JPS61185437A - Antistatic plastic cushioning packaging material - 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 buffer packaging material used for storing, transporting, and storing articles incorporating parts such as ICs that are susceptible to static electricity damage.

[Conventional technology]

BACKGROUND ART As a cushioning packaging material for articles, a plastic film having a structure in which air is trapped by providing a large number of air chambers between two or more plastic films that are fused together is used, and the plastic film has a large number of independent air chambers. *iE packaging materials for items that are easily susceptible to static electricity damage include antistatic plastic film mixed with an antistatic agent, or conductive plastic film mixed with carbon black, which has a large number of independent air chambers as described above. Materials with a similar structure are used.

However, the effect of antistatic agents is generally not very strong and becomes less effective, especially when the relative humidity decreases,
Furthermore, since carbon black contaminants become opaque, there are drawbacks such as inconvenience in checking the packaged items.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned drawbacks, has a large antistatic effect even under low humidity, and is see-through, making it easy to check packaged items. The purpose is to provide impact packaging materials.

Means for Solving Problem C] That is, the present invention provides two sheets of plastic film each having a transparent conductive coating film made of carbon black as a conductive material on one side, at least one of which has a large number of layers. A cushioning sheet having a plurality of independent air chambers between the two films is constructed by providing a concave portion and pressing the two films into close contact with each other with the conductive coating surface facing outward. This relates to antistatic plus cushioning packaging materials.

A sheet-shaped plastic film packaging material having a large number of independent air chambers is produced by combining two films by the method described in, for example, Japanese Patent Publication No. 34-336 and Japanese Patent Publication No. 16875-1975. It can be manufactured by heating it as it advances to create an airtight air chamber and integrating it.

In the packaging material of the present invention, the surfaces opposite to the surfaces to be crimped onto the two films in advance are transparent and
A conductive carbon black coating must be created. Such a coating film is disclosed in Japanese Patent Application No. 59-46473.
It can be made by the method according to the invention of the present inventors described in the specification of the present invention. That is, as a plastic base material,
Polyvinyl chloride, polyester, polypropylene, polystyrene, polyethylene, etc. are used. Polyethylene has a suitable elongation and is not too rigid, so the air chambers are difficult to tear due to impact force, so it is particularly used as the material of the present invention.

A conductive paint containing carbon black is applied onto this base film to form an extremely thin conductive film that can be seen through. This coating is a layer of carbon black that exhibits electrical conductivity, and it also has many voids that allow light to pass through and be seen through, but it is not practical as a packaging material due to its adhesion and mechanical strength. Since it lacks the physical properties necessary for this, by overcoating it with a transparent synthetic resin layer and providing a transparent synthetic resin surface layer with a volume resistivity of 1X10"Ω-cm or less and a thickness of 10μ or less. A good coating film with improved adhesion and mechanical strength and reduced haze was obtained.Specific examples of the coating film will be further explained in Examples.

In the packaging material of the present invention, it is necessary to apply the above-mentioned conductive coating to both of the two plastic films constituting the packaging material. In the case of a single film, it is not necessarily necessary to apply a conductive coating to both sides of the film, and even a conductive coating applied to only one side has a fairly good antistatic effect, but this In the cushioning packaging material of the invention having a large number of independent air chambers, even if a conductive coating is applied to only one side of the film, the antistatic effect is insufficient.

[Effect]

Since the buffer packaging material of the present invention has a large number of independent air chambers, it has a large impact buffering capacity.

In addition, since both surfaces have conductive coatings, electricity can be easily diffused, so it is difficult to charge static electricity itself, and it is difficult to charge high-voltage static electricity to objects that come into contact with it.
Furthermore, since the conductive coating film can be seen through, it has useful effects such as making it easy to check the items packaged with this material.

Measurement of surface resistance: Surface resistance was measured by measuring the resistance between electrodes as follows. Two long and thin strip-shaped conductive rubber electrodes with a diameter of 10 mm are prepared. Prepare a sample piece with both ends parallel to each other, place the sample on a flat rubber plate, crimp electrodes at right angles to the sample at intervals equal to the width of the sample, and measure the resistance between the electrodes.
This value is the resistance of the square sample surface between the electrodes, that is, the surface resistance. Charging test of aluminum piece A test piece is prepared by attaching a long and thin plastic handle to a thin aluminum plate of near c + w x 7 cm. Holding the plastic handle in your hand, rub the sample to be measured, and measure the potential of the aluminum plate using an electrostatic field measuring device EO03 model manufactured by Rion Co., Ltd.

Example 1 One side of a 50 μm thick polyethylene film was treated with corona discharge, an acrylic polymer solution containing a hydrophilic segment was applied to this side and dried, and 4 parts by weight of conductive carbon black and a surfactant were layered on top of it. A conductive paint consisting of 4 parts by weight, 2 parts by weight of acrylic latex with a non-volatile content of 40%, and 90 parts by weight of water was applied and dried at a rate of 2 g/n, and then an acrylic resin solution containing 2% polyethylene wax was applied on top of it. The coating was applied at a dry weight of 0.8 g/m and dried to obtain a see-through polyethylene film having a surface resistance of 5×10'Ω.

This film was embossed with many hemispherical recesses with a diameter of 101 mm and a depth of 5 mm, and the non-coated sides of the film were heat-sealed with another unembossed film to form a large number of air chambers. A buffer packaging material having conductive coating films on both sides was obtained. This material could easily see through the packaged object.

Place the embossed surface of this packaging material in contact with a grounded metal plate, rub the smooth surface vigorously 50 times with the aluminum piece described in the section of the electrification test on aluminum piece, and measure the potential with a Rion electrostatic field meter. Then, it was less than 2 volts. It was found that this material accumulates almost no static electricity even when it rubs against an aluminum piece.

Comparative Example 1 #ik impact bag packaging material having multiple air chambers made of polyethylene mixed with a commercially available antistatic agent The electrostatic charge of an aluminum piece similar to Example 1 was measured to be 2500 volts.

Comparative Example 2 In Example 1, as another non-embossed film to match the embossed film, a 50 μm thick antistatic polyethylene kneaded with a commercially available antistatic agent was used without using the conductive film of the present invention. By repeating the same operation using the film, a packaging material having one side of the conductive film of the present invention and the other side of a conventional antistatic film was produced. The surface resistance of the antistatic film was 5 x 10''' ohms at 50% relative humidity. The triboelectric charging of an aluminum piece with this material was measured to be 1500 volts.

〔Effect of the invention〕

The buffer packaging material of the present invention has high conductivity on both surfaces.
Because it has a coating layer that has a high ability to dissipate static electricity and makes it difficult to charge other objects, it cannot be used as a buffer packaging material that does not have antistatic ability, such as conventional cushioning packaging materials made from plastic films mixed with antistatic agents. It is not perfect, but it is complete, and has useful effects such as being able to see through the packaged items.

Claims (1)

[Claims] (1) Two plastic films with a transparent conductive coating made of carbon black as a conductive material on one side,
At least one of the films is provided with a large number of recesses, and the two films are pressed into close contact with each other with the conductive coating surface facing outward to form a cushioning sheet having a large number of independent air chambers between the two films. An antistatic plastic cushioning packaging material characterized by the following properties: