JPH07102653B2 - Multi-layer film and skin pack - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a multilayer film having a high gas barrier property, which has significantly improved moldability during packaging and appearance quality after packaging in the field of food packaging. Relates to a skin pack using.

B. Conventional Technology Conventionally, a skin pack package has contents placed on a film or sheet-like material (hereinafter abbreviated as a lid material) which is a base material, without changing the shape of the contents. It is a packaging form obtained by covering the contents with a skin layer that adheres closely to the surface of the contents and adhering at the joint surface of this skin layer and the lid material, which plays a role in improving the product value in terms of its packaging appearance. It is connected. That is, the laminated film for skin pack packaging is used as the skin layer of the package.

By imparting gas barrier properties to the laminated film for skin pack packaging, the contents, raw meat, processed meat,
It is possible to improve the long-term storability of foods such as raw confectionery.
By the way, saponified ethylene-vinyl acetate copolymer (EV
OH) has the highest oxygen gas barrier property among thermoplastic plastics, and it is widely accepted in the world that the long-term storability of contents is high in the food packaging field.
Research on using this EVOH resin in a skin pack package has been actively conducted, and is also used in part.

However, the multilayer film for skin packs using this EVOH resin has not yet been obtained with sufficient performance due to problems in the packaging appearance described later, and therefore the packaging appearance is good, but the gas barrier Currently, PVDC-based resins, which have major problems in terms of properties and waste, are used.

By the way, as a multilayer film for skin packs using EVOH resin, PA (polyamide resin) / EVOH / sealant {PE (polyethylene), EVAC (ethylene-vinyl acetate copolymer), IO (ionomer resin), etc.}, IO / Multilayer films such as EVOH / sealant, polyvinyl chloride (PVC) / EVOH / sealant, EVAC / EVOH / sealant, crosslinked EVAC / EVOH / sealant are known. However, the multilayer film has a poor moldability to the contents after packaging, and the contents are easily crushed or wrinkled, so that a good packaging state cannot be obtained at present.

C. Problem to be Solved by the Invention The present invention is to provide a high-gas barrier multi-layer film and a skin pack which are largely prevented from being crushed or wrinkled after packaging.

D. Means for Solving the Problems The above problems include an ethylene content of 20 to 60 mol% and a saponification degree of 90.
% Or more of saponified ethylene-vinyl acetate copolymer (EVO
H) (A) layer or at least a composition (C) layer obtained by blending the EVOH (A) with a polyolefin silane (B) having a vinylsilane compound content of 0.005 to 5 mol% and a layer comprising the polyolefin (B). It is achieved by using a multilayer film having two layers and satisfying the following formulas (I) to (II) in a tensile-recovery test at a measuring temperature (T) of 60 ° C to 230 ° C.

0.0001t ≤ F ≤ 0.01t (I) 0 ≤ R ≤ 0.15t (II) where, t: strain (5% ≤ t ≤ 50%) F: stress generated when strain t is applied (kg / mm ² ) R: Residual strain (%) when stress F and strain t are given and then immediately stress F is set to 0. The present inventors have developed an EVOH composition obtained by blending EVOH (A) or EVOH with various thermoplastic resins. And a thermoplastic resin as a base material, and in some cases, an adhesive resin for adhering the two together, a multi-layer film is prepared by a co-extrusion method, and the obtained multi-layer film is used as a skin layer to package a skin pack. I ran the test.

First, various thermoplastic resins as a base material for EVOH (A), such as EVAC, IO, and PVC, and EVA as a sealant layer.
A packaging test of a skin pack was performed using a multilayer film in which C was laminated. As a result, defects such as crushing of the contents, wrinkles, tearing of the film, delamination, and whitening, which are problematic in terms of packaging appearance, occurred. Especially, the crushing and wrinkling of the contents were particularly problematic.

