JPH0852844A - Laminate resin film - Google Patents

Abstract

PURPOSE:To provide a stretch packaging laminate resin film of excellent resistance to heat, adequate fiber permeability and gas permeability and of excellent interlaminar bonding force. CONSTITUTION:A laminate resin film is formed by laminating an ethylene-vinyl acetate copolymer (B1) of 80-99.5wt.% containing vinyl acetate of 5-40wt.%, an ethylene resin film layer (B) containing a terpolymer (B2) of 20-0.5wt.%, composed of (a) ethylene of 66-98wt.%, (b) acrylic acid lower alkyl ester (1-4C alkyl) of 1-30wt.% and (c) maleic anhydride of 1-4wt.%, on one surface or both surfaces of a polyamide resin film (A).

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 packaging foods, and more particularly to a laminated resin film having excellent heat resistance, moderate water vapor permeability and gas permeability, and excellent interlayer adhesion.

[0002]

2. Description of the Related Art In recent years, foods such as fruits and vegetables, fresh fish, fresh meats, side dishes, etc. are placed directly or on a plastic tray, and these are stretch-wrapped with a film, so-called pre-packaging film, which is environmentally friendly. Instead of a conventional polyvinyl chloride film, a linear low-density polyethylene film (Japanese Patent Laid-Open No. 64-14018) or a linear low-density polyethylene is used as an intermediate layer, and an ethylene / vinyl acetate copolymer film is formed on the front and back surfaces. Laminated three-layer film (Japanese Patent Publication No. 2-18953, JP-A-3-258542)
No.), a high-density polyethylene film as an intermediate layer, and a high-pressure low-density polyethylene film is laminated on the front and back surfaces of the film to form a three-layer structure (JP-A-57-210853).
No.) and other packaging films based on ethylene resin have been put to practical use. This product is used for packaging fruits and vegetables, meat, and prepared foods, but mushrooms such as mushrooms, shiitake mushrooms and shimeji mushrooms, which are required to have high water vapor permeability in vegetables and vegetables, and prepared foods that are reheated in a microwave oven, are also used. Is not enough as a film for stretch packaging.

For the purpose of improving these drawbacks, Japanese Patent Laid-Open No.
In JP-A 3-56065, the bending elastic modulus is 10,000.
On at least one side of a film composed of a homopolymer or copolymer resin of ω-laurolactam of not more than kg / cm ² ,
(A ') ethylene having a vinyl acetate content of 5 to 25% by weight
94 to 99.8% by weight of vinyl acetate copolymer resin or 1.2 polybutadiene resin and (B ') sorbitan fatty acid ester and its ethylene oxide adduct, mono- and polyglycerin fatty acid ester, sucrose fatty acid ester, glycerin ricinoleic acid ester And selected from glyceryl acetyl ricinoleate 0.2 to 6% by weight
A laminated stretch packaging film in which a resin film containing is laminated is described. However, since the stretch packaging film has poor adhesiveness between the intermediate layer and the surface layer, when unwinding the laminated film or when packaging the product with an automatic packaging machine, delamination may occur,
Practicality is poor.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stretch wrapping film which has excellent heat resistance, proper water vapor permeability and gas permeability, and excellent interlaminar adhesion.

[0005]

The present invention relates to an ethylene / vinyl acetate copolymer (B having a vinyl acetate content of 5 to 40% by weight) on one or both sides of a polyamide resin film (A).
₁ ) 80-99.5 wt% and (a) ethylene 66-9
A terpolymer (B ₂ ) containing 8% by weight, (b) 1 to 30% by weight of a lower alkyl ester of acrylic acid (having 1 to 4 carbon atoms in the alkyl group) and (c) 1 to 4% by weight of maleic anhydride. ) The present invention provides a laminated resin film comprising an ethylene-based resin film layer (B) containing 20 to 0.5% by weight.

[0006]

[Function] A laminated resin film having a polyamide resin layer imparts heat resistance and appropriate water vapor permeability and gas permeability, and the presence of an ethylene / acrylic acid lower alkyl ester / maleic anhydride copolymer has a high interlayer adhesive strength. Is obtained.

