JPH06924A - Multi-layered oriented film and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain multi-layered oriented film excellent in transparency, gas barrier properties, heat sealing properties and the like by a method wherein polyamide resin layer is made of blend consisting of amorphous nylon and other nylon in multi-layered oriented film containing polyamide resin layer, saturated polyester resin layer and the like. CONSTITUTION:In multi-layered oriented film containing polyamide resin layer A, saturated polyester resin layer B, saponified ethylene-vinyl acetate copolymer resin layer C, modified polyolefin bonding resin layer D and heat sealing resin layer E, layer made of blend consisting of amorphous nylon and other nylon is used. The film is produced by laminating layers in the order of B-D-A-C-A-D- E or B-D-A-D-C-D-A-D-E starting from the outermost layer.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is excellent in pinhole resistance, transparency, gas barrier property, heat sealability, mechanical strength, etc., used as a film for shrink wrapping, pillow wrapping and other food products and other wrapping films. And a method for producing the same.

[0002]

2. Description of the Related Art As a method for tightly packing irregular contents such as foods and sundries, a shrink film such as polyvinyl chloride, polyethylene or polypropylene is used for packing.
A method has been used in which heat is applied to the film for a short time to cause the film to shrink and the packaging material to fit the contents so that the film looks good.

Depending on the contents and the distribution method, it is necessary that these films satisfy a plurality of functions such as mechanical strength and gas barrier property as properties required for these films.
It is conceivable that the film has a laminated structure of several layers and various functions are dispersed in each layer so that the film has many functions as a whole.

For example, in the food industry, the quality is deteriorated due to various alterations such as loss of shape, color, taste and aroma due to temperature, moisture, oxygen, light rays, etc., and microorganisms such as bacteria and mold in the distribution process. Conventionally, a method of directly adding additives such as preservatives and antioxidants to foods has been used as a method of easily storing the product without degrading its quality until it enters the mouth of the consumer. However, in recent years, in the food processing industry, especially livestock meat processing and fish meat processing fields, restrictions on additives to foods have become strict, and the amount of additives used is decreasing or almost not used. In order to secure the properties and freshness, it has become necessary to develop a film in which the packaging material is provided with functionalities such as an oxygen gas barrier property.

Further, in the transportation stage in the food distribution process, the conventional film has a problem in mechanical strength such as generation of pinholes depending on the transportation method.

On the other hand, in recent years, food manufacturers have been moving toward rationalization in terms of both personnel and equipment in the production process, and packaging machines such as pillow-type packaging machines for the purpose of speeding up and automation. Has become popular. Depending on such a packaging machine, since the product flows at a high speed, the time required for heat sealing is naturally shortened, which causes a problem of heat sealing failure. Therefore, as a property required for the packaging material, good heat sealability is a major point, but polyethylene or the like which has been conventionally used as a seal layer in a multilayer film has a drawback that the heat sealability is significantly reduced after stretching. Had.

The present invention uses a polyamide resin layer as a mechanical strength imparting and pinhole resistance improving layer, and a saturated polyester resin layer, and an ethylene-vinyl acetate copolymer saponified resin layer as a gas barrier property imparting layer, Further laminated heat seal resin layer, sequentially biaxially stretched,
Alternatively, it is heat-set after that.
In these laminated films, when the polyamide resin layer or the ethylene-vinyl acetate copolymer saponified resin layer is the outermost layer, the dimensional change due to the humidity in the storage atmosphere and the influence of water during boil sterilization of the package. Also, problems such as whitening of the resin occur. In the present invention, these problems are solved by laminating a saturated polyester resin having a low water absorption coefficient and a low thermal expansion coefficient on the outermost layer.

As a biaxial stretching method for a film, a sequential biaxial stretching method by a tenter system and a simultaneous biaxial stretching method are known. Comparing these two methods, the sequential biaxial stretching method
The structure of the device is simple and the productivity is superior to the simultaneous biaxial stretching method. However, in the conventionally used aliphatic polyamide resins represented by nylon 6 and nylon 6-6, the direction of hydrogen bonding in the longitudinal stretching in the sequential biaxial stretching is the same as the direction of the transverse stretching, so that the transverse stretching is extremely Have difficulty.