Therefore, as a result of further studies, the present inventors surprisingly found that when a multilayer film in which vinylsilane-modified polyolefin (B) was laminated on the EVOH (A) layer and EVAC as the sealant layer was used, the contents collapsed. It was found that a product with a good packaging appearance, which had few wrinkles and no wrinkles was obtained. Furthermore, as a result of intensive studies, the present inventors have adjusted the vinylsilane content of the vinylsilane-modified polyolefin copolymer (B), the presence or absence of a catalyst, the type of the catalyst, the wet heat treatment conditions, etc., and measured the temperature (T) 60 It was found that, when the multilayer film satisfying the formulas (I) to (II) is used in the range of ℃ to 230 ℃, a package having a very good appearance can be obtained, and the present invention was completed. Measurement temperature (T) 60
Satisfying the formulas (I) to (II) at ℃ to 230 ℃ means that the formula (I) to at least one point of 60 ℃ to 230 ℃.
To satisfy (II).

As a result of further detailed investigations by the present inventors, EVOH
As the layer (A), a composition (C) layer obtained by blending 30 to 97% by weight of the EVOH (A) resin with 3 to 70% by weight of the vinylsilane-modified polyolefin (B) was laminated on the vinylsilane-modified polyolefin (B). Multi-layer film (however, EVOH
Resin (B) to be blended with (A) and resin (B) to be laminated
Is the same as or different from each other}, a package having a better appearance can be obtained, and, surprisingly, as the EVOH (A) resin used, Contains 0.0005 to 5 mol% of vinylsilane compound
It was found that the effect is further improved when EVOH resin (A ') is used. The details of the present invention will be described below.

In the present invention, EVOH (A) is a saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol%, preferably 25 to 60 mol%, and a saponification degree of the vinyl acetate component of 90. % Or more, preferably 95% or more, more preferably 97
% Or more can be used. When the ethylene content is less than 20 mol%, the melt moldability is poor, while when it exceeds 60 mol%, the gas barrier property is insufficient. If the degree of saponification is less than 90%, gas barrier properties and thermal stability will be poor. EVOH
As (A), a vinylsilane compound is 0.0005 to 5 mol%, preferably 0.005 to 0.5 mol%, and more preferably 0.008 to
EVOH (A ') obtained by copolymerizing 0.2 mol% is more preferable. By using such EVOH (A '), the effect of improving the packaging appearance becomes more remarkable.

Further, the EVOH (A) and (A ′) are other comonomers such as propylene, butylene, unsaturated carboxylic acid or an ester thereof ((meth)) as long as the object of the present invention is not impaired.
It may be copolymerized with acrylic acid, (meth) acrylic acid ester (methyl, ethyl), etc., vinylpyrrolidone (N-vinylpyrrolidone, etc.), and further, a plasticizer, a heat stabilizer, an ultraviolet absorber, an antioxidant. , Blending with colorants, fillers, other resins (polyamide, partially saponified ethylene-vinyl acetate copolymer, etc.), or EV
It is also free to blend OH (A) and EVOH (A '). Further, the EVOH used in the present invention has a suitable melt index (MI) (190 ° C., under a load of 2160 g) of 0.1 to 50 g / 10 mi.
n., optimally 0.5-20g / 10min.

By the way, as the vinylsilane compound used for EVOH (A ′), compounds represented by the following (X), (Y) and (Z) are preferable.

