polyamide, ethylene / vinyl alcohol copolymer, polyvinyl chloride, polystyrene, and a synthetic material based on polypropylene or polystyrene. The heat-sealing lid material according to claim 1, wherein the heat-sealing lid material is a single layer of paper or a multilayer film containing at least one of these. By forming the strength layer from such a plastic material, a suitable thickness and rigidity can be easily imparted to the cover material, and at the same time, the stability to heat of heat sealing, and a favorable property in the case of a single-sheet cover material. Punching suitability can be reliably obtained.

According to a third aspect of the present invention, the biaxially stretched plastic film of at least the outermost layer of the heat-sealing lid has an antistatic property. It consists of a heat-sealing lid material. By adopting such a configuration, the surface of the lid material is not charged with static electricity, foreign substances such as dust can be prevented from adhering to the lid material, and at the same time, the lid material is punched out one by one. Even in this case, since the lid members do not adhere to each other, even a filling and sealing device for supplying a single-sheet lid member can smoothly supply one sheet at a time without trouble such as two sheets coming out of the feeder.

According to a fourth aspect of the present invention, the heat-sealing lid is in the form of a single sheet punched into a predetermined shape. It consists of a heat-sealing lid material. By adopting such a configuration, as a filling and sealing device, a roll-shaped lid material is supplied and heat-sealed, without being limited to a device for cutting, a lid material punched into individual sheets one by one. Even a device for supplying and heat sealing can be used without any problem, and the range of use of the cover material can be expanded.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the heat-sealing lid material of the present invention, such as a constituent material and a manufacturing method thereof, will be described. In the heat-sealing lid material of the present invention, as described above, metals such as aluminum foil and paper are removed from the constituent materials of the lid material,
It is made of plastic-based material. That is, a strength layer made of plastic is used as a core material, and 2
A base sheet is produced by laminating an axially stretched plastic film, and a heat-adhesive resin layer or an adhesive layer made of a polyolefin resin is used as a sealant layer on one surface (the surface on the inner surface side of the lid material). And a hot melt layer is provided through the intermediary of the cover material.

For the strength layer made of the above plastic, polypropylene, polyester, polycarbonate, polyamide, ethylene / vinyl alcohol copolymer, polyvinyl chloride, polystyrene, or synthetic paper based on polypropylene or polystyrene is used. can do. Each of these may be a single-layer film or a multilayer film containing at least one of them. Further, these films may be stretched and heat-treated, or may be unstretched.

The polypropylene may be a homopolymer of propylene, or a random copolymer of ethylene or ethylene and butene 1, or a block copolymer of ethylene, and the polyester may be polyethylene terephthalate or polybutylene. Terephthalate or the like can be used. In addition, polyamides such as various nylons can be used as the polyamides. In the case of polystyrene, in addition to styrene homopolymer GPPS (general purpose polystyrene), rubber-reinforced HIPS (high impact polystyr)
ene) or SB which is a block copolymer thereof
R (styrene-butadiene rubber) or the like can be used. The thickness of the strength layer as described above is preferably 30 to 120 μm. When the thickness is less than 30 μm, the rigidity is insufficient,
If the thickness exceeds 120 μm, the sealing conditions become severe (high temperature sealing is required to maintain a predetermined sealing speed), so that the lid material is deformed due to shrinkage, etc., and the appearance is impaired, and the seal itself is unstable. Is not preferred.

The biaxially stretched plastic film laminated on both sides of the strength layer is, for example, a biaxially stretched polyester film such as a biaxially stretched polyethylene terephthalate film, a biaxially stretched polybutylene terephthalate film, or a biaxially stretched nylon film. A biaxially stretched polypropylene film or the like can be used, but among them, a biaxially stretched polyethylene terephthalate film is particularly preferable because of its excellent heat resistance, mechanical strength, scratch resistance and the like.

[0017] Then, 2 is applied to both sides of the strength layer serving as the core material.
The method of manufacturing a base sheet by laminating an axially stretched plastic film is to laminate a biaxially stretched plastic film on both sides while melting and extruding the strength layer, depending on a combination of materials of the strength layer and the biaxially stretched plastic film. Although the extrusion lamination method can be used, a method of forming a strength layer in advance and laminating a biaxially stretched plastic film by a dry lamination method using an adhesive on both sides of the film is free from the strength layer material. And at the same time a higher level of performance can be obtained.
It is preferable because the lamination strength is higher and can be stabilized.

