JP2001162737A - Multi-layer film for packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-layer film for packaging which is excellent in low temperature shrinkability, high in transparency and glossiness, good in tear strength, high in low temperature seal strength, and excellent in heat resistance, free from melt-down when heated by a microwave oven etc., and suitable for folding type pillow packaging. SOLUTION: A film 1.5% or below in haze, at least 130% in gloss, at least 25% in heat shrinkage ratio at 100 deg.C in longitudinal and cross directions, and at least 100 g/15 cm in peeling resistance in specified heat seal conditions which comprises at least five layers in which, between both surface layers of a specified ethylene resin and an intermediate layer of crystalline polypropylene or a polypropylene resin containing a resin composition comprising an amorphous polyolefin of specified composition and crystalline polypropylene as main components, at least one adhesive layer comprising a specified ethylene resin different from both surface layers exists is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film for packaging having excellent low-temperature shrinkability, high transparency and high gloss, good tear strength and low-temperature and high seal strength. The film of the present invention can be suitably used especially for folding pillow packaging.

[0002]

2. Description of the Related Art In recent years, as a material for a flexible film, a flexible vinyl chloride film containing a plasticizer has been widely used. However, soft vinyl chloride resin is excellent in transparency, low-temperature shrinkage, etc., but has poor low-temperature resistance. Occurs and causes social problems such as the problem of acid rain.

As a soft film similar to the soft vinyl chloride film, there is a film mainly composed of ethylene such as an ethylene-vinyl acetate copolymer, a low density polyethylene and an ionomer. These ethylene-based soft films, especially soft low-density polyethylene films are waterproof,
Excellent moisture proof, moderately flexible, relatively transparent, and heat sealable from a relatively low temperature, but inferior to soft vinyl chloride film in terms of transparency, haze, gloss, etc.
There are also disadvantages inferior in heat resistance and waist strength.

On the other hand, the softness of polypropylene resin, which is excellent in mechanical properties such as tensile strength, rigidity, surface hardness, impact strength and the like, and optical properties such as gloss and transparency, and is non-toxic and odorless, is also excellent in food hygiene. The conversion is carried out by lowering the melting point by randomly copolymerizing propylene and ethylene, and maintaining flexibility while maintaining sufficient mechanical and optical properties. However, it is difficult for polypropylene resin alone to have flexibility comparable to soft vinyl chloride resin. In addition, when heat-sealing such a polypropylene film, the temperature must be extremely high, and since the appropriate temperature range for heat-sealing is narrow, strict temperature control is required when heat-sealing with an automatic packaging machine, an automatic bag making machine, or the like. Will be needed.

[0005] Therefore, it is necessary to improve the low-temperature heat-sealing property by using a polypropylene film as a base material, and laminating one or both surfaces thereof by coating, laminating, or co-extruding a resin that can be heat-sealed at a lower temperature. Is being done. For example, as a laminated film having good low-temperature heat sealability, high flexibility, and excellent heat resistance, propylene and / or butene-
A layer (A) composed of a resin composition containing 20 to 100% by weight of an amorphous polyolefin having a one-component content of 50% by weight or more and 80 to 0% by weight of a crystalline polypropylene, and an ethylene-based resin ( B) and at least two layers, and at least one of both outer layers is a layer (B) (see JP-A-6-927), propylene and / or Amorphous polyolefin 20 having a butene-1 component content of 50% by weight or more
-100% by weight and crystalline polypropylene 80-0% by weight
(A) composed of a resin composition obtained by blending 0.5 to 50 parts by weight of an ethylene resin with respect to 100 parts by weight of a mixture containing Film (Japanese Patent Laid-Open No. 7-27)
No. 6584) has been proposed.

[0006]

However, these laminated films do not yet have satisfactory optical properties such as gloss and transparency and low-temperature heat sealability as packaging films. The present invention has been made in view of the above-described circumstances, and has excellent low-temperature shrinkability, high transparency, high gloss, and good tear strength and low-temperature and high seal strength, and is a multilayer film for packaging suitable for folding pillow packaging. The purpose is to provide.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have proposed a multi-layer structure in which a polyethylene film layer and a polypropylene film layer are laminated and the polyethylene film layer is an outer layer. As a result of intensive studies on the axially stretched film, a multilayer structure of at least five layers in which at least one adhesive layer made of an ethylene-based resin exists between both surface layers made of an ethylene-based resin and an intermediate layer made of a polypropylene-based resin In the biaxially stretched film, a linear low-density polyethylene having a specific density and a melt index produced using a metallocene catalyst as an ethylene resin for both surface layers, and propylene as a polypropylene resin for the intermediate layer. −
α-olefin random copolymer, or an amorphous polyolefin having a specific composition or a resin composition obtained by blending the amorphous polyolefin and crystalline polypropylene in a specific ratio, preferably at a high temperature of 100 to 130 ° C. It was found that the above-mentioned object of the present invention was achieved by stretching the film, and the present invention was completed.

That is, the gist of the present invention is that the density is 0.8
Both surface layers comprising an ethylene-based resin (A) containing 80 to 0.910 g / cm ³ and a melt index of 0.5 to 20 g / 10 minutes mainly composed of linear low-density polyethylene (a ₁ ); -Α-olefin random copolymer (b ₁ ) or 20 to 100% by weight of an amorphous polyolefin having a propylene component and / or butene-1 component content of 50% by weight or more and 80 to 0% of a crystalline polypropylene. The density between 0.910 and 0.945 g / cm ³ and the melt index between the intermediate layers composed of the polypropylene resin (B) whose main component is the resin composition (b ₂ ) containing 0.1% by weight. 1 to 10 g / 10 min 2 an adhesive layer comprising an ethylene-based resin (C) is composed of at least five layers there is at least one layer composed mainly of linear low density polyethylene (c ₁₎ A stretched film, 1.5% haze value of the film below, the gloss value 130%
The heat shrinkage in the longitudinal direction and the transverse direction at a temperature of 100 ° C. are both 25% or more, the tear strength in the longitudinal direction and the transverse direction are both 2 kg / cm or more, and the sealing pressure between the surface layers is 1 kg / cm ² G, seal temperature 9
A film having a width of 15 mm obtained by heat sealing at 0 ° C. and a sealing time of 1 second is applied at a pulling speed of 100 mm / min.
When peeled in the direction of 0 degrees, the peeling resistance is 100 g / 1.
Exists in a multilayer film for packaging that is 5 mm or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The ethylene resin (A) constituting both surface layers of the multilayer film for packaging of the present invention has a density of 0.880 to 0.91.
0 g / cm ³ , preferably 0.890-0.905 g /
cm ³ and a melt index (MI _2.16 ) at 190 ° C. and a load of 2.16 kg of 0.5 to 20 g / 10.
The main component is a linear low-density polyethylene (a ₁ ) whose content is preferably 0.5 to 10 g / 10 minutes.
When the density is less than 0.880 g / cm ³ , insufficient strength (particularly, tear strength) of the film, excessive stickiness of the surface, and the like occur. The density is 0.910 g / cm
^If it exceeds ³ , flexibility, low-temperature heat sealability, low-temperature shrinkage, transparency and the like will be poor. On the other hand, when MI _2.16 is less than 0.5 g / 10 minutes, thickness unevenness is apt to occur, and the stretchability becomes poor.
Insufficient sealing strength of the sealing portion and insufficient strength of the film occur, and the moldability also deteriorates.

Here, (a)₁) Ingredients are single size
Straight-chain ethylene having a short-chain branch that can be produced from a catalyst.
A ren-α-olefin copolymer, having the above density and
In addition to the melt index, the following properties (1) 19
Melt index at 0 ° C and 10.0kg load
(MI_10.0) And the MI_2.16And the ratio [(MI_10.0) /
(MI_2.16)] Is 1 to 20, (2) molecular weight distribution (Mw /
Mn) is 2.0 to 4.0, and (3) the Vicat softening point is 80.
To 105 ° C, (4) by differential scanning calorimeter (DSC)
If one or more melting points to be measured and one
If there is more than one melting point,
(5) the maximum melting point is in the range of 100 to 120 ° C.
In the melting curve obtained by the DSC measurement
Below 10 ° C lower than the melting point (endothermic main peak)
Heat absorption area of 50% or less of the total heat absorption area, and (6)
High melting point heat of crystal melting (H₁) And the total crystal fusion heat (H_T)
0 <H ₁/ H_TThose with ≦ 0.40 are preferred
No.

The ethylene-α-olefin copolymer as the component (a ₁ ) can be produced by copolymerizing ethylene with an α-olefin having 3 to 12 carbon atoms in the presence of a single-site catalyst. it can. 3 to 1 carbon atoms
As the α-olefin of 2, propylene, butene-
1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, nonene-1, decene-1 and the like. The repeating unit derived from the α-olefin in the ethylene-α-olefin copolymer is preferably in a range of 20 mol% or less, more preferably 0.1 to 1 mol%.
It is contained in the range of 5 mol%, more preferably in the range of 1 to 12 mol%. Further, the α-olefin may be present alone in the ethylene-α-olefin copolymer, or may be contained in two or more kinds.

As the single-site catalyst, a combination of a metallocene compound of a transition metal of Group IV or Group V of the periodic table with an organic aluminum compound and / or an ionic compound is used. As the transition metal of Group IV or Group V of the periodic table, titanium (Ti), zirconium (Zr), hafnium (Hf), and vanadium (V) are preferable. Examples of the metallocene compound include dimethylsilyl (2,4-dimethylcyclopentadienyl) (3 ′, 5′-dimethylcyclopentadienyl) zirconium dichloride and dimethylsilyl (2,4-dimethylcyclopentadienyl) ( 3 ',
At least one cyclopentadienyl such as a silicon-bridged metallocene compound such as 5'-dimethylcyclopentadienyl) hafnium dichloride; an indenyl-based bridged metallocene compound such as ethylenebisindenylzirconium dichloride; ethylenebisindenylhafnium dichloride; Any of the known metallocene compounds having, as ligands, those which are cross-linked by a group, substituted cyclopentadienyl group, hydrocarbyl silicon or the like, and those in which the cyclopentadienyl group is cross-linked by oxygen, nitrogen and phosphorus atoms it can.

