JP2650777B2 - Method for producing polyaniline - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing polyaniline useful as a color-forming electrode of an electrochromic display element.

[Prior art] When depositing polyaniline on a metal electrode such as platinum or gold, it is relatively easy to obtain a uniform film,
In the case of depositing polyaniline on a transparent conductive film such as an ITO film or a NESA film, it is possible to adhere at a concentration of about 1 mol / each of the aniline monomer and the acidic aqueous solution.
It is difficult to synthesize a polyaniline having a sufficient film thickness, and when polymerizing for a long time at a low concentration, polyaniline is pulverized and deposited on the transparent conductive film, and it is difficult to obtain a uniform film. Met. Further, when the concentration is further increased, there is a problem that the polymerized polyaniline dissolves in the electrolytic solution and peels off.

[Object of the Invention] The present invention has been made in view of the above points,
An object of the present invention is to provide a method for producing a polyaniline film having a uniform and strong adhesive force on a transparent conductive film where uniform film formation is difficult.

[Means for Solving the Problems] In the present invention, a substrate on which a transparent conductive film is formed is immersed in an electrolytic solution obtained by mixing an aniline monomer and an acidic aqueous solution, and the substrate is used as one electrode by electrolytic oxidation polymerization. In the method for producing boraniline on the transparent conductive film, first,
The aniline monomer concentration is in the range of 0.1-1.0 mol /, the concentration of the acidic aqueous solution is in the range of 0.1-1.0 mol /, and the current density is 10
Under the condition of μA / cm ² -1 mA / cm ² , 100-700 ポ リ of polyaniline is subjected to electrolytic oxidation polymerization, and then the concentration of the acidic aqueous solution is adjusted to 0.1-
1.0 mol / range, aniline monomer concentration 0.1-1.
It is characterized in that electrolytic oxidative polymerization is further performed with an electrolytic solution having a range of 0 mol /.

[Operation] The present inventors have found that it is difficult to produce a uniform film of 1,000 mm or more on a transparent conductive film by a single electrolytic oxidation polymerization. The present invention has been accomplished by paying attention to performing the method.

That is, first, the aniline monomer concentration is in the range of 0.1 to 1.0 mol /, the concentration of the acidic aqueous solution is in the range of 0.1 to 1.0 mol /, and the current density is 10 μA / cm ^{2 to 1} mA / cm ^2.
In this method, polyaniline of 00% is subjected to electrolytic oxidation polymerization. At this time, if the aniline monomer concentration is less than this range, it is difficult to obtain a good polyaniline film, and it takes too much time for polymerization.If the aniline monomer concentration is more than this range, the aniline monomer is difficult to dissolve in the electrolytic solution. There are difficulties. If the concentration of the acidic aqueous solution is smaller than this range, the electric resistance of the electrolytic solution increases, and the potential of the anode on which the polyaniline is formed increases, so that polyaniline may be decomposed. May be dissolved. If the current density is less than this range, it takes too much time for polymerization,
If it is larger than this range, it is difficult to polymerize a uniform film.

When the film thickness is smaller than 100 °, it is difficult to control the film thickness. When the film thickness is larger than 700 °, the nonuniformity of the film thickness is gradually increased.

Under such conditions, the electrodeposition time is set to 10 minutes or less, electrolytic polymerization is performed, and when washed, polyniarin having a weak surface adhesion is dropped, and as a result, a relatively uniform polyaniline film having a thickness of 100 to 700 mm is produced. Filmed.

Next, the concentration of the acidic aqueous solution is in the range of 0.1 to 1.0 mol /,
When electrolytic oxidation polymerization is carried out using an electrolytic solution having an aniline monomer concentration in the range of 0.1 to 1.0 mol /, a uniform polyaniline film of 1,000 to 5,000 mm can be formed by appropriately selecting the current density and the electrodeposition time. You can do it.

This is because polyaniline having a film thickness that can be formed by the first electrolytic oxidation polymerization is polymerized, so that the polyaniline film easily adheres during the second electrolytic oxidation polymerization. The variation in surface resistance due to the surface irregularities of the polymerized polyaniline film is much smaller than the variation in surface resistance due to the surface irregularities of the transparent conductive film. Is likely to be maintained.

[Examples] Hereinafter, examples of the present invention will be described in detail along with comparative examples.

