JPH05124159A - Food packing stretched film - Google Patents

Abstract

PURPOSE:To provide the title film excellent in elongation characteristics, deformation recovery properties, packing machine aptitude and workability and having no problem from the aspect of disposal treatment and food sanitation. CONSTITUTION:In a laminated film having a three-layered structure, the surface layers on both sides of the film are composed of a composition (A) based on an ethylene/vinyl acetate copolymer and a saponified ethylene/vinyl acetate and consisting of 0.5-75wt.% of a vinyl acetate unit and 0.5-60wt.% of a vinyl alcohol unit. The center layer of the film is composed of a composition (B) based on an ethylene/vinyl acetate copolymer and a resin having an m.p. 15 deg.C higher than that of the copolymer and containing 0.5-25wt.% of a vinyl acetate unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch film for food packaging, and more particularly to a film obtained by laminating layers made of a specific composition,
The present invention relates to a stretch film for food packaging, which has excellent deformation recovery properties, and has no waste disposal property or food hygiene problems.

[0002]

2. Description of the Related Art Generally, a film for stretch-wrapping foods such as fruits and vegetables, fresh fish, fresh meat, and prepared foods directly or on a plastic tray is required to have the following characteristics. It (1) Gloss and transparency for improving product value (display effect) (2) Breathability and anti-fog property for maintaining freshness and display effect of food containing a lot of water (3) Preventing product drying Water vapor permeability for maintaining freshness (4) Self-adhesiveness for maintaining tight packaging (5) Uniform elongation for obtaining tight packaging and elongation characteristics for recovery (6) Stretch packaging work Suitability for packaging machines to improve reliability

Conventionally, a plasticized polyvinyl chloride film has been used as a film satisfying such characteristics. However, since the plasticized polyvinyl chloride film uses a large amount of plasticizer, it has a large water vapor permeability, and there is a problem that the plasticizer easily migrates to the packaged item. Also,
Since it has poor cold resistance, it has a drawback that when the package is stored at a low temperature, the film becomes hard and brittle and is easily broken.

Further, regarding the post-use treatment of the film, in the plasticized polyvinyl chloride film, the plasticizer tends to flow out from the film after disposal, and the plasticizer that flows out may pollute the sea or river. In addition, since hydrogen chloride gas is generated when incinerating at a garbage disposal site, a special treatment facility is required for the incinerator, and when incinerating at home, the toxic gas released is preferable for direct health. Furthermore, there was a problem that it contributed to the promotion of acid rain.

As a solution to these problems, the following polyolefin resin films have been proposed. A stretch packaging film obtained by laminating a layer containing a butene-1 resin as a main component and a layer containing an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 5 to 25% by weight as a main component (Japanese Patent Laid-Open No. 2000-242242). 61-89040). A random copolymer of propylene and at least one α-olefin selected from ethylene and α-olefins having 4 to 8 carbon atoms, wherein the α-olefin unit content is 4 to 19% by weight, and the melt Flow rate is 1 to 1
A layer containing an ethylene-vinyl acetate copolymer resin having a vinyl acetate unit content of 5 to 25% by weight as a main component was laminated on both surfaces of a layer containing a resin of 0 g / 10 minutes as a main component, and the thickness was 6
Stretch wrapping film having a thickness of -40 μm
1-444635). A layer made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 1 to 10% by weight and a layer made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 11 to 50% by weight. Stretch film for food packaging (JP-A-61-44635).

However, the conventional film described above does not have the uniform elongation property of the film, which is the most important as a stretch film, and the film described above has a temperature range that can be heat-sealed in an automatic packaging machine. Since it is narrow, there is a problem that the film other than the heat-sealed portion is melted to cause perforation. As described above, the films shown in the above and cannot sufficiently meet the characteristics required as a film for stretch packaging. As described above, at present, a stretch film for food packaging which satisfies the above-mentioned required characteristics and has no problems in waste disposal and food hygiene has not yet been proposed.

[0007]

Therefore, the present inventor has solved the problems of the conventional film described above, has a uniform elongation property of the film, and has a temperature range in which heat sealing in an automatic packaging machine is possible. We are keen to develop a stretch film that is wide and has excellent packaging workability, that fully satisfies the requirements for stretch wrapping of foods, and that does not cause environmental problems when used, and has no food hygiene problems. Repeated research. As a result, they have found that a laminate obtained by laminating layers made of a specific composition is a film suitable for the above purpose. The present invention has been completed based on such findings.