The organoaluminum compound used in combination with the metallocene compound includes the following general formula (I)

[0014]

Embedded image

(Wherein, R is a hydrocarbon group having 1 to 10 carbon atoms, including those partially substituted by halogen atoms and / or RO groups (R is the same as described above. N is the degree of polymerization) And 5 or more, preferably 10 or more.), And specific examples include methylalumoxane, ethylalumoxane and isobutylethylalumoxane wherein R is a methyl group, an ethyl group and an isobutyl group, respectively. .

Further, the ionic compound used in combination with the metallocene compound, general formula, Q ⁺ · Y ^- is a compound represented by. Here, Q ⁺ is an oxidizing cation of an organic compound, an organometallic compound, or an inorganic compound, or a Bronsted acid comprising a Lewis base and a proton, and reacts with an anion of a metallocene ligand to form a metallocene cation. can do. As the anion component Y ⁻ , an organic boron compound anion,
Organic aluminum compound anions, organic gallium compound anions, organic phosphorus compound anions, organic arsenic compound anions, organic antimony compound anions, and the like.
Specific examples thereof include an ionic compound of a tetrakis (pentafluorophenyl) borate anion and a triphenylcarbonium cation or a dialkylanilinium cation.

As the (co) polymerization method of ethylene with the single-site catalyst, various well-known methods can be employed, such as fluidized-bed gas-phase polymerization or inert gas-phase polymerization in an inert gas. Examples thereof include slurry polymerization in a solvent and bulk polymerization using a monomer as a solvent.

In the present invention, the ethylene-based resin (A) constituting both surface layers is mainly composed of the component (a ₁ ) as described above.
₁ ) 0.3 to 5 parts by weight, preferably 0.5 to 2 parts by weight of an antifogging agent (d) and 100 parts by weight of a base resin (A ₁ ) mainly composed of a component, and an antioxidant ( e) is 0.01
To 0.5 parts by weight, preferably 0.02 to 0.2 parts by weight. Here, the base resin (A ₁ ) mainly composed of the component (a ₁ ) refers to the component (a ₁ )
20 to 50 parts by weight, preferably 30 to 30 parts by weight of the low-crystalline ethylene-α-olefin copolymer (a ₂ ) per 100 parts by weight.
45 parts by weight, a low density polyethylene (a ₃₎ 3 to 20
Parts by weight, preferably 1 to 5 parts by weight of 5 to 15 parts by weight optionally linear low density polyethylene (a _4), preferably is preferable which contains 2-4 parts by weight.

The component (a ₂ ) has a density of 0.8
70 to 0.905 g / cm ³ , preferably 0.880 to
The melt index (MI _2.16 ) at 0.900 g / cm ³ , 190 ° C. and 2.16 kg load is 0.1 to 10
g / 10 min, preferably 0.2 to 6 g / 10 min, and the Vicat softening point is usually 80 ° C. or lower, preferably 75 ° C. or lower, more preferably 70 ° C. or lower, still more preferably 60 ° C. or lower, and the crystallinity ( (X-ray method) having characteristics of 5 to 40%, preferably 5 to 30%.
A random copolymer with α-olefin 2 is preferably used.

The above-mentioned ethylene having 3 to 1 carbon atoms copolymerized with ethylene
Specific examples of the α-olefin of 2 include propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, nonene-1, decene-1, or a mixture thereof. Among them, an α-olefin having 3 to 5 carbon atoms, particularly butene-1 is preferred.

Examples of the component (a ₂ ) include those commercially available under the trade names such as Tuffmer A4085 and Tuffmer A1575 manufactured by Mitsui Chemicals, Inc. Further, the production method is based on a vanadium compound such as vanadyl trichloride, monoethoxy vanadyl dichloride, triethoxy vanadyl, vanadium oxydiacetylacetonate, vanadium triacetylacetonate, and an empirical formula: R ′ _m AlX
_3-m (where R 'is a hydrocarbon group such as an alkyl group, X is hydrogen, chlorine or an alkoxy group having 2 to 4 carbon atoms, and 0 <m ≦ 3). A method in which ethylene and the above-mentioned α-olefin having 3 to 12 carbon atoms are copolymerized in the presence of a solvent using a catalyst comprising an aluminum compound is preferable, but not limited thereto.

In the component (a ₂ ), the density is 0.8
If it is less than 70 g / cm ^3, the mechanical strength and heat seal strength of the film will be reduced, and the surface will be sticky to easily cause blocking. If it exceeds 0.905 g / cm ³ , the effect of improving low-temperature heat sealability will be obtained. May not be fully exhibited. The melt index (M
In the case where I _2.16 ) is less than 0.1 g / 10 minutes, the effect of improving the low-temperature heat sealability is not sufficiently exhibited, and 10 g
When the time exceeds / 10 minutes, the blocking property of the film tends to deteriorate, and the mechanical strength tends to decrease. further,
If the crystallinity is less than 5%, the surface becomes sticky,
The film is susceptible to blocking resistance and 40%
If the ratio exceeds 1, the effect of improving the low-temperature heat sealability is not sufficiently exhibited, which is not desirable.

[0023] In the ethylene-based resin (A) constituting the both surface layers of the present invention, the (a ₂₎ the amount of low crystalline ethylene -α- olefin copolymer which is a component wherein (a ₁₎ component 100 When the amount is less than 20 parts by weight per part by weight, the low-temperature heat sealability is not sufficiently imparted,
This is not desirable because the transparency may be reduced. On the other hand, when the amount is more than 50 parts by weight, the mechanical strength of the surface layer as the heat seal layer is reduced, the blocking of the film becomes severe, and the slipperiness between the films or the metal becomes poor. Problems can occur and are undesirable.

The low-density polyethylene as the component (a ₃ ) is not particularly limited, but (1) has a density of 0.900 to 0.940 g / cm ^3, preferably 0.92 g / cm ^3.
0 to 0.930 g / cm ³ , (2) 190 ° C., 2.16
The melt index (MI _2.16 ) under a kg load is 0.5 to 50 g / 10 min, preferably 1 to 10 g / 10 min.
(3) Crystallinity (X-ray method) is 40 to 70%, and (4) Melting point (in the melting curve) measured by a differential scanning calorimeter (DSC). A high-pressure low-density polyethylene having an endothermic main peak) of 100 to 120 ° C. is preferred. This high-pressure low-density polyethylene is obtained by polymerizing ethylene alone or ethylene and other copolymerized components at a polymerization pressure of 1000 to 4000 kg / c.
m ² , at a temperature of 230 to 360 ° C., in the presence of a radical polymerization initiator and a chain transfer agent, in a tubular reactor or a tank reactor, which can be produced by radical polymerization, but is not limited thereto. Not something.

As the other copolymerization component, α-C 3-8 α such as propylene, butene-1, isobutylene, hexene-1, 4-methylpentene-1 and octene-1 can be used.
-Olefin, vinyl acetate, ethyl acrylate, methyl acrylate, methyl methacrylate, butyl acrylate and the like. The content of these other copolymer components is 5 to 30 mol% in the case of α-olefin,
In the case of vinyl acetate, it is preferably at most 30 mol%.

Specific examples of the component (a ₃ ) include ethylene homopolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl acrylate copolymer, and ethylene / methacrylic acid. Examples include a methyl copolymer, an ethylene / butyl acrylate copolymer, an ethylene / propylene copolymer, and an ethylene / butene-1 copolymer. Among these, an ethylene homopolymer is preferable.

In the present invention, the component (a ₃ ) is used as a master batch with the antifogging agent (d) so that the antifogging agent (d) is uniformly mixed and dispersed in the ethylene resin (A). To use. Therefore, when the amount of the component (a ₃ ) is less than 3 parts by weight based on 100 parts by weight of the component (a ₁ ), the anti-fogging effect may not be sufficiently exhibited. On the other hand, if the amount of the component (a ₃ ) is more than 20 parts by weight based on 100 parts by weight of the component (a ₁ ), the mechanical strength, particularly the impact strength and the tear strength of the film tends to decrease.

Further, both layers of the multilayer film for packaging of the present invention are provided.
The above-mentioned (a) optionally used for the surface layer_Four) Components
In the presence of a single-site catalyst, ethylene and propylene
, Butene-1, pentene-1, hexene-1, 4-meth
Chilpentene-1, octene-1, nonene-1, decene
One kind of α-olefin having 3 to 12 carbon atoms such as -1 or
By copolymerizing two or more kinds with the above-mentioned known method,
Linear ethylene-α- having short-chain branches that can be produced
An olefin copolymer, wherein (1) the carbon in the copolymer is
The α-olefin content of a prime number of 3 to 12 is preferably 20
Mol% or less, more preferably 0.1 to 15 mol%,
Preferably 1 to 12 mol%, and (2) a density of 0.890.
~ 0.925g / cm^Three , Preferably 0.910-0.
920 g / cm^Three , (3) 190 ° C, 2.16 kg load
Melt index (MI_2.16) Is 0.5-2
0 g / 10 min, preferably 0.5 to 10 g / 10 min,
(4) Melt-in at 190 ° C and 10.0 kg load
Decks (MI_10.0) And the MI_2.16And the ratio [(MI
_10.0) / (MI_2.16)] Is 1 to 20, (5) molecular weight distribution
(Mw / Mn) 2.0-4.0, (6) Vicat softening
(7) Differential scanning calorimeter (DS)
C) there is more than one melting point
The maximum melting point is in the range of 100 to 120 ° C.
(8) melting obtained by the DSC measurement
10 ° C lower than melting point (endothermic main peak) in the curve
Heat absorption area below 50% of the total heat absorption area
And (9) the maximum heat of crystal fusion (H₁) And whole crystal melting
Calorie (H_T) And 0 <H ₁/ H_T≤0.40
Are preferred. The single-site catalyst
As described above (a₁) Use the same components as
Can be used.

Ethylene resin (A) constituting both surface layers
In the above, the component (a ₄ ) is not an essential component, but has a role as a density regulator for the entire ethylene resin (A), and the antioxidant (e) is uniformly contained in the ethylene resin (A). It is used as a master batch with the antioxidant (e) so as to be mixed and dispersed. Therefore,
If the compounding amount is less than 1 part by weight per 100 parts by weight of the component (a ₁ ), the effect of suppressing resin burning and gel generation during molding may not be sufficiently exerted,
₁ ) If the amount is more than 5 parts by weight per 100 parts by weight of the components, the film may develop color or smell, and in either case, it is not desirable.

