JPS60239238A - Multilayer packaging material - 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 a multilayer packaging material that can be sealed to a wide variety of olefin resins with satisfactory sealing properties and easy opening properties.

For packaging foods such as meat, gas barrier materials are used to preserve the food's shelf life, and multi-layered heat-sealing layers with good sealing properties are used to maintain airtightness during handling during transportation and storage. Gas barrier packaging materials are used. However, when taking out the contents of the package, the seal is stronger than necessary and cannot be opened by hand, so it is difficult to open the package by cutting it with scissors or by tearing it along the tape with a high-strength tape stretched in one direction. There were problems such as the necessity of In response to this, conventionally, it has been considered to use a layer of a specific adhesive resin mixed with a specific different type of resin as a sealing layer of a packaging material to obtain an easy-to-open seal. For example, JP-A-57-131556 discloses a polyolefin resin in which a sealing layer is a layer of polyethylene or an ethylene-vinyl acetate copolymer mixed with polybutene-1, or a sealing layer of H, a mixture of low-density polyethylene and polypropylene. A multilayer film capable of forming an easy-to-open seal as a sealing partner is described. However, although the former mixed layer is useful for polyethylene and ethylene-vinyl acetate copolymers, it cannot provide an easy-to-open seal that satisfies the sealing properties for polypropylene and ionomers, and the latter, polypropylene and low-density Although a sealing layer made of a mixed layer with polyethylene is useful for polyethylene and polypropylene, it does not have sealing properties for ionomers and the like. For example, the latter mixed layer is a packaging material whose inner sealing layer is an ionomer with good oil resistance and transparency necessary for packaging oil-based foods, and an ionomer that is commercially available as a lid material for deep-drawn packaging containers. / Urethane adhesive / Vinylidene chloride copolymer coated cellophane / Urethane adhesive / Polypropylene composition,
Ethylene-vinyl acetate copolymer/urethane adhesive/vinylidene chloride copolymer coated polyester composition, ionomer/urethane adhesive/vinylidene chloride copolymer coated polypropylene composition, or crystals of polypropylene, etc. When a multi-layer lid material with a sealing layer made of highly resistant polyolefin is used as a sealing partner, even if it is easy to open, the sealing performance is poor, and the seal leaks during storage of the package, making it unpractical. In cases such as deep drawing packaging of foods that use various wrinkle materials for production, there is a drawback that the container molding material must be changed each time the lid material is changed.

The present inventors have solved these conventional drawbacks and are able to create easy-to-open seals for a wide range of olefin resin sealants, including polypropylene and ionomers as well as polyethylene and ethylene copolymers, under a wide range of sealing temperature conditions. As a result of intensive research on packaging materials, we have created a sealing layer that is a mixture of a specific ionomer resin and a specific ethylene-propylene copolymer, and now contains ionomer and polypropylene, which was not possible with conventional packaging materials. The present invention was completed based on the discovery that easy-to-open seals can be made with a wide variety of polyolefin resins. That is, the present invention has a melt index of 0.5-100 g/
A seal for a laminate consisting of at least one heat seal layer made by mixing 5 to 65 parts by weight of an ethylene-propylene copolymer with an ethylene content of 1 to 50% by weight to 100 parts by weight of an ionomer resin of 10 m1n. This is a multilayer packaging material that can be easily opened and sealed using an olefin resin as a sealing partner.

In the present invention, an easy-to-open seal refers to one that satisfies practical sealing performance and is easy to open by hand, and is used to heat-seal the heat-sealing layer of the multilayer packaging material and the sealing partner olefin resin. Regarding what you did, 2
As a guideline, perform a T-peel test with a peeling speed of 00II1m/min and obtain a peel strength within the range of 5O-1500(]/151Il1 width under the optimum sealing temperature condition with a range of at least 20℃ or higher. If the peel strength is 50g/15+nm or less, when the contents such as sliced ham are placed in a deep-drawn container, covered with a lid material and made into a deep-drawn package after vacuum degassing, the lid will easily come off due to impact, etc. This is because delamination occurs at the sealed portion between the material and the container material, and on the other hand, if the temperature exceeds 1500o/15mm, it becomes difficult to open the seal by hand.