By laminating the biaxially stretched plastic film on both sides of the strength layer and forming the base sheet as a laminated sheet having a symmetrical structure on both sides, the thickness and rigidity required for the cover material can be easily increased. As a result, the performance such as heat resistance of the surface can be improved, and the elasticity of the front and back sides can be balanced by heat or the like, so that the occurrence of curling can be minimized.

Further, among the biaxially stretched plastic films on both sides, it is preferable to use a film which has been subjected to an antistatic treatment as at least the outermost layer of the lid material. When the outermost film has an antistatic property, as described above, it is possible to prevent the attachment of foreign substances such as dust, and at the same time, when using a single-sheet lid material,
The lid members do not adhere to each other, so that the suitability for feeder (feeding suitability) in the sealing device can be improved. For the outermost layer of the lid material, a normal biaxially stretched plastic film having no antistatic property can be used, but in this case, the lid material is easily charged in a dry season such as winter, Since the lid members are in close contact with each other, it is necessary to take measures such as attaching a static eliminator to the feeder portion of the sealing device. In this regard,
When a biaxially stretched plastic film having antistatic properties is used, no special device such as a static eliminator is required,
There is an effect that a cover material that can always be stably fed out at the feeder portion can be obtained.

When a picture or the like is to be printed on the lid material, it is necessary to print the inner surface of the outermost biaxially stretched plastic film, that is, the bonding side, by a so-called back printing method. Is protected by a film and is not damaged. When it is desired to add a gas barrier property to the cover material, these biaxially stretched plastic films can be coated with polyvinylidene chloride, or an inorganic thin film other than metal such as silicon oxide can be provided by vapor deposition or the like. .

Next, a sealant layer provided on one side (inner side) of the base sheet produced as described above, that is, a heat-adhesive resin layer or an adhesive layer made of a polyolefin resin is interposed. The hot melt layer provided will be described. The hot-melt material used in the hot-melt layer is generally included in the heat-adhesive resin, but is distinguished from the material in terms of the material and its application method. In the present invention, the heat-adhesive resin used for the sealant layer is not particularly limited, and any known resin having a heat-adhesive property can be used literally. However, as a sealant for the lid material, a strong adhesive sealant from the aspect of functionality,
It can be broadly divided into easy peel sealants.

Examples of the strong adhesive sealant include:
In addition to polyethylene and polypropylene, polyolefin resins such as ethylene / α-olefin copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic ester copolymer, ionomer, polyester resin, A polyamide-based resin and the like can be mentioned, and a suitable resin can be selected from these and used according to the material of the joint portion of the container.

As an easy-peeling sealant,
In addition to known easy-peeling resins, hot-melt materials can also be used as easy-peeling sealants. As the easy peel resin, for example, a resin obtained by blending a polyolefin resin and a styrene resin, or
Further, a resin in which a copolymer of polyolefin and styrene is blended, and a resin in which a tackifier and the like are blended with a polyolefin resin such as an ethylene / vinyl acetate copolymer can be used. Examples of the tackifier include hydrogenated rosin, rosin-based resin, petroleum resin, terpene-based resin, cumarone-indene-styrene-based resin, isoprene-based resin, and the like.

As a method of laminating the above-mentioned strongly adhesive or easy-peeling heat-adhesive resin on a base material sheet, for example, a biaxially stretched plastic film (this (The surface of the film is preliminarily treated for easy adhesion such as corona discharge treatment.)
On the surface of (1), after applying an anchor coating agent, and then directly extruding and coating the thermoadhesive resin with a T-die or the like thereon, and (2) inflation molding the thermoadhesive resin in advance. A method of laminating the film by a dry lamination method using an adhesive, (3) applying an anchor coat agent to the laminated surface in the same manner as in (1), and then applying the heat-adhesive resin film thereon. Are laminated by extrusion lamination (so-called sandwich lamination) using polyethylene or other polyolefin-based resin for the adhesive layer, and any of these methods can be used.