On the other hand, the antifogging agent (d) added to the ethylene resin (A) constituting the both surface layers is a mixture of a glycerin condensed polymer fatty acid ester, a glycerin monofatty acid ester and a polyoxyethylene alkyl ether. is there. The glycerin condensed polymer fatty acid ester as one component of the component (d) is a compound obtained by esterifying at least one of the hydroxyl groups of the glycerin condensed polymer with a fatty acid such as a higher fatty acid having 8 to 22 carbon atoms. . Here, the glycerin condensation polymer is a condensation polymer having a degree of polymerization of usually 2 to 10, preferably 2 to 6. Among the hydroxyl groups of the glycerin condensation polymer, the number of esterified hydroxyl groups is 1
Or more, preferably one or more and 7 of the number of hydroxyl groups.
0% or more. The higher fatty acid may be saturated or unsaturated as long as it is a fatty acid having 8 to 22 carbon atoms.
It is preferably a fatty acid of 0-18.

Examples of the glycerin condensed polymer fatty acid ester include diglycerin monolaurate, diglycerin monopalmitate, diglycerin monooleate, diglycerin dilaurate, and triglycerin monooleate. Particularly, diglycerin monolaurate and diglycerin monooleate are preferred. The compounding amount of the glycerin-condensed polymer fatty acid ester is based on the base resin (A ₁ ) 1 containing the above component (a ₁ ) as a main component.
0.1 to 3 parts by weight, preferably 0.1 to 3 parts by weight, per 100 parts by weight.
It is 2 to 2 parts by weight. If the amount is less than 0.1 parts by weight, the anti-fogging effect that the film does not fog even if vapor adheres to the film is not sufficient. If the amount exceeds 3 parts by weight, the balance between the components of the anti-fogging agent is lost, which is not preferable.

Examples of the glycerin monofatty acid ester, which is another component of the component (d), include glycerin monooleate, glycerin monolaurate, glycerin monopalmitate, glycerin monostearate and the like. Particularly, glycerin monooleate and glycerin monolaurate are preferred. The amount of the glycerin monofatty acid ester is 0.05 to 3 parts by weight, preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the base resin (A ₁ ) mainly composed of the component (a ₁ ). . If the amount is less than 0.05 part by weight, the effect of imparting anti-fogging property to the film is not sufficient, and if it exceeds 3 parts by weight, stickiness and remarkable slippage occur in the obtained film,
Workability may be reduced.

The polyoxyethylene alkyl ether which is another component of the component (d) is a compound in which a terminal hydroxyl group of a condensation polymer of ethylene glycol is etherified with a higher alcohol having 8 to 22 carbon atoms. . Here, the condensation polymer of ethylene glycol is a condensation polymer having a degree of polymerization of usually 2 to 10, preferably 2 to 6. The higher alcohol may be saturated or unsaturated as long as it is an alcohol having 8 to 22 carbon atoms, and is usually preferably an alcohol having 10 to 18 carbon atoms. Particularly, lauryl alcohol is preferred. The compounding amount of the polyoxyethylene alkyl ether is 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the base resin (A ₁ ) mainly composed of the component (a ₁ ). It is. If the amount is less than 0.05 parts by weight, a sufficient antifogging effect cannot be obtained. If the amount exceeds 2 parts by weight, the balance between the components of the anti-fogging agent is lost, which is not preferable.

When the amount of the antifogging agent (d) is less than 0.3 parts by weight based on 100 parts by weight of the base resin (A ₁ ) mainly composed of the component (a ₁ ), the antifogging property is reduced. May be inferior. On the other hand, when the amount is more than 5 parts by weight, the film surface may be sticky, the blocking resistance may be poor, and the film may have a low seal strength. Further, the antifogging agent may be dissolved in the cooling water during film formation, and the problem of cooling water contamination such as generation of bubbles and deterioration of water quality may occur.

Further, it is preferable to add an antioxidant (e) to the ethylene resin (A) constituting both surface layers of the multilayer packaging film of the present invention. Preferable examples of the antioxidant (e) include phenol-based and phosphorus-based ones, and a combination of these is particularly preferred. Examples of phenolic antioxidants include, for example, 6-t
-Butyl-3-methylphenyl derivative, 2,6-di-
t-butyl-p-cresol, 2,2′-methylenebis- (4-methyl-6-t-butylphenol), 2,
2'-methylenebis- (4-ethyl-6-t-butylphenol), 4,4'-butylidenebis (6-t-butyl-m-cresol), 4,4'-thiobis (6-t-
Butyl-m-cresol), 4,4-dihydroxydiphenylcyclohexane, alkylated bisphenol, styrenated phenol, 2,6-di-t-butyl-4-methylphenol, n-octadecyl-3- (3 ′, 5 ′)
-Di-t-butyl-4'-hydroxyphenyl) propionate, 2,2'-methylenebis- (3-methyl-6
-T-butylphenol), 4,4'-thiobis (3-
Methyl-6-t-butylphenol), 4,4′-butylidenebis (3-methyl-6-t-butylphenol), stearyl-β (3,5-di-4-butyl-4-)
(Hydroxyphenyl) propionate, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6
-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3-
(3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane, tris (3,5-di-
t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate,
1,3,5-tris (2-hydroxyethyl) -s-triazine-2,4,6 (1H, 3H, 5H) -trione and 3,5-di-t-butyl-4-hydroxy-hydrocinnamic Triester with acid, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thio-diethylenebis [3- (3 5-di-t-butyl-4-hydroxyphenyl) propionate], N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxy-3,5-di-tert-butylanilino) -1,
3,5-triazine], tris [β- (3,5-di-t
-Butyl-4-hydroxyphenylpropionyl-oxyethyl] isocyanurate. These phenolic antioxidants are compounds having a molecular weight of 500 or more, preferably 690 or more.

Examples of the phosphorus antioxidant include, for example,
Distearylpentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) -4,
4'-biphenylenediphosphite, trisnonylphenyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, di (2,4-di-t-butylphenyl) -pentaerythritol diphosphite, Bis- (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, diphenylisodecyl phosphite, tris (nonylphenyl) phosphite sodium phosphite, triphenyl phosphite and the like. .

[0037] The (e) the amount of added components linear low density polyethylene (a ₁₎ a base resin mainly composed of (A ₁₎
When the amount is less than 0.01 part by weight based on 100 parts by weight, the antioxidant effect of the ethylene-based resin (A) is reduced,
Resin scorch occurs during molding, and gel tends to increase in the film. Also, if it exceeds 0.5 parts by weight,
Not only does the resulting film develop color or smell, but also the antioxidant bleeds out over time, possibly damaging the film appearance.

Next, the polypropylene resin (B) constituting the intermediate layer of the multilayer film for packaging of the present invention will be described. This polypropylene resin (B) is propylene-
α-olefin random copolymer (b ₁ ) or a resin composition comprising 20 to 100% by weight of a specific amorphous polyolefin and 80 to 0% by weight of crystalline polypropylene (b)
₂ ) and the low crystalline ethylene-α-olefin copolymer (a ₂ ). Specifically, based on 100 parts by weight of the component (b ₁ ) or the component (b ₂ ),
Wherein (a ₂₎ 5 to 40 parts by weight of component, preferably 10 to
30 parts by weight, 0.3 to 5 parts by weight of the antifogging agent (d),
Preferably, 0.5 to 2 parts by weight is contained. The component (a ₂ ) is also used as a base resin of a masterbatch with the antifogging agent (d) so that the antifogging agent (d) is uniformly mixed and dispersed in the polypropylene resin (B). It is. Therefore, when the content of the component (a ₂ ) is less than 5 parts by weight based on 100 parts by weight of the component (b ₁ ) or the component (b ₂ ), flexibility, impact strength, transparency, and molding of the film are reduced. And the interlayer adhesion between the ethylene-based resin (A) forming the both surface layers and the ethylene-based resin (C) forming the adhesive layer, etc., and the effect of improving tear strength and anti-fogging property is sufficiently improved. It may not be exhibited, which is not desirable. Conversely, if the content of the component (a ₂ ) exceeds 40 parts by weight based on 100 parts by weight of the component (b ₁ ) or the component (b ₂ ), the heat resistance and stretchability of the film may be reduced. Is not desirable. On the other hand, if the amount of the component (d) is less than 0.3 parts by weight based on 100 parts by weight of the component (b ₁ ) or the component (b ₂ ), the film may have poor antifogging properties. If the amount exceeds 5 parts by weight, the film surface may be sticky or the blocking resistance may be poor.

In the present invention, the component (b ₁ ) is a crystalline propylene-α-olefin random copolymer. Although its characteristics are not particularly limited,
(1) a density of 0.880 to 0.910 g / cm ³ ,
(2) 230 ° C., 2.1 according to ASTM D1238
The melt flow rate measured under a load of 6 kg is 0.
1 to 30 g / 10 min, preferably 0.3 to 20 g / 10
(3) The α-olefin content as a comonomer component is 30% by weight or less, preferably 1 to 25% by weight, more preferably 1 to 15% by weight, and (4) the Vicat softening point is 130 ° C or less, preferably 125 ° C or less, and (5)
The amount of the soluble part in cold xylene is not more than 15% by weight, preferably
It is preferably at most 10% by weight, more preferably at most 10% by weight. If the Vicat softening point exceeds 130 ° C, the resulting film may have poor low-temperature heat sealability. The amount of the soluble part in cold xylene was determined by dissolving 5 g of the polymer sample in 500 ml of xylene, then gradually cooling to room temperature, and further standing in a bath at 20 ° C. for 4 hours. The filtrate obtained by filtration was concentrated and dried. It is determined by weighing the solid after drying, but if this value exceeds 15% by weight, the obtained film may have poor blocking resistance, and the amount of solvent extraction increases. Not preferred.

As the α-olefin as the comonomer component, excluding propylene, an α-olefin having 2 or more carbon atoms, preferably 2 to 8 carbon atoms, for example, ethylene, butene-1, pentene-1, 4-methylpentene 1, hexene-1, heptene-1 and octene-1 alone or in combination of two or more. Among these α-olefins, ethylene and butene-1 are preferred.

The production of the component (b ₁ ) is not particularly limited, and can be produced by a known method. For example,
It is a known α-olefin stereoregular polymerization catalyst,
A so-called Ziegler-Natta catalyst, that is, a transition metal compound of Groups IV to VIII of the periodic table (for example, titanium,
Halogen compounds such as vanadium) and Periodic Tables I to I
An organic compound of a Group II typical metal (for example, an organic aluminum compound such as triethylaluminum, diethylaluminum chloride, etc.) and preferably an electron-donating compound as a third component (for example, esters, thioesters, amines, ketones, Nitriles, phosphines,
Ethers, thioethers, acid anhydrides, acid amides,
Propylene and the above-mentioned propylene by a solution polymerization method, a slurry polymerization method, a gas phase polymerization method, or the like, using a known catalyst system such as a catalyst system comprising an organic silicon compound or the like, in the presence of hydrogen or in the absence of hydrogen. Can be produced by polymerizing an α-olefin having 2 or more carbon atoms excluding the above.