(Detailed Description of the Invention) As the polyamide resin of the base material layer of the laminated resin film of the base material layer (A) packaging material, nylon 6, nylon 11, nylon 12, nylon 66, nylon 610 and nylon 12 are used. / 6 copolymer, nylon 6/66 copolymer, nylon 6/66/1
2 A highly crystalline polyamide resin such as a copolymer and a melting point of 1
Copolymer elastomer of polyoxyalkylene glycol having a density of 1.01 to 1.02 g / cm ² at 45 to 180 ° C. and ω-laurolactam [eg, E40, E47, E45, E45 of Daiamide-PAE manufactured by Daicel Hüls.
62 and X4442. All of them are used alone or in combination of two or more. Above all, nylon 6
/ 66 copolymer, melting point 182-by differential scanning calorimeter
Nylon 12/6 copolymer at 196 ° C. is preferable in terms of improving packaging suitability. Nylon 12/6 copolymer, Nylon 12 is called Nylon 12, and for example, Daicel
It is sold under the trade name of DAIAMID by the Hüls corporation.

For the purpose of improving packaging suitability, the base material layer (A) contains an ethylene / vinyl acetate copolymer (vinyl acetate content of 5 to 30% by weight), an ethylene / acrylic acid copolymer (acrylic acid). 5-20% by weight), ethylene
A metal salt of a copolymer of a methyl methacrylate copolymer, an α-olefin such as ethylene and propylene, and a monomer selected from acrylic acid, methacrylic acid, maleic acid and the like (Z
n, Na, K, Li, Mg, etc.), density 0.890-
0.910 g / cm ³ , melt index of 0.1
10g / 10min low density polyethylene, density 0.88
6 to 0.920 g / cm ³ linear low density polyethylene,
Maleic anhydride-grafted ethylene / vinyl acetate copolymer, maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, ethylene / ethyl acrylate / maleic anhydride terpolymer, etc., or 2
1 to 40% by weight, preferably 10 to 35% by weight, may be blended.

Surface layer (B) The ethylene resin film (B) for the surface layer, which is laminated on one side or both sides of the base material layer (A) of the polyamide resin film, comprises ethylene having a vinyl acetate content of 5 to 40% by weight. -Vinyl acetate copolymer (B ₁ ) 80 to 99.5% by weight
And (a) 66 to 98% by weight of ethylene, (b) lower alkyl ester of acrylic acid (wherein the carbon number of the alkyl group is 1 to
4) 1 to 30% by weight and (c) maleic anhydride 1 to 4
It is a resin film (B) containing 20 to 0.5 wt% of a terpolymer (B ₂ ) with wt%. The ethylene / vinyl acetate copolymer (B ₁ ) preferably has a vinyl acetate content of 5 to 25% by weight, and has an MFR (JIS K-72).
10; 190 ° C, 2.16 kg load) is 0.1-10 g
/ 10 minutes is preferable in terms of moldability and tackiness. This ethylene / vinyl acetate copolymer (B ₁ ) contains ethylene / acrylic acid lower alkyl ester (B ₁ ) in order to strengthen the adhesive force with the polyamide resin film substrate layer (A).
A maleic anhydride terpolymer (B ₂ ) is blended.

Examples of lower alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, and n-butyl acrylate. This ternary copolymer has a constitutional unit concentration of ethylene in the copolymer component of 66 to 98% by weight, preferably 71 to 94% by weight, and a constitutional unit concentration of lower alkyl acrylate is 1 to 30% by weight. , Preferably 4 to 25% by weight, the concentration of maleic anhydride constituting unit is 1 to 4% by weight, preferably 2 to
4% by weight. Preferably, MFR (JIS
K-6730) is 1 to 40 g / 10 minutes, more preferably 2 to 10 g / 10 minutes, and the density is 0.925 to 0.950 g.
/ Cm ³ , Vicat softening point (JIS K-6730) is 36 to 94 ° C, and more preferably 65 to 94 ° C. Such a terpolymer (B ₂ ) is available from Sumitomo Chemical Co., Ltd. as FX-800U and LX411 of Bondine.
0, TX8030, AX8060, and AX8390 are available as trade names. The proportion of this terpolymer (B ₂ ) in the surface layer (B) is 0.5 to 10% by weight, preferably 2 to 5% by weight, from the viewpoints of preventing blocking, improving adhesive strength, and moldability. is there.

