JP2018012201A - Coextrusion multilayer film for deep-drawn package, and bottom material for deep-drawn package and deep-drawn package using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging material and a packaging body having high rigidity and curl resistance as a deep-drawn package without impairing transparency and gloss even after undergoing a heat sealing process. A polybutylene terephthalate resin layer, a polyethylene terephthalate resin layer, a gas barrier layer, and an easy peel layer are provided in this order, and the ratio of the polyethylene terephthalate resin layer thickness to the total film thickness is 30% or more and less than 75%. A co-extruded non-stretched film for deep-drawing packages, and bottom materials and deep-drawing packages for deep-drawing packages using the same. [Selection diagram] None

Description

  The present invention relates to a film for deep-drawn packaging that can be suitably used for packaging mainly sliced ham and slice bacon, and a bottom material for deep-drawn packaging and a deep-drawn packaging using the film.

  In recent years, in the food industry, the reduction of waste due to environmental problems and the reduction in the amount of individual food products have been promoted rapidly along with the deep awareness of consumers, and even in deep-drawn packages such as sliced ham and sliced bacon, packaging There is a demand for a reduction in packaging material, that is, a reduction in thickness, which is nearly halved while maintaining the quality of the material.

In the process of manufacturing deep-drawn packages such as sliced ham and sliced bacon, the film is supplied to a deep-drawing machine and molded into the desired shape and size using a mold, and the contents such as sliced ham are placed in the deep-drawn part. , And heat-sealing and vacuum packaging using the lid material film supplied from above. Then, it cools and a film cut is carried out between each deep drawing part, and each deep drawing package is produced.
Furthermore, in these package applications, in accordance with the reduction of food per individual package, after producing each deep-drawn package, 3 to 4 packages were shifted and overlapped and bonded with a label tape to integrate them. Quad pack production is in progress.

  In such a manufacturing process, if the packaging material film is thinned in accordance with the market demand, the rigidity (waist) of the film is lowered, or curling occurs due to heat sealing with the lid material. These problems of strength and deformation of individual packages not only lower the product value, including appearance, but also significantly deteriorate film production, alignment transportation of individual packages and orderly labeling at the manufacturing stage. To stop.

Conventionally, as a film for deep-drawn packaging, a polyester resin layer is used for the outer layer, a gas barrier layer made of nylon resin (Ny) or ethylene-vinyl acetate copolymer saponified product (EVOH) is used for the intermediate layer, and a polyolefin resin is used for the inner sealing layer. Multi-layer films having layers are widely used in general (for example, Patent Documents 1 to 4).
In these disclosed technologies, an amorphous polyester resin layer obtained by copolymerization with cyclohexanedimethanol or copolymerization with isophthalic acid, or an amorphous amorphous polyester solidified in an amorphous state, is formed on an outer single layer polyester resin layer. By using the polyester resin layer, the waist, gloss, and transparency necessary for the deep-drawn package are provided.

However, since the amorphous polyester resin layer and the amorphous polyester resin layer have a heat deformation temperature (0.455 MPa · ° C.) of less than 100 ° C., the amorphous polyester resin layer and the amorphous polyester resin layer are softened by heat transfer in a heat sealing process for producing a package. Therefore, the malfunction that the external appearance of a film deteriorates arises.
The specific situation of the heat-seal process for producing a deep-drawn package is that the lid and the flange of the deep-drawn bottom material are combined, and in the order of hot plate / lid / bottom material flange / rubber packing In a state where they are in contact and overlapped, heat sealing is performed by heat from a hot plate installed on the upper side of the lid material.
In the case of the prior arts such as Patent Documents 1 to 4, since the outer polyester resin layer is strongly attached to the rubber packing by heat, the polyester resin of the bottom film outer layer is removed when the package is separated from the rubber packing. Deterioration of the appearance such as a roughened layer surface and loss of gloss was a problem.

