JPS61126158A - Acetylene polymer having improved oxidation stability and production thereof - Google Patents

Abstract

PURPOSE:To improve oxidation stability without detriment to characteristics inherent in acetylene polymer, by treating an acetylene polymer with fluorine gas at low concn. CONSTITUTION:An acetylene polymer is treated in a fluorine gas atmosphere under fluorine partial pressure of 20mmHg (pref. the remainder being helium gas). By this treatment, 0.1-10mol% of fluorine per mol of CH repeating unit of acetylene polymer is introduced into the acetylene polymer. Pref. this treatment in the fluorine gas atmosphere is carried out at 30 deg.C or below. The treating time is pref. 10min to 20hr from the viewpoint of workability. The resulting acetylene polymer contg. a small quantity of fluorine may be used as such. Alternatively, the polymer is doped with a donor or an acceptor to bring its electrical conductivity into a desired value, and processed to use it as a material for electrical and electronic elements.

Description

[Detailed description of the invention] [Industrial application field] The present invention provides acetylene q' with improved oxidative stability. Polymers and their manufacturing methods.

[Conventional technology]

Acetylene polymers are useful as electrical/electronic device materials because of their electrical conductivity in the semiconductor region 1c.

In particular, the acetylene polymer is
, Bc13, BB r3, SOs, etc. or to Na%, Li.

By treating with an electron-donating compound (donor) such as ammonia, the stain conductivity can be easily controlled over a wide range, and it is expected to have various uses as an electrically conductive material.

However, such useful acetylene polymers have the disadvantage of being easily oxidized and deteriorated by oxygen, and not only do they require a great deal of effort to handle, but their durability as a material is limited. It had the disadvantage of lacking in.

Heretofore, attempts have often been made to improve the oxidative stability of acetylene polymers. For example, there is a method to improve the oxidation stability of acetylene polymers by implanting fluorine ions (F”) t-ions into the polymers.
, Phys, Chea] 982, Dan, 3364-336
7.

Furthermore, JP-A-58-42625 proposes a method of improving the oxidative stability of an acetylene polymer by coating the surface thereof with an antioxidant effect.

[Problem that the invention seeks to solve]

However, in the case of acetylene polymers treated by the former method of implanting fluorine ions, the F+ ion introduced region is limited to only the surface layer of the film, and the reaction is non-equilibrium.
Overall, the effect of oxidation stability is not sufficient. In addition, it is generally known that ion implantation causes a large amount of radiation damage.
(1984)), surface modification techniques by ion implantation have problems specific to high-energy beams. Moreover, this method requires very expensive equipment, and therefore is not economically preferred for the following reasons. The acetylene polymer coated with toluene or the like is used in this method, and the dopant and the acetylene polymer can be brought into contact with each other by a conductor, which is one of the practical uses of the acetylene polymer. This is because they are hindered.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an acetylene polymer which has further improved oxidation stability without degrading the inherent properties of the acetylene polymer. Another object of the present invention is to provide an efficient process for preparing the acetylene polymers with improved oxidative stability.

[Means for solving problems]

The present inventors conducted extensive research in view of the above objectives, and found that
The present invention was achieved by recognizing that acetylene polymers treated with extremely low concentration of fluorine gas have significantly improved oxidation stability.

That is, the present invention provides an acetylene polymer and a fluorine gas in which the fluorine content based on fluorine gas treatment is 0.141v% or more and 10-f:/I/% or less of CH repeating units of the acetylene polymer. An acetylene polymer is left in a fluorine gas atmosphere with a partial pressure of 20+mHg or less, and 90.1 moA per mole of CH repeating unit of the acetylene polymer.
This is a method for producing an acetylene polymer with improved oxidation stability, characterized by containing fluorine in the acetylene polymer in an amount of 96 to 107 p%.

The acetylene polymer used in the present invention is a polymer in which the conjugated system extends to such an extent that the electrical conductivity increases by two or more fingers when doped with iodine. The obtained acetylene polymer is used as it is, or after pretreatment such as various doping or secondary processing into a desired form. Furthermore, any shape such as powder, fiber, film, gel, or lump can be used.

