JPH01257047A - Transparent conductive film and its manufacturing method - Google Patents

Abstract

PURPOSE:To obtain a transparent and conductive resin film superior in wear resistance by a method wherein a specific card web is welded or buried into a low-melting point resin film layer of a transparent thermoplastic resin composite film comprised of resin whose melting point difference is at least a specific temperature and the surface of the web is enclosed with thermoplastic resin. CONSTITUTION:A transparent and conductive film is comprised by welding or burying a card web containing at least a 10wt.% conductive fiber and possessing basis weight of 2-15g/m<2> into a low melting point resin film layer of a transparent thermoplastic resin composite film comprised of resin having a melting point difference of at least 10 deg.C and enclosing further the surface of the web with thermoplastic resin. With the melting point difference of less than 10 deg.C, form stability is bad and uniform film is not obtained. When the conductive fiber is less than 10wt.%, a number of twining times of the conductive fiber within the card web becomes few and the same is inferior in conductivity. Then when the basis weight is less than 2g/m<2>, favorable conductivity is not obtained. When the same exceeds 15g/m<2>, though the conductivity is favorable, transparency is degraded drastically.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention provides a transparent conductive film useful as a functional material in electronic fields and other fields where interference due to static electricity and WL magnetic waves is a problem. Regarding.

<Prior Art> With the recent rapid development of electronic fields, the problems of static electricity interference and electromagnetic interference have come to the fore, and there is a strong demand for the development of low-cost transparent conductive films.

Conventionally, conductive resin films have been made by kneading conductive fillers such as ore, carbon black, and metal powders, and by applying conductive metals or conductive metal oxides to the surface of resin films by vacuum evaporation, sputtering, and IJing. Films with objects attached to them, films made by simultaneous button-making of thermoplastic synthetic pulp and conductive #2 fibers, and then heating and pressure treatment are available.

<Problems to be solved by the invention> However, films containing conductive fillers such as carbon black and metal powder have extremely poor transparency;
Additionally, it has the disadvantage of poor moldability and physical properties. Films made by vacuum deposition, sputtering, etc. have the disadvantage that their conductivity tends to decrease due to friction and the like. In addition, films obtained by making paper from thermoplastic synthetic pulp and conductive fibers are limited to conductive fibers with low specific gravity, and long fibers cannot be used because they have poor dispersion and cannot be used electrically. In order to make contact, a large number of conductive fibers must be used, which has disadvantages such as poor transparency. The present invention solves the problems of the conventional conductive resin films as described above, and provides a novel transparent conductive resin film that is inexpensive, has excellent abrasion resistance, and is also transparent.

<Means for Solving the Problems> The present invention provides (1) a transparent thermoplastic resin composite film made of a resin having a melting point difference of IOC or more, and a low melting point resin film layer containing conductive fibers in an amount of 10% by weight or more; 15. ! 7/7
A transparent conductive film in which a fi2 card web is fused or embedded, and the web surface is further encapsulated with a thermoplastic resin; Summary of a method for manufacturing a transparent conductive film characterized by laminating a card web containing conductive fibers with a basis weight of 2゛~i5F/rIL2 on the melting point m-fat film surface, thermocompression bonding, and further coating with molten thermoplastic resin. shall be.

The thermoplastic composite film used in the present invention must be made of a low melting point polymer and a high melting point polymer, and the difference in melting point between them must be 10C or more. This is because the conductive card web is fused or buried in the low melting point polymer film layer and integrated with the composite film.If the melting point difference is less than 100, the high melting point polymer film will soften, shrink, etc. and the shape will not stabilize. The properties are poor and a uniform film cannot be obtained. An example of such a transparent thermoplastic resin composite film is a one-sided heat-sealable biaxially stretched polypropylene film made by coextruding polypropylene resins having a melting point difference of more than IOC. Also used is a composite film in which polyethylene, polypropylene, or the like is laminated on a polyester or biaxially oriented polypropylene film. Further, as the thermoplastic resin coated on the card web, polyethylene, polypropylene, polyvinyl chloride, etc. are used, and it is preferable to use the same resin as the low melting point resin of the composite film. The coating is extruded and filled onto the carbon nib by an extrusion lamination method and integrated.

