JPH0699493A - Easy tearing laminated film and easy tearing bag using the same - Google Patents

Abstract

PURPOSE:To provide an easy tearing laminated film excellent in easy tearing properties and linear cutting properties and also having sufficient strength and an easy tearing bag using this film. CONSTITUTION:In the case of an easy tearing laminated film, first-third layers 31-33 each containing nylon 6 (Ny 6) and m-xylyleneadipamide (MXD 6) are formed so that the Ny 6 content of the first and third layers 31,33 is set to 60-95 pts.wt. and the MXD 6 content thereof is set to 5-40 pts.wt. and the Ny 6 content of the second layer 32 is set to 40-85 pts.wt. and the MXD 6 content thereof is set to 15-60 pts.wt. The ratio of the first third layers 31-33 is set to 1:8:1-4:2:4 and the ratio of the first (or third) layer and the second layer is set to 1:8:2:1 and the ratio of the first and third layers is set to l:22:1 and, in this state, the first - third layers are stretched by 2.8 times or more in both of the MD and TD directions thereof to form an easy tearing film which is, in turn, formed as one layer of a plurality of layers.

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 which is easy to tear and an easily tearable bag using the same, and can be used as a packaging bag for foods, chemicals, industrial products and the like.

[0002]

BACKGROUND ART In recent years, films such as linear low-density polyethylene (L-LDPE) have been widely used as a seal base material (sealant) film for packaging bags for foods, medicines and the like. However, this L-LDPE film is safe because it has excellent sealing strength, but it has a large tear resistance, so it cannot be cut straight along the cut line during use, and there was a problem during opening. Therefore, various proposals have heretofore been made to impart easy tearability and linear cuttability to a film.

For example, (a) uniaxially stretched film (Japanese Patent Publication Sho 58
-38320, JP-B-55-31725) as a laminated film having an intermediate layer, (b) a structure in which the surface of the front substrate film is finely scratched to facilitate opening,
(c) There is a configuration in which an unsealing tape is attached to the unsealing portion of the film.

[0004]

In the structure according to (a) described above, the number of intermediate layers is increased by one, and the material cost and the machining allowance for laminating become high. Further, although a uniaxially stretched film is interposed in the intermediate layer, this uniaxially stretched film does not contribute much in terms of strength. In the configuration according to the above (b), the linear cuttability is governed by the characteristics of the base material even if the front base material film is finely scratched and easily opened. Further, even if it is fine, it scratches the surface, so there is concern about strength.

In the structure according to (c), the unsealing tape causes a high cost and a poor productivity. Therefore, an object of the present invention is to provide an easily tearable laminated film having excellent easy tearability and linear cuttability and also having sufficient strength, and an easily tearable bag using the same.

[0006]

Means and Actions for Solving the Problems The easily tearable laminated film according to the present invention comprises first to first nylon 6 (Ny6) and metaxylylene adipamide (MXD6).
3 layer, the Ny6 content of the first and third layers is 60-95.
Parts by weight, MXD6 content is 5-40 parts by weight, Ny6 content of the second layer is 40-85 parts by weight, MXD6 content is 15-60 parts by weight (provided that each layer is Ny6 + MXD6 = 100 parts by weight, and The second layer has a higher MXD6 content than the first and third layers) and the first to third layers have a layer ratio of 1: 8: 1 to 4: 2: 4 and the first (or third). ) And the second layer have a layer ratio of 1: 8 to 2: 1, and the first and third layer have a layer ratio of 1: 2 to 2: 1, and the MD direction (the moving direction of the film) at the time of stretching. ) And TD direction (width direction of film)
Both of the above-mentioned magnifications are 2.8 times or more to form an easily tearable film, and this easily tearable film is formed as one layer of a plurality of layers.

