JPH046540B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to oriented polypyrrole films. Organic polymer compounds are generally classified as insulators, but it has become clear that they can become semiconductors or conductors by adding certain compounds. It has become clear that these polymers can be used as p-type or n-type semiconductors in combination with various semiconductors, depending on the selection of additives, and can be applied to electronic materials, batteries, and the like. These polymers include polyacetylene, polypyrrole, poly-p-
Mention may be made of phenylene. However, these conductive polymers are insoluble and infusible, and it is difficult to obtain products in the desired form, which poses an obstacle in terms of application. Among the above polymers, polypyrrole is a conductive polymer that is noteworthy because of its high conductivity and stability in air. This highly conductive polypyrrole is produced by electrolytic oxidation using platinum or gold as an anode (AFDiaz and KKKanazawa, JC
S.Chem.Comm., 1979 ,. 635) is known to be obtained by depositing an insoluble and infusible polymer film on the anode surface.

The oriented polypyrrole film having enhanced electrical conductivity of the present invention can be obtained by stretching or rolling a polypyrrole film obtained by the following or other methods in at least one direction in an inert gas.

That is, the present invention is a method for producing an oriented polypyrrole film having enhanced electrical conductivity, which comprises stretching or rolling a non-oriented or slightly oriented polypyrrole film in at least one direction in an active gas.

In the present invention, the raw material polypyrrole is a polymer or copolymer obtained from pyrrole and its derivatives, particularly an N-alkyl dielectric, but preferably a homopolymer mainly composed of pyrrole. There are various methods for synthesizing it. For example, pyrrole and/or its dielectric material is placed on a working electrode (hereinafter referred to as WE) in an electrolytic solution consisting of an electrolyte, a solvent, and if necessary a small amount of water, and platinum or a conventionally known It is obtained by reacting general-purpose materials under specific conditions.

The pyrrole and its derivatives used in the present invention preferably have high purity, and are preferably purified by distillation before use. Examples of pyrrole derivatives include C _1-5 N-alkyl derivatives, N-phenyl derivatives, alkyl-substituted C _1-5 at the β-position of the pyrrole ring, alkoxy-substituted products, and phenyl-substituted products. The same method described above is also employed when producing polymers from these pyrrole derivatives.

The electrolyte used in the reaction is preferably one that allows the electrolytic oxidation reaction to proceed and when homogeneous polypyrrole is deposited on the anode surface, the polypyrrole exhibits high electrical conductivity.

The required amount of these electrolytes is that the electrolyte is dissolved as a solution and that the electric current necessary for the reaction to proceed is obtained, and the minimum amount is required for pyrrole.
The amount is 0.1 molar equivalent or more, preferably 0.3 molar equivalent or more, and the maximum amount is the amount at which the electrolyte is saturated as an electrolytic solution. The electrolyte concentration in the electrolyte solution normally used varies depending on the solvent, the type of electrolyte, and the amount of water used, but it is usually 0.001M (mol/
) to 2M, preferably 0.05M to 0.5M
It is. Such electrolytes include quaternary ammonium salts and alkali metal salts of various anions. For example, tetraethylammonium bromide,
Tetraethylammonium iodide, tetraethylammonium perchlorate, tetraethylammonium tetraroborate, tetraethylammonium p-toluenesulfonate, tetra-n-butylammonium bromide, tetra-n-butylammonium iodide, n-butylammonium perchlorate, tetrafluoro Examples include tetra-n-butylammonium borate, tetra-n-butylammonium p-toluenesulfonate, tetra-n-butylammonium hydrogen sulfate, lithium perchlorate, lithium nitrate, lithium tetrafluoroborate, and lithium perchlorate.

A part of these dissociated anions of the electrolyte are present in the polypyrrole as additives to form the polypyrrole film.

The solvent used in the reaction is stable under the voltage required for polymerization of pyrrole compounds,
High solubility in electrolytes and water is required. Examples of such solvents are acetonitrile,
Examples include, but are not limited to, benzonitrile, tetrahydrofuran, nitrobenzene, propylene carbonate, hexamethylphosphoramide, etc.
As long as the above conditions are met, those known in the electrolytic reaction are generally used.

The role of water, which is optionally used, is to enhance the effect of an electrolyte and to improve the form in which polypyrrole is precipitated. The amount used varies depending on the type of electrolyte used, and the concentration of water in the electrolyte solution is
0.1M to 5M, preferably 0.3M to 3M.

