JPH06134942A - Laminated body and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To obtain excellent gas barrier properties by laminating a biaxially oriented propylene homopolymer film, a propylene-alpha-olefin copolymer layer having special propylene content and melting point and surface-oxidized, an anchor coating agent layer and an ethylene-vinyl alcohol copolymer resin layer. CONSTITUTION:A laminate is obtained by laminating propylene-alpha-olefin copolymer having a propylene content of 68-99wt.% and a melting point of 115-155 deg.C on a surface of a biaxially oriented film base material layer of crystalline propylene homopolymer. A surface of the copolymer layer laminated on a surface of the homopolymer film is corona discharge treated, oxidized such as ozonized, etc., and the oxidized surface is covered with an anchor coating. The laminate is obtained by melting and laminating ethylene-vinyl alcohol copolymer resin film on a surface of the anchor coating agent layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to snack confectionery, rice confectionery,
The present invention relates to a laminated film having excellent gas barrier properties, which is useful as a packaging material for foods such as ham, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, packaging materials for snacks, rice crackers, hams, etc. have been required to have rigidity, transparency, water vapor barrier property, heat sealing property, gas barrier property and the like. , Or proposed. An ethylene / vinyl alcohol copolymer resin film (hereinafter sometimes abbreviated as EVOH) is attached to a biaxially oriented polypropylene film (OPP) with a polyurethane adhesive (1 to 5 g / m ² ) (so-called dry). Laminate), and then an isocyanate-based (urethane-based), polyethylene-based, polybutadiene-based,
An anchor coating agent such as titanate is coated, and low density polyethylene is melt-extrusion laminated on the coated surface, and then low density polyethylene or ethylene-vinyl acetate to which an antistatic agent is further added on the extrusion laminated surface of the low density polyethylene. A laminate obtained by melt extrusion laminating a copolymer resin (hereinafter referred to as EVA).

A coextrusion laminated film in which polypropylene, an olefin-based adhesive resin, EVOH, and a heat-sealable resin are co-extruded and laminated in the order of polypropylene / adhesive resin / EVOH / adhesive resin / heat-sealable resin (Japanese Unexamined Patent Publication 62-27172). A laminate obtained by extrusion-laminating a mixture of maleic anhydride-modified polypropylene and linear low-density polyethylene on a uniaxially longitudinally stretched propylene homopolymer film, and then extrusion-laminating an ethylene / vinyl alcohol copolymer sheet on the mixture sheet. A laminate obtained by stretching in the transverse direction (JP-A-63-205345).

However, the packaging material (1) has a large amount (1 to 5 g / m) of an adhesive dissolved in an organic solvent such as ethyl acetate for bonding the propylene homopolymer and EVOH.
There is a problem because it is used for ² ). In the packaging material, since the polypropylene of the base material is not stretched, it is necessary to increase the thickness of the polypropylene layer in order to increase the rigidity, and the transparency of the laminated body is reduced.

In the packaging material, since the ethylene / vinyl alcohol-based polymer resin layer is stretched and oriented, when the laminate is heat-sealed to form a bag, shrinkage easily occurs and the heat-sealing temperature range is narrow. . The present inventors
Surface is corona treated, the treated surface is further coated with the anchor coating agent described above, EVOH is extrusion-laminated on the coated surface, and then the EVOH surface is also subjected to anchor coating treatment in the same manner. When a laminate was extrusion-laminated at 0 ° C., the EVOH and the low-density polyethylene exhibited a practically sufficient adhesive strength, but the adhesive strength between the OPP and the EVOH was low and there was a practical problem. found.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to OPP.
A method for producing a laminated film having excellent gas barrier properties by extrusion laminating VOH, which comprises:
Provided is a method for producing a laminate film having excellent adhesive strength with and excellent gas barrier property.

