JP2002172742A - Biaxially stretched laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide double-layered film improved in aroma retentivity. SOLUTION: A biaxially stretched laminated film consists of at least three layers, that is, an X-layer comprising a saponified ethylene/vinyl acetate copolymer, a Y-layer comprising an aliphatic polyamide and a Z-layer consisting of 20-80 mass % of a xylilene type polyamide and 20-80 mass % of an aliphatic polyamide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide-based laminated film, which has both the excellent pinhole resistance of a polyamide film and the excellent gas barrier property of an EVOH film, and further has an excellent fragrance retention property. The present invention relates to a polyamide-based laminated film suitable for packaging materials such as pharmaceuticals.

[0002]

2. Description of the Related Art A laminated film comprising a polyamide film and an EVOH film combines the excellent pinhole resistance, transparency, and dimensional stability of a polyamide film with the excellent gas barrier properties of an EVOH film, and is used for packaging foods and pharmaceuticals. Used as a material. However, while this laminated film has excellent oxygen barrier properties, its fragrance retention is not at a satisfactory level. When packaging a strong odorous substance such as dressing, soy sauce or miso as a content, it takes only a few days. However, there was a problem that the odor began to leak out, and the use was often restricted. In addition, this laminated film has a lower strength than a polyamide single-layer film, and has insufficient pinhole resistance against bending and impact at low temperatures, so that it may fall or be pierced from the outside or by the contents. In some cases, troubles such as leakage of contents may occur due to the generated pinholes, and the functional properties of the packaging material were not sufficiently satisfactory.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polyamide-based laminated film having a scent-retaining property, a gas barrier property and a pinhole resistance.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in a laminated film comprising an EVOH layer and an aliphatic polyamide layer, a layer comprising a xylylene-based polyamide and an aliphatic polyamide It has been found that a laminated film having excellent fragrance retention, gas barrier properties, and pinhole resistance can be provided by laminating, and the present invention has been completed. That is, the gist of the present invention is as follows.

(1) X layer made of saponified ethylene-vinyl acetate copolymer (EVOH), Y layer made of aliphatic polyamide, 20 to 80% by mass of xylylene polyamide and 20 to 80% by mass of aliphatic polyamide A biaxially stretched laminated film having at least three layers and having a Z layer. (2) The biaxially stretched laminated film according to (1), wherein the X layer contains 5 to 15% by mass of talc. (3) The biaxially stretched laminated film according to (1) or (2), wherein the layer configuration is Y / Z / X / Z / Y.

[0006]

Next, the present invention will be described in detail. In the present invention, the X layer is made of saponified ethylene-vinyl acetate copolymer (EVOH). EVOH having an ethylene component content of 25 to 35 mol% and a saponification degree of vinyl acetate of 96 mol% or more, and more preferably 99 mol% or more is preferable because of its excellent gas barrier properties and strength.
If the content of the ethylene component is less than 25 mol%, a gel is easily formed, and if it exceeds 35 mol%, the properties such as strength and gas barrier properties of the obtained film are undesirably reduced.

In the present invention, it is preferable to add talc to the EVOH of the X layer. Addition of talc improves scent retention, gas barrier properties and pinhole resistance.
The average particle size of talc is preferably less than 1.3 μm. As the particle size increases, the transparency of the film is impaired,
It can be a problem. The amount of talc added to EVOH is 5 to 15% by mass, preferably 7 to 13% by mass. 5
If the amount is less than 15% by mass, the effect of improving gas barrier properties and fragrance retention is small, and if it exceeds 15% by mass, the transparency of the film and the increase in fish eyes due to the secondary aggregation of talc are not preferred.

Further, an ethylene-vinyl acetate copolymer, an olefin-unsaturated carboxylic acid copolymer or a metal salt thereof may be added to the EVOH of the X layer for the purpose of further improving pinhole resistance. .

In the present invention, the aliphatic polyamide which is a component of the Y layer and the Z layer is a thermoplastic resin having an amide bond (--CONH--) in its molecule and capable of being melt-molded. ), Polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610), polyaminoundecamide (nylon 11), polylauramide (nylon 12), and copolymers and mixtures thereof And nylon 6 is particularly preferable.

The aliphatic polyamide of the Y layer includes talc, silica, and talc as long as the performance of the film is not impaired.
A lubricant such as alumina, magnesia, calcium carbonate, ethylene bisstearylamide, calcium stearate, and the like, a pigment, a heat stabilizer, an antioxidant, a weathering agent, a flame retardant, a plasticizer, and a release agent can also be blended.

In the present invention, as typical examples of the xylylene-based polyamide which is a component of the Z layer, polymethaxylylene adipamide, polymetaxylylene sebacamide,
Examples thereof include polymethaxylylenesperamide, polyparaxylyleneadipamide, and copolymers and mixtures thereof. Among them, polymethaxylyleneadipamide is preferable.