In addition, the multilayer films of Patent Documents 1 to 3 all have a total thickness of 120 μm or more, so that the film has a waist. Will collapse.
The multilayer film of Patent Document 4 has a total film thickness of 50 to 150 μm, the ratio of the amorphous polyester resin layer thickness of the outer layer to the total film thickness is 40 to 60%, lacks rigidity, and curls are generated by heat sealing. End up.

As a deep-drawn packaging film, a technique in which two types and two layers of polyester resin layers are arranged on the outer layer is also disclosed (for example, Patent Documents 5 to 7).
However, Patent Documents 5 to 6 are techniques for achieving film production with a total film thickness of 300 μm or more, which is as thick as 200 μm to 500 μm only in the outer layer. These have a polyester resin layer thickness of 80% or more of the total film thickness in order to obtain the rigid properties required for gas pack applications in which an inert gas is sealed together with the contents. It is difficult to form a thin film into a film from the viewpoint of processing technology, and it cannot be applied to the use of the present invention which is thin and requires barrier properties and pinhole resistance.
Patent Document 7 is only an example in which the support resin layer having the container heat resistance, the container shape retention property, and the container processing moldability is 300 μm thick, and it is difficult to reduce the thickness of the support resin layer and use it for the deep drawn package. is there. In addition, since it is an outer layer consisting of a mixture of terephthalic acid, ethylene glycol and 1,4-cyclohexanedimethanol ternary copolymer resin and polybutylene terephthalate, the ternary copolymer resin layer is an outer layer. Even if it is changed, it is presumed that curling occurs due to heat sealing as in the case of the outer layer made of a single layer of amorphous polyester resin.

JP 7-096582 A Japanese Patent Laid-Open No. 8-281892 JP 2003-136648 A JP 2005-28863 A JP-A-10-1003006 Japanese Patent Laid-Open No. 10-034852 JP 2000-351186 A

  The present invention is intended to solve the above problems, and a packaging material and packaging body having high rigidity and curl resistance as a deep-drawing packaging body without losing transparency and gloss even after a heat sealing process. It is to provide.

As a result of intensive studies to solve the above problems, it has been found that the above problems can be solved by adopting a specific configuration, and the present invention has been completed.
That is, a deep-drawn package having a polybutylene terephthalate resin layer, a polyethylene terephthalate resin layer, a gas barrier layer, and an easy peel layer in this order, and the ratio of the polyethylene terephthalate resin layer thickness to the total film thickness being 30% or more and less than 75% Coextruded unstretched film.

According to the co-extruded multilayer film for deep-drawn molded article of the present invention, the transparency and gloss are not impaired, it is stiff and curling is difficult, and the outer layer does not adhere to the device contact part during heat sealing, and the appearance is good A film for deep drawing and a package can be provided.
In particular, when thinning the film to reduce the amount of packaging material, the heat of the hot plate is more easily transferred due to the thinness of the film, and the adhesion between the outer surface of the bottom material and the rubber packing of the device is likely to increase. However, according to the film of the present invention, the surface of the outer layer of the film hardly occurs and whitening is suppressed.

Although the film of this invention is demonstrated in detail below, it is not limited to embodiment described below.
In the description, the “outer layer” of the film is a layer that becomes the outer side of the package when formed into a deep-drawn package, the “inner layer” is the layer that becomes the container side, and the “middle layer” is the outer layer. It is a layer located between inner layers.
The film of the present invention has a polybutylene terephthalate resin layer, a polyethylene terephthalate resin layer, a gas barrier layer, and an easy peel layer in this order. Outer layer 1: polybutylene terephthalate resin layer, outer layer 2: polyethylene terephthalate resin layer, intermediate layer: The gas barrier layer and the inner layer will be described below as an easy peel layer.

