JPH0512036Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention can be used, for example, in liquid crystal substrate glass and IC
The present invention relates to a packaging material used for moisture-proof packaging of items that dislike moisture, such as glass for photomasks used when photoetching onto substrates, or old documents.

[Conventional technology]

Conventionally known moisture-proof packaging materials include polyethylene film and biaxially oriented polypropylene film.

However, when polyethylene film is used, the film has excellent heat welding properties, so bag making and bag mouth sealing can be easily and reliably done by heat welding, and moisture-proof performance decreases due to poor seam sealing. However, the moisture permeability of the film itself measured by the cup method is 20 g/m ² 24 hours at a thickness of 25 μm, and 10 g/m 2 at a thickness of 40 μm.
g/m ² 24 hours, which is large compared to its thickness, and therefore, when packaging items that require high dryness, such as the substrate glass and photomask glass mentioned above, The drawback is that it is necessary to increase the film thickness to lower the moisture permeability, resulting in high costs. In addition, when using biaxially oriented polypropylene film, the film has low moisture permeability and high mechanical strength, making it difficult to break, making it suitable as a moisture-proof packaging material. The bags and closures have poor thermal welding properties, and as a result, it is very difficult to reliably seal the seams, and there are disadvantages in that moisture proofing is likely to occur due to poor sealing. In order to overcome this drawback, packaging materials have been proposed in which a biaxially oriented polypropylene film or paper and a polyethylene film are bonded in a laminated state with an aluminum film sandwiched therebetween (e.g., Japanese Patent Laid-Open No. 167439/1983). .

[The problem that the idea aims to solve]

However, according to the above-mentioned conventional structure, when a biaxially oriented polypropylene film and a polyethylene film are bonded in a laminated state with an aluminum film sandwiched between them, the water vapor permeability can be lowered than that of the polypropylene film alone, and the polyethylene By heat-bonding the films so that they are in contact with each other, the joints for bag making and sealing can be reliably and easily sealed, and furthermore, the aluminum vapor-deposited film is prevented from being damaged or cut due to contact with other objects. However, since it is made of only polypropylene film, polyethylene film, and aluminum vapor-deposited film, it has poor shape retention when making bags, and it is time-consuming to store items. Another disadvantage is that it cannot be expected to have much of a cushioning effect against contact with other objects, and is likely to break due to such contact.

Furthermore, when paper and polyethylene film are bonded in a laminated state with an aluminum film sandwiched between them, it has the advantage of improving shape retention during bag making, but since the paper is placed on the outer surface, It has the disadvantage that it easily absorbs moisture, and when it absorbs moisture, its strength decreases and it becomes easily damaged, and when it is broken, the damaged part grows quickly.

The present invention solves the above-mentioned conventional drawbacks, and has excellent heat weldability and moisture permeation prevention properties for bag making and sealing, good shape retention during bag making, and high strength against contact with other objects. The purpose is to provide packaging materials.

[Means to solve the problem]

In order to achieve the above object, the present invention is characterized in that a biaxially oriented polypropylene film and a polyethylene film are bonded together in a laminated state sandwiching an intermediate layer comprising an aluminum vapor-deposited film and kraft paper. The effects are as follows.

[Effect]

In other words, since the kraft paper is interposed as an intermediate layer and the biaxially oriented polypropylene film and polyethylene film are placed on both sides of the intermediate layer, moisture absorption from the kraft paper from both the front and back sides can be prevented. In addition to reducing moisture permeability and improving thermal weldability, the provision of kraft paper also has advantages such as good shape retention during bag making and cushioning effect against contact with other objects. It is possible to maintain the advantage of excellent performance.

Moreover, since the biaxially stretched polypropylene film is disposed on one outer surface, the mechanical strength of the outer surface can be increased, and the strength against contact with other objects can be increased.