[Wherein n is 0 to 1, m is 0 to 2, R ¹ is a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R ² is an alkoxyl group having 1 to 40 carbon atoms, The alkoxyl group may have a substituent containing oxygen. R ³ is hydrogen or a methyl group, R ⁴ is a hydrogen atom or a lower alkyl group, R ⁵ is an alkyl group or a divalent organic residue in which a chain carbon atom is bonded to oxygen or nitrogen, and R ⁶ is hydrogen. , Halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R ⁷ is an alkoxyl group or an acyloxyl group (wherein the alkoxyl group or the acyloxyl group may have a substituent containing oxygen or nitrogen). Good), R ⁸ is hydrogen, halogen,
A lower alkyl group, an allyl group, or a lower alkyl group having an allyl group, R ⁹ is a lower alkyl group. ] More specifically, R ¹ is a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms, R 1 ⁴ represents a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, R ⁵ represents an alkyl group having 1 to 5 carbon atoms or a divalent organic residue in which chain carbon atoms are bonded to each other through oxygen or nitrogen. R ⁶ represents hydrogen, halogen, a lower alkyl group having 1 to 5 carbon atoms, an allyl group having 6 to 18 carbon atoms, or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms. Shows,
R ⁷ is an alkoxyl group or an acyloxyl group (wherein the alkoxyl group or the acyloxyl group may have a substituent containing oxygen or nitrogen), R ⁸ is hydrogen, halogen, or lower alkyl having 1 to 5 carbon atoms. Group, an allyl group having 6 to 18 carbon atoms or a lower alkyl group having 1 to 5 carbon atoms having an allyl group having 6 to 18 carbon atoms, and R ⁹ represents a lower alkyl group having 1 to 5 carbon atoms. Vinylsilane compound (X),
Specific compound names of (Y) and (Z) include, for example, vinyltrimethoxysilane, vinylethoxysilane, vinylmethyldimethoxysilane, and γ-methacryloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

Further, in the present invention, a composition obtained by blending 30 to 97% by weight of EVOH (A) or / and EVOH (A ') with 3 to 70% by weight of a vinylsilane compound-containing polyolefin (B) described later ( The use of C) is also one of the excellent aspects. If the blending ratio of the vinylsilane compound-containing polyolefin (B) is less than 3% by weight, the effect of improving the packaging appearance is not sufficient. On the other hand, the blend ratio is 70% by weight
If it exceeds, the gas barrier property is significantly deteriorated, which is not preferable. More preferably, it is 5 to 50% by weight. Also,
As EVOH to be used, EVOH (A ') has a greater effect of improving the packaging appearance than EVOH (A), and as a result, improvement of gas barrier properties can be expected by reducing the amount of resin (B) to be blended. . On the other hand, the resin (B) to be blended may be the same as or different from the resin (B) laminated with the EVOH layer, generally EVOH.
The resin (B) laminated with the layer is mainly composed of the above formulas (I) and (I
In order to satisfy I), it is selected by focusing on the resin brand, resin composition, vinylsilane content, presence or absence of catalyst, its type, and wet heat treatment conditions, but the resin (B) blended with EVOH is mainly a phase with EVOH. The resin (B) to be laminated and the resin (B) to be blended are often not the same because they are selected by paying attention to solubility and transparency.

Next, the vinylsilane-modified polyolefin (B) will be described. The resin (B) used in the present invention is a polyolefin obtained by copolymerizing or grafting a vinylsilane compound. As the vinylsilane-based compound, the compounds represented by the above-mentioned (X), (Y) and (Z) are suitable. More specifically, there are, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane and the like. It is also possible to use an unmodified polyolefin (which may be the same as or different from the silane modified polyolefin) in the silane modified polyolefin.

A method for obtaining such a silane-modified polyolefin (B) by copolymerization is disclosed in, for example, JP-A-55-9611. For example, when copolymerizing the vinylsilane compound with ethylene, the pressure is 500 to 4000 kg / cm. ² , temperature 100-40
The reaction is carried out simultaneously or stepwise in the reactor in the presence of a radical polymerization initiator and, if necessary, a chain transfer agent at 0 ° C. In this case, a third monomer such as vinyl acetate, acrylic acid, methacrylic acid and their esters may be copolymerized. On the other hand, as a method for imparting a silyl group by grafting, there is a method disclosed in JP-A-48-1711. For example, there is a method in which the above-mentioned vinylsilane compound and a radical generator are supplied to polyolefin and supplied to an extruder and extruded at a cylinder temperature of 180 to 240 ° C.
In this case, organic radicals such as dicumyl peroxide and benzoyl peroxide are preferable examples of the radical generator.