<Outer layer 1: Polybutylene terephthalate resin (PBT) layer>
A polybutylene terephthalate homopolymer and / or a polybutylene terephthalate copolymer is used for the outer layer 1 located on the surface layer on one side of the film of the present invention. Hereinafter, it may be abbreviated as a PBT layer.
The homopolymer is polymerized using terephthalic acid as the dicarboxylic acid component and 1,4-butanediol as the diol component. Examples of the copolymer include those using dodecanedioic acid or polytetramethylene glycol as the dicarboxylic acid component and tetramethylene oxide glycol as the diol component.

The melting point of PBT is about 220 to 230 ° C., which is lower than that of polyethylene terephthalate (PET). However, PBT has a heat deformation temperature (0.455 MPa) of about 130 to 150 ° C., which is higher than that of PET and has excellent heat resistance. Polyester resins have properties that heat resistance, strength, and rigidity are increased by stretching, but PBT has a higher crystallization speed than PET and has excellent heat resistance and rigidity without stretching.
These are considered to be the main factors for preventing surface roughening and deterioration of gloss and transparency in the heat sealing process when a PBT layer is disposed on the outer layer of the coextruded unstretched film.

  The intrinsic viscosity (IV) of the PBT layer resin is preferably 0.65 to 0.85, and more preferably 0.70 to 0.80. The intrinsic viscosity (IV) is obtained by dissolving 300 mg of a sample resin in 30 ml of a solvent (phenol: 1,1,2,2-tetrachloroethane = mass ratio 1: 1), and using a Ubellose viscometer, Can be measured and calculated.

  The lower limit of the thickness of the PBT layer is preferably 1 μm or more, and more preferably 3 μm or more. The upper limit is preferably less than 20 μm, more preferably less than 15 μm, and still more preferably less than 10 μm. When the thickness is 1 μm or more, whitening during heat sealing can be suppressed. Further, when the total thickness is reduced by less than 20 μm, the PET layer adjacent to the PBT layer can be disposed thickly, and curling can be suppressed.

<Outer layer 2: Polyethylene terephthalate resin (PET) layer>
The outer layer 2 adjacent to the outer layer 1 of the film of the present invention is formed of a polyethylene terephthalate resin (PET) layer, and is formed by solidifying a crystalline polyester resin in an unstretched film to be amorphous.
By arranging a PET layer in the outer layer 2, rigidity, strength, moldability, and transparency can be imparted to the film. Further, since the cost is lower than that of the PBT resin, even if the layer thickness ratio is increased, the economy is good and the effect of imparting rigidity, strength, and moldability can be sufficiently exhibited.

  The PET layer resin of the film of the present invention can be formed of a polyvalent carboxylic acid component and a polyhydric alcohol component described below.

As the polyvalent carboxylic acid component, any of aromatic dicarboxylic acid, aliphatic dicarboxylic acid, and alicyclic dicarboxylic acid is used in addition to terephthalic acid constituting the ethylene terephthalate unit.
Examples of aromatic dicarboxylic acids include benzene dicarboxylic acids such as isophthalic acid, orthophthalic acid, and 5-tert-butylisophthalic acid; naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylic acid; 44-dicarboxydiphenyl and 2,2,6. Dicarboxybiphenyls such as 1,6-tetramethylbiphenyl-4,4′-dicarboxylic acid; 1,1,3-trimethyl-3-phenylindene-4,5-dicarboxylic acid and substituted products thereof; 1,2-di Examples include phenoxyethane-4,4′-dicarboxylic acid and substituted products thereof.
Aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, pimelic acid, suberic acid, undecanoic acid, dodecanedicarboxylic acid, brassic acid, tetradecanedicarboxylic acid, tapsinic acid , Nonadecane dicarboxylic acid, docosane dicarboxylic acid and the like. Furthermore, examples of the alicyclic dicarboxylic acid include 1,4-dicarboxycyclohexane and 1,3-dicarboxycyclohexane.

