JP3224290B2 - Stretch film for food packaging - Google Patents

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 in which a layer composed of a specific composition is laminated.
The present invention relates to a stretch film for food packaging which has excellent elongation properties, heat sealability, deformation recovery properties, and the like, and has no problems in disposal property and food hygiene.

[0002]

2. Description of the Related Art In general, the following properties are required for a film in which foods such as fruits and vegetables, fresh fish, fresh meat, prepared foods and the like are stretch-packed directly or on a plastic tray. (1) Transparency, gloss, and transparency for improving commercial value (display effect) (2) Breathability and anti-fogging properties for maintaining freshness and displaying effect of foods containing much moisture (3) Product Water vapor permeability for preventing drying and maintaining freshness (4) Self-adhesiveness and heat sealing properties for maintaining tight packaging (5) Uniform elongation for obtaining tight packaging and elongation properties for recoverability (6) Suitability of packaging machine for improving workability of stretch packaging

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 a plasticizer, there is a problem that the water vapor permeability is large and the plasticizer easily migrates to the package. Also,
When the package is stored at a low temperature due to poor cold resistance, there is a disadvantage that the film is hard and brittle and easily broken.

[0004] Further, with respect to post-use processing of the film, the plasticized polyvinyl chloride film tends to cause the plasticizer to flow out of the film after being discarded, and the plasticizer that has flowed out may contaminate the sea or river. In addition, when incinerated at a garbage disposal site, hydrogen chloride gas is generated, so special treatment equipment is required for the incinerator.When incinerated at home, the released toxic gas is directly preferable to health. In addition, there is a problem that it contributes to promotion of acid rain.

As a composition suitable for a stretch film which solves these problems, a composition described in Japanese Patent Publication No. 59-38976 has been proposed. However, in the case of this composition, the most important transparency, gloss and transparency are not sufficient in the inflation method which is a conventionally known film forming method, and are not at a satisfactory level.
Also, the packaging workability is not sufficient. Further, JP-A-63-
No. 41550 has been proposed, but this composition satisfies several points required for a stretch film only by stretching, but the elongation and deformation when the most important film is stretched. The properties that are less recoverable and required as a stretch film are
It is far apart. Also, as a film,
Japanese Patent Publication No. 2-52624 has been proposed. However, since this film is also a stretched film, it has little elongation and deformation recovery when the most important film is stretched, and has the properties required as a stretch film. Are far apart.

Further, a layer composed of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 1 to 10% by weight, and a layer composed of an ethylene-vinyl acetate copolymer having a vinyl acetate unit content of 11 to 50% by weight. (Japanese Patent Laid-Open Publication No. 55-8 / 78).
No. 1155). However, for this food packaging film, there is still a problem that the temperature range in which heat sealing can be performed by an automatic packaging machine is narrow, so that a film other than the heat sealing portion is melted and perforated.
In addition, there is a problem that the cutting property of the film by the cutter blade in the automatic packaging machine, the slipperiness with the tray or the article to be packaged, and the rubber-like elasticity are inferior to the automatic packaging machine.

[0007] Further, ethylene and α-
A random copolymer of at least one α-olefin selected from olefins and propylene,
An ethylene having a vinyl acetate unit content of 5 to 25% by weight on both surfaces of a layer mainly containing a resin having an olefin unit content of 4 to 19% by weight and a melt flow rate of 1 to 10 g / 10 minutes; A stretch packaging film having a total thickness of 6 to 40 μm, in which a layer mainly composed of a vinyl acetate copolymer resin is laminated (JP-A-61-446).
No. 35). However, this film for stretch packaging is inferior in transparency and gloss of the film, in particular, it is difficult to balance the physical properties of the film in the vertical and horizontal directions, is inferior in cutting properties, and does not have sufficient uniform elongation characteristics.