The content of the copolymerized or grafted vinyl silane compound of polyolefin is 0.005 to 5 mol%, preferably 0.0
It is 1 to 4 mol%, and more preferably 0.1 to 2 mol%.

When the content of the vinylsilane compound is less than 0.005 mol%, a product having a good packaging appearance cannot be obtained. On the other hand, when it is 5 mol% or more, gel and lumps frequently occur during film formation, and a product having a good packaging appearance cannot be obtained.

By the way, the silane-modified polyolefin (B) and EVOH
In a skin pack packaging in which a laminate composed of (A) and the like is used as a skin layer, in order to obtain a multilayer skin pack having a good appearance without crushing or wrinkling of the contents, the measuring temperature (T) is 60 ° C to 230 ° C as described above. It is an important requirement that the multilayer film satisfy the above formulas (I) to (II) in a tensile-recovery test at a temperature of ° C.

That is, the measurement temperature (T) is 60 to 230 ° C, and more preferably 80
-200 ℃, more preferably 100-140 ℃, the total layer thickness 50-500μ, preferably 100-200μ, width 15mm, check interval 500mm, pulling the film under the conditions of pulling and recovery speed 50mm / min It is measured with a tester (Ohgraph made by Shimadzu with a constant temperature bath). As the sample film to be used, it is most preferable to use a film before packaging with a skin pack, but a film after packaging may be used. First, 5-50%, preferably 10-40, for the check space (50 mm)
Immediately recover after applying% strain (t). F (kg / mm ² ) is the stress generated at the time of strain (t), residual strain after recovery {(before measurement, sample length at zero stress)-(after measurement, sample length at zero stress)} × 100 When ((sample length before measurement, zero stress)} is R (%), if F at the measurement temperature (T) is less than 0.0001t, the skin pack packaging temperature (T ± 20 ° C) will be Breakage and wrinkling after packaging are remarkable. Further, if it exceeds 0.01 t, the contents are crushed after packaging, which is not preferable in terms of packaging appearance. Preferably 0.00
It is from 05t to 0.0065t. On the other hand, R at the measured temperature (T) is 0.
If it exceeds 15 tons, wrinkling of the contents will be severe at the skin pack packaging temperature (T ± 20 ° C). It is preferably 0.13 t or less. Normally, R does not show a negative value, but there is a case where residual strain remains in the film during film formation and subsequent post-treatments, so that R becomes negative. At this time, before the measurement, it is necessary to heat-treat at the measurement temperature to alleviate the residual strain so that R does not become negative.

EVOH (A) {including (A ')} and composition (C) is F
Both the R value and the R value are large. Therefore, it is necessary to select a resin having a small F value and a small R value as much as possible for the resin (B) to be laminated. It is necessary to select a resin that has seemingly contradictory properties that the shrinkage stress is as large as possible. Regarding the F value, if the film thickness is constant, EVOH
The F values of (A) and composition (C) dominate, but EV
It is desirable that the thickness of the OH (A) layer be as thin as possible within the required limit level of gas barrier properties, and generally 2 to 40%, preferably 3 to 20% of the total film thickness.
%. Regarding the R value, on the other hand, the resin having a large shrinkage stress at the time of recovery after being pulled as the resin (B) is selected. However, a resin having a large shrinkage stress generally has a large F value, and the formula (I) is It is difficult to be satisfied. However,
Surprisingly, it has been found that some silane-modified polyolefins satisfy these seemingly contradictory properties. That is, when the silane modification amount in the polyolefin is increased step by step, the amount of the silane modification is affected by the type of polyolefin, but the range of 0.005 to 5 mol% of the silane modification is in the range immediately before gels and spots start to frequently occur during extrusion molding. Then, it was found that a resin (B) having the above characteristics was obtained. However, there is also a problem that the characteristics tend to fluctuate depending on the molding temperature, molding model, etc., so in order to improve this, the silane modification amount in the silane modified polyolefin should be as small as possible within the range of 0.005 to 5 mol%, 0.001 to 1 of dibutyltin laurate, dibutyltin diacetate, dioctyltin diacetate, dioctyltin dilaurate, cuprous acetate, inorganic acids, fatty acids, bases such as ethylamine and dibutylamine
It is preferable to blend 0% by weight, more preferably 0.01 to 1% by weight. Furthermore, in order to further increase the performance, the film after molding is subjected to wet heat treatment at 60 to 120 ° C., preferably in steam at 70 to 160 ° C. for 1 to 1000 seconds, preferably at 80 to 120 ° C. for 10 to 500 seconds. Is preferred.