Further, in the present invention, the melt index is A S
This is a value measured in accordance with TMD-1238.

The ionomer resin used in the present invention includes: (1) Metal salts of tyrene-α/β unsaturated carboxylic acid copolymers, including ethylene, acrylic acid, and methacrylic acid.

It is an ionically crosslinked metal salt polymer derived from a copolymer of crotonic acid, maleic acid, or its derivatives such as acid amides and acid imides. Preferred examples include metal salts of ethylene-acrylic acid copolymer or ethylene-methacrylic acid copolymer, such as commercially available DuPont product name Surlyn and Mitsui Polychemical Co., Ltd.
It can be selected from the product name Himilan (manufactured by Asahi Kaseiko T8 Co., Ltd.) and the product name Corpolen (manufactured by Asahi Kasei Kogyo Co., Ltd.).

The ionomer resin used in the present invention has a melt index of 0.5-1000 for processability and easy-to-open seals.
/ Limited to 10 iin. 0.5Q/101
If it is less than n, the peel strength of the mixed layer will be too high and the mixed layer will not be easy to open, and if it exceeds 100 g/10 m1n, it will be difficult to form a film by conventional industrial means. Furthermore, if the amount of the ethylene-propylene copolymer mixed in the mixed layer exceeds 65 parts by weight based on 100 parts by weight of the ionomer resin, phenomena such as stringiness or bag-like peeling may occur during peeling, which is undesirable. This is because if it is less than 5 parts by weight, the peel strength will not be reduced enough and easy opening will not be achieved.

The ethylene-propylene copolymer used in the present invention is an ethylene-propylene copolymer having an ethylene content of 1-50% by weight, preferably 2-45% by weight in order to obtain good easy-opening properties as a layer mixed with an ionomer resin. It is a combination. Preferably, it can be selected from commercially available ethylene-propylene block copolymers manufactured by Sumitomo Chemical Co., Ltd. under the trade name Noblen AD series, but in addition to ethylene-propylene block copolymers, ordinary films There are also commercially available ethylene-propylene random copolymers, and ethylene-propylene copolymers made by polymerizing a mixed gas of ethylene and propylene using a regular Ziegler-Natsuta catalyst and then treating it with heated hebutane. You can choose.

In the present invention, the laminate consisting of 11f is
Preferably, it is a gas barrier resin layer such as that used for food packaging, but if necessary, it may have impact strength.

Oil resistance 1 Reinforcement layer provided to improve mechanical strength, etc.
and a laminate including an adhesive layer used as an interlayer or surface layer between these layers. Here, the gas barrier resin layer is vinylidene chloride resin.

Saponified ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyamide, polyester, nitrile resin, vinylidene chloride-coated cellophane films, coating sheets and plates, as well as aluminum foil, metal-deposited films, etc. As the reinforcing layer, a gas barrier resin layer having reinforcing properties is used, and vinyl chloride resin, polystyrene, polycarbonate, polyolefin resin, etc. are preferable. As the adhesive layer, ordinary thermoplastic adhesives and thermosetting adhesives can be used, but in particular, between the vinylidene chloride resin gas barrier layer and the polyolefin resin layer, ethylene-vinyl acetate copolymer, chlorinated An unsaturated carboxylic acid graft adhesive of ethylene copolymer or the like is used, if necessary, between the saponified ethylene-vinyl acetate copolymer gas barrier layer such as polyethylene and the polyolefin resin layer.