Further, the layer containing butene-1 resin as a main component has an ethylene-based resin having a vinyl acetate content of 5 to 25% by weight.
There has been proposed a film for stretch packaging in which a layer mainly composed of a vinyl acetate copolymer resin is laminated (see JP-A-61-89040). However, this stretch packaging film has relatively good vertical and horizontal balance of physical properties of the film, but is inferior in transparency and gloss, particularly transparency and uniform elongation characteristics of the film.

As described above, many stretch packaging films have been proposed. However, a stretch film for food packaging that satisfies the above-mentioned required characteristics and has no problem in disposal treatment and food hygiene has not yet been proposed. Is the current situation.

[0010]

An object of the present invention is to provide excellent transparency, gloss, transparency, elongation characteristics, deformation recovery, suitability for packaging machines, workability, etc., and problems in disposal and food hygiene. The object of the present invention is to provide a stretch film for food packaging.

[0011]

SUMMARY OF THE INVENTION The present inventor has solved the above-mentioned problems of the conventional film, has uniform elongation characteristics of the film, and is excellent in transparency, gloss, and transparency. The heat sealable temperature range is wide enough and the packaging workability is excellent, and it also satisfies the requirements for the stretch packaging property of foods, and furthermore, it does not cause environmental problems in the processing after use, and it is a problem in food hygiene. We continued our research to develop a stretch film without any. As a result, they have found that a laminated film having a layer composed of a specific composition is a film that meets the above-mentioned object.
The present invention has been completed based on such findings.

That is, the invention according to claim 1 is a laminated film having at least a three-layer structure, wherein the surface layers (layer A) on both sides of the film have a content of a monomer other than ethylene of 5 to 25. vinyl acetate copolymers, et styrene - - ethylene weight percent acrylic acid copolymer, ethylene - methacrylic acid copolymer, comprising at least one ethylene copolymer selected from among a ionomer resin, The layer (layer B) on the center side from the surface layer (layer A) is a melt flow
Crystalline polypropylene (B ₁ ) having a rate of 0.1 to 30 g / 10 min , ethylene and carbon number of 4 to 12
At least one α selected from α-olefins
- a copolymer of olefin and propylene, alpha-olefin content copolymers is 10 wt% to 30 wt% (B ₂₎ Do the compositions and Ri, the center-side layer
Crystalline polypropylene in the composition constituting (B layer)
(B ₁₎ the content of which is provided a food packaging stretch film according to claim der <br/> Rukoto 10 wt% to 50 wt% or less. The invention according to claim 4 has a small
A laminated film having at least a three-layer structure,
The surface layer (A layer) on both sides of the LUM is a monomer other than ethylene
-Vinyl acetate having a content of 5 to 25% by weight
Copolymer, ethylene-ethyl acrylate copolymer, ethyl
Len-methyl acrylate copolymer, ethylene-acryl
Acid copolymer, ethylene-methacrylic acid copolymer, ethylene
Len-methyl methacrylate copolymer, ethylene-meth
Ethyl acrylate copolymer, ionomer resin
From at least one selected ethylene copolymer
The layer (B layer) closer to the center than the surface layer (A layer)
Crystalline polypropylene (B ₁ ), ethylene and carbon number
Is at least one selected from among 4 to 12 α-olefins.
Is also a kind of copolymer of α-olefin and propylene.
The content of α-olefin is 10% by weight or more and 30% by weight
% Of the copolymer (B ₂ )
A copolymer of ten-1 and ethylene, wherein propylene
Or the butene-1 content is 10% by weight or more and 50% by weight.
Less than the copolymer (B ₃ ).
Provide a stretch film for food packaging
It is.

The stretch film for food packaging of the present invention is a laminated film having at least a three-layer structure, wherein the surface layers on both sides are (A layer), and the layer on the center side of the (A layer) layer is (B layer). ). That is, the basic structure of the stretch film for food packaging of the present invention is (A layer) / (B layer)
/ (A layer), but a plurality of layers may be provided between (A layer) and (B layer) or between (B layer).