[0007]

The first aspect of the present invention is to provide a crystalline propylene homopolymer biaxially stretched film substrate layer (1) having a propylene content of 68 to 99% by weight and a melting point of 115 to 155 ° C. In this order, the propylene-α-olefin copolymer layer (2), the anchor coat agent layer (3) and the ethylene-vinyl alcohol copolymer resin layer (4) obtained by oxidizing the surface of the propylene-α-olefin copolymer film of The present invention provides a laminate having a laminated structure.

The second aspect of the present invention comprises a crystalline propylene homocopolymer (1) and a propylene-α olefin copolymer (2) having a propylene content of 68 to 99% by weight and a melting point of 115 to 155 ° C. The propylene-α-olefin copolymer film (2) surface of the biaxially stretched product of the coextrusion film was subjected to an oxidation treatment, and then the oxidation treatment surface was subjected to an anchor coating agent, and then the surface of the anchor coating agent layer was treated with ethylene-vinyl alcohol. The present invention provides a method for producing a laminate, which comprises melt-laminating a copolymer resin film.

[0009]

The function is to oxidize the surface of the propylene-α-olefin copolymer layer treated with the anchor coating agent, and
By interposing between the PP and EVOH layers, OPP and E
The adhesive strength with VOH is improved.

[0010]

DETAILED DESCRIPTION OF THE INVENTION 1. Biaxially oriented propylene homopolymer film (OPP) The biaxially oriented propylene homopolymer film preferably has a melt flow rate of 0.5 to 10 g / 10 minutes and a density of 0.90 to 0.91 g / cm ³ , II. 90-100%
The propylene homopolymer film described above is biaxially stretched by a known stretching method such as simultaneous biaxial or sequential biaxial, and the thickness thereof is preferably about 5 to 150 μm.

2. Propylene-α olefin (excluding propylene) copolymer Propylene-α having a melting point of 115 to 155 ° C. laminated on the surface of the biaxially oriented polypropylene film (OPP).
The olefin copolymer is a differential thermal scanner; DSC manufactured by Perkin Elmer Co., Ltd., and a sample amount of 5.0 mg is used.
After being held at 190 ° C. for 3 minutes, crystallization was performed up to 50 ° C. at a temperature lowering speed of 10 ° C./minute, and when melting was performed at a temperature rising speed of 10 ° C./minute, the melting peak temperature of the higher temperature was 115. -The content of propylene at 155 ° C is 68-
It is a 99% by weight propylene-based copolymer.

Examples of the α-olefin include ethylene-butene-1, hexene-1 and the like, excluding propylene. The melt flow rate (hereinafter referred to as MFR) of the propylene-α olefin copolymer of the present invention is preferably 1 to 30 g / 10 minutes, particularly preferably 3 to 10 g /.
10 minutes, a highly crystalline or low crystalline copolymer,
Also included are mixtures of these.

OPP and propylene-α in the present invention
One or both of the olefin copolymers may be provided with an antioxidant, specifically 2,2'-methylene-bis-, for example.
(4-methyl-6-t-butylphenol), 4,4 '
-Butylidene-bis- (3-methyl-6-t-butylphenol), 4,4'-thiobis- (3-methyl-6-
t-butylphenol), tetrakis- [methylene-3
-(3,5-di-t-butyl-4-hydroxyphenol) prochionate] methane, 1,1,3-tris-
(2-Methyl-4-hydroxy-5-t-butylphenol) butane, 1,3,5-trimethyl-2,4,6-
Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene or the like is 0.0 based on 100 parts by weight of the resin.
It is preferable to add 3 to 0.2 parts by weight, and the biaxially oriented polypropylene film has an average particle size of 0.5 to 3
An anti-blocking agent having an average particle size of 3 to 8 μm, for example, silicon dioxide, zeolite, calcium carbonate, etc., is added to the propylene-α-olefin copolymer layer having a thickness of 0.1 to 0.4 with respect to 100 parts by weight of the resin. It is preferably added by weight. In addition, the biaxially stretched polypropylene film and the propylene-α-olefin copolymer layer have an antistatic agent, a lubricant, a nucleating agent, a pigment, which are usually used for polyolefin resins, to the extent that the adhesive strength with EVOH is not significantly reduced. Additives such as ultraviolet ray inhibitors, resins such as polyethylene, ethylene-based copolymers, holybten-1 and the like, and rubber and the like can be added.

