JPH07297592A - Cold compression molding electromagnetic shielding sheet - Google Patents

Abstract

PURPOSE:To obtain a cold compression molding electromagnetic shielding sheet which is enhanced in critical processing height and where a metal foil is protected against cracking and fracture by a method wherein an aluminum foil specified in thickness and a thermoplastic resin film are joined together with polyurethane resin obtained through a reaction of polyester polyol with aromatic isocyanate. CONSTITUTION:A metal foil 1 and a thermoplastic resin film 3 are joined together with polyurethane resin 2 obtained through a reaction of polyester polyol with aromatic isocyanate, wherein the metal foil 1 is an aluminum foil as thick as 40 to 200mum and its surface layer 4 is 0.15 to 2.0mum in average roughness. The thermoplastic resin film 3 is a polyvinyl chloride film, its skin layer 5 is 1.0 to 8.0mum in average roughness, and polyurethane resin is applied onto the joint surface of either the metal foil 1 or the thermoplastic resin film 3, and then the metal foil 1 and the thermoplastic resin film 3 are joined together. Therefore, a cold compression molding electromagnetic shielding sheet is high in degree of freedom of moldable height and lessened in molding process cost in mass production.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding sheet composed of a metal foil and a thermoplastic resin film, and more particularly to an electromagnetic wave shielding sheet used for cold compression molding using a male mold and a female mold. is there.

[0002]

2. Description of the Related Art It has been conventionally known that a metal foil such as aluminum, iron or copper has an electromagnetic wave shielding property, and a composite sheet obtained by laminating a thermoplastic resin film on this metal foil via an adhesive layer is also available. It is known as a sheet for electromagnetic wave shielding. These are usually punched into a predetermined shape,
In some cases, it is used after being bent. However, in recent years, there has been an increasing demand for improvement of the shield effect and reduction of the dead space inside the telecommunications equipment used,
There has been a demand for the appearance of an electromagnetic wave shielding sheet which is excellent in cold compression molding and which is excellent in continuous moldability. In this case, the above molding is
It is required that the limit forming height can be made as high as possible without causing cracks and breaks in the metal foil and peeling between the metal foil and the thermoplastic resin film.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electromagnetic wave shielding sheet comprising a metal foil and a thermoplastic resin film, which has a high limit working height, cracks and fractures of the metal foil, and metal foil. An electromagnetic wave shield sheet having good cold compression molding processability without peeling from a thermoplastic resin film.

[0004]

The present invention is an electromagnetic wave shielding sheet comprising a metal foil and a thermoplastic resin film, wherein a space between the metal foil and the thermoplastic resin film is obtained by a reaction of a polyester type polyol and an aromatic isocyanate. The electromagnetic wave shielding sheet for cold compression molding, wherein the metal foil is an aluminum foil having a thickness of 40 to 200 μm, which is joined by the polyurethane resin. And preferably, the average roughness of the surface layer surface of the metal foil is 0.15 to 2.0μ, the thermoplastic resin film is made of a polyvinyl chloride film, and the average roughness of the surface layer surface is 1.0. It is an electromagnetic wave shielding sheet for cold compression molding having a size of ˜8.0 μm or more.