The ethylene-based resin film (B) facilitates inflation molding of the laminated resin film, and improves the adhesiveness of the laminated resin film or the fitting property to a tray for storing mushrooms. The ethylene resin (B) of the surface layer of the laminated resin film has antifogging property,
And in order to impart appropriate slipperiness, self-adhesiveness and antistatic property, for example, the carbon number is 1 to 12, preferably 1 to
An aliphatic alcohol fatty acid ester which is a compound of an aliphatic alcohol of 6 and a fatty acid of 10 to 22 carbon atoms, preferably 12 to 18 carbon atoms, specifically, monoglycerin oleate, polyglycerin oleate, glycerin trilyl Cinoleate, glycerin acetyl ricinoleate, polyglycerin stearate, polyglycerin laurate,
Methyl acetyl ricinoleate, ethyl acetyl ricinoleate, butyl acetyl ricinoleate, propylene glycol oleate, propylene glycol laurate, pentaerythritol oleate, polyethylene glycol oleate, polypropylene glycol oleate,
0.1-5% by weight of sorbitan oleate, sorbitan laurate, polyethylene glycol sorbitan oleate, polyethylene glycol sorbitan laurate, etc., and at least one of polyalkylene ether polyols, specifically polyethylene glycol, polypropylene glycol, etc. %, Preferably 1 to 4% by weight. Moreover, you may mix | blend the said additive with 0.1-10 weight% of polyamide resin base material layer (A). Further, a freshness-retaining agent such as hinokitiol or zeolite may be added to the surface layer and the base material layer for the purpose of sterilization, mildew proofing, ethylene adsorption and the like.

Laminated Film The laminated resin film for stretch packaging of the present invention comprises the above-mentioned polyamide resin (A) and ethylene-based resin composition (B).
Are laminated and molded by a known method such as a multi-layer inflation molding or a co-extrusion method by T die molding or an extrusion laminating method using a plurality of extruders. Among them, coextrusion by inflation molding is preferable in order to obtain a laminated film in which mechanical strength such as tear strength in the machine direction and the transverse direction is well balanced, and the blow ratio at that time is 3 to 20 times, preferably 5 to 18 times. Double. The blow ratio here means a ratio of the circumferential length of the final blown film to the circumferential length of the die slit of the die. The thickness of each layer of the laminated resin film is 8 to 30 μm in total thickness, of which the base material layer (A) is 2 to 10 μm and the surface layer (B) is 3 to 1 μm, respectively.
It is preferably 0 μm.

This laminated resin film has a water vapor permeability of 80 to 1,000 g / m ² · 24 hours · atm, an oxygen permeability of 300 to 28,000 cc / m ² · 24 hours · atm, and a carbon dioxide gas permeability. Is 1,000-40,000
cc / m ² · 24 hours · atm, preferably water vapor permeability of 200 to 600 g / m ² · 24 hours · atm, oxygen permeability of 400 to 11,000 cc / m ² · 24 hours ·
atm, carbon dioxide permeability of 2,000 to 35,000 c
c / m ² · 24 hours · atm, more preferably water vapor permeability of 200 to 600 g / m ² · 24 hours · atm,
Oxygen permeability 400 to 8,000 cc / m ² · 24 hours · atm, carbon dioxide permeability 2,000 to 35,000
cc / m ² · 24 hours · atm is preferable for mushroom packaging. The laminated film for packaging of the present invention is suitable for packaging mushrooms such as shiitake mushrooms and shimeji mushrooms, and side dishes.
It is also suitable as a film for gas displacement packaging for the purpose of maintaining the accuracy of fresh meat, fresh fish and the like.

