JP2845680B2 - Easy tearable laminate film and easy tearable bag using the same - 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 uniaxially stretched film (Japanese Patent Publication No. 58
No.-38320, Japanese Patent Publication No. 55-31725) as a laminate film having an intermediate layer, (b) a structure in which the surface of the surface base film is finely scratched and easily opened,
(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. Accordingly, an object of the present invention is to provide an easily tearable laminate film having excellent tearability and straight-line cutability and having sufficient strength, and an easily tearable bag using the same.

[0006]

SUMMARY OF THE INVENTION The present invention provides a
Easy tear laminate fill used to tear straight
A beam, nylon 66 (Ny66) and 40 to 85 parts by weight and m-xylylene adipamide (MXD6) 15 to 60 parts by weight (however, Ny66 + MXD6 = 100 parts by weight) containing, at simultaneous biaxial stretching Both the MD direction (moving direction of the film) and the TD direction (width direction of the film)
2.8 times or more, has linear cut property, MD direction and T
The tear strength is 7.0kg / cm in any direction of D direction.
The following easily tearable film is constituted, and the easily tearable film is formed as one layer of a plurality of layers.

[0007] Further, an easily tearable bag according to the present invention is characterized in that the easily tearable bag is constructed using the above easily tearable laminate film. The chemical formula of MXD6 is shown in Chemical Formula 1 below.

[0008]

Embedded image

The content ratio of Ny66 and MXD6 is as follows:
Ny66 is 40 to 85 parts by weight and MXD6 is 15 to 60 parts by weight (however, Ny66 + MXD6 = 100 parts by weight), preferably 50 to 80 parts by weight of Ny66 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. On the other hand, if the content of MXD6 is more than 60 parts by weight, the impact strength is greatly reduced, and the practicality is poor. And, by containing Ny66, heat resistance can be imparted to the easily tearable film.

[0010] The easily tearable film has Ny66 of 40-85.
15 to 60 parts by weight of MXD6 (excluding Ny66 +
MXD6 = 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).

[0013] 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. For example, an easily tearable laminated film can be constituted by using the first layer as the easily tearable film, the second layer as various base film, and the third layer as various sealant films. In this case, the first layer and the second layer
The configuration of the layers may be reversed.

Examples of the material of the stretched 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.

[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 lamination method of the easily tearable laminate film include extrusion lamination, hot melt lamination, dry lamination, and wet lamination.

[0016]

EXAMPLE 1 A mixture of nylon 66 (Ny66) 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 Ny66 used was Nylon 66 manufactured by Ube Industries, Ltd. (UBE nylon 2026 (trade name), relative viscosity η _r = 3.5), and the MXD6 used was Mitsubishi Gas Chemical Co., Ltd. ) Metaxylylene adipamide [MX Nylon 6007 (trade name), relative viscosity η
_r = 2.7].

Next, as shown in FIG. 1, 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 a gas thereinto. 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 this embodiment. Next, this easily tearable film (thickness 15 μm) was used as a surface substrate film, and an L-LDPE film [Unilux LS-722C (trade name), manufactured by Idemitsu Petrochemical Co., Ltd., thickness 50 μm] was used as a sealant film. Were dry-laminated to obtain an easily tearable laminated film according to this example. Next, an easily tearable bag according to the present example was manufactured using the easily tearable laminate film by a bag making machine.

With respect to the easily tearable film, the tear strength and the impact strength (film impact) were measured, and the easily tearable property and the straight cut property were evaluated. The results are shown in Table 1 below. The measurement of the tear strength is performed by measuring the MD of the film.
The measurement was carried out by measuring the Elmendorf tear strength (kg / cm 2) in the direction and the TD direction according to JIS-Z1702.

The impact strength was measured using a film impact tester manufactured by Toyo Seiki Co., Ltd., and a semi-circular pendulum (1/2 inch in diameter, 30 kg-cm in weight) was fixed on a fixed ring-shaped film. ) And measuring the impact strength required for punching the film. If the impact strength is 4500kgcm / cm or more, ○, 4500kgcm / c
x was evaluated as less than m. This impact strength is 4500kgcm
If it is less than / cm, the performance as a surface substrate will be reduced, and the practicality as a substrate for liquid packaging will be poor.