That is, the present invention is a laminated film having a three-layer structure, wherein the surface layers on both sides of the film are (A) an ethylene-vinyl acetate copolymer and a partially saponified ethylene-vinyl acetate copolymer. As the main component,
A central layer comprising a layer of a composition having a vinyl acetate unit content of 0.5 to 75% by weight and a vinyl alcohol unit content of 0.5 to 60% by weight (hereinafter sometimes referred to as layer (A)). Is mainly composed of (B) an ethylene-vinyl acetate copolymer and a resin having a melting point higher than that of the copolymer by 15 ° C. or more, and has a vinyl acetate unit content of 0.5 to 25% by weight.
The present invention provides a stretch film for food packaging, comprising a layer of the composition (hereinafter sometimes referred to as layer (B)).

The film of the present invention is basically a laminated film having a three-layer structure, the surface layers on both sides of which are (A) layers,
The central layer is the (B) layer. That is, the basic structure of the film of the present invention is (A) layer / (B) layer / (A) layer. The (A) layer in the present invention is mainly composed of an ethylene-vinyl acetate copolymer and an ethylene-vinyl acetate copolymer partially saponified product, and has a vinyl acetate unit content of 0.5 to 75.
It is a layer of a composition having a weight% and a vinyl alcohol unit content of 0.5 to 60% by weight. Here, the ethylene-vinyl acetate copolymer has a vinyl acetate unit content of 1.0 to
25% by weight, preferably 8 to 20% by weight, more preferably 12 to 20% by weight.

The partially saponified ethylene-vinyl acetate copolymer can be obtained by a conventional saponification treatment of an ethylene-vinyl acetate copolymer, for example, using a saponifying agent such as sodium hydroxide. It is a partially saponified product. The saponification-treated ethylene-vinyl acetate copolymer is not particularly limited, but it has a vinyl acetate unit content of 20 to 60% by weight, preferably 30 to 60% by weight. If the vinyl acetate unit content is less than 20% by weight, self-adhesiveness and deformation recovery cannot be sufficiently obtained even if optimization is attempted by adjusting the saponification degree, and the vinyl acetate unit content is 60% by weight. If the amount exceeds the above range, compatibility with an automatic packaging machine and sufficient stress at the time of pulling may not be obtained even if optimization is attempted by adjusting the degree of saponification.

Further, the saponification degree of the saponified product is usually 10-9.
It is 0%, preferably in the range of 30 to 60%. If the degree of saponification is less than 10%, an appropriate stress for elongation when the film is stretched and the effect of modifying the deformation recovery are insufficient,
If it exceeds 90%, the flexibility of the film may not be obtained depending on the situation.

The composition of the layer (A) of the present invention comprises the above components and has a vinyl acetate unit content of 0.5 to 75% by weight and a vinyl alcohol unit content of 0.5 to 60% by weight. Need to be in. When the vinyl acetate unit content of the composition is less than 0.5% by weight or more than 75% by weight, appropriate flexibility, self-adhesiveness and uniform elongation properties required for a stretch film are deteriorated, which is aimed at. I can't get a film. If the content of the vinyl alcohol unit is less than 0.5% by weight or exceeds 60% by weight, the breaking strength and deformation recovery properties required for the stretch film cannot be obtained, which is not practical.

The layer (A) is a layer containing the above-mentioned copolymer and partially saponified copolymer as a main component. The blending ratio of these is not particularly limited as long as the above physical properties are obtained, but the copolymer is 70% by weight or less, that is, the partially saponified copolymer is 30 to 100% by weight, preferably the copolymer. 50% by weight or less, that is, a partially saponified copolymer 50 to 1
A composition containing 100% by weight is preferable. If the content of the copolymer exceeds 70% by weight, that is, if the proportion of the partially saponified copolymer is less than 30% by weight, the flexibility, breaking strength, and deformation recovery of the film are deteriorated, and the uniform elongation property is obtained. Can't get

