JP2845685B2 - Tear-resistant laminate film - Google Patents

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 an easily tearable bag using the same, and can be used as a packaging bag for foods, medicines, industrial products and the like.

[0002]

BACKGROUND ART In recent years, films such as linear low-density polyethylene (L-LDPE) have been frequently used as seal base material (sealant) films for packaging bags of foods, medicines and the like. However, this L-LDPE film is safe because of its excellent sealing strength, but has a large tear resistance, so that it cannot be cut straight along the cut when used and has a problem in opening. Thus, various proposals have conventionally been made for imparting easy tearability and straight-line cutability to the film.

For example, (a) a laminate film having a uniaxially stretched film as an intermediate layer (Japanese Patent Publication No. 58-3)
No. 8320, Japanese Patent Publication No. 55-31725), (b) a structure in which fine scratches are made on the surface of the front base film to facilitate opening,
(c) There is a configuration in which an opening tape is attached to the opening portion of the film.

[0004]

In the structure according to the above (a), the number of intermediate layers is increased by one, and the material cost and the processing cost for laminating are increased. Further, although a uniaxially stretched film is interposed in the intermediate layer, the uniaxially stretched film does not contribute much in strength. In the configuration according to the above (b), the linear cutability is governed by the characteristics of the base material, even if the front base material film is finely scratched and easily opened. In addition, since the surface is damaged even if it is fine, there is a concern about strength.

In the configuration according to the above (c), the cost is increased due to the opening tape, and the productivity is deteriorated. on the other hand,
The present applicant has filed Japanese Patent Application No. Hei 3-308427,
(Ny6) is 40 to 85 parts by weight and metaxylylene adipamide (MXD6) is 15 to 60 parts by weight (however, Ny6 + MXD
6 = 100 parts by weight), MD direction (moving direction of film) and TD direction (width direction of film) during stretching.
We proposed an easily tearable film with both magnifications of 2.8 or more.

[0006] The easily tearable film has good straight-line cutability as well as easy tearability. Also, the laminated film in which the easily tearable film is formed as a single layer and the bag using the same must surely have good tearability and straight-line cutability of the easily tearable film itself. Is desired. Therefore, an object of the present invention is to provide an easily tearable laminated film and an easily tearable bag using the same, which can reliably obtain good tearability and straight-line cutability of the easily tearable film. I do.

[0007]

SUMMARY OF THE INVENTION The present invention provides a
Easy tear laminate fill used to tear straight
A beam, nylon 6 (Ny6) and 40 to 85 parts by weight and m-xylylene adipamide (MXD6) 15 to 60 parts by weight (however, Ny6 + MXD6 = 100 parts by weight) containing, simultaneously
A multi-layer comprising an easily tearable film having a linear cut property and a sealant film with a magnification of at least 2.8 times in both the MD direction (moving direction of the film) and the TD direction (width direction of the film) during biaxial stretching. A laminated easily tearable laminated film, wherein the easily tearable film and the sealant film are laminated adjacent to each other.

[0008] The easily tearable bag according to the present invention is characterized in that the easily tearable laminate film is used and the sealant film is formed as an inner layer.
The chemical formula of MXD6 is shown in Chemical Formula 1 below.

[0009]

Embedded image

The content ratio of Ny6 and MXD6 is N
40 to 85 parts by weight of y6 and 15 to 60 parts by weight of MXD6 (however,
(Ny6 + MXD6 = 100 parts by weight), preferably 50 to 80 parts by weight of Ny6 and 20 to 50 parts by weight of MXD6. When the MXD6 is less than 15 parts by weight, the tearability and the straight-cutting property become poor. In addition, the MXD
When 6 is more than 60 parts by weight, the impact strength is greatly reduced and the practicality is poor.

The easily tearable film contains 40 to 85 parts by weight of Ny6 and 15 to 60 parts by weight of MXD6 (excluding Ny6 + MX).
(D6 = 100 parts by weight), the mixture is melt-extruded, and the cooled raw film is stretched at a magnification of 2.8 times or more in both the MD and TD directions.

The stretching ratio of the raw film is preferably 2.8 times or more in both the MD and TD directions, and is preferably 3.0 times.
More than double. If the draw ratio is less than 2.8,
Easy tearing and straight-line cutting properties are inferior. In addition, the impact strength is reduced, causing a problem in practicality. The stretching is preferably performed by simultaneous biaxial stretching by a tubular method.

Incidentally, necessary additives can be appropriately added to the easily tearable film. Examples of such additives include an antiblocking agent (such as an inorganic filler), a water repellent (such as ethylene bisstearate), and a lubricant (such as calcium stearate).