In the present invention, it is important that the treating agent for the acetylene polymer is fluorine gas (F2). In the present invention, the fluorine content in the acetylene polymer based on the fluorine gas treatment is 0.1 per mole of CH repeating unit of the acetylene polymer. It is important to maintain a relatively small amount in the range of ~10 mol%. If the fluorine content is not within this range, a sufficient oxidation stabilizing effect cannot be obtained. The fluorine content is 10 mol%
When it becomes larger than
The inherent properties of the acetylene polymer are degraded. In general, the fluorine content that provides a favorable oxidation stabilizing effect is 1
~67~%.

In the present invention, as a method for incorporating fluorine into the acetylene polymer based on fluorine treatment, there is a method of leaving the acetylene polymer in a fluorine gas atmosphere.
If an acetylene polymer is left in a fluorine gas atmosphere of InHg or higher, it will contain a large amount of fluorine (20 mol % or more per 17 μm of CH repeating unit of the acetylene polymer) even for a very short time. In order to make the acetylene polymer contain a low amount of fluorine as specified in the present invention, it is preferable to leave the acetylene polymer in an atmosphere of extremely low concentration of fluorine gas.

According to the research conducted by the present inventors, it was found that the oxidative stability of acetylene polymers was also affected by the treatment conditions of fluorine gas.2 In other words, treating acetylene polymers with fluorine gas under milder conditions further improved Excellent oxidation stability is obtained.

Generally, the fluorine gas partial pressure is 20 mHg or less, preferably 0.
Keep it within the range of 1 to 10 mHg, especially 0.2 to 5 mHH8
The treatment is preferably carried out at a temperature of 0°C or lower, preferably 30°C or lower. The processing time is selected from 10 minutes to 20 hours in consideration of workability. The fluorine content is controlled by adjusting the partial pressure of fluorine gas, treatment temperature, and treatment time. If the fluorine gas partial pressure is higher than the above range, it is possible to obtain an acetylene polymer with the desired content by extremely shortening the treatment time, but in general, such operating conditions not only have poor workability but also The oxidative stability of the obtained acetylene polymer is also poor. Similar drawbacks may also occur if the processing temperature is high.

Any method can be used to obtain a low partial pressure atmosphere of fluorine gas, such as directly introducing fluorine gas into the vacuum system to the desired partial pressure, but it is easier to dilute the fluorine gas in several portions with helium gas. It's good because it's easy.

After reaching the desired fluorine content, excess fluorine gas is removed by a method such as vacuum evacuation. Acetylene polymers with improved oxidative stabilization effects are obtained without sacrificing the useful properties of the acetylene polymers.

The acetylene polymer containing a small amount of fluorine obtained by the above method may be used as it is or may be subjected to necessary post-processing after adding various donors and acceptors to achieve the desired electrical conductivity. Not only is it useful as a variety of electrical and electronic devices, but it is also very useful as a positive electrode active material for lithium batteries, an electrode active material for secondary batteries, and a solar cell material. Furthermore, the acetylene polymer obtained by the method of the present invention can be made into P-type or n-type by the subsequent doping treatment.
It can be made into a type of semiconductor. And P-type semiconductor and n
It is also possible to easily create a pn junction by combining it with a type semiconductor.

[Effect]

It has been revealed that acetylene polymers are aggregates of fibrils with a diameter of approximately zooA (J, Poly
m, Sei, Polym, Chem, Ed.
I 2.11 (1974)). There are many voids between the fibrils, and the bulk density is only about 1/2 of the true density. This structure of the acetylene polymer is extremely suitable for homogeneous adsorption of gaseous doping agents.

〔Example〕 The present invention will be explained in more detail by way of Examples below.

Reference Example 1 [Synthesis of acetylene polymer film] 3.4 ml (1
After adding 0-0 mmol lv of titanium tetrabutoxide and cooling to -78°C, 3.8,1/
(28.1 mm/I/) of triethylaluminum was added to react. The catalyst solution was aged by leaving the reaction vessel at room temperature for 1 hour. The reaction vessel was then cooled with dry ice-methanol cryogen.
The system was cooled to ℃ and the high purity argon gas in the system was evacuated using a vacuum cylinder.

