JPH04361038A - Composite film for packing - Google Patents

Abstract

PURPOSE:To prevent the release of the base material and intermediate layer composed of straight chain linear low density polyethylene of a composite film used in a packing bag even when said film is preserved over a long period of time and to develop the antistatic effect of the inner surface layer thereof over a long period of time. CONSTITUTION:A composite film is constituted by laminating and bonding a straight chain linear low density polyethylene layer 3 to the surface of a base material layer 1 through an anchor coat layer 2 and laminating and bonding an inner surface layer 4 composed of an ethylenic resin film containing 0.1-2wt.% of an antistatic agent to the surface of the straight chain linear low density polyethylene film layer 3, and the straight chain linear low density polyethylene film layer 3 being an intermediate layer, prevents the transfer of the antistatic agent.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a composite film used for packaging bonito flakes, bacon, ham, chikuwa, cookies, etc.

0002

[Prior Art] Low-density polyethylene, ethylene-vinyl acetate copolymer, which has a highly rigid resin film as a base material and contains 0.1 to 2% by weight of an antistatic agent on the surface of this base material layer.
Metal salt of ethylene/acrylic acid copolymer (Zn, Na)
Using a laminated film with ethylene resin films such as
It is known that it can be used as packaging bags for bacon, ham, fruits and vegetables (Japanese Patent Publication No. 60-34460, Japanese Patent Publication No. 3-23332, Japan Food Science 1).
(September 977 issue, Volume 16, Page 77).

[0003] As a base material, cellophane, stretched nylon film, biaxially stretched polypropylene film, polyethylene terephthalate film, aluminum foil, or biaxially stretched polypropylene film is used with an adhesive to form polyvinyl alcohol film or ethylene-vinyl alcohol copolymer film. [March 1973, Package Co., Ltd.] Special issue of Packaging published by Ningsha, pp. 212-215 and September 1977, Japan Food Science published by Nihon Shokuhin Publishing Co., Ltd., pp. 72-83].

[0004] Since the inner surface of the bag is an ethylene resin film layer (heat-sealable resin layer) containing an antistatic agent, scraps of shaved bonito flakes and cookies contained in the bag may adhere to the bag and cause an appearance. without damaging it. In addition, some antistatic agents have an antifogging effect, so the inside of the bag will not fog up even when fruits and vegetables are packaged.

[0005]

[Problems to be Solved by the Invention] Japanese Patent Publication No. 60-34460 discloses a method for maintaining the antistatic and antifogging effects of bags for a long period of time without increasing the amount of antistatic agent in the bag material. A polyolefin layer that does not contain a surfactant is interposed between the base film and an ethylene resin film (heat-sealable resin layer) that contains a surfactant (also has antistatic and antifogging effects). That is valid.

However, the resins for the intervening layer described in this publication are low-density, medium-density, and high-density polyethylenes, ethylene-vinyl acetate copolymers, ethylene-propylene copolymers, ionomers, and other ethylene-based resins. In the resin film, the antistatic agent migrates to this intervening layer over time, reducing the antistatic effect of the inner ethylene resin film and decreasing the adhesive strength of the anchor coating agent layer due to the migrated antistatic agent. It was found that the adhesive force between the base layer and the intervening layer of the ethylene resin film was reduced, causing inner layer peeling.

[0006] The present invention does not cause peeling of the inner layer between the base material layer and the ethylene resin film layer even when stored for a long period of time.
Another object of the present invention is to provide a packaging composite film that is suitable for forming bags that have an antistatic effect over a long period of time.

[0007]

[Means for Solving the Problems] The present inventors have discovered that the above problems can be solved by using linear polyethylene having a density of 0.88 to 0.940 g/cm3 as the ethylene resin. He has completed his invention. That is, in order to achieve the above object, the packaging composite film characterized by the present invention has a linear low-density polyethylene film layer laminated and bonded on the surface of a base material layer via an anchor coating agent layer. An inner layer made of an ethylene resin film containing 0.1 to 2% by weight of an antistatic agent is laminated and adhered to the surface of a low-density polyethylene film layer.

[0008]

[Function] The bag formed by the composite film of the present invention is
Since there is an ethylene resin film containing an antistatic agent on the inner surface, debris and crushed items from stored items will not adhere to the inner surface of the bag, and after opening the bag, all stored items will be removed without leaving any residue inside the bag. can be easily taken out. Furthermore, the presence of the linear low-density polyethylene film layer prevents the antistatic agent from migrating to the base layer, thereby eliminating inner layer peeling between the base layer and the linear low-density polyethylene film layer.