In the present invention, the specific amorphous polyolefin which is one component of the component (b ₂ ) is a non-crystalline polyolefin having a propylene component and / or butene-1 component content of 50% by weight or more. Any crystalline olefin polymer may be used. For example, amorphous polypropylene or polybutene-1 or a copolymer of propylene or butene-1 and an α-olefin having 2 to 8 carbon atoms other than these can be used. As described above, as the α-olefin having 2 to 8 carbon atoms excluding propylene and butene-1, ethylene, pentene-1, hexene-1, heptene-1, 4-methylpentene-1, hexene-1, Heptene-1 and octene-1 and the like. These α-olefins can be used alone or in appropriate combination of two or more kinds. When the content of the propylene component and / or butene-1 component in the amorphous polyolefin is less than 50% by weight, it is difficult to form a film layer, and the mechanical strength and heat resistance are reduced. Not desirable.

It is preferable that the amorphous polyolefin has a boiling n-heptane insoluble content, that is, a content of Soxhlet extracted insoluble content with boiling n-heptane of 60% by weight or less, preferably 50% by weight or less. When the boiling n-heptane-insoluble content is more than 60% by weight, the ratio of the amorphous portion decreases, and the flexibility and uniform stretchability of the film decrease. The boiling n-heptane insoluble content was determined by using a double-tube Soxhlet extractor, and measuring 50 to 200 times the amount of n with respect to the weight of the amorphous polyolefin to be measured.
-Several hours (usually 5 to 24 hours) using heptane
It is calculated from the weight ratio of the measurement sample before and after boiling and refluxing and extracting with boiling n-heptane. The amorphous polyolefin preferably has a number average molecular weight (M
n) is preferably from 1,000 to 200,000, more preferably from 1,500 to 100,000. If the number average molecular weight (Mn) exceeds 200,000, film formation is difficult, and if it is less than 1,000, the mechanical strength will decrease.

The specific amorphous polyolefin of the present invention is a polyolefin that exhibits substantially the same behavior as amorphous, and has a crystallinity of 30% or less, usually 0.1 to 20.
% Low-crystalline polyolefin, with a density of 0.88
5 g / cm ³ or less, usually 0.855 to 0.885 g /
cm ³ . In addition, the crystallinity referred to here is JIS
Based on the density measured by the density gradient tube method of K7112, the density of 100% crystal of polypropylene was 0.936 g / c.
m ³ , a value calculated by setting the density of the amorphous to 0.855 g / cm ³ . The sample used for the density measurement is prepared by sandwiching an amorphous polyolefin pellet between metal plates coated with Teflon, heating and compressing the sheet at 190 ° C., forming a sheet, and then allowing the sheet to cool at 23 ° C. is there.

Further, the specific amorphous polyolefin of the present invention preferably has a heat of crystal fusion of a predetermined value or less. That is, when the amorphous polyolefin is a propylene / butene-1 copolymer, the heat of crystal fusion is 10 Jo.
It is preferably less than ule / g, and when the amorphous polyolefin is a propylene / ethylene copolymer, the heat of crystal fusion is preferably less than 20 Joule / g. The heat of crystal fusion is measured by a differential scanning calorimeter (DS
This is a value calculated using a straight line obtained by directly extrapolating the specific heat curve of the polymer in the completely molten state according to C) to the low temperature side as a baseline. The measurement was performed using a DSC-50 manufactured by Shimadzu Corporation as a DSC, and the sample amount was about 10 m.
g. The measurement is performed using a nitrogen atmosphere as the measurement atmosphere and using indium as a calorific value standard. As a heating program, the sample was heated at a rate of 50 ° C./min.
The temperature was raised to 0 ° C., left at this temperature for 5 minutes, cooled to −42 ° C. at a rate of 100 ° C./min, left at −42 ° C. for 5 minutes, and then −40 ° C. at a rate of 20 ° C./min. What is necessary is just to perform measurement from ℃ to 200 ℃.

Specific examples of the amorphous polyolefin include the propylene component and / or butene-1 described above.
Propylene homopolymer, butene-1 homopolymer, propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene /
Ternary copolymer of butene-1 · ethylene, terpolymer of propylene / hexene-1 / octene-1, terpolymer of propylene / hexene-1,4-methylpentene-1, butene-1 Ethylene copolymer, terpolymer of butene-1, hexene-1, octene-1, butene-1.
Hexene-1 / 4-methylpentene-1 terpolymer and the like. Amorphous polyolefin is propylene
In the case of an ethylene copolymer, the ethylene component content is 0.0
1 to 30% by weight, preferably 1 to 20% by weight is desirable. When the content of the ethylene component is more than 30% by weight, the mechanical strength of the obtained film decreases. In the present invention, the amorphous polyolefin can be used alone or in combination of two or more.

As the amorphous polypropylene used in the present invention, atactic polypropylene produced as a by-product during the production of crystalline polypropylene may be used, or it may be used as it is produced from raw materials. Also used in the present invention,
As a copolymer of propylene and / or butene-1 and an α-olefin having 2 to 8 carbon atoms excluding these, a target produced from a raw material so as to contain a predetermined propylene component and / or butene-1 component Can be used. When the objective production is carried out, a raw material monomer comprising propylene and / or butene-1 and, if necessary, an α-olefin as a copolymerization component is mixed with a known polymerization catalyst, for example, a titanium-supported catalyst supported on magnesium chloride and triethylaluminum. Can be produced by (co) polymerization in the presence or absence of hydrogen using a catalyst system consisting of In the present invention, from the viewpoint of supply stability and quality stability, it is preferable to use an amorphous polyolefin that has been produced and has predetermined characteristics.
Moreover, if there is a commercial product having the same composition and characteristics as the present invention, a commercial product can be appropriately selected and used.

On the other hand, the amorphous propylene / butene-1 copolymer used in the present invention and the amorphous propylene / butene-1
Examples of the 1. ethylene terpolymer include a copolymer mainly composed of propylene and a copolymer mainly composed of butene-1. In these copolymers, the main component is 50% by weight or more, and the remaining components are less than 50% by weight, preferably 1 to 45% by weight.
More preferably, the content is 5 to 44% by weight. Each of these propylene / butene-1 copolymers can be suitably used as the amorphous polyolefin of the present invention because of its high tensile elongation, rebound resilience and cohesion. More specifically, for example, Hunts Man of the United States, REXTA (REXTA)
C) and commercially available products such as UBETAC of Ube Industries, Ltd. can be used.

In the present invention, the crystalline polypropylene which is another component used as necessary as a component of the component (b ₂ ) is a polypropylene having an isotactic structure which is mostly insoluble in boiling n-heptane. And commercially available crystalline polypropylene for extrusion molding, injection molding, and blow molding can be used. This crystalline polypropylene may be a propylene homopolymer or a copolymer containing propylene and another α-olefin containing the component (b ₁ ). Usually, those having a density of 0.890 g / cm ³ or more are preferable.

The α-olefin used for copolymerization with propylene is, as described above, excluding propylene.
Α-olefins having 2 to 8 carbon atoms, for example, ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1 and the like. Among these, ethylene and butene-1 are particularly preferred.

Specific examples of the crystalline polypropylene include a propylene homopolymer and an ethylene component of 30% by weight.
Below, propylene containing preferably 1 to 25% by weight
A random or block copolymer of ethylene,
A random copolymer or block copolymer of propylene / butene-1 containing 20% by weight or less of butene-1; a ternary random copolymer or ternary block copolymer of propylene / ethylene / butene-1; Can be Among these, a copolymer of ethylene or butene-1 and propylene is particularly preferred. The crystalline polypropylene,
One type or a combination of two or more types can be used.

The crystalline polypropylene may be a commercially available product, or may be manufactured and used. The method for producing the crystalline polypropylene is not particularly limited, and it can be produced by a known method for producing a crystalline polypropylene. For example, magnesium, titanium, halogen atoms and electron donating compounds (eg, esters, thioesters, amines, ketones, nitriles, phosphines, ethers, thioethers, acid anhydrides, acid amides, organic silicon Oxygen, nitrogen,
A solid catalyst component comprising an organic compound containing phosphorus, sulfur, silicon, etc., an organoaluminum compound (trialkylaluminum, dialkylaluminum monohalide,
Alkyl aluminum sesquihalide, etc.), alkoxy group-containing aromatic compounds (mono-alkoxy aromatic compounds such as m-methoxytoluene, o-methoxyphenol, o-
A dialkoxy aromatic compound such as dimethoxybenzene and m-dimethoxybenzene, a trialkoxy aromatic compound such as 1,3,5-trimethoxybenzene, etc.) and, if necessary, an electron-donating compound. By a method such as a gas-phase one-stage polymerization method, a slurry one-stage polymerization method, a gas-phase multi-stage polymerization method, a slurry multi-stage polymerization method, and the like, propylene alone or propylene and the above-mentioned propylene are polymerized with an α-olefin having 2 to 8 carbon atoms. It is manufactured by

The amorphous polyolefin and the optionally used crystalline polypropylene are, for example, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid and itaconic acid. A known method using a biaxial kneader or the like using an acid and / or an ester thereof, an acid anhydride, a derivative such as a metal salt, an unsaturated amide, an amino compound, glycidyl methacrylate, or hydroxy methacrylate. Can also be used. Among these modified products, those modified with maleic anhydride and itaconic anhydride are preferable, and those modified with maleic anhydride are more preferable.

In the present invention, the resin composition (b ₂ )
As described above, the above-mentioned amorphous polyolefin alone or the above-mentioned amorphous polyolefin and the crystalline polypropylene, and the ratio of the amorphous polyolefin is 20 to 1
00% by weight, preferably 25-90% by weight, and the proportion of crystalline polypropylene is 80-0% by weight, preferably 75-10% by weight. When the proportion of the amorphous polyolefin is less than 20% by weight, it may be difficult to obtain flexibility and uniform stretchability. Amorphous polyolefin contributes to imparting flexibility and uniformity of stretching of the obtained multilayer film, and crystalline polypropylene contributes to increasing mechanical strength such as heat resistance and tensile modulus of the obtained multilayer film. .