When a hot-melt material is used as the easy-peeling sealant, the method of laminating the base sheet is usually a lamination surface of the base sheet,
In order to enhance the adhesiveness with the biaxially stretched plastic film surface subjected to the easy-adhesion treatment, first, an anchor coat is applied to the laminated surface, and then an adhesive layer made of a polyolefin-based resin is extruded on the laminated surface. And a method of applying a hot melt material thereon by a melt gravure coating method or the like. As another method, an adhesive layer made of the polyolefin resin is formed into a film in advance, and this is laminated on the inner surface of the biaxially stretched plastic film of the base sheet by a dry lamination method via an adhesive. A hot melt material can be laminated thereon by a melt gravure coating method or an extrusion coating method. By adopting such a method, the hot-melt material can be firmly adhered to the base material sheet. You can easily peel the whole material.

In the above, as the polyolefin resin used for the adhesive layer, in addition to polyethylene, the ethylene component is 80 to 95% by weight based on the total resin amount, and the remaining 20 is used.
A copolymer resin containing up to 5% by weight of a carboxylic acid or an ester component thereof can be used. Incidentally, as the carboxylic acid, vinyl acetate, acrylic acid, methacrylic acid and esters thereof are preferable.

It is preferable that the hot melt layer provided on the polyolefin resin layer can be widely applied as an easy-peeling sealant to containers having different joint materials such as polypropylene, polystyrene and polyethylene. From this point, as the hot melt material, for example, 30 to 50% by weight of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 10 to 40% by weight, and waxes (microcrystalline wax alone or other waxes) A mixture of 30 to 40% by weight, 15 to 30% by weight of a tackifier and, if necessary, up to 10% by weight of other additives can be used.

As the tackifier, hydrogenated rosin,
Rosin resin, petroleum resin, terpene resin, cumarone
Indene / styrene-based resins, isoprene-based resins, and the like can be used and can be appropriately selected from these. Other additives are a lubricant, an anti-blocking agent, a heat stabilizer, and the like. Examples of the lubricant and the anti-blocking agent include fatty acid esters, amides, amines, and fine powders of inorganic compounds. Examples of the agent include butylhydroxytoluene, tocopherols, n-octadecyl-β
(4'-Hydroxy3 ', 5-di-t-butylphenyl) propionate and the like, and a suitable one can be selected from these known ones. The coating amount of such a hot melt layer is from 10 g / m ² to 40 g / m ^2.
It is preferably in a range of g / m ^2, typically 20 to 30 g / m ²
It is about.

In the case where the surface of the sealant layer has poor slipperiness, a known embossing means, for example, after heat-softening the sealant layer, the surface is subjected to mat processing or silk-like uneven processing. The surface of the sealant layer is provided with irregularities with a height of several μm to 20 μm by pressing it on a cooling roll that has been subjected to cooling, etc. Suitability can be improved.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings and embodiments. However, the present invention is not limited to these drawings and examples. Further, the same symbols used in the description of the drawings are used for parts having the same name in different drawings. FIGS. 1, 2, 3 and 4 are schematic cross-sectional views each showing the configuration of one embodiment of the heat-sealing lid material of the present invention.

The heat-sealing lid 10 shown in FIG. 1 has a strength layer 1 made of plastic as a core material, and a biaxially stretched plastic film 2a or 2b is laminated on both surfaces thereof via an adhesive 4a or 4b, respectively. A base sheet 9 is prepared by heating, and a heat-adhesive resin layer 6a is laminated by extrusion coating on one surface, that is, an inner surface of the biaxially stretched plastic film 2b via an anchor coating agent 5. It is composed. Note that the anchor coating agent 5 may be omitted when unnecessary.

The heat-sealing lid material 11 shown in FIG. 2 has a strength layer 1 made of plastic as a core material, and has one surface (a surface facing outward) on the laminated surface in advance via an adhesive 4a. 2 having an antistatic property provided with a printed layer 3 such as a picture
An axially stretched plastic film 2c is laminated as an outermost layer, and an inner surface side biaxially stretched plastic film 2b is laminated on the other surface of the strength layer 1 via an adhesive 4b to form a base sheet 9. A thermo-adhesive resin layer 6b previously formed into a film is laminated on the biaxially stretched plastic film 2b on the inner surface side via an adhesive 4c by a dry lamination method.