Polyethylene, polypropylene, etc. may be used as the brand of the polyolefin which is the base material of the silane-modified polyolefin (B), but since the brand having a lower F value is generally more effective, the ethylene content is 3 to 40 mol%. Resins obtained by copolymerizing at least one of propylene, vinyl acetate, acrylic acid, methacrylic acid, and esters thereof are preferable. Among them, ethylene-propylene, ethylene-vinyl acetate and ethylene-acrylic acid ester (methyl ester, ethyl ester) are more preferable.

A sealant layer is preferably provided in the multilayer film of the present invention. As the sealant, polyethylene (PE), ethylene-propylene copolymer, polypropylene (PP), ethylene-vinyl acetate copolymer, ethylene-
Acrylic acid copolymers, ethylene-acrylic acid ester copolymers, ethylene-methacrylic acid copolymers, ethylene-methacrylic acid ester copolymers, ionomers and the like, among others, ethylene-vinyl acetate copolymer, Ionomer and the like are preferably used.

In the present invention, the EVOH (A) layer, the modified polyolefin resin (B), the EVOH (A) layer, the modified polyolefin resin (B) The adhesive is not particularly limited as long as it firmly adheres to the sealant layer, but an unsaturated carboxylic acid or its anhydride (maleic anhydride, etc.) is used as an olefin polymer or copolymer [polyethylene (low density). Polyethylene (LDPE), Linear low density polyethylene (LLDPE), Ultra low density polyethylene (SLDP)
E)}, ethylene-vinyl acetate copolymer, ethylene-
The (meth) acrylic acid ester (methyl ester or ethyl ester) copolymer] is preferably used.

As a method for obtaining the multilayer film of the present invention, the EVOH
Extrusion laminating method, dry laminating method, co-extrusion laminating method, co-extrusion sheet molding method, co-extrusion pipe molding method with (A), resin (B), etc., often via an adhesive resin,
Examples thereof include a method of obtaining a laminate by a co-injection molding method, a solution coating method and the like.

There is no particular limitation on the method of collecting and reusing the scraps such as trims and defective devices generated during molding. The scrub is crushed and, if it is hygroscopic, dried and then dry blended with the raw material resin (B), the crushed scrap is pelletized, and then dry blended with the raw material resin (B), and the crushed scrap is used. There is a method of making the raw material resin (B) into a blend pellet. The blending ratio of the raw material resin (B) and the scrap is not particularly limited, but is usually blended at a ratio of about 2 to 80%. At this time, in order to improve the dispersibility and heat stabilizer and to suppress abnormalities during molding (gel, lumps, streaks, opacity, etc.), maleic anhydride modified polyolefins, maleic anhydride modified olefin-styrene copolymers, It may be preferable to add one or more metal soaps, hydrotalcite-based compounds, and the like.

Further, with respect to the thickness configuration of the multilayer film, although not particularly limited, in consideration of moldability and cost, usually as the total layer thickness, 10 ~ 500μ, preferably 15 ~ 200μ, The thickness ratio of the EVOH (A) layer or the composition (C) layer to the total thickness is 2 to 40%, more preferably 3 to 30%. The thickness of the resin (B) layer is 3 to 90%, more preferably 5 to 60%.
The thickness ratio of the layer to the EVOH (A) layer or the composition (C) layer is one of the important factors for satisfying the above formulas (I) and (II). Therefore, it cannot be specified in any way, but resin (B) layer / EVOH
The layer (A) or the composition (C) layer has a thickness of 98/2 to 50/50. In addition, as the constitution of the multilayer film, EVOH (A) or (C) layer / adhesive resin layer / resin (B) layer, resin (B) layer / adhesive resin layer / EVOH (A) or (C) layer /
Adhesive resin layer / resin (B) layer, EVOH (A) or (C)
Layer / adhesive resin layer / collection layer, EVOH (A) or (C) layer / adhesive resin layer / collection layer / resin (B) layer, resin (B) layer / collection layer / adhesive resin layer / EVOH ( A) or (C) layer /
Adhesive resin layer / resin (B) layer, resin (B) layer / collection layer /
Adhesive resin layer / EVOH (A) or (C) layer / adhesive resin layer / collection layer / resin (B) layer, recovery layer / adhesive resin layer / EVO
H (A) or (C) layer / adhesive resin layer / resin (B)
Typical examples include a layer, a recovery layer / adhesive resin layer / EVOH (A) or (C) layer / adhesive resin layer / recovery layer. When the resin (B) layer is provided on both outer layers, the resins may be different or the same. Also,
It is common to provide a sealant layer on one surface (innermost layer or outermost layer) or both surfaces (innermost layer and outermost layer) of the above-mentioned multilayer film either directly or through an adhesive resin layer.

Next, the method of skin pack packaging will be described. The device used for skin pack packaging comprises a heating mold for molding (upper and / or lower mold), a decompression chamber, a heat sealer part, and optionally a preheating heater part and a steam shrink part.

First of all, the film or sheet that will be the lid material,
Alternatively, the contents are placed on the tray in a thermoformed state. Next, the film to be the skin layer is sent to the heating mold for molding directly or after passing through the preheating heater part heated to 40 to 250 ° C., preferably 60 to 150 ° C. . Here, the skin film is pressed by a vacuum or pressure to a heating mold for heating at 40 to 250 ° C., preferably 60 to 150 ° C. to be preformed. here,
As a more preferable temperature of the heating mold for molding, at the time of the film tension-recovery test described above, the measured temperature is in the vicinity of the measurement temperature T that satisfies the formulas (I) and (II), that is, T ± 20 ° C., and optimally T ±.
15 ° C.

Next, after covering the lid material on which the above-mentioned contents are placed with a skin layer pressed against a heating mold for molding, after heat-sealing the skin layer and the lid material under a reduced pressure state (in a reduced pressure chamber), Return to atmospheric pressure. By the way, when the temperature of the molding heating die is lower than the heat sealing temperature of the skin layer and the bottom material, change to a brand with a lower heat sealing temperature or use a heat sealer built-in skin pack packaging device that can set the temperature separately. To be

Then, the skin layer is brought into close contact with the surface of the contents by atmospheric pressure to obtain a skin pack. When returning from this vacuum state to atmospheric pressure, sending high-temperature steam (100 to 250 ° C) into the decompression chamber is effective in increasing the adhesion of the skin layer to the contents. Further, as described above, it is possible to prevent wrinkles, tears, uneven thickness, etc. due to uneven molding by allowing the film to pass through the preheating heater portion in advance before preforming the film for skin with the heating mold for molding. Is effective for.

As described above, the skin pack packaging is a film having improved properties when the multi-layer film is stretched / shrinked under heating, or stretched / cooled / heat-shrinked. Therefore, another molding process similar to this is performed. For example, it is effective for improving the heat shrinkability of the shrink-wrapping film, or for improving the heat-stretchability during the production of the shrink-wrapping film.

