JPS5818227A - Manufacture of acetylene copolymer film excellent in electrical property - Google Patents

Abstract

PURPOSE:To improve the electrical conductance so as to obtain the titled film suitable for a diode, a solar battery, etc., by pressing a polyacetylene film so that it is plastically deformed with proviso that an expression of a specified thickness ratio is satisfied. CONSTITUTION:For example, a catalyst such as titanium tetrabutoxidetriethyl aluminum in solution is applied on the wall surface of a polymerized container, and then acetylene is introduced and polymerized to form a polyacetylene film on the wall surface. Then the film is plastically deformed by a hydraulic compressor with proviso that the expression 1.1<r<3.0 (r denotes the ratio of a film thickness before the compression to a film thickness after the compression) is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an acetylene polymer film (hereinafter referred to as polyacetylene film). In particular, it relates to a method for producing a polyacetylene film with excellent electrical properties.

Since it became possible to directly polymerize polyacetylene into a film, various interesting properties have been revealed. In particular, by incorporating certain compounds into polyacetylene (doping).

For example, the property that electrical conductivity (σ) can be controlled over a wide range from insulator regions to metal regions is attracting attention as a possibility as a semiconductor and conductor material.

As for the manufacturing method of polyacetylene film.

For example, use a catalyst that dissolves uniformly in a solvent, and near the interface between the catalyst solution and gaseous acetylene and the metal.

This catalyst solution is applied to a solid surface such as glass, and acetylene is polymerized to form polyacetylene.
'24 method is known (Special Publication No. 48-32581
issue).

However, since the polyacetylene film obtained by this method has a fibrillar structure, there are many voids in the film, which increases the specific resistance, making it disadvantageous for use as a conductor or semiconductor.

The present inventors solved the above-mentioned problems and conducted extensive studies on a method for producing a polyacetylene film with excellent electrical properties, and as a result, they arrived at the present invention described below.

That is, the present invention relates to a method for producing a polyacetylene film with excellent electrical properties, which is characterized in that when plastically deforming a polyacetylene film under pressure, the plastic deformation process is performed so as to satisfy the following formula.

i, i < r < 3.0 (where r is the ratio of the thickness of the acetylene polymer film before pressing to the thickness of the acetylene polymer film after pressing).

The polyacetylene film referred to herein includes not only acetylene homopolymers, but also substituted acetylenes such as phenylacetylene, alkyl acetylene, other substituted acetylenes/polymers, and copolymers thereof, as well as acetylene ( Substituted product) refers to a film obtained from a copolymer with olefin monomers such as ethylene, propylene, and styrene.

The polyacetylene film used in the present invention.

For example, it is formed at the gas-liquid or solid-liquid interface using a catalyst.

The catalyst used here is a t-glar catalyst type coordination anion polymerization catalyst, which is a combination of transition metal compounds such as titanium and vanadium and organometallic compounds of metals from Groups 1i to 2 of the periodic table. The main focus is The catalyst system is, for example, a titanium compound (Tx(OR)4.R=alkyl group) and an organoaluminum compound (AIR, , R, ,
Alkyl group] is effective, and among them, titanium tetrabutoxide-triethylaluminum is more preferably used.

The catalyst concentration can be selected in various ways depending on the type of transition metal compound and organometallic compound used.9 For example, when using a titanium tetrabutoxide-triethylaluminum system, the T1 concentration is 0.05 mol/1 or more. is preferable, and even better (is 0.2~!1.0
mol/l, 1 fCax7'ri (D %
k ratio is 0.5 to 10. More preferably, it is in the range of 1.0 to 5.0.

The catalyst solution prepared in this way is particularly unstable against oxygen, moisture, etc., and may ignite or decompose and lose its activity. It is necessary to handle the product under an inert gas atmosphere such as inside the room.

Moreover, the solid here refers to a solid that does not react with the wall of the polymerization vessel or the catalyst, and includes, for example, glass, film, metal, knitted fabric, and the like.

It refers to natural or synthetic leather, etc., and plate-shaped ones are particularly preferred.

As an example of the manufacturing procedure for the polyacetylene film of the present invention, first, a catalyst solution is applied onto the surface of the solid described above, and a liquid film of the catalyst solution is created on the solid surface.

Introduce acetylene. A film of acetylene polymer is obtained on the surface of the catalyst solution and on the solid surface.

The temperature during the above reaction can be any temperature between -100 to 150°C. At a low temperature such as -78°C, a highly elastic and stretchable cis-type is generated, and at a high temperature, a trans-type is generated.

The thickness of the film can be adjusted within a range of 1 to 1 mm or more by adjusting the acetylene pressure and reaction time, or by changing the number of polymerizations, the type of solvent, etc.

