JPH0732469A - Polyamide resin stretched film and bag body consisting of this film - Google Patents

Abstract

PURPOSE:To provide a polyamide resin stretched film and a bag consisting of this film having an adequate strength during prservation, and suitable for a packaging film used in foods, medicines, and the like being easily openable at the time of opening. CONSTITUTION:The easily tearing polyamide resin stretched film is characterized in such that, in a polyamide resin stretched film having a thickness of 40mum or lower, the tearing resistive value in the film winding direction measured in accordance with the act of JISK7128A with respect to the film is 2/3 or lower of the tearing resistive value in the direction normal to the winding direction, and the laminated film is such that another transparent plastics film is laminated at least on one face of the film, and further the bag is constituted of this laminated film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a food product which has sufficient strength during storage and can be easily opened when opened.
The present invention relates to a polyamide resin stretched film suitable for a packaging film for medical products, medicines and the like, and a bag body made of this film.

[0002]

2. Description of the Related Art Conventionally, a uniaxially stretched film of a polyolefin-based resin is liable to be specifically torn in a longitudinal or transverse direction, so that it can be used alone as an easily openable package, or
It has been used by stacking with other films. However, a uniaxially stretched film made of a commonly used polyolefin resin has a relatively low strength, so that the package may be broken during packaging, transportation, or drop during display. there were. For this reason, it is often used by laminating with a polyamide resin film or the like, but there is a drawback that the cost becomes high,
It was only used for luxury items.

On the other hand, in general, the easily-openable film is often produced by a uniaxial stretching method by stretching between rolls. Polyamide-based resin film uniaxially stretched in the winding direction of the long film by this method, unlike the case of the film of olefin-based resin, has the property that it is easy to tear in the direction perpendicular to the winding direction of the film. However, there is a drawback in that the direction in which the bag is taken out from the raw material film is limited when the bag is produced by the method. Despite these drawbacks, polyamide-based resin films that are easily torn in the film winding direction have a large potential demand for bags that take advantage of this unique property, and early commercialization has been desired.

[0004]

SUMMARY OF THE INVENTION In view of the above situation, the present invention provides a polyamide resin stretched film having excellent strength as a whole film and being easily tearable in one direction. With the goal.

[0005]

Means for Solving the Problems The inventors of the present invention have completed the present invention as a result of extensive studies on specific technical means for achieving the above object. According to the invention of claim 1, in a stretched polyamide resin film having a thickness of 40 μm or less, JISK7128 is used for this film.
The tear resistance value in the film winding direction measured according to the method A is 2 / of the tear resistance value in the direction perpendicular to the winding direction.
It is an easily tearable polyamide-based resin stretched film characterized by being 3 or less.

According to the second and third aspects of the present invention, in a laminated film obtained by laminating another transparent plastic film on at least one surface of a polyamide resin stretched film, the polyamide resin stretched film has a thickness of 40 μm.
A laminated film characterized in that the tear resistance value in the film winding direction, measured according to JIS K7128A method, is 2/3 or less of the tear resistance value in the direction perpendicular to the winding direction. The invention according to claim 3 is a bag body comprising the laminated film as a constituent element.

The present invention will be described in detail below. The polyamide resin stretched film according to the present invention is mainly made of polyamide as a raw material. In the present invention, polyamide refers to a resin having a main chain mainly composed of amide bonds, and generally,
Nylon 6, Nylon 66, Nylon 12, Nylon 4
No. 6 aliphatic nylon, MX-nylon containing aromatic ring-containing aliphatic nylon, aromatic nylon, etc., copolymerized nylon thereof, or a mixture of these resins.

Specific examples of the starting materials for the above polyamides include lactams such as ε-caprolactam, enanthlactam, lauryllactam, α-pyrrolidone and α-piperidone, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid and 11-amino acid. Ω-amino acids such as aminoundecanoic acid or nylon salts of dibasic acids and diamines are used.

As the above dibasic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,
Suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dodecanedioic acid, hexadecanedioic acid, hexadecenedioic acid, octadecanedioic acid, octadecenedioic acid, eicosadionic acid,
Aliphatic carboxylic acids such as eicosendioic acid, octadecenedioic acid, docosandionic acid, 2,2,4-trimethyladipic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid Acids, aromatic dicarboxylic acids such as phthalic acid, aliphatic dicarboxylic acids containing an aromatic ring such as xylylenedicarboxylic acid, and the like. Examples of diamines include ethylenediamine, trimethylenediamine, tetremethylenediamine, and pentamethylene. Diamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecamethylenediamine, hexadecamethylenediamine, octadecamethylene Aliphatic diamines such as diamines, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, cycloaliphatic compounds such as cyclohexanediamine, methylcyclohexanediamine, bis- (4,4'aminocyclohexyl) methane Examples thereof include aliphatic diamines containing an aromatic ring such as diamine and xylylenediamine.