Further, an easily tearable bag according to the present invention is characterized by being constructed by using the easily tearable laminated film. The content ratio of Ny6 and MXD6 in the first and third layers is 60 to 95 parts by weight of Ny6 and 5 to 40 of MXD6.
By weight, Ny6 is preferably 70 to 90 parts by weight, M
XD6 is 10 to 30 parts by weight. If the amount of Ny6 is less than 60 parts by weight, the pinhole resistance is lowered. Also,
If the amount of Ny6 is more than 95 parts by weight, the linear cut property is deteriorated.

The content ratio of Ny6 and MXD6 in the second layer is 40 to 85 parts by weight of Ny6 and 15 to 60 parts by weight of MXD6, preferably 50 to 80 parts by weight of Ny6 and MX.
D6 is 20 to 50 parts by weight. When the Ny6 is less than 15 parts by weight, the easy tearing property and the linear cutting property are deteriorated. On the other hand, if the amount of Ny6 is more than 60 parts by weight, the impact strength is significantly reduced and the practicality becomes poor. The MX
The chemical formula of D6 is shown in Chemical Formula 1 below.

[0009]

[Chemical 1]

The layer ratio of the first to third layers is 1: 8: 1 to
The ratio is 4: 2: 4, preferably 15:70:15 to 35:30:
35. The layer ratio of the first (or third) layer to the second layer is 1: 8 to 2: 1 and preferably 15:70 to 35:30. If it is smaller than 1/8, the pinhole resistance is lowered.

The layer constitution in the easily tearable film is from the first to the first.
Any number of layers can be used as long as it has the third layer. For example, as shown in FIG. 1, a three-layer structure in which a first layer 31, a second layer 32 and a third layer 33 are sequentially stacked, and as shown in FIG. 2, a first layer 31 and a second layer 31. , 32 and third layer 33 between the fourth layer
There is a four-layer structure with 34 interposed. This fourth layer 34 is
It is also possible to mix all layers and add a new component (Ny6 or MXD6) to the recycled layer having an intermediate compounding ratio of all layers or this recycled layer. The new component is preferably a compounding amount of Ny6 or MXD6 in the middle of the first and second layers.

The stretching ratio of the original film is 2.8 times or more in both MD and TD, preferably 3.0.
More than double. If the draw ratio is less than 2.8 times,
Easy tearing and straight-line cutting properties are inferior. In addition, the impact strength is lowered, causing a problem in practical use. 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 anti-blocking agents (inorganic fillers, etc.), water repellents (ethylene bisstearate, etc.), and lubricants (calcium stearate, etc.).

The easily tearable laminated film according to the present invention includes the above easily tearable film as one layer and may have any number of layers such as two layers and three layers. For example, an easily tearable laminated film having a three-layer structure in which the first layer is the easily tearable film, the second layer is various substrate films, and the third layer is various sealant films can be formed. In this case, the first layer and the second layer
The layer construction may be reversed. Further, an easily tearable laminated film having a two-layer structure in which the first layer is the easily tearable film and the second layer is various sealant films may be used.

Examples of the material of the base film include PET (polyethylene terephthalate), EVOH (saponified ethylene-vinyl acetate copolymer), PVA (polyvinyl alcohol), PP (polypropylene), 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 to such a resin film, a metal film such as an aluminum foil may be used.

The material of the sealant film is
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 (polymethylmethacrylate), etc. and mixtures thereof can be used. Examples of the laminating method of the easily tearable laminated film include extrusion laminating, hot melt laminating, dry laminating and wet laminating.

[0017]

EXAMPLE 1 Nylon 6 (Ny6) and metaxylylene adipamide (MXD6), which are the first layer, were added in an amount of 95 parts by weight and 5 parts by weight, respectively.
Ny6, which is the second layer, which is mixed in a ratio of parts by weight.
And MXD6 in a proportion of 40 parts by weight and 60 parts by weight, respectively, and a third layer, Ny6 and MXD6.
95 parts by weight and 5 parts by weight, respectively, were melt-kneaded at 270 ° C. in three extruders (diameter 40 mm), and then the melt was melted through a circular circular die with a diameter of 90 mm.
Layer / second layer / third layer (layer ratio 1: 2: 1) was extruded as a three-layer film, followed by quenching with water to prepare a cylindrical raw film. In addition, this film is
Corresponds to the three-layer structure shown in.