The above-mentioned tearability is evaluated as follows: The value of the E elementdorf tear strength E is evaluated as follows: E ≦ 7 kg / cm, 、, 7 kg / cm <E <9
kg / cm 2 was evaluated as Δ, and E ≧ 9 kg / cm 2 as ×. E is 9
If it is over kg / cm, the tearability will decrease significantly,
In particular, the straight-line cutability drops sharply.

The straight-line cut property was evaluated as follows. That is, as shown in FIG. 2, 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 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-resistant laminate film was similarly evaluated for tear resistance and straight-line cutability, and a drop strength test was performed on the bag to evaluate practical suitability. The results are shown in Table 2 below.

In the drop strength test, the easily tearable bag (130 mm × 150 mm) containing an equal amount of liquid mixture of water and antifreeze is placed sideways from a height of 2 m from a height of 2 m. Drop 20 times per bag in parallel with the drop point,
This was done by examining whether the bag would break. The test temperature was −20 ° C. This drop test was carried out on 10 bags, and no break was evaluated as ◎ (suitable for practical use), 1 or 2 bags were broken (good), and 3 or more bags were broken.
(Not practical). Tables 2 and 4
In the column of comprehensive evaluation of, ◎ indicates very good, 良好 indicates good, and × indicates bad.

Examples 2 to 11 In the above Example 1, the mixing ratio of Ny66 and MXD6 and the stretching ratio were changed as shown in Table 1, and the production steps similar to those of Examples 2 to 11 were carried out in the same manufacturing steps as in Example 1. Tearable film
I got 18. Next, the easily tearable film (thickness: 15 μm) was used as a surface substrate film, and each of the films shown in Table 2 was used as a sealant film, and both were dry-laminated to obtain an easily tearable laminate film according to each example. .

The sealant film used in Examples 2 to 9 was an L-LDPE film having a thickness of 50 μm.
The sealant film used in Example 10 was cast polypropylene (CPP) having a thickness of 60 μm, and the sealant film used in Example 11 was a film obtained by extruding PE with a thickness of 20 μm on an L-LDPE film having a thickness of 60 μm (P
An easily tearable film is laminated on the E side). Next, an easily tearable bag according to each example was manufactured using the easily tearable laminate film by a bag making machine.

With respect to the film 18 according to each of the examples, various characteristics were measured and evaluated in the same manner as in the first example. The results are shown in Tables 1 and 2. The tearable laminate film of each example was also evaluated for tearability and straight-line cutability in the same manner as in Example 1, and a drop strength test was performed on the bag. The results are shown in Table 2 below.

Comparative Examples 1 to 10 The same procedures as in Example 1 were carried out except that the mixing ratio of Ny66 and MXD6 and the stretching ratio were changed as shown in Table 3 and the same manufacturing steps as in Example 1 were used. An axially stretched film was obtained. Next, the biaxially stretched film (thickness 15 μm) according to Comparative Examples 1 to 8 was used as a surface substrate film, and the L-LDPE film (thickness 50 μm) was used as a sealant film, and both were dry-laminated. 8 was obtained. Next, a bag according to each comparative example was manufactured using each laminated film by a bag making machine.

With respect to the film according to each of the comparative examples, various characteristics were measured and evaluated in the same manner as in Example 1. Tables 3 and 4 show the results. Also for the laminate film of each comparative example, the tearability and the linear cut property were evaluated in the same manner as in Example 1, and the test for the drop strength of the bag was performed. The results are shown in Table 4 below.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

Discussion of Examples and Comparative Examples From Table 1, it is found that the easily tearable film 18 according to the present example is Ny6
6 and MXD6, and the content ratio of Ny66 is 40 to 85.
Parts by weight, the content of MXD6 is 15 to 60 parts by weight,
Since the stretching ratio of the film at the time of biaxial stretching is 2.8 times or more in both the MD and TD directions, the tear strength is 7.0 kg / cm or less and excellent in tearability, and the linear cutability is good or very good. You can see that there is. In addition, each of them has a high impact strength of 5000 kg · cm / cm or more.