The thickness of this propylene-based copolymer is 0.5.
Is about 20 μm. In the present invention, propylene-laminated on the surface of the biaxially oriented polypropylene film
The surface of the α-olefin copolymer layer is subjected to oxidation treatment such as corona discharge treatment and ozone treatment. The corona discharge treatment is carried out by using a known corona discharge treatment device such as a vacuum tube system or a thyristor system, and is set to about 36 to 50 dynes / cm, preferably 38 to 45 dynes / cm.
In the ozone treatment, an ozone gas generator is used, and ozone gas or a mixed gas of ozone and air or another gas, preferably a mixed gas of air having an ozone concentration of ³ to 50 g / m ³ , is used as propylene-α. The molten surface of the olefin copolymer is sprayed.

3. Anchor coat agent In the present invention, an anchor coat (primer coat) is applied to the corona discharge treated surface. As the anchor coat, known anchor coat agents such as isocyanate type, polyurethane type, polyester type, polyethyleneimine type, polybutadiene type, polyolefin type and alkyl titanate type can be used. Isocyanate compounds, polyurethanes, urethane prepolymers or mixtures and reaction products thereof, mixtures of polyesters or polyols or polyethers with isocyanates and reaction products, or solutions thereof are preferred anchor coating agents. These anchor coating agents are usually 0.0
1 to 0.5 g / m ² (dry solid content), preferably 0.1
~ 0.3 g / m ² coated.

4. Ethylene-vinyl alcohol copolymer resin The ethylene-vinyl alcohol copolymer in the present invention is a saponified product of ethylene-vinyl acetate copolymer,
The ethylene content is preferably 15 to 50 mol%, the saponification degree is 90% or more, the melt flow rate is 0.1 to 100 g / 10 min, and the ethylene content is 25 to 45 mol% from the viewpoint of gas barrier property and extrusion laminating processability. , Saponification degree 95%
As described above, the melt flow rate is more preferably 1 to 30 g / 10 minutes. To the ethylene-vinyl alcohol copolymer, the above-mentioned additives, resins, rubbers and the like should be added to such an extent that the adhesiveness with the propylene-α-olefin copolymer layer and the gas barrier property are not significantly reduced. You can

The extrusion laminate of the ethylene-vinyl alcohol copolymer in the present invention is a known single-type or tandem-type extrusion laminate, or a co-extrusion laminate or the like in which the ethylene-vinyl alcohol copolymer is used alone, or other It is made by extrusion lamination such as coextrusion lamination with adhesive resin and polyolefin resin. The above-mentioned coextrusion laminating is a preferable method because the heat seal layer can be extruded and laminated at the same time.

The wall thickness is 0.5 to 30 μm, preferably 1 to
Used at 20 μm. As such an adhesive resin, a modified resin obtained by graft-reacting an unsaturated carboxylic acid such as maleic anhydride, acrylic acid or itaconic acid or a derivative thereof with 0.01 to 10% by weight of a polyolefin resin.

An ethylene-α, β-unsaturated carboxylic acid ester random copolymer having an α, β-unsaturated carboxylic acid ester content of 10 to 35% by weight. An ethylene-vinyl ester copolymer resin containing 10 to 45% by weight of vinyl ester. Etc.

As the polyolefin resin used in the above graft reaction, low density polyethylene, high density polyethylene, ethylene-α olefin copolymer, ethylene-
α, β-unsaturated carboxylic acid copolymer or metal salt thereof (Li ⁺ , Zn ⁺⁺ ), polypropylene, propylene-α
Examples thereof include olefin copolymers and mixtures thereof. The thickness of the adhesive resin is preferably 5 to 100 μm, more preferably 10 to 80 μm.

