JP2005028863A - Coextruded laminated film for deep drawing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coextruded laminated film for deep drawing which shows characteristics wherein, when a content is housed in a bottom material obtained by deep drawing and is sealed with a lid material or a packaged item is stored, a flange portion of the packaged item is not curled toward the content, the fitness of the film to the content is not damaged, no wrinkles are generated in the bottom material of the packaged item, and further to three or four packaged items are smoothly fixed in series with a tape. <P>SOLUTION: The coextruded laminated film for deep drawing comprises an outer layer (A) made of an amorphous polyester resin, an adhesive layer (B), a polyamide resin layer (C), a saponified ethylene-vinyl acetate copolymer resin layer (D), an adhesive layer (E), and an inner layer (F) made of a polyolefin resin, wherein the thickness of all layers is 50 to 150μm, a ratio of the thickness of the outer layer (A) to that of all layers is 30 to 60%, and an oxygen permeation degree is not more than 50cm<SP>3</SP>/m<SP>2</SP>×day×atm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a co-extrusion laminated film for deep drawing having a specific thickness and having an oxygen gas barrier property comprising an outer layer of an amorphous polyester resin having a specific thickness and each layer made of the specific resin.

2. Description of the Related Art Vacuum packaging in which contents are stored in a bottom material of a laminated film obtained by deep drawing and then a lid is sealed and vacuum deaerated is widely used for packaging such as sliced ham. As a packaging material used for such packaging, a laminated film including an oxygen gas barrier layer is used.
In Patent Document 1, a heat-sealable resin layer is formed as the innermost layer, and an outermost layer opposite thereto is formed from an amorphous polyester resin layer, and a polyamide resin layer or a polyamide resin layer and a saponified ethylene vinyl acetate copolymer layer are formed as an intermediate layer. A barrier resin layer, and a polyolefin adhesive resin layer between the outermost layer and the intermediate layer and between the heat sealable resin layer and the intermediate layer, and the thickness of the amorphous polyester resin layer is composite. A coextruded composite film for deep drawing is described which is in the range of 4-18% of the total thickness of the film.

Patent Document 2 discloses an outer layer (A) made of a resin selected from a polyamide-based resin and a polyester-based resin, an intermediate layer (B) including at least a polyamide-based resin layer, and an outer layer (C) having heat sealing properties. An aliphatic polyamide resin having a saturated water absorption of less than 5%, a composition containing the polyamide resin, and a polyester resin, the outer layer (A) being on the surface layer side Is a polyester resin selected from a (co) polymer of a diol component having 3 or more carbon atoms in a hydrocarbon and a dicarboxylic acid component, and the outer layer (C) is a heat seal layer (C1) disposed on the surface layer side And the melting point of the resin forming the heat seal layer (C1) is lower than the melting point of the resin forming the inner layer (C2). Multilayer film for drawing is described.
The deep drawing laminated film is usually used as a bottom material. In the base material formed by deep drawing the laminated film described in Patent Document 1 and Patent Document 2, the contents are stored and the lid material is sealed and vacuum degassed to form a package, or the package is There is a need for a packaging material that does not curl because the flange portion of the package may curl toward the contents during storage.

In Patent Document 3, a rigid resin layer having a tensile modulus of 120 to 400 kg / mm ² , a moisture absorption rate of 0.4% or less, and a layer thickness of 5 to 40% of the total thickness is defined as the outermost layer. A composite film having an anti-curl effect is disclosed. When this thickness ratio is too large (over 40%), it is described that the fit of the composite film to the contents in the case of a package is poor.
On the other hand, when the package is filled with the package, and the package after being molded integrally with the lid is sent to an automatic aligner, and the final product is fixed with three or four packages with adhesive tape There is also. At this time, if the flange portion of the package is soft or curled, the package will not be neatly aligned in the automatic aligning machine, and therefore it will be difficult to fix with the adhesive tape.

Japanese Patent No. 3051614 (Claim 1, page 2, right orchid 1st to 5th lines) JP 2002-178470 A (Claim 1) JP-A-58-39443 (Claim 1, page 2, upper right orchid 1st to 3rd lines)

  The object of the present invention is to store the contents in the bottom material obtained by deep drawing and seal the lid material and / or when storing the packaging body, the flange portion of the packaging body (of the lid material and the bottom material). Providing a co-extrusion laminated film for deep-draw molding without curling the inner layer surfaces), and the fit of the film to the contents is not impaired. Alternatively, it is to provide a co-extrusion laminated film for deep drawing in which the operation of fixing four pieces in series with an adhesive tape is smoothly performed.