The layer (A), which is the surface layer of the film, is composed of a composition containing the above components as a main component, but other additives can be blended if necessary. Specifically, polyglycerin fatty acid ester can be added in order to obtain appropriate slipperiness, self-adhesiveness, antistatic property and antifogging property. Here, examples of the polyglycerin fatty acid ester include diglycerin laurate, diglycerin stearate, diglycerin oleate, tetraglycerin stearate, tetraglycerin oleate, hexaglycerin laurate, hexaglycerin oleate, decaglycerin laurate, decaglycerin. Examples thereof include stearate and decaglycerin oleate. The amount of polyglycerin fatty acid ester added is usually 0.
It is 1 to 5.0% by weight, preferably 0.5 to 3.0% by weight.
If the amount of polyglycerin fatty acid ester added is less than 0.1% by weight, the effect of modifying the film is insufficient, and the amount is 5.0% by weight.
If it exceeds, the amount of protrusion to the surface of the film is large, the film is sticky, and as a result, the workability is remarkably reduced, and problems such as contamination of the object to be packaged occur, which is not preferable.

Next, the (B) layer, which is the central layer in the film of the present invention, is mainly composed of an ethylene-vinyl acetate copolymer and a resin having a melting point higher by 15 ° C. or more than the melting point of the ethylene-vinyl acetate copolymer. It is a layer of a composition which, as a component, has a vinyl acetate unit content of 0.5 to 25 wt%.
As one component of the composition constituting the (B) layer, ethylene-
By blending a resin having a melting point higher than that of the vinyl acetate copolymer by 15 ° C. or more, the heat-sealable temperature range can be widened without impairing the uniform elongation property of the film, and the target film can be obtained. Is obtained.

The ethylene-vinyl acetate copolymer used in the composition of the layer (B) has a vinyl acetate unit content of 1.0 to 25.
% By weight, preferably 5 to 20% by weight, more preferably 8 to 18% by weight. The melting point of the ethylene-vinyl acetate copolymer varies depending on the vinyl acetate unit content and the like, but is usually in the range of 80 to 100 ° C., and as a resin having a melting point of 15 ° C. or higher than this copolymer,
There are no particular restrictions on the resin that satisfies this condition, but polypropylene, low-density polyethylene, polybutene-1 and the like can be mentioned, and these resins can be used alone or in combination of two or more.

The polypropylene that can be used here may be a crystalline polypropylene produced by a conventionally known method or a copolymer with another resin unit. In particular, an ethylene-propylene random copolymer having an ethylene unit content of 4 to 15% by weight is suitable. The physical properties are not particularly limited, but those having a melt flow rate at 230 ° C. of 1.0 to 15 g / 10 minutes are preferable. The melting point varies depending on the content of other resin units, but is usually 110
It is 170 ° C.

The low-density polyethylene may be either an ethylene homopolymer or a copolymer with another resin unit, but especially an ethylene unit and a carbon number of 4 to 4.
A linear low-density polyethylene which is a copolymer of 12 α-olefins is suitable. Regarding the physical properties, the density is 0.900 to 0.940 g / cm ² , and more preferably,
It is 0.900 to 0.920 g / cm ² , and the melt flow rate at 190 ° C. is 0.5 to 15 g / 10 minutes, preferably 0.5 to 8 g / 10 minutes. The melting point varies depending on the density, but is usually 100 to 130 ° C.

Further, as polybutene-1, butene-
It may be a homopolymer or a copolymer with another resin unit. Particularly, a butene-1-ethylene copolymer having an ethylene unit content of 1.5 to 10% by weight is preferable. The physical properties are not particularly limited, but the density is 0.890 to 0.920 g.
/ Cm ² , and the melt flow rate at 190 ° C is 0.
Those having 1 to 10 g / 10 minutes are particularly preferable. The melting point varies depending on the content of other resin units, but is usually 100 to 126.
℃.

The composition of the layer (B) of the present invention contains the above-mentioned copolymer and resin as main components, but the vinyl acetate unit content of the composition is 0.5 to 25% by weight, It is preferably 4 to 18% by weight. Here, if the vinyl acetate unit content is less than 0.5% by weight or more than 25% by weight, uniform elongation characteristics cannot be obtained in the film, which is not preferable.