[0014]

【Example】

Example 1 Nylon 12/6 copolymer [density 1.02 g / cm ³ ,
Melting point 155 ° C .; trade name “DAIAMIDE N1901” manufactured by Daicel Hüls Ltd.] (A), diameter 65 m
m, L / D25 extruder was used to knead at 200 ° C., while ethylene / vinyl acetate copolymer resin [vinyl acetate content 15% by weight, density 0.938 g / cm ³ , melting point 97
C; manufactured by Mitsubishi Petrochemical Co., Ltd., trade name "Mitsubishi Poly-EVA"
41H "] 95.5% by weight, MFR ³ g / 10 minutes, density 0.94 g / cm ³ , melting point 95 ° C, Vicat softening point 68
C. Ethylene / ethyl acrylate / maleic anhydride terpolymer resin (manufactured by Sumitomo Chemical Co., Ltd., trade name “Bondaine TX8030”) 3.0% by weight and sorbitan oleate [manufactured by Riken Vitamin Co., trade name "Riquemar O250"] 1.5% by weight of a resin composition (B)
170 with an extruder with a diameter of 50 mm and L / D25
Kneading at 0 ° C., and supplying both of them to a single annular three-layer die, on both sides of the resin layer of (A) having a thickness of 3 μm,
The resin layer of (B) having a thickness of 5 μm is laminated, and inflation molding is performed at a die temperature of 200 ° C. and a blow ratio of 10 times to obtain a total thickness of 13 μm (5 μm).
/ 3 μm / 5 μm) to produce a laminated resin film for stretch packaging. The physical properties and practicality of this film are shown in Tables 1 and 2.

Example 2 As the surface layer resin (B), 95.5% by weight of the ethylene / vinyl acetate copolymer resin used in Example 1 and ethylene.
Ethyl acrylate / maleic anhydride terpolymer resin [MFR 5 g / 10 minutes, density 0.93 g / cm ³ , melting point 107 ° C .; Sumitomo Chemical Co., Ltd., trade name “Bondaine LX4110”] 3.0% by weight Also, a laminated resin film for stretch packaging having a three-layer structure was produced in the same manner as in Example 1 except that a resin composition consisting of 1.5 wt% of sorbitan oleate [Example 1] was used. The physical properties and practicality of this film are shown in Tables 1 and 2.

Example 3 Nylon used in Example 1 as the resin (A) for the intermediate layer
70% by weight of 12/6 copolymer and ethylene / methacrylate
Metal salt of acid copolymer [Density 0.95 g / cm ³, Melting point
87 ° C; Mitsui DuPont Polychemical Co., Ltd., trade name
"Himilan 1702"] Resin composition consisting of 30% by weight
Used in Example 1 as the surface layer resin (B).
Ethylene / vinyl acetate copolymer resin 98.0% by weight,
Ethylene / ethyl acrylate / maleic anhydride ternary
0.5% by weight of polymer resin and sorbitan oleate 1.
Example 1 was repeated except that the resin composition consisting of 5% by weight was used.
Similarly, a three-layer structure laminated resin film for stretch packaging
Manufactured. The physical properties and practicality of this film are shown in Table 1.
You

Example 4 As a resin (A) for the intermediate layer, nylon 12 [density 1.0
1 g / cm ³ , melting point 178 ° C .; manufactured by Daicel Hüls Ltd., trade name “Daiamide L1901”] was used as the resin (B) for the surface layer in the ethylene / vinyl acetate copolymer resin 95. 5% by weight, 3.0% by weight of ethylene / ethyl acrylate / maleic anhydride terpolymer resin used in Example 1 and diglycerin monooleate [manufactured by Riken Vitamin Co., Ltd., trade name "Rikemar DO
100 "] A laminated resin film for stretch packaging having a three-layer structure was produced in the same manner as in Example 1 except that the resin composition of 1.5% by weight was used. The physical properties and practicality of this film are shown in Tables 1 and 2.

Example 5 As a resin (A) for the intermediate layer, nylon 6/66 copolymer [density 1.13 g / cm ³ , melting point 192 ° C .; manufactured by Mitsubishi Kasei Co., Ltd., trade name “Novamid EN220-5C”
S ”] is 89.5% by weight of the ethylene / vinyl acetate copolymer resin used in Example 1 as the surface layer resin (B), and the ethylene / ethyl acrylate / maleic anhydride ternary copolymer used in Example 1 is used. The same procedure as in Example 1 was carried out except that a resin composition consisting of 9.0% by weight of a polymer resin and 1.5% by weight of diglycerin monooleate (trade name "Rikemar DO100" manufactured by Riken Vitamin Co., Ltd.) was used. A three-layer laminated resin film for stretch packaging was manufactured. The physical properties and practicality of this film are shown in Tables 1 and 2.

