JPH04125915A - Manufacture of dielectric composition and capacitor using same - Google Patents

Abstract

PURPOSE:To manufacture film type polymer dielectric material of high resistance, by a method wherein polymerizable monomer is subjected to electrolysis polymerization in the solution containing solvent containing supporting electrolyte and dopant-soluble plasticizer, and then electrolysis reduction is performed. CONSTITUTION:Nitrobenzene solution containing thiophene, perchloric acid tetra-n-butyl ammonium, and solvent di(2-ethylhexyl) phthalate is contained in a glass vessel and kept at about 5 deg.C. Electrolysis oxidation polymerization is performed for about 30 seconds by using ITO glass electrodes. Subsequently, the polarity is inverted and electrolysis reduction is performed for about one minute. After that, by methanol washing and vacuum drying, a polythiophene film of about 200nm in thickness is obtained on the surface of the ITO glass electrode. Thereby a thin film can be easily formed. When said film is used as a film capacitor, it can be utilized as a capacitor having high dielectric breakdown strength and large capacitance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a polymeric dielectric material and a capacitor using the same. In particular, the present invention relates to a method for producing a polymeric dielectric material made of a π-electron conjugated organic polymer and a capacitor using the same.

[Prior Art] It is known that a dielectric composition can be obtained by electrolytically polymerizing a five-membered heterocyclic compound such as thiophene or pyrrole and then electrolytically reducing the compound.

(Mol, Cr7sL Lig, Cr7sf, 8
3. 253 (19g2)).

The polymer film deposited and formed on the electrode by these electrolytic polymerizations has a thickness of, for example, 6000 angstroms (600 nm).
) The following very thin films can be formed, so if these thin films can be used as the dielectric layer of a capacitor, for example, the capacitance of the capacitor is inversely proportional to the thickness of the dielectric used, making it extremely advantageous for manufacturing capacitors with large capacitance. Become.

[Problems to be Solved by the Invention] However, in electrolytically polymerized products such as thiophene and pyrrole, during electrolytic polymerization, the anion components of the supporting electrolyte are similarly attracted to the electrode where the polymer is deposited, so these anions cannot be used as dopants. It is incorporated into the precipitated polymer. Therefore, in order to dedope these dopants, electrolytic reduction is carried out by reversing the direction of the electric field, but even after electrolytic reduction, some of the dopants remain in the polymer without being dedoped, resulting in the resulting electrolytic polymerization. The high molecular weight polymer obtained by the above method does not have a high resistance, and has a conductivity of about 10' S/cm, which has the disadvantage that it cannot be used as a dielectric material for capacitors that require high resistance.

The present invention provides a method for producing, by electrolytic polymerization, a high-resistance dielectric composition that can be effectively used as a dielectric without the above-mentioned drawbacks, and a capacitor using such a dielectric composition as a dielectric.

[Means for Solving the Problems] In order to solve the problems, the present invention has the following configuration.

(1) A method for producing a dielectric composition, which comprises electrolytically polymerizing a polymerizable monomer in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer, and then electrolytically reducing the monomer.

(2) The method for producing a dielectric composition according to item 1 above, wherein the plasticizer is a plasticizer containing at least one selected from phthalic esters, phosphoric esters, fatty acid esters, and polyesters.

(3) The method for producing a dielectric composition according to item 1 or 2 above, wherein the dopant is an ion with a radius smaller than that of the 5bF6- ion.

(4) A dielectric composition obtained by electrolytically polymerizing a polymerizable monomer in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer, and then electrolytically reducing it was used for the dielectric layer. Characteristic capacitors.

[Function] During electrolytic polymerization, a dissolving agent containing a dopant-soluble plasticizer is incorporated into the polymerized polymer, thereby increasing the plasticity of the polymer. Moreover, since the dopant is dissolved in the melting material layer containing the plasticizer, the mobility of the dopant increases and it becomes easier to be dedoped.

As a result, a dielectric composition that is easily dedoped by electrolytic reduction and therefore has high resistance is obtained.

In addition, since the polymer is deposited on the electrode by electrolytic polymerization, it is possible to easily obtain a thin film of the dielectric composition that cannot be obtained by ordinary melt molding, and capacitors using this for the dielectric layer are Capacity can be increased.

[Example] When a polymerizable monomer is electrolytically polymerized in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer,
As shown in FIG. 1, the polymer has a structure in which a dissolving material 2 containing a dopant-soluble plasticizer and an electronically conductive dopant 3 consisting of an anion component of the supporting electrolyte are dispersed in a polymer 1. The melting material 2 enters between the polymers 1.1 and the polymers 1.1.
The strong bond between the polymers 1 and 1 becomes a bond between the polymer 1 and the molecules of the dissolving material, and therefore the strong bond is loosened, and the dissolving material acts as if it were a lubricating oil between the polymers 1 and 1.

The dopant 3 is dissolved in the dissolving material layer formed between the polymers. In addition, since the polymer is surrounded by a dissolving material layer, when dedoping is performed by the electrochemical action of electrolytic reduction, the dopant comes out more easily than in conventional conductive polymer compositions.