In the composition of the layer (B), there is no particular limitation on the blending ratio of the above-mentioned copolymer and resin (that is, a resin having a melting point higher by 15 ° C. or more than the ethylene-vinyl acetate copolymer). The ethylene-vinyl acetate copolymer is usually 50 to 90% by weight, preferably 60 to 85% by weight, though it may be appropriately selected within the range satisfying the above conditions.
And Here, when the copolymer is less than 50% by weight, that is, when the resin exceeds 50% by weight, uniform elongation properties of the obtained film cannot be obtained, and when it exceeds 90% by weight, that is, the resin is If it is less than 10% by weight, the effect of improving the heat sealing property cannot be expected.

The film of the present invention is a film having a three-layer structure in which the above-mentioned (A) layer is a surface layer on both sides and the (B) layer is a center layer, and the surface layers on both sides of the (A) layer are: The same composition may be used, or a composition belonging to the category of the above composition but having a different component composition may be used. As a method for producing such a laminated film, the above-mentioned respective compositions can be laminated by a conventional method, specifically, an inflation method, a T-die method, an extrusion laminating method or the like. Of these, the inflation method is preferable because it has a good balance of physical properties in the vertical and horizontal directions.

The thickness of the laminated film of the present invention is not particularly limited, but is usually 8 to 20 μm, preferably 10 to 1
It is 5 μm. If the thickness of the film is less than 8 μm, the handleability of the film is significantly deteriorated due to the deterioration of the strength and stiffness of the film, and if it exceeds 20 μm, the stress at the time of pulling the film becomes large and the packaged object is deformed. Happens.

Further, the thickness of the center layer of the film is 1.0 to 1.
The thickness is preferably 2.0 μm, preferably 2.0 to 8.0 μm. Here, if it is less than 1.0 μm, the effect of improving the heat-sealing property cannot be expected, and if it exceeds 12.0 μm, uniform elongation properties may be impaired.

【Example】

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 40% by weight, melt flow rate at 190 ° C. 2.
800 g of toluene-methanol mixed solvent (mixing ratio, toluene: methanol = 1: 1)
Dissolve in, add 3.3% methanol solution of sodium hydroxide as a saponifying agent, stir at 60 ° C for 2 hours, add acetic acid to neutralize when the degree of saponification reaches 60%, and further add water. Emulsion, then 400 ml of methanol
Was added to cause precipitation. After washing with methanol, it was dried to obtain a partially saponified ethylene-vinyl acetate copolymer.

Next, 49 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes), ethylene-vinyl acetate copolymer part obtained above 49 parts by weight of a saponified product and 2.0 parts by weight of diglycerin monooleate were mixed to form a composition, which was then pelletized to obtain a surface layer composition (composition 1).

Next, 80 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) and a propylene-ethylene random copolymer (containing ethylene unit: 7% by weight, melt flow rate at 230 ° C 2.
0 g / 10 minutes) 20 parts by weight to form a composition,
Pelletizing gave a composition for the central layer (composition 2).

Using the composition thus obtained, two extruders (bore diameter 50 mm, L / D = 26) were used so that the composition 1 was the central layer and the composition 1 was the surface layers on both sides of the composition 2. Then, a film was formed by an inflation method under the conditions of a resin temperature of 170 to 180 ° C. and a blow-up ratio of 3.8 to obtain a film having a thickness of each layer of 2 μm / 8 μm / 2 μm and a total thickness of 12 μm.

Using this film, meat, fish, prepared foods and fruits were placed on a tray made of expanded polystyrene and packaged by a stretch automatic packaging machine. The properties of the film and the measurement results are shown in Table 1.

The physical properties of each item were measured and evaluated by the following methods. 1) Melt flow rate; JIS K6760 2) Haze; JIS K6714 3) Breaking strength; JIS Z1702 4) Elongation; JIS Z1702 5) Deformation recoverability; Then, after 30 seconds, the length of the sample piece was measured, and the length returned by the sample piece was shown. 6) Self-adhesive force: Two 100 mm wide sample pieces were superposed, each end was fixed, and peeled in the vertical direction for measurement. 7) Elongation property: It was examined whether or not necking occurred when the film was stretched. 8) Anti-fog property: 100 ml of water at 20 ° C in a 300 ml beaker
When 5 ml was put and covered with a film and stored in a refrigerator at 1 ° C., the degree of cloudiness of the film was visually evaluated on a scale of 5 (the best was 5). 9) Heat seal temperature range: The heater temperature of the hot plate of the automatic packaging machine is set to 50 to 160 ° C., the stretch-wrapped tray is allowed to stand on the hot plate for a few seconds, and the seal strength at the bottom of the tray and the presence or absence of perforation It was evaluated and shown in the temperature range in which good sealing was possible. 10) Suitability for automatic wrapping machine: It was judged whether or not stretch wrapping is possible without problems such as wrinkles, cracking or distortion of tray, feeding property of film, and cutting property. 11) The degree of saponification was determined from the IR spectrum of the film by 3
It was performed by measuring the absorbance ratio of the absorption of the absorption and 720 cm ^-1 methylene group of the hydroxyl group of 350 cm ^-1.