The ethylene copolymer used in the surface layer (layer A ) according to the first aspect of the present invention is an ethylene-vinyl acetate copolymer having a monomer content other than ethylene of 5 to 25% by weight. coalescence, et styrene - acrylic acid copolymer, ethylene - methacrylic acid copolymer, Ru least one polymer der selected from among a ionomer resin. Claim 4
Used in the surface layer (A layer) in the invention according to
In the copolymer, the content of monomers other than ethylene is 5 to 5.
25% by weight of ethylene-vinyl acetate copolymer,
Len-ethyl acrylate copolymer, ethylene-acryl
Acid methyl copolymer, ethylene-acrylic acid copolymer, d
Tylene-methacrylic acid copolymer, ethylene-methacrylic acid
Methyl acrylate copolymer, ethylene-ethyl methacrylate
Selected from among copolymers and ionomer resins
Both are a kind of polymer. Among them, ethylene-vinyl acetate copolymer is most preferred. The content of the monomer other than ethylene is more preferably 7 to 25% by weight, further preferably 10 to 20% by weight. If the content of the monomer other than ethylene is less than 5% by weight, the sealing property, the transparency,
There is a possibility that sufficient flexibility or the like may not be obtained, and if it exceeds 25% by weight, strength properties may be reduced and blocking may occur.

Further, the ethylene copolymer constituting the surface layer (layer A) has a melt flow rate at 190 ° C. of preferably 0.1 to 10 g / 10 min, more preferably 0.5 to 10 g / 10 min.
５5 g / 10 min. This melt flow rate is
If the amount is less than 0.1 g / 10 minutes, there is a possibility that there is a problem in extrudability. If the amount exceeds 10 g / 10 minutes, there is a possibility that strength properties are reduced and molding stability cannot be obtained.

The surface layer (A layer) in the present invention can use the above resin alone or as a composition of two or more kinds.
The surface layer (A layer) in the present invention is composed of the above-mentioned resin composition. Further, in order to obtain appropriate slip properties, self-adhesive properties, antistatic properties, and antifogging properties, additives are required. Can be blended. Specifically, sorbitan monooleate such as sorbitan fatty acid ester, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan monolaurate, sorbitan monobehenate, sorbitan monostearate, glycerin monooleate, glycerin monostearate, glycerin monolaurate Rate, glycerin monobehenate, diglycerin monolaurate, diglycerin monostearate, diglycerin monooleate, tetraglycerin monooleate, tetraglycerin monostearate, hexaglycerin monolaurate,
Examples include, but are not limited to, hexaglycerin monooleate, decaglycerin monolaurate, decaglycerin monostearate, decaglycerin monooleate, and the like. These fatty acid esters may be used alone or as a mixed composition.
Usually 0.1 to 5.0% by weight, preferably 0.5 to 3.0%.
% By weight. If the addition amount is less than 0.1% by weight, the effect of modifying the film is not sufficient. If the addition amount exceeds 5.0% by weight, the amount of protrusion on the film surface is large, and the film is sticky. In addition to the above, there is a possibility that problems such as contamination of the packaged object may occur.

Next, the layer (layer B) closer to the center than the surface layer (layer A) was selected from crystalline polypropylene (B ₁ ), ethylene and α-olefins having 4 to 12 carbon atoms. It is a copolymer of at least one type of α-olefin and propylene, and a copolymer (B ₂ ) having a content of α-olefin of 10% by weight or more and 30% by weight or less.

