JP2002371124A - Method for producing electroconductive polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent method for producing at a low cost a transparent electroconductive material having excellent electroconductivity, transparency and stability, and suitable for an electronic circuit of a display. SOLUTION: A conjugated double bond is formed by an elimination reaction of a precursor polymer having a leaving group. The elimination reaction is started by a laser in the method for producing the electroconductive polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive polymer suitable for forming a transparent conductive circuit suitable for a display such as a liquid crystal display device, a plasma display and an organic EL. .

[0002]

2. Description of the Related Art Liquid crystal display devices, plasma displays,
A display such as an organic EL displays an image by electrically driving individual pixels and turning on and off light in each pixel. Various driving methods are known, such as an active matrix and a passive matrix. In any case, in order to perform driving, it is necessary to control a voltage or a current in each pixel, and it is necessary to construct a circuit for that. It is. In this circuit, a transparent conductive material that does not impair the display is used. As the transparent conductive material, I
TO is best known and has been used primarily. ITO
Is mainly formed as an ITO film on a substrate by sputtering, and is processed into a circuit by lithography using a photosensitive resin. Because sputtering is a vacuum process, it has low productivity and is therefore expensive. Similarly, lithography also uses expensive photosensitive resin, is a process with a large number of steps, and is expensive. The environmental load is also large. Furthermore, indium, which is a rare metal, is used for ITO, but indium has a low Clark number, and there is a risk of resource shortage.

[0003] In the information-oriented society, the display serving as a man-machine interface plays an extremely important role, and it is considered that its importance will increase in the future. For this reason, there is a strong demand for the development of a low-cost, low-impact alternative to ITO and a method of manufacturing the same.

[0004]

SUMMARY OF THE INVENTION Conducting polymers are IT
It is promising as an O substitute material. However, conventional methods for producing a conductive polymer cannot simultaneously satisfy practical conductivity, transparency, stability, workability, and the like. The present invention has been made based on such circumstances, and has an object to provide an excellent method for producing a transparent conductive material suitable for an electronic circuit of a display that is low in cost, and has excellent conductivity, transparency, and stability. Is what you do.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that in a method for producing a conductive polymer in which a conjugated double bond is generated by an elimination reaction of a precursor polymer having an elimination group, an elimination reaction is performed. It has been found that the problem can be solved by starting with a laser, and the present invention has been completed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The precursor polymer having a leaving group is not particularly limited as long as it forms a conductive polymer by forming a conjugated double bond by a leaving reaction, and the polymer described in US Pat. No. 3,706,677 is used. , Etc., may be initiated by heat. The general chemical structure of a preferred precursor polymer is represented by the following general formula (I).

[0007]

Embedded image Here, Ar is an aromatic ring such as phenylene or naphthylene, or a heteroaromatic ring, and these may have a substituent on the ring, and L is a substituent which is eliminated together with hydrogen by laser light. The polymerization degree n is usually in the range of 5 to 100,000, preferably 10 to 50,000. If the degree of polymerization is low, the conductivity tends to be low, and if it is too high, problems tend to occur due to solubility in a solvent, and workability tends to be poor. Examples (a) to (d) of more preferred precursor polymers are shown below together with the equations of the respective elimination reactions. These precursor polymers are electrically insulative and soluble in solvents before the elimination reaction, and have a conjugated structure by the elimination reaction to improve conductivity and become insoluble in the solvent. And change.

[0008]

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[0009]

Embedded image R is an optionally substituted alkyl group such as methyl, ethyl, propyl or the like; or an optionally substituted aryl group such as phenyl or naphthyl; X ⁻ is Cl ⁻ , Br ⁻ ,
I ^-, PF ₆ ^-, such as, represents a counter anion residue, n represents the same as the general formula (I). Among the above-mentioned conductive polymers, those having an onium salt structure as a leaving group are preferred because of their excellent film-forming properties, and more preferred are the sulfonium salts as described in (a) above.

[0010] The precursor polymer having an onium salt structure may have various substituents, for example, an alkyl group, an alkoxy group, a cyano group, a halogen, a silyl group, etc., added to the aromatic ring or the vinyl structure. Further, the aromatic ring may be a heteroaromatic ring. If specifically shown, for example, a compound having the following structure can be mentioned.

