JPS6140549B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to a packaging composite film used for packaging pharmaceuticals, seasonings, etc., and its purpose is to impart heat sealing strength and tearability to the sealant layer. It is an object of the present invention to provide a composite film for packaging that has the necessary sealing properties to withstand the load of a filling material, and has excellent tearability, cuttability, and directionality of cutting.

Recently, with the improvement of product packaging technology, the development of packaging films, especially composite films, has become active.
A wide variety of composite films have come to be provided that are tailored to the properties of each product.

Conventionally, development of these composite films has focused primarily on packaging processability, sealability, and other aspects of packaging technology, and product quality maintenance.

As is well known, when used for packaging, especially packaging bags, the film is mechanically processed during packaging, so tearability and cutting direction are not much of a problem, but at the consumption stage, it is generally The packaging is often opened by hand, so being able to easily tear it is an extremely important condition.

In particular, in the case of packaging bags for food and medicine, it is necessary to open each bag before use, so it is important to be able to easily tear and open the bags with your fingertips.

Furthermore, it is desired that this type of packaging bag has the above-mentioned tearability, has a linear cutting direction, and can be torn in a fixed direction. In particular, when the contents are liquid, powder, or granular, if the cutting direction is not consistent, there is a risk that the cut end will cover the entire bag and overflow, and care must be taken when opening the bag by hand.

Therefore, studies have been conducted on the above-mentioned tearability and cutting direction, but since these composite films are made by layering films with the above functions, they cannot be used as packaging composite films. When used, it requires the addition of a sealant layer, resulting in poor moldability and economic efficiency.

The inventors of the present invention have conducted extensive research in view of the above points, and have found that non-oriented films made of resins with low secondary transition points, such as low-density polyethylene films, have been commonly used as sealant layers.
A film made of linear low-density polyethylene with a density of 0.94 g/cc or less, instead of EVA film or ionomer resin film, is stretched 6 to 20 times in the vertical or horizontal direction to a thickness of 10.
It was discovered that by using a uniaxially stretched polyethylene film of ~100 μm, the desired heat-sealing strength, tearability, and cutting direction are excellent, and the composite material is suitable for light packaging and packaging for relatively heavy items. I was able to complete the film.

Embodiments of the present invention shown in the drawings will be described in detail below. FIG. 1 is a cross-sectional view of the composite film of the present invention, in which a urethane adhesive is applied to one side of a base sheet 1 such as aluminum foil or paper sheet. like adhesive 2
This is a composite film formed by layering a sealant layer 3 with a sealant layer 3 interposed therebetween. Sealant layer 3 in the present invention
The thickness is obtained by stretching a film made of linear low-density polyethylene with a density of 0.94 g/cc or less in the vertical axis direction or 6 to 20 times in the horizontal axis direction.
A uniaxially stretched polyethylene film having a thickness of 10 to 100μ, preferably a horizontally stretched polyethylene film having a thickness of 10 to 100μ, which has been stretched 8 to 13 times in the transverse direction, is used.

In addition, in the uniaxially stretched polyethylene film,
When the stretching ratio is less than 6 times, sufficient molecular orientation cannot be obtained and it is not possible to cut linearly when tearing along the stretching direction, while on the other hand, when the stretching ratio is 20 times or more, stretching is difficult. Heat-sealing strength decreases. In addition, if the thickness is less than 10μ, the heat sealing strength will be poor, and the cutting direction will not be imparted and the influence will be lost.
If it is more than μ, the workability and economical efficiency during heat sealing will be poor, and the purpose of the present invention will be defeated.

As is clear from the above, the present invention is a product in which a sealant layer is laminated on one surface of a base sheet such as aluminum foil or paper via an adhesive, and in which the sealant layer has a linear low density of 0.94 g/cc or less. Thickness obtained by stretching a film made of high-density polyethylene 6 to 20 times in the vertical or horizontal direction.
Since it is a uniaxially stretched polyethylene film with a thickness of 10 to 100 μm, it can be easily torn in a straight line with the fingertips without layering a tearable film in addition to the sealant layer as in conventional products.

In addition, since the sealant layer itself is oriented, the present invention is preferably used not only for light packaging but also for packaging relatively heavy fillings.Furthermore, since the sealant layer is integrated, it is extremely suitable for forming bags. It is convenient and can be mass-produced using an automatic packaging machine, which is advantageous in packaging work.

Next, examples of the present invention will be shown, but the present invention is not necessarily limited to these examples.

Example 1 A polypropylene biaxially stretched film with a thickness of 20μ is layered on one side of an aluminum foil with a thickness of 7μ and an elongation of 2.4% (longitudinal direction) and 5.5% (horizontal direction), and the other side is stretched 12 times in the horizontal direction. A composite film was formed by layering horizontally stretched linear low-density polyethylene films having a density of g/cc and having a thickness of 30 μm. The obtained composite film has physical properties such as Elmendorf tear strength (transverse direction) of 156g, end tear resistance (longitudinal direction) of 26.1Kg, and (transverse direction) of 10.4Kg, and can be easily torn with a fingertip, and is easily cut. It was almost linear, and the hand cuttability and cutting direction were good.

Further, the above composite film was doubled so that the sealant layers faced each other, and the stretching direction of the horizontally stretched film was aligned, and the overlapping periphery was heat-sealed to form a bag.
The resulting bag also had excellent hand-cutting properties and cutting direction, similar to the composite film, and also had good heat-sealing strength, as shown in FIG.

Example 2 Thickness: 7μ, elongation: 2.4% (vertical direction), 5.5% (horizontal direction)
A polyester biaxially stretched film with a thickness of 12μ, which has been stretched 3 times in the horizontal direction and 3 times in the transverse direction, is laminated, and the other side is stretched 7 times in the longitudinal direction, with a thickness of 30μ, with a density of 0.930.
g/cc linear low density polyethylene longitudinally stretched films were laminated to form a composite film.

The obtained composite film has physical properties such as Elmendorf tear strength (transverse direction) of 125 g, edge tear resistance (longitudinal direction) of 25.5 kg, and (lateral direction) of 8.1 kg, and can easily be torn with a fingertip, and can be easily cut. It was almost a straight line, and the hand cuttability and cutting direction were both good.

Further, the above composite film was doubled so that the sealant layers faced each other, and the stretching direction of the longitudinally stretched film was aligned, and the overlapped periphery was heat-sealed to form a bag. The resulting bag also had excellent hand-cutting properties and cutting direction, similar to the composite film, and also had good heat-sealing strength, as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of the composite film for packaging of the present invention, and FIG. 2 shows the heat seal strength of the same example. 1...Base sheet, 2...Adhesive, 3...Sealant layer.

Claims (1)

[Claims] 1. A sealant layer layered on one side of a base sheet such as aluminum foil or paper via an adhesive, in which the sealant layer is made of linear low-density polyethylene with a density of 0.94 g/cc or less. 1. A composite film for packaging, characterized in that it is a uniaxially stretched polyethylene film with a thickness of 10 to 100 μm, which is obtained by stretching a film used as a raw material 6 to 20 times in the vertical or horizontal direction. 2 The sealant layer has a thickness of 10 to 100μ and is made by stretching a film made of linear low-density polyethylene with a density of 0.94 g/cc or less by 8 to 13 times in the horizontal axis direction.
The composite film for packaging according to claim 1, which is a transversely stretched polyethylene film.