Example 2 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 45% by weight, melt flow rate at 190 ° C. 5 g
/ 10 minutes) by the same method as in Example 1 with 1.
As a methanol solution of 7% sodium hydroxide, saponification was performed to obtain a partially saponified ethylene-vinyl acetate copolymer having a saponification degree of 45%.

Next, 39 parts by weight of an ethylene-vinyl acetate copolymer (content of vinyl acetate unit: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes), 39 parts by weight of the ethylene-vinyl acetate copolymer obtained above. 59 parts by weight of the combined partial saponified product and 2.0 parts by weight of diglycerin monooleate were mixed to form a composition, which was then pelletized to obtain a surface layer composition (composition 1).

Next, 80 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) and polybutene-1 (density: 0.908 g / cm ²⁾ , Melt flow rate at 190 ° C. (2.0 g / 10 minutes) to prepare a composition by mixing 20 parts by weight and pelletizing to obtain a composition for the central layer (composition 2).

The composition thus obtained was treated in the same manner as in Example 1 so that the thickness of each layer was 4 μm / 4 μm / 4 μ.
A film having a thickness of m and a total thickness of 12 μm was obtained.

This film was used for packaging. The properties of the film and the measurement results are shown in Table 1. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

Example 3 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 50% by weight, melt flow rate at 190 ° C. 5 g
/ 10 minutes) was saponified by the same method as in Example 1 to obtain a partially saponified ethylene-vinyl acetate copolymer having a saponification degree of 60%. Next, 49 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes), partially saponified ethylene-vinyl acetate copolymer obtained above 49 parts by weight of the product and 2.0 parts by weight of diglycerin monooleate were mixed to form a composition, which was then pelletized to obtain a surface layer composition (composition 1).

Next, 80 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) and linear low density polyethylene (ethylene and 1-hexene) were used. 20 parts by weight of a copolymer of the above, a density of 0.917 g / cm ² , and a melt flow rate at 190 ° C. of 0.8 g / 10 minutes) were mixed to form a composition, and then pelletized (composition 2).

The composition thus obtained was treated in the same manner as in Example 1 so that the thickness of each layer was 4 μm / 4 μm / 4 μ.
A film having a thickness of m and a total thickness of 12 μm was obtained. This film was used for packaging. The properties of the film and the measurement results are shown in Table 1. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

Comparative Example 1 30 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) as a central layer, polybutene-1 (density: 0. 908 g / cm ² , melt flow rate at 190 ° C. 2.0 g / 10 min) 70 parts by weight of a resin composition, and the surface layers on both sides were ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, Example 1 as a melt flow rate at 190 ° C. of 2.0 g / 10 minutes)
The film thickness is 4 μm / 4 μm by the same method as
A film having a thickness of / 4 μm and a total thickness of 12 μm was obtained. The film was used for packaging. The properties of the film and the measurement results are shown in Table 1. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

Comparative Example 2 An ethylene-vinyl acetate copolymer was used as the central layer (vinyl acetate unit content: 5% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 min), and both surface layers were made of an ethylene-vinyl acetate copolymer. Polymer (vinyl acetate unit content 18% by weight,
Melt flow rate at 190 ° C: 2.0 g / 10 minutes)
A resin composition consisting of 98 parts by weight and 2 parts by weight of sorbitan stearate was formed into a film in the same manner as in Example 1,
The thickness of each layer is 4μm / 4μm / 4μm, the total thickness is 12
A film of μm was obtained. The film was used for packaging. The properties of the film and the measurement results are shown in Table 1. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

Comparative Example 3 A commercially available plasticized polyvinyl chloride stretch film (thickness: 15 μm) was used to perform packaging in the same automatic stretch wrapping machine as in Example 1. First, the physical properties and results of the film
Shown in the table. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

[0042]