In the present invention, the Z layer comprises 20 to 80% by mass of a xylylene-based polyamide and 20 to 8% of an aliphatic polyamide.
It must be composed of 0% by mass. When the content of the xylylene-based polyamide is less than 20%, the effect of improving the fragrance retention of the obtained film is not sufficient.

The biaxially stretched laminated film of the present invention comprises an X layer,
It is necessary to be composed of at least three types of layers, that is, a Y layer and a Z layer, but the layer configuration may be changed according to the use and purpose.

[0014] A typical layer structure is a layer made of EVOH in order to avoid physical properties such as strength and gas barrier properties of the obtained laminated film, and to avoid troubles caused by film breakage and EVOH water absorption during film production. It is preferable that the layer is not an external surface layer, and a five-layer configuration of Y / Z / X / Z / Y is preferable.

In the present invention, as a method of forming an unstretched laminated film, several kinds of resins constituting each layer are melted in separate extruders, and superimposed on a multilayer structure in a feed block, and then, are stacked with a die. An extrusion method (mono-manifold type) or a multi-manifold method in which several types of molten resin are superimposed on a multilayer structure in a die and extruded can be used. The method is preferred. After co-extrusion from a die, the film is rapidly cooled on a cooling roll to obtain an unstretched laminated film.

The stretching method of the unstretched laminated film includes:
Flat type simultaneous biaxial stretching, flat type simultaneous biaxial stretching, tubular method, etc. can be used, but since the film thickness accuracy is good and the physical properties in the film width direction are uniform, the flat type simultaneous biaxial stretching method Is optimal.

In the flat simultaneous biaxial stretching method, the unstretched laminated film is subjected to a water-containing treatment in a temperature-controlled hot water tank.
The end of the film is gripped with a clip and the temperature is 80 to 200.
At a stretch ratio of about 2.5 to 4 times each at a temperature of 180 ° C. and a heat treatment at a temperature of 180 to 220 ° C. at a relaxation rate of 3 to 8% in the width direction of the film. An axially stretched laminated film can be obtained.

The thickness of the biaxially stretched laminated film of the present invention is not particularly limited, but when it is used as a flexible packaging material, the thickness is usually 10 to 50 μm. When the thickness is small, it is difficult to achieve both the pinhole resistance and the gas barrier properties / fragrance retention, and when the thickness is large, the transparency and the bending fatigue resistance deteriorate.

[0019]

Next, the present invention will be described more specifically with reference to examples. In addition, the raw materials used for the evaluation of the examples and the comparative examples and the measuring methods are as follows.

(1) Raw material poly-ε-capramide (nylon 6): manufactured by Unitika
A1030BRF Polymeta-xylene adipamide (MXD6): MX Nylon 6011 EVOH manufactured by Mitsubishi Gas Chemical Co., Ltd. EVOH: Eval EP-F101BZ manufactured by Kuraray Co., Ltd.
(Ethylene copolymerization ratio 32 mol%) Talc: Super Talc SG-200 manufactured by Nippon Talc
0

(2) Measurement method Scent-retaining property An adhesive / LLDPE (50 μl) was applied to the biaxially stretched laminated film.
m) is laminated, dressing is performed using the film, and a small bag filled with soy sauce (80 mm × 80 mm outer size bag)
Was made. Put the sachet in a 100 ml reagent bottle
It was stored in an atmosphere of 0 ° C. and 65% RH, and the presence or absence of odor leakage was checked by a sensory test every time. The evaluation criteria were as follows. ×: Confirmation of odor leakage after 10 days △: Confirmation of odor leakage after 20 days ○: No odor leakage after 20 days

Oxygen permeability Using OX-TRAN2 / 20 manufactured by Modern Control, at 20 ° C.
It was measured under the condition of 85% RH. (Unit: ml / (m ²
day ・ MPa) / (1 sheet thickness)

Bend pinhole resistance Met of Fed. Test Method Std. 101C shown in MIL-B-131F
According to hod 2017, a sample of 12 inches × 8 inches is gripped in a cylindrical shape having a diameter of 3.5 inches. 500 ° C under
The evaluation was made based on the number of pinholes after the bending.

After peeling off the end of the laminated film having a width of 15 mm at the interface,
The peeling strength was measured by a T-peel method at a peeling speed of 300 mm / min in an atmosphere of 0 ° C. and 65% RH using an autograph manufactured by Shimadzu Corporation.

Example 1 Talc was added at a ratio of 10% by mass to EVOH.
The mixture was melt-kneaded in a twin-screw extruder set at 210 ° C. and pelletized. 30% by mass of nylon 6 and 70% of MXD6
The mixture obtained by mass mixing was melt-kneaded with a twin-screw extruder set at 270 ° C. to obtain pellets. Next, using a co-extrusion T die for three types and five layers, nylon 6 is extruded from the first extruder at 250 ° C. (Y layer), and talc-containing EVOH pellets are extruded from the second extruder at a temperature of 215 ° C. (X layer),
A mixed pellet of nylon 6 and MXD6 is respectively extruded from the third extruder (Z layer), and a film laminated in the order of Y / Z / X / Z / Y with a multi-manifold type die is adjusted to a surface temperature of 18 ° C. Quenched by closely contacting it on the cooled cooling drum, and the thickness of each layer is Y / Z / X / Z / Y = 45/5.
An unstretched laminated film having a thickness of / 50/5/45 µm and a total thickness of 150 µm was obtained. The obtained unstretched laminated film is heated at 60 ° C.
After a water absorption treatment for 90 seconds, the film was simultaneously biaxially stretched to obtain a biaxially stretched laminated film having a thickness of 15 μm. The stretching conditions were 3 times in the vertical direction and 3.3 times in the horizontal direction at a temperature of 175 ° C.
10 ° C., relaxation rate 5%.

Example 2 Except that talc was not added to EVOH, extrusion and stretching were performed in the same manner as in Example 1 to obtain a biaxially stretched laminated film having a thickness of 15 μm.

Example 3 Extrusion and stretching were performed in the same manner as in Example 1 except that the mixing ratio of nylon 6 and MXD6 in the Z layer was changed.
A μm biaxially stretched laminated film was obtained.

Comparative Example 1 Extrusion, stretching, and thicknessing were performed in the same manner as in Example 2 except that the mixed pellets of nylon 6 and MXD6 were not charged into the third extruder, and only nylon 6 was charged instead. Fifteen
A μm biaxially stretched laminated film was obtained.

COMPARATIVE EXAMPLE 2 Extrusion and stretching were performed in the same manner as in Example 1 except that only MXD6 was used as the pellets to be fed into the third extruder.
A μm biaxially stretched laminated film was obtained.

Comparative Example 3 Nylon 6 and MXD6 in the pellets fed into the third extruder
Was extruded and stretched in the same manner as in Example 1 except that the mixing ratio was changed to obtain a biaxially stretched laminated film having a thickness of 15 μm.

[0031]

[Table 1]

As shown in Table 1, nylon 6 and MXD
The film provided with the intermediate layer mixed with No. 6 has improved fragrance retention, and hardly decreases the interlayer peeling strength. Further, by adding a specific amount of talc to the EVOH layer as in Example 1, the fragrance retention property is further improved, and the barrier performance and the pinhole resistance are also improved. On the other hand, in Comparative Example 1, since no intermediate layer containing MXD6 was provided, and talc was not contained in EVOH, the fragrance retention was low, and odor leakage occurred after only 10 days. Comparative Example 2 shows excellent fragrance retention, but the adhesion between Nylon 6 and MXD6 is poor, so that the delamination strength is remarkably reduced, which is insufficient for practical use. Comparative Example 3 is EV
The addition of talc to OH improves the fragrance retention, but the addition of MXD6 in the intermediate layer is low, and a sufficient fragrance retention improvement effect has not been obtained.

[0033]

As described above, according to the present invention, the polyamide film has excellent strength, dimensional stability and excellent gas barrier properties of EVOH, and is provided with a layer containing a xylylene-based polyamide to maintain the fragrance. A film with improved properties can be obtained. According to the present invention, a film having improved fragrance retention, gas barrier properties, and pinhole resistance without impairing the strength of the film or increasing the raw material cost by incorporating a predetermined amount of talc into the EVOH. Can be obtained, and the range of use of the gas-barrier laminated film, which has been restricted so far, greatly expands. Therefore, the industrial utility value of the laminated film produced according to the present invention is extremely high.

Continued on front page F-term (reference) 4F100 AC10C AC10E AK46C AK46E AK48B AK48C AK48D AK48E AK69A AL05C AL05E BA03 BA05 BA06 BA07 BA10A BA10C BA10E BA16 EJ38 GB23 JD02 JK14 JL00 YY00C YY00E

Claims (3)

[Claims] 1. An X layer composed of a saponified ethylene-vinyl acetate copolymer (EVOH), a Y layer composed of an aliphatic polyamide, and a Z composed of 20 to 80% by mass of a xylylene-based polyamide and 20 to 80% by mass of an aliphatic polyamide. Having layers,
A biaxially stretched laminated film comprising at least three layers. 2. The biaxially stretched laminated film according to claim 1, wherein the X layer contains 5 to 15% by mass of talc. 3. The biaxially stretched laminated film according to claim 1, wherein the layer constitution is Y / Z / X / Z / Y.