Further, the polyamide may contain another resin compatible with the polyamide up to a range of 20% by weight. Other resins compatible with polyamides include polyamides not exemplified above and other thermoplastic resins. When the amount of the resin in the case of containing another resin compatible with this in the polyamide exceeds 20% by weight, the mechanical strength of the polyamide decreases, which is not preferable.

To the polyamide, various additives such as lubricants, antistatic agents, antioxidants, antiblocking agents, stabilizers, dyes, pigments and inorganic fine particles should be added within a range that does not affect the properties of the film. You can The easily tearable polyamide resin stretched film according to the present invention has a thickness of 40 μm.
It is essential that it is m or less. When the thickness exceeds 40 μm, the film becomes hard, and when the sealant layer is laminated, the entire film becomes very thick, which makes it unsuitable for soft packaging.

The stretched polyamide-based film according to the present invention is JIS K712 under the conditions of 23 ° C. and 50% RH.
The tear resistance value in the film winding direction measured according to the 8A method is 2 of the tear resistance value in the direction perpendicular to the winding direction.
It must be / 3 or less. The film that is easily torn in the film winding direction is obtained by stretching the film at a higher ratio in the direction perpendicular to the film winding direction with respect to the film winding direction. It is generally understood that, in a polyolefin resin film, crystallization proceeds in the stretching direction, so that the polyolefin resin film is easily torn in the stretching direction. However, in a polyamide resin film, if it is stretched at a higher ratio in a direction perpendicular to the film winding direction, it tends to tear in the film winding direction. Although the mechanism is not exactly known, it is presumed that, during crystallization in the stretching step, strong hydrogen bonds can be formed in the direction perpendicular to the stretching direction. According to the experiments of the present inventors, the film as a whole has excellent strength, and in order to obtain a film that is easy to tear in the winding direction of the film, the tear resistance value in the winding direction of the film is,
It has been found that it is preferable to set it to 2/3 or less of the tear resistance value in the direction perpendicular to it. If the ratio of the tear resistance values in the two directions exceeds 2/3, the film is not torn in the winding direction of the film when it is torn, and is torn obliquely, which is not preferable.

In the stretched film of the polyamide resin according to the present invention, the tear resistance value in the film winding direction measured according to the JIS K7128A method is 2/3 or less of the tear resistance value in the direction perpendicular to the winding direction. It is indispensable, and as a method for producing such a polyamide resin stretched film, for example, the following method may be used.

First, a substantially amorphous and unoriented unstretched film is manufactured by a conventionally known general method. Next, the unstretched film is stretched unstretched in the winding direction or stretched 3 times or less and stretched 3 to 6 times in the direction perpendicular to the winding direction. If the stretching ratio is more than 3 times in the winding direction of the film, crystallization may proceed in the direction perpendicular to the winding direction of the film. Difficult to carry out, and
Not only is the film liable to break, but the film tearability in the winding direction becomes poor, which is not preferable.

The stretching method includes tenter type uniaxial stretching,
Conventionally known stretching methods such as tenter type sequential biaxial stretching, tenter type simultaneous biaxial stretching, and tubular type stretching can be used. Further, the above-mentioned polyamide resin stretched film can be used alone, but when another transparent plastic film is laminated on at least one surface thereof, the sealing property of the film is improved. Other transparent plastic films include low density polyethylene, linear low density polyethylene, ionomer resin, ethylene vinyl acetate copolymer,
Examples thereof include polypropylene and amorphous polyester. As a method for laminating another transparent plastic film, a conventionally known laminating method such as a dry laminating method or an extrusion laminating method is used. Although these films may be non-oriented films, biaxially stretched films can be used for applications requiring mechanical strength. However, in that case, it is necessary to consider the direction in which the film to be laminated is easily torn so as not to destroy the tearability of the stretched polyamide resin film. The thickness of the transparent plastic film is preferably selected in the range of 15 to 80 μm. Further, the transparent plastic film may be printed in advance.

A laminated film obtained by laminating a polyamide resin stretched film and another transparent plastic film on at least one side thereof can be used as a bag body by laminating the ends of transparent plastic films together.
There is no limitation on the method for manufacturing the bag body, and the bag body can be used as a bag body by a conventionally known method such as joint bonding, three-way sealing, envelope bonding, etc. for filling foods, medical products, medicines, etc. Used for.

[0017]

EXAMPLES The contents and effects of the present invention will be described below in more detail with reference to Examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following examples, the tear resistance was evaluated by the following method. Table 1 shows the film structure and the evaluation results. <Tear resistance (g / μm)> Calculate the ratio of the tear resistance value in the direction perpendicular to the winding resistance value to the tear resistance value in the film winding direction measured in accordance with JIS K7128A method under the conditions of 23 ° C. and 50% RH. did.

Example 1 Poly-ε-caproamide (Novamid 1022, manufactured by Mitsubishi Kasei Co., Ltd.) was melted using a 65 mmφ extruder,
The film was extruded from a T-die and adhered to a cast roll at 30 ° C. and rapidly cooled to obtain an unstretched film of about 60 μm. The obtained unstretched film was temperature-controlled while being slightly stretched 1.1 times in the longitudinal direction by a roll-type temperature controller under the condition of 60 ° C., and then both ends of this film were held by tenter clips, In the tenter oven, the film was stretched 4 times in the transverse direction under the condition of 90 ° C. and then heat-treated at 195 ° C. for 6 seconds.

After heat treatment, the film is clipped at both ears held by clips and scraped off, and the product film is wound around a winder for about 15 minutes.
A drawn film having a thickness of μm was obtained. The composition of the film obtained,
The tear resistance was measured by the method described above, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated, and each is shown in Table 1.

Further, one surface of the obtained film was subjected to corona treatment so that the surface tension of the film was 53 dyn / cm, and then the two-component curing type polyurethane adhesives "Adcoat AD-900" and "RT-5" were used as adhesives. (Both manufactured by Toyo Morton Co., Ltd.) at a coating amount (solid content) of 3 g / m ² were used to laminate a linear low-density polyethylene film (HC manufactured by Tokyo Cellophane Co., Ltd.) having a thickness of 40 μm. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it was torn straight. The results are shown in Table 1.

Example 2 Polymeta-xylylene adipamide (MX-Nylon 6007 manufactured by Mitsubishi Gas Chemical Co., Inc.), poly-ε-caproamide (Novamid 1022 manufactured by Mitsubishi Kasei Co., Ltd.), and mixtures thereof (the former and the latter). Mixing ratio with the latter is 40:60
Are melted separately by using three 65 mmφ extruders, laminated in a co-extrusion T-die and extruded as a laminated film having a three-layer structure, and rapidly adhered to a cast roll at 30 ° C. to form an outer layer. About 24 μm poly-ε-caproamide,
Polymetaxylylene adipamide with an intermediate layer of about 16 μm,
A laminated unstretched film having a mixture of poly-ε-caproamide and polymethaxylylene adipamide with an inner layer of about 24 μm was obtained.

The laminated unstretched film obtained was temperature-controlled by a roll-type temperature controller at 60 ° C., then both ends of this film were held by tenter clips, and the temperature was kept at 90 ° C. in a tenter oven. After stretching 4 times in the transverse direction,
Heat treatment was performed at 95 ° C. for 6 seconds. After the heat treatment, the film is clipped at both ears, and the product film is wound on a winder. A layer of poly-ε-caproamide of about 6 μm, a layer of polymeta-xylylene adipamide of about 4 μm, A laminated stretched film having a total thickness of about 16 μm, which was obtained by sequentially stacking layers of a mixture of poly-ε-caproamide and polymethaxylylene adipamide of about 6 μm, was obtained.

The constitution of the obtained film, the tear resistance was measured by the above-mentioned method, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated. Indicated. In addition, a linear low-density polyethylene film having a thickness of 40 μm (Tokyo Cellophane Co., Ltd.) was manufactured by the same procedure as described in Example 1.
Manufactured by HC) were laminated. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it was torn straight. The results are shown in Table 1.

Example 3 In the example described in Example 1, the stretching ratio in the machine direction was 1.
Approximately 15 with the same procedure as in the example except that
A stretched film of μm was obtained. The composition of the film obtained,
The tear resistance was measured by the method described above, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated, and each is shown in Table 1.

Further, a linear low-density polyethylene film having a thickness of 40 μm (HC manufactured by Tokyo Cellophane Co., Ltd.) was laminated in the same procedure as described in Example 1. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it could be torn straight, and the results are shown in Table 1. Example 4 In the example described in Example 1, about 15 μm was obtained by the same procedure as in the example except that the stretching ratio in the transverse direction was set to 5 times.
To obtain a stretched film.

