JP3197080B2 - Laminated film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film comprising ethylene resin / styrene-butadiene copolymer + ethylene resin / ethylene resin. The laminated film is excellent in transparency, impact resistance, piercing resistance, cold resistance, weather resistance, chemical resistance, workability, and excellent cross-cutting property with a weak force, and has a film waist, dimensions Excellent stability, control of gas permeability, moisture permeability, control of longitudinal shrinkage, and good heat sealing properties, so that tapes, adhesive tapes, masking films, masking tapes, temporary adhesive films, freshness preserving films , Plastic envelopes, easy-open packaging bags, automatic packaging films, shopping bags, standing bags, transparent packaging boxes, building materials, moisture-proof sheets, laminating films, agricultural films, food packaging materials, electronic component packaging materials, machine component packaging materials It is used as cereal packaging material, fish and shellfish packaging material, etc.

[0002]

2. Description of the Related Art Polystyrene films are used as various packaging materials because of their excellent transparency and dimensional stability and their rigidity. However, impact resistance, moisture resistance, chemical resistance, flexibility, Since there is a problem in heat sealability and the like, a multilayer film laminated with a polyethylene film having relatively excellent physical properties has been produced. However, since the two have different polarities, the interlayer adhesion is weak even as a laminated film by the co-extrusion method, it peels off, and it is not practical, so it was made into a laminated film using a specific anchor coat agent or adhesive. However, since a large amount of organic solvent is used for the anchor coating agent and the adhesive, the working environment is deteriorated and the cost is increased. In order to solve this problem, it has been proposed to use a styrene-butadiene copolymer instead of polystyrene (Japanese Patent Application Laid-Open No. 55-1).
No. 32243), the delamination strength is weak, and improvement is desired.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has excellent film forming processability, transparency, impact resistance, and film resistance of a film made of polyethylene resin. There are properties such as piercing property, heat resistance, cold resistance, weather resistance, chemical resistance, moisture resistance, flexibility, etc., and gas permeability, moisture permeability control of the film made of styrene-butadiene copolymer, and stiffness. Combine that with properties that are excellent in film handling, standing, dimensional stability, rigidity, etc., and propose a laminated film with excellent properties, and propose a method for producing such a film, and
It is an object of the invention to solve the problem of delamination of the film.

[0004]

The present inventors initially produced a two-layer film comprising a polyethylene resin and a styrene-butadiene copolymer, but the melt viscosity of the styrene-butadiene copolymer was extremely low. Low, inflation method does not stabilize bubbles and cannot produce high-quality film, and T-die casting method does not allow the styrene-butadiene-based copolymer layer to be easily rolled and cannot be cast at high speed. It was found to be inferior and not practical. To solve this, styrene-
When a butadiene-based copolymer was used as an intermediate layer and a polyethylene-based resin was used on both sides to form a film by an inflation method and a T-die casting method, it was found that a film could be formed and a laminated film was obtained. However, when this delamination strength was measured, it was very weak and impractical.Therefore, when experiments were conducted by blending various polymers in the intermediate layer, surprisingly, only when the same polymer was blended in both outer layers, The present inventors have found that the performance of the laminated film is good and the problem of delamination is solved, and the present invention has been completed.

That is, the present invention relates to (1) an intermediate layer comprising a resin composition of 100 parts by weight of a styrene-butadiene copolymer having a styrene content of 65 to 85% by weight and 15 to 30 parts by weight of an ethylene resin. And an outer layer made of an ethylene-based resin, wherein the thickness of the intermediate layer occupies 15 to 90% of the total thickness of the laminated film, and the thickness of the entire laminated film is 25 to 200 μm. And (2) a resin composition of 100 parts by weight of a styrene-butadiene copolymer having a styrene content of 65 to 85% by weight and 15 to 30 parts by weight of an ethylene-based resin. The method for producing a laminated film described above, wherein the intermediate layer and both outer layers made of an ethylene-based resin are co-extruded to produce the laminated film.