In the present invention, the resin composition (b) comprising the amorphous polyolefin and crystalline polypropylene
The preparation method ₂ ) is not particularly limited, and may be a method commonly used in the production of a known polypropylene composition, for example, a kneader such as a kneader, a Banbury mixer, a roll, or a single-screw or twin-screw extruder. It can be performed by a method of melting and kneading under heating.

The polypropylene constituting the intermediate layer of the present invention
-Based resin (B) is the propylene-α-olefin
Dam copolymer (b₁) Or the resin composition (b)_Two),Previous
The low crystalline ethylene-α-olefin copolymer (a_Two)
And the antifogging agent (d) in a proportion as described above.
However, in addition to these, if necessary, the above (b)₁)
Minutes or the (b_Two) 100 parts by weight of the above-mentioned acid
0.01 to 0.5 part by weight of the antioxidant (e), preferably
0.02 to 0.2 parts by weight may be contained. This place
When the component (e) is contained in the polypropylene resin (B),
(A) so as to uniformly mix and disperse_Two) Component, low density
Polyethylene (a_Three) Or linear low density polyethylene
Ren (a_Four) Is used to prepare a masterbatch base with component (e).
It does not prevent use as a resin. The above (a)
_Two) Component, (a_Three) Component or (a) _Four) Component usage
Means that the content of the component (e) in the masterbatch is 3 to
10% by weight, preferably 3 to 8% by weight.
I just need.

Incidentally, the multilayer film for packaging of the present invention has a layer structure composed of at least five layers in which at least one adhesive layer exists between the surface layer and the intermediate layer. For example, surface layer (outer layer) / adhesive layer / intermediate layer / adhesive layer /
It consists of five layers, the surface layer (inner layer).

The ethylene resin (C) constituting the adhesive layer has a density of 0.910 to 0.945 g / cm ³ ,
Preferably 0.915 to 0.940 g / cm ³ ,
A main component is a linear low-density polyethylene (c ₁ ) having a melt index (MI _2.16 ) of 0.1 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min at 190 ° C. and a load of 2.16 kg. Is what you do.

The density of the component (c ₁ ) is 0.910 g /
If it is less than ³ cm ³ , the resulting film will have low rigidity and soft stiffness, and will also have poor heat resistance. On the other hand, when it exceeds 0.945 g / cm ³ ,
Not only is the mechanical strength of the resulting film, especially the impact strength, lowered, but also the stretchability is poor and the transparency may be poor, which is not preferred. If the component (c ₁ ) has an MI _2.16 of less than 0.1 g / 10 minutes, the melt viscosity is high and the moldability is poor.
If the time exceeds / 10 minutes, the melt viscosity is too low, resulting in poor moldability, and the mechanical strength of the obtained film is undesirably reduced.

Here, the component (c ₁ ) is an ethylene-α-olefin copolymer in which an appropriate number of short-chain branches are introduced into a linear main chain. Ziegler catalysts and chromium-based catalysts comprising a transition metal compound (compounds such as titanium and vanadium), an organometallic compound (eg, an organoaluminum compound) as a cocatalyst, and a carrier (eg, an oxide such as silicon, titanium, and magnesium). Is obtained by polymerizing ethylene and an α-olefin under medium or low pressure, or optionally under high pressure in the presence of The polymerization is performed by various methods such as slurry polymerization, gas-phase polymerization, and high-temperature dissolution polymerization.

The α-olefin copolymerized with ethylene is propylene, butene-1, pentene-1,
Hexene-1, heptene-1, octene-1, nonene-
Α- having 3 to 20 carbon atoms, such as 1, decene-1, dodecene-1, tetradecene-1, octadecene-1, 4-methylpentene-1, 4-methylhexene-1, and 4,4-dimethylpentene-1. Olefin or a mixture thereof is mentioned, and among them, α having 3 to 12 carbon atoms
-Olefins are preferred. The α-olefin content in these copolymers is preferably 20 mol% or less, more preferably 3 to 15 mol%.

In the present invention, (c)₁) Component
Have a density and melt index in the range described above.
In addition, the following characteristic (1) crystallinity (X-ray method) is 4
0 to 80%, (2) by differential scanning calorimeter (DSC)
There are multiple melting points to be measured
Of which the maximum melting point is in the range of 120 to 128 ° C,
And (3) the maximum heat of crystal fusion (H₁) And all crystal fusion
Calorific value (H_T) And 0 <H ₁/ H_THas ≦ 0.40
Are more preferably used. Specifically, Ultze
, Neozex (Mitsui Chemicals), Douret
Cousin (manufactured by Dow Chemical Company), NUC-Polyethylene-L
Commercial products such as L. and Toughsen (Nippon Unicar Co., Ltd.)
I can do it.

[0063] In the present invention, the ethylene-based resin constituting the adhesive layer (C), as described above, wherein at (c ₁₎ as a main component ingredients, specifically, the (c ₁ )) Based on 100 parts by weight of the base resin (C ₁ ) containing the component as a main component, 0.3 to 5 parts by weight, preferably 0.5 to 2 parts by weight of the antifogging agent (d), and an antioxidant ( e) in an amount of 0.01 to 0.5 part by weight, preferably 0.02 to 0.2 part by weight.
It is preferable to use one containing parts by weight. Here, the A (c ₁₎ the base resin (C ₁₎ composed mainly of components, the (c ₁₎ component per 100 parts by weight 3 to 20 parts by weight of low density polyethylene (a _3), preferably 5 to 15 parts by weight, and if necessary, a linear low-density polyethylene (a
_It is preferable that ₄ ) is contained in an amount of 1 to 5 parts by weight, preferably 2 to 4 parts by weight.

In the ethylene resin (C) constituting the adhesive layer of the present invention, the component (a ₃ ) contains the antifogging agent (d) in the ethylene resin (C) as in the case of both surface layers. It is used as a base resin of a master batch with the antifogging agent (d) so as to be uniformly mixed and dispersed. Therefore, if the amount of the component (a ₃ ) is less than 3 parts by weight based on 100 parts by weight of the component (c ₁ ), the anti-fogging effect may not be sufficiently exhibited. Conversely, when the component (a ₃ ) is more than 20 parts by weight based on 100 parts by weight of the component (c ₁ ), the mechanical strength, particularly the impact strength and the tear strength, of the film decreases, and the heat shrinkage stress decreases. When shrink wrapped, the film tends to be broken, the internal distortion causes curl and wrinkles, resulting in poor appearance, and the binding force is too strong and the packaged object tends to be deformed. Absent.

In the present invention, the component (a ₄ ) functions as a density adjuster for the entirety of the ethylene resin (C) constituting the adhesive layer, as in the case of the both surface layers. The antioxidant (e) is used as a master batch with the antioxidant (e) so that the antioxidant (e) is uniformly mixed and dispersed in the ethylene resin (C).
Therefore, if the compounding amount is less than 1 part by weight per 100 parts by weight of the component (c ₁ ), a film having low rigidity and a soft waist is obtained, and the effect of suppressing resin burning and gel generation during molding is sufficiently exhibited. It may not be done.
On the other hand, if the amount is more than 5 parts by weight per 100 parts by weight of the component (c ₁ ), the mechanical strength (particularly impact strength), low-temperature shrinkage, transparency and the like of the film tend to decrease.

Further, in the ethylene resin (C) constituting the adhesive layer of the present invention, the compounding amount of the antifogging agent (d) is 100% of the base resin (C ₁ ) containing the component (c ₁ ) as a main component.
If the amount is less than 0.3 part by weight, the antifogging property may be inferior. If the amount is more than 5 parts by weight, the film surface may be sticky, or may have poor blocking resistance, There is a possibility that the slipperiness with each other or with a metal may be deteriorated. Further, the antifogging agent may be dissolved in the cooling water during film formation, and there is a possibility that the problem of cooling water contamination such as generation of bubbles and deterioration of water quality may occur. Further, the amount of the antioxidant (e) added is such that the base resin (C ₁ ) containing the linear low-density polyethylene (c ₁ ) as a main component.
When the amount is less than 0.01 part by weight with respect to 100 parts by weight, the oxidation preventing effect of the ethylene-based resin (C) becomes small,
Resin scorching occurs during molding, and gels tend to be generated in the film. If the amount exceeds 0.5 parts by weight, the resulting film not only causes coloration or odor but also the antioxidant. (E) may bleed out over time and impair the appearance of the film.

In the present invention, in order to improve the slipperiness of the film, at least one of the ethylene-based resin (A) used for the surface layer, particularly the ethylene-based resin used for the outer layer which is not in direct contact with the packaged object. (A) may contain an antiblocking agent. As the antiblocking agent, a commonly used antiblocking agent can be used and is not particularly limited. Specifically, natural silica having an average particle diameter of 10μ or less, particularly 5μ or less, silica such as synthetic silica, synthetic silicone, average particle diameter of 20μ or less,
In particular, zeolite such as natural zeolite and synthetic zeolite having a size of 5 μm or less, talc, inorganic powder such as diatomaceous earth, kaolin, calcium silicate, aluminum silicate, magnesium silicate, calcium carbonate, higher fatty acid polyvinyl ester, n-octadecyl urea, dicarboxylic acid In addition to ester amides, N, N'-dioleyl oxamides, metal soaps, and organic powders such as organic polymers such as polyamide, polyester, and polycarbonate. Among them, silica, synthetic silicone, zeolite and talc are preferable, and synthetic silica, synthetic silicone and synthetic zeolite are particularly preferable.

The amount of the antiblocking agent to be added is 0.01 to 0.5 part by weight based on 100 parts by weight of the base resin (A ₁ ) mainly composed of the linear low density polyethylene (a ₁ ). I just need. If the amount is less than 0.01 parts by weight,
The effect of improving the slipperiness of the film may not be sufficiently exhibited. If the amount is more than 0.5 part by weight, the resulting film may have poor optical properties such as gloss and transparency. By adding the anti-blocking agent within the above range, the static friction coefficient of the ethylene resin (A) used for the surface layer (outer layer) becomes 0.40 or less,
The slipperiness of the multilayer film for packaging of the present invention is improved.