The first component, crystalline polypropylene (B
₁ ) is a copolymer with polypropylene or another resin unit produced by a conventionally known method, and has a melt flow rate at 230 ° C. of 0.1 to 30 g / 10 min, preferably 0.2 to 15 g. / 10 min, more preferably 0.5
~ 3.0 g / 10 min. If the melt flow rate at 230 ° C. is less than 0.1 g / 10 minutes, there is a problem in molding stability, and if it exceeds 30 g / 10 minutes, the strength of the film is insufficient and there is a problem in molding stability. Further, (B ₁ ) is preferably ethylene and carbon number 4-1.
2 is a copolymer of at least one α-olefin selected from α-olefins and propylene, and more preferably a copolymer of ethylene or butene-1 and propylene. Here, the content of the α-olefin is 10% by weight or less, preferably 2% by weight or more and 10% by weight or less, more preferably 4% by weight or more and 8% by weight or less. When the content of the α-olefin exceeds 10% by weight, the temperature range in which heat sealing can be performed in an automatic packaging machine is narrowed, and the heat sealing property may be deteriorated.

The first component, crystalline polypropylene (B
₁ ) plays an important role in solving the problem that holes are formed by melting at the time of heat sealing in an automatic packaging machine, and in a specific range to prevent uneven stretching during stretching. It is important to mix. That is, the content of the crystalline polypropylene (B ₁ ) in the composition constituting the central layer (layer B) depends on other components, but is preferably 10% by weight or more and 50% by weight or less, more preferably. 30% by weight or more and 50% by weight or less. If the content of the crystalline polypropylene (B ₁ ) is less than 10% by weight, the effect of improving the heat sealing property may not be sufficiently obtained, and the appropriate temperature range in which the heat sealing can be performed is narrow. In the case of heat sealing with a hot plate etc., there is a problem that the film is partially melted and a hole is created.To prevent this, change the temperature conditions as the weight of the contents changes. It is inevitable, and the workability may be significantly reduced. On the other hand, if the content exceeds 50% by weight, the elongation characteristics of the film are reduced, the tray is deformed during the stretch packaging, and there is a problem that a tight package cannot be obtained. There is a risk of causing wrinkling in the package due to excessive elongation.

Next, the copolymer (B ₂ ) as the second component is
It is a copolymer of ethylene and at least one α-olefin selected from among α-olefins having 4 to 12 carbon atoms and propylene. The α-olefin used here includes butene-1, hexene-1, heptene-
1,4-methyl-1-pentene, octene-1 and the like. The α-olefin content of the copolymer (B ₂ ) is 1
0 wt% or more and 30 wt% or less, preferably 12 wt% or more and 20 wt% or less. If the content of α-olefin is less than 10% by weight, the film may not have sufficient deformation recovery properties and elongation properties. If it exceeds 30% by weight, the appropriate temperature range for heat sealing is narrowed. When heat sealing is performed with a hot plate or the like of an automatic packaging machine, there is a possibility that a problem may occur in that the film is partially melted and a hole is formed.

The copolymer (B ₂ ), which is the second component, plays an important role in enhancing the flexibility of the film and obtaining a tight packaging finish. It is important to mix in a specific range so as not to cause the problem of melting and puncturing during sealing. That is, although it depends on the components of the crystalline polypropylene (B ₁ ), it is preferably 30% by weight to 90% by weight, more preferably 40% by weight to 7% by weight.
0% by weight or less. If the amount of the copolymer (B ₂ ) is less than 30% by weight, the flexibility of the film may be insufficient, and the effect of improving the deformation recovery property may not be sufficiently obtained. Easy to happen,
Since the heat resistance of the film is insufficient, the temperature range in which heat sealing can be performed is narrowed, and there is a possibility that a problem occurs in that the film is melted during heat sealing to form a hole.

Further, in order to adjust the flexibility and deformation recovery of the film, the third component is a copolymer of propylene or butene-1 and ethylene, wherein the content of propylene or butene-1 is 10% by weight. % Or less and less than 50% by weight of the copolymer (B ₃ ) is preferably added in a range of 30% by weight or less. The melt flow rate of the composition of the central layer (layer B) is preferably 0.1 to 10 g / 1.
0 minutes, more preferably 1.0 to 3.0 g / 10 minutes. If the melt flow rate is less than 0.1 g / 10 minutes, there is a possibility that there is a problem in extrudability, and
If the amount exceeds the above range, it is difficult to obtain a tight package, the strength characteristics may be reduced, and the molding stability may not be obtained.