After shaking the reaction vessel strongly to make the catalyst solution adhere uniformly to the inner wall of the reaction vessel, purified acetylene gas at a pressure of 1 atm was immediately introduced while keeping the reaction vessel at a temperature of -78°C and stationary. Polymerization was started. Simultaneously with the initiation of polymerization, an acetylene polymer with metallic luster was deposited on the inner wall of the reaction vessel. Thereafter, polymerization was carried out for 10 minutes while maintaining the acetylene pressure at about 1 atm, and then unreacted acetylene was evacuated with a vacuum pump to stop the polymerization.

After removing the residual catalyst solution with a syringe under a high-purity argon atmosphere, washing was repeated 20 times with 30 μm of purified toene, and then vacuum drying was performed at room temperature.

The part where the catalyst solution adhered to the inner wall of the glass reactor has an area equal to that part and a thickness of 150 μm and a cis content of 98
% acetylene polymer film was obtained.

The electrical conductivity of this acetylene polymer film was measured by attaching electrodes to the front and back surfaces of the acetylene polymer film by steaming metallic gold. The electrical conductivity was 1X10Q at a temperature of 25°C.

Example! [Fluorine treatment] The width of the acetylene polymer film synthesized in Reference Example 1 was 3C.
A small piece with a length of 5 CIK was cut out. The weight of this piece was 0.1229g.

The small piece was placed in a closed reaction container, and the inside of the container was evacuated using a vacuum bonder, and then helium gas was introduced into the container to a pressure of 1 atmosphere, and then further evacuated using a vacuum bonder. This operation was repeated three times to wash the acetylene polymer membrane. After evacuating the inside of the container, 0.05 mol% (99.95 mol/I/% helium) fluorine gas (fluorine gas partial pressure 0.38 mHg) was prepared in advance.
and left at room temperature for 5 hours.

After 5 hours of fluorine treatment, the interior of the reaction vessel was sufficiently replaced with helium gas. When the acetylene polymer film was taken out, its weight had increased by 0.1271yK. The amount of fluorine introduced into the acetylene polymer film calculated from this weight increase was 2.3 mol % per mol of CH repeating unit of the acetylene polymer, and this was also confirmed from the results of elemental analysis. Further, the electrical conductivity of this film was measured by vapor depositing metal gold on both the front and M sides of the acetylene polymer film and attaching electrodes, and it was measured at 25°C using a lXl0Ω equipment.

The surface reflection infrared spectrum of this film was measured and the results are shown in FIG. 14001.1330C1 by fluorine treatment
A new peak due to fluorine appeared at 1 and 900aR.

Acetylene polymer films with various fluorine contents were obtained in the same manner as above except that the fluorine concentration and fluorine treatment time were changed. The results are also shown in Table IK.

[Oxidation stability test]

Experiments on the oxidation stability of the acetylene polymer membranes treated with fluorine at various concentrations obtained above were conducted as follows. The fluorine-treated acetylene polymer membrane was placed in a glass container, and after degassing and creating a vacuum, 1 atm of pure oxygen was introduced into the container.

After leaving the sample at a temperature of 25° C. for 14 or 20 hours, the sample was taken out and doped with iodine at room temperature, and the achieved electrical conductivity was measured. Note that the measurement of the achieved electrical conductivity was performed as follows. After placing the sample in a sealed glass container (vacuum fin) and evacuating the inside of the container to a degree of vacuum of I x 10 gHg or more, iodine vapor was introduced into the container.
Hg) The electrical conductivity of the iodine-doped sample after being left for a certain period of time was measured using the four-probe method. The time for leaving the sample in the iodine vapor atmosphere was set at a time when the ME gas conductivity reached saturation. The results are shown in Table 1.

Comparative Example 1 An experiment on the oxidation stability of the acetylene polymer membrane synthesized in Reference Example 1 (not subjected to fluorine treatment) was conducted under the same conditions as in Example 1. The results are also shown in Table 1.

The degree of oxidation stability of acetylene polymers can be compared by comparing the magnitude of the electrical conductivity achieved after oxidation in Table 1. For example, when doped with iodine, an acetylene polymer (Experiment No. 8) whose ultimate electrical conductivity increased to 240 ΩG was compared to an acetylene polymer whose electrical conductivity increased only to 20 Ωc/n (untreated acetylene electropolymer of Experiment No. 1). It has extremely good oxidation stability.

As shown in Table 1, when the fluorine content is within the range of the present invention, the acetylene polymer reaches the oxidation stability test! The degree of decrease in air wandering conductivity was small, and all exhibited excellent oxidation stability. It was also found that when the fluorine content exceeded 10 mol %, the electrical conductivity of the acetylene polymer reached by iodine was rapidly reduced, and the properties of the acetylene polymer itself were changed.

[Oxidation stability after iodine doping]

The acetylene polymer film having a fluorine content of Z 3 mole % obtained in Example 1 was subjected to iodine doping at room temperature for 1 hour, and then the sample was evacuated for an additional 3 hours to remove excess iodine. The obtained film is made of acetylene polymer CHjif.
i-return unit 1-1: doped with 10-T:/L/% iodine per A/. The electrical conductivity of this membrane is 290
After this sample was left in the air at a temperature of 25° C. and a humidity of 0% for 10 days, the electrical conductivity was measured by the four-probe method. The electrical conductivity at this time is 15
It was 0Ωα.

For comparison, the acetylene polymer membrane synthesized in Reference Example 1 (
(without fluorine treatment) were tested in the same manner as above. When doping with 10M/L'% iodine in the same manner as above, the electrical conductivity was 3000 cI+, but after being left in the air for 10 days under the same conditions as above, the electrical conductivity was 1000 cI+. It drops to a circle.

Usage Example 1 [Secondary Battery Experiment] Using the acetylene polymer membrane with a fluorine content of 2.37% obtained in Example 1, a battery was prototyped using the acetylene polymer membranes for both positive and negative electrodes. Two acetylene polymer membranes were placed on both poles via a glass filter. The electrolytic solution used was one in which 1N of lithium perchlorate was dissolved in propylene carbonate. Platinum mesh was used for both positive and negative electrodes for current collection. The acetylene polymer membrane used had an area of 1 cm x 1.5 an and a weight of 0.
It was 0.15g.

We measured the charge/discharge cycle characteristics of this secondary battery.
After performing LA constant current charging for 10 minutes (0.5 mol % doping), constant current discharging at 1 fiA was performed for 10 minutes. After the number of charge/discharge cycles exceeded 250, the charging voltage gradually increased.

For comparison, the acetylene polymer membrane synthesized in Reference Example 1 (
A secondary battery similar to the above was assembled (without fluorine treatment) and the number of charge/discharge cycles/L' was tested. After the number of charge/discharge cycles exceeded 120, the charging voltage gradually increased.

〔Effect of the invention〕

According to the present invention, an acetylene polymer with improved oxidative stability is provided without impairing the properties originally possessed by the acetylene polymer. Furthermore, the acetylene polymer of the present invention tends to be durable in terms of its oxidation stabilizing effect, and the effect does not easily deteriorate due to washing with organic solvents or various doping treatments. Furthermore, according to the present invention, the acetylene polymer can be produced very easily by a simple operation of treating a conventionally known acetylene polymer with low concentration fluorine gas. Furthermore, the acetylene polymer with improved oxidation stability obtained by the present invention can be handled in exactly the same manner as conventional acetylene polymers.

[Brief explanation of drawings]

FIG. 1 shows the surface reflection infrared absorption spectrum μ of the acetylene polymer of the present invention. Figure 1 (%) Wavenumbers

Claims (1)

[Scope of Claims] 1) An acetylene polymer characterized in that the fluorine content based on fluorine gas treatment is from 0.1 mol % to 10 mol % per mol of CH repeating unit of the acetylene polymer. 2) The acetylene polymer is left in a fluorine gas atmosphere with a fluorine gas partial pressure of 20 mmHg or less, and the acetylene polymer contains 0.1 mol% or more and 10 mol% or less of fluorine per mol of CH repeating unit of the acetylene polymer. A method for producing an acetylene polymer characterized by: