JPS6037791B2 - A method of blocking liquid permeability to a plastic film and imparting only breathability to it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of blocking liquid permeability to a plastic film and imparting only air permeability to it.

Plastic films are strong, highly water resistant, beautiful and hygienic, but unlike paper, they have the problem of not being breathable.

- On the other hand, this plastic film can be made breathable by making pongee holes, but in this case,
At the same time, liquid permeability also occurs, making it impossible to provide only breathability. In the packaging field, for example, when packaging breathable articles such as fruits and vegetables, a plastic film that is not liquid permeable and has good air permeability is often required as the packaging film.

However, no film suitable for this purpose has been obtained so far. The present invention meets these demands by providing air permeability by perforating a plastic film, and by interposing water-resistant and/or oil-resistant paper between the two perforated films A and B. The plastic film is characterized by blocking the pores of films A and B with a water-resistant and/or oil-resistant paper surface by stacking them together and pressing them together to form a single sheet, thereby blocking liquid permeability to the plastic film. This provides a method for imparting only breathability.

In the plastic films A and B used in the present invention,
The material may be any material, such as polyolefins such as polyethylene, polypropylene, and polybutadiene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 6,6; polyvinyl compounds such as polyvinyl chloride and polystyrene;
Further examples include cellophane.

Of course, as the plastic film in the present invention, in addition to the above-mentioned polymers, films such as copolymers and blends thereof, and laminate films thereof are also applicable. The thickness of this film is usually 10
or more, preferably 20 to 100. In the present invention, first, pores are formed in this film, and the pores in this case are preferably 0.01 to 2 in diameter.
It is about 05 side to 1 side.

If the hole size is too large, the mechanical strength of the plastic film will decrease, and the surface area of the paper exposed to the outside through the holes will become too large, reducing the water and oil resistance of the film. It is best to make it smaller than willow. Examples of preferable perforated films in the present invention are as follows:
Diameter 0.0 for one swim of film with thickness 20~100〃
It has 1 to 100 holes of 5 to 1 willow size. In this way, the film with pongee holes has breathability,
Its air permeability is controlled by the size and number of paper holes. In the present invention, two sheets A and B of plastic films that have been given a certain amount of air permeability in this way are prepared, and the two sheets A and B are prepared.
, B are stacked with water- and/or oil-proof paper sandwiched between them, and the whole is adhered to form an integral sheet.

In this case, any bonding method between the layers may be employed, such as bonding with an adhesive, a heat fusion method using a synthetic resin, and a dry lamination method. Moreover, the adhesion order between each layer is also arbitrary. As the water- and/or oil-resistant paper used in the present invention, various types of conventionally known paper including those whose surfaces have been treated with water-repellent or oil-repellent processing are used. For example, examples of water-resistant paper include paraffin paper, oil paper, and asphalt. Paper, astringent paper, pure white, etc. are available, and oil-resistant paper includes parchment paper, pseudo-parchment paper, etc.

In particular, parchment paper and pseudo-parchment paper are preferred as they have water resistance and oil resistance. The thickness of this water-resistant and/or oil-resistant paper is not particularly limited, and can be appropriately determined in consideration of mechanical strength, flexibility, and the like. In this way, when two perforated plastic films A and B are laminated and bonded together through water- and/or oil-proof paper to form an integrated sheet, the pongee holes perforated on the surface of the plastic film are A,
The hole is closed (covered) by a water-resistant and/or oil-resistant paper interposed between B, and the surface of the water- and/or oil-resistant paper is exposed in the hole.

According to the research conducted by the present inventors, the laminated plastic film formed in this way has a property of being breathable through the pores formed on the plastic surface, but not allowing liquid to pass through it. found.

For example, if a bag made of this laminated film is used as medicine packaging paper and an oxygen absorber is sealed in it, if the bag is left in the air, the sealed oxygen absorber will react with the oxygen in the air. This confirms that oxygen gas permeated the laminated film surface and entered the interior. On the other hand, even after this oxygen absorber sealed package is submerged in water for about a week, no water enters its interior. This confirms that the laminated film surface does not have water permeability. Gas permeability through the surface of the laminated film according to the present invention can be adjusted by the size and number of pores formed in the film surface, that is, the pore area ratio.

P=ki; The pore area ratio P of at least one of the films A and B is preferably 5% or less, usually 0.1 to 2%.

When the laminated film formed according to the present invention is used as a packaging film, a low-temperature heat-melting film such as a polyethylene film is used as the film forming the inner surface, and the outer surface is It is preferable to use a high-temperature melting film such as polypropylene, nylon, polyester, etc. as the film forming the material.

In this way, a laminated film with good heat sealability can be obtained. The film according to the present invention has air permeability, but its water permeability and/or oil permeability is blocked.

If the paper interposed between films A and B is water-resistant or oil-resistant, the laminated film is water-impermeable or oil-impermeable, respectively, and if it is water- and oil-resistant, it is water- and oil-resistant. It is liquid-impermeable. In this way, the liquid impermeability of the laminated film depends on the properties of the paper interposed between films A and B, but in this case, the liquid impermeability of the laminated film can be achieved no matter how the surface of conventional paper is processed. It is a remarkable thing that cannot be done. For example, even if waterproof paper is immersed in water for a long period of time, water will penetrate and become wet, but this does not occur with the laminated film of the present invention. The film formed according to the present invention, which has only air permeability but not liquid permeability, can be applied to waterproof packaging for vegetables, fruits, etc. that have a breathing effect, and its gas absorption properties can be applied to gas-emitting chemical agents. , for example, applied to waterproof packaging of oxygen absorbers, perfumes, deodorizers, and desiccants. Next, the present invention will be explained in more detail with reference to Examples.

Example: Approximately 65 pores of approximately 0.3 ribs were formed in the polyethylene film.
A heat-sealing film A in which blocks were perforated and a heat-resistant film B in which 13/10 pores on the approximately 0.5 side were perforated in a polypropylene film were laminated and bonded via parchment paper.

Next, the film thus formed was used as a medicine packaging material, and an oxygen scavenger (iron powder treated with dilute hydrochloric acid) was hermetically encapsulated by heat sealing.

After this oxygen scavenger encapsulation was placed in a closed space and left overnight, the oxygen concentration in the closed space was examined. the result,
It was confirmed that the oxygen concentration in the sealed space decreased, and oxygen gas in the sealed space entered the drug package through the drug packaging material and was immobilized in the oxygen scavenger. Further, when the interior of the deoxidizing envelope was examined after being immersed in water for one week, no water was found to have entered the interior.

Claims (1)

[Claims] 1. Pores are perforated in the plastic film to give it breathability, and two sheets A and B of this perforated film are stacked with water- and/or oil-proof paper interposed between them so that the whole becomes a single sheet. A method of imparting only air permeability to a plastic film by blocking liquid permeability to the plastic film, the method comprising: closing the pores of films A and B with the surface of water-resistant and/or oil-resistant paper.