[0009]

[Example] An example of the present invention will be described with reference to FIG. 1. 1 is a base material layer, 2 is an anchor coating agent layer, and 3 is laminated on the surface of the base material layer 1 via the anchor coating agent layer 2. The bonded linear low-density polyethylene film layer 4 is an inner layer (heat-sealable resin layer) made of an ethylene resin film containing an antistatic agent laminated and bonded to the surface of the linear low-density polyethylene film layer 3. The individual constituent materials will be detailed below.

As the base material layer 1, the above-mentioned biaxially oriented polypropylene film (BOPP), a laminated film of a biaxially oriented polypropylene film and polyvinyl alcohol, a oriented nylon film, an aluminum vapor-deposited polypropylene film, and a silicon oxide vapor-deposited polyethylene terephthalate are used. etc. are used. This base material layer 1 may be transparent or opaque, but its selection depends on the contents to be stored. Further, the thickness of the base material layer 1 is 8 to 60 μm, preferably 12 μm.
~40 μm.

The base layer 1 provides the packaging material with stiffness and gas barrier properties depending on the material. Printing may be applied to the front or back side of the base layer 1, and an antistatic agent may also be applied to the surface, or a kneaded type antistatic agent may be mixed into the base layer 1. Sometimes it is done.

As the anchor coating agent layer 2, isocyanate, polyester/isocyanate, polyether/isocyanate, polyethyleneamine, organic titanate, or polybutadiene is used, and the coating amount is 0.01 to 1.0 g. /m2 (dry), preferably 0.05 to 0.58 g/m2 (dry).

Straight chain low density polyethylene film layer 3
is a copolymer of ethylene and α-olefin having 4 to 12 carbon atoms and has a density of 0.88 to 0.940 g/cm.
3 are used. This resin is obtained by copolymerizing ethylene and α-olefin in the presence of a chromium-based or Ziegler-based catalyst using a low-pressure gas phase method, liquid phase method, or solution method.
is 0.1 to 50g/10min. These are common. The α-olefin is butene-1
, pentene-1, hexene-1, heptene-1, octene-1, 1,4-methylpentene-1, etc. are used, and the thickness of this linear low density polyethylene film layer 3 is 8.
~40 μm, preferably 10 to 30 μm, and this layer prevents the antistatic agent of the ethylene resin film that is the inner layer 4 from migrating to the base layer 1 side.

The inner layer 4 contains an antistatic agent in an amount of 0.1 to 2% by weight.
It is formed from an ethylene resin film containing ethylene resin, and has a thickness of 2 to 50 μm, preferably 10 to 40 μm. As an antistatic agent, N,N-bis(2
-Hydroxyethyl)alkylamine, oleic acid monoglyceride, oleic acid diglyceride, stearic acid monoglyceride, stearic acid diglyceride, polyoxyethylene sorbitan fatty acid ester, polyoxyalkyl phenyl ether, polyethylene glycol fatty acid ester, etc. are nonionic antistatic agents. preferable.

Examples of the ethylene resin film include low density polyethylene, ethylene/vinyl acetate copolymer (vinyl acetate content: 1.5 to 18% by weight), Surlyn, ethylene/acrylic acid copolymer, etc. with a melting point of 80 to 80. A temperature of 135°C is preferred, but low density polyethylene, ethylene, etc.
Vinyl acetate copolymers are preferred because they are inexpensive and non-sticky. The inner layer 4 is used to heat-seal the inner layers together at a heat-sealing temperature of 100 to 200° C. when forming the bag.

The composite film of the present invention is prepared by coating the anchor coating agent 2 on the surface of the base layer 1, drying it, and then forming a linear low-density polyethylene film containing no antistatic agent and an antistatic agent. A co-extrusion method in which ethylene resin films are extruded together through a single die, or
Tandem lamination method uses two dies to laminate each resin, or film lamination method uses resin extruded from one die to bond a film coated with antistatic agent in advance. , is manufactured by adhering a linear low-density polyethylene film side to the base material layer 1 side, and its thickness is generally 30 to 100 μm. Then, this composite film can be made into a bag by heat-sealing the three side edges (three-sided bag and free-standing bag), or by folding it from the center and heat-sealing both ends to form a bag (gassho bag and gassho gusset bag). do.

