JP2000128112A - Flexible multi-layered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a package which is excellent in transparency, glossiness, oxygen gas barrier property and resistance to shock and has a good appearance by using a gas barrier resin as an outermost layer, a constituent comprising a polypropylene-based resin containing a specific wt.% of thermoplastic elastomer as a core layer and a heat-sealable resin such as an ethylene-based resin as an innermost layer. SOLUTION: A gas barrier resin of an outermost layer 5 may be preferably EVOH or the like. In a constituent of a core layer 7, a propylene-based copolymer comprising a content of up to 7 wt.% of comonomer is used as a polypropylene-based resin, wherein a thermoplastic elastomer such as a hydrogenated styrene-butadiene copolymer may be preferably used by 10 to 70 wt.% for an entire constituent which constitutes the core layer 7. An ethylene-based polymer of a heat-sealable resin as an innermost layer 9 may be preferably a low density polyethylene or the like as well as an ethylene-α-olefin copolymer or the like. In order to apply or improve adhesion among the outermost layer 5, the core layer 7 and the innermost layer 9, adhesive layers 6, 8 may be provided as needed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film for packaging, and more particularly, to a soft multilayer film having a good appearance without gloss, transparency and wrinkles, and providing a vacuum package having oxygen gas barrier properties. The present invention relates to a film, in particular, a soft multilayer film for skin pack packaging suitable for food packaging.

[0002]

2. Description of the Related Art In recent years, in the field of food packaging, a packaging form having good appearance has been preferred. Among such packaging forms are draw packaging, for example, skin pack packaging and deep drawing packaging. These are widely used for packaging foods such as bacon, sausage, ham, meat, cheese and the like, since the package is vacuum-tightly packaged with a transparent packaging film and the packaging does not wrinkle.

According to the basic mode, as shown in FIG. 1, a skin pack package comprises a base material (base film) 1 having relatively high rigidity or mechanical strength, and a draw-formed heated base material as necessary. Between a softening film (lid material) 2, a printed mount 3 and a package or contents 4 of various foods and the like
Is placed, and the film 1 and 2 are evacuated so that the lid material film 2 adheres closely to the shape of the package 4 and the peripheral lid material 2 and the bottom material 1 are heat-sealed to form a skin pack package. A body is formed. For example, in the case of food packaging, the manufacturing company name, manufacturing date,
In many cases, texts and photographs of cooking examples are printed in color.
As shown in FIG. 2, the mount 3 may be omitted. In this case, printing is often performed on the inner surface of the bottom member 1 on the side of the package 4 or the outer surface or inner layer on the opposite side.

[0004] As one specific example of the skin pack packaging method,
There is a heating vacuum packaging method (Japanese Patent Publication No. 57-23607). Referring again to FIGS. 1 and 2, in this heating vacuum packaging method, a vacuum mold having a vacuum hole and a heater (that is, a chamber having a concave hot plate having a vacuum hole) is used.
, The lid material (skin film) 2 is preliminarily drawn and formed, while the packaged object 4 (and the backing sheet 3) is placed on the bottom material (base film) 1 which is to be fitted with the recess formed by the forming. Without cooling the drawn skin film 2 and keeping the heated and softened state, the peripheral portion PF of the recess and the base film 1 are combined to cover the packaged object, and the recess is evacuated. As well as
By returning the atmospheric pressure between the vacuum mold and the drawn skin film 2 to room temperature, the skin film 2 is brought into close contact with the shape of the package 4 and, at the same time, the skin film ( The lid material 2 and the base film (bottom material) 1 are heat-sealed.

[0005] The above-described skin pack packaging is different from general drawn packaging in that a preformed skin film is brought into close contact with an object to be packaged in a state of being heated and softened. That is,
In squeeze packaging, a film is previously formed into a container having a predetermined shape by a mold, and then the container is filled with an object to be packaged and then sealed in a vacuum. In this drawing method, voids are apt to remain between the container and the article to be packaged, causing problems such as separation of liquid juice, impairment of appearance due to generation of wrinkles and the like, and cause deterioration. Further, in this method, it is necessary to match the shape of the container to the shape of the article to be packaged. On the other hand, the film used in the skin pack packaging is preliminarily drawn and formed by a vacuum mold, but is kept covered with heat while being covered with the packaged object, and has flexibility.
Follows and adheres to the packaged object due to elastic recovery. However, the above-mentioned skin pack packaging method also has various modifications. For example, there is a method of filling a concave portion of a skin film formed by drawing with a packaged object such as sausage. Further, as a method for sealing the lid material and the bottom material, a sealing method using an adhesive or the like is used in addition to the heat sealing method.