Hereinafter, more detailed description will be given with reference to Examples, but the present invention is not limited thereto.

E. Examples Example 1 70% by weight of EVOH (A) having an ethylene content of 44 mol%, a vinyltrimethoxysilane content of 0.012 mol% and a saponification degree of 99.5%, an ethylene content of 84 mol% and a vinylmethoxysilane content of 0.55. After dry blending with 30 parts by weight of a silane-modified ethylene-vinyl acetate copolymer (B) of mol%, pelletizing was performed at 180 ° C under 40φ extruder, N2, and dried under reduced pressure at 50 ° C-16 hours. , A composition (C) was obtained. Next, the composition (C), the resin (B), a maleic anhydride-modified ethylene-vinyl acetate copolymer (Admer VF600 manufactured by Mitsui Petrochemical Co., Ltd.) as an adhesive resin, and ethylene-
Resin (B) / adhesive resin / composition (C) / adhesive resin / using a vinyl acetate copolymer (Effectex EV-460 manufactured by Mitsui Polychemicals) using a 4-type 5-layer coextrusion film forming apparatus.
A multilayer film having a sealant structure was obtained. The thickness of the film at this time was 40/10/5/10 / 35μ, respectively. The film was passed through a 120 ° C. superheat steam bath for 10 seconds and then wound as a product.

In order to measure the characteristics of the film, it was cut into a width of 15 mm and a length of 10 cm, and a tensile tester with a thermostatic chamber (Shimadzu AG-500) was used.
The stress generated when the strain t = 20% in the test of recovering the strain t = 20% at a temperature T = 120 ° C. and a pulling speed of 100 mm / min using A) immediately after the strain t = 20%. Is F = 0.07 kg / mmm, and residual strain after recovery {(length before tension, stress F = 0)-(length after recovery, pressure F = 0) × 100 / (before tension , Length when stress F = 0)}
Was R = 3%. Moreover, when the oxygen transmission coefficient at 20 ° C-65% RH was measured (a measuring device manufactured by Mocon Co.), it was 4.5 cc.
It was 20 μ / m ² .day.atm.

Next, in order to evaluate the skin pack packaging suitability of the film, as a lid material, a film in which a polyethylene terephthalate (PET) film having a thickness of 100 μ and a 50 μ ethylene-vinyl acetate copolymer as a sealant layer are laminated,
Slice ham was used as the content, and the evaluation was performed using a skin pack packaging machine (manufactured by Multiback). The operating conditions of the skin pack packaging machine are molding speed 15
sec./shot, upper mold temperature was 120 ° C. The appearance of the obtained skin pack package was good without streaks, wrinkles and crushing.

Examples 2 to 6 and Comparative Examples 1 to 4 The conditions were the same as in Example 1 except that shown in Table 1. The results are shown in Table 1.

F. Effects of the Invention The multilayer film of the present invention is mainly used as a skin layer of a skin pack, and has good appearance quality after packaging, particularly good moldability, little wrinkles, and excellent gas barrier property.

Claims (3)

[Claims] 1. An ethylene content of 20 to 60 mol%, a saponification degree of 90.
% Or more of saponified ethylene-vinyl acetate copolymer (A)
Layer and at least two layers of the polyolefin (B) layer having a vinylsilane compound content of 0.005 to 5 mol% and having formulas (I) to (II) in a tensile-recovery test at a measurement temperature of 60 to 230 ° C. A multi-layer film that satisfies the requirements. 0.0001t ≤ F ≤ 0.01t (I) 0 ≤ R ≤ 0.15t (II) where, t: strain (5% ≤ t ≤ 50%) F: stress generated when strain t is applied (kg / mm ² ) R: Residual strain (%) when stress F = 0 immediately after applying stress F and strain t 2. The multilayer film according to claim 1, which has a heat seal layer. 3. A skin pack comprising the multilayer film according to claim 1 or 2.