JPH0532217B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a conductive plastic foam sheet or film (hereinafter simply referred to as a sheet) and a method for manufacturing the same.

[Prior Art] In recent years, conductive plastics have been used for various purposes as essential for removing static electricity and grounding various objects.

Particularly in the ever-expanding IC industry, ICs themselves are rapidly becoming more integrated, which not only makes them susceptible to destruction by static electricity, but also makes the surrounding environment susceptible to static electricity and electromagnetic wave pollution. As a measure to prevent static electricity, IC components are packaged using conductive plastic foam sheets.

Such conductive plastic foam sheets have conventionally been made by molding a composition into a predetermined shape and foaming it by mixing a plastic containing a foaming agent with a conductive material such as carbon or metal powder. A plastic foam sheet whose surface is coated with a conductive paint or the like to impart conductivity is used.

However, among these, the former type of conductive foam sheet is often cut into multiple sheets, but at this time, "chips" adhere to it.
It has the disadvantage of contaminating products such as IC parts.
In addition, the latter has disadvantages in that the conductive coating layer impairs the flexibility of the foam sheet and is easily washed off by water during use, resulting in a short service life. (For example, Japanese Unexamined Patent Application Publication No. 102931/1982) [Object of the Invention] The present invention was made to eliminate these drawbacks, and has a low electrical resistance value on the surface, which is the most important as an anti-static measure, and is also excellent. It is an object of the present invention to provide a long-life conductive plastic foam sheet or film having good durability and a method for producing the same.

[Summary of the Invention] The present invention provides a conductive foam film comprising a conductive foam film formed by heating and foaming printed or applied foam ink on one or both sides of an olefin resin foam sheet or film. a plastic foam sheet or film;
It is characterized by printing or applying a conductive foaming ink made by adding and mixing a conductive material to a foaming ink on one or both sides of an olefin resin foam sheet or film, and then heating and foaming the ink. This is a method for producing conductive plastic foam sheets or films.

[Structure of the Invention] The details of the present invention will be explained below with reference to the drawings showing one embodiment.

1 to 3 are cross-sectional views showing an example of a conductive plastic foam sheet according to the present invention.

In Fig. 1, reference numeral 1 is a conductive foam film;
This is an example of a conductive plastic foam sheet formed on one side of an olefin resin foam sheet 2. FIG. 2 shows an example of a conductive plastic foam sheet in which a conductive foam film 1 is formed on both sides of an olefin resin foam sheet 2. As shown in FIG.

Furthermore, in the conductive plastic foam sheet of the present invention, a conductive foam film 1 is provided on both sides of the olefin resin foam sheet 2, etc., as shown in FIG. It is also possible to form a structure in which holes 3 are formed, and conductive foam coatings 4 are provided on the inner circumferential surfaces of these through holes 3, respectively, so that both conductive foam coatings 1 are electrically connected.

Next, the fourth method for manufacturing a sheet with such a structure will be described.
This will be explained with a diagram.

In FIG. 4, the foam sheet 2 is sent to a conductive foaming ink layer 5 made by adding and mixing a conductive material, and a foaming ink 6 is printed or coated on one or both sides of the foam sheet in a conductive foaming ink tank 5. and dry it at room temperature. The coated and dried foam sheet 2 is turned over and heated to a temperature of 100 to 140° C. using a heating device 7, for example, an oven to foam the coated layer and form the conductive foamed film 1. The printed or applied conductive foam ink is the foam sheet 2.
The foamed ink fits into the unevenness of the surface and enters the recesses, and by heating and foaming, the foam coating 1 and the foam sheet 2 are softened and integrated with each other, and the foamed ink bites into the recesses of the foam sheet 2 and is perfectly integrated.

The foaming ink used to form the conductive foam coatings 1 and 4 in the present invention is a low-temperature heating type foaming ink whose main component is ethylene-vinyl acetate copolymer or acrylic ester resin. It foams at a high foaming rate of 7 times or more in a short time of 30 to 90 seconds at a low temperature of 100 to 140°C, forming a foamed film with a good appearance.