The method for producing the mixed layer, which is the heat-sealing layer of the multilayer packaging material of the present invention, is preferably to prepare a compound using the tri-blend method using ordinary powder or pellets, and to use this for lamination. Any mixing method may be used, such as a method in which the components are mixed as a homogeneous or heterogeneous liquid using a polymer, or a method in which one of the components to be blended is mixed with the other component during the production of the polymer. Also, the lamination method may be any method such as conventional heat compression dry lamination, melt extrusion coating, coextrusion method, or homogeneous or heterogeneous liquid coating using a solvent or dispersion medium, and may include stretching before or after lamination. It may also include a step of Preferably, a coextrusion method is used since the process is simple.

Since the multilayer packaging material of the present invention described above has a heat-sealing layer consisting of a specific mixed layer, at least ili! In addition to performance such as gas barrier properties obtained by the laminate layer made of Creates an easy-to-open seal. For this reason, in packaging where meat, sliced ham, etc. are placed in a deep-drawn container, covered with a lid and heat-sealed around the container, various commercially available lids with a wide range of polyolefin sealing layers are used. This makes it possible to create an easy-to-open seal, which is extremely useful.

The present invention will be further explained below with reference to Examples.

Examples 1 to 3 and Comparative Examples 1 to 3 In the configuration of outer layer/adhesive layer/core layer/adhesive layer/inner layer, an ionomer resin (manufactured by DuPont, trade name: KEILIN-1601, melt index 1.2g710) was used as the inner layer.
win) Ethylene content is 5% by weight per 100 parts by weight
Ethylene-propylene copolymer (Sumitomo Chemical Co., Ltd.)
11.1 parts by weight (trade name: Noblen S-131° melt index 1.3o/10 m1n) (Example 1)
), 25 parts by weight (Example 2) and 42.85 parts by weight (Example 3), respectively; blend obtained by tri-blending; outer layer made of vinyl chloride resin (manufactured by Kenbetsu Kagaku Kogyo Co., Ltd., product name S-) 9007) Composition containing 7 parts by weight of diethylhexyl azelate per 100 parts by weight, vegetable oil epoxide, calcium/zinc non-toxic stabilizer, and MBS vinegar impact imparting agent: core layer containing ethylene [144 mol%]
, Saponified ethylene-vinyl acetate copolymer with a saponified layer of 98% or more (manufactured by Kuraray Co., Ltd., trade name 1 bar EP-E)
: An adhesive made by graft polymerizing maleic anhydride to an ethylene-vinyl acetate copolymer as an adhesive layer (manufactured by Showa Denko K.K., trade name ER200V-3). It was fed to a coextrusion die by an extruder with a ratio of 28 to obtain a 5-layer film with outer layer/adhesive layer/core layer/adhesive layer/inner layer of 45μ15μ/20μ15μ/60μ with a total thickness of 135μ.

Further, as Comparative Example 1, a 5-layer film was prepared in the same manner as in Example 1 except that the inner layer, which is a heat-sealing layer, was made of only Surlyn, and as Comparative Example 2, the inner layer was made of ionomer resin.
Example 5 was prepared in the same manner as in Example 1, except that the mixture m of the ethylene-propylene copolymer was 81.81 parts by weight, which exceeds the upper limit of the range of the present invention, based on 00 parts by weight.
As a comparative example 3, a 5-layer film was prepared in the same manner as in Example 1 except that the inner layer was made of only the same ethylene-propylene copolymer as in Example 1.

These 5-layer films are made by Taishoku Kikai, product name: FV603.
Using a mold deep drawing vacuum packaging machine, at a drawing temperature of 90°C,
It was molded into a concave container with a diameter of 97111 m and a depth of 20 mm. This container was filled with cylindrical sliced ham, stretched polypropylene (20μ)/vinylidene chloride copolymer coated cellophane (40μ)/Surlyn seal layer (60μ).
Cover the container with a normal composite film for lid material dry-laminated using a polyurethane adhesive with the following composition, and after deaerating the inside of the container, heat seal the seal around the container part at 130 ° C.
Film packages of Examples 1 to 3 and Comparative Examples 1 to 3 were obtained.