The Ny6 used was Nylon 6 [UBE Nylon 1023 FD (trade name), relative viscosity η _r = 3.7] manufactured by Ube Industries Ltd., and the one used as MXD6 was Mitsubishi Gas Chemical ( Co., Ltd. Metaxylylene adipamide [MX nylon 6007 (trade name), relative viscosity η
_r = 2.7].

Next, as shown in FIG. 3, after the raw film 11 is inserted between a pair of nip rolls 12, the gas is pressed into the nip rolls 12 and heated by a heater 13, and an air ring 14 is drawn at a stretching start point. More air 15 is blown to expand the bubbles 16, and the bubbles 16 are taken up by a pair of downstream nip rolls 17 to perform simultaneous biaxial stretching in the MD and TD directions by the tubular method. Magnification during this stretching is MD
It was 3.0 times in both the direction and the TD direction.

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 example. Next, this easily tearable film (thickness 15 μm) is used as a surface base film, and L-LDPE film [Unilux LS-722C (trade name), manufactured by Idemitsu Petrochemical Co., Ltd., thickness 50 μm] is a sealant film. As the above, both were dry laminated to obtain an easily tearable laminated film according to this example. Next, an easily tearable bag according to this example was manufactured by using this easily tearable laminated film with a bag making machine.

Tear strength and impact strength (film impact) of the easily tearable film were measured, and the easily tearable property and the linear cut property were evaluated. The results are shown in Table 1 below. The tear strength is measured by MD of the film.
Direction and TD direction were measured according to JIS-Z1702 by measuring the Elemendorf tear strength (kg / cm 2).

The impact strength was measured by using a film impact tester manufactured by Toyo Seiki Co., Ltd., and a semicircular pendulum (diameter: 1/2 inch, weight: 30 kg-cm) was attached to a fixed ring-shaped film. ) Was punched and the impact strength required for punching the film was measured. When the impact strength is 4500 kg ・ cm / cm or more, ○, 4500 kg ・ cm / c
The value less than m was evaluated as x. This impact strength is 4500kg ・ cm
When it is less than / cm, the performance as a surface base material is deteriorated and the practicality as a base material for liquid packaging becomes poor.

Regarding the easy tearability, the Emendorf tear strength value E is ○ when E ≦ 7 kg / cm, 7 kg / cm <E <9
The evaluation was made with kg / cm 3 as Δ and E ≧ 9 kg / cm 2 as ×. E is 9
If it exceeds kg / cm, the easiness of tearing will decrease significantly,
In particular, the straight line cutting property drops sharply.

The linear cuttability was evaluated as follows. That is, as shown in FIG. 4, cuts 21 are made in the film 18 having a width of 20 cm at a predetermined interval W _s, for example, 2 cm, and the film 18 is torn along these cuts 21 and then the other end 22 of the film piece 18A is cut. The width W _e is measured and the deviation α from the original interval W _s is determined as follows. α = [(W _s −W _e ) / W _s ] × 100

This measurement was carried out on 10 pieces of film 18A, and if the average value α (%) was less than ± 10%,
(Linear cut property is very good), ± 10% ≤ α ≤ ± 30% ○ (Linear cut property is good), α (%) exceeds ± 30% × (Linear cut property is poor ). If α (%) exceeds ± 30%, it becomes difficult to cut the film 18 straight. The easily tearable laminated film was similarly evaluated for easy tearability and linear cuttability, and a drop strength test was performed 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 150 cc of an equal amount liquid mixture of water and antifreeze is placed from the height of 2 m with the bag sideways, that is, the front and back surfaces of the bag are Drop 20 times per bag so that it is parallel to the drop point.
It was done by checking whether the bag was broken. The test temperature was -20 ° C. This drop test was carried out on 10 bags, ◎ (not suitable for practical use), (1) suitable for practical use, ○ (resistant for practical use), and 3 or more defective bags ×
(It cannot be put to practical use). Tables 3 and 6
In the column of comprehensive evaluation of, ⊚ indicates very good, ∘ indicates good, and x indicates poor.