[0006] According to the skin pack packaging, not only can the skin film and the article to be packaged be uniformly adhered, but also, for example,
Even if the shape of the packaged object is not standardized, such as a product in which sliced bacon is staggered, packaging is possible. However, if the flexibility and elastic recovery are small, the lid material film to be drawn and formed is sufficiently larger than the article to be packaged, so that the surplus portion becomes wrinkled. If the rigidity of the bottom material is high due to lack of flexibility, the rigidity of the bottom material is high, so if the skin pack products come into contact with each other during transportation, the other pack products may be damaged at the corner of the pack product, and the appearance and contents of the pack The quality of the product may be degraded.

The skin film (lid film) used in the above-mentioned skin pack packaging must have the following physical properties, including flexibility and sufficient elastic recovery at high molding temperatures. Required. First of all, when drawing on a skin film with a vacuum mold,
Heat resistance is required so that it does not fuse to a heated vacuum mold, and when molding, it locally expands, especially at the curve of the mold corner, and the ultra-thin portion does not cause pinholes in the package. You. Second, the skin film is required to have excellent transparency and gloss in order to increase the commercial value of the package. Third, the skin film is required to have an oxygen gas barrier property for packaging of articles to be packaged such as foods that need to be putrefied or stored for a long period of time. Therefore,
Many skin films have an oxygen gas barrier layer. Fourth, it is required to have an impact strength that can withstand an impact during transportation. Further, the skin film is required not to contaminate the packaged object and to have heat-sealing property with the bottom material (base film) when heat-sealing.

Conventionally, as a lid material film for skin pack packaging, for example, soft polyvinyl chloride resin (PVC) /
Unstretched co-extruded multilayer film composed of polyvinylidene chloride resin (PVDC) / polyolefin resin (PO) (Japanese Patent Publication No. 6-2485), flexible PVC / PVDC / E
VA multilayer film (JP-B-56-49206), ethylene-vinyl alcohol copolymer (EVO
H) / EVA1 / EVA2 layer-irradiated film (EVA1 and EVA2 are both ethylene-vinyl acetate copolymers but have different vinyl acetate contents), thermoplastic polyurethane (TPU) / EVOH /
Various multilayer films such as polyolefin resins have been proposed. In particular, a film having the above-mentioned flexibility is widely used because a soft packaged object used for a skin pack package is required to have faithful adhesion to the shape thereof.

Some of the conventional lidding films for skin pack packaging developed as described above are functionally excellent, but they are not always satisfactory. For example, a film having a laminated structure of flexible PVC / PVDC / PO or EVA is suitable for elastic recovery of flexible PVC and PVDC.
Although it is functionally suitable as a skin film due to its combination with the flexibility, a non-halogen film may be desired in consideration of the environment. In this regard, EVOH and E
A film obtained by irradiating the VA laminate with an electron beam is desirable, but the film is heated at the time of the electron beam irradiation and a slight stretching occurs in the machine direction (film winding direction, MD). Therefore, the anisotropy between the thinning of the film and the vertical direction (TD) of the MD increases, and wrinkles in the MD direction, curling of the film, etc. may occur during skin pack, and mechanical suitability may be impaired. . EVOH and EV without electron beam irradiation
The laminate of A has insufficient heat resistance, resulting in an extremely thin portion during skin molding. It has been proposed to introduce a polyamide (PA) layer in order to solve this lack of heat resistance.
According to the present inventors, it has been found that when the thickness of PA is increased to the extent that heat resistance is imparted, the packaged product after the skin pack has many wrinkles, deteriorates the appearance, and impairs the commercial value.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flexible multilayer film formed from a non-halogen resin material and suitable for skin pack packaging. More specifically, an object of the present invention is to provide
Provide a new flexible multilayer film with high flexibility and elastic recovery, no wrinkles on the package surface, excellent transparency and gloss, good appearance, oxygen gas barrier properties and impact resistance Is to do.

[0011]

The flexible multilayer film of the present invention has been developed to achieve the above-mentioned object. More specifically, the flexible multilayer film has an outermost layer (a) composed of a gas barrier resin and a polypropylene resin. 10-70% by weight
A core layer (b) composed of a composition containing a thermoplastic elastomer, an innermost layer (c) composed of a heat-sealable resin selected from an ethylene homopolymer or an ethylene-based copolymer, and, if necessary, the above-mentioned respective layers. Characterized by having an adhesive layer.

[0012] The present inventors have studied for the above-mentioned purpose, and will add a little about how they reached the present invention.

As a result of the present inventors' research on various thermoplastic resin materials for the above-mentioned purpose, first, a resin material having excellent flexibility and elastic recovery comparable to the conventionally used flexible PVC was replaced with a polypropylene resin, It has been found that a specific composition of a thermoplastic elastomer having good compatibility with the above is provided by a polymer alloyed composition. However, since the composition contains a thermoplastic elastomer, although the composition is improved by blending the polypropylene resin, the composition has lower heat resistance than the polypropylene resin alone. For this reason, a phenomenon was found in which the surface gloss was deteriorated when it was used as the outermost layer when it was brought into contact with a hot plate, although it was not so thin as to form the skin. Therefore, the composition is not preferable as a material constituting the outermost layer.