In the present invention, the styrene-butadiene copolymer refers to a copolymer of styrene and butadiene obtained by anionic polymerization, cationic polymerization, coordination polymerization, radical polymerization, solution polymerization, emulsion polymerization, or the like. Block copolymer or a polymer obtained by hydrogenating these block copolymers to eliminate unsaturated double bonds in the polymer chain, and it is necessary that the styrene content be 65 to 85% by weight. If the styrene content is less than 65% by weight, the film-forming properties of the film are deteriorated, and the film loses its stiffness, and the dimensional stability, rigidity, standing properties, easy tearability by hand, etc. are deteriorated, which is not desirable. 8 styrene content
If it is more than 5% by weight, the flexibility, interlayer adhesion, cold resistance, impact resistance and the like of the film deteriorate, which is not desirable. In the styrene-butadiene copolymer, a part of styrene is converted to α-methylstyrene, vinyltoluene, pt-
It may be substituted with butylstyrene or the like, or a part of butadiene may be substituted with isoprene, 1-3-pentadiene, 2,3-dimethyl-1,3-butadiene or the like. In the present invention, the styrene-butadiene copolymer to be used may be, for example, selected from those sold under the following trade names in the above numerical range and used. K-resin (manufactured by Philips), Styrolex (manufactured by Bashu), Clearen (manufactured by Denki Kagaku Kogyo) and the like.

In the present invention, the ethylene-based resin is defined as ethylene alone or ethylene and another α-olefin such as propylene, butene-1,4-methylpentene-
1, hexene-1, octene-1, nonene-1, decene-1, tetradecene-1, octadecene-1, and the like. Or other unsaturated group-containing monomers such as styrene, α-methylstyrene, p-methylstyrene, t-butylstyrene,
Allylbenzene, butadiene, isoprene, chloroprene, vinyl fluoride, vinyl chloride, vinyl bromide, vinylidene fluoride, vinylidene chloride, vinylidene bromide, ethylene tetrafluoride, ethylene trifluoride, chlorotrifluoroethylene, dichlorodifluoroethylene, Vinyl acetate, vinyl propionate, methyl acrylate, ethyl acrylate, butyl acrylate, octyl acrylate, stearyl acrylate, methyl methacrylate, octyl methacrylate, stearyl methacrylate, methacrylic acid, itaconic acid, methylene glutaric acid, anhydride Itaconic acid, methyl vinyl ketone, phenyl vinyl ketone, ethyl vinyl ketone, methyl isopropenyl ketone, methyl vinyl ether, ethyl vinyl ether, phenyl vinyl ether,
Vinyl thioether, acrylonitrile, acrylamide, acryldimethylamide, dimethylaminoethyl methacrylate, 2-hydroxyethyl acrylate, glycerin methacrylate, glycidyl acrylate, glycidyl methacrylate, allyl acrylate, allyl methacrylate, ethylene glycol diacrylate, divinyl ether, N -Vinylpyrrolidone, N-vinylimidazole, ethylmaleimide, N-vinylphthalimide, vinylpyridine, N-vinylcarbazole, N-vinyl-
N-methylacetamide, N, N-dimethylaminoethyl acrylate, t-butylacrylamide, methacrylamide, t-butylaminoethyl methacrylate, vinyl sulfide, trimethoxyvinylsilane, triethoxyvinylsilane, γ-methacrylopropyltrimethoxysilane, vinyltrichlor It is a resin obtained by copolymerizing silane, diphenylmethylvinylsilane and the like.

Typical examples are high-pressure polyethylene, linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer (EV)
A), ethylene-ethyl acrylate copolymer (EE
A), ionomers, ethylene-styrene copolymers and the like. However, ethylene resins having a density of 0.945 or more cannot be used in the present invention because they have poor transparency, adhesiveness, flexibility and the like.

In the present invention, ethylene-based resin 15 to 3 is added to 100 parts by weight of styrene-butadiene copolymer.
Although the resin composition containing 0 parts by weight is used as the intermediate layer, if the amount of the ethylene-based resin is less than 15 parts by weight, the adhesive strength between the intermediate layer and both side layers is insufficient, and both layers are easily peeled off. It is not desirable. On the other hand, if the amount is less than 15 parts by weight, the extrusion speed of the intermediate layer from the die becomes low, and the productivity of the laminated film is undesirably reduced. When the blending amount of the ethylene resin is more than 30 parts by weight, the cross-cutting property due to the weak force of the film, the stiffness of the film, dimensional stability, rigidity, gas permeability,
The moisture permeability deteriorates, which is not desirable.