As the polyhydric alcohol component, in addition to ethylene glycol constituting the polyethylene terephthalate unit, any of aliphatic diol, alicyclic diol and aromatic diol can be used.
Examples of the aliphatic diol include diethylene glycol, propylene glycol, butanediol, 1,6-hexanediol, 1,10-decanediol, neopentyl glycol, 2-methyl-2-ethyl-1,3-propanediol 2-diethyl- Examples include 1,3-propanediol and 2-ethyl-2-n-butyl-1,3-propanediol.
Examples of the alicyclic diol include 1,3-cyclohexanedimethanol and 1,4-cyclohexanedimethanol.
As aromatic diols, ethylene oxide adducts of bisphenol compounds such as 2,2-bis (4′-β-hydroxyethoxydiphenyl) propane and bis (4′-β-hydroxyethoxyphenyl) sulfone; xylylene glycol, etc. Is mentioned.
Moreover, polyalkylene glycols, such as polyethylene glycol and polypropylene glycol, etc. can also be used as a polyhydric alcohol component.

In order to prepare a PET resin using such a polyvalent carboxylic acid component and a polyhydric alcohol component, in order to improve the properties as a coextrusion film for deep drawing, one or more polyvalent carboxylic acid components or multiple polycarboxylic acid components are used. A combination of monohydric alcohol components can be used. The kind and content of the monomer component to be combined can be appropriately determined based on desired film characteristics, economy and the like.
Moreover, a single copolymer resin may be used for PET resin, and it is also possible to use a mixture of two or more types of copolymer or homopolyester.

  In the PET layer resin of the present invention, it is preferable to use a resin having an ethylene terephthalate unit content of 80 mol% or more, more preferably 83 mol% or more, and still more preferably 85 mol% or more. Among these, homopolyethylene terephthalate and polyethylene terephthalate copolymer are preferred from the viewpoint of economy.

  The lower limit of the thickness of the PET layer is preferably 30% or more, more preferably 35% or more, and still more preferably 40% or more with respect to the total film thickness. The upper limit is preferably less than 75%, more preferably 70% or less, and still more preferably 65% or less. By being 30% or more, good stiffness and curl resistance can be obtained for the film. If it is less than 75%, the thickness of the gas barrier layer of the intermediate layer and the seal layer of the inner layer can be sufficiently secured, and these layers function effectively.

<Intermediate layer: Gas barrier layer>
The film of the present invention is desirably provided with an oxygen gas barrier property in the intermediate layer for the purpose of preventing the contents of the food from being spoiled.
As the gas barrier layer, a polyamide resin (PA) layer, an ethylene-vinyl acetate saponified copolymer (EVOH) layer, or a mixed resin layer of PA and EVOH can be provided. The gas barrier layer may be a single layer or a plurality of stacked layers.

The polyamide resin of the gas barrier layer is not particularly limited, but nylon resin (Ny) is preferably used from the viewpoint of gas barrier properties and pinhole resistance. For example, a polymer of a condensation unit such as 6 nylon, 66 nylon, 69 nylon, 6-66 nylon, 12 nylon, 11 nylon, 610 nylon, 612 nylon, 6I-6T nylon, MXD6 nylon, or two or more of these Mention may be made of copolymers and also mixtures thereof. Among them, it is preferable to use MXD6 nylon having high gas barrier property, 6 nylon or 6-66 nylon having high pinhole resistance.
The lower limit of the thickness of the PA layer is 2 μm or more, preferably 3 μm or more, and more preferably 5 μm or more. Moreover, an upper limit is 25 micrometers or less, Preferably it is 20 micrometers or less, More preferably, it is 15 micrometers or less. When it is 2 μm or more, good gas barrier properties and pinhole resistance can be easily obtained, and when it is 25 μm or less, good cut property in a deep-drawing packaging machine is easily obtained.

The EVOH resin of the gas barrier layer preferably has an ethylene content of 30 to 60 mol% and a saponification degree of 95% or more from the viewpoint of moldability and gas barrier properties.
The lower limit of the thickness of the EVOH layer is preferably 1 μm or more, and more preferably 2 μm or more. The upper limit is preferably 20 μm or less, and more preferably 10 μm or less. When it is 1 μm or more, good oxygen gas barrier properties are easily obtained, and when it is 20 μm or less, deterioration of pinhole resistance is easily suppressed.