On the other hand, the present inventors have noticed that gas barrier resins other than PVDC, such as EVOH or polymeta-xylene adipamide (nylon MXD6), are inferior in flexibility but have good heat resistance. . That is,
If this is used as the outermost layer (a) to form a gas barrier resin layer, a surface layer having gloss and transparency that does not deteriorate even when it comes into contact with a hot plate is formed, and from the composition of the polypropylene resin and the thermoplastic elastomer, Flexible PVC / PV by ensuring flexibility in combination with the core layer (b)
A laminated structure of the outermost layer / core layer comparable to the combination of DC is obtained, and by further providing the innermost layer (c) composed of a heat-sealable resin layer, a soft multilayer film extremely suitable as a lid material for skin pack packaging is obtained. It has been found that the present invention is achieved. In addition, the flexible multilayer film of the present invention having such a laminated structure is subjected to stretching if necessary in addition to the cover material film for skin pack packaging, but if the shrinkage is too large, the package may be curled. Therefore, it is desirable to provide an appropriate shrinkage.

Further, the flexible multilayer film of the present invention has excellent moldability conventionally used for deep drawing films.
Resins such as polypropylene resin and ethylene (co) polymer are used in a thickness ratio of 80% or more. In addition, since the ratio of the resin that is relatively thin at the corners of the mold during molding, such as EVOH, is set to 20% or less as the gas barrier resin, it can be used as a multilayer film and for deep drawing without any problem.

Further, the flexible multilayer film of the present invention comprises:
It is also possible to use the skin pack package on the side where the skin is not molded, that is, on the bottom material side. In this case, if the multilayer film of the present invention is used also as a lid material film,
Since the upper and lower layers have a substantially symmetric layer configuration, crystallization after heat sealing is the same, and curling which is a problem in the package is effectively eliminated. Further, even when the corner of the package is a right angle, since the flexibility is (sufficient), the corner is hard and there is no problem in workability.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The flexible multilayer film of the present invention has a layer configuration as shown in FIG. 3 as a typical embodiment thereof. That is, this multilayer film is shown in FIG.
The outermost layer (a) is referred to
5, the core layer (b) 7 and the innermost layer (c) 9
8, the layers are sequentially laminated. The adhesive layers 6 and 8 are inserted as necessary in order to enhance the adhesiveness between the respective layers, and may be omitted.

As the gas barrier resin constituting the outermost layer (a), known EVOH and polymeta-xylene adipamide (nylon MXD6) are suitable in terms of extrusion processability. EVOH has an ethylene content of 36 to 47 mol%,
The melt flow rate (MFR, measured at 190 ° C. under a load of 2160 g according to JIS K-6730) is 0.1.
Those having 5 to 20 g / min are preferred. If the ethylene content is less than 36 mol%, the rigidity is high and wrinkles occur during skin molding. However, since the outermost layer (a) made of these gas barrier resins has high rigidity and lacks flexibility as compared with other layers, the outermost layer (a) should be within 20% of the total thickness of all layers to prevent wrinkles during skin molding. It is preferable from the viewpoint of prevention.

The polypropylene resin in the composition constituting the core layer (b) has a melting point of 140 ° C. to 165 ° C. (measured by the DSC method according to JIS K-7121),
Those having an R (measured at 230 ° C) of 0.3 to 20 g / min are preferred. Here, as the polypropylene-based resin, a propylene-based copolymer having a comonomer content of up to 7% by weight as compared with the propylene homopolymer is preferably used.
7.0% by weight of a propylene-ethylene copolymer (PP-
Et) is preferred. Among them, a random copolymer having excellent transparency and flexibility is more preferred. Furthermore, PP-Et to which a nucleating agent is added is more excellent in transparency. Also in the case of propylene homopolymer, good transparency can be obtained as long as it is a crystal nucleating agent-added product. In this case, the heat resistance is PP-Et.
Although it is more excellent, since the rigidity is large, it is desirable that the addition amount of the thermoplastic elastomer be larger than in the case of using the PP-Et system.

The nucleating agent refines the polypropylene spherulite generated in the cooling process after molding, and increases the transparency of the core layer (a),
In order to improve the transparency of the flexible multi-layer film, it is preferable that the resin is contained in the polypropylene-based resin at a ratio of about 0.1% by weight, and the aromatic phosphate ester salt, sorbitol-based, carboxylic acid A system crystal nucleating agent is used.