Examples 2 to 19 The same as in Example 1 except that the mixing ratio of Ny6 and MXD6, the layer constitution ratio and the draw ratio in the first to third layers were changed as shown in Table 1. The biaxially stretched film 18 according to Examples 2 to 16 was obtained by the manufacturing process. Next, using the easily tearable film (thickness 15 μm) as a front substrate film, and each film shown in Table 2 as a sealant film, both were dry laminated to obtain easily tearable laminated films according to the respective examples. .

The sealant film used in Examples 2 to 15 is an L-LDPE film having a thickness of 50 μm.
The sealant film used in 16 is EVA with a thickness of 50 μm.
The film, the sealant film used in Example 17 is a non-stretched PP having a thickness of 60 μm, and the sealant film used in Example 18 is a film obtained by extruding and laminating PE at a thickness of 20 μm on an L-LDPE film having a thickness of 60 μm (PE side. The sealant film used in Example 19 is an L-LDPE film having a thickness of 80 μm.

Next, an easily tearable bag according to each example was manufactured by using this easily tearable laminated film with a bag making machine. With respect to the easily tearable film 18 according to each example, various characteristics were measured and evaluated in the same manner as in Example 1. The results are shown in Table 2. Also, with regard to the easily tearable laminated film of each example, the easily tearable property and the linear cut property were evaluated in the same manner as in Example 1, and the bag was subjected to a drop strength test. The results are shown in Table 3 below.

Comparative Examples 1 to 11 The same as Example 1 except that the mixing ratio of Ny6 and MXD6, the layer constitution ratio and the draw ratio in the first to third layers were changed as shown in Table 4. Biaxially stretched films according to Comparative Examples 1 to 11 were obtained by the manufacturing process. In addition, Comparative Examples 1 to 4 are single-layer films. Next, the biaxially stretched film (thickness 15 μm) according to Comparative Examples 1 to 11 was used as a front substrate film,
Further, each film shown in Table 6 was used as a sealant film, and both were dry laminated to obtain laminated films according to Comparative Examples 1 to 14.

The sealant film used in Comparative Examples 1 to 11 is an L-LDPE film having a thickness of 50 μm. next,
A bag according to each comparative example was manufactured by using each laminate film with a bag-making machine.

With respect to the films according to each comparative example, various characteristics were measured and evaluated in the same manner as in Example 1. The results are shown in Table 5. Also, with respect to the laminated film of each comparative example, the easy tearing property and the straight line cutting property were evaluated in the same manner as in Example 1, and the drop strength of the bag was tested. The results are shown in Table 6 below.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

Consideration of Examples and Comparative Examples From Tables 1 and 2, the film 18 according to this example shows that nylon 6 (Ny6) and metaxylylene adipamide (MXD6) were used.
The first to third layers containing Ny6 of the first and third layers.
Content of 60-95 parts by weight, MXD6 content of 5-40 parts by weight, Ny6 content of the second layer of 40-85 parts by weight, MXD6 content of 15 parts by weight.
-60 parts by weight (however, Ny6 + MXD6 = 10 for each layer)
0 parts by weight, and the MXD6 content of the second layer is higher than the MXD6 content of the first and third layers), and the layer ratio of the first to third layers is 1: 8: 1 to 4: 2: 4. A film at the time of biaxial stretching, in which the layer ratio of the first (or third) layer to the second layer is 1: 8 to 2: 1, and the layer ratio of the first to third layer is 1: 2 to 2: 1. It can be seen that, since the stretching ratio of No. 2 is 2.8 times or more in both MD and TD, the tear strength is 7.0 kg / cm or less, the tearability is excellent, and the linear cutting property is good or very good. All of them have high impact strength of 6500 kg · cm / cm or more.