The cathode material used in the reaction may be any general-purpose material as long as it does not cause defects or alterations in the electrode reaction, and is not particularly limited, but platinum, platinum,
In addition to metals such as gold, copper, and nickel, SnO ₂ , In ₂ O ₃ , or similar conductive materials, carbon electrodes, and the like are used. In addition, when the electrode area of the cathode is larger than that of the anode, the state of precipitation of polypyrrole that is generally produced is better. The ratio of the cathode to the anode surface area is preferably 1.1 times or more, preferably 1.5 times or more, more preferably 2 times or more, particularly preferably 3 times or more.

The electrolysis voltage and electrolysis current are not certain depending on the reaction conditions, but in general, the electrolysis voltage is 1.0 volt or more.
The voltage is preferably 1.5 volts or more, particularly preferably 2 volts or more, and desirably 3.0 volts or less in view of the stability of the electrolytic reaction solvent. The electrolytic current is 0.01 mA/cm ² to 5 mA/cm ² as a current density at the anode, preferably
0.1mA/ ^cm2 to 3mA/ ^cm2 , particularly preferably 0.5m
A/cm ² to 1 mA/cm ² .

The polypyrrole film used in the present invention can also be prepared by the following method [KKKanazawa et al., JPS
Poly. Lett. Ed, (1982) 187]. That is,
A solution of 2 ml of pyrrole and 10 ml of ethanol was poured into 1.9N sulfuric acid in a Petri dish under stirring and left to stand for 15 hours to form a film of polypyrrole on the surface. This polypyrrole contains sulfate ions as a dopant.

The polypyrrole film obtained as described above is non-oriented in X-rays, and the oriented polypyrrole film of the present invention can be oriented to exhibit high conductivity by stretching or rolling it in at least one direction. A polypyrrole film can be obtained.

One example of the stretching method is to grip both ends of the film and stretch it while applying tension.

The stretching speed is 0.01%/min to 200%/min, preferably 0.1%/min to 100%/min, particularly preferably 0.5
%/min to 20% min, and the stretching atmosphere and temperature are in air, preferably in an inert gas such as nitrogen gas, and between 0°C and 300°C, preferably between 10°C and 200°C.
Particularly preferably, the temperature is between 20°C and 100°C.

The stretching ratio is 5% or more, preferably 10% or more, particularly preferably 20% or more, and the maximum stretching ratio is 95% or more.
% or less, preferably 90% or less. Although the polypyrrole film that has been stretched to a predetermined extent may be removed as is, it is generally preferable to heat-set it. The heat fixation temperature varies depending on the purpose, but
It is usually carried out at a temperature above the stretching temperature and below 600°C.

Another example of the method of stretching can be carried out under pressure between rotating rollers.

In this case, the roller peripheral speed is 0.1mm/min ~ 1000
mm/min, preferably 0.5 mm/min to 100 mm/min, particularly preferably 1 mm/min to 10 mm/min, and the temperature, atmosphere, etc. are the same as the above conditions.

The pressure between the rollers is between 10Kg/cm and 1000Kg/cm, preferably between 50Kg/cm and 500Kg/cm.

Another example of a stretching method is between flat surfaces under pressure.

The applied pressure in this case is 10Kg/cm ² to 1000Kg/cm ² ,
Preferably it is 50Kg/cm ² to 500Kg/cm ² .

The oriented polypyrrole film obtained as described above exhibits an orientation peak in its X-ray diffraction pattern, and its electrical conductivity in the orientation direction is also improved compared to non-oriented or poorly oriented polypyrrole films.

Taking the case of a pyrrole homopolymer as an example, it is non-oriented in X-rays and has an electrical conductivity of 1 to 1.
A film heated at 100S/cm is stretched at least 2θ in the direction perpendicular to the stretching direction (equatorial direction).
0.38-0.48, the degree of orientation is 40% or more, preferably 50
% or more, and its electrical conductivity also comes to exhibit performance of 100 S/cm or more.

Here, the degree of orientation is determined according to the following formula, where H° is the half-width of the intensity distribution along 2θ of the orientation peak.

f (degree of orientation) = 180−H°/180×100 (%)] That is, the oriented film has an electrical conductivity that is 1.1 times or more, preferably 1.5 times or more, the electrical conductivity before orientation.

The present invention will be specifically illustrated in Examples below.

The electrical conductivity in the example was measured using a digital voltmeter manufactured by Heuretsu Patscard Co., Ltd. using the four-terminal method.
Calculated from the voltage measured using 3456A.