Core layer (b) with polypropylene resin
As the thermoplastic elastomer constituting the core layer (b)
In order not to deteriorate the transparency of the resin, those having excellent compatibility with the polypropylene resin are preferable. Examples of the thermoplastic elastomer include a hydrogenated product of a styrene-butadiene copolymer (SEBS, HSBR), an ethylene-propylene copolymer (EPR), a hydrogenated product of a crystalline olefin-butadiene copolymer (CEBC), or Ultra-low-density polyethylene (SSC-VLDPE) or an ethylene-α-olefin copolymer having a density of 0.91 g / cm ³ or less polymerized using a metallocene catalyst is preferred. These have the effect of not only imparting flexibility and elastic recovery to the polypropylene resin, but also improving the low-temperature strength. The thermoplastic elastomer needs to be 5 to 75% by weight of the entire composition constituting the core layer (b), preferably 10 to 70% by weight, particularly preferably 20 to 50% by weight. 5%
If it is less than 75, flexibility and elastic recovery are poor, and if it exceeds 75, heat resistance is poor. In particular, the transparency and gloss are also improved because the random PP-Et containing a nucleating agent and the styrene content are 1%.
5% or less styrene-butadiene random copolymer (HS
(BR) or a combination with a crystalline olefin-butadiene copolymer (CEBC).

For example, by adding HSBR,
HSB with reduced spherulite size of polypropylene resin
Since the dispersion unit of R can be a fine dispersion of visible light or less, transparency and gloss can be improved.

As the resin for the heat seal layer constituting the innermost layer (c), an ethylene homopolymer or an ethylene copolymer is preferably used. The innermost layer (c) is a layer that is in close contact with the item to be packaged in the skin pack packaging, and is a layer for heat-sealing the flexible multilayer film to the base film (bottom material).

Ethylene (co) constituting the innermost layer (c)
Examples of the polymer include low-density polyethylene (LDP)
E), linear low-density polyethylene (LLDPE), very-low-density polyethylene (VLDPE), very-low-density polyethylene polymerized using a single-site catalyst (SSC-VL)
DPE) and ethylene-α-olefin copolymer,
Ethylene-vinyl acetate copolymer (EVA), ethylene-
Acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), and ionomer (IO) It is preferably used.

Further, in order to facilitate the opening of the lid material and the bottom material of the package (providing easy open property), ethylene (co) weight such as IO, EVA and EMAA constituting the heat seal layer is used. 5 to 30% by weight of PP can be added to the union.

An appropriate amount of a lubricant may be added to the heat seal layer (c). In this case, preferred examples include organic lubricants such as behenic amide, oleic amide and erucamide, silica and zeolite. And inorganic lubricants such as calcium carbonate. The addition amount is preferably from 0.2 to 2% by weight. Lubricants are usually added in the form of a masterbatch. For example, the addition amount can be obtained by adding 1 to 10% by weight of a master batch containing 20% by weight of a lubricant.

In the multilayer film of the present invention, as shown in FIG. 3, adhesiveness is provided between the outermost layer (a) 5, the core layer (b) 7 and the innermost layer (c) 9, or Adhesive layers 6 and / or 8 can be provided as needed to enhance the adhesion. Particularly, since the outermost layer (a) and the core layer (b) have poor adhesion even when co-extruded, it is usually preferable to arrange an adhesive layer between both layers.

The adhesive resin used for the adhesive layer includes, for example, EVA, ethylene-maleic anhydride copolymer,
AA, EEA, ethylene-methacrylate-glycidyl acrylate terpolymer, or various polyolefins may be added to monobasic unsaturated fatty acids such as acrylic acid and methacrylic acid, or to dibasic acids such as maleic acid, fumaric acid, and itaconic acid. Examples thereof include those obtained by grafting a saturated fatty acid or an anhydride thereof, such as maleic acid-grafted EVA and maleic acid-grafted ethylene-α-olefin copolymer.

The multilayer film of the present invention can be formed by a coextrusion method, a dry lamination method, or the like. Preferably, a plurality of extruders are used to form a molten ring (co-extrusion) from each material by a coextrusion method. An extruded parison is extruded, and air is blown into the extruded parison to form a film.

In the flexible multilayer film of the present invention, the thickness of the outermost layer (a) 5 is 5 to 30 μm, preferably 10 to 2 μm.
0 μm, the thickness of the core layer (b) 7 is 5 to 80 μm, preferably 10 to 50 μm, and the thickness of the innermost layer (c) 9 is 10 to 100 μm, preferably 20 to 80 μm,
It is preferable that the thickness of the adhesive layers 6 and / or 8 inserted as needed is 1 to 20 μm, and the thickness of all layers is 50 to 210 μm, particularly 100 to 150 μm. Further, in order to prevent wrinkles from occurring during the formation of the skin pack, it is preferable that the thickness of the outermost layer (a) 5 having high rigidity be within 20% of the total layer thickness.

As described above, the soft multilayer film of the present invention is preferably used as a lid material film for skin pack packaging, but the constitution of the bottom material film to be combined at this time is basically arbitrary. For example, those having the following layer configurations as the outermost layer / core layer / seal layer are preferably used.