<Intermediate layer: ethylene-vinyl acetate copolymer (EVA) layer, polyethylene resin (PE) layer>
In the film of the present invention, an ethylene-vinyl acetate copolymer (EVA) layer or a polyethylene resin (PE) layer can be disposed in the intermediate layer for the purpose of imparting flexibility.
Although the ethylene content of EVA is not particularly limited, it is preferably 1.5 mol% or more and 20 mol% or less, preferably 3 mol% or more and 15 mol% or less from the viewpoint of film formation stability. Is more preferable.
The resin for the PE layer is not particularly limited. For example, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), high density polyethylene (HDPE), or a mixture thereof can be used.

<Intermediate layer: Adhesive resin layer>
In the film of the present invention, an adhesive resin layer can be appropriately disposed between the outer layer and the intermediate layer and between the inner layer and the intermediate layer from the viewpoint of further increasing the interlayer adhesive strength. For example, it is preferable to dispose between the EVOH layer and the PE layer, between the PA layer and the PE layer, between the PET layer and the EVOH layer, and between the PET layer and the PA layer.

The adhesive resin is not particularly limited as long as various resin layers constituting each layer can be bonded with a required strength. A polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof is preferable. Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and the like.
In addition, unsaturated carboxylic acid esters and anhydrides can be used as adhesive resins, and derivatives such as methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate, Glycidyl acrylate, glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate and the like can be used.

<Inner layer: Easy peel (EP) layer>
The inner layer located on the container side when producing the film packaging of the present invention has an easy peel function.
The resin constituting the easy peel (EP) layer is not particularly limited as long as it has an easy peel function, and a mixture of two incompatible polyolefin resins can be used.
For example, a mixture of linear low density polyethylene (LLDPE) and polybutene (PB), a mixture of ethylene-vinyl acetate copolymer (EVA) and polypropylene (PP), a mixture of PP and low density polyethylene (LDPE), PP and Examples include mixing of ionomer (IO), mixing of PP and ethylene-acrylic acid copolymer (EAA), mixing of PP and ethylene-methyl methacrylate copolymer (EMMA), and the like. Among them, a mixture of LLDPE and PB or a mixture of PP and LDPE can be preferably used.

The lower limit of the thickness of the EP layer is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more, from the viewpoint of film formability and peel appearance. The upper limit is preferably 15 μm or less, more preferably 12 μm or less, and still more preferably 10 μm or less.
When the thickness is 2 μm or more, stable film-forming properties can be obtained, and when the thickness is 15 μm or less, fluffing and film residue can hardly occur during peeling, and a good peel appearance can be obtained.

  The easy peel strength (peel strength) of the film of the present invention may be any strength as long as cohesive failure occurs during peeling and the peeled surface is not fluffy. For example, at 25 ° C., the lower limit is 0.8 N / 15 mm width or more, preferably 1.0 N / 15 mm width or more, more preferably 1.2 N / 15 mm width or more, and the upper limit is 5.0 N / 15 mm width or less. Preferably it is 4.5 N / 15mm width or less, More preferably, it is 4.0 N / 15mm width or less.

<Whole film>
The total thickness of the film of the present invention is preferably 40 μm or more and less than 120 μm. The lower limit is more preferably 45 μm or more, and still more preferably 50 μm or more, from the viewpoint of film formation stability and film strength. The upper limit is more preferably 100 μm or less and even more preferably 80 μm or less from the viewpoint of reducing the packaging material.

