JPH07125149A - Easily tearable laminated film and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain, in addition to excellent easily tearable properties and linear cutting properties, high gas barrier properties. CONSTITUTION:The easily tearable laminated film comprises an easily tearable film which contains 40-85 pts.wt. of nylon 6 (Ny6) and 15-60 pts.wt. of methaxylylene adipamide (MXD6) (where Ny6+MXD6=100 pts.wt.) and has an elongation magnification of 2.8 times or more in an MD direction (film moving direction) and a TD direction (lateral direction of the film), and saponified ethylene-vinyl) acetate copolymer (EVOH) film laminated on one side surface of the easily tearable film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily tearable laminated film and a method for producing the same, which can be used in the fields of foods, chemicals, industrial products and the like.

[0002]

BACKGROUND ART In recent years, as a packaging material for foods, medicines and the like, a sealing base film such as linear low density polyethylene (L-LDPE) and a biaxial resin coated with vinylidene chloride resin. Stretched nylon (KONy)
A laminated film obtained by laminating a barrier film such as the above is used. This L-LDPE film is
Although it is safe because it has excellent seal strength, it has a large tear resistance and cannot be cut straight when used, and there is a problem with unsealability.

Conventionally, various proposals have been made for imparting a linear cut property (easy opening property) at the time of opening a packaging material. For example, (a) a laminated film having a uniaxially stretched film as an intermediate layer, (b) a structure that makes it easy to open by making fine scratches on the surface of the front substrate film, (c) opening in the opening part of the film For example, the configuration is such that a tape for use is attached. However, in each case, the easy-open property and the impact strength were insufficient, and the economy was poor.

Particularly in the fields of foods and medicines, the linear cut property for facilitating the opening and improving the appearance of the opening and the gas barrier property for long-term storage are required as important characteristics. On the other hand, the applicant has proposed an easily tearable film containing nylon 6 and metaxylylene adipamide (MXD6) in Japanese Patent Application Nos. 3-308427 and 4-253116.

This easily tearable film has provided excellent easy tearability, straight line cutability, and tentative gas barrier property, but it is limited to the field where higher gas barrier property is required. was there. Therefore, an object of the present invention is to provide an easily tearable laminated film which can obtain high gas barrier property in addition to excellent easy tearability and linear cuttability, and a manufacturing method thereof.

[0006]

The easily tearable laminated film according to the present invention is made of nylon 6 (Ny6).
~ 85 parts by weight and metaxylylene adipamide (MXD6)
15-60 parts by weight (however, Ny6 + MXD6 = 100
(Parts by weight), MD direction (the moving direction of the film) and TD direction (the width direction of the film), and the easily tearable film having a draw ratio of 2.8 times or more, and ethylene laminated on one side of the easily tearable film. -Saponified vinyl acetate copolymer (E
VOH) film.

In addition, the method for producing the easily tearable laminated film is 40 to 85 parts by weight of Ny6 and 15 to 60 of MXD6.
Original film containing parts by weight (however, Ny6 + MXD6
(= 100 parts by weight) in both MD and TD at a draw ratio of 2.8 times or more to prepare an easily tearable film, and then an EVOH film is extruded and laminated on one side of the easily tearable film. The chemical formula of MXD6 is shown in Chemical Formula 1 below.

[0008]

[Chemical 1]

The Ny6 is 40 to 85 parts by weight, preferably 50 to 80 parts by weight. Also, the MXD6 has 15
-60 parts by weight, preferably 20-50 parts by weight.
When MXD6 is less than 15 parts by weight, the easy tearing property and the straight line cutting property are deteriorated. When MXD6 is more than 60 parts by weight, the impact strength is significantly reduced and the practicality becomes poor. The stretch ratio of the easily tearable film is 2.8 times or more in both MD and TD, but is preferably
3.0 times or more. When the draw ratio is less than 2.8 times, the easy tearing property and the linear cutting property are deteriorated, and the impact strength is lowered, which causes a problem in practical use. Such a stretched film can be obtained by performing simultaneous biaxial stretching by, for example, a tubular method.

The EVOH has an ethylene content of 25 to 45.
It is suitable that the content is mol%, preferably 29 to 38 mol%. When the ethylene content is less than 25 mol%, burning or gel is likely to occur during extrusion, and when it exceeds 45 mol%, the gas barrier performance is deteriorated.
When an EVOH film is extruded and laminated on one surface of the easily tearable film, an adhesive for adhering both films is applied to at least one of them. In addition, necessary additives can be appropriately added to each of the films. Examples of such additives include anti-blocking agents (inorganic fillers, etc.), water repellents (ethylene bisstearate, etc.), and lubricants (calcium stearate, etc.).

[0011]

Example 1 Nylon 6 (Ny6) and metaxylylene adipamide (MXD6) were mixed at a ratio of 60 parts by weight and 40 parts by weight, respectively, and melt-kneaded in an extruder at 270 ° C., The melt was extruded from a die having a diameter of 90 mm as a cylindrical film and then rapidly cooled with water to prepare a raw film.
The Ny6 used was Nylon 6 [UBE Nylon 1023 FD (trade name), relative viscosity η _r = 3.6] manufactured by Ube Industries, Ltd., and the one used as MXD6 was manufactured by Mitsubishi Gas Chemical Co., Inc. Metaxylylene adipamide [MX nylon 6007 (trade name), relative viscosity η _r = 2.7]
Is.

Next, the obtained tube-shaped raw material is inserted between a pair of nip rolls, heated by a heater while injecting gas into the nip rolls, and air is blown from an air ring at the stretching start point to expand into bubbles. Then, simultaneous biaxial stretching in the MD direction and the TD direction by the tubular method was performed by taking them out with a pair of downstream nip rolls. The draw ratio during this stretching was 3.0 times in both MD and TD. Next, this stretched film was placed in a tenter type heat treatment furnace and heat-set at 210 ° C. to obtain an easily tearable film.