For example, the conductivity can be increased by adding (doping) an electron-accepting substance (rogen, Lewis acid, etc.) or an electron-donating substance (alkali metal, etc.) to the polyacetylene film obtained by such a method. can. However, since the acetylene polymer produced by the above polymerization method has a fibril structure, its bulk density is low, and even if treatments such as doping are applied, it is difficult to further improve the conductivity t. . The true density of polyacetylene is approximately 1.15 g/an', but the bulk density of the polyacetylene film obtained by the above method is 0.4~
It is about 0.5 g/cm', and the space occupation rate is also about 50% at most. Considering that the electrical conductivity of polyacetylene is rate-determined by conduction between fibrils, it is considered that the improvement in electrical conductivity is limited by the low space occupancy of the polyacetylene film.

Therefore, in order to use polyacetylene as a conductor or semiconductor, it is desirable to increase the bulk density as much as possible to facilitate contact between fibrils, thereby increasing the conductivity. Needs to be compressed. in this case,
The range of plastic compression is determined by the thickness of the film after compression (d
) to the thickness before pressurization (D) is defined as the degree of deformation (r), then in order to improve the stain conductivity, the degree of deformation r? 3.0>r>1. It is necessary to compress within the range of t, and the conductivity decreases at r23-0.

9 For example, when using semiconductivity, the range of deformation r is preferably 2.52 r > 1.1, more preferably 2.0≧r > 1.1, and when r > 2.5, It becomes unsuitable for use as a semiconductor. It is thought that the electrical properties improve with moderate pressure because the contact between fibrils increases, but if the degree of deformation is further increased (then the electrical properties deteriorate, probably because the conjugate system is broken).

The reason why the range of deformation is narrower when using semiconductivity than when improving conductivity is thought to be that compression tends to increase the trap density, which has a large effect on the properties of a semiconductor. Examples that utilize the semiconductor properties of acetylene polymer films include diodes, solar cells, and the like.

To pressurize, you can use any method that can pressurize and compress the film, such as a hydraulic press.Also, even if doping treatment is performed before pressurization, doping treatment may not be performed after pressurization. You can go either way.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Tetrabutoxytitanium (concentration:
0-38 mol/l) # triethylaluminum (1,64 mol/j) fi" and use this as a catalyst liquid. While keeping the container with this catalyst liquid coated on the wall at -78°C, acetylene A polyacetylene film is polymerized on the wall by introducing gas into the container.Then, this film is heated at 180°C in vacuum for 1 hour.
A trans-type polyacetylene film is obtained by carrying out thermal isomerization over a period of time. The conductivity of this trans-type polyacetylene film is about 101 (Ωcm). The conductivity at this time is assumed to be 1.

Table 1 shows the relationship between the degree of deformation (r) and the electrical conductivity (relative value) when plastically compressed. An improvement in electrical conductivity is seen up to around ry 2.3, but above that, the rate of increase in electrical conductivity decreases.

Table 1 Example 2 A trans-type polyacetylene film obtained in the same manner as in Example 1 was placed in a 10% methanol solution of hydrochloric acid. After plastically compressing this film using a hydraulic compressor, a 9-order diode was fabricated, and the relationship between the degree of deformation and the diode characteristics was investigated. This diode is a Schottky type diode obtained by depositing At on one side of a polyacetylene film and Au on the other side, and has a barrier at the interface between AJ and polyacetylene.

Here, polyacetylene film is used as a P-type semiconductor. In this element, when the Al electrode side is negative, the current flows easily in the forward direction.

Table 2 shows the forward current (
The relationship between the relative value (relative value) and the degree of deformation (r) is shown. A rapid increase in forward current is seen up to a degree of deformation of 1.2, but thereafter the rate of increase decreases, and conversely decreases to 30% of the value before deformation at r+m2.9.

Table 2 Example 3 htn of Schottky diode element in Example 2
If at is made sufficiently thin and light is transmitted through the interface between the Aj layer and the polyacetylene film, a photovoltaic force can be obtained. 6th
The table shows the relationship between the degree of polyacetylene field deformation and the photovoltaic current in this device, and is expressed as a relative value with the photovoltaic current of the device made of a polyacetylene film that has not been compressed under pressure as 1. The photoelectromotive current increases due to compression up to the degree of deformation (r) = 1.2, but when it is further compressed, the electromotive current decreases rapidly, and at r = 2.9, the current decreases to 7% of the value before compression. .

Therefore, in order to fabricate a solar cell using polyacetylene film as a semiconductor, the degree of deformation r is 2.52 r
> 1.1, particularly preferably 2.0≧r > 1.1, where the effect of plastic compression is large.

Table 3 Patent applicant: Toshi Co., Ltd. 118-

Claims (1)

[Claims] (1) A method for producing an acetylene polymer film with excellent electrical properties, which comprises plastically deforming the acetylene polymer film under pressure so as to satisfy the following formula. 1,1 (r (5,0) (where r is the ratio of the thickness of the acetylene polymer film before pressurization to the thickness of the acetylene polymer film after pressurization).