Furthermore, with the combination of biaxially oriented polypropylene film, polyethylene film, and paper,
Expansion force and tear resistance can be increased, and even if a cut portion is generated on the surface due to, for example, glass edge, the growth of the cut portion can be suppressed.

[Effect of idea]

Therefore, it is possible to maintain good shape retention during bag manufacturing and a good buffering effect against contact with other objects, and it is also possible to increase the strength of the packaging material itself and its outer surface, making it extremely moisture permeable. It is possible to securely and easily seal the seams in a lowered state, improve handling properties such as storing items and sealing the opening after storing, and provide highly durable packaging materials. Ta.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

As shown in FIG. 1, the packaging material A is constructed by adhering a biaxially stretched polypropylene film 1 and a polyethylene film 2 in a laminated state with an intermediate layer 3 sandwiched therebetween.

The intermediate layer 3 is made of the polyethylene film 2
The aluminum vapor-deposited film 3A vacuum-deposited on the aluminum vapor-deposited film 3A, the paper 3B, and the paper 3B
It is composed of a polyethylene layer 3C that is thermally welded to A, and a polyethylene layer 3D that is thermally welded to the biaxially stretched polypropylene film 1. The paper 3B is compressed in the longitudinal direction during the papermaking process, has elasticity and flexibility, has high impact resistance, and is less slippery than ordinary paper, making it difficult to bond with resin films. It is a special extensible kraft paper (commonly called Krupak paper) that has good conformability.

To give examples of actual values of the thickness of each element of the packaging material A, the thickness of the biaxially stretched polypropylene film 1 is 20 μm, the thickness of the polyethylene film 2 is 60 μm,
The thickness of polyethylene layers 3C and 3D are respectively
30μ, and the thickness of the aluminum evaporated film 3A is 500Å.As a result of measuring the moisture permeability of the packaging material made with these dimensions using the Cupp method, the moisture permeability was 2.16.
g/m ² for 24 hours. As a result of measuring the moisture permeability by changing the thickness of each element, it was found that sufficient moisture resistance can be ensured if the thickness of the biaxially oriented polypropylene film 1 is 15μ or more and the thickness of the polyethylene film 2 is 50μ or more. There was found.

An example of the packaging method using the packaging material A configured as described above is as shown in FIG. 2.
The packaging material A is processed into a bag shape with the biaxially stretched polypropylene film 1 on the outside, the article to be packaged and a desiccant are stored in the bag-shaped packaging material A, and the air inside is extracted, and then the polypropylene film film 2
The bag opening is closed and sealed by heat welding with the bags stacked one on top of the other.

In addition, when a packaged article wrapped with the packaging material according to the present invention is vacuum-packed, the peripheral edge of the packaged article can be maintained at a uniform strength by the action of the kraft paper.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being a sectional view and FIG. 2 being a sectional view of the device in use. 1... Biaxially stretched polypropylene film, 2...
...Polyethylene film, 3A...Aluminum vapor deposited film, 3...Intermediate layer, 3B...Paper, 3C, 3D
...Polyethylene layer.

Claims (1)

[Claims for Utility Model Registration] 1. A biaxially oriented polypropylene film 1 and a polyethylene film 2 are combined into an aluminum vapor-deposited film 3.
A packaging material formed by adhering layers A and kraft paper 3B sandwiching an intermediate layer 3. 2. A packaging material according to claim 1, in which the aluminum vapor-deposited film 3A is vacuum-deposited on the polyethylene film 2. The packaging material 3 according to claim 1, wherein the intermediate layer 3 is made of aluminum vapor-deposited on the polyethylene film 2. It is composed of a vapor-deposited film 3A, a kraft paper 3B, a polyethylene layer 3C for thermally welding the kraft paper 3B to the aluminum vapor-deposited film 3A, and a polyethylene layer 3D for thermally welding the kraft paper 3B to the biaxially stretched polypropylene film 1. The packaging material according to claim 1 or 2 of the claims for utility model registration.