The thickness of the laminated film of the present invention is 25 to 20.
0 μm, and less than 25 μm, the mechanical strength is insufficient, and the handling property of the film deteriorates, which is undesirable.
If it exceeds 200 μm, flexibility and handleability deteriorate, and economical efficiency is lost. The ratio of the intermediate layer to the laminated film is 15 to 90%,
If it is less than 15%, the crossing property due to the weak force of the film,
The film's stiffness, dimensional stability, rigidity, gas permeability, moisture permeability, etc. deteriorate, which is undesirable. If it exceeds 90%, coextrusion becomes impossible, and mechanical properties, cold resistance, friction resistance, economy,
Flexibility also deteriorates, which is not desirable. The thickness of each of the two outer layers may be the same or different, but it is important that each occupy at least 5% of the total thickness of the laminated film in order to enable co-extrusion.

The laminated film of the present invention can be produced by a coextrusion molding machine using each of the resin compositions to be the intermediate layer and both outer layers. In this case, for example, an inflation method using a circular die, a T-die method using a flat die Etc. are applicable.

[0012]

Next, the present invention will be described in more detail with reference to examples.

Example 1 Preparation of Raw Materials Intermediate layer: Styrene-butadiene copolymer (K-resin manufactured by Phillips) having a styrene content of 70% by weight and a butadiene content of 30% by weight (MI = 0.9 g / 10 minutes) 10
0 parts by weight, density 0.924g / ml made by gas phase method
MI = 0.9 g / 10 min ethylene-butene-1 copolymer (LLDPE, NUCG-5172 manufactured by Nippon Unicar)
A resin composition consisting of 20 parts by weight was prepared for the intermediate layer. Both outer layers: The above LLDPE was prepared for both outer layers. Production of Laminated Film The film was rapidly cooled by the following apparatus and conditions to produce an inflation film. -Extrusion device: blown film processing equipment manufactured by Placo Co., Ltd. (40 mm diameter x 3 units, L / D = 28)-Annular three-layer die: φ150 mm, die gap 1.5 m
m ・ Cooling device: with single lip straight and conical color ・ Discharge rate: 60 kg / hr ・ Die temperature: 190 ° C. ・ Blow ratio: 2.0 The thickness of the manufactured laminated film intermediate layer is 40 μm, each outer layer is 5 μm, total 50 μm
Laminated film. Evaluation haze degree of laminated film % 8.5 Gloss 60 ° 105 Tensile strength (kg / cm ² ) Length 319 Width 247 Elongation (%) Length 220 Width 540 Yield point strength (kg / cm ² ) Length 165 width 142 1% Sicant modulus (kg / cm ² ) Length 6,050 Width 4,200 Tear strength (kg / cm) Length 2.7 Width 10.3 Coefficient of friction 0.2 Heat seal strength (g / 15 mm, 150 ° C.) 1 , 100 delamination pear

Comparative Example 1 An experiment was conducted in the same manner as in Example 1, except that the styrene-butadiene copolymer having a styrene content of 60% by weight and a butadiene content of 40% by weight was used. The film-forming properties deteriorated, the film became loose, and the dimensional stability, rigidity, standing properties, and easy tear properties were poor.

Comparative Example 2 The same experiment as in Example 1 was carried out except that the styrene-butadiene copolymer having a styrene content of 90% by weight and a butadiene content of 10% by weight was used. Had poor flexibility, interlayer adhesion, cold resistance and impact resistance.

COMPARATIVE EXAMPLE 3 In Example 1, the styrene-butadiene copolymer 10
The same experiment as in Example 1 was performed except that 10 parts by weight of ethylene resin (LLDPE) was added to 0 part by weight. As a result, the adhesiveness between the intermediate layer and both outer layers was poor, and the layer was easily peeled off. . Further, the productivity of the film was poor.

Comparative Example 4 In Example 1, the styrene-butadiene copolymer 10
0 parts by weight of ethylene resin (LLDPE)
The same experiment as in Example 1 was carried out except that 5 parts by weight were blended. As a result, the cross-cutting property of the film, stiffness, dimensional stability, rigidity, gas permeability, moisture permeability and the like of the film were poor.

COMPARATIVE EXAMPLE 5 In Example 1, a laminated film having a thickness of 20 μm (intermediate layer 12 μm, each outer layer 4 μm) was prepared. However, the film was easily cut during processing. The target strength was weak, and the handleability was poor.