As a method of solving these problems, a method of blending an aliphatic polyamide with a polyamide containing a metaxylylene group is described in Japanese Patent Publication No. 51-29193. However, the film obtained by this method is insufficient in transparency and cannot satisfy the requirements as a packaging film. The inflation method is also known as one of the simultaneous biaxial stretching methods, but it is not suitable for stretching a film having a complicated structure as in the present invention.

As a result of intensive studies by the present inventors, the use of a layer made of a blend of amorphous nylon and other nylon as the polyamide layer results in good biaxial stretchability and further pin resistance. It was possible to obtain a multilayer stretched film having excellent hole property, transparency, gas barrier property, heat seal property, mechanical strength and the like and a method for producing the same. A multilayer stretched film containing amorphous nylon as a polyamide layer is described in JP-A No. 64-71749, but the purpose of using amorphous nylon is only to improve the barrier property. The method also
Although it is carried out by the inflation method (tubular method), in the present invention, it is possible to improve the successive biaxial stretchability by the tenter method, and not only the barrier properties but also the pinhole resistance, transparency and mechanical strength as properties. And the like are also used for the purpose of improving them at the same time, which is different from the above invention.

[0011]

The object of the present invention is to have excellent suitability for successive biaxial stretching, and excellent pinhole resistance, transparency, gas barrier property, heat sealability and mechanical strength. Another object of the present invention is to provide a multilayer stretched film and a method for producing the same.

[0012]

The present invention is directed to a polyamide resin layer (A), a saturated polyester resin layer (B), an ethylene-vinyl acetate copolymer saponified resin layer (C), and a modified polyolefin adhesive resin layer ( D), and a multilayer stretched film including a heat seal resin layer (E), wherein the polyamide resin layer (A) is a layer made of a blend of amorphous nylon and other nylon, Film, e.g. from the outermost layer BDAACDAE, BDADACD
-A-D-E, B-D-A-C-D-A-D-E, B-
D-A-D-C-A-D-E, B-D-C-A-C-D
-E, B-D-C-D-A-D-C-D-E, B-D-
C-A-D-C-D-E, B-D-C-D-A-C-D
-E, B-D-A-C-D-E, B-D-A-D-C-
D-E, B-D-C-A-D-E or B-D-C-
The present invention relates to a multilayer stretched film laminated in the order of D-A-D-E and a method for producing the same.

The polyamide resin (A) used in the present invention is a layer composed of a blend of amorphous nylon and other nylon. The amorphous nylon can be obtained by pressure melt polycondensation, decarboxylation condensation reaction and the like using a raw material such as dicarboxylic acid, diamine, lactam, diisocyanate. Examples of the dicarboxylic acid include adipic acid, suberic acid, azelaic acid, terephthalic acid and isophthalic acid. As the diamine, hexamethylenediamine, trimethylhexamethylenediamine, isophoronediamine, bis-p- (aminocyclohexyl) methane, bis-p- (aminocyclohexyl) propane and the like are used. Examples of lactams include caprolactam and laurolactam. As the diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate and the like are used. Other nylons to be blended include nylon 6, nylon 12, nylon 11 and nylon 6-, which are produced by polycondensation reaction of ω-aminocarboxylic acid, polycondensation reaction of dibasic acid and didicarboxylic acid amine, and the like. 6, Nylon 6-10, Nylon 6-12, and copolymers or blends thereof are used.

