JP3444976B2 - Laminated film - 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 at least three layers, heat-set after being stretched in the machine direction and / or transverse direction, and having tearability in at least one direction. More specifically, for example, as a packaging material comparable to an aluminum foil used as a sealing base material (base material) such as a press-through pack (PTP) in pharmaceutical packaging, it is easy to tear in the longitudinal direction and / or the lateral direction. To provide a laminated film having excellent gas barrier properties and transparency.

[0002]

2. Description of the Related Art Conventionally, as a packaging material having easy tearability in the longitudinal direction and / or the lateral direction, paper, aluminum foil, cellophane alone or a composite material of paper, cellophane etc. and aluminum foil, etc. Had been used. In particular, since aluminum foil has excellent tearability and gas barrier properties, it can be used alone or in combination with other materials, such as paper, cellophane, or laminated films, for example, as a sealing base for PTP. It is often used as a material (base material) and other packaging materials with easy tearing properties.

Further, as a packaging material having easy tearability in the longitudinal direction and / or the lateral direction, the above-mentioned aluminum,
In addition to paper, cellophane, etc., polypropylene resin, polyethylene resin, polyamide resin, ethylene / vinyl acetate copolymer saponification name, polyvinyl chloride resin, uniaxially stretched film made of polystyrene resin, etc. Laminated films composed of a film and other materials (for example, paper, cellophane, plastic film, etc.) and those obtained by subjecting them to cuts, perforations, notches, etc. by secondary processing are used.

However, the above-mentioned aluminum foil alone or a laminated film of the aluminum foil and paper, cellophane, plastic film (for example, low-density polyethylene-based film), etc. does not have transparency and cannot be packaged. There are drawbacks.

Further, the uniaxially stretched film having the cuts, perforations, notches, etc., alone or from the uniaxially stretched film and other materials (for example, paper, cellophane, aluminum foil, plastic film, etc.) Laminated film, etc., which splits in the direction of cuts, perforations, notches, etc., but in other directions (eg, the direction perpendicular to the above direction)
In most cases, it did not tear. In addition, those that have been cut, perforated, notched, etc. by secondary processing to impart tearability, the perforations, notches, etc. are easily cut during transportation, and those with perforations are gas barriers. It is not preferable as a wrapping material because it deteriorates the property. Furthermore,
Because of the secondary processing, the number of processes increases and it becomes expensive,
There was a problem that the use as a packaging material was restricted.

[0006]

In view of the above-mentioned circumstances, the present invention is particularly excellent in transparency and gas barrier property,
It is an object to provide a laminated film having easy tearability in the machine direction and / or the transverse direction. For the above-mentioned purpose, the present inventors focused on a film made of a polyester resin having excellent transparency, gas barrier properties, etc., and relatively tearing, and as a result of continuing diligent studies, finally arrived at the present invention. .

[0007]

The feature of the present invention lies in that an adhesive layer (C) in which a layer (A) made of a polyester resin and a layer (B) made of a thermoplastic polyolefin resin are made of an adhesive resin. ) Is laminated in at least three layers, and is stretched in the longitudinal direction and / or the transverse direction at a ratio of more than 1.0 and less than or equal to 8.0 and heat-fixed. It is to provide a laminated film having tearability.

The polyester resin according to the present invention is a polymer having an ester bond in the molecule obtained by condensation polymerization of a dicarboxylic acid component and a diol component.
Examples of the dicarboxylic acid include aliphatic dicarboxylic acid, aromatic dicarboxylic acid, and alicyclic dicarboxylic acid alone and one or more kinds of derivatives thereof, or a mixture thereof. Preferable examples include aliphatic glycols and alicyclic glycols alone and one or more derivatives thereof, or a mixture thereof.

Specifically, as the acid component, adipic acid,
2 to 20 carbon atoms such as sebacic acid and dodecanedicarboxylic acid
Of aliphatic dicarboxylic acid, terephthalic acid, isophthalic acid,
Examples thereof include aromatic dicarboxylic acids such as nafurenedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Specific diol components include aliphatic glycols such as ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and 1,10-cyclohexanediol. Examples thereof include alicyclic glycols.

Among the above-mentioned polyester resins according to the present invention, the melting point is 250 to 300 ° C. and the intrinsic viscosity (IV) is
Is preferably 0.3 to 1.0 because the tearability, transparency and gas barrier property are melted. At this time, if the melting point is less than 250 ° C., brittleness tends to occur, and if it exceeds 300 ° C., easy tearing property deteriorates, which is not preferable. Also, the intrinsic viscosity (IV)
Is less than 0.3, the film-forming property tends to deteriorate, and if the intrinsic viscosity (IV) exceeds 1.0, the easy tearing property is lowered, which is not preferable.

The reason why the film made of the heat-resusible polyolefin resin according to the present invention is laminated is to reinforce the strength of the easily tearable film of the present invention. Preferred examples include homopolymers of olefins, mutual copolymers, other copolymerizable monomers, for example, copolymers with other vinyl monomers and modified copolymers thereof. it can. Specifically, polyethylene of various densities ranging from low density to high density (including linear low density polyethylene and ultra low density polyethylene), polypropylene, polybutene, mutual copolymers of these, ethylene-vinyl acetate copolymer , Ethylene-acrylic acid copolymer, ionomer resin, modified polyolefin resin, and the like.