[Table 1]

[0043]

INDUSTRIAL APPLICABILITY As described above, the stretch film for food packaging of the present invention has uniform elongation characteristics when the film is stretched, is excellent in heat sealability in an automatic packaging machine, and has sufficient elongation and deformation. It has recoverability, suitability for packaging machines, and excellent workability. In addition, the gloss and transparency required for stretch films for food packaging,
It has good physical properties such as breathability, anti-fog property, water vapor permeability, and self-adhesiveness. Further, there is no problem of disposability after disposal like conventional plasticized polyvinyl chloride stretch films, and there is no problem in food hygiene at all. Therefore, the stretch film for food packaging of the present invention is expected to be widely used as a film for stretch-wrapping various foods such as fruits and vegetables, fresh fish, fresh meat, and prepared foods.

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

[Procedure amendment]

[Submission date] March 18, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

As a solution to these problems, the following polyolefin resin films have been proposed. A stretch packaging film obtained by laminating a layer containing a butene-1 resin as a main component and a layer containing an ethylene-vinyl acetate copolymer resin having a vinyl acetate content of 5 to 25% by weight as a main component (Japanese Patent Laid-Open No. 2000-242242). 61-89040). A random copolymer of propylene and at least one α-olefin selected from ethylene and α-olefins having 4 to 8 carbon atoms, wherein the α-olefin unit content is 4 to 19% by weight, and the melt Flow rate is 1 to 1
A layer containing an ethylene-vinyl acetate copolymer resin having a vinyl acetate unit content of 5 to 25% by weight as a main component was laminated on both surfaces of a layer containing a resin of 0 g / 10 minutes as a main component, and the thickness was 6
Stretch wrapping film having a thickness of -40 μm
1-444635). A layer made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 1 to 10% by weight and a layer made of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 11 to 50% by weight. Stretch film for food packaging (JP-A-55-81155).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

The low-density polyethylene may be either an ethylene homopolymer or a copolymer with another resin unit, but especially an ethylene unit and a carbon number of 4 to 4.
A linear low-density polyethylene which is a copolymer of 12 α-olefins is suitable. Regarding the physical properties, the density is 0.900 to 0.940 g / cm ³ , and more preferably,
It is 0.900 to 0.920 g / cm ³ , and the melt flow rate at 190 ° C. is 0.5 to 15 g / 10 minutes, preferably 0.5 to 8 g / 10 minutes. The melting point varies depending on the density, but is usually 100 to 130 ° C.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

Further, as polybutene-1, butene-
It may be a homopolymer or a copolymer with another resin unit. Particularly, a butene-1-ethylene copolymer having an ethylene unit content of 1.5 to 10% by weight is preferable. The physical properties are not particularly limited, but the density is 0.890 to 0.920 g.
/ Cm ³ , and the melt flow rate at 190 ° C is 0.
Those having 1 to 10 g / 10 minutes are particularly preferable. The melting point varies depending on the content of other resin units, but is usually 100 to 126.
℃.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

The physical properties of each item were measured and evaluated by the following methods. 1) Melt flow rate; JIS K6760 2) Haze; JIS K6714 3) Breaking strength; JIS Z1702 4) Elongation; JIS Z1702 5) Deformation recoverability; Then, after 30 seconds, the length of the sample piece was measured, and the length returned by the sample piece was shown. 6) Self-adhesiveness: Two 100 mm wide sample pieces were superposed, each end was fixed, and peeled in the vertical direction for measurement. 7) Elongation property: It was examined whether or not necking occurred when the film was stretched. 8) Anti-fog property: 100 ml of water at 20 ° C in a 300 ml beaker
When 5 ml was put and covered with a film and stored in a refrigerator at 1 ° C., the degree of cloudiness of the film was visually evaluated on a scale of 5 (the best was 5). 9) Heat seal temperature range: The heater temperature of the hot plate of the automatic packaging machine is set to 50 to 160 ° C., the stretch-wrapped tray is allowed to stand on the hot plate for a few seconds, and the seal strength at the bottom of the tray and the presence or absence of perforation It was evaluated and shown in the temperature range in which good sealing was possible. 10) Suitability for automatic wrapping machine: It was judged whether or not stretch wrapping is possible without problems such as wrinkles, cracking or distortion of tray, feeding property of film, and cutting property. 11) The degree of saponification was determined from the IR spectrum of the film by 3
It was performed by measuring the absorbance ratio of the absorption of the absorption and 720 cm ^-1 methylene group of the hydroxyl group of 350 cm ^-1.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

Next, 80 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) and polybutene-1 (density: 0.908 g / cm ^3). , Melt flow rate at 190 ° C. (2.0 g / 10 minutes) to prepare a composition by mixing 20 parts by weight and pelletizing to obtain a composition for the central layer (composition 2).