Comparative Example 6 In Example 1, the thickness was 100 μm (intermediate layer 92 μm,
Although a laminated film of each outer layer (4 μm) was produced, co-extrusion became difficult, and a film of constant quality could not be produced. The resulting film was not uniform in thickness, and had poor flexibility and cold resistance.

Comparative Example 7 In Example 1, a film having a thickness of 300 μm was produced, but the productivity of the film was poor, the blow-up ratio was not increased, and the transparency of the film was poor.

Example 2 Preparation of raw materials Intermediate layer: hydrogenated styrene-butadiene copolymer obtained by hydrogenating a styrene-butadiene copolymer having a styrene content of 85% by weight and a butadiene content of 15% by weight (K-resin manufactured by Philips) ) (MI = 5.0 g / 10 min) and ethylene-ethyl acrylate having a MI of 4.0 g / 10 min, a density of 0.930 g / ml and an ethyl acrylate content of 7 wt%, prepared by a high pressure method. A resin composition comprising 20 parts by weight of a polymer (NUC-6220 manufactured by Nippon Unicar) was prepared for the intermediate layer. Both outer layers: An ethylene homopolymer (DFD-0118 manufactured by Nippon Unicar) having a MI of 2.30 g / 10 min and a density of 0.923 g / ml prepared by a high pressure method was prepared for both outer layers. Production of laminated film Melt co-extrusion using three extruders having a diameter of 65 mm for the intermediate layer and 50 mm for each of the outer layers and a three-layer T-die connected thereto, an air chamber and a metal cooling roll having a surface temperature of 20 ° C To produce a T-die cast film.・ Discharge amount: 80 kg / hr ・ Die temperature: 230 ° C. The thickness of the produced laminated film intermediate layer is 50 μm, each outer layer is 25 μm, and the total is 100.
μm laminated film. Evaluation haze of laminated film % 7.5 Gloss 60 ° 110 Tensile strength (kg / cm ² ) Length 331 Width 210 Elongation (%) Length 185 Width 435 Yield point strength (kg / cm ² ) Length 183 Width 153 1% Sicant modulus (kg / cm ² ) Length 6,200 Width 5,900 Tear strength (kg / cm) Length 2.9 Width 11.5 Friction coefficient 0.3 Heat seal strength (g / 15 mm, 150 ° C.) 986 Delamination pear

[0022]

As described in detail above, the laminated film of the present invention has an intermediate layer composed of a specific styrene-butadiene copolymer and an ethylene resin, and the ethylene resin has both outer layers. It has excellent impact resistance, piercing resistance, cold resistance, heat resistance, weather resistance, chemical resistance, film stiffness, excellent handling, and weak cutting force, so it can be easily opened when used as packaging material. It has excellent dimensional stability, gas permeability and moisture permeability can be controlled, longitudinal shrinkage can be controlled, and heat sealability and heat seal strength are strong, so tapes, adhesive tapes, masking films, Masking tape, temporary adhesive film, freshness retaining film, plastic envelope, easy-open packaging bag, automatic packaging film, shopping bag, stand Ring back, transparent packaging boxes, building materials,
It is used as a moisture-proof sheet, laminating film, agricultural film, food packaging material, electronic component packaging material, mechanical component packaging material, grain packaging material, fish and shellfish packaging material, and the like. further,
Since the laminated film of the present invention uses a specific resin composition as an intermediate layer, it has a strong adhesive force with both outer layers, does not cause delamination, and has a specific resin layer as an intermediate layer and both outer layers. Therefore, co-extrusion became possible at a high image speed, and it became possible to provide a new type of laminated film of high quality.

Claims (2)

(57) [Claims] 1. An intermediate layer comprising a resin composition of 100 parts by weight of a styrene-butadiene copolymer having a styrene content of 65 to 85% by weight and 15 to 30 parts by weight of an ethylene resin, and an ethylene resin. A laminated film comprising both outer layers, wherein the thickness of the intermediate layer occupies 15 to 90% of the total thickness of the laminated film, and the thickness of the entire laminated film is 25 to 200 μm. Laminated film. 2. An intermediate layer comprising a resin composition of 100 parts by weight of a styrene-butadiene copolymer having a styrene content of 65 to 85% by weight and 15 to 30 parts by weight of an ethylene resin, and an ethylene resin. The method for producing a laminated film according to claim 1, wherein both outer layers are formed by co-extrusion.