(A) Polypropylene resin / EVOH or MXD6 / ethylene resin seal layer (b) EVOH / LDPE / ethylene resin seal layer (c) EVOH / polyamide / ethylene resin seal layer In (2), the EVOH layer may be replaced with the core layer.

[0033]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. The various physical properties of the film were measured by the following test methods.

(1) Suitability for skin pack Skin pack test chamber manufactured by Omori Machinery Co., Ltd. (molding mold: depth 18 mm, length 120 mm, width 245 m)
Using m), a skin pack package having the configuration as shown in FIG. 1 was formed, and the condition of the package surface was determined. That is, 150 g of bacon is placed as the contents 4 on the backing 3 having a size of 235 mm × 115 mm, and the laminated structure as the bottom material film 2 is a polypropylene resin containing 5% HSBR // EVOH // EVA (// is an adhesive resin). Acid-modified PP-Et and acid-modified EVA, respectively, and the thickness of each layer is 35/3/19/3/40 μm,
(The total thickness is 100 μm) and sandwiched between the sample skin film 1 and vacuum skin pack packaging, and the surface (lid material side) side of the obtained package (pack product) is as follows. The evaluation was based on the following criteria.

<1> Wrinkles A: There are no wrinkles on the entire surface of the package. B: Short and shallow wrinkles occur at the filling section corner. C: Long and deep wrinkles occur on the entire surface of the package. <2> Followability A: The followability of the skin film is good with respect to the unevenness of the filler, and there is no gap. B: The convex part of the filler is crushed or the adhesion to the concave part is small. C: The filling material is greatly deformed, and the gravy is squeezed out or accumulated. <3> Heat resistance (melt hole MH, fusion to hot plate) A: There is no roughening at the time of hot plate adhesion, and the thinned portion at the hot plate corner has a thickness of 30% or more of all layers. maintain. B: Although there is no roughening on the hot plate, the thickness of the thinned portion at the corner of the hot plate is less than 30% of all layers. However, no melt holes are generated. C: The surface of the hot plate is roughened to deteriorate the gloss, or a melt hole due to thinning is generated.

(2) Transparency Regarding the molded multilayer film, JIS K-7015
The haze was measured by NDH- # 80 manufactured by Nippon Denshoku Industries Co., Ltd. The unit of the measured value is%.

(3) Gloss According to JIS K-7105, VGS manufactured by Nippon Denshoku Industries Co., Ltd.
According to-# 80, the gloss (Gloss) of the outermost layer side of the formed multilayer film was measured. Further, the measurement was performed in two directions with the film winding direction being MD and the vertical direction being TD in the film forming apparatus. The unit of the measured value is%.

(4) Impact strength Drop weight impact tester (“Drop W” manufactured by Rheometrics Inc.)
right Tester ”RDT-500)
The energy until the film was broken was measured to determine the film strength. At that time, it was visually determined whether or not the film was in a brittle state in which the state of the film was broken in a glass state or in a stretched state in which the film was stretched and broken. In the case of distribution in a packaged product, when the film used is brittlely broken at that temperature, the film strength tends to be significantly reduced.

The measurement was carried out using a sample film having an inner diameter of 3.8 cm.
And the center of the ring is 4 kg in weight from the outermost layer (a) side of the multilayer film, and the diameter of the weight is 12.7 mm.
Was dropped at a speed of 2 m / sec to break it, and the accumulated applied energy up to the break at that time was automatically measured. The temperature at the time of measurement was 23 ° C. and −5 ° C. The unit of the measured value is J.

(5) Oxygen gas permeability According to JIS K-7126, an oxygen gas permeability measuring instrument (“OX-TRA” manufactured by Modern Controls)
N2 / 20 ") at a temperature of 30 ° C. and a relative humidity of 80%
It was measured under the condition of RH. The unit of the measured value is cm ³ / m ^2.
24 h · atm.

Example 1 A five-layered multilayer film (corresponding to layers 5 to 9 in FIG. 3) was formed using the following five types of resin materials. Outermost layer: EVOH1 (manufactured by Nippon Synthetic Chemical Company, Soarnol A4412B) density = 1.14 g / cm ³ , MFR = 1
2 g / 10 min (measured at 210 ° C.), melting point = 164 ° C.,
Ethylene content = 44 mol%. Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Density = 0.89 g / cm ³ , MF
R = 2.8 g / 10 min (measured at 230 ° C.), melting point = 1
35 ° C. Core layer: PP-Et (Novatec E, manufactured by Nippon Polychem Co., Ltd.)
G7HT) and HSBR (1320P, manufactured by JSR)
Dry blending was performed at a ratio of 0/40% by weight. PP-E
t (Nippon Polychem, Novatec EG7HT) Density =
0.91 g / cm ³ , MFR = 1.7 g / 10 min
(Measured at 230 ° C.), melting point = 149 ° C., ethylene content =
3% by weight, HSBR (Dynalon 1320 manufactured by JSR)
P) Density = 0.89 g / cm ³ , MFR = 3.5 g / 1
0 min (measured at 230 ° C.), styrene content = 10% by weight. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Density = 0.906g / cm ^3, M
FR = 2.2 g / 10 min (measured at 190 ° C.), melting point =
120 ° C. Heat seal layer (innermost layer): EVA (Evaflex V527-4, manufactured by Mitsui DuPont Polychemicals) density =
0.94 g / cm ³ , MFR = 0.7 g / 10 min
(Measured at 190 ° C.), melting point = 83 ° C., vinyl acetate content =
17% by weight.