As the conductive material to be added and mixed, carbon powder, carbon fiber, metal powder, metal fiber, organic oligomer-based conductive treatment agent, inorganic salts, polymer electrolyte, etc. can be used.

In the present invention, a conductive foaming ink obtained by adding and mixing these conductive materials to the foaming ink is thinly printed or applied on the surface of the olefin resin foam sheet 2, etc., and then heated to a temperature of 100 to 140°C. The coating layer is heated to foam and form a conductive foam film.

As the printing or coating method, in addition to screen printing, a coating method using a gravure roll or a textile printing roll, a coating method using a coater knife can be used.

[Embodiments of the invention] Examples of the present invention will be described below.

Example A conductive foaming ink made by adding and mixing 20 parts by weight of Ketin Black to 100 parts by weight of a foaming ink whose main component is ethylene-vinyl acetate was applied to a 4 mm thick foamed polyethylene sheet (Softlon, product of Sekisui Chemical Co., Ltd.). It was coated on one side of the film at a rate of 30 g/m ² using a 40-mesh gravure roll, air-dried at room temperature, and then placed in an oven at 120°C and heated for 80 seconds to foam the coated layer.

The resulting sheet had a conductive foam film integrated with the foam sheet by baking, and had sufficient cushioning properties.

In addition, when we measured the surface resistivity of the conductive foam film on this sheet, we found that it was as low as 10 ⁶ Ω or less, indicating that it has higher conductivity than normal Softlon (surface resistivity 10 ¹⁶ Ω or more). I found out that there was.

[Effects of the Invention] As is clear from the above description, the conductive plastic foam sheet according to the present invention has excellent cushioning properties and the surface conductivity does not deteriorate over a long period of time, so it is suitable for use in IC parts and other applications. It is suitable as a packaging material for preventing static electricity in various products. Note that a foam sheet with a large number of through holes and a conductive foam film provided up to the inner peripheral surface of the through holes has a small volume resistivity. In the present invention, since the olefin resin foam sheet and the foam coating are integrated, the surface of the foam sheet does not become hard and does not lose its flexibility. Olefin resin foam sheets are highly flexible and are not as brittle as polystyrene foam, and chipped powder does not scatter, allowing them to retain their holding power for a long time when, for example, inserting and holding IC component terminals. It will be done.

In the present invention, since the plastic foam sheet and the foam coating are integrated, the surface of the foam sheet does not become hard or lose its flexibility.

Further, according to the manufacturing method of the present invention, such a conductive plastic foam sheet can be efficiently manufactured.

In addition, in the method of the present invention, since the conductive foaming ink printed or applied on the foam sheet is heated and foamed, the two are perfectly integrated and the conductive layer does not fall off, resulting in a long service life and no restrictions on use. It is also easy to use with less effort.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing an example of the structure of a conductive plastic foam sheet or film according to the present invention, and FIG. 4 is an explanatory diagram showing an example of the method of the present invention. It is. 1, 4... Conductive foam film, 2... Olefin resin foam sheet, 3... Through hole.

Claims (1)

[Scope of Claims] 1. A conductive plastic foam characterized in that a conductive foam film is provided on one or both sides of an olefin resin foam sheet or film by heating and foaming a printed or applied foaming ink. Body sheet or film. 2 A conductive foam film is provided on both sides of the olefin resin foam sheet or film, and a large number of through holes are drilled from the front surface to the back surface and the conductive foam film is provided on the inner peripheral surface. A conductive plastic foam sheet or film according to claim 1. 3. A conductive foaming ink made by adding and mixing a conductive material to a foaming ink is printed or applied on one or both sides of an olefin resin foam sheet or film, and then heated to cause foaming. A method of manufacturing a conductive plastic foam sheet or film.