Example 1 A 40 mm square glass plate, a platinum plate, and a saturated calomel electrode with an ITO film coating were placed on an anode, a cathode, and a reference electrode, respectively, in an electrolytic bath containing an electrolyte containing a mixture of aniline 0.1 mol / and sulfuric acid 0.1 mol /. And connected to a DC power supply.

In such a state, it is confirmed that the anode potential is initially about 0.85 V or more at the reference electrode by a DC power supply, and a current density of 100 μA / cm ² (constant current) is applied for 5 minutes to deposit the polyaniline film on the ITO. Polymerized on the membrane. Thereafter, when the glass plate was taken out of the electrolytic cell and washed with water, the polyaniline having a weak adhesive force on the surface layer was dropped, and a 200-mm-thick polyaniline film was formed on the ITO film.

Next, this glass plate was treated with 0.5 mol of aniline / 0.5 mol of sulfuric acid.
Immersed together with a saturated calomel electrode and a reference electrode in an electrolytic cell containing a mixture of
Electric current was applied at 100 μA / cm ² for 10 minutes to polymerize the polyaniline film.

The polyaniline film thus obtained was of good quality and excellent in uniformity of 2,400 mm.

Example 1 'An example in which the polyaniline obtained in Example 1 is applied to an electrochromic device will be described.

And glass substrates 3mm thick obtained in Example 1, 3mm was thick with a transparent conductive film on a glass plate coloring layer WO ₃ formed in the opposite substrate, and after sealing the periphery, as an electrolyte A propylene carbonate solution containing 1 molar lithium perchlorate was charged.

When a DC voltage of 1.0 V was applied to the thus obtained electrochromic device using polyaniline as an anode and WO ₃ as a cathode, both polyaniline and WO ₃ were colored blue, and the visible light transmittance was 10.5%. When a DC voltage of 0.5 V was applied using WO ₃ as an anode and polyaniline as a cathode, both polyaniline and WO ₃ were decolorized.
The visible light transmittance was 55%, indicating good light transmittance.

It was confirmed that the polyaniline film exhibited excellent electrochromism without being peeled off even after repeating the discoloration about 2,000 times, and without causing color unevenness upon coloring. Also, during this period, when a constant voltage was applied to the electrochromic element, the fluctuation of the density was extremely small and a constant density was obtained, so that stable driving could be performed.

This is because polyaniline is uniformly polymerized on the ITO film,
This indicates that the adhesive force is also strong.

Comparative Example A 40 mm square glass plate, a platinum plate, and a saturated calomel electrode of an ITO film coating were used as an anode, a cathode, and a reference electrode, respectively, in an electrolytic tank containing an electrolyte mixed with 0.5 mol / of aniline and 0.5 mol / of sulfuric acid. Immersion, current density 100μA / cm ²
(Positive current) for 30 minutes to polymerize the polyaniline film and rinse it with water, the polyaniline film flows out, the film pressure falls below 100 °, and the uniformity is impaired.
It was not practical.

Example 2 Polyaniline was polymerized under the same conditions as in Example 1 except that a 70 mm square ITO film-coated glass plate was used as an anode, the second sulfuric acid concentration was 0.1 mol /, and the energizing time was 20 minutes.

The polyaniline film thus obtained has a thickness of 3,500.
Å was a uniform film.

Example 3 Polyaniline was prepared under the same conditions as in Example 1 except that a 70 mm square ITO-coated glass plate was used as an anode, the second sulfuric acid concentration was 0.5 mol /, the current density was 500 μA / cm ² , and the energizing time was 4 minutes. Was polymerized.

The polyaniline film thus obtained had a thickness of 4,500.
Å was a uniform film.

Example 4 Using a 70 mm square ITO film-coated glass plate as an anode, the second aniline concentration was 0.1 mol /, the sulfuric acid concentration was 0.1 mol /,
Polyallinine was synthesized under the same conditions as in Example 1 except that the energization time was changed to 10 minutes.

The polyaniline film thus obtained has a thickness of 2,400.
Å was a uniform film.

Example 5 The first aniline concentration was 0.3 mol / and the sulfuric acid concentration was 0.5
Mol /, current density 500 μA / cm ² (constant current), energizing time 3 minutes, the second aniline concentration 0.3 mol /,
Polyaniline was polymerized under the same conditions as in Example 1 except that the sulfuric acid concentration was 0.5 mol / hour and the energizing time was 5 minutes.

The polyaniline film thus obtained has a thickness of 1,500.
Å was a uniform film.