  As a result of intensive studies for solving the above problems, the present inventors have found that an outer layer (A) composed of an amorphous polyester resin layer, an adhesive resin layer (B), a polyamide resin layer (C), ethylene vinyl acetate copolymer Identifies the thickness range of all layers and the thickness ratio of the outer layer (A) of the coextruded laminated film for deep drawing formed of the coalescence saponified resin layer (D), adhesive resin layer (E), and inner layer (F) made of polyolefin resin By setting the range, the curling is not generated, the fit of the film to the contents is not impaired, and the operation of fixing three or four packages with a series of adhesive tapes is performed smoothly. The present inventors have found that a laminated film for drawing can be obtained, and have completed the present invention.

That is, the first of the present invention is an outer layer (A) made of an amorphous polyester resin, an adhesive resin layer (B), a polyamide resin layer (C), an ethylene vinyl acetate copolymer saponified resin layer (D), and an adhesive resin. The layer (E) is composed of an inner layer (F) made of a polyolefin resin, the thickness of all layers is 50 to 150 μm, the thickness ratio of the outer layer (A) is more than 40% and not more than 60% of the thickness of all layers, and oxygen Provided is a co-extrusion laminated film for deep drawing, which has a permeability of 50 cm ³ / m ² · day · atm or less.
The second of the present invention is, in order, an outer layer (A), an adhesive resin layer (B), an ethylene vinyl acetate copolymer saponified resin layer (D), a polyamide resin layer (C), an adhesive resin layer (E), and an inner layer. The layer order of (F) is taken, and the coextruded laminated film for deep drawing according to the first invention is provided.
3rd of this invention consists of two layers from which the inner layer (F) contacts the to-be packaged object (F1) and the layer (F2) which does not contact to to-be-packaged goods, and the thickness of a layer (F1) is 2-20 micrometers. The coextruded laminated film for deep drawing according to the first or second invention is characterized by being in a range.
According to a fourth aspect of the present invention, there is provided the coextrusion laminated film for deep drawing according to the third aspect, wherein the layer (F1) is an easy peel resin layer.
5th of this invention provides the coextrusion laminated film for deep drawing of the said 1st-4th invention, wherein the thickness of an outer layer (A) is 30-85 micrometers.

  When packaging sliced ham and the like by vacuum packaging, the coextruded laminated film for deep drawing according to the present invention is used as a bottom material, so that the curled state of the flange portion of the package and the fit of the film to the contents can be achieved. It is possible to obtain a package that is not damaged and can smoothly perform the operation of fixing three or four packages in a series with an adhesive tape.

Hereinafter, the present invention will be described in detail.
The present invention provides a deep drawing by setting the thickness ratio of the amorphous polyester resin used for the outer layer (A) constituting the coextrusion laminated film for deep drawing to a specific range with respect to the thickness of all layers. A packaging material that does not cause problems due to curling when the contents are stored in a vacuum packaging body using a bottom material molded from a coextruded laminated film and a lid prepared separately. provide.
The amorphous polyester resin used for the outer layer (A) constituting the laminated film of the present invention is not particularly limited as long as the melting point is not observed by thermal analysis such as DSC (differential thermal scanning calorimeter). A typical example is PET-G6763 manufactured by Eastman Chemical Co., Ltd.
The thickness of the amorphous polyester is more than 40% and 60% or less, preferably 41% or more and 60% or less, most preferably 41% or more and 55% or less of the total thickness. The thickness of the outer layer (A) made of an amorphous polyester resin is preferably 30 to 85 μm, more preferably 35 to 70 μm. When the thickness of the outer layer (A) made of an amorphous polyester resin is within the range defined by the present invention, curling is unlikely to occur when a package is formed, the film fit to the contents can be maintained, and gas barrier properties The performance as a laminated film such as strength is also maintained. Amorphous polyester is advantageous in that whitening of the polyester film surface due to drawing heat molding, heat sterilization, etc. can be suppressed, and dimensional stability of the film can be obtained.

  Resins used for the adhesive resin layers (B) and (E) are various basic polyolefins such as monobasic unsaturated fatty acids such as acrylic acid and methacrylic acid, dibasic unsaturated fatty acids such as maleic acid, fumaric acid and itaconic acid. Or grafted with these anhydrides, such as maleic acid grafted EVA, maleic acid grafted ethylene-α-olefin copolymer, or ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer Copolymers (EAA), ethylene-methacrylic acid copolymers (EMAA), ethylene-ethyl acrylate copolymers (EEA) and other ethylene copolymers and maleic anhydride copolymers, polyethylene (PE) and maleic anhydride copolymers A polymer etc. can be mentioned. The thickness of the adhesive layer is preferably 1 to 10 μm.