The layer on the center side (layer B) in the present invention is composed of the above-mentioned resin composition, and further has an appropriate sliding property, self-adhesive property, antistatic property and anti-static property against these resin components. The same additives as in the above-mentioned surface layer (A layer) can be blended to obtain haze.

In the present invention, an ethylene-based copolymer (layer A) is provided on the surface layers on both sides of the film, and crystalline polypropylene (B ₁ ) and the copolymer are formed on the center side of the layer (layer A). (B ₂ )
The purpose of providing the layer is that a single film made of an ethylene-based copolymer cannot provide a heat-sealability, strength, and the like that are sufficiently satisfactory. Conversely, crystalline polypropylene (B ₁ ) and a copolymer This is because the flexibility, transparency, gloss, transparency, self-adhesiveness, deformation recovery property, and the like of the film cannot be sufficiently obtained with a single film composed of the composition with (B ₂ ). These problems are caused by providing an ethylene-based copolymer (layer A) on the surface layers on both sides of the film,
This problem can be solved for the first time by laminating a layer (B layer) composed of a composition of crystalline polypropylene (B ₁ ) and a copolymer (B ₂ ) on the layer closer to the center than the layer).

The stretch film for food packaging according to the present invention is provided with an ethylene copolymer (A layer) on the surface layers on both sides of the film, and a layer on the center side of the (A layer) is made of crystalline polypropylene (B). ₁ ) a laminated film having at least a three-layer structure provided with a (B layer) composed of a composition of a copolymer (B ₂ ), and the same composition is used for both sides (A layer). Alternatively, a composition belonging to the above-described composition but having a different component composition may be used. Such a laminated film can be produced by a method conventionally used using each of the above-described compositions, specifically, by an inflation method, a T-die method, an extrusion lamination method, or the like. Among them, an inflation method that has a good balance of physical properties in the vertical and horizontal directions is preferable.

The thickness of the stretch film for food packaging of the present invention is usually 8 to 30 μm, preferably 10 to 20 μm. The thickness of the film is 8 μm
If it is less than 30 μm, the handleability of the film will be significantly reduced due to a decrease in the strength and stiffness of the film, and if it exceeds 30 μm, the stress at the time of stretching the film will increase, which may cause a problem of deforming the tray and the packaged object. is there.

Further, the thickness of the center layer (layer B) of the stretch film for food packaging of the present invention is preferably 20% or more and 85% or less of the total thickness of the film.
Those having a thickness of 0 to 25.0 μm, preferably 2.0 to 17.0 μm are suitable. Here, if the thickness of the layer on the center side (layer B) is less than 20% of the total thickness of the film, the effect of improving the heat sealing property and the cutting property cannot be expected, and if it exceeds 85%, uniform elongation properties may be impaired. is there.

[0028]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. (Example 1) As a resin for the surface layer (A layer), ethylene-
A vinyl acetate copolymer was used. Melt flow rate (hereinafter abbreviated as MFR) of this copolymer (JIS-K721)
0,190 ° C., load = 2.16 kg, hereinafter MFR was 2.0 g / 10 min except for temperature), and the vinyl acetate unit content was 16% by weight. A composition comprising 98.0% by weight of the ethylene copolymer and 2.0% by weight of diglycerin monooleate was used as a resin for the surface layer (A layer). As a resin for the layer (layer B) closer to the center than the surface layer (layer A), a propylene-ethylene random copolymer (ethylene content: 7% by weight, MFR at 230 ° C.)
1.0 g / 10 min): 40% by weight, propylene-ethylene random copolymer (ethylene content 18% by weight, 23
MFR at 0 ° C .: 2.5 g / 10 min): A composition comprising 99% by weight of 60% by weight and a composition comprising 1.0% by weight of diglycerin monooleate were used. The MFR of the mixed composition at 230 ° C. was 1.5 g / 10 minutes.