The heat-sealing lid material 12 shown in FIG.
Using a strength layer 1 made of plastic as a core material, a biaxially stretched plastic film 2a or 2b is laminated on both sides thereof via an adhesive 4a or 4b to form a base sheet 9, and one surface of the base sheet 9 is prepared. An anchor coating agent 5 is applied to the inner surface of the biaxially stretched plastic film 2b.
, An adhesive layer 7 made of a polyolefin resin is laminated by extrusion coating or the like, and a hot melt layer 8 is further laminated thereon by a melt gravure coating method or the like.

The heat-sealable lid 13 shown in FIG. 4 has a strength layer 1 made of plastic as a core material, and one side of the heat-sealing lid 13 is preliminarily printed with a pattern or the like on a laminated surface via an adhesive 4a. An antistatic biaxially stretched plastic film 2c provided with a layer 3 is laminated as the outermost layer, and the other surface of the strength layer 1 is bonded via an adhesive 4b to the inner side of the biaxially stretched plastic film 2b. To form a base sheet 9
Then, an adhesive layer 7 made of a polyolefin resin is laminated on the biaxially stretched plastic film 2b on the inner surface side via an anchor coat agent 5 by extrusion coating or the like, and a hot melt layer 8 is further formed thereon. It is formed by lamination by a melt gravure coating method or the like.

Hereinafter, the present invention will be described specifically with reference to examples. [Example 1] (Easy peeling heat-sealing lid material used for a container in which the joining surface of the lid material is formed of polyethylene) is prepared. The core material of the base sheet, that is, the strength layer has a thickness of 80 µm.
m as a biaxially stretched plastic film to be laminated on both sides of a polypropylene-based synthetic paper. For the outermost layer, a 12 μm thick biaxially stretched polyethylene terephthalate film having antistatic properties [Espet Film T- 6140 (Single-sided corona discharge treatment) Toyobo Co., Ltd.
By using a gravure printing method on the corona discharge treated surface to produce a film. For the inner surface side, a 12 μm-thick biaxially stretched polyethylene terephthalate film [Espet Film T-4200 (double-sided corona discharge treatment) manufactured by Toyobo Co., Ltd.] was prepared.

Then, on one surface of the synthetic paper of the strength layer, a two-component reactive polyurethane-based adhesive was applied by a dry lamination method at a dry application amount of 3 g / m ² , and the espet for the outermost layer was used. The corona discharge-treated surface (pattern printed surface) of the film T-6140 is laminated together, and then
On the other side of the synthetic paper, the espet film T for the inner side is formed by the dry lamination method in the same manner as described above.
-4200 (double-sided corona discharge treatment) was laminated to produce a substrate sheet.

Next, a hot melt material is used as a sealant layer to be laminated on the base sheet.
Add 2 to the surface of the E-4 PET film T-4200
After applying a liquid reaction type polyurethane anchor coating agent [Seikadyne 450A / 3400C manufactured by Dainichi Seika Kogyo Co., Ltd.], low density polyethylene [Mirason 16P manufactured by Mitsui Petrochemical Industry Co., Ltd.] as a polyolefin resin for the adhesive layer. Is extruded and coated to a thickness of 20 μm, and a hot melt material (DX-907 (main component ethylene-vinyl acetate copolymer) manufactured by Dainippon Ink and Chemicals, Inc.) is further applied thereon by a melt gravure coating method. Thus, the heat-sealing lid material sheet of Example 1 was produced by applying such that the application amount became 25 g / m ² . (Hereinafter, a biaxially stretched polyethylene terephthalate film is referred to as a PET film.)