The easily tearable laminate film according to the present invention contains the easily tearable film as at least one layer,
Any number of layers such as two layers or three layers may be used. However, the more easily tearable film needs to be formed so as to be adjacent to the sealant film. For example, as shown in FIG. 1, a three-layer structure in which the first layer is various sealant films 31, the second layer is the easily tearable film 18, and the third layer is various base films 32, as shown in FIG. An easily tearable laminated film is formed in a four-layer structure in which the first layer is various sealant films 31, the second layer is the easily tearable film 18, and the third and fourth layers are various base films 32 and 33. be able to.

[0015] As the material of the sealant film,
L-LDPE (linear low density polyethylene), LDPE
(Low density polyethylene), HDPE (high density polyethylene), EVA (ethylene-vinyl acetate copolymer), PB
(Polybutene-1), CPP (unstretched polypropylene), ionomer, PMMA (polymethyl methacrylate) and the like, and mixtures thereof can be used.

Examples of the material of the substrate film include PET (polyethylene terephthalate), EVOH (saponified ethylene-vinyl acetate copolymer), PVA (polyvinyl alcohol), PP (polypropylene), and PVD.
A biaxially or uniaxially stretched film such as C (polyvinylidene chloride), HDPE (high density polyethylene), PS (polystyrene) or a non-stretched film can be used. In addition, other than such a resin-based film, a metal film such as an aluminum foil may be used. Examples of the lamination method of the easily tearable laminate film include extrusion lamination, hot melt lamination, dry lamination, and wet lamination.

[0017]

EXAMPLE 1 A mixture of nylon 6 (Ny6) and metaxylylene adipamide (MXD6) at a ratio of 80 parts by weight and 20 parts by weight, respectively, was melt-kneaded at 270 ° C. in an extruder. The melt was extruded from a die having a diameter of 90 mm as a cylindrical film, and then rapidly cooled with water to produce a raw film.

The Ny6 used was Nylon 6 manufactured by Ube Industries, Ltd. (UBE Nylon 1023 FD (trade name), relative viscosity η _r = 3.6), and the MXD6 used was Mitsubishi Gas Chemical ( Metaxylylene adipamide [MX Nylon 6007 (trade name), relative viscosity η]
_r = 2.7].

Next, as shown in FIG. 3, after this raw film 11 is inserted between a pair of nip rolls 12, the raw film 11 is heated by a heater 13 while pressurizing gas thereinto, and an air ring 14 The air 15 was blown further to expand the bubble 16 and the pair was taken up by a pair of nip rolls 17 on the downstream side, thereby performing simultaneous biaxial stretching in the MD and TD directions by the tubular method. The magnification for this stretching is MD
It was 3.0 times in both the TD and TD directions.

Next, the stretched film 18 was placed in a tenter-type heat treatment furnace and heat-set at 210 ° C. to obtain an easily tearable film 18 according to the present embodiment. Next, an L-LDPE film [Unilux LS] was used as the sealant film of the first layer.
-722C (trade name), manufactured by Idemitsu Petrochemical Co., Ltd., thickness 50μ
m], the above-mentioned easily tearable film (each having a thickness of 15 μm) was dry-laminated as a second layer and a third layer to obtain an easily tearable laminated film having a three-layer structure according to the present example.

Next, an easily tearable bag according to the present example was manufactured by using the easily tearable laminate film and using a sealer film as an inner layer by a bag making machine. With respect to the easily tearable laminate film, the linear cut property and the tear resistance were evaluated. The results are shown in Table 1 below.

The straight-line cutability was evaluated as follows. That is, as shown in FIG. 4, the 20cm width of the film 18 nicked 21 at predetermined intervals W _s example 2cm intervals, after tearing the film 18 along these cuts 21, the film piece 18A of the other end 22 measuring the width W _e, the deviation α between the original distance W _s determined as follows. α = _{[(W s -W e) / W} s ] × 100

This measurement was performed on 10 pieces of film 18A, and those having an average value α (%) of less than ± 10% were evaluated as ◎.
(Very good linear cutability), ± 10% ≦ α ≦ ± 30% ○ (Good linear cutability), x (%) exceeding ± 30% × (Poor linear cutability) ). If α (%) exceeds ± 30%, it becomes difficult to cut the film 18 straight.

The tear resistance was evaluated based on the tearing state of the film in a straight cut test. That is, the film that was cut smoothly to the end was evaluated as ◎, the film was caught once or more in the middle, but the film that was cut to the end was evaluated as ○, and the film that was caught in the middle and was not cut to the end was evaluated as ×.