As shown in Table 2, the easily tearable film 18 according to the present example was obtained by dry laminating the easily tearable film 18 as the surface substrate film and each of the films shown in Table 2 as the sealant film. Even when the film is made, the film has excellent tearability, good straight line cutability or very good, and has little or no bag breakage in a drop test, and has sufficient practical strength. You can see that.

On the other hand, from Table 3, the films according to Comparative Examples 1, 2, and 3 have draw ratios within the range according to the present invention.
The content of Ny66 is more than 85 parts by weight, while MXD6
Is less than 15 parts by weight (including 0), so that even if the impact strength is sufficient, the linear cutability is poor.

According to Table 4, the films according to Comparative Examples 1, 2, and 3 were used as the front substrate films, and the films shown in Table 4 were used as the sealant films. The laminated films according to Nos. 2 and 3 have no bag breakage in the drop test, and are inferior in straight-line cuttability even if the practical strength is sufficient.

In the films according to Comparative Examples 4 and 5, the stretch ratio was within the range according to the present invention, but the content ratio of Ny66 was
Since the content of MXD6 is less than 40 parts by weight (including 0) and the content of MXD6 is more than 60 parts by weight, the impact strength is poor even if the tearability and the linear cutability are good.

The laminated films according to Comparative Examples 4 and 5 obtained by dry laminating the films according to Comparative Examples 4 and 5 as the surface base film and the films shown in Table 4 as sealant films were used. Good tearability and straight-line cutability, but considerable breakage in drop test, poor practical strength. Comparative Examples 6, 7,
8, the content ratio of Ny66 and MXD6 is within the range according to the present invention, but since the stretch ratio is less than the range according to the present invention, the tearability, the linear cut property and the impact strength are poor. is there.

Then, the films according to Comparative Examples 6, 7, and 8 were used as the front substrate films, and the films shown in Table 4 were used as the sealant films, and Comparative Examples 6, 7, and 8 obtained by dry laminating both were used. Such a laminate film has at least one of easy tearability, straight-line cutability and drop strength.
One is bad.

[0042]

According to the present invention, an easily tearable laminate film and an easily tearable bag having excellent tearability and straight-line cutability and having sufficient strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a biaxial stretching apparatus used in a method for producing an easily tearable film according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a method for evaluating straight-line cut properties.

[Explanation of symbols]

 11 Raw film 12,17 Nip roll 16 Bubble 18 Biaxially stretched film

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FIB29L 9:00 (56) References JP-A-53-83892 (JP, A) JP-A-4-169231 (JP, A) Kaihei 6-55710 (JP, A)

Claims (2)

(57) [Claims] An easy tear used for tearing in a straight line by hand
A laminated film of nylon 66 (Ny6
6) 40-85 parts by weight and metaxylylene adipamide (M
XD6) is 15 to 60 parts by weight (however, Ny66 + MXD6 =
100 parts by weight), and has a linear cut property with a magnification of at least 2.8 times in the MD direction (moving direction of the film) and the TD direction (width direction of the film) during simultaneous biaxial stretching. An easily tearable laminate film comprising an easily tearable film having a tear strength of 7.0 kg / cm or less in any direction, wherein the easily tearable film is formed as a single layer. 2. An easy tear used for tearing in a straight line by hand.
A plastic bag comprising 40 to 85 parts by weight of nylon 66 (Ny66) and 15 to 60 parts of metaxylylene adipamide (MXD6).
Parts by weight (however, Ny66 + MXD6 = 100 parts by weight), and the magnification in both the MD direction (moving direction of the film) and the TD direction (width direction of the film) during simultaneous biaxial stretching.
2.8 times or more, has linear cut property, MD direction and T
The tear strength is 7.0kg / cm in any direction of D direction.
An easily tearable bag comprising the following easily tearable film, wherein the easily tearable film uses an easily tearable laminated film formed as one layer of a plurality of layers.