Each of these resins has a diameter of 50 mm and an L / D of 26.
Are molded at a resin temperature of 190 ° C. and a blow-up ratio of 5.0 using an inflation molding machine comprising two extruders and a 100 mm annular three-layer die. Each layer has a thickness of 5 μm / 5.
A film having a thickness of 15 μm was obtained. Using this film, meat, fish, prepared foods, fruits, and the like were placed on an expanded polystyrene tray and packed by an automatic stretch packaging machine. The properties and measurement results of the film are shown in Tables 1 and 2 below.

Example 2 The same ethylene-vinyl acetate copolymer as in Example 1 was used as the resin for the surface layer (layer A).
Using a composition comprising 0% by weight and 2.0% by weight of diglycerin monooleate, as a resin for a layer (B layer) closer to the center than the surface layer (A layer), a propylene-ethylene random copolymer (containing ethylene) Amount: 4% by weight, MFR at 230 ° C .: 1.0 g / 10 min): 40% by weight, propylene
Ethylene random copolymer (ethylene content 15% by weight): 45% by weight, ethylene-propylene copolymer (propylene content 27% by weight, density 0.880 g / c)
m ³ , 1.9 g of MFR at 190 ° C./10 min): 1
A composition consisting of 99% by weight of a composition consisting of 5% by weight and 1.0% by weight of diglycerin monooleate was used. The MFR of the mixed composition at 230 ° C. was 2.0 g / 10 minutes.

Example 1 was repeated except that these compositions were used.
And the thickness of each layer is 5 μm / 5 μm / 5
μm, and a film having a total thickness of 15 μm was obtained. Using this film, meat,
Fish, side dishes, fruits, etc. were placed and packed by a stretch automatic packaging machine. The properties and measurement results of the film are shown in Table 1 below.
And Table 2.

[0032]

[0033]

Example 3 The same resin as in Example 1 was used for both the surface layer (layer A) and the layer on the center side (layer B), and further the layer on the center side (layer B).
In the layer, a portion of the film that did not become a product was collected, pulverized, and continuously charged. The recovery rate of this film scrap was 8% by weight, and the thickness of each layer was 4 μm / 6 μm.
/ 4 μm, and a film having a total thickness of 14 μm was obtained.
Using this film, a foam polystyrene tray
Meat, fish, side dishes, fruits, etc. were placed and packed by a stretch automatic packaging machine. The properties and measurement results of the film are shown in Tables 1 and 2 below.

[0035]

[Table 1]

[0036]

[Table 2]

In Tables 1 and 2, measurement and evaluation of physical properties of each item were carried out by the following methods. 1) MFR; JIS K7210 2) Density; JIS K6760 3) Haze (transparency); JIS K6714 4) Gloss (glossy); JIS K7105 5) Clarity (transparency); Slit using Clarity Meter manufactured by Murakami Color Research Laboratory Measured at a width of 1 mm 6) Breaking strength; JIS Z1702 7) Elongation; JIS Z1702 8) Deformation recovery; A specimen of 15 mm in width and 100 mm in length is extended to 200 mm, immediately released, and after 30 seconds, the length of the specimen is reduced. It was measured and indicated by the length to which the specimen returned. 9) Elongation property: It was examined whether necking occurred when the film was stretched. 10) Self-adhesiveness: Two pieces of a sample having a length and width of 100 mm were overlapped, the ends of each film were fixed to upper and lower plates with a tape, and peeled up and down to measure. 11) Anti-fog property; water 10 at 20 ° C in a 300 ml beaker
When 0 ml was put, covered with a film and stored in a refrigerator at 1 ° C., the degree of cloudiness of the film was visually evaluated on a 5-point scale.
(The best was set to 5.) 12) Heat sealing property: The heater temperature of the hot plate of the automatic wrapping machine was set at 50 to 160 ° C., and the stretch-wrapped tray was allowed to rest on the hot plate for several seconds. Evaluation was made based on the sealing strength and the presence or absence of perforations, and the temperature was shown in a temperature range in which good sealing was possible. 13) Suitability for automatic packaging machine; Judgment was made as to whether stretch packaging was possible without problems such as generation of wrinkles, cracking and distortion of trays, unwinding property of film, and cutting property. 14) Cutting performance: Sensory evaluation of cutting performance by hand in the lateral direction,
Those that were cut straight in the horizontal direction were rated as 5, and those that could not be cut or those that were bent and cut were evaluated on a 5-point scale according to the degree.