The thickness of the polyaniline obtained by the first electrolytic polymerization was 600 °.

Example 6 The first aniline concentration was 0.5 mol /, and the sulfuric acid concentration was 0.5
Mol /, the current density was 50 μA / cm ² (constant current), the energization time was 10 minutes, and the second aniline concentration was 0.3 mol /
Polyaniline was polymerized under the same conditions as in Example 1 except that the sulfuric acid concentration was 0.5 mol / hour and the energizing time was 5 minutes.

The polyaniline film thus obtained has a thickness of 2,400.
Å was a uniform film.

The thickness of the polyaniline obtained by the first electrolytic polymerization was 200 °.

Example 7 A 40 mm square glass plate, a platinum plate, and a saturated calomel electrode each coated with an ITO film were placed in an electrolytic cell containing an electrolytic solution containing 0.1 mol / of aniline and 0.2 mol / of HBF ₄ as an anode, a cathode and a reference, respectively. Immerse as an electrode, current density 50μA / cm
² Apply a current (constant current) for 5 minutes to polymerize the polyaniline film. After washing with water, the glass plate was treated with 0.5 mol / ml of aniline and H
A saturated calomel electrode and a reference electrode were immersed in an electrolytic tank containing a mixture of 1.0 mol / BF ₄ as an electrolytic solution, and a current density of 1.0 mA / cm ² was supplied for 5 minutes to polymerize the polyaniline film. The polyallynin film obtained in this way is 4500
Å was of good quality and excellent in uniformity.

The preferred embodiment has been described above, but the present invention is not limited to this, and various applications are possible.

Acids used as the acidic aqueous solution include inorganic acids such as perchloric acid and hydrochloric acid in addition to sulfuric acid and HBF ₄ (boron tetrafluoride).
Species or a combination of two or more can be used.

Also, when sulfuric acid is used as the acidic aqueous solution, the aniline monomer concentration and the sulfuric acid concentration at the time of the first electrolytic polymerization are 0.
The concentration may be appropriately selected within the range of 1 to 1.0 mol /, and it has been confirmed that, particularly when the sulfuric acid concentration is x mol /, the aniline monomer concentration should be (0.1x + 0.05) mol / or more. Sulfuric acid is ionized in the electrolytic solution and conducts electricity by these ions.If the sulfuric acid concentration is high, the resistance of the electrolytic solution decreases, and the anodic potential decreases. When the potential is lower than about 0.85V, polyaniline cannot be polymerized. However, even if the sulfuric acid concentration is high, when the concentration of the aniline monomer increases, the aniline monomer hinders the movement of ions (hydrogen ions, sulfate ions) in the electrolytic solution, so that the resistance of the electrolytic solution increases and, at the same time, the anode potential And the synthesis of polyaniline becomes possible.

[Effects of the Invention] According to the present invention, polyaniline is synthesized and formed on a transparent conductive film such as an ITO film or a NESA film, which was conventionally difficult, by performing electrolytic oxidation polymerization twice under specific conditions. Can be used as various kinds of electronic materials such as auxiliary electrodes of an electrochromic element, as well as being particularly suitable as an electrochromic material because of its uniform thickness and strong adhesion. It is.

Continuation of front page (56) References JP-A-60-253021 (JP, A) JP-A-2-79047 (JP, A) JP-A-57-11810 (JP, A) JP-A-57-145019 (JP) , A) JP-A-60-91528 (JP, A) JP-B-5-16364 (JP, B2)

Claims (1)

(57) [Claims] 1. A substrate on which a transparent conductive film is formed is immersed in an electrolytic solution in which an aniline monomer and an acidic aqueous solution are mixed, and boraniline is produced on the transparent conductive film by electrolytic oxidation polymerization using the substrate as one electrode. In the method, first,
The aniline monomer concentration is in the range of 0.1-1.0 mol /, the concentration of the acidic aqueous solution is in the range of 0.1-1.0 mol /, and the current density is 10
Under the condition of μA / cm ² -1 mA / cm ² , 100-700 ポ リ of polyaniline is subjected to electrolytic oxidation polymerization, and then the concentration of the acidic aqueous solution is adjusted to 0.1-
1.0 mol / range, aniline monomer concentration 0.1-1.
A method for producing polyaniline, wherein electrolytic oxidation polymerization is further performed with an electrolytic solution having a range of 0 mol /.