For each package obtained, a test piece was cut from the heat-sealed part to evaluate the ease of opening of the sealed part.
Tensile testing machine (product name: UTM-11 manufactured by Toyo Holdwin)
The strength of the peeled crucian carp was measured at a tensile speed of 200 mm/sin using a tensilon (type Tensilon). As a result, the peeling forces of Examples 1, 2, and 3 were 300, 200, and 100o/15mm, respectively.
The sealability of the package was sufficiently practical, and the ease of opening by hand was good in both cases. On the other hand, the peeling force of Comparative Examples 1, 2, and 3 was 2000.50, respectively.
In Comparative Example 1, in which the sealing layer was made of only ionomer resin, the peeling force was large and it was impossible to open the seal by hand, and the amount of ethylene-propylene copolymer in the sealing layer exceeded the upper limit of the range of the present invention. In the case of Comparative Example 2, the peeling force was too small, and although it was easy to open by hand, it did not have sealing properties, and the inside of the seal layer peeled off, resulting in stringy or bag-like peeling on the peeled surface, which was undesirable.

Furthermore, in Comparative Example 3, in which the sealing layer was made of only ethylene-propylene copolymer, although the seal was easy to open, the peeling force was small and the sealing performance could not be satisfied.

2 L [The outer layer is a saponified ethylene-vinyl acetate copolymer (ethylene 144 mol%, manufactured by Kura 1 Co., Ltd., product name Kovar EP)
), and the 5-layer film was made in the same manner as in Example 2, except that the adhesive layer was an ethylene-vinyl acetate copolymer unsaturated carboxylic acid graft product (manufactured by Mitsui Petrochemicals Co., Ltd., trade name Atomer VF500). and a commercially available stretched polypropylene (2
0μ)/vinylidene chloride copolymer coated cellophane (2
A package (Example 4) was prepared in the same manner as in Example 2 except that a lid material with a thickness of 83 μm having a composition of 3 μm)/ethylene vinyl acetate copolymer (40 μm) was used, and a commercially available lid material was used. Example 2 except that a lid material dry laminated with a polyurethane adhesive having a structure of oriented polypropylene/vinylidene chloride copolymer coated cellophane/polyethylene sealing layer was used.
A package (Example 5) was obtained in the same manner as above. Regarding the seal layers of the packages of Examples 4 and 5, peel force measurements and manual openability tests were conducted in the same manner as in Example 1. As a result, the peeling force of Examples 4 and 5 was 280Q/
15n+w and 2500/ 15+++-,
In all cases, the sealability was sufficiently practical and the ease of opening by hand was also good.

Examples 6-11 Outside II/Adhesive I! / In the structure of the sealing layer, hard vinyl chloride resin was used as the outer layer, the same ethylene-vinyl acetate acid-modified material as in Example 1 was used as the adhesive layer, and the melt index was 0.5 (Example 6). )
, 0.7 (Example 7), 1.2 (Example 8), 2.8 (
Example 9), 5.0 (Example 10), and 12.0 (
Example 11) The same procedure as Example 1 was used, except that a mixed layer was used in which 33.3 parts by weight of the same ethylene-propylene copolymer as in Example 1 was mixed with 100 parts by weight of each o/10in oil-resistant fluoromer. Similarly, by coextrusion, the thickness of the outer layer/adhesive layer/sealing layer was 250μ15μ15.
Each 3-layer film with 0μ was obtained.

The films of Examples 6 to 11 and the vinylidene chloride copolymer coated polyethylene terephthalate outer layer (13μ)/ethylene-vinyl acetate copolymer (contains vinyl acetate @ 5%) seal! (50μ) The sealing layer with the lid material is made by Tester Sangyo. Product name J
130℃, pressure 2 using P-701 type heat sealer
Heat-sealing was performed under the conditions of KQ/cd and sealing time of 2 seconds to prepare peel test evaluation samples. Each sample was then subjected to peel force measurement and easy-openability test in the same manner as in Example 1. As a result, the peeling forces of Examples 6, 7, 8, 9, 10 and 11 were 170, 160, 180, 200,
320. and 600g/15in. As the results show, the films of Examples 6 to 11 all had practical sealing properties and good ease of opening.