Examples of the modified polyolefin resin described above include homopolymers or mutual copolymers of the above-mentioned olefins such as maleic acid, fumaric acid, acrylic acid, and other appropriate unsaturated carboxylic acids or acid anhydrides thereof. Typical examples thereof include those obtained by copolymerizing, for example, graft polymerization of a substance, an ester, a metal salt or the like, or a derivative thereof. Such a modified polyolefin-based resin alone or other components, for example, a mixture with other polyolefin-based resin is also included in the modified polyolefin-based resin. Such a modified polyolefin resin can be suitably used as an adhesive resin that constitutes the adhesive layer according to the present invention.

Examples of the adhesive resin that constitutes the adhesive layer according to the present invention include ionomer resins, ethylene-ethyl acrylate resins, and ethylene-vinyl alcohol copolymers, in addition to the above modified polyolefin resins.
The layer is not particularly limited as long as it can bond the layer made of polyester resin and the layer made of polyolefin resin.

Among the above-mentioned thermoplastic polyolefin resins, particularly preferred are low density polyethylene, linear density polyethylene, ionomer resin, modified polyolefin resin, ethylene-vinyl acetate copolymer and the like. The above thermoplastic polyolefin resins may be used alone or in combination of two or more.

Polyester resin layer (A) according to the present invention
The thickness is preferably in the range of 8 to 25 μ, and when the thickness of the polyester resin layer (A) is less than 8 μ, it is difficult to impart good easy tearability in at least one direction, and when it exceeds 25 μ. It is difficult to tear in any direction, which is not preferable. The thickness of the thermoplastic polyolefin resin layer (B) may be a thickness that does not impair the easy tearability of the film made of the polyester resin, and generally 5 to 15 μm is preferable. When it is less than 5 μm, the polyester-based resin layer cannot be reinforced, and when it exceeds 15 μm, the easy tearability in one direction (longitudinal direction) is improved, but the easy tearability in the right angle direction (horizontal direction) tends to be significantly reduced. Absent. The thickness of the adhesive resin layer (C) may be such that the polyester resin layer (A) and the polyolefin resin layer (B) can be adhered to each other, and preferably 1 to 5 μm.

The laminated film according to the present invention may be formed into a tubular film by the inflation method or a flat film by the coextrusion T-die method using an appropriate apparatus such as coextrusion. There is no limit.

In order for the laminated film according to the present invention to be easily tearable in at least one direction, it should be stretched in the machine direction and / or the transverse direction at a ratio of more than 1.0 times and not more than 8.0 times. is necessary. The stretching method is preferably a sequential biaxial stretching method in which after the film is formed, the film is first stretched in the machine direction with a heating roll, and subsequently stretched in the transverse direction with a tenter method, but is not particularly limited. The stretching temperature is not particularly limited, but usually 80 to 15
The temperature may be 0 ° C., preferably about 85 to 140 ° C.

At this time, if the draw ratio is 1.0 times or less, there is a tendency that easy tearability cannot be imparted in at least one direction, and if it exceeds 8.0 times, the number of frequent film breaks increases and the productivity tends to decrease. Is not preferable.

Further, in order to impart easy tearability in at least one direction, it is indispensable to heat-set after stretching. As the heat setting conditions, it is preferable to heat set at 180 to 240 ° C., preferably 200 to 220 ° C. for 2 to 6 seconds while relaxing 2 to 3%. At this time, if the heat treatment temperature is less than 180 ° C., the easy tearing property tends to decrease, and if it exceeds 240 ° C., the film becomes hard and the easy tearing becomes difficult, which is not preferable.

The application of the present invention is, for example, in PTP packaging for packaging tablets, capsules and the like of pharmaceuticals and the like, tablets and capsule-like small articles are provided in PTP pockets (projections or depressions) formed by vacuum molding or the like. A preferable example is a sealing base material in which one dose (one or several pieces) is packaged and the upper or lower flange is sealed, but in addition to this, excellent transparency, gas barrier property, and easy tearing property are provided. It can be used for food packaging materials that require (easy opening) and various other applications, and there is no particular limitation.

[0022]

The present invention is a laminated film comprising a polyester resin and a thermoplastic polyolefin resin, wherein the laminated film has a thickness of 1.0 to 8.
It is easily tearable in at least one direction by being stretched at a specified draw ratio of 0 times and subsequently heat set.
In addition, it is possible to provide a laminated film of a polyester resin film and a polyolefin resin film, which have excellent transparency and gas barrier properties.

[0023]

EXAMPLES The present invention will now be described in detail based on examples. The present invention is not limited to the examples below. In addition, in the following examples of the present invention, the measurement of each inspection item was performed by the following methods. Tensile strength (kg /
cm ² ) and tensile elongation were measured and evaluated according to JIS-Z1702. Tear propagation strength (g) is JIS-P81
Measurement and evaluation were performed according to 16. Haze (%) is ASTM
It was measured and evaluated according to D-1003. The gas barrier property is the oxygen permeability (25 ° C.-100% RH atmosphere, MOKON OXTRAN 10 / manufactured by Modern Controls Co., Ltd.).
The value of (measured at 50 A) was measured and evaluated.

