JPS60235709A - Carbon film - Google Patents

Abstract

PURPOSE:A carbon film that is obtained by forming a specific acrylonitrile polymer into a film and roasting it, thus showing high mechanical strength and high electroconductivity. CONSTITUTION:An acrylonitrile polymer consisting of more than 60wt% of acrylonitrile and less than 40wt% of other polymerizable monomers such as methacrylic acid is dissolved in a solvent such as dimethylformamide, the solution is extruded through a die or slit nozzle into a film, drawn, washed and dried to form a precursor film of acrylonitrile of 0.1-100mum thickness. Then, the film is heat-treated at 200-350 deg.C in an oxidative atmosphere to get flame-resistant structure and heated at 400-3,000 deg.C in an inert atmosphere to give the objective carbon film.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a novel carbon film.

[Background technology]

Although carbon material t') has been a conductor comparable to gold F7'i since 1997, it has rarely been shaped into a film due to its mechanical fragility.

Generally, industrialized carbon films are formed by physically compressing graphite particles.

The carbon film made in this way has a thickness of 0.5
As a film, it is extremely weak, and its mechanical strength is also extremely weak.

Next, when considering a conductive film from five viewpoints,
Generally, industrialized products are made by forming a polymer resin into a film in advance (2) and coating the film with a conductor such as metal using physical methods such as ion/plating/gluing, vacuum deposition, or sputtering. Alternatively, carbon fibers, finely powdered metals, graphite, or other conductors are mixed into a polymer resin, and the mixture is formed into a film.

In other words, these conductive films can be said to be a combination of a polymer resin, which is an insulator, and a conductive substance. This is not only subject to the constraints of the shaping process (it is also greatly affected by manufacturing costs).

Furthermore, those coated using physical methods have problems in adhesion to resin films, abrasion resistance, etc.

When a conductor is mixed into a resin and formed into a film, there is a restriction that the thickness cannot be made less than the size of the mixed substance, and there is a problem that the rotation axis is required to uniformly disperse the conductor. be.

○ Due to the problems of t1 and others, films as t)'+-- materials, which are highly flexible conductors with a thickness of 0.1 mm or less, have not generally been industrialized.

[Purpose of the invention]

The object of the present invention is to obtain a carbon film having high mechanical strength and conductivity.

[Structure of the invention]

That is, the gist of the present invention lies in a carbon film obtained by shaping an acrylonitrile polymer containing at least □ Q wt % of acrylonitrile into a film and firing the film.

The polymer used in carrying out the present invention contains at least 5 Q wt% of acrylonitrile and, if necessary, other comonomers such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, etc. in an amount of less than 40 wt%. It can be produced by aqueous emulsion or suspension polymerization by appropriately combining and aqueous polymerization. Polymerization is carried out batchwise or continuously.

Next, when shaping a film, a film shaping stock solution is prepared using an organic solvent such as dimethylformamide, dimethylacetamide, or dibutyl sulfoxide as a solvent for dissolving the polymer.

This stock solution is shaped by a semi-dry/semi-wet method using a T-die or slit nozzle, stretched, and washed.

After drying, an acrylonitrile precursor film is obtained.

The thickness of the precursor film obtained in this manner is determined by adjusting the gap between the slits in the discharge section of the T-die or slit nozzle, increasing or decreasing the discharge amount, and the stretching ratio. Thickness is 0.1μ
The thickness is preferably 100 μm or more.

That is, when the thickness is less than 0.1 μm, the film itself has no strength, and problems such as cutting and wrinkling occur during the process from stretching to winding.

In addition, if the thickness exceeds 100 μm, the initial oxidation process in the firing stage will not only take a long time (not only will the process in the next carbonization process cause holes in the center of the film thickness, making it hollow). .

Next, this precursor film is subjected to initial oxidation treatment (heat treatment at 200°C to 350°C in an oxidizing atmosphere) to impart a flame-resistant structure to this precursor film.

In this case, the flexibility and strength of the resulting sheet can be improved by stretching and further processing.