Further, the ethylene resin (A) constituting the both surface layers, the polypropylene resin (B) constituting the intermediate layer and / or the ethylene resin (C) constituting the adhesive layer according to the present invention are usually Heat stabilizers to be used, lubricants (higher fatty acid amides, higher fatty acid esters, waxes, etc.), antistatic agents (nonionic surfactants such as fatty acid esters of polyhydric alcohols, etc.) Cationic surfactants such as ionic surfactants, aliphatic amine salts and quaternary ammonium salts, amphoteric surfactants such as imidazoline type and betaine type, etc., nucleating agents (aromatic dicarboxylic acid, saturated aliphatic dicarboxylic acid) , Benzoic acid, dibenzylidene sorbitol, silicic anhydride, aluminum hydroxide, calcium carbonate, etc.), filler (alumina, clay, mica, titanium oxide) ), Coupling agents (silane-based, titanate-based, chromium-based, aluminum-based, etc.), tackifiers (castor oil derivatives, low-molecular viscous substances of polybutene, sorbitan higher fatty acid esters, etc.), dispersants (bisamides) Known dispersants, wax-based dispersants, organometallic salt-based dispersants, etc.), release agents, drip-free agents, antifouling agents, antibacterial agents, coloring agents (pigments, dyes, etc.). You may. Furthermore, other resins such as polyethylene wax, petroleum resin, terpene resin, cumarone-indene resin, rosin resin and hydrogenated derivatives thereof, or styrene / butadiene / styrene block copolymer or styrene of this hydrogenated product・ Ethylene / butylene / styrene block copolymer, styrene / isoprene
A styrene block copolymer, a hydrogenated styrene / ethylene / propylene / styrene block copolymer, ethylene propylene rubber, or a thermoplastic elastomer such as an ionomer may be contained. The amount of these additives is within a range that does not impair the properties of the obtained film, and is usually about 0.0005 to 5% by weight.

In the present invention, the ethylene-based resin (A), the polypropylene-based resin (B) and the ethylene-based resin (C) are each composed of the above-mentioned components (for example, the ethylene-based resin (A)). If present, the linear low-density polyethylene (a ₁ ), low-crystalline ethylene-α
- olefin copolymer (a _2), low density polyethylene (a _3), other anti-fogging agent (d) and antioxidant (e),
If necessary, it can be produced by mechanically mixing linear low-density polyethylene (a ₄ )) in the above-mentioned mixing ratio. As a method of mechanically mixing, for example, a method of dry blending using a commonly used mixer such as a tumbler or a Henschel mixer, or a Banbury mixer, a kneader, a roll mill and a screw type extruder (single screw extruder, A melt kneading method using a melt kneading machine such as a twin screw extruder, etc., may be mentioned, but it is necessary to pay sufficient attention so that each component does not cause poor dispersion during mixing. Note that the order of performing the mechanical mixing is not particularly limited.

In the above mechanical mixing, a more uniform composition can be obtained by dry-blending some components in advance and then melt-kneading the resulting mixture and the remaining components. Therefore, the anti-fogging agent (d), the antioxidant (e), and the like are used as the low-crystalline ethylene-α-olefin copolymer (a ₂ ), the low-density polyethylene (a ₃ ), or the linear low-polymer. A masterbatch is prepared in advance by dry blending with the high density polyethylene (a ₄ ), and the masterbatch and the remaining components are melt-kneaded to form a masterbatch such as the antifogging agent (d) and the antioxidant (e). It is preferable from the viewpoint of performing uniform dispersion and mixing in a short time. The composition of the master batch, if the anti-fogging agent (d), the component (d) and the (a ₂₎ component or the (a ₃₎ occupying in the total amount of component (d) the composition ratio of the components Is 0.1 to 2% by weight, preferably 0.5 to 1.5%
A range of weight% is preferred. In the case of antioxidant (e), antioxidant (e) and the (a ₄₎ the composition ratio of the antioxidant (e) in the total amount of the component is 3-10 wt%, preferably Is preferably in the range of 5 to 8% by weight. If the ratio of the component (d) and the component (e) in the masterbatch deviates from the above range, poor dispersion of the component (d) and the component (e) may cause an effect of improving anti-fogging property, or an effect at the time of film formation. There is a possibility that the effect of suppressing resin burning and gel generation may not be sufficiently exhibited.

Next, the multilayer film for packaging of the present invention is obtained by subjecting the ethylene resin (A), polypropylene resin (B) and ethylene resin (C) produced as described above to specific coextrusion molding. Depending on the layer structure of at least three types and five layers, for example, a laminate of ethylene-based resin (A) / ethylene-based resin (C) / polypropylene-based resin (B) / ethylene-based resin (C) / ethylene-based resin (A) The original film is formed, and then the film is biaxially stretched in both the longitudinal and transverse directions. There is no particular restriction on the order of stretching, which may be vertical or horizontal,
Vertical and horizontal simultaneous stretching may be used. Of these, simultaneous stretching in the vertical and horizontal directions is preferable, and simultaneous biaxial stretching in the tubular state is particularly preferable.

As the co-extrusion molding, a T-die molding method or a water-cooled inflation molding method is applied. That is, the above-mentioned ethylene-based resin (A), polypropylene-based resin (B) and ethylene-based resin (C) are each heated and melted by several extruders, and then, for example, 1
Extrusion is performed at an extrusion temperature of 90 to 210 ° C., and is usually used by rapidly cooling the melt-extruded resin by the above-described molding method, such as immediately quenching and solidifying with a liquid refrigerant such as cooling water into a tubular raw material. Compared with the air-cooled inflation molding method, a film having more excellent transparency and stretchability can be obtained. At the time of raw material forming, quenching can suppress the crystallinity to a low level, which improves transparency and stretchability. In the present invention, an air-cooled inflation molding method can be used. However, since the cooling effect is small, breakage at the time of stretching may occur, so that sufficient care is required. In particular, careful attention is required because the film is easily torn during stretching in the transverse direction. In the case of the water-cooled inflation molding method, cooling may be performed by contacting cooling water having a temperature of 50 ° C. or less, preferably 30 ° C. or less.

The unstretched multilayer film obtained by the co-extrusion molding is then biaxially stretched in both longitudinal and transverse directions of the film at a stretching ratio of 2 to 5 times, preferably 2.5 to 4.5 times. If the stretching ratio is less than 2 times, the strength of the film tends to be insufficient or the cutability tends to be insufficient. If the stretching ratio is more than 5 times, the stretchability decreases, and breakage or stretching unevenness in the film occurs. May occur
Either case is not desirable.

In the case of tubular simultaneous biaxial stretching, which is a preferred embodiment of the present invention, the unstretched multilayer film is heated as it is, for example, by changing the peripheral speed of a stretching roll to take up the film, ie, in the longitudinal direction. The film is simultaneously stretched in the transverse direction by blowing air into the film to change the diameter of the tubular film. At this time, the ratio of the stretching ratio in the longitudinal direction / the stretching ratio in the transverse direction is 0.9 to 1.5, preferably 1.1 to 1.
It is preferred to be in the range of 3. The internal pressure of the bubble depends on the diameter of the bubble and cannot be described unconditionally.
gG, more preferably in the range of 2 to 5 kgG. Note that the following equation (I) exists between the bubble internal pressure (mmH ₂ OG) and the gauge load (kgG).

[0076]

(Equation 1)

If the ratio of the stretching ratio in the longitudinal direction / the stretching ratio in the transverse direction is less than 0.9, the cutability of the film may be deteriorated, and if it exceeds 1.5, the balance of the film performance may be deteriorated. In addition, the bubble internal pressure is 1.5kg
If it is less than G, the stretching tension is reduced, the effect of stretching is reduced, and the strength and the low-temperature shrinkability of the film tend to be inferior. Thus, the frequency of rupture of the film, that is, puncturing of the bubble may increase, and even if the rupture does not occur, the film may be stretched unevenly.

The stretching temperature in the tubular simultaneous biaxial stretching treatment can be from room temperature (20 ° C.) to a temperature not higher than the melting point (T ₁ ° C.) of the polypropylene resin (B). In order to improve the low-temperature shrinkability and low-temperature heat-sealing property, it is preferable that the temperature is as high as possible within a range where uniform stretching can be performed. Therefore, the stretching temperature is usually 20 ° C. or higher and a temperature lower than T ₁ by about 10 ° C., preferably 100 ° C. or higher and T
A temperature range below about 20 ° C below ₁ is preferred,
Specifically, 100 to 130 ° C., preferably 100 to 12
Preferably it is 0 ° C. The stretching temperature mentioned here is a temperature at which the shrinkage stress of the film becomes maximum during stretching. Further, in order to increase the effect of preventing the film from shrinking over time, it is preferable to perform heat setting after stretching. The heat setting temperature is not particularly limited, but is preferably a temperature that does not cause wrinkles, and is usually 40 to 100 ° C, preferably 40 to 70 ° C, more preferably 40 to 60 ° C. .

In a preferred embodiment of the present invention, as described above, during the simultaneous biaxial stretching of the tube, the internal pressure of the bubble is made as high as possible and the film is stretched at a high temperature, so that excellent low-temperature shrinkage and low-temperature heat A film having a sealing property is obtained. Therefore, when the stretching temperature and the heat setting temperature are higher than the above-mentioned appropriate temperatures, not only the stability of the diameter of the tube is deteriorated, but also the low-temperature shrinkage may be reduced. If lower, the crystalline propylene- which is the main component of the polypropylene-based resin (B) used for the intermediate layer.
The α-olefin random copolymer (b ₁ ) or the resin composition (b ₂ ) comprising the amorphous polyolefin alone or the amorphous polyolefin and the crystalline polypropylene becomes difficult to stretch due to insufficient preheating, and the film In either case, it is not desirable because the rupture tends to occur.

In the present invention, in the stretching treatment of the unstretched multilayer film, a simultaneous biaxial stretching method of a tenter system or a sequential biaxial stretching method can be applied in addition to the simultaneous biaxial stretching method of the tubular system. . In this case, the stretching temperature and the heat setting temperature may be selected according to the above.

The overall thickness of the multilayer film for packaging of the present invention is not particularly limited, and may be appropriately selected depending on the type and form of the article to be packaged, but is generally about 5 to 50 μm. It is preferably about 5 to 30 μm, and more preferably about 8 to 25 μm.
If the total thickness of the multilayer film for packaging is larger than 50 μm, the tear strength at the time of cutting the film may be too large, which may make the film unsuitable for use in packaging films. On the other hand, if the total thickness is smaller than 5 μm, the stiffness of the film is lost and the film tends to be wrinkled, which may make the film unsuitable for packaging.