In the example, X-ray measurements were performed using a Rigaku X-ray diffractometer (No. 4053A 3) using Cu-Kα rays as the radiation source, and using a scintillator to measure the transmitted X-rays of a sample with a thickness of approximately 500 μm. This was done by measuring with a shock counter.

Example 1 A platinum plate with a length of 5 cm and a width of 4 cm as an anode and a platinum plate with a width of 5 cm and a length as a counter electrode were placed in a 300 ml glass electrolytic tank in a separable flask equipped with two electrode insertion ports, a nitrogen gas inlet pipe, and an exhaust port. A 40cm thick copper foil was installed. Next, 200 ml of a propylene carbonate solution containing 0.06 mol/ml of pyrrole and 0.1 mol/ml of tetraethylammonium perchlorate and 2 ml of water were placed in the electrolytic cell. The reaction was carried out for 3 hours at 40 mA (current density 1 mA/cm ² ) while introducing nitrogen into the solution in the form of bubbles. After the reaction was completed, the anode was taken out and washed with propylene carbonate and then acetone, and the black polypyrrole film was peeled off from the platinum plate.

This film has a thickness of 35μ and its electrical conductivity is
It was 85.6S/cm.

This film was slit into strips with a width of 5 mm, gripped with chucks at a distance of 20 mm, stretched 30% at 100%/min, and heat-set at 150° C. for 5 minutes. The electrical conductivity of the obtained film was 154.9S/cm, and its X-ray photograph (transmission observation direction) showed an orientation pattern at 2θ = 0.40 to 0.48 in the direction perpendicular to the stretching direction (equatorial direction). The degree of orientation at =0.4475 was 58.8%. The photo shows a strong X-ray diffraction device manufactured by Rigaku Denki Co., Ltd.
Photographs were taken using D3F and a Philips Cu tube at a camera distance of 5 cm.

Example 2 Same composition as Example 1, current density 0.35 mA/cm
When the reaction time was changed to ² and allowed to react for 3 hours, a film with a thickness of about 12 μm was obtained. Its conductivity was 146.3S/cm. This film was slit into 5 mm strips, gripped with a chuck distance of 20 mm, stretched 30% at 2%/min, and heat-set at 150°C for 5 minutes.The electrical conductivity was measured and found to be 271.0S/cm. It was hot. 2θ=0.4475
The degree of orientation was 59.3%.

Example 3 Using p-toluenesulfonic acid tetraethylammonium salt as the electrolyte and acetonitrile as the solvent,
The reaction was carried out in the same manner as in Example 1, and the electrical conductivity was 60.7S/
A polypyrrole film of cm was obtained. 50%/
When the film was stretched by 50% at a speed of 10 minutes and heat-set at 150°C for 5 minutes, the electrical conductivity of the film was 113.8 S/cm. In the X-ray diffraction photograph of this film, an oriented diffraction pattern was observed at a position of 2θ=0.42 to 0.48 in the direction perpendicular to the stretching direction. The degree of orientation at 2θ=0.4475 was 57.5%.

Example 4 Pyrrole was converted to 1-methylpyrrole, Example 1
The electrical conductivity of the film obtained in the same manner as 1.3×
It was 10 ³ S/cm. 30 at a rate of 0.5%/min.
% stretching, the electrical conductivity was 5.1×10 ^-3 S/cm.

The degree of orientation at 2θ=0.4475 was 43.2%.

Example 5 The film used in Example 1 was heated at 100°C with a linear pressure of 400 using two rolls with a Teflon surface treatment of 20 cm in diameter.
Rolled at kg/cm.

The electrical conductivity of the obtained film was 129.3 S/cm.

The degree of orientation at 2θ=0.4475 was 48.17.

Example 6 Thickness 35μm obtained in Example 1, electrical conductivity 85.6S/
A 15% stretching film was used. The electrical conductivity of the obtained film was 97.6 S/cm, and the degree of orientation was 41.8%.

Claims (1)

[Claims] 1. Increased electrical conductivity characterized by stretching or rolling a non-oriented or low-oriented polypyrrole film at least unilaterally in an inert gas so that the degree of orientation f is 40% or more. A method for producing an oriented polypyrrole film. [Here, the degree of orientation f is calculated by the following formula, where H° is the half-width of the intensity distribution along 2θ at the orientation peak in the equator direction of the X-ray diffraction photograph of the film in the range of 2θ from 0.38 to 0.48. This is what I was looking for. f (degree of orientation) = 180−H°/180×100 (%)]