The saturated polyester resin layer (B) is obtained by condensation of a saturated dibasic acid and glycols, and examples thereof include polyethylene terephthalate (hereinafter abbreviated as PET) and phthalic acid obtained from ethylene glycol and terephthalic acid. , A polyethylene terephthalate copolymer having a saturated dibasic acid such as isophthalic acid, sepacic acid, adipic acid, azelaic acid, glutaric acid, succinic acid, and oxalic acid as a copolymerization component, and a diol component
In addition to a polyethylene terephthalate copolymer containing 4-cyclohexanedimethanol, diethyl glycol, propylene glycol, etc. as a copolymerization component or a blend thereof, polybutylene terephthalate (PBT), poly 1,4-cyclohexylene dimethylene terephthalate,
Polyarylate, poly-p-oxybenzoyl, and copolymers thereof are used.

The saponified ethylene-vinyl acetate copolymer resin (hereinafter abbreviated as EVOH) layer (C) has a softening temperature (flow tester method) of 150 ° C. to 175 ° C. and an ethylene content of 25 to 50 ° C. It is preferably 75 mol% and the degree of saponification with respect to vinyl acetate in the copolymer is 90% or more.

Resin layer for bonding modified polyolefin (D)
Is an ethylene-vinyl acetate copolymer, or ethylene-
Propylene elastomer is chemically treated with monobasic unsaturated fatty acids such as acrylic acid and methacrylic acid, or anhydrides of dibasic unsaturated fatty acids such as maleic acid, fumaric acid and itaconic acid, that is, maleic anhydride. An acid-modified olefin resin obtained by binding is used.

The heat seal resin layer (E) is made of low density polyethylene (LDPE) or linear low density polyethylene (L).
LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polypropylene (PP),
Polyolefin resins such as ethylene-vinyl acetate copolymer (EVA) and ethylene-methyl methacrylate copolymer (hereinafter referred to as EMMA).
Is abbreviated. ), Ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer Resins such as (EAA), ethylene-methacrylic acid copolymer (EMAA), and ionomer (ION) can be used.

The total thickness of the multilayer stretched film of the present invention is 10
The plastic film having a thickness in the range of up to 150 μm is suitable as a packaging film used for applications such as food packaging.

The multilayer stretched film of the present invention comprises BD
-C-A-D-E, B-D-A-D-C-D-A-D-
E, B-D-A-C-D-A-D-E, B-D-A-D
-C-A-D-E, B-D-C-A-C-D-E, B-
D-C-D-A-D-C-D-E, B-D-C-A-D
-C-D-E, B-D-C-D-A-C-D-E, B-
D-A-C-D-E, B-D-A-D-C-D-E, B
-D-C-A-D-E or B-D-C-D-A-D
A laminated structure in which the layers are adjacent to each other in the order of −E is adopted.

An appropriate amount of lubricant may be added to the outermost polyolefin resin layer (B) and the innermost heat seal resin layer (E) in order to improve the mechanical suitability for a packaging machine. .

As a method for producing the multilayer film of the present invention, a method of melt-extruding from a laminating die by a coextrusion method using a plurality of extruders and then cooling and solidifying is most suitable. As a stretching method, a sequential biaxial stretching method by a tenter system is used, and the stretching temperature is preferably 50 ° C. to 200 ° C. and the stretching ratio is 2 to 6 times.
A non-heat-shrinkable multilayer biaxially stretched film can also be obtained by continuously performing heat setting at a temperature higher than the stretching temperature by 5 ° C. or more after stretching.

[0022]

【Example】

[Examples 1 to 3] Table 1 shows Examples and Comparative Examples of the present invention. All the films were melt extruded from a multi-layer coextrusion die by a T-die extrusion method to prepare a film having a thickness of 350 μm.

The film constitution is as follows: polyester resin layer / adhesive resin layer (1) / polyamide resin layer / EVOH
/ Polyamide resin layer / adhesive resin layer (2) / heat seal resin, and the thickness ratio of each layer is 10/7/10/10
/ 10/7/46%.

The polyamide resin layer is Mitsui DuPont Polychemical Sealer PA3426 as amorphous nylon (hereinafter abbreviated as A-Ny) and nylon 6 (abbreviated as 6-Ny) as other nylon to be blended Ube Industries 1030B. As a comparative example, A-Ny and 6-Ny were also used alone.