5. Method for Producing Laminate The laminate of the present invention comprises a crystalline propylene homocopolymer (1) and a propylene-α-olefin copolymer (2) having a propylene content of 68 to 99% by weight and a melting point of 115 to 155 ° C. ) Propylene of biaxially stretched coextruded film
The surface of the α-olefin copolymer film (2) is oxidized,
Then, after applying an anchor coating agent to the oxidation-treated surface,
It is manufactured by melt-laminating an ethylene-vinyl alcohol copolymer resin film on the surface of the anchor coat agent layer. At this time, ethylene-vinyl alcohol (EV
OH) When melt-laminating the copolymer film, as described above, the adhesive resin, the polyolefin resin and the EVOH are used.
May be coextruded to improve the heat sealability of the laminate.

6. Laminated body The laminated body of the present invention has a wall thickness of 6 to 200 μm, an oxygen permeability of 0.5 to 20 cc / m ² · 24 hrs · atm, a water vapor permeability of 1 to 20 g / m ² · 24 hrs, and a haze of 30% or less. Are preferred. Furthermore, for the purpose of improving rigidity, tear resistance and gas barrier property, the OPP surface of this laminate is subjected to a known lamination method (extrusion laminating, sand extrusion laminating, coextrusion laminating, dry laminating, etc.) for polyester, polyamide, Aluminum foil, paper, cloth, non-woven fabric and the like can be further laminated.

[0023]

【Example】

Example 1 As an antioxidant, tetrakis- [methylene-3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate] 0.1 part by weight of methane and 0.15 part of silicon dioxide having an average particle size of 1 μm as an antiblocking agent.
Propylene homopolymer added (part by weight) (melt flow rate 2 g / min), 0.1 part by weight of the same antioxidant as above, and 3 μm of average particle size as anti-blocking agent.
Propylene-ethylene random copolymer (MFR 6 g / 10) having an ethylene content of 3.0% by weight and a melting peak temperature of 144 ° C. to which 0.15 parts by weight of silicon dioxide of m was added.
Min) and are fed to separate extruders, and melt-extruded into a sheet at 240 ° C. using a two-layer coextrusion T-die, and a surface temperature of
A two-layer laminated sheet was formed by cooling and solidifying with a 0 ° C. cooling roll.

This two-layer laminated sheet was stretched 5 times in the longitudinal direction at 115 ° C., further stretched 10 times in the transverse direction in a tenter oven at 168 ° C., and then heat-set at 150 ° C. to give ethylene on one surface. A bilayer stretched polypropylene film (thickness: 22 μm) was formed by laminating a propylene-ethylene random copolymer layer (thickness: 2 μm) having a content of 3.0% by weight (melting peak temperature: 144 ° C.).

The ethylene content of this bilayer laminated biaxially oriented polypropylene film was 3.0% by weight (melting peak temperature
(144 ° C.) propylene-ethylene random copolymer layer was subjected to corona discharge treatment so as to have a rate of 40 dynes / cm, and then the co-extrusion laminator equipped with three extruders with caliber of 90 mm, 65 mm, and 40 mm was used. Polyurethane anchor coating agent (made by Nippon Soda Co., Ltd.) on the discharge treated surface
Titabond T120; mixed solution of 7% by weight of polyisocyanate / polyether polyol, 0.6% by weight of curing agent and 92.4% by weight of ethyl acetate) is applied by a roll coating method, and then ethyl acetate is dried by a drier, The removed anchor coat agent layer was formed.