The structure of the film of the present invention is not particularly limited as long as it has a layer structure in the order of a PBT layer, a PET layer, a gas barrier layer, and an easy peel layer.
For example, using abbreviations, PBT layer (A), PET layer (A ′), PA layer (B), EVOH layer (C), EVA layer or PE layer (D), easy peel layer (E), and adhesive resin When the layer (F) and each layer are described, the following layer structure can be formed.
(1) A / A '/ F / B / C / F / E
(2) A / A '/ F / B / C / F / D / E
(3) A / A '/ F / C / B / F / D / E
(4) A / A '/ F / C / B / F / E
(5) A / A '/ F / B / C / B / F / D / E
(6) A / A '/ F / B / F / C / F / D / E

  Among the above, from the viewpoint of improving pinhole resistance and deep drawing workability in addition to transparency, gloss, rigidity and curl resistance, the layer configuration of (2), (3) or (5) is preferable.

  The film of the present invention can be produced using a known method. For example, an extrusion lamination method, a coextrusion inflation method, a coextrusion T die method, and the like can be used, and it is particularly preferable to use a coextrusion T die method.

<Deep drawn package>
The film of the present invention can be used for a deep drawn package. In particular, when the film of the present invention is used as a bottom material of a deep drawn package, a good deep drawn package can be obtained. Deep drawing can be performed by a known method.
Moreover, the heat sealing conditions of the lid and the bottom material can adopt general conditions such as a temperature of 110 to 160 ° C. and a time of 1 second to 4 seconds, and even when the film is separated from the rubber packing in the heat sealing process. The film surface is not roughened and the appearance such as gloss of the package is not deteriorated.

  The lid material is not particularly limited as long as easy peel properties can be obtained. For example, a cover material obtained by dry laminating an expanded polypropylene resin film (OPP), a transparent vapor-deposited polyethylene terephthalate film, and a linear low density polyethylene (LLDPE) film, or an expanded polyethylene terephthalate (OPET) film, and EVOH or Ny and sealing LLDPE A laminate obtained by dry laminating a coextruded film as a layer can be mentioned.

Examples of the present invention will be described below, but the present invention is not limited thereto.
<Production of multilayer film>
A multilayer film having a layer structure shown in each example was produced by a coextrusion method. The layer structure is shown in the order from the outer layer to the inner layer. Moreover, the component of each layer was shown using the following abbreviation.
Moreover, the heat distortion temperature of resin is a measured value in ASTM D648 (0.455 MPa).

(Each layer component)
・ PBT: Polybutylene terephthalate homopolymer Thermal deformation temperature 136 ° C
PET: Polyethylene terephthalate homopolymer Thermal deformation temperature 68 ° C
PETG: Polyethylene terephthalate-glycol copolymer Thermal deformation temperature 85 ° C

Ny: 6-66 copolymer nylon Nylon 66 ratio 15%
EVOH1: Ethylene-vinyl acetate copolymer saponified product 38% by mole of ethylene
EVOH2: Saponified ethylene-vinyl acetate copolymer 32 mol% ethylene

LL: linear low density polyethylene EVA: ethylene-vinyl acetate copolymer EP: mixture of linear low density polyethylene and polybutene Mass mixing ratio = 60: 40
・ Adhesion: Unsaturated carboxylic acid modified polyolefin adhesive resin

Example 1
PBT (3 μm) / PET (30 μm) / adhesion (4 μm) / Ny (5 μm) / EVOH1 (5 μm) / adhesion (4 μm) / LL (5 μm) / EP (4 μm), total thickness 60 μm

(Example 2)
PBT (5 μm) / PET (28 μm) / Adhesion (4 μm) / EVOH 2 (5 μm) / Adhesion (4 μm) / EVA (10 μm) / EP (4 μm), Total thickness 60 μm

(Example 3)
PBT (1 μm) / PET (24 μm) / Adhesion (3 μm) / Ny (2 μm) / EVOH1 (3 μm) / Adhesion (3 μm) / LL (2 μm) / EP (2 μm), Total thickness 40 μm

Example 4
PBT (3 μm) / PET (40 μm) / Adhesion (3 μm) / Ny (3 μm) / EVOH1 (3 μm) / Adhesion (3 μm) / LL (3 μm) / EP (2 μm), Total thickness 60 μm