The transparent conductive film produced as described above has a conductive layer made of conductive fibers encapsulated and covered with a composite film and a thermoplastic resin coating layer, and is extremely durable.

The conductive fiber used in the present invention may be a fibrous material having conductivity and capable of forming a carded web.
Although not particularly limited, metal fibers, metal-plated fibers, and copper sulfide-attached synthetic fibers are preferably used. Metal: & fibers include stainless steel fibers and aluminum fibers, and metal-plated fibers are generally called chemical plating, in which metal ions in a metal salt aqueous solution are replaced on the fiber surface by a substitution reaction or an oxidation-reduction reaction. The metals are copper, nickel, and gold.

Silver etc. are used. Copper sulfide-attached synthetic fibers are synthetic fibers with a conductive layer made of sulfurized steel formed on the surface of the fibers, and the fibers are not particularly limited as long as they are hydrophobic synthetic fibers, but from an industrial perspective, they are highly heat resistant. Polyester short fibers are preferably used. In addition, a method for imparting conductivity to hydrophobic synthetic fibers is to treat the fibers in an aqueous solution containing a copper salt, a sulfur-releasing compound, and a water@cation compound.
A conductive layer made of copper sulfide is formed on the surface layer of the hydrophobic synthetic fiber, and a hydrophobic synthetic fiber having electrical conductivity is obtained. A card web of the tetraelectric fiber is prepared using a roller card or a flat card and used as it is, or it is used by laminating a plurality of them using a web player or the like.

The card web must contain conductive fibers in an amount of 10% by weight or more, and if the content is less than 10% by weight, the conductive fibers must be included in the conductive fibers. The number of times the fibers become entangled within the card web decreases, resulting in poor conductivity. Also, the basis weight of the card web is 2I/1rL2~15I/
Use one within the range of m2. If the basis weight is less than 2117 m2, good conductivity cannot be obtained as described above, and 15. l
If it exceeds it/m2, the conductivity will be good, but the transparency will drop significantly, which is not preferable.

Next, to show an example of the method for manufacturing the transparent conductive film of the present invention, conductive N, conductive fibers are spun into a predetermined card web using a card machine, conveyed to a lattice, etc., and the composite film conveyed from the other side is It is superimposed on the low melting point resin film surface and is thermocompressed using a press roller or the like at a temperature above the softening point of the low melting point resin, and then is extruded from a T-die extruder or the like to form a layer of molten thermoplastic resin such as polyethylene that becomes the coating layer. They are stacked together, pressed using a press roller and a cooling roller, and simultaneously cooled and rolled to obtain a transparent conductive film.

As described above, the transparent groove-filled film of the present invention has a conductive layer made of conductive fibers within the composite film, and the film has excellent transparency and high durability. Through processing, it is possible to obtain a film with transparent grooves at a very low cost.

Example The present invention will be explained below with reference to Examples.

In addition, the evaluation results in the examples were based on the following measurement method.

Wear test: 5 at a load of 2001 using a J-K5-LO850 friction tester.
It was rubbed 000 times. In addition, the friction cloth is Kaze T71) +3
r was used.

Transmittance: The transmittance "fc" was measured using a spectrophotometer at a wavelength of 550 μm, with the case where there was no sample being set as 100%.

Electromagnetic shield Note 2 Shield Bonges method (Mitsubishi Rayon method) 1000
Evaluation at MHz Spectrum analyzer used is Atopantest-Crack JR4172 Electrical resistance: Cut the sample into a size of 10 cIrL x 10 cIn,
Masking is performed so that only two opposing sides are deposited, and gold is deposited using a vacuum deposition machine. Next, the resistance between the two deposited sides is measured.

Example 1 Conductivity PI1 obtained using the method described below. One-sided heat seal type biaxially stretched polypropylene film HC-OF 25 μm (manufactured by Tokyo Cellophane ■) with a durable card web
Heat sealing surface (low melting point polypropylene film surface)
The card web was laminated and heated and pressed using a roller heated to 140C at a pressure of 3 to 1/α and a speed of 5 m/min to embed the card web in the heat seal layer of the film.