Comparative Example 1 The propylene-ethylene random copolymer used in Example 1 (ethylene unit content 7% by weight, MFR 1.0 g / 10% at 230 ° C.) was used as the resin for the center layer (layer B). Min): A film was formed in the same manner as in Example 1 except that a composition consisting of 99% by weight and 1.0% by weight of diglycerin monooleate was used, and the thickness of each layer was 5 μm / 5 μm / 5 μm; A film having a thickness of 15 μm was obtained. Packaging was performed using this film. The properties and measurement results of the film are shown in Tables 3 and 4 below.

Comparative Example 2 The propylene-ethylene random copolymer used in Example 1 (ethylene unit content: 18% by weight, 230 ° C.) was used as the resin for the center-side layer (layer B).
MFR of 2.5 g / 10 min): 99% by weight; a film was formed in the same manner as in Example 1 except that a composition consisting of diglycerin monooleate 1.0% by weight was used, and the thickness of each layer was 5 μm. / 5 μm / 5 μm; a film having a total thickness of 15 μm was obtained. Packaging was performed using this film.
The properties and measurement results of the film are shown in Tables 3 and 4 below.

Comparative Example 3 As a resin for the layer on the center side (layer B), a propylene-ethylene random copolymer (ethylene content 4% by weight, MFR 1.0 at 230 ° C.)
g / 10 min): 70% by weight; propylene-ethylene random copolymer (ethylene unit content 18% by weight, 230
MFR at 2.5 ° C./10 min): 99% by weight of a composition consisting of 30% by weight, diglycerin monooleate
A film was formed in the same manner as in Example 1 except that a composition consisting of 0% by weight was used, and the thickness of each layer was 5 μm / 5 μm / 5 μm.
m: A film having a total thickness of 15 μm was obtained. Packaging was performed using this film. The properties and measurement results of the film are shown in Tables 3 and 4 below.

Comparative Example 4 As a resin for the center layer (layer B), a propylene-ethylene random copolymer (ethylene unit content: 4% by weight, MFR 1.0 at 230 ° C.)
g / 10 min): 30% by weight; ethylene-propylene copolymer (propylene content: 27% by weight, density: 0.880 g)
/ Cm ³ , MFR at 190 ° C 2.9 g / 10
Min): A film was formed in the same manner as in Example 1 except that a composition composed of 70% by weight of 99% by weight and a composition composed of 1.0% by weight of diglycerin monooleate were used.
5 μm / 5 μm / 5 μm; a film having a total thickness of 15 μm was obtained. Packaging was performed using this film. The properties and measurement results of the film are shown in Tables 3 and 4 below.

[0042]

[Table 3]

[0043]

[Table 4]

In Tables 3 and 4, physical properties of each item were measured and evaluated in the same manner as in the examples.

[0045]

As described above, the stretch film for food packaging of the present invention is excellent in transparency, gloss and transparency.
It has uniform elongation characteristics when the film is stretched,
It has excellent heat sealing properties in an automatic packaging machine, has sufficient elongation and deformation recovery properties, is suitable for packaging machines, and has excellent workability. In addition, air permeability, anti-fog property, water vapor permeability required for stretch films for food packaging,
Physical properties such as self-adhesiveness are also good. Furthermore, there is no problem of disposal property after use like a conventional plasticized polyvinyl chloride stretch film, and there is no problem in food hygiene. Therefore, the stretch film for food packaging of the present invention is expected to be widely used as a film for stretch packaging various foods such as fruits and vegetables, fresh fish, fresh meat, and prepared foods.