The thickness ratio of the two surface layers, the adhesive layer and the intermediate layer is not particularly limited either, and may be appropriately determined as long as the characteristics of the multilayer film for packaging of the present invention are not impaired. That is, the thickness of both surface layers is 0.1 to
About 10 μm is preferable, and the thickness of the adhesive layer is 0.5 to 15
It is preferably about μm. For the purpose of obtaining good film forming stability, the thickness of the intermediate layer made of the polypropylene resin (B) is preferably about 1 to 20 μm. For example,
In the case of a five-layer film, the thickness ratio of each layer is determined by the ratio of outer layer / adhesive layer /
Middle layer / adhesive layer / inner layer = (1 / 1.5 / 0.7 / 1.5
/ 1) to (1/2/3/2/1) may be determined within the above thickness range.

The multilayer film for packaging of the present invention obtained as described above comprises: (1) The linear film produced by using a single-site catalyst as a main component of the ethylene resin (A) in both surface layers. Using low-density polyethylene (a ₁ ), and as a main component of the intermediate layer, crystalline propylene-α-olefin random copolymer (b ₁ ) alone, or amorphous polyolefin alone or amorphous polyolefin and crystalline The resin composition (b) comprising polypropylene
By using ₂ ), the crystallinity of the entire film is reduced, the peel strength at the laminating interface of the film is increased, and a low-temperature, high-sealing strength is provided. (2) The ethylene-based resin (C ), The density of the linear low-density polyethylene (c ₁ ) (0.910 to 0.945 g / c).
m ³ ) is the density of the linear low-density polyethylene (a ₁ ) which is the main component of the ethylene-based resin (A) in both surface layers (0.
880-0.910 g / cm ³ )
Microwave oven resistance, that is, imparting heat resistance, and (3) In the biaxial stretching operation at the time of film forming, particularly in the simultaneous biaxial stretching operation of the tubular, the internal pressure of the bubble is increased as much as possible (1.5 to 1.5). 7 kgG) and by raising the stretching temperature (100 to 130 ° C.), it has properties such as low-temperature shrinkage and low-temperature heat-sealing properties.

Accordingly, the multilayer film for packaging of the present invention has the following physical properties. That is, it is preferable that the haze value is 1.5% or less, preferably 1% or less, and the gloss value is 130% or more, preferably 140% or more. The haze value of the film is 1.5%
If it exceeds, the transparency is reduced and the display effect of the packaged object is small. When the gloss value of the film is less than 130%, the gloss is lost, the film surface becomes whitish, and the quality of the packaged object is lost. In addition, temperature 100
Thermal shrinkage in both longitudinal and transverse directions at 25 ° C is 25%
And preferably at least 30%. If it is less than 25%, the adhesiveness of the film after heat shrinkage to the packaged object during shrink packaging is poor, which may cause wrinkles. In addition, both vertical and horizontal tear strength are 2kg.
/ Cm or more, preferably 3 kg / cm or more. If the tear strength is lower than the lower limit, the film tends to be torn when the film is mounted in a packaging operation by a packaging machine, which is not preferable.

Further, the surface layers are sealed with a sealing pressure of 1 k.
g / cm ² G, a sealing temperature of 90 ° C., and a sealing time of 1 second, when a film having a width of 15 mm obtained by peeling in a direction of 180 ° at a pulling speed of 100 mm / min has a peeling resistance of 100 g / 15 mm or more. , Preferably 120 g / 15 mm or more. If the peeling resistance is less than 100 g / 15 mm, the bottom seal of the tray-packed product becomes poor, the suitability for high-speed filling and packaging is poor, and the production speed of the packaged product cannot be increased. In addition, shrinkage (curling) and wrinkles occur during heat sealing.

The multilayer film for packaging of the present invention comprises raw meat,
It is used for food tray pack packaging of processed meats, fish, lunches, prepared foods, refrigerated / frozen foods and the like, and various other packaging applications, and is particularly suitably used for folding pillow packaging.

[0087]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples unless it exceeds the gist thereof. In the following examples, physical properties of the obtained films were measured by the following methods.

(1) Transparency (haze) Measured according to a method according to ASTM D1003.

(2) Glossiness Gloss was measured on each of the inner layer surface and the outer layer surface by a method according to ASTM D523.

(3) Heat Shrinkage In accordance with JIS Z1703, the heat shrinkage at a temperature of 100 ° C. was measured in the longitudinal and transverse directions of the film, respectively.

(4) Tear Strength The tear strength was measured in the longitudinal and transverse directions of the film by a method according to JIS K6772.

(5) Tensile Strength, Elongation and Elastic Modulus Using a universal tester ABS100B manufactured by Shimadzu Corporation, using a JIS No. 1 test piece, the film was measured in the longitudinal and transverse directions, respectively. The tensile strength and elongation were measured at a tensile speed of 100 mm / min, and the elastic modulus was measured at a tensile speed of 5 mm / min.

(6) Low Temperature Heat Sealability A rectangular test piece having a width of 15 mm was cut out, and the surface layers thereof were sealed with a heat sealer at a sealing pressure of 1 kg / cm ^2.
G, after heat-sealing under the conditions of a sealing temperature of 90 ° C. and a sealing time of 1 second, a peeling resistance (g / 1
5 mm).

(7) Slipperiness The film was aged in an air oven at 40 ° C. for 24 hours according to ASTM D1894, and then the static friction coefficient and the dynamic friction coefficient of the film surface layer (outer layer) were measured.

Example 1 [Preparation of Resin Composition (b ₂ ) Used in Intermediate Layer] As a raw material resin shown in Table 2, as a resin composition (b ₂ ) used in the intermediate layer, an amorphous polyolefin ( Propylene-butene-1 copolymer manufactured by Ube Industries, Ltd., trade name:
Ubetac UT2780, propylene content: 65% by weight, butene-1 content: 35% by weight, density: 0.86
g / cm ³ , boiling n-heptane insoluble matter: 5% by weight, crystallinity: 6%) and crystalline polypropylene (manufactured by Grand Polymer Co., Ltd., trade name: F226D, density: 0.91 g)
/ Cm ³ ) at a weight ratio of 30/70, and to 100 parts by weight of this mixture, 0.05 part by weight of oleamide was added and melt-kneaded at a temperature of 200 ° C. for 30 minutes.
A resin composition prepared by pelletizing was used.

[Production of tubular laminated unstretched film]
Next, the ethylene resin (A), the polypropylene resin (B) and the ethylene resin (C) obtained by melt-kneading the raw material resins shown in Tables 1 and 2 using four 50 mmφ extruders were used. The diameter 14 connected to these extruders
It was melt-extruded at an extrusion temperature of 200 ° C. downward from a 1 mmφ 5-layer co-extrusion annular die. Subsequently, while sliding the outer surface of the cylindrical mandrel in which the extruded molten tubular film is mounted directly below the annular die and circulating cooling water at 20 ° C. inside, the outside is passed through a water tank. After cooling to water and cooling to room temperature, it is taken out, and the outer layer [ethylene resin (A)] / adhesive layer [ethylene resin (C)] / intermediate layer [polypropylene resin (B)] / adhesive layer [ethylene resin (C) ] / Inner layer [ethylene resin (A)] to obtain a tubular laminated unstretched film composed of five layers. The overall thickness of this tubular laminated unstretched film is about 210 μm, and the thickness ratio of each layer is about 1: 1.7 from one surface layer.
5: 2.5: 1.75: 1. Tables 1 and 2 show the composition of each raw material used. In addition, outer layer, inner layer,
Intermediate layer and masterbatch used as a raw material resin for the adhesive layer (MB ₁₎ in advance using a Henschel mixer, a phenolic antioxidant and a phosphorus antioxidant, and a linear low density polyethylene (a ₄₎ Those manufactured by dry blending at the composition ratios shown in Tables 1 and 2 were used.

[0097]

[Table 1]

[0098]

[Table 2]

As the raw materials shown in Tables 1 and 2,
The following were used. (1) Linear low-density polyethylene (a ₁ ): linear low-density polyethylene, UBE Polyethylene S, manufactured by Ube Industries, Ltd.
PE0540F (trade name), MI _2.16 ; 4.0 g / 10
Min, density; 0.903g / cm ³ (2) low-crystalline ethylene -α- olefin copolymer (a
₂ ): Propylene-butene-1 copolymer manufactured by Mitsui Chemicals, Inc., Tuffmer A4085 (trade name), MI _2.16 ; 4.0
g / 10 minutes, density: 0.890 g / cm ³ , Vicat softening point: 55 ° C. (3) Low-density polyethylene (a ₃ ): Ube Industries, Ltd. High-pressure low-density polyethylene, UBE polyethylene F222
N (trade name), MI _2.16 ; 2.0 g / 10 min, density;
0.922 g / cm ³ (4) Linear low-density polyethylene (a ₄ ): Ube Industries, Ltd. Linear low-density polyethylene, UBE polyethylene S
PE1540F (trade name), MI _2.16 ; 4.0 g / 10
Min, density; 0.915g / cm ³ (5) linear low density polyethylene (c _1): Mitsui Chemicals Co. linear low density polyethylene, ULTZEX 2
023L (trade name), MI _2.16 ; 2.3 g / 10 min, density: 0.920 g / cm ³ (6) Glycerin condensed polymer fatty acid ester: diglycerin laurate (manufactured by Marubishi Yuka Kogyo Co., Ltd.) 7) Glycerin monofatty acid ester: glycerin monooleate (manufactured by Marubishi Yuka Kogyo Co., Ltd.) (8) Polyoxyethylene alkyl ether: polyoxyethylene lauryl ether (manufactured by Marubishi Yuka Kogyo Co., Ltd.) (9) Phenolic antioxidant: Irganox 107
6 (trade name) (manufactured by Ciba Geigy) (10) Phosphorus antioxidant: PEPQ (trade name) (manufactured by Clariant Japan)

Subsequently, the unstretched film was guided to a tubular biaxial stretching device, and was heated from the outside by an annular infrared heater provided near the entrance of the device to reduce the stretching temperature to 10 °.
While the temperature was set to 7 ° C., pressurized air was sent into the inside of the tubular film to adjust the bubble internal pressure (gauge load) to 4.3 kgG, and by adjusting the peripheral speed ratio of the low-speed and high-speed nip rolls, 4.7 times in the vertical direction. Expansion stretching was performed in the transverse direction at a stretching ratio of 3.8 times. Therefore, the ratio of the stretching ratio in the longitudinal direction / the stretching ratio in the transverse direction was 1.24. The thus obtained tubular stretched film is folded, drawn out of the stretching device, further guided to a heat fixing device, and subjected to 50
Heating was performed for 15 seconds by injecting hot air at ℃. The thickness of this film was 13.0 μm. Further, the transparency (haze), gloss (gross), heat shrinkage, tear strength, tensile strength, elongation, elastic modulus, low-temperature heat sealability, and slipperiness of the film were evaluated by the methods described above. Result is,
As shown in Tables 3 and 4.