From Table 3, the easily tearable film 18 according to this embodiment was obtained by dry laminating both the easily tearable film 18 as a front substrate film and the films shown in Table 2 as sealant films. The film is excellent in easy tearability and has good or very good straight line cutting property, and when it is made into a bag, there is almost no bag breakage in the drop test and it has sufficient practical strength. Recognize.

On the other hand, from Tables 4 and 5, since the films according to Comparative Examples 1 and 2 are single-layer films made of Ny6,
High tear strength and poor linear cutability.
The film according to Comparative Example 3 is a single-layer film containing Ny6 and MXD6, and thus is inferior in linear cuttability. The film according to Comparative Example 4 is a single-layer film made of MXD6, and therefore has poor impact strength.

The films according to Comparative Examples 5 to 7 had the first and third layers, but the content ratios of Ny6 and MXD6 in these layers were out of the content ratio according to the present invention, so that the films were cut straight. Inferior in sex. The film according to Comparative Example 8 is
Even if there are first to third layers, Ny of the layers of the first and third layers
Since the content ratio of 6 and MXD6 deviates from the content ratio according to the present invention, and the layer ratio deviates from the layer ratio according to the present invention,
It is inferior in easy tearing and straight line cutting.

The films according to Comparative Examples 9 to 11 are Nos. 1 to 3
The content ratios of Ny6 and MXD6 in the layer No. 1 are included in the content ratio according to the present invention, and the layer ratios of the first to third layers are within the layer ratio according to the present invention. Since the stretching ratio is less than 2.8 times in both MD and TD, it is inferior in any one or more of tear strength, linear cut property and impact strength. Then, from Table 6, the films according to Comparative Examples 1 to 11 were used as the surface base film, and Table 4 was used.
The laminated films according to Comparative Examples 7 to 9 obtained by dry laminating both the films shown in 1 as sealant films are defective in at least one of easy tearing property, linear cutting property and drop strength.

[0044]

EFFECTS OF THE INVENTION According to the present invention, an easily tearable laminated film and an easily tearable bag which have excellent tearability and linear cuttability and also have sufficient strength can be obtained.

[Brief description of drawings]

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

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

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

FIG. 4 is a diagram showing an evaluation method of linear cuttability.

[Explanation of symbols]

 11 original film 12,17 nip roll 16 bubble 18 easily tearable film 31 first layer 32 second layer 33 third layer 34 fourth layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C08L 77/02 LQW 9286-4J // B29K 77:00 B29L 9:00 4F

Claims (2)

[Claims] 1. The first to third layers containing nylon 6 (Ny6) and metaxylylene adipamide (MXD6), wherein the Ny6 content of the first and third layers is 60 to 95 parts by weight, MX
The D6 content is 5 to 40 parts by weight, and the Ny6 content of the second layer is
40 to 85 parts by weight and MXD6 content of 15 to 60 parts by weight (provided that each layer has Ny6 + MXD6 = 100 parts by weight and the MXD6 content of the second layer is MXD6 of the first and third layers).
Content ratio), the layer ratio of the first to third layers is 1: 8: 1 to 4: 2: 4, and the layer ratio of the first (or third) and second layers is 1: 8 to 2: 1,
The layer ratio of the first and third layers is 1: 2 to 2: 1, and the stretching ratio in the MD direction (film moving direction) and the TD direction (film width direction) is 2.8 times or more. An easily tearable laminated film, comprising an easily tearable film, wherein the easily tearable film is formed as one layer of a plurality of layers. 2. An easily tearable bag characterized by using the easily tearable laminated film according to claim 1.