Examples 2 to 8 After the easily tearable film 18 was prepared in the same manner as in Example 1 above,
Each film (L-LDPE, CPP) shown in Table 1 as a sealant film of the first layer, the easily tearable film 18 as a second layer, and each film shown in Table 1 as a base film of the third and fourth layers ( ONy, PET, and OPP) were dry-laminated to obtain a three-layer or four-layer easily tearable laminate film according to each example. Examples 2 to 4, 7,
8 corresponds to the three-layer structure shown in FIG. 1, and Examples 5 and 6 correspond to the four-layer structure shown in FIG.

In the table, NM indicates an easily tearable film according to the present invention, L-LDPE indicates a linear low-density polyethylene film, ONy indicates a biaxially stretched nylon film, and CPP indicates an unstretched polypropylene film. Next, using each easily tearable laminated film, the easily tearable bag according to each example was manufactured using a bag making machine so that the sealant film became an inner layer. And also about the easily tearable laminated film which concerns on each Example, linear cut property and tear resistance were evaluated like Example 1. FIG. The results are shown in Table 1 below.

Comparative Examples 1 to 7 In the case of Comparative Examples 1 to 4, the easily tearable film 18 was used in Example 1
5 and 6, the tearable film 18 is not adjacent to the sealant film 31 of the first layer, that is, between the tearable film 18 and the sealant film 31, as shown in FIGS. Each of the films shown in Table 1 was dry-laminated such that one or more layers of the base films 32 and 33 were sandwiched between them, thereby obtaining a three-layer or four-layer laminated film according to each comparative example.

In the case of Comparative Examples 5 to 7, laminated films having a three-layer or four-layer structure according to each Comparative Example were obtained without using the easily tearable film 18. Next, using each laminated film, a bag according to each comparative example was manufactured by a bag making machine such that the sealant film became an inner layer. And also about the laminated film which concerns on each comparative example, linear cut property and tear resistance were evaluated like Example 1. FIG. The results are shown in Table 1 below.

[0029]

[Table 1]

Consideration of Examples and Comparative Examples From Table 1, according to this example, an easily tearable laminated film is formed by laminating a plurality of layers such that the easily tearable film 18 and the sealant film are adjacent to each other. Therefore, the good straight-line cut property and small tear resistance of the easily tearable film 18 itself can be reliably obtained for any of the laminated films.

On the other hand, in Comparative Examples 1 to 4, since the easily tearable film 18 was included in the laminate film, a good linear cut property and a small tear resistance were obtained, but the easily tearable film 18 and the sealant Since the film and the film are not formed adjacent to each other, better linear cutability and smaller tear resistance as in the embodiment cannot be obtained. According to Comparative Examples 5 to 7, since the easily tearable film 18 was not included in the laminate film, at least one of the linear cut property and the tear resistance was poor.

[0032]

According to the present invention, it is possible to provide an easily tearable laminate film and an easily tearable bag which can reliably obtain good tearability and straight-line cutability of the easily tearable film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one configuration of an easily tearable laminate film according to the present invention.

FIG. 2 is a cross-sectional view showing another configuration of the easily tearable laminate film according to the present invention.

FIG. 3 is a schematic view of a biaxial stretching device used in a method for producing a tearable film according to an example of the present invention.

FIG. 4 is a diagram illustrating a method for evaluating straight-line cut properties.

FIG. 5 is a cross-sectional view illustrating one configuration of a laminate film according to a comparative example.

FIG. 6 is a cross-sectional view showing another configuration of the laminate film according to the comparative example.

[Explanation of symbols]

 11 Raw film 12,17 Nip roll 16 Bubble 18 Tear-resistant film 31 Sealant film 32,33 Base film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 9:00

Claims (2)

(57) [Claims] An easy tear used for tearing in a straight line by hand
A laminated film, nylon 6 (Ny6)
From 40 to 85 parts by weight of metaxylylene adipamide (MXD
6) in an amount of 15 to 60 parts by weight (however, Ny6 + MXD6 = 100 parts by weight), and the magnification in the MD direction (moving direction of the film) and the TD direction (width direction of the film) in simultaneous biaxial stretching are both 2.8 times or more. Easy tear with straight cut property as
And sex film, a tearable laminated film in which a plurality of layers laminated and a sealant film, an easily tearable, wherein said is a tearable film and the sealant film are laminated adjacently Laminate film. 2. An easily tearable bag produced using the easily tearable laminate film according to claim 1, wherein the sealant film is an inner layer.