In forming a multilayer film, five extruders were used, and EVOH1 / adhesive layer / (blend of PP-Et and HSBR <60/40>) / adhesive layer / EVA
In the five-layer laminated film of Example 1, the molten ring was extruded by a co-extrusion method by associating one EVOH layer with the outermost layer through five channels in a circular die. The temperature at the exit of the die was 210 ° C., an annular film having a folding width of 570 mm was formed by the direct inflation method, and both ends were slit by 10 mm to obtain a 550 mm raw film. The thickness (μm) of the obtained film is 1
0/3/30/3/54, totaling 100 μm.

Example 2 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1, except that the layer structure was changed as follows. Outermost layer: EVOH1 (manufactured by Nippon Synthetic Chemical Company, Soarnol A4412B) Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Core layer: PP-Et (Novatec E, manufactured by Nippon Polychem)
G7HT) and HSBR (1320P, manufactured by JSR)
Dry blending was performed at a ratio of 0/40% by weight. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): Density of EMAA (Nucrel N0903HC, manufactured by DuPont-Mitsui Polychemicals) =
0.93 g / cm ³ , MFR = 3.3 g / 10 min
(Measured at 190 ° C.), melting point = 98 ° C., methacrylic acid content = 9% by weight.

The thickness (μm) of the obtained film was 10/3/30/3/54 from the outermost layer, that is, 100 μm in total.

Example 3 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1, except that the layer structure was changed as follows. Outermost layer: EVOH1 (manufactured by Nippon Synthetic Chemical Company, Soarnol A4412B) Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Core layer: PP-Et (Novatec E, manufactured by Nippon Polychem)
G7HT) and HSBR (1320P, manufactured by JSR)
Dry blending was performed at a ratio of 0/40% by weight. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): VLDPE (Affinity PL1880, manufactured by Dow Chemical Company) Density = 0.90
2 g / cm ³ , MFR = 1.0 g / 10 min (190
° C), melting point = 98 ° C.

The thickness (μm) of the obtained film was 10/3/30/3/54 from the outermost layer, that is, 100 μm in total.

Example 4 PP-Et and HSBR of the core layer
Extrusion film formation was carried out in the same manner as in Example 1 except that the blend ratio was 80/20% by weight to obtain a multilayer film having a five-layer structure. The thickness (μm) of the resulting film was 10/3/20/3/64 from the outermost layer, for a total of 100 μm.

Example 5 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1, except that the layer structure was changed as follows. Outermost layer: EVOH1 (manufactured by Nippon Synthetic Chemical Company, Soarnol A4412B) Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Core layer: PP-Et (Novatec E, manufactured by Nippon Polychem)
G7HT) and HSBR (1320P, manufactured by JSR)
Dry blending was performed at a ratio of 0/50% by weight. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): IO (manufactured by Mitsui DuPont Polychemicals, Himilan 1601) Density = 0.94 g
/ Cm ³ , MFR = 1.2 g / 10 min (measured at 190 ° C.), melting point = 96 ° C., methacrylic acid content = 9% by weight.

The thickness (μm) of the obtained film was 10/3/30/3/54 from the outermost layer, that is, a total of 100 μm.

Example 6 A multilayer film having a five-layer structure was obtained in the same manner as in Example 1, except that the layer structure was changed as follows. Outermost layer: EVOH2 (manufactured by Nippon Synthetic Chemical Company, Soarnol E3808BN) density = 1.17 g / cm ³ , MFR =
3.2 g / 10 min (measured at 210 ° C.), melting point = 173
° C, ethylene content = 38 mol%. Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Core layer: PP-Et (Novatec E, manufactured by Nippon Polychem)
G7HT) and HSBR (1320P, manufactured by JSR)
Dry blending was performed at a ratio of 0/40% by weight. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): EVA (Evaflex V527-4, manufactured by Mitsui DuPont Polychemicals) The thickness (μm) of the obtained film is 10/3 that of the outermost layer.
/ 30/3/54, totaling 100 μm.

