JP3403429B2 - Method for producing conductive polymer molded article - Google Patents

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 molding. In particular, the present invention provides a transparent or non-black conductive polymer molded body that has conductivity for a long time and is not affected by environmental changes such as temperature and humidity, and as an antistatic material or an electromagnetic wave shielding material, It is useful for electronic / electrical products and construction fields.

[0002]

2. Description of the Related Art In recent years, with the rapid development of electric and electronic equipment, static sensitive parts have come to be used in various fields, and static control technology has become more important. Almost all general-purpose polymers and engineering plastics used for electric / electronic devices and indoor desks and floors in which they are