Examples 12-14 and Comparative Examples 4-5 In the coextruded three-layer film of Example 8, 3 (Example 12) has an ethylene content within the range of the present invention.

20 (Example 13) and 40 (Example 14) t4ff
Ionomer resin made from 1% ethylene-propylene copolymer (melt index 1.2 g/10 m1n)
A 3M film was obtained in the same manner as in Example 8, except that a sealing layer containing 33.3 parts by weight of each material was used, based on 100 parts by weight. In addition, a three-layer film (Comparative Example 4) was prepared in the same manner as in Example 8 except that the sealing layer was made of polypropylene alone, and the ethylene content of the ethylene-propylene copolymer of the sealing layer was 60% by weight, which is outside the scope of the present invention. A three-layer film (Comparative Example 5) was obtained in the same manner as in Example 8 except that a mixed layer having the same composition as above was used. Regarding the sealing layers of the three-layer films of Examples 12 to 14 and Comparative Examples 4 to 5 obtained, evaluation samples were prepared in the same manner as in Example 8 using the same sealing partner as in Example 8, and the peeling force was measured. and an easy-to-open test. As a result, the peeling forces of Example 12.13.14 and Comparative Examples 4 and 5 were 100.400.510 and 5.
0.500°/15mm, Examples 12, 13 and 14 all have practical sealing properties, good ease of opening, good transparency of the sealing layer of the present invention, and thread in the peeling part. It had a good appearance with no scratches. On the other hand,
Comparative Example 4 has poor sealing properties and unfavorable transparency with a haze value of 10% or more, and Comparative Example 5 has an ethylene content of the ethylene-propylene copolymer in the sealing layer that exceeds the range of the present invention. Although the sealability and ease of opening were good, the transparency of the sealing layer was unfavorable.

33.3ffi1 of ethylene-propylene copolymer with an ethylene content of 5% by weight was added to 100 parts by weight of an ionomer resin with a melt index of 1.2 (+/10 min).
The mixture of parts was mixed with a diameter of 45 mm and an l-/D ratio of 2.
Extrusion molding was performed through an annular die using an extruder No. 8, and inflation was performed to obtain a single layer film with a thickness of 80 μm to be used as a sealing layer of the multilayer packaged dangerous drug of the present invention.

As a seal partner film for evaluating the processed film and easy-open seal, a polyethylene press sheet (Example 15) and an ethylene-vinyl acetate copolymer (vinyl acetate content: 15%) press sheet (Example 16) were used. ), Echi 1
Press sheet of non-ethyl acrylate copolymer (containing ethyl acrylate ffi'15ffi1%) (Example 11), and ionomer resin (manufactured by Mitsui Polychemical Co., Ltd.)
Press sheet of product name Himilan 1eoi (Example 1)
8) each having a thickness of 200μ was produced using a tabletop press machine, and heat-sealed using a heat sealer (trade name: JP-701 type, manufactured by Tester Sangyo) under the same conditions as in Example 6. An easy-to-open seal evaluation sample was obtained by sealing the sealing layer film and the press sheet to which it was sealed. Example 1 for each sample obtained
As a result of measuring peel force and conducting an easy-to-open test in the same manner as above, the peel force of Examples 15, 16, 17 and 18 was 21.
0.20'5.208 and 200 (1/15 mm), both of which have sealing properties and good ease of opening.
It has been found that the sealing layer of the present invention can provide easy-to-open seals to a wide variety of sealing partners.

Claims (1)

[Claims] (1) Melt index is 0.5-100 o/1
A Wi layer consisting of at least one heat-sealing layer formed by mixing 5-65 parts by weight of an ethylene-propylene copolymer having an ethylene content of 1-50% by weight with 100 parts by weight of an ionomer resin having an ethylene content of 1-50% by weight. A multilayer packaging material that can be easily opened and sealed using an olefin resin as a sealing layer.