Next, an ethylene-vinyl alcohol copolymer resin [F-10, Kuraray Co., Ltd.] was added to the extruder having a diameter of 65 mm.
4 (trade name) ethylene content 32 mol%, saponification rate 99.
6%, MFR 4.4 g / 10 min], and a modified low-density polyethylene adhesive resin (MFR 4 g / 10
Min] is supplied to a 90 mm extruder, and low density polyethylene [LS31 (trade name) manufactured by Mitsubishi Yuka; density 0.919 g
/ Cm ³ , MFR 9 g / 10 min], and a feed block type co-extrusion device is used to co-align the ethylene-vinyl alcohol copolymer resin, the modified low-density polyethylene adhesive resin, and the low-density polyethylene in the order. It was extruded and co-extrusion laminated so that the ethylene-vinyl alcohol copolymer resin faced the surface of the anchor coat agent layer. The molding conditions for the coextrusion laminate are that the resin temperature is 230 ° C. and the coextrusion laminate thickness is ethylene-
Vinyl alcohol copolymer resin 3μm, modified polyethylene adhesive resin 3μm, low density polyethylene 30μm
And the coextrusion laminating speed was 80 m / min. Table 1 shows the evaluation results of the physical properties of the laminated film.

Examples-2 to 6 Laminated films were prepared in the same manner as in Example-1, except that the propylene-ethylene random copolymer of Example-1 was changed as shown in Table 1. Table 1 shows the evaluation results of the physical properties of the laminated film.
Shown in.

Example-7 The ethylene content of the bilayer laminated biaxially oriented polypropylene film in Example-1 was 3.0% by weight and the melting peak temperature was 1.
A propylene-ethylene random copolymer layer at 44 ° C,
Example 1 was repeated in the same manner as in Example 1 up to the point where corona discharge treatment was performed to 40 dyne / cm, and a single type extrusion laminator equipped with an extruder having a diameter of 90 mm was used for the above corona-treated surface. An anchor coat agent treatment was performed in the same manner as in No. 1. Next, an ethylene-vinyl alcohol copolymer resin [Kuraray Co. E-
105 (trade name), ethylene content 42 mol%, saponification rate 99.6%, melt flow rate 5.5 g / 10 minutes], resin temperature 240 ° C., extrusion laminating speed 60 m
Extrusion laminated with a thickness of 20 μm / min. Table 2 shows the evaluation results of the physical properties of the laminated film.

Comparative Example-1 A biaxially stretched film of propylene homopolymer (OP) was prepared without laminating the propylene-ethylene random copolymer layer of the bilayer laminated biaxially stretched polypropylene film in Example-1.
Example 1 was repeated except that only P) was used. Table 1 shows the evaluation results of the physical properties of the laminated film.

COMPARATIVE EXAMPLE-2 An example except that only the propylene homopolymer film (OPP) was used without laminating the propylene-ethylene random copolymer layer of the bilayer laminated biaxially oriented polypropylene film in Example-7. Same as -7. Table 2 shows the evaluation results of the physical properties of the laminated film.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Effect] Since the laminate of the present invention is provided with the specific propylene-α-olefin copolymer layer previously laminated on the surface of the biaxially oriented polypropylene film, ethylene-
Excellent adhesion with vinyl alcohol copolymer,
A laminated body having excellent heat seal strength and gas barrier property is obtained.

Claims (2)

[Claims] 1. A biaxially stretched film base material layer (1) of a crystalline propylene homopolymer, having a propylene content of 68 to 99.
Wt%, propylene-α-olefin copolymer layer (2) obtained by oxidizing the surface of a propylene-α-olefin copolymer film having a melting point of 115 to 155 ° C., an anchor coating agent layer (3), and ethylene-vinyl alcohol copolymer A laminate having a structure in which the resin layers (4) are laminated in this order. 2. A crystalline propylene homocopolymer (1)
And a propylene content of 68 to 99% by weight and a melting point of 11
Propylene-α of biaxially stretched product of coextruded film of propylene-α olefin copolymer (2) at 5 to 155 ° C.
The olefin copolymer film (2) surface is subjected to an oxidation treatment, and then the oxidation treatment surface is subjected to an anchor coating agent, and then the ethylene-vinyl alcohol copolymer resin film is melt-laminated on the anchor coating agent layer surface. A method for manufacturing a laminated body.