The polymer 1 is an electropolymerized product of a polymerizable monomer, and the polymerizable monomer may be any monomer that can be electrolytically polymerized (5-membered heterocyclic compounds, aromatic compounds, etc. are generally used. Specific examples of monomers include are thiophene, pyrrole,
Typical examples include furan, benzene, aniline and their derivatives.

As the dissolving material 2, ordinary polymeric plasticizers, high boiling point solvents, or mixtures thereof are effective, and among them, phthalate ester, phosphoric ester, fatty acid ester, and polyester plasticizers are particularly effective.

Examples of phthalate ester plasticizers include di-2-ethylhexyl phthalate, dibutyl phthalate, dioctyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl lauryl phthalate, ditridecyl phthalate, and butylbenzyl phthalate.

Examples of the phosphoric ester plasticizer include tricresyl phosphate and trioctyl phosphate.

Examples of fatty acid ester plasticizers include propylene adipate, dioctyl adipate, dioctyl azelate, dioctyl sebacate, and methyl acetyl lysyllate.

For example, polyester plasticizers with a molecular weight of 1.0
A typical example is polyester having a molecular weight of about 0.000, but the molecular weight is not particularly limited to this, and it goes without saying that polyesters with different molecular weights may be used as necessary.

As dopant 3, the anion component of the supporting electrolyte used during electrolytic polymerization is doped into the produced polymer during electrolytic polymerization, but considering the mobility when dedoping by electrolytic reduction etc., the ionic radius is is preferably smaller, and more preferably smaller than at least 5bF6- ion.

Specifically, NO10gen (CIBr) is used as an electron acceptor.
-, I-), BF -C104So -1PF
-1AsF6-, 5bF6-, etc.

As the supporting electrolyte, an electrolyte containing the above dopant as an anion component is used, and the most typical one is a tetraalkylammonium salt. The number of carbon atoms in the alkyl group is usually 1 to 6, particularly preferably 1 to 4, such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, etc., and each of the four alkyl groups may be the same or different.

The solvent used in electrolytic polymerization is not particularly limited, and may be any solvent that dissolves the monomer that is commonly used in electrolytic polymerization.

Although it varies depending on the monomer used, examples thereof include nitrobenzene, propylene carbonate, and acetonitrile.

The conditions for electrolytic polymerization vary depending on the type and scale of the polymerization apparatus used, but usually the current density is 0.
A range of 5 to 10 mA,/cm'' is preferably used.

The thickness of the electrolytic polymer film produced on the electrode can be easily controlled by the current density and current application time, and the larger the value of the product of the two, the greater the amount of polymer produced. Therefore, since the polymerization time varies depending on the purpose, it cannot be generally specified, but the necessary conditions can be easily set by simple experiments.

The conditions for electrolytic reduction also vary depending on the conditions mentioned above, the type of melting material used, the type of dopant incorporated into the polymer, etc., but the current density is usually 0.5 to 1.
A range of 0 mA/cm2 is preferably used.

Next, the present invention will be explained using specific examples.

Example 1 300ml of nitrobenzene solution containing 0.2M of thiophene, 0.02M of tetra-n-butylammonium perchlorate, and 0.2M of di-2-ethylhexyl phthalate as a dissolving agent.
1 was placed in a glass container and kept at 5°C, and electrolytically oxidized and polymerized using an ITO (indium oxide/tin oxide) glass electrode (50 x 70 mm) at 2 mA/cm2 for 30 seconds, followed by reversing the polarity and increasing the temperature at 2 mA/cm2. Electrolytic reduction was carried out for 1 minute.

Thereafter, it was washed with methanol and dried under vacuum to obtain a polythiophene film with a thickness of about 200 nm on the surface of the ITO glass electrode. A gold vapor-deposited electrode with a diameter of 10 mm was formed on this film, and the conductivity in the thickness direction of the film was measured between it and the ITO electrode. The results are summarized in Table 1.

Example 2 Pyrrole 0.2M, hexafluoroantimony tetra-n-butylammonium salt 0.02M.

The same experiment as in Example 1 was carried out using a propylene carbonate solution containing 0.2 M of tricresyl phosphate as a dissolving material, and IT
A polypyrrole film with a thickness of about 200 nm was obtained on the surface of the O glass electrode. The conductivity in the thickness direction was measured in the same manner as in Example 1.

Example 3 The same experiment as in Example 1 was carried out using an acetonitrile solution containing 0.2 M of furan, 50.02 M of tetra-n-butylammonylam fluoroborey, and 0.2 M of propylene adipate as a dissolving material. Approximately 200
A polyfuran film of nm size was obtained. The conductivity in the thickness direction was measured in the same manner as in Example 1.

Example 4 The same experiment as in Example 1 was conducted using 3-hexylthiophene instead of thiophene.