Example 2 A crystalline propylene-α-olefin shown in the following (1) was used in place of 100 parts by weight of the resin composition (b ₂ ) used as one component of the polypropylene resin (B) constituting the intermediate layer. 100 parts by weight of the random copolymer (b ₁ ) were used, and the linear low-density polyethylene (c) used as one component of the ethylene resin (C) constituting the adhesive layers (the second and fourth layers) ₁ ) 100 parts by weight of the linear low-density polyethylene (c ₂ ) shown in (2) below was used instead of 100 parts by weight, and the thickness ratio of each layer in the tubular laminated unstretched film was determined by comparing From about 1: 1.75:
About 1: 1.75: 0.7 instead of 2.5: 1.75: 1
5: 1.75: 1, the stretching ratio in the longitudinal direction was changed from 4.7 times to 4.3 times, and the stretching ratio in the transverse direction was 3.8 times to 4. 0 times, therefore, the ratio of the longitudinal stretching ratio / lateral stretching ratio was changed from 1.24 to 1.08, the stretching temperature was changed to 107 ° C. to 113 ° C., and the bubble internal pressure ( Gauge load) to 4.3kgG and 2.2kgG
A film was formed in exactly the same manner as in Example 1 except that the film thickness was adjusted. Tables 3 and 4 show the evaluation results such as the performance of the film. (1) Crystalline propylene-α-olefin random copolymer (b ₁ ): Propylene-ethylene random copolymer manufactured by Grand Polymer Co., Ltd., PPF232DC (trade name), density: 0.905 g / cm ³ , melt Flow rate (230 ° C, 2.16 kg load); 2.7 g / 10
Min, ethylene content; 4.0% by weight, Vicat softening point;
123 ° C., cold xylene soluble part (20 ° C.); 9.4% by weight (2) Linear low density polyethylene (c ₂ ): Dow Chemical Co., Ltd. Linear low density polyethylene, Dourex 2
047AC (trade name), MI _2.16 ; 2.3 g / 10 minutes,
Density; 0.917 g / cm ³

Comparative Example 1 The resin composition for forming the adhesive layers (the second and fourth layers) was changed to ethylene resin (A) instead of ethylene resin (C). Temperature 107
The film was formed in exactly the same manner as in Example 1 except that the temperature was changed to 96 ° C instead of ° C, and the internal pressure (gauge load) was adjusted to 2.5 kgG instead of 4.3 kgG. Tables 3 and 4 show the evaluation results such as the performance of the film.

As is clear from Table 4, a film having a width of 15 mm obtained by heat sealing the surface layers at a sealing pressure of 1 kg / cm ² G, a sealing temperature of 90 ° C. and a sealing time of 1 second was applied at a pulling speed of 100 mm / min. The peel resistance when peeled in the direction of 180 degrees was 0 g / 15 mm, and it was found that the obtained film had no low-temperature heat sealability. This is the surface layer (inner and outer layers)
And a low-crystalline ethylene- adhesive layer (second and fourth layers).
Since the ethylene-based resin (A) containing a large amount of the α-olefin copolymer was used, the crystallinity of the entire film was too low and the film was too soft. As a result, the stretching temperature was adjusted to an appropriate range of 100 to 130 ° C. It is considered that it could not be held.

[0104]

[Table 3]

[0105]

[Table 4]

[0106]

As described above, the multilayer film for packaging according to the present invention comprises both surface layers composed of an ethylene resin mainly composed of linear low-density polyethylene produced using a single-site catalyst, and crystalline propylene-α- A resin composition comprising an olefin random copolymer alone or an amorphous polyolefin alone or an amorphous polyolefin and a crystalline polypropylene, and an intermediate comprising a polypropylene resin containing a low crystalline ethylene-α-olefin copolymer Between the layers, an adhesive layer composed of another ethylene-based resin mainly composed of a linear low-density polyethylene having a higher density than a linear low-density polyethylene that is a main component of the ethylene-based resin constituting the both surface layers. A layer structure in which at least one layer is present, preferably by stretching at a temperature of 100 to 130 ° C. during the stretching process. It has excellent low-temperature shrinkability, high transparency, high gloss, good tear strength, low-temperature high seal strength, and excellent heat resistance, and burns off the film during heat sealing or heating with a microwave oven. It is an excellent film which does not cause any occurrence of cracks. Therefore, raw meat, processed meat, fish, bento, side dishes, refrigerated
It can be suitably used for folding pillow packaging for tray pack packaging of foods such as frozen foods. Furthermore, since the multilayer film for food packaging of the present invention is composed entirely of a polyolefin-based resin, there is no generation of toxic gas at the time of incineration, no generation of highly toxic combustion residues, and no environmental problems. It is also excellent in safety from such factors.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23/12 C08L 23/12 23/14 23/14 F term (Reference) 3E086 AD01 AD08 BA15 BB22 BB31 BB41 BB51 BB67 BB85 CA01 4F100 AK06 AK07C AK62A AK62B AK63A AK63B AK63G AK66C AK67C AL03C AL05A AL05B AL05C BA03 BA06 BA10A BA10B CA06A CA06B CA06G CA06H CA10A CA10B CA10C CA10G CA10H CA19 EH20 EJ38 EJ50 GB15 JA03 JA11C JA12C JK06 JN01 JN21 YY00A YY00B 4J002 BB031 BB033 BB052 BB121 BB141 BB152 CH024 EH046 EH056 EJ027 EJ037 EJ047 EW068 FD077 FD078 FD204 FD206 GF00 GG02

Claims (3)

[Claims] (1) a density of 0.880 to 0.910 g / cm;
³ , a melt index of 0.5 to 20 g / 10 min, both surface layers of an ethylene resin (A) containing a linear low density polyethylene (a ₁ ) as a main component, and propylene-α-
When the content of the olefin random copolymer (b ₁ ) or the propylene component and / or the butene-1 component is 50,
Intermediate layer made of a polypropylene resin (B) containing as a main component a resin composition (b ₂ ) containing 20 to 100% by weight of an amorphous polyolefin of at least 20% by weight and 80 to 0% by weight of a crystalline polypropylene. Between 0.910
0.945 g / cm ³ with a melt index of 0.1 to
A biaxially stretched film comprising at least five layers, wherein at least one adhesive layer comprising an ethylene-based resin (C) containing 10 g / 10 min of a linear low-density polyethylene (c ₁ ) as a main component, The haze value of the film is 1.5% or less, the gloss value is 130% or more, the heat shrinkage in the longitudinal direction and the transverse direction at a temperature of 100 ° C. are both 25% or more, and the tear strength in the longitudinal direction and the transverse direction is Both are 2kg / c
m and the sealing pressure between the surface layers is 1 kg /
When a film having a width of 15 mm obtained by heat sealing at ² cm, a sealing temperature of 90 ° C. and a sealing time of 1 second is peeled in a direction of 180 ° at a pulling speed of 100 mm / min, the peeling resistance is 100 g / 15 mm or more. Multilayer film for packaging. 2. A linear low-density polyethylene (a ₁ ) 100 in which both surfaces of the ethylene resin (A) have a density of 0.880 to 0.910 g / cm ³ and a melt index of 0.5 to 20 g / 10 min. Density per part by weight 0.870-0.90
5 g / cm ³ , melt index 0.1 to 10 g / 1
A base mainly composed of the linear low-density polyethylene (a ₁ ) containing 20 to 50 parts by weight of a low-crystalline ethylene-α-olefin copolymer (a ₂ ) having 0 minutes and a Vicat softening point of 80 ° C. or lower. 0.3 to 5 parts by weight of antifogging agent and 0.01 to 0.1 part by weight of antioxidant based on 100 parts by weight of resin (A ₁ ).
5 parts by weight, and the polypropylene resin of the intermediate layer (B) is a propylene-α-olefin random copolymer (b ₁ ) or a propylene component and / or
Or a resin composition (b) containing 20 to 100% by weight of an amorphous polyolefin having a butene-1 component content of 50% by weight or more and 80 to 0% by weight of a crystalline polypropylene;
₂ ) 100 parts by weight of the low crystalline ethylene-α-
5 to 40 parts by weight of the olefin copolymer (a ₂ ) and 0.3 to 5 parts by weight of the antifogging agent, and the ethylene resin (C) of the adhesive layer has a density of 0.910 to 0 .9
Melt index of 0.1 to 10 g / at 45 g / cm ³
10 minutes of linear low density polyethylene base resin (C ₁₎ to (c ₁₎ as a main component antifog agent 0.3 to 5 parts by weight of antioxidant per 100 parts by weight of 0.01 to 0. The multilayer film for packaging according to claim 1, wherein the multilayer film contains 5 parts by weight. 3. A density of 0.880 to 0.910 g / cm.
³ , a melt index of 0.5 to 20 g / 10 min, both surface layers of an ethylene resin (A) containing a linear low density polyethylene (a ₁ ) as a main component, and propylene-α-
When the content of the olefin random copolymer (b ₁ ) or the propylene component and / or the butene-1 component is 50,
Intermediate layer made of a polypropylene resin (B) containing as a main component a resin composition (b ₂ ) containing 20 to 100% by weight of an amorphous polyolefin of at least 20% by weight and 80 to 0% by weight of a crystalline polypropylene. Between 0.910
0.945 g / cm ³ with a melt index of 0.1 to
After coextruding a laminate of at least 5 layers having at least one adhesive layer composed of an ethylene-based resin (C) containing 10 g / 10 min of a linear low-density polyethylene (c ₁ ) as a main component, it is quenched. To obtain a raw film, and then, the raw film has a ratio of the stretching ratio in the longitudinal direction / the stretching ratio in the lateral direction of 0.9 to 0.9%.
2. A tubular biaxially-stretched film is stretched 2 to 5 times in the longitudinal and transverse directions under conditions of 1.5 and a stretching temperature of 100 to 130 ° C., respectively, and further heat-set at a temperature of 40 to 100 ° C. Or the multilayer film for packaging according to 2.