[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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A method suitable for producing a conductive polymer using the precursor polymer exemplified above will be described below.
The precursor polymer is usually dissolved in a solvent and applied on a substrate. As the solvent, water, methanol, ethanol, DMF, THF, DMSO, N-methylpyrrolidone, acetone, or the like may be appropriately selected and used depending on the type of the precursor polymer, the use of the conductive polymer, and the like. it can. These solvents may be used as a mixture of two or more kinds. In the solvent, anionic, cationic, nonionic surfactants can also be used for improving the solubility, and further, a dopant for improving conductivity, or absorbing laser light and converting it to heat. It is also possible to use a light-to-heat conversion material in combination.

[0017] As the dopant, for example, p- toluenesulfonic acid, benzenesulfonic acid, anthraquinone sulfonic acid, naphthalene disulfonic acid, sulfonic acid and its alkali metal salts and the like, AsF _5, SbF ₅ fluoride such as metal, PF ₆ ^-, ClO ₄ ^- and the like anions, Na, K,
Alkali metal etc., halogens such as I _2, Br _2, TCNQ
And the like. When the dopant is used, the amount of the dopant is 0.01 to 0.1 to 1 unit (one double bond) of the conjugated system of the conductive polymer.
3 moles are preferred. If the amount is too small, the effect cannot be sufficiently obtained, and if it is too large, it does not contribute to improvement in conductivity.

The use of the photothermal conversion material for the laser is such that the substrate and the precursor polymer do not absorb the laser light,
This is particularly effective when sufficient heat generation cannot be obtained. Specific examples include carbon black, titanium black, iron black and other inorganic pigments, azo dyes, metal complex salt azo dyes,
Organic dyes such as phthalocyanine dyes, cyanine dyes, anthraquinone dyes, squarylium dyes and pyrylium dyes can be mentioned. When the light-to-heat conversion material is used, the amount used is 0.1 to 3 with respect to 100 parts by weight of the precursor polymer.
0 parts by weight is preferred. If the amount is too small, a sufficient effect cannot be obtained, and if it is too large, transparency tends to be lost. The solid content concentration of the precursor polymer in the solvent is 0.0
The content is preferably in the range of 1 to 30% by weight, preferably 0.05 to 2%.
The range is 5 wt%. If the concentration is too low, the conductivity is poor,
Conversely, if the concentration is too high, problems tend to occur in terms of transparency.

Since the conductive polymer of the present invention is generally transparent, it is preferable to use a transparent substrate as the substrate. The transparent substrate is preferably glass or plastic, and examples thereof include quartz glass, alkali-free glass, glass such as alkali glass, and plastic substrates such as PET, polycarbonate, polyether sulfone, and acrylic resin. When using a plastic substrate, use SiO
It is preferable that an oxygen barrier film such as 2 is formed thinly on the surface.

A known polymer coating solution such as a spin coater, a spray coater, a carton coater, a roll coater, a blade coater, a rod coater, a transfer roll coater, a dip coater, a kiss roll coater, a gravure coater, and a knife coater is applied to these substrates. Apply by means. After application, drying is preferably performed to remove the solvent. The drying method is not particularly limited, and examples thereof include a convection oven, a hot plate, and a hot-air alternating-current dryer. The drying temperature is usually 40 to 150 ° C., preferably,
50-100 ° C. If the drying temperature is too low, the solvent is not sufficiently removed, and it is difficult to obtain a high conductivity. On the other hand, if the drying temperature is too high, a desorption reaction proceeds, which may cause a problem in circuit formation processing. The drying time varies greatly depending on the drying method, but generally ranges from 20 seconds to 60 minutes. The preferred thickness after drying is in the range of 50 nm to 20 microns.

Next, the obtained film containing the precursor polymer is irradiated with a laser. As the laser light, a laser in which light is converted into heat in the precursor polymer film or on the surface of the transparent substrate is suitable. For example, a semiconductor laser, a YAG laser, an Ar ion laser, a carbon dioxide laser, a He-neon laser, a ruby laser , A dye laser, a KrF laser, a titanium sapphire laser and the like. The wavelength of the laser beam is preferably in the infrared region in terms of high light / heat conversion efficiency, and specifically, 600 to 1500 nm. If the wavelength is short, the light-to-heat conversion efficiency tends to decrease. Conversely, if the wavelength is long, it is difficult to narrow the beam, and it is difficult to draw a precise pattern.