Approximately 200 nm thick poly-3- on the surface of the ITO glass electrode.
A hexylthiophene film was obtained. The conductivity in the thickness direction was measured in the same manner as in Example 1.

Example 5 The same experiment as in Example 2 was carried out using 3-butylpyrrole instead of pyrrole.

Approximately 200 nm thick poly-3- on the surface of the ITO glass electrode.
A butylpyrrole film was obtained. The conductivity in the thickness direction was measured in the same manner as in Example 1.

Example 6 Example 3 using 3-ethylfuran instead of furan
I did the same experiment.

Approximately 200 nm thick poly-3- on the surface of the ITO glass electrode.
An ethylfuran film was obtained. The conductivity in the thickness direction was measured in the same manner as in Example 1.

Comparative Example 1 The same experiment as in Example 1 was conducted using a solution that did not contain the dissolving agent di-2-ethylhexyl phthalate.

Comparative Example 2 The same experiment as in Example 2 was conducted using a solution that did not contain di-2-ethylhexyl phthalate.

Comparative Example 3 In Example 3, the same experiment as in Example 3 was conducted using a solution that did not contain propylene adipate.

The electrical conductivity of the samples of Examples 1 to 6 and Comparative Examples 1 to 3 was measured by a two-terminal method. The results are shown in Table 1.

Table 1 As is clear from Table 1, in the comparative example, 1O-8S/
Although only a dielectric composition of about cm was obtained, the polymerizable monomer was electrolytically polymerized in a solution containing a dissolving agent containing the supporting electrolyte and a dopant-soluble plasticizer of the example of the present invention, and then electrolytically polymerized. By reducing 10”S/
It can be seen that a dielectric composition having a conductivity of less than cm can be manufactured.

Example 7 In Example 1, instead of the ITO glass electrode, a thickness of 10
0 μm aluminum foil (100 mm x 100 mm) was used. Aluminum was deposited on the obtained dielectric composition (thickness: about 200 nm) for electrodes. This sample is 5mm x 15
Cut it to mm, fold it over and attach the lead wire to the image electrode.
We prototyped a film capacitor element.

Example 8 In Example 2, instead of the ITO glass electrode, a thickness of 10
Using a 0 μm aluminum foil (100 mm x 100 mm), a dielectric composition (approximately 200 nm thick
We prototyped a film capacitor using m).

Example 9 In Example 3, instead of the ITO glass electrode, a thickness of 10
A dielectric composition (approximately 200 nm thick) was prepared in the same manner as in Example 7 using 0 μm aluminum foil (100 mm x 100 mm).
We prototyped a film capacitor using

When the dielectric breakdown strength of the capacitors of Examples 7 to 9 was measured, the sample of Example 7 had 50 to 80 kV/mm,
The sample of Example 8 is 45-70, and the sample of Example 9 is 40-70.
It showed excellent insulation properties at 65 kV/mm.

[Effects of the Invention] As explained above, according to the present invention, a polymerizable monomer is electrolytically polymerized in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer, and then electrolytically reduced. The excellent effect of easily obtaining a high-resistance dielectric composition in the form of a film can be achieved.

In addition, since the dielectric composition obtained in the present invention has high resistance and can be easily formed into a thin film, when used as a film capacitor, it has excellent dielectric breakdown strength and is easy to increase capacitance. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a conceptual cross-sectional view showing an example of a polymer composition obtained by electrolytic polymerization of the present invention before electrolytic reduction in the method for producing a dielectric composition. 1...Polymer, 2...Dissolving material, 3...Dopant Figure 1 3...Dopant procedure amendment 111F dynamic type) % formula% 2. Name of invention Address 1006 Kadoma, Kadoma City, Osaka Prefecture Name (58
2) Matsushita Electric Industrial Co., Ltd. Address: 210 Nishitenma Building, 4-9-2 Nishima, Kita-ku, Osaka 530 Name (9555) Patent Attorney Hiroyuki Ikeuchi (Telephone number 06-361-9334) 5. Amendment Order Date: January 22, 1991 (date of postponement of procedural amendment order) 6. “Detailed explanation of the invention” column of the specification to be amended 7. Lines 1 and 2 of page 2 of the specification of the contents of the amendment Insert the following item between lines. "3. Detailed explanation of the invention"

Claims (1)

[Scope of Claims] (1) A dielectric composition characterized in that a polymerizable monomer is electrolytically polymerized in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer, and then electrolytically reduced. Production method. (2) The method for producing a dielectric composition according to claim 1, wherein the plasticizer is a plasticizer containing at least one selected from phthalic esters, phosphoric esters, fatty acid esters, and polyesters. (3) The method for producing a dielectric composition according to claim 1 or 2, wherein the dopant comprises an ion having a radius smaller than that of the SbF_6^^ ion. (4) A dielectric composition obtained by electrolytically polymerizing a polymerizable monomer in a solution containing a dissolving material containing a supporting electrolyte and a dopant-soluble plasticizer, and then electrolytically reducing it was used for the dielectric layer. Characteristic capacitors.