Excessive elongation may cause tears parallel to the running direction of the film, and the preferable elongation range is 1% to 20%.

Then, in an inert atmosphere in the carbonization step, the temperature is 400°C to 3000°C.
Heat treated at 'C to form a carbon film.

Also in this carbonization step, the carbon film is
The mechanical tensile strength of the lume can be improved.

The heat treatment temperature in the carbonization step is desirably 1500° C. or lower, especially if a carbon film with high tensile strength is to be obtained.

Further, in order to obtain a carbon film with good conductivity, it is desirable to perform firing at a processing temperature of 2400° C. or higher.

〔Example〕

The present invention will be explained in detail below by way of examples.

Example 1 Composition is acrylonitrile (hereinafter abbreviated as AN) 98w
teI) and methacrylic acid (hereinafter abbreviated as MAA) 2wt
Dimethylformamide IQOml containing 0.1 mol of rhodan soda in a polymer whose specific viscosity is (0,]J' in %
It was continuously prepared by aqueous polymerization under conditions below the ANN train coalescence with K dissolved at 25°C) of 0.20.

Monomer' AN/MAA = 98/2 Monomer/water weight ratio 1/6 Catalyst: Ammonium persulfate/acidic sodium sulfite redox initiator pH: Use sulfuric acid to control pH to 3±0.2 Temperature = 55 °C Average residence time: Near 0 minutes The polymerization pot has an internal volume of 5001, and the above-mentioned monomer, water, catalyst aqueous solution, and sulfuric acid are continuously added dropwise while stirring, and the polymerization rate is continuously increased to 75% while the polymerization pot overflows. The polymerization slurry was taken out in this state, sodium oxalate was added to stop the polymerization, and then it was dehydrated and washed.

The washed and dehydrated wet polymer was molded into an El pellet, and then dried in air at 100 to 130°C.
A polymer was obtained. The obtained polymer particles were pulverized using a pulverizer and transferred to the next film shaping step.

The polymer powder was dissolved in dimethylformamide, and 26
A wt% stock solution was prepared, and the stock solution was defoamed and kept at 80° C. to obtain a film-forming stock solution.

This stock solution was applied to a thickness of 1.5 mm using the normal semi-dry-semi-wet method. O
A TTM breaker film was obtained.

In film shaping, original yf (was ejected from a nozzle with a slit length of 50 mm and a slit gap of ]OOttm, and after traveling up 5 layers in -1fi air, 1
The film was introduced into a 75 wt % dimethylformamide aqueous solution kept at 0°C to complete coagulation, and then stretched 5 times while being washed in hot water. Then, it was treated with an oil agent, dried, and rolled up.

The obtained breaker film was heated in air at 200°C.
After being elongated by 5% in a heat treatment furnace with a temperature gradient of 270"C, flame resistance treatment was performed.

Next, carbonization was carried out in a heat treatment furnace with a temperature increase gradient from 400°C to 1500"C in nitrogen while elongating by 5% to obtain a carbon film N1 with a thickness of 6 μm. Further, this carbon film N] was Heat treated at 2600°C in nitrogen to a thickness of 5.
A carbon film tooth 2 of 5 μm was obtained.

Table 1 shows the tensile strength of the carbon film NQ] and -2 obtained by the present invention, the industrialized graphite film (manufactured by Nippon Carbon Co., Ltd., Nika Film), and the tensile strength of polyester resin.

Table 2 shows the carbon films obtained by the present invention.
12 shows the volume resistivity of general graphite material, polyester resin, and copper.

Table 1 Table 2 [Effects of the Invention] The carbon film according to the present invention has significantly higher carbon film resistance than graphite films with finely powdered graphite bonded to them or polyester resins used as supports for general conductive films. Has strength. Although it is not as good as copper, which is a good conductor, it has conductivity comparable to graphite material.

Claims (1)

[Claims] A carbon film obtained by shaping an acrylonitrile polymer containing 6 (l wt% or more) into a film and firing the film.