Other raw materials for each layer constituent resin include polyester resin layer Mitsubishi Rayon DC-003 adhesive resin layer (1) Mitsui Petrochemical Admer NF-
500 EVOH Kuraray Eval E-105
AD adhesive resin layer (2) Tosoh Mersen P2030
W heat seal resin Mitsui DuPont Polychemical Himilan 1601S was used.

The obtained multilayer film was sequentially biaxially stretched by a biaxial stretching experimental device manufactured by Toyo Seiki Seisakusho.
The stretching temperature was 70 to 100 ° C., and the stretching ratio was 2.5 times in each of the length and width. Table 1 shows the suitability for sequential biaxial stretching of each sample.

[0027]

[Table 1]

As shown in Comparative Examples 1 and 2, when A-Ny was used alone and the ratio of A-Ny was 80%, the load during stretching was large and the film broke during the stretching, and the stretching conditions were Even if shaken, no good film was obtained. Also, with regard to 6-Ny alone, stretching unevenness occurred during transverse stretching, and a good film could not be obtained. On the other hand, the films of Examples 1 to 3 according to the present invention could be stretched without any particular problem and good films were obtained.

[Example 4] As a film constitution, a polyester resin layer / adhesive resin layer / EVOH / polyamide resin layer / adhesive resin layer / EEA film was melted from a multi-layer coextrusion die in the same manner as in Example 1. 350μ by extrusion
An m-thick film was prepared. Thickness ratio of each layer is 10/1
It was set to 0/10/15/10/45%.

The polyamide resin layer is made of Amorphous Nylon as Mitsui DuPont Polychemical Sealer PA3426,
50% of Ube Industries 1030B is used as nylon 6.
/ 50% blend.

Other raw materials are polyester resin layer Eastman Kodak KO
DAPAK PET9921 EVOH Kuraray Eval E 105
AD Adhesive resin layer Mitsui Petrochemical Admer VF
-500 EEA Mitsui DuPont Polychemical Evaflex A-701 was used.

The obtained multi-layer film was subjected to a biaxial stretching experiment device to sequentially perform biaxial stretching. The stretching temperature is 65 to 100 ° C., and the stretching ratio is 2 to 2 in both length and width.
It was shaken in a range of 4.5 times and performed under several conditions. The stretchability was good under all conditions.

[Example 5] As a film constitution, a polyester resin layer / adhesive resin layer (1) / EVOH / polyamide resin layer / adhesive resin layer (2) / ION film (Example 5) and EVOH / A polyamide resin layer / adhesive resin layer (2) / ION film (Comparative Example 4) was melt extruded from a multi-layer coextrusion die in the same manner as in Example 1 to prepare a film having a thickness of 450 μm. The thickness ratio of each layer is 10/10/10/10/1 for the film of Example 5.
5/45% and the film of Comparative Example 4 was 10/25/10
/ 55%.

The polyamide resin layer is made of Mitsui DuPont Polychemical Sealer PA3426 as amorphous nylon.
A blend of Ube Industries 1030B was used as 6-Ny, and a blend ratio of 50% / 50% was used.

Other raw materials are polyester resin layer Mitsubishi Rayon DC-003 adhesive resin layer (1) Mitsui Petrochemical Admer NF
-500 EVOH Kuraray Eval E-105
AD adhesive resin layer (2) Tosoh Mersen P2030
W ionomer resin layer Mitsui DuPont Polychemical Himilan 1601S.

The above film is sequentially subjected to a biaxial stretching machine,
The film was longitudinally stretched 3 times at 85 ° C. and then laterally stretched 3 times at 90 ° C. to prepare a stretched film having a thickness of 50 μm. A package was prepared using the obtained film, and sterilized by boiling in boiling water at 100 ° C. for 20 minutes. Example 5 in this step
The film using No. 2 had no particular problem, but the film using Comparative Example 4 had the EVOH layer whitened.