Next, a specific example of implementing the present invention will be explained.

Example 1 An isocyanate adhesive was applied in an amount of 2.0 g/m2 (dry) on the printed side of a biaxially oriented polypropylene film (BOPP) with a thickness of 20 μm and whose surface was printed as the base layer 1. Then, on this adhesive layer, a biaxially stretched polyvinyl alcohol film (manufactured by Unitika Co., Ltd.) with a wall thickness of 12 μm is placed.
0.2 g/m2 (dry) of an isocyanate-based anchor coating agent was applied onto the biaxially stretched polyvinyl alcohol film of the base layer, and after drying, 0.5 g/m2 of sorbitan monooleate was applied. Ethylene/vinyl acetate (vinyl acetate content: 6% by weight) copolymer film containing ethylene/vinyl acetate (vinyl acetate content: 6% by weight) and linear low density polyethylene x704-1 (trade name: ethylene/butene) manufactured by Mitsubishi Yuka Co., Ltd. 1 copolymer; density 0.92 g/cm3) film is extruded with two dies (tandem lamination method), and after dry lamination, base material layer (34 μm) / anchor coating agent layer (0.2 μm) / straight chain linear Composite film of low density polyethylene film layer (20 μm)/ethylene/vinyl acetate copolymer film layer (30 μm) (total thickness 8
4.2 μm) was obtained.

Example 2 Ethylene 4-methylpentene manufactured by Mitsui Petrochemical Industries, Ltd. was used as a linear low-density polyethylene film.
A composite film was produced in the same manner as in Example 1 above, except that Copolymer 15100C (trade name) was used.

Example 3 The same procedure as in Example 1 was carried out except that ethylene-octene-1 copolymer 1018D (trade name) manufactured by Idemitsu Petrochemical Industries, Ltd. was used as the linear low-density polyethylene film. A composite film was produced.

Example 4 Instead of the antistatic agent-containing ethylene/vinyl acetate copolymer film, a film containing 0.3% by weight of N,N-bis(2-hydroxyethyl)alkylamine and having a density of 0.92 g
A composite film was produced in the same manner as in Example 1 above, except that low density polyethylene (LDPE) with a density of /cm3 was used.

Example 5 A composite film was produced in the same manner as in Example 1 except that a polyethylene terephthalate film (PET) having a wall thickness of 12 mm was used as the base layer.

Comparative Example 1 A composite film was produced in the same manner as in Example 1 above, except that a low-density polyethylene film having a density of 0.92 g/cm 3 was used in place of the linear low-density polyethylene film.

Evaluation Regarding the composite films shown in Table 1 manufactured in each of the above Examples and Comparative Examples, the surface side of the base layer and the inner layer containing the antistatic agent after one day had passed after manufacturing the composite film. The surface resistivity value of the composite film and that after 30 days of manufacture of the composite film were investigated. In addition, the antistatic agent-containing inner layer sides of this composite film were heated at 140°C and 2 kg/cm2.
, heat seal in 2 seconds to form a bag, JIS Z-
1526 for bag-making strength (width of heat-sealed part is 15 m)
Furthermore, in the same manner, the bag-making strength was measured after the bags were left at a temperature of 40° C. and a relative humidity of 90% for 90 days, and the results are shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

Effects of the Invention The composite film for packaging of the present invention has a multilayer structure consisting of a base layer, an anchor coating agent layer, a linear low-density polyethylene film layer (intermediate layer), and an inner layer consisting of an ethylene resin film containing antistatic. By adopting this, the linear low-density polyethylene film layer of the intermediate layer prevents the antistatic agent from migrating, so the antistatic effect of the inner layer can be maintained over a long period of time, and the base layer and intermediate layer This completely eliminates the conventional problem of peeling.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing one embodiment of the present invention.

[Explanation of symbols]

1 is the base material layer 2 is anchor coating agent layer 3 is a linear low density polyethylene film layer 4 is an inner layer

Claims (1)

[Claims] Claim 1: A linear low-density polyethylene film layer is laminated and adhered to the surface of the base material layer via an anchor coating agent layer, and an antistatic agent is applied to the surface of the linear low-density polyethylene film layer at a rate of 0.1. Composite film for packaging, characterized in that it is formed by laminating and adhering an inner layer made of an ethylene resin film containing ~2% by weight.