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12 μm / printing layer / adhesive (3 g / m ² ) / polypropylene synthetic paper 80
μm / adhesive (3 g / m ² ) / PET film 12 μm
/ Anchor coating agent / Low density polyethylene layer 20μm /
Hot melt layer (25 g / m ² ) [Total thickness of lid material sheet is about 155 μm]

Example 2 (Easy-peelable heat-sealing lid material used for a container whose lid surface is made of polystyrene is prepared) In the configuration of the heat-sealing lid material sheet of Example 1, 80 μm thick synthetic paper used for the strength layer of the base sheet
A substrate sheet was prepared in the same manner as in Example 1 except that the non-stretched nylon film was replaced with a non-stretched nylon film. Further, a PET film on the inner surface side of the substrate sheet, that is, Espet Film T-4200 (double-sided treatment) A 30 μm-thick easy-peel film for polystyrene (PS) [VM] was coated on the surface by dry lamination using a two-component reactive polyurethane-based adhesive so that the coating amount upon drying was 3 g / m ^2.
X41FT (single-sided corona discharge treatment) Wada Chemical Industry Co., Ltd.
Was used as a sealant layer, the corona-discharge treated surfaces thereof were aligned and laminated, and a heat-sealing lid material sheet of Example 2 was produced.

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12 μm / printing layer / adhesive (3 g / m ² ) / non-stretched nylon film 80
μm / adhesive (3 g / m ² ) / PET film 12 μm
/ Adhesive (3 g / m ² ) / Easy peel film for PS (VMX41FT) 30 μm [Total thickness of lid material sheet is about 143 μm]

Example 3 (Preparing a Strongly Adhesive Heat-Sealable Lid Used for Containers in which the Lid Material is Joined with Polypropylene) The constitution of the heat-sealable lid of Example 2 was as follows: A substrate sheet was prepared in the same manner as in Example 2 except that the 80 μm-thick unstretched nylon film used for the strength layer of the substrate sheet was replaced with an 80 μm-thick unstretched polypropylene film (double-sided corona discharge treatment). Produced, and further, a PET film on the inner surface side of the base sheet, that is, an Espet film T-4
Easy peel film for PS (VMX) with a thickness of 30 μm laminated as a sealant layer on the 200 (both sides treated) surface
The heat sealable lid material sheet of Example 3 was produced by laminating in the same manner as in Example 2 except that the 41FT single-sided corona discharge treatment) was replaced with a non-stretched polypropylene film having a thickness of 30 μm (one-sided corona discharge treatment).

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12 μm / printing layer / adhesive (3 g / m ² ) / unstretched polypropylene film 80 μm / adhesive (3 g / m ² ) / PET film 1
2 μm / adhesive (3 g / m ² ) / non-stretched polypropylene film 30 μm [Total thickness of lid material sheet is about 143 μm]

[Comparative Example 1] (For comparison with Example 1, an easy-peelable heat-sealing lid material used for a container in which the joining surface of the lid material is formed of polyethylene) is prepared. Among the biaxially stretched plastic films laminated on both sides of the strength layer (polypropylene-based synthetic paper having a thickness of 80 μm), the biaxially stretched plastic film on the inner side (PET film 12 μm) in the configuration of the conductive lid material sheet
Except for the above, all were processed in the same manner as in Example 1 to produce a heat-sealing lid material sheet of Comparative Example 1. That is, a printed PET film having an antistatic property as an outermost layer [Espet Film T-6140 (single-sided corona discharge treatment) thickness 12]
μm] is laminated by a dry lamination method using an adhesive, and then an anchor coat agent is applied to the other surface of the synthetic paper, and a low-density polyethylene having a thickness of 20 μm is formed thereon as an adhesive layer. And hot-melt material (DX-907) was applied thereon by a melt gravure coating method so that the coating amount was 25 g / m ² to prepare a heat-sealing lid material sheet. Things.

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12 μm / printing layer / adhesive (3 g / m ² ) / polypropylene synthetic paper 80
μm / anchor coating agent / low density polyethylene layer 20μ
m / hot melt layer (25 g / m ² ) [total thickness of lid material sheet is about 140 μm]

[Comparative Example 2] (For comparison with Example 2, an easy-peelable heat-sealing lid material to be used for a container in which the joining surface of the lid material is formed of polystyrene) is prepared. In the configuration of the conductive lid material sheet, a substrate sheet is produced by replacing the non-stretched nylon film having a thickness of 80 μm used for the strength layer of the substrate sheet with a polystyrene sheet having a thickness of 180 μm (in this case, adhesive for dry lamination). All were coated in the same manner as in Example 2 except that the coating surface of the agent was applied to both sides of the PET film) to produce a heat-sealing lid material sheet of Comparative Example 2.