[Example 6] As a film constitution, a film of polyester resin layer / adhesive resin layer / EVOH / polyamide resin layer / EVOH / adhesive resin layer / EEA was used in the same manner as in Example 1 in a multi-layer coextrusion die. Was melt-extruded to prepare a film having a thickness of 350 μm. The thickness ratio of each layer was 10/10/10/15/10/10/35%.

The polyamide resin layer is A-Ny / 6-Ny.
(Blend ratio = 50% / 50%), and as a comparative example, nylon MXD6 (Mitsubishi Gas Chemical MX nylon 6)
580) and 6-Ny (Ube Industries 1030B) (blend ratio = 70% / 30%), and 6.6
6 copolymer nylon (Ube Industries 5033B) was used.

Other raw materials are polyester resin layer Eastman Kodak K
ODAPAK PET 9921 EVOH Kuraray Eval F Adhesive resin layer Mitsui Petrochemical Admer V
F-500 EEA Mitsui DuPont Polychemical Evaflex A-701 was used.

The obtained multi-layer film was subjected to a biaxial stretching experiment device to sequentially perform biaxial stretching. The stretching temperature was 75 ° C., and the stretching ratio was 2.5 times in each of the length and width. The light transmittance and the haze of the obtained multilayer biaxially stretched film were measured by the ASTM D-1003 method, and the results shown in Table 2 were obtained.

The film of the invention had very good transparency as compared with the film of the comparative example. The oxygen permeability of the film of Example 6 (thickness after stretching = 50 μm) and the film of the same configuration before stretching (thickness of 50 μm by drawing) (Comparative Example 7) were measured by the oxytran method (20 ° C., 65% R).
H).

[0042]

[Table 3]

As shown in Table 3, the oxygen gas barrier property after stretching is greatly improved.

[0044]

INDUSTRIAL APPLICABILITY The multilayer stretched film according to the present invention has excellent suitability for successive biaxial stretching and also has excellent physical properties such as pinhole resistance, transparency, gas barrier property, heat sealability and mechanical strength. Therefore, it is suitable as a film for foods and other packaging.

[Table 2]

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 17, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

An appropriate amount of a lubricant may be added to the outermost saturated polyester resin layer (B) and the innermost heat seal resin layer (E) in order to improve mechanical suitability for a packaging machine. .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of items to be corrected] Table 2

[Correction method] Change

[Correction content]

[Table 2] ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 5, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

An appropriate amount of a lubricant may be added to the outermost saturated polyester resin layer (B) and the innermost heat seal resin layer (E) in order to improve mechanical suitability for a packaging machine. .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0040

[Correction method] Change

[Correction content]

The obtained multi-layer film was subjected to a biaxial stretching experiment device to sequentially perform biaxial stretching. The stretching temperature is 7
The stretching ratio was 5 ° C. and the stretching ratio was 2.5 times in each of the length and width. The light transmittance and haze of the obtained multilayer biaxially stretched film were measured by the ASTM D-1003 method, and the results shown in Table 2 were obtained.

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Claims (3)

[Claims] 1. A polyamide resin layer (A), a saturated polyester resin layer (B), an ethylene-vinyl acetate copolymer saponified resin layer (C), a modified polyolefin adhesive resin layer (D) and a heat seal resin layer ( A multilayer stretched film containing E), wherein the polyamide resin layer (A) is a layer made of a blend of amorphous nylon and other nylons. 2. A multi-layer stretched film is provided from the outermost layer of BD-A-C-A-D-E, B-D-A-D-C-D-D-D-E, B-D-A. -C-D-A-D-E, B-D-A-D-C-A-D-E, B-D-C-A-C-D-E, B-D-C-D-A -D-C-D-E, B-D-C-A-D-C-D-E, B-D-C-D-A-C-D-E, B-D-A-C-D -E, B-D-A-D-C-D-D, B-D-C-A-D-E or B-D-C-D-A-D-E The multilayer stretched film according to claim 1. 3. The method for producing a multilayer stretched film according to claim 1, wherein the stretching temperature is 50 to 200 ° C. and the stretching ratio is 2 to 6 times, and the biaxial stretching is successively performed.