As the polyamide used for the polyamide layer (C), nylon 6, nylon 66, nylon 6-66, nylon 6-12, nylon 6T-6I and the like are preferably used. As for the thickness of a polyamide layer (C), 5-20 are preferable.
The resin used for the ethylene-vinyl acetate copolymer saponified resin (abbreviation, EVOH) layer (D) preferably has an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more. The thickness of the EVOH layer (D) is preferably 5 to 25 μm.

  The inner layer (F) is made of a polyolefin resin. Examples of polyolefin resins include linear low density polyethylene (SSC-LLDPE) polymerized using a single site catalyst (hereinafter abbreviated as “SSC”), and linear ultra low density polymerized using SSC. Polyethylene (PE) such as polyethylene (SSC-VLDPE), conventional LDPE (low density polyethylene), VLDPE (very low density polyethylene), LLDPE (linear low density polyethylene), ethylene such as EVA, EAA, EMAA, EEA Mention may be made of polypropylene copolymers such as polypropylene copolymers, ionomer resins, polypropylene (PP), propylene-ethylene copolymers and propylene-butene copolymers. The thickness of the heat seal layer is preferably 10 to 100 μm.

  The inner layer (F) may be a single layer or a plurality of layers. The layer in contact with the inner layer (F) to be packaged preferably has heat sealability. When the inner layer (F) is composed of a plurality of layers, the inner layer (F) may be composed of a layer (F1) in contact with the package and a layer (F2) not in contact with the package. In the case of a plurality of layers, the layer (F1) in contact with the package is preferably selected from easy peel resins. The easy peel resin is composed of a polymer blend of various polyolefin copolymers, for example, a mixed resin of EVA and PP resin and PE-MAH (maleic anhydride grafted polyethylene), EMAA, PP and PE-MAH. When a resin selected from mixed resins is used, when the lid material and the bottom material easy peel layer are heat-sealed, the lid material and the bottom material film are peeled off and then aggregated at the inner layer (F) of the bottom material (F1) Breaks and exhibits easy peelability (easy peelability). The thickness of the layer (F1) is preferably 2 to 20 μm. The layer (F2) not in contact with the package is a layer for reinforcing the layer (F1) and the entire layer, and is appropriately selected from the above polyolefin resins. The thickness of the layer (F2) is preferably 8 to 98 μm.

The laminated film of the present invention is produced by a known method. The production of an unstretched laminated film by the T-die method is illustrated. Each resin is melt-kneaded by a separate extruder, and a molten parison having a laminated structure is formed at a resin temperature of 200 to 260 ° C. by T-die coextrusion. Next, the draft ratio is set so that the parison has a specified thickness, quenched on a chill roll of 20 to 60 ° C., and drafted to obtain an unstretched laminated film. The layer structure is as follows: outer layer (A) / adhesive resin layer (B) / polyamide resin layer (C) / EVOH layer (D) / adhesive resin layer (E) / polyolefin resin inner layer (F), or outer layer ( The layer order of A) / adhesive resin layer (B) / EVOH layer (D) / polyamide resin layer (C) / adhesive resin layer (E) / inner layer (F) of polyolefin resin can be taken. When the inner layer (F) is composed of the layer (F1) in contact with the package and the layer (F2) in contact therewith, the inner layer (F) is in the order of layer (F2) / layer (F1) in the above layer order. The layer structure is replaced. In this case, the layer (F1) is an easy peel resin layer.
Each resin constituting the outer layer, the polyamide layer, the EVOH layer, the adhesive layer, the heat seal layer, or the easy peel layer has various additives as necessary as long as the desired properties of the present invention are not impaired. Organic or inorganic lubricants, stabilizers and the like may be added.

The thus obtained laminated film has an oxygen permeability at 30 ° C. and a relative humidity (RH) of 80% of 50 cm ³ / m ² · day · atm or less, preferably 40 cm ³ / m ² · day · atm or less. More preferably, it is 30 cm ³ / m ² · day · atm or less. The moisture permeability is preferably 20 g / m ² · day or less, more preferably 15 g / m ² · day or less at 40 ° C. and 90% relative humidity.

  The total thickness of the laminated film is 50 to 150 μm, preferably 60 to 130 μm, more preferably 70 to 110 μm, and particularly preferably 75 to 100 μm. When the thickness of all layers exceeds 150 μm, when the laminated film is filled with the contents after deep drawing, and the packaging material integrated with the lid is molded and heat treated, vertical wrinkles occur on the side of the bottom material. The appearance deteriorates and the thickness of all layers increases, so that the film becomes hard and the fit between the contents and the film deteriorates. When the thickness of all layers is less than 50 μm, the strength of the entire film is reduced, pinholes are generated in the deep drawing process, curls are generated in the package flange, and three or four packages are used. There is a problem that it becomes difficult to work with the adhesive tape as a series. Therefore, when the total thickness is in the above range, curling is difficult, the fit with the contents is good, and further, gas barrier properties and pinhole resistance can be satisfied.