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12μm / printing layer / adhesive (3g / m ² ) / polystyrene sheet 180μ
m / adhesive (3 g / m ² ) / PET film 12 μm /
Adhesive (3 g / m ² ) / PS easy peel film (VMX41FT) 30 μm [Total thickness of lid material sheet is about 2
43 μm]

[Comparative Example 3] (For comparison with Example 3, a heat-sealing lid material having a strong adhesiveness used for a container having a lid bonding surface made of polypropylene was prepared.) The same as Example 3 except that the 80 μm-thick unstretched polypropylene film used for the strength layer of the base sheet was replaced with a linear low-density polyethylene film having a thickness of 40 μm. Then, a heat-sealing lid material sheet of Comparative Example 3 was produced.

The structure of the heat-sealing lid material sheet is as follows. Antistatic PET film 12 μm / printing layer / adhesive (3 g / m ² ) / linear low density polyethylene film 40 μm / adhesive (3 g / m ² ) / PET film 12 μm / adhesive (3 g / m ² ) / no stretch Polypropylene film 30μm [Total thickness of the lid sheet is about 103μ
m]

[Evaluation Tests and Results] Each of the heat-sealing lid material sheets of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 produced as described above was circularly shaped with a diameter of 80 mm and part of the outer periphery. Each of the test samples was punched out from a lid material having a knob piece and subjected to the following tests.
The number of samples was 5,000 each.

(Evaluation Items and Evaluation Criteria) (1) Suitability for punching ：: No burrs are generated at a predetermined size and punching can be performed satisfactorily ×: Burrs and dimensional defects are generated or workability is poor

(2) Curling resistance Twenty lids were sampled at random for each of the above samples, and placed one by one on a horizontal glass plate in a room at 25 ° C. The height (mm) was measured, and the average value was taken as the curl value. The evaluation criteria for curl resistance are as follows:
When the curl value is 5 mm or less, the mechanical aptitude of the filling and sealing machine is good. When the curl value exceeds 5 mm, poor mechanical aptitude such as a feeder trouble tends to occur.
The results are shown in Table 1 by symbols, in which the result is indicated as good [○] when the value is not more than m and as poor [x] when the value exceeds 5 mm.

(3) Rigidity (Suitability of Filling Machine) As the suitability of the filling material for the lid material, if the rigidity of the sheet material is too low, it will fall off from the feeder portion of the filling and sealing machine at the time of feeding, resulting in poor suitability. Also, even if the rigidity is too high, the repulsive force is so strong that it cannot be supplied smoothly, resulting in poor aptitude. Therefore, the suitability was actually tested on a filling and sealing machine using a single-sheet lid material, and the results are shown in Table 1 by symbols according to the following criteria. ：: Suitable for a filling and sealing machine using a single-sheet lid material having moderate rigidity. ×: Too low or too high for rigidity and not suitable for a filling and sealing machine.

(4) Heat Sealability and Its Appearance The lid material of each sample was prepared by using the following plastic molded container (with an outer diameter of a flange of 79 mm, corresponding to each sealant).
(Flange width: 7 mm) was filled with water, and then heat-sealed using a ring sealer. The heat sealability and appearance were evaluated according to the following criteria.
It was shown to. In addition, the sealant having an easy peel property (Examples 1 and 2 and Comparative Examples 1 and 2) has an easy peel property when the lid material is peeled off after sealing, the presence or absence of transfer of the sealant to the container side, The presence or absence of delamination of the material was also examined. ○: All good in heat seal adhesion and appearance, etc. ×: Some problem in heat seal adhesion, appearance, easy peelability, etc. (Material of flange surface of container used for test) For Example 1 and Comparative Example 1: Polyethylene For Example 2 and Comparative Example 2: Polystyrene For Example 3 and Comparative Example 3: Polypropylene

(5) Water Resistance After the lid material of each sample was immersed in water at room temperature for 24 hours, water resistance such as swelling due to water absorption or delamination was examined.
Those having no change are indicated as good water resistance [O], and those having abnormalities are indicated as poor water resistance [X], and are shown in Table 1 by symbols.