Example 1 As a polyester resin, 100 mol% of terephthalic acid
Dicarboxylic acid component and ethylene glycol 87 mol%
A pellet obtained by melt-kneading a resin having a melting point of 256 ° C. and an intrinsic viscosity (IV) of 0.78, which was obtained by condensation polymerization with a diol component composed of 13 mol% of diethylene glycol, was used.

A layer comprising pellets of the polyester resin obtained above (water content of 100 ppm or less), density 0.925 g / cm ³ , melt flow rate (MFR)
(190 ° C.) = 2.3 g / 10 min, linear low density polyethylene (LLDPE) B layer having a melting point of 113 ° C., density 0.90 g / cm ³ , melt flow rate (MFR)
(190 ° C.) = 4.4 g / 10 min, Vicat softening point = 59 ° C. Through the C layer made of pellets, A / C / B
So that the three layers are independent from each other and melt coextruded by using three extruders and a three-layer T die connected to these extruders, and then cooled by a chill roll having a surface temperature of 35 ° C. A laminated film was obtained. The obtained film was successively stretched by a biaxial stretching machine at a stretching temperature of 90 ° C. in the longitudinal direction 1.2 times, and then at a stretching temperature of 100 ° C. for 4.
The film was stretched in the transverse direction 0 times and further heat-treated at 210 ° C. for 3 seconds. The obtained laminated film having a three-layer structure is A / C /
The thickness of B was 12/2 / 6μ. Table 1 shows the tensile strength, tensile elongation, tear propagation strength, haze and oxygen gas barrier of the three-layer film.

Example 2 As a polyester resin, 2,6
A pellet obtained by melt-kneading a polyethylene naphthalate resin having a melting point of 270 ° C. and an intrinsic viscosity (IV) of 0.43, which was obtained by condensation polymerization of naphthalene dicarboxylate and diethylene glycol, was used. A layer made of pellets of the polyethylene naphthalate resin (water content of 100 ppm or less), density 0.91 g / cm ³ , melt flow rate (MFR) (190 ° C.) = 1.34 g / 1
B layer made of polypropylene having a Vicat softening point of 155 ° C. or lower at 0 min and a thermo-adhesive resin having a density of 0.90 g / cm ³ , a melt flow rate (MFR) (190 ° C.) and a Vicat softening point of 40 ° C. or less. A through C layer
/ C / B, the three layers are melt-coextruded using three independent extruders and a three-layer T die connected to these extruders, and then flattened by cooling with a chill roll with a surface temperature of 50 ° C. A layered three-layer laminated film was obtained. The film thus obtained was successively stretched by a biaxial stretching machine at a stretching temperature of 120 ° C. in the longitudinal direction of 1.2 times, and then at a stretching temperature of 135.
The film was stretched 5.0 times in the transverse direction at ℃ and further heat-treated at 215 ℃ for 3 seconds to obtain a thickness composition of A / C / B: 10/2/8.
A laminated film having a three-layer structure of μ was obtained. Table 1 shows the tensile strength, tensile strength, tear propagation strength, haze and oxygen gas barrier of the three-layer film.

[0027]

The laminated film of the present invention is a laminated film which is excellent in transparency, haze and gas barrier property and which is made of a polyester resin having easy tearability in at least one direction. It can be used not only as a base material for packaging but also for various purposes as an excellent easily tearable material in place of a sealing base material for packaging and other packaging materials that require easy opening.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI B29K 67:00 B29K 67:00 B29L 7:00 B29L 7:00 9:00 9:00

Claims (3)

(57) [Claims] 1. A layer (A) made of a polyester resin and a layer (B) made of a thermoplastic polyolefin resin are laminated in at least three layers via an adhesive layer (C) made of an adhesive resin, and Stretched in the machine direction and / or the transverse direction to more than 1.0 times and 8.0 times or less at a temperature of 200 to 220.
A laminated film characterized by being heat-fixed while relaxing the film by 2 to 3% at a temperature of 2 to 6 seconds, and having easy tearability in at least one direction. 2. A layer (A) made of a polyester resin and a layer (B) made of a thermoplastic polyolefin resin are laminated in at least three layers via an adhesive layer (C) made of an adhesive resin, and A film formed by stretching 1.0 times in the machine direction and / or the transverse direction to 8.0 times or less and heat-setting, and having a tear propagation strength in the transverse direction measured by JIS-P8116 of 22 to 30 g. Which has easy tearability in at least one direction. 3. A layer (A) made of a polyester-based resin and a layer (B) made of a thermoplastic polyolefin-based resin are laminated in three layers via an adhesive layer (C) made of an adhesive resin, and then longitudinally. Greater than 1.0 times in the direction and / or the lateral direction, 8.
Stretching to 0 times or less and then heat fixing while relaxing the film by 2 to 3% at a temperature of 200 to 220 ° C. for a time of 2 to 6 seconds and having easy tearability in at least one direction. Method for manufacturing laminated film.