The laser beam may be applied to the precursor polymer film imagewise through a mask, but it is preferable to directly irradiate the precursor polymer film by squeezing and scanning the beam because the number of steps is small. In particular, it is preferable that the data concerning the circuit is converted and controlled by a computer, and the image is directly irradiated like a picture by a raster method. For this reason, the laser beam is preferably of a continuous oscillation type (CW), and preferably of high output and high stability. Further, in order to reduce the cost, the laser itself is preferably inexpensive, and a semiconductor laser and a YAG laser are most preferable as the laser.

By exposing the laser, the precursor polymer film irradiated with the laser undergoes an elimination reaction to form a conjugated structure, thereby improving the conductivity and obtaining a conductive polymer. Furthermore, since the leaving group such as an onium salt structure is usually eliminated from the conductive polymer portion, the solubility in a solvent is reduced. By treating with a solvent capable of dissolving the precursor polymer, a desired conductive pattern can be formed. By forming the pattern into a circuit, a transparent conductive circuit can be obtained. Since the precursor polymer undergoes an elimination reaction due to heat as described above, it is preferable to remove the precursor polymer remaining in portions other than the conductive portion.
As the solvent used for removal, the same solvents as those exemplified for the coating can be used. By using the same solvent, the removed precursor polymer can be regenerated and recycled. As a removing method, the same method as a method usually performed in a developing operation of a photosensitive resin, such as a spraying method and a dipping method, can be adopted. Solvent treatment time is 1 to 90
The second and the temperature are preferably in the range of 15 to 35 ° C.

After the formation of the conductive polymer, the post-bake treatment is preferable because the post-bake treatment may further improve the conductivity. Post bake treatment is performed at a temperature of 100.
To 300 ° C., and the treatment time is usually 10 seconds to 6 seconds.
0 minutes. Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples unless departing from the gist thereof.

[0025]

EXAMPLE A methanol solution containing a precursor polymer of the formula (s-1) at a concentration of 1 wt% is applied to a plastic substrate having a surface treated with SiO ₂ and having a thickness of 0.4 mm with a wire bar. This is convection at 50 ° C, 30
Dry for seconds. The dry film thickness of the precursor polymer is about 0.2 microns. This sample was attached to a roller having a diameter of 10 cm, and was rotated at a rotation speed of 5 rpm while a wavelength of 83
Irradiation is performed with a semiconductor laser of 0 nm and output of 100 mw.
When the irradiated sample is immersed in water at 30 ° C. for 1 minute, and the laser non-irradiated portion is removed, a conductive polymer pattern is formed.

[0026]

According to the present invention, a circuit of a conductive polymer can be directly produced by laser light. transparency,
Since it is excellent in various properties such as conductivity and adhesion, it can greatly contribute to circuit formation such as a display. The manufacturing process can be significantly simplified, and is particularly useful for reducing the cost of a paper display or the like that is desired in the future.

Claims (6)

[Claims] 1. A method for producing a conductive polymer in which a conjugated double bond is generated by an elimination reaction of a precursor polymer having an elimination group, wherein the elimination reaction is started by a laser. A method for producing a polymer. 2. The method for producing a conductive polymer according to claim 1, wherein the group having an onium salt structure is eliminated to form a conjugated double bond. 3. The method for producing a conductive polymer according to claim 1, wherein the conjugated double bond has a basic skeleton of polyphenylenevinylene. 4. The method for producing a conductive polymer according to claim 1, wherein the laser has a wavelength in a range of 600 nm to 1500 nm. 5. A method for dissolving a precursor polymer in a solvent, applying the solution on a substrate, removing the solvent, and irradiating the obtained film containing the precursor polymer with a laser to cause a desorption reaction. A method for producing a conductive polymer according to claim 1. 6. A method for forming a conductive circuit, comprising using the conductive polymer obtained by the method according to claim 1.