Comparative Example 1 As the surface layer resin (B), a resin composition comprising 98.5% by weight of the ethylene / vinyl acetate copolymer resin and 1.5% by weight of sorbitan oleate used in Example 1 was used. In the same manner as in Example 1 except for the above, a laminated resin film for stretch packaging having a three-layer structure was manufactured. The physical properties and practicality of this film are shown in Tables 1 and 2.

The physical properties and practicality of the film are as follows. Tensile Breaking Strength, Tensile Breaking Elongation JIS Z-1702 Tensile Elastic Modulus JIS K-7113 Interlaminar Peeling Strength A three-layer film with a width of 2 cm was peeled in advance into one layer and two layers, and this sample was pulled by a Shopper type tensile tester. Maximum load when peeled off at a speed of 500 mm / min. Water vapor permeability JIS Z-0208 Oxygen permeability, carbon dioxide permeability Mitsubishi Yuka Co., Ltd. method

Antifogging Property As shown in FIG. 1, after placing Shiitake mushroom 1 on a tray 3 made of impact-resistant polystyrene, stretch-wrapped on laminated film 2 to prevent the antifogging property of the film after 4 days. It was observed with the naked eye. ◯: The product has a good appearance with no fogging or water droplets attached to the inner surface of the film. Δ: Fogging or a small amount of water droplets is present on the inner surface of the film. Poor: The appearance of the product was poor due to noticeable cloudiness or water droplets on the inner surface of the film. Preservation property Mushroom packaging was carried out in the same manner as in the evaluation of antifogging property, and the freshness state of fresh mushrooms was visually observed. X: Freshness was good, but less than 5 days. Δ: Freshness was good, but 5 to 7 days. ◯: Freshness was good, but more than 7 days.

Extensibility The raw bamboo shoots are placed on trays made of expanded polystyrene, expanded polystyrene, and impact-resistant polystyrene, respectively, and wrapped by an automatic stretch wrapping machine, A-18X [trade name] manufactured by Fujikikai Co., Ltd., at that time. The stretched state of the film was visually observed. ◯: The film stretches almost uniformly. X: The film stretches unevenly. Occurrence of tearing The film was wrapped in the same manner as in the extensibility evaluation, and the presence or absence of tearing of the film at that time was visually observed. Occurrence of wrinkles Packaging was performed in the same manner as in the extensibility evaluation, and the presence or absence of wrinkles in the film at that time was visually observed.

Presence or absence of delamination In the packaging process using an automatic packaging machine, the presence or absence of delamination of the film was observed when the film was fed. ◯: Delamination does not occur. X: Delamination occurs and the film winds around a roll.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

EFFECT OF THE INVENTION A laminated resin film for stretch packaging having excellent heat resistance, appropriate water vapor permeability and gas permeability, and excellent interlaminar adhesive strength was obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a package in which mushrooms are packaged using a film.

[Explanation of symbols]

 1 Mushroom 2 Laminated film 3 Tray

Claims (3)

[Claims] 1. An ethylene / vinyl acetate copolymer (B ₁ ) having a vinyl acetate content of 5 to 40% by weight on one or both sides of a polyamide resin film (A) 80 to 99.5% by weight.
And (a) 66 to 98% by weight of ethylene, (b) lower alkyl ester of acrylic acid (wherein the carbon number of the alkyl group is 1 to
4) 1 to 30% by weight and (c) maleic anhydride 1 to 4
A laminated resin film obtained by laminating an ethylene resin film layer (B) containing 20 to 0.5% by weight of a terpolymer (B ₂ ) with 10% by weight. 2. The polyamide resin of the film substrate of the layer (A) is selected from a nylon 12/6 copolymer and a nylon 6/66 copolymer having a melting point of 182 to 196 ° C. measured by a differential scanning calorimeter. The laminated resin film according to claim 1, which is 3. The layer (B) contains an aliphatic alcohol fatty acid ester, which is an ester compound of an aliphatic alcohol having 1 to 12 carbon atoms and a fatty acid having 10 to 22 carbon atoms, in an amount of 0.5 to 10 parts by weight. % Contained.
The laminated resin film described.