Examples 7 to 9 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1 except that the core layers were changed as follows. (Example 7): PP-Et (manufactured by Nippon Polychem, Novatec EG7HT) and CEBC (manufactured by JSR, 6200)
P) was dry blended at a ratio of 60/40% by weight. CEBC (hydrogenated product of olefin-butadiene block copolymer): (Dynalon 6200P manufactured by JSR) Density = 0.88 g / cm ³ , MFR = 2.5 g / 10 mi
n (measured at 230 ° C). (Example 8): PP-Et (Novatec EG7HT, manufactured by Nippon Polychem Co., Ltd.) and SEBS (Tuftec H1041, manufactured by Asahi Kasei Corporation) were dry-blended at a ratio of 60/40% by weight. SEBS (hydrogenated styrene-butadiene block copolymer): (ToughTech H1041 manufactured by Asahi Kasei Corporation) Density = 0.91 g / cm ³ , MFR = 5.0 g / 10 mi
n (measured at 230 ° C.), styrene content = 30% by weight. Example 9: PP-Et (Novatec EG7HT, manufactured by Nippon Polychem) and S-VLDPE (Engage EG8100, manufactured by Dow Chemical) were dry-blended at a ratio of 60/40% by weight. S-VLDPE (ultra low density polyethylene polymerized using a single site catalyst (metallocene catalyst)): (Engage EG8100, manufactured by Dow Chemical Company) Density =
0.87 g / cm ³ , MFR = 1.0 g / 10 min
(Measured at 230 ° C), melting point = 64 ° C.

In each case, the thickness (μm) of the obtained film was 10/3/30/3/5 from the outermost layer.
4 was 100 μm in total.

Comparative Example 1 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1 except that the layer structure was changed as follows. Outermost layer: EVOH1 (manufactured by Nippon Gohsei, Soarnol A4412B) Adhesive layer (outer layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.)
Admer NF528) Core layer: EVA (Evaflex V527-4, manufactured by Mitsui DuPont Polychemicals) Adhesive layer (inner layer): Acid-modified VLDPE (Mitsui Chemicals, Inc.)
Admer NF528) Heat seal layer (innermost layer): EVA (Evaflex V527-4, manufactured by Mitsui DuPont Polychemicals) The thickness (μm) of the obtained film is 10/3 that of the outermost layer.
/ 30/3/54, totaling 100 μm.

Comparative Example 2 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1, except that the layer structure was changed as follows. Outermost layer: EVOH1 (manufactured by Nippon Gohsei, Soarnol A4412B) Adhesive layer (outer layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.)
Admer NF528) Core layer: Polyamide Ny6-66 (Amilan CM6241M, manufactured by Toray Industries, Inc.) Density = 1.13 g / cm ³ , JIS-
Relative viscosity according to K6810 = 4.2, melting point = 190
° C. Adhesive layer (inner layer): acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): E
VA (Evaflex V527-4, manufactured by Mitsui DuPont Polychemicals) The thickness (μm) of the obtained film is 10/3 from the outermost layer.
/ 15/3/69 was 100 μm in total.

[Comparative Example 3] A multilayer film having a five-layer structure was obtained by extrusion film formation in the same manner as in Example 1 except that the core layer was made of PP-E alone. Thickness of obtained film (μm)
Is 10/3/20/3/64 from the outermost layer, a total of 100 μm
Met.

Comparative Example 4 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1 except that the core layer was made of HSBR alone. The thickness (μm) of the obtained film was 10/3/30/3/54 from the outermost layer, that is, 100 μm in total.

Comparative Example 5 A multilayer film having a five-layer structure was obtained by the same extrusion film forming method as in Example 1 except that the layer structure was changed as follows. Outermost layer: PP-Et (Novec EG7HT, manufactured by Nippon Polychem) and HSBR (1320P, manufactured by JSR) were dry-blended at a ratio of 60/40% by weight. Adhesive layer (outer layer): acid-modified PP-Et (manufactured by Mitsui Chemicals, Inc.
Admer QB550) Core layer: EVOH1 (manufactured by Nippon Synthetic Chemical Company, Soarnol A)
4412B) Adhesive layer (inner layer): Acid-modified VLDPE (manufactured by Mitsui Chemicals, Inc.
Admer NF528) Heat seal layer (innermost layer): EVA (Evaflex V527-4 manufactured by DuPont-Mitsui Polychemicals) The thickness (μm) of the obtained film is 30/3 that of the outermost layer.
/ 10/3/54, totaling 100 μm.

The results of evaluating the physical properties of the multilayer films obtained in the above Examples and Comparative Examples are summarized in Tables 1 and 2, respectively. The following can be seen from the results shown in Tables 1 and 2.