(Example)
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The sample was evaluated by the following method.
Curling evaluation: Using a deep drawing machine (Multivac, Mulch A422 type), formed into a diameter of 95 mm and a depth of 5 mm at a drawing temperature of 85 ° C., filled with pork slice ham having a diameter of 90 mm and a weight of 43 to 47 g. The lid film and vacuum were degassed at a seal temperature of 127 ° C., followed by heat sealing to obtain a ham-filled package. The obtained package is stored in a refrigerator at 5 ° C., and the state of curling of the flange portion is observed. If the displacement from the flat (flat) state is within 5 mm, the curled state is ○, and the displacement is 5 mm. When it exceeded, the curl state was made into x.
Fit: The case where the contents of the ham-filled package were not deformed with the naked eye on the contact surface with the bottom material film as compared with the shape before filling was marked with ◯, and the case where it was recognized with x.
Automatic alignment: When the ham-filled package is put on an automatic alignment machine, when the operation of connecting 4 packages in series with adhesive tape is performed 100 times, ○ is when there are no mistakes, and there is one or more mistakes The case was marked with x.
Ham storage: Store the ham-filled package in a refrigerator at 5 ° C for 2 weeks, check the discoloration of the ham, the occurrence of netting (occurrence of stickiness), and the presence or absence of a bad odor. X.
Oxygen permeability: According to ASTM D3985-81, OX-TRAN 2/20 type manufactured by Modern Control Co. was used and measured at 30 ° C. and 80% RH unless otherwise specified.
Moisture permeability: Measured under the conditions of 40 ° C. and 90% RH according to ASTM F372-73, using Modern Control Co., Ltd., PERMATRAN-W3 / 31 type, unless otherwise specified.

(Example 1)
A multilayer film having a seven-layer structure was formed using the following six types of resin materials.
(1) (A) is an outer layer (hereinafter referred to as a PET layer) of an amorphous polyester resin (PET-G6733 manufactured by Eastman Chemical Co.).
(2) (B) and (E) are maleic anhydride-modified polyolefin (Mitsubishi Chemical Corporation, brand name, modic, MI (melt index): 9 g / 100 min / 10 min), (abbreviation, PO-MAH) Adhesive resin layer.
(3) (C) is a 6-66 nylon resin layer (manufactured by Toray Industries, Inc., brand name, Amilan CM6001FS).
(4) (D) is a layer of ethylene vinyl acetate copolymer saponified resin (Nihon Gosei Co., Ltd., Soarnol A4412B) (abbreviation, EVOH).
(5) (F2) is a layer of ethylene vinyl acetate copolymer resin (vinyl acetate content: 6% by weight, MI: 6 g / 10 min), (abbreviation, EVA).
(6) (F1) is an ethylene / methacrylic acid copolymer resin (methacrylic acid (MAA) content: 9 wt%, MFR: 3 dg / min, density: 0.93 g / cm ³ ) (abbreviation: EMAA) 70 wt. Resin layer (easy peel sealant layer) consisting of 100 parts by weight of 100% by weight of polypropylene resin and 30 parts by weight of polypropylene resin and 6 parts by weight of PO-MAH.
(7) (F) is EVA (Nihon Unicar Co., Ltd., brand: NUC3660, vinyl acetate content: 5-7%, MI: 6 g / 10 min).

By a conventional T-die method, co-extrusion was performed at a resin temperature of 240 ° C. to obtain a laminated film having a width of 1 m and a thickness of 81 μm. The thickness of each layer is (A) / (B) / (C) / (D) / (E) / (F2) / (F1) = 35/5/7/11/5/14/4 (μm) (Total layer thickness: 81 μm, PET layer thickness ratio 43%). The laminated film had an oxygen permeability of 20 cm ³ / m ² · day · atm. The moisture permeability was 12 g / m ² · day. This laminated film was used as a bottom material.
Separately, as a laminated film for a lid, an outer layer OPP (stretched polypropylene) film (thickness: 20 μm), a silica-deposited PET (polyethylene terephthalate) film (thickness: 12 μm) gas barrier layer, LLDPE (linear low density polyethylene) Each layer of the sealing layer of the film (thickness: 40 μm) was bonded by a conventional dry lamination using a polyurethane adhesive to obtain a laminated film.
The obtained bottom material and lid material film were molded into a diameter of 95 mm and a depth of 5 mm at a drawing temperature of 85 ° C. using a deep drawing machine (Multivac, manufactured by Multivac A422), a diameter of 90 mm, and a weight of 43 to 47 g. The pork sliced ham was filled and vacuum-deaerated with the lid film at a seal temperature of 127 ° C., followed by heat sealing to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