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

Next, 80 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) and linear low density polyethylene (ethylene and 1-hexene) were used. And a density of 0.917 g / cm ³ , and a melt flow rate at 190 ° C. of 0.8 g / 10 min) were mixed to prepare a composition, and then pelletized (composition 2).

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

Comparative Example 1 30 parts by weight of an ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0 g / 10 minutes) as a central layer, polybutene-1 (density: 0. 908 g / cm ³ , melt flow rate at 190 ° C. 2.0 g / 10 min) 70 parts by weight of a resin composition, and the surface layers on both sides are ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, Example 1 as a melt flow rate at 190 ° C. of 2.0 g / 10 minutes)
The film thickness is 4 μm / 4 μm by the same method as
A film having a thickness of / 4 μm and a total thickness of 12 μm was obtained. The film was used for packaging. The properties of the film and the measurement results are shown in Table 1. The physical properties of each item were measured and evaluated in the same manner as in Example 1.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

[0043]

INDUSTRIAL APPLICABILITY As described above, the stretch film for food packaging of the present invention has uniform elongation characteristics when the film is stretched, is excellent in heat sealability in an automatic packaging machine, and has sufficient elongation and deformation. It has recoverability, suitability for packaging machines, and excellent workability. In addition, the gloss and transparency required for stretch films for food packaging,
It has good physical properties such as breathability, anti-fog property, water vapor permeability, and self-adhesiveness. Further, there is no problem of disposability after disposal like conventional plasticized polyvinyl chloride stretch films, and there is no problem in food hygiene at all. Therefore, the stretch film for food packaging of the present invention is expected to be widely used as a film for stretch-wrapping various foods such as fruits and vegetables, fresh fish, fresh meat, and prepared foods.

Claims (6)

[Claims] 1. A laminated film having a three-layer structure, comprising:
The surface layers on both sides of the film are mainly composed of (A) ethylene-vinyl acetate copolymer and ethylene-vinyl acetate copolymer partially saponified product, and the vinyl acetate unit content is 0.
5-75% by weight, vinyl alcohol unit content is 0.5-
60% by weight of the composition layer, the central layer (B)
From a layer of a composition comprising an ethylene-vinyl acetate copolymer and a resin having a melting point higher than that of the copolymer by 15 ° C. or more as a main component and a vinyl acetate unit content of 0.5 to 25% by weight. Stretch film for food packaging characterized by: 2. The surface layer of either one of the films,
(A) 70% by weight or less of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 1.0 to 25% by weight and 10% of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 20 to 60% by weight. ~ 90% saponified ethylene-vinyl acetate copolymer partially saponified 30% by weight or more is the main component, and the vinyl acetate unit content is 0.5 to 7
The stretch film for food packaging according to claim 1, which is a layer of a composition having 5% by weight and a vinyl alcohol unit content of 0.5 to 60% by weight. 3. The center layer of the film comprises 50 to 90 parts by weight of (B) an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 1.0 to 25% by weight and a melting point of 15 from the copolymer.
The main component is a mixture of 10 to 50 parts by weight of a resin having a melting point higher than 0 ° C, and a vinyl acetate unit content of 0.
The stretch film for food packaging according to claim 1, which is a layer of the composition of 5 to 25% by weight. 4. The resin having a melting point higher than that of the ethylene-vinyl acetate copolymer by 15 ° C. or more in the center layer of the film is at least one polymer selected from polypropylene, low density polyethylene and polybutene-1. The stretch film for food packaging according to claim 1 or 3. 5. The total thickness of the film is 8 to 20 μm,
The stretch film for food packaging according to claim 1, wherein the thickness of the central layer is 1.0 to 12.0 µm. 6. The stretch film for food packaging according to claim 1, wherein one surface layer of the film contains the polyglycerin fatty acid ester in the range of 0.1 to 5.0% by weight.