The present invention will be described below with reference to the drawings. The drawings show one embodiment of the present invention, FIG. 1 is a cross-sectional view showing the layer structure of an electromagnetic wave shielding sheet before cold compression molding, and FIG. 2 is a schematic perspective view after the processing. That is, in FIG. 1, 1 is a metal foil, 2 is a joining layer made of a polyurethane-based resin obtained by the reaction of a polyester type polyol and an aromatic isocyanate, 3 is a thermoplastic resin film, 4 and 5 are the metal foil 1 and the thermal foil, respectively. The surface layer surface of the plastic resin film 2 is shown. As the metal foil 1, a foil of iron, nickel, copper, zinc, gold, silver, aluminum or the like, an iron foil plated with nickel or zinc, an aluminum foil plated with copper, or the like has advantages and disadvantages as a shield material, but the price is Aluminum foil is suitable because of its punching workability, laminating workability and cold compression molding workability. The aluminum foil referred to here may be an aluminum alloy containing copper, silicon, manganese, magnesium, chromium, zinc or the like as appropriate. If the thickness of this aluminum foil is too thin, it tends to crack or break during cold compression molding. On the other hand, if it is too thick, the price and weight increase, and the rigidity becomes so great that it becomes difficult to laminate the metal foil 1 and the thermoplastic resin film 3 or wind the roll, which is not realistic. Therefore, the thickness of the aluminum foil is preferably 40 to 200 μ. Examples of the thermoplastic resin film 3 include a polyolefin film such as polyethylene and polypropylene, a polyamide film, a polyester film,
Although there are plastic films such as polyvinyl chloride films, polyvinyl chloride films are preferable because of their price and workability. The polyvinyl chloride film means a film obtained by processing a vinyl chloride resin composition containing a stabilizer, a lubricant, a reinforcing agent, a pigment and the like as appropriate into a film. The vinyl chloride resin includes a type in which ethylene or vinyl acetate is copolymerized and a type in which chlorine is added, that is, a post-chlorinated vinyl resin.

As a result of extensive studies on the bonding layer 2 of the metal foil 1 and the thermoplastic resin 3, it was found that a polyurethane-based resin obtained by the reaction of polyester type follyol and aromatic isocyanate as a bonding agent composition is good. . These joining methods are not particularly limited here, but the polyurethane resin is applied to either one of the joining surfaces of the metal foil 1 or the thermoplastic resin film 3, and then the two are attached by joining. can do. These can be applied by a gravure coater, a reverse coater, a die coater, or the like. The electromagnetic wave shielding sheet for cold compression molding of the present invention obtained as described above is molded into a predetermined molding height (H) as shown in FIG. 2 by cold compression molding using male and female molds. And used as an electromagnetic wave shield material.
At this time, it was found that the average roughness of the surface layers 4 and 5 of the metal foil 1 and the thermoplastic resin film 3 is preferably 0.15 to 2.0 μ and 1.0 to 8.0 μ or more, respectively. Is. That is, the average roughness of the surface layers 4 and 5 of the metal foil 1 and the thermoplastic resin film 3 is 0.15, respectively.
If it is less than or equal to μ and less than or equal to 1.0 μ, the molding height (H) at which cold compression molding is possible, that is, the limit working height is significantly reduced. On the contrary, when the average roughness of the surface layer 4 of the metal foil 1 exceeds 2.0 μ, pinholes are easily generated in the metal foil 1 and cause defects such as cracks. Further, if the average roughness of the surface layer surface 5 of the thermoplastic resin film 3 exceeds 8.0 μ, defects such as tearing will occur in the thermoplastic resin film 3 and the critical working height will be significantly reduced.

[0007]

The electromagnetic wave shielding sheet for cold compression molding of the present invention is an electromagnetic wave shielding sheet comprising a metal foil and a thermoplastic resin film, and has a molding height (H) that can be molded for cold compression molding. Since it has a high degree of freedom and the mass-production molding processing cost is low, it is suitable for industrial products.

[Brief description of drawings]

FIG. 1 is a sectional view showing a layer structure of an electromagnetic wave shielding sheet for cold compression molding of the present invention.

FIG. 2 is a schematic perspective view of the electromagnetic wave shielding sheet for cold compression molding of the present invention after processing.

Claims (3)

[Claims] 1. An electromagnetic wave shielding sheet comprising a metal foil and a thermoplastic resin film, wherein the metal foil and the thermoplastic resin film are joined by a polyurethane resin obtained by the reaction of a polyester type polyol and an aromatic isocyanate. The electromagnetic shielding sheet for cold compression molding, wherein the metal foil is an aluminum foil having a thickness of 40 to 200 μm. 2. The average roughness of the surface of the metal foil is 0.15.
The electromagnetic wave shielding sheet for cold compression molding according to claim 1, wherein the electromagnetic wave shielding sheet has a thickness of about 2.0 μm. 3. The electromagnetic wave for cold compression molding according to claim 1 or 2, wherein the thermoplastic resin film is made of a polyvinyl chloride film and has an average surface roughness of 1.0 to 8.0 μm. Shield sheet.