(Example 2)
The thickness of each layer is (A) / (B) / (C) / (D) / (E) / (F2) / (F1) = the same as in Example 1 except that the thickness of each layer was changed. A laminated film of 78/6/8/12/6/15/5 (μm) (total thickness: 130 μm, PET layer thickness ratio 60%) was obtained. The oxygen permeability of this laminated film was 19 cm ³ / m ² · day · atm, and the moisture permeability was 10 g / m ² · day. The laminated film was used as a bottom material, and the same lid material as that used in Example 1 was used to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

(Example 3)
The thickness of each layer was (A) / (B) / (C) / (D) / (E) / (F) = 35/3 / in the same manner as in Example 1 except that the thickness of each layer was changed. A laminated film of 5/7/3/6 (μm) (total thickness: 59 μm, PET layer thickness ratio 58%) was obtained. However, the layer (F) was a heat seal layer made of VLDPE. The laminated film had an oxygen permeability of 31 cm ³ / m ² · day · atm, and a moisture permeability of 13 g / m ² · day. The laminated film was used as a bottom material, and the same lid material as that used in Example 1 was used to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

(Comparative Example 1)
The thickness of each layer was changed to (A) / (B) / (C) / (D) / (E) / (F2) / (F1) = the same as in Example 1 except that the thickness of each layer was changed. A laminated film of 65/11/15/23/11/29/8 (μm) and (total thickness: 162 μm) was obtained. The tensile modulus of (A) was 176 Kg / mm ² and the moisture absorption rate was 0.1%. The laminated film had an oxygen permeability of 9 cm ³ / m ² · day · atm, and a moisture permeability of 8 g / m ² · day. The laminated film was used as a bottom material, and the same lid material as that used in Example 1 was used to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

(Comparative Example 2)
The thickness of each layer was changed to (A) / (B) / (C) / (D) / (E) / (F2) / (F1) = the same as in Example 1 except that the thickness of each layer was changed. A laminated film of 52/3/4/5/3/11/2 (μm) (total thickness 81 μm, PET layer thickness 65%) was obtained. The laminated film had an oxygen permeability of 43 cm ³ / m ² · day · atm, and a moisture permeability of 15 g / m ² · day. The laminated film was used as a bottom material, and the same lid material as that used in Example 1 was used to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

(Comparative Example 3)
The thickness of each layer was changed to (A) / (B) / (C) / (D) / (E) / (F2) / (F1) = the same as in Example 1 except that the thickness of each layer was changed. A laminated film of 15/8/10/16/8/19/5 (μm) (total thickness 81 μm, PET layer thickness 18%) was obtained. The laminated film had an oxygen permeability of 15 cm ³ / m ² · day · atm, and a moisture permeability of 10 g / m ² · day. The laminated film was used as a bottom material, and the same lid material as that used in Example 1 was used to obtain a ham-filled package. Table 1 shows the results of evaluating the physical properties of the package.

Claims (5)

From an outer layer (A) made of an amorphous polyester resin, an adhesive resin layer (B), a polyamide resin layer (C), an ethylene vinyl acetate copolymer saponified resin layer (D), an adhesive resin layer (E), and a polyolefin resin The thickness of the entire layer is 50 to 150 μm, the thickness ratio of the outer layer (A) is more than 40% and not more than 60% of the thickness of the entire layer, and the oxygen permeability is 50 cm ³ / m ^2. A coextruded laminated film for deep drawing, characterized in that it is not more than day · atm.   In order, the outer layer (A), the adhesive resin layer (B), the ethylene vinyl acetate copolymer saponified resin layer (D), the polyamide resin layer (C), the adhesive resin layer (E), and the inner layer (F). The coextruded laminated film for deep drawing according to claim 1, wherein   The inner layer (F) consists of two different layers, the layer (F1) in contact with the package and the layer (F2) not in contact with the package, and the thickness of the layer (F1) is in the range of 2 to 20 μm. The coextruded laminated film for deep drawing according to claim 1 or 2.   The coextrusion laminated film for deep drawing according to claim 3, wherein the layer (F1) is an easy peel resin layer.   The thickness of an outer layer (A) is 30-85 micrometers, The coextrusion laminated film for deep drawing in any one of Claims 1-4 characterized by the above-mentioned.