(Comparative Example 1)
PETG (33 μm) / adhesion (4 μm) / Ny (5 μm) / EVOH1 (5 μm) / adhesion (4 μm) / LL (5 μm) / EP (4 μm), total thickness 60 μm

(Comparative Example 2)
PBT (3 μm) / PET (10 μm) / adhesion (5 μm) / Ny (6 μm) / EVOH1 (8 μm) / adhesion (5 μm) / LL (18 μm) / EP (5 μm), total thickness 60 μm

(Comparative Example 3)
PBT (20 μm) / PET (17 μm) / adhesion (4 μm) / Ny (3 μm) / EVOH1 (4 μm) / adhesion (4 μm) / LL (3 μm) / EP (5 μm), total thickness 60 μm

  Using a deep-drawing packaging machine (FV6300 manufactured by Omori Machine Industry Co., Ltd.), using a multilayer film produced in each example as a bottom film under the conditions of a deep drawing heating temperature of 90 ° C. and a molding time of 1.5 seconds, respectively. 98mm, drawing depth 5mm, molded into a cylindrical shape, containing slice ham with a diameter of 95mm, 35g, heat-sealed together with the lid material film at 140 ° C for 2 seconds, vacuum packaged, 140mm in length, A 130 mm wide deep drawn package was produced.

The lid uses the following film:
・ OPP: Biaxially stretched polypropylene film ・ Transparent vapor-deposited PET: VM-PET manufactured by Toyo Melarizing
-LLDPE: A laminated film having the following constitution was prepared and used by a linear low density polyethylene film dry lamination method. “//” represents adhesion by a dry laminating method.
OPP (30 μm) // Transparent deposition PET (12 μm) // LLDPE (40 μm)

<Evaluation method>
The following evaluation was performed and the results are shown in Table 1. In addition, the outer layer located on the film surface was represented as “outer layer 1”.
(Heat seal curl)
Within 5 minutes after making the package, place the package on a horizontal base and observe it. The height from the horizontal base surface at the highest curl of the four corners of the heat-sealed flange of the package The height was measured and evaluated according to the following criteria.
“○”: When the flange is flat or when the maximum curl height is less than 3 mm “△”: When the maximum curl height is 3 mm or more and less than 5 mm “X”: When the maximum curl height is 5 mm or more

(Heat seal part whitening)
When the heat-sealed flange portion was observed, the case where whitening did not occur was evaluated as “◯”, and the case where it occurred was evaluated as “×”.

Examples 1-4 have good deep-drawing moldability, the curl of the heat seal part of the package is small, the packs are easy to align when applying labels, and the appearance is good without whitening during heat sealing Met.
On the other hand, in Comparative Examples 1 to 3, the heat-sealed flange portion is curled to the bottom material side, so that the package is not well aligned and conveyed in the labeler of the packaging line, and the labeling of the multi-pack is not bent or pasted. A problem occurred.
In Comparative Example 1, whitening occurred during sealing, and the appearance was poor. Surface roughness of the PETG layer disposed on the film surface layer was observed.

  According to the coextruded multilayer film for deep-drawing packaging of the present invention, it is possible to provide a thin film that is firm and has good curl without impairing transparency and gloss, and waste that halves the current market product Volume reduction can be realized and industrial value is high.

Claims (4)

  A co-polymer for deep-drawing packages having a polybutylene terephthalate resin layer, a polyethylene terephthalate resin layer, a gas barrier layer, and an easy peel layer in this order, and the ratio of the polyethylene terephthalate resin layer thickness to the total film thickness being 30% or more and less than 75%. Extruded unstretched film.   The coextruded unstretched film for deep-drawn packaging according to claim 1, wherein the total film thickness is 40 µm or more and less than 120 µm, and the polybutylene terephthalate resin layer thickness is 1 µm or more and less than 10 µm.   A bottom material for a deep-drawn package using the coextruded unstretched film for a deep-drawn package according to claim 1 or 2.   A deep-drawn package using the bottom material for the deep-drawn package.