The constitution of the obtained film, the tear resistance was measured by the above-mentioned method, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated. Indicated. In addition, a linear low-density polyethylene film having a thickness of 40 μm (Tokyo Cellophane Co., Ltd.) was manufactured by the same procedure as described in Example 1.
Manufactured by HC) were laminated. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it could be torn straight, and the results are shown in Table 1.

Example 5 About 15 μm was obtained by the same procedure as in Example 1 except that the stretching ratio in the transverse direction was set to 3 times in the example described in Example 1.
To obtain a stretched film. The constitution of the obtained film, the tear resistance was measured by the method described above, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated, and each is shown in Table 1.

In the same procedure as described in Example 1, a linear low-density polyethylene film having a thickness of 40 μm (HC manufactured by Tokyo Cellophane Co., Ltd.) was laminated. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it was torn straight. The results are shown in Table 1. Example 6 In the example described in Example 1, the stretching ratio in the machine direction is 2.
A stretched film of about 15 μm was obtained by the same procedure as in the example except that the stretching ratio was 5 times and the stretching ratio in the transverse direction was 3.5 times.

The composition of the obtained film, the tear resistance was measured by the above-mentioned method, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated. Indicated. In addition, a linear low-density polyethylene film having a thickness of 40 μm (Tokyo Cellophane Co., Ltd.) was manufactured by the same procedure as described in Example 1.
Manufactured by HC) were laminated. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it could be torn straight, and the results are shown in Table 1.

Comparative Example 1 In the example described in Example 1, the stretching ratio in the transverse direction was 6.
At 5 times, an attempt was made to prepare a stretched film by the same method as described in the same example, but the number of breakages increased, and a satisfactory film could not be obtained. Comparative Example 2 In the example described in Example 1, the stretching ratio in the machine direction was 3
A stretched film of about 15 μm was obtained by the same procedure as in the same example except that the stretching ratio in the transverse direction and the stretching ratio in the transverse direction were set to 3.

The constitution of the obtained film, the tear resistance was measured by the above-mentioned method, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated. Indicated. In addition, a linear low-density polyethylene film having a thickness of 40 μm (Tokyo Cellophane Co., Ltd.) was manufactured by the same procedure as described in Example 1.
Manufactured by HC) were laminated. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it could be torn straight, and the results are shown in Table 1.

Comparative Example 3 In the example described in Example 1, the stretching ratio in the machine direction was 4
A stretched film of about 15 μm was obtained by the same procedure as in the example except that the stretching ratio in the transverse direction was 1.2 times. The constitution of the obtained film, the tear resistance was measured by the method described above, and the ratio of the tear resistance value in the direction perpendicular to the winding direction to the tear resistance value in the film winding direction was calculated, and each is shown in Table 1.

Further, a linear low-density polyethylene film having a thickness of 40 μm (HC manufactured by Tokyo Cellophane Co., Ltd.) was laminated in the same procedure as described in Example 1. With respect to the obtained laminated film, a slit was provided in the winding direction of the film, it was torn by hand, and it was evaluated whether or not it was torn straight. The results are shown in Table 1.

[0034]

[Table 1]

The abbreviations in Table 1 have the following meanings. NY6: poly-ε-caproamide MXD: polymeta-xylene adipamide Longitudinal direction: winding direction of long film Horizontal direction: direction perpendicular to winding direction of long film Tear resistance ratio: tear resistance value in winding direction of long film Of the tear resistance in the direction perpendicular to the winding direction

[0036]

EFFECT OF THE INVENTION The stretched polyamide resin film according to the present invention has excellent strength as a whole film, has excellent tearability in the winding direction of the film, and can be easily opened at the time of opening. It has an advantageous effect that it is suitable for a film for packaging foods, medical products, medicines and the like, and its industrial utility value is extremely large.

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Claims (3)

[Claims] 1. A polyamide resin stretched film having a thickness of 40 μm or less, wherein JIS K7
A tear resistance value in the film winding direction measured according to the 128A method is 2/3 or less of a tear resistance value in a direction perpendicular to the winding direction, and an easily tearable polyamide resin stretched film. 2. A laminated film in which another transparent plastic film is laminated on at least one surface of a stretched polyamide resin film, wherein the stretched polyamide resin film has a thickness of 40 μm or less, and JISK71
A tear resistance value in the film winding direction measured according to the 28A method is 2/3 or less of a tear resistance value in a direction perpendicular to the winding direction. 3. A bag body comprising the film according to claim 2 as a constituent element.