[0055]

[Table 1] (Evaluation results) * 1: The lid material was thick and required a higher sealing temperature, which caused the lid material to shrink and deform, making the seal unstable and inferior in appearance.

As is clear from the results shown in Table 1, the lid materials of Examples 1, 2, and 3 were good in all the evaluation items. On the other hand, the lid material of Comparative Example 1 lacked the biaxially stretched plastic film (PET film 12 μm) on the inner surface side of the base sheet, and thus lacked a balance between the front and back elasticity, and had a large curl. A defect has occurred. And since the lid material of Comparative Example 2 used a polystyrene sheet having a thickness of 180 μm for the strength layer as the core material of the base sheet, the rigidity became too high at the same time as the thickness increased,
The suitability of the feeder was impaired, a high temperature was also required for heat sealing, the shrinkage / deformation of the lid material occurred, the appearance was impaired, and the seal itself became unstable, resulting in poor suitability. In addition, since the lid material of Comparative Example 3 used a linear low-density polyethylene having a thickness of 40 μm for the strength layer of the base sheet, the material was soft and stretched, and burrs were generated at the time of punching, and the thickness was slightly increased. Insufficiency and lack of rigidity caused poor filling machine suitability such as falling off at the feeder section of the filling and sealing machine.

[0057]

As described in detail above, according to the present invention, since the lid is made of a material mainly composed of plastics without using metal such as aluminum foil or paper as a constituent material, the filling material is not filled. Inspection of foreign substances by a metal detector is possible in product inspection after sealing, and at the same time, in terms of performance, it is excellent in water resistance, heat resistance (heat seal stability) and sealing properties, and it is punched one by one Even when used as a cover material, it has almost no curl or static charge, has good mechanical suitability for a wide range of automatic filling and sealing machines, and depending on the choice of sealant, either strong adhesion or easy peeling When an easy-peeling sealant is used, the entire lid can be easily and cleanly peeled off when opened, and it is also easy to incinerate after use. sex An effect that can provide wood.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the configuration of a first example of a heat-sealing lid material of the present invention.

FIG. 2 is a schematic sectional view showing the configuration of a second embodiment of the heat-sealing lid material of the present invention.

FIG. 3 is a schematic sectional view showing the configuration of a third embodiment of the heat-sealing lid material of the present invention.

FIG. 4 is a schematic sectional view showing the configuration of a fourth embodiment of the heat-sealing lid material of the present invention.

[Explanation of symbols]

Reference Signs List 1 Strength layer 2a, 2b Biaxially stretched plastic film 2c Biaxially stretched plastic film having antistatic property 3 Printing layer 4a, 4b, 4c Adhesive 5 Anchor coating agent 6a Thermal adhesive resin layer (extruded coating) 6b Thermal adhesiveness Resin layer (film) 7 Adhesive layer (polyolefin resin) 8 Hot melt layer 9 Base sheet 10, 11, 12, 13 Heat-sealing lid material

Claims (4)

[Claims] 1. A base sheet comprising a biaxially stretched plastic film laminated on both sides of a strength layer made of plastic, and a heat-adhesive resin layer or an adhesive layer made of a polyolefin resin interposed on one surface of the base sheet. A heat-sealing lid material provided with a hot melt layer. 2. The method according to claim 1, wherein the strength layer is any one of polypropylene, polyester, polycarbonate, polyamide, ethylene / vinyl alcohol copolymer, polyvinyl chloride, polystyrene, and synthetic paper based on polypropylene or polystyrene. 2. The heat-sealing lid material according to claim 1, wherein the heat-sealing lid material is a single layer of a kind or a multilayer film containing at least one of these. 3. The heat-sealable lid material having at least an outermost layer 2
3. The heat-sealing lid material according to claim 1, wherein the axially stretched plastic film has an antistatic property. 4. The heat-sealing lid material is in the form of a single sheet punched into a predetermined shape.
The heat-sealing lid material according to any one of the above.