Next, a polypropylene resin with a melt index of 3.5 was extruded and put into an extruder of a laminating machine, and the extruder and processing speed were adjusted so that a 40 μm film was obtained at a die temperature of 290C, and the film was heat-sealed. Extrude onto the card web buried in the surface,
However, a film of 80 μm was obtained by pressurizing and cooling at a pressure of 10 kjL/(m) using a chinigress roll.Also, as Reference Example 1, a film with a thickness of 80 μm in which 40% of carbon particles were mixed was obtained.
A polypropylene film, and as Reference Example 2, a 1.5 d polyester i-fiber with an average fiber length of 5 fl were treated in the same manner as the method for producing a conductive web described below to obtain a conductive web. After adding 10% by weight of this into a synthetic pulp made of polypropylene fibers that has been canted into 5 pieces and making paper, 1
The film was heated and pressurized at 70 C and 20 kg/cML2, and a film having a thickness of 80 μm was evaluated as described below. The results are shown in Table 1.

Preparation of conductive fiber web: Polyester fiber cotton (1°5 (1,51m cut)
It was immersed in a solution such as stannous chloride 10E/13,35% hydrochloric acid 5CC/p at room temperature for 5 minutes. After that, the polyester fiber was taken out and palladium chloride 0.5 fl/-(
Treatment was performed for 5 minutes at room temperature in 2.5 cc/-e tv of 3,35% hydrochloric acid. In addition, all polyester fibers are removed, sulfuric acid steel 501/A, sodium carbonate 3ag
/A# Potassium sodium phosphate 1009/13.67%
A polyester fiber whose surface was coated with copper was obtained by treating it for 20 minutes at 25C in a solution of 30 cc/l of formalin.

This was run on a flat card machine to create a web with a basis weight of 5 g/rIL2. The surface electrical resistance of this web was 1Ω/mouth.

As shown in Table 1, the film according to the present invention has excellent conductivity, transparency, and excellent durability.

Leprosy Example 2 A card web made of conductive fibers obtained by the method described below was laminated with a 15 μm thick low-density polyethylene resin with a melt index of 7 on a 25 μm polyester film, and ffX was applied to the polyethylene side of the composite film.
W and a pressure of 5kP/α with a roller heated to 180C.
The carded web was heated and pressurized at a speed of 7 +lL/min to partially bury the carded web in the polyethylene layer.

Next, the extruder was adjusted to obtain a 50 μm film at a die temperature of 300 C in the extruder of a low-density polyethylene resin full extrusion laminating machine with a melt index of 6.5. The mixture was extruded onto the top, immediately pressurized with a press roll at a pressure of 15 ky/cm, and cooled to obtain a film of 100 capes. The resulting film has an electrical resistance of 6×10
It showed excellent performance with a resistance of 2 Ω/mouth and a transmittance of 60%.

Preparation of conductive web: A 2D polyester fiber cut into 5 pieces was mixed with 5% by weight of copper sulfate, 5% by weight of sodium thiosulfate, and 0.5% by weight of benzyldimethyldodecyl ammonium chloride.
The material was immersed in a 5C solution to raise the temperature, treated at 80C for 20 minutes, washed with water, dried, and applied to a flat card machine to form a web with a basis weight of 5.9/m'.

<Effects of the Invention> The transparent conductive film of the present invention has excellent conductivity and transparency, and can be used as a functional material in electronic-related fields and other fields where electromagnetic interference and electromagnetic interference are a problem. This will make a major contribution.

Patent applicant: Mitsubishi Rayon Co., Ltd.

Claims (2)

[Claims] (1) A card web with a basis weight of 2 to 15 g/m^2 containing 10% by weight or more of conductive fibers is fused or A transparent conductive film which is embedded and whose web surface is further encapsulated with a thermoplastic resin. (2) A card web containing conductive fibers with a basis weight of 2 to 15 g/m^2 is seeded on the low melting point resin film surface of a transparent thermoplastic resin composite film made of resins with a melting point difference of 10°C or more and bonded by thermocompression. A method for producing a transparent conductive film, further comprising coating with a molten thermoplastic resin.