Next, a film obtained by coextruding a saponified product of ethylene-vinyl acetate copolymer (EVOH) and an adhesive was extruded and laminated on one surface of the easily tearable film according to this embodiment. A film was produced. The thickness of each layer of the easily tearable laminated film is 15 μm for the easily tearable film, 5 μm for the adhesive layer, and 5 μm for the EVOH film. The EVOH used was Eval resin (trade name, ethylene content 32 mol%) manufactured by Kuraray Co., Ltd.
The adhesive is Admer resin (trade name) manufactured by Mitsui Petrochemical Industry Co., Ltd.

Regarding this easily tearable laminated film,
The easy tearing property and the straight line cutting property were evaluated. The results are shown in Table 1 below. As for the easy tearability, the Emendorf tear strength value E is ○ when E ≦ 7 kg / cm 2 and 7 kg / cm <E <
9 kg / cm 2 was evaluated as Δ and E ≧ 9 kg / cm 2 was evaluated as x. When E is 9 kg / cm or more, the easiness of tearing is remarkably reduced, and especially the linear cut property is rapidly reduced.

The linear cuttability was evaluated as follows. The film having a width of 20 cm is cut at predetermined intervals W _s , for example, at intervals of 2 cm, the film is torn along these cuts, and the width W _e of the other end of the film piece is measured to obtain the original distance W _s . The deviation α is calculated as follows. α = [(W _s −W _e ) / W _s ] × 100 This measurement was performed on 10 pieces of film, and if the average value α (%) was less than ± 10% ◎ (linear cutability Is very good), ± 10% ≤ α ≤ ± 30% is evaluated as ○ (good linear cutting property), and α (%) exceeding ± 30% is evaluated as × (poor linear cutting property). . α (%) is ± 30%
If it exceeds, it becomes difficult to cut the film straight.

Further, the oxygen permeability was measured as an index of the gas barrier property of the packaging material. This measurement is based on ASTM-D-398
According to 5, it was carried out under the conditions of 23 ° C. and 0% RH. The results are shown in Table 1 below. In the column of comprehensive evaluation in Table 1, ⊚ indicates very good, ∘ indicates good, and x indicates poor.

Examples 2 to 5 Production similar to that of Example 1 except that the raw material composition and stretch ratio of the easily tearable film and the ethylene content and thickness of the EVOH layer in Example 1 were changed as shown in Table 1. By the process, easily tearable laminated films according to Examples 2 to 5 were obtained. For the easily tearable laminated film according to each example, the easily tearable property and the linear cut property were evaluated and the oxygen permeability was measured in the same manner as in Example 1. The results are shown in Table 1.

Comparative Examples 1 to 5 Production similar to that of Example 1 except that the raw material composition and stretch ratio of the easily tearable film and the ethylene content and thickness of the EVOH layer in Example 1 were changed as shown in Table 1. Laminate films according to Comparative Examples 1 to 5 were obtained by the process. With respect to the laminated film according to each comparative example, the easy tearing property and the linear cuttability were evaluated and the oxygen permeability was measured in the same manner as in Example 1. The results are shown in Table 1.

[0019]

[Table 1]

From Table 1, the easily tearable laminated films according to Examples 1 to 5 contained 60 to 80 parts by weight of Ny6 and MXD.
20 to 40 parts by weight of 6 and having an easily tearable film having a draw ratio of 3.0 times in the MD and TD directions, and an EVOH film laminated on one side of the easily tearable film. Therefore, it is understood that the film has excellent easy tearing property, and the linear cut property is also good or very good. Further, the oxygen permeability is very small and the gas barrier property is excellent.

On the other hand, the laminated films according to Comparative Examples 1 and 2 have the EVOH film according to the present invention, and the film laminated with this EVOH film is Ny.
Since it is composed of only 6, the linear cutting property is poor. The laminated films according to Comparative Examples 3 and 5 had the EVOH film according to the present invention, but the stretch ratio of the film containing Ny6 and MXD6 was less than 2.8 times in both MD and TD directions, and thus the easy tearability. And at least one of the straight line cutting properties is defective. Since the film according to Comparative Example 4 was composed of a single layer of Ny6, it had a poor linear cut property and a poor gas barrier property.

[0022]

EFFECT OF THE INVENTION According to the easily tearable laminated film and the method for producing the same according to the present invention, in addition to the excellent easily tearable property and the straight line cutting property, a high gas barrier property can be obtained.

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Claims (2)

[Claims] 1. Containing 40 to 85 parts by weight of nylon 6 (Ny6) and 15 to 60 parts by weight of metaxylylene adipamide (MXD6) (however, Ny6 + MXD6 = 100 parts by weight), M
An easily tearable film having a draw ratio of 2.8 times or more in both the D direction (the moving direction of the film) and the TD direction (the width direction of the film) and an ethylene-vinyl acetate laminated on one side of the easily tearable film. An easily tearable laminated film having a saponified polymer (EVOH) film. 2. A raw film containing 40 to 85 parts by weight of nylon 6 (Ny6) and 15 to 60 parts by weight of metaxylylene adipamide (MXD6) (where Ny6 + MXD6 = 10).
0 parts by weight in MD direction (moving direction of film) and TD
In both directions (width direction of the film), an easily tearable film was produced by stretching at a magnification of 2.8 times or more, and then a saponified ethylene-vinyl acetate copolymer (EV
OH) film is extruded and laminated to produce an easily tearable laminated film.