JPS63209839A - Composite film for packaging - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a packaging composite film used for packaging foods, medicines, etc.

[Conventional technology]

Hitherto, this type of packaging composite film has been known to be made by laminating multiple layers of synthetic resin films such as polypropylene film and high-density polyethylene film. It is also known to use uniaxially oriented film rolls for at least two layers of this synthetic resin film for tightening.

[Problem that the invention seeks to solve]

However, coextruded multilayer films made from polyolefins such as polypropylene and high-density polyethylene do not have polarity, so good adhesion cannot be obtained. Therefore, bags formed from polyolefin composite films may suffer from cracking when opened. The laminated film cannot follow the tearing direction, making it difficult to cut by hand.Also, even if a notch is inserted, the cutting direction after cutting is poor, and the contents cannot be torn in a straight line. It had problems such as spillage.

This invention is intended to eliminate the drawbacks of the conventional products described above.It is an invention that has been invented to solve the above-mentioned drawbacks of the conventional products.While it has excellent heat resistance and surface gloss, it has poor hand-tearability and cutting direction. By layering a high-density polyethylene film with excellent directionality so that it adheres tightly and stretching it in the uniaxial direction, we have created a packaging composite that has the features of both, such as hand-cutting properties, directional cutting properties, and heat-sealing properties. The purpose is to provide film.

[Means to solve the problem]

This invention was invented in view of the above, and is made by coextruding a surface layer made of polypropylene and a back layer made of high-density polyethylene with an intermediate layer made of a polyblend of the above-mentioned polypropylene and high-density polyethylene interposed therebetween. The problem was solved by stretching the laminated composite film 4 to 16 times in the uniaxial direction.

Hereinafter, this invention will be explained in more detail with reference to the drawings.
FIG. 1 is a partially cutaway perspective view of the packaging composite film of the present invention, and FIG. 2 is a partially enlarged sectional view of the same.
is a surface layer made of polypropylene with a density of 0.90 g/cc, 2 is a back layer made of high-density polyethylene with a density of 0.96 g/cc, and 3 is a bond between the surface layer 1 and the back surface N2. The intermediate layer is made of a polyblend of the above-mentioned polypropylene and high-density polyethylene interposed in between, and the polypropylene and high-density polyethylene are blended at a ratio of 50:50, and these composite films is layered by coextrusion and stretched 10 times in the transverse direction so that the total thickness after extrusion is 70μ.

Here, the polypropylene and high-density polyethylene used in the intermediate layer 3 are preferably the same braid as those used in the front layer 1 and the back layer 2,
The blend ratio is 30:70 to 70:30 because the adhesive strength between the surface layer 1 and the back layer 2 is affected by the ratio of polypropylene and high-density polyethylene in the intermediate layer 3.
, preferably 50:50.

If the blend ratio is outside the above range, a cracking phenomenon will occur upon tearing, and the laminated film will not be able to follow the pattern, resulting in poor hand-cutting properties and poor cutting directionality.

Table 1 shows the hand cutability and cutting direction depending on the blend ratio of polypropylene and high density polyethylene forming the intermediate layer 3.

Hand-cutability is the ease with which it can be torn with a fingertip; an O mark indicates that it was easily torn, a Δ mark indicates that it could be torn with a fingernail, and an X mark indicates that it could not be torn with a fingertip. The directionality is the cutting state when a 311 Illl non-chip is inserted in the transverse direction from the edge of the composite film and the film is torn at a speed of 3Qm/win. It shows what wasn't there.

Table 1 Next, the stretching ratio of the composite film must be 4 to 16 times. When the stretching ratio is 4 times or less, the resistance to tearing in the lateral direction is large and it becomes impossible to tear easily with the fingertips, while when the stretching ratio is 16 times or more, tearing occurs easily in the lateral direction, and the moldability becomes difficult. inferior to

Table 2 shows the hand cutability and cutting directionality depending on the stretching ratio of the transversely uniaxially stretched composite film.

Hand tearability is the ease of tearing when torn with a fingertip; ○ indicates that it was easily torn, Δ indicates that it could be torn with a fingernail, and X indicates that it could not be torn with a fingertip. The direction of
When tearing at a speed of 0 m/n+in, the O mark indicates that the direction was almost a straight line, the Δ mark indicates that some parts were not in a straight line, and the X mark indicates that the direction was not in a straight line. It shows.

Table 2 [Effects of the Invention] As is clear from the above, the packaging composite film of the present invention has a polyblend of the above-mentioned polypropylene and high-density polyethylene between the surface layer made of polypropylene and the back layer made of high-density polyethylene. It has excellent adhesive properties because it is layered by coextrusion with an intermediate layer consisting of In order to achieve this, properties necessary for opening the package, such as edge tear resistance and tear strength, ease of hand cutting, and cutting direction, are imparted, and by using polypropylene, which has excellent heat resistance, as the surface layer, heat sealability and surface gloss are achieved. It also has features such as improved hardness and smoothness.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of the packaging composite film of the present invention, and FIG. 2 is a partially enlarged sectional view of the same. I-One surface layer 2-One surface layer 3-One intermediate layer Yuzo-・7* ＼4ヱFigure 1 2B

Claims (3)

[Claims] (1) A composite film layered by coextrusion between a surface layer made of polypropylene and a back layer made of high-density polyethylene, with an intermediate layer made of a polyblend of the above-mentioned polypropylene and high-density polyethylene interposed in a uniaxial direction. A composite film for packaging characterized by being stretched 4 to 16 times. (2) The composite film for packaging according to claim 1, wherein the uniaxial stretching direction is the transverse axis direction. (3) The composite film for packaging according to claim 1, wherein the blend ratio of polypropylene and high-density polyethylene in the intermediate layer is 50:50.