Continued on the front page. (72) Inventor Toyo Shinoda, Oita-shi, Oita Prefecture, Nakanoshima 2 Showa Denko Co., Ltd. Inside Oita Research Laboratories (72) Inventor Tasuke Kinoshita, Oita-shi Oita City, Oita-shi Nakanoshima 2 Showa Denko Co., Ltd. Oita Research Institute (56) References JP-A-61-44635 (JP, A) JP-A-6-39973 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00 -35/00 B65D 65/00-65/46

Claims (6)

(57) [Claims] 1. A laminated film having at least a three-layer structure, wherein a surface layer (A layer) on both sides of the film has an ethylene-acetic acid content of 5 to 25% by weight of a monomer other than ethylene. vinyl copolymer, et styrene - acrylic acid copolymer, ethylene - methacrylic acid copolymer, comprising at least one ethylene copolymer selected from among a ionomer resin, the surface layer (a layer) The more central layer (layer B) is melt
A crystalline polypropylene (B ₁ ) having a flow rate of 0.1 to 30 g / 10 min , ethylene and carbon number of 4 to
A copolymer of at least one α-olefin selected from 12 α-olefins and propylene, wherein α
- copolymer content is 10 wt% to 30 wt% of the olefin Ri Do from (B ₂₎ and of the composition, of the center-side
Crystalline polypropylene (B) in the composition forming the layer (B layer)
Food packaging stretch film content, characterized in der Rukoto 10 wt% to 50 wt% of _one). 2. The crystalline polypropylene (B ₁ ) of the central layer (layer B) comprises ethylene and at least one α-olefin selected from α-olefins having 4 to 12 carbon atoms and propylene. a copolymer, for food packaging stretch film according to claim 1, wherein the content of α- olefin and wherein der Rukoto less than 10 wt%. 3. The layer on the center side (layer B) comprises propylene or
Is a copolymer of butene-1 and ethylene,
Len or butene-1 content is 10% by weight or more and 50 weights
The stretch film for food packaging according to claim 1 or 2 , further comprising a copolymer (B ₃ ) in an amount of less than% . 4. A laminated film having at least a three-layer structure.
Wherein the surface layers (layer A) on both sides of the film are
Ethylene-acetic acid having a monomer content of 5 to 25% by weight
Vinyl copolymer, ethylene-ethyl acrylate copolymer
Body, ethylene-methyl acrylate copolymer, ethylene-
Acrylic acid copolymer, ethylene-methacrylic acid copolymer
Body, ethylene-methyl methacrylate copolymer, ethylene
-Ethyl methacrylate copolymer, ionomer resin
At least one ethylene copolymer selected from
Made, the surface layer a layer of (A layer) from the center side (B layer), a crystalline polypropylene (B _1), ethylene and carbon atoms 4
A copolymer of at least one α-olefin and propylene selected from α-olefins of from 12 to 12,
A copolymer (B ₂ ) having an α-olefin content of 10% by weight or more and 30% by weight or less, and a copolymer of propylene or butene-1 and ethylene, wherein the propylene or butene-1 content is , stretch film for food packaging you <br/> characterized in that it is a composition of the copolymer is less than 10 wt% to 50 wt% (B _3). 5. The content of the copolymer (B ₂ ) in the composition forming the central layer (layer B) is at least 30% by weight and at least 90% by weight.
Hereinafter, content of the copolymer (B ₃₎ is, according to claim 3 Mahata claim 4 food packaging stretch film, wherein a 30% by weight or less. 6. A center of the layer food packaging melt flow rate (B layer) of the composition according to 5 any one claims 1, characterized in that a 0.1 to 10 g / 10 min For stretch film.