[Skin pack suitability] The multilayer film of Comparative Example 2 in which a rigid nylon core layer was introduced and combined with the outermost layer of EVOH also having a high rigidity and had a total thickness of 20 μm or more was obtained as a result of skin molding. Although it was not extremely thinned, wrinkles were frequently generated and the appearance was poor. In Comparative Example 1 in which EVA having poor heat resistance was used for the core layer and Comparative Example 4 in which HSBR was used alone, extremely thinning occurred at the corners of the hot plate or the occurrence of melt holes, resulting in poor skin suitability.
Comparative Example 5 has a laminated configuration in which the outermost layer and the core layer are replaced with each other as compared with Example 1, and therefore, no ultra-thinness occurred.
Traces of the hot plate were transferred to the film surface and roughening occurred. The skin pack suitability of the other examples and comparative examples was not problematic, and the appearance was excellent.

[Transparency, Gloss] Transparency was slightly inferior to Comparative Example 3 in which PP-Et alone was used for the core layer, but not at a problematic level. The gloss was slightly inferior to Comparative Example 5 in which EVOH was used for the core layer.
The comparative example exhibited excellent gloss because EVOH was used for the surface layer. These results are measurements before skin molding,
The tendency was the same after skin molding.

[Impact Strength] The strength, which is an important physical property when the package is transported, is also determined by adding a thermoplastic elastomer to the polypropylene resin constituting the core layer.
The effect of strength improvement was seen. Comparative Example 3, in which PP-Et alone was disposed in the core layer, exhibited the same strength at 23 ° C. (normal temperature) as in the other examples, but exhibited brittle fracture at −5 ° C. and was inferior in impact strength. Therefore, there is a problem when forming a package that flows at a low temperature.

[Oxygen gas permeability] Regarding the oxygen gas permeability, since the EVOH layer was inserted with a thickness of 10 μm,
All films showed excellent oxygen barrier properties.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

As described above, according to the present invention, the outermost layer (a) comprises a gas barrier layer, and the core layer (b) comprises a composition containing 10-70% by weight of a thermoplastic elastomer in addition to a polypropylene resin. A flexible multilayer film using a heat-sealing resin such as an ethylene-based (co) polymer for the first layer and the innermost layer (c) is provided.

The flexible multilayer film of the present invention, when used as a lid material for skin pack packaging, has skin pack suitability with excellent adhesion without wrinkles and the like, and also has transparency, gloss, oxygen gas barrier properties, and resistance to oxygen. Also shows excellent properties in impact properties. In addition, it is also suitable as a film for deep drawing or a bottom material film for skin pack packaging.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment (with a backing paper) of a skin pack package of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment (without a backing sheet) of the skin pack package of the present invention.

FIG. 3 is a cross-sectional view of the flexible multilayer film of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Skin pack bottom material film 2 Skin pack lid material film 3 Skin pack mount 4 Contents 5 Outermost layer (gas barrier layer) 6 Adhesive layer 7 Core layer (composition layer of polypropylene resin and thermoplastic resin) 8 Adhesive layer 9 Inner layer (heat seal layer)

 ──────────────────────────────────────────────────の Continued on the front page F-term (reference) 3E051 AA09 AB05 BA05 CB03 EA03 FB01 JA02 4F100 AJ07B AK04C AK06C AK07 AK28B AK46 AK62C AK63C AK64B AK69A AK70C AK71C AK73B AL01 BA03 BA03 BA03 BA03 BA03 BA03 BA03 JK13 JL12C JN01 JN21 YY00A YY00B YY00C

Claims (8)

[Claims] 1. An outermost layer (a) made of a gas barrier resin, a core layer (b) made of a composition containing 5 to 75% by weight of a thermoplastic elastomer in addition to a polypropylene resin, an ethylene homopolymer or an ethylene copolymer. A flexible multilayer film having an innermost layer (c) made of a heat-sealable resin selected from a polymer and, if necessary, an adhesive layer between the layers. 2. The multilayer film according to claim 1, wherein the thermoplastic elastomer is a hydrogenated diene copolymer. 3. The hydrogenated diene-based copolymer is a hydrogenated styrene-butadiene random copolymer.
2. The multilayer film according to item 1. 4. The gas barrier resin of the outermost layer (a) is an ethylene-vinyl alcohol copolymer.
The multilayer film according to any one of the above. 5. The method according to claim 1, wherein the polypropylene resin of the core layer (b) is a propylene-ethylene random copolymer.
5. The multilayer film according to any one of items 1 to 4. 6. The heat sealing resin of the innermost layer (c) is ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, linear low-density polyethylene,
The multilayer film according to any one of claims 1 to 5, which is an ultra-low density polyethylene or an ionomer. 7. The outermost layer (a) has a thickness of 5 to 30 μm, the core layer (b) has a thickness of 5 to 80 μm, and the innermost layer (c) has a thickness of 10 to 100 μm. ~ 2
0 .mu.m and a total thickness of 50 to 210 .mu.m.
7. The multilayer film according to any one of claims 6 to 6. 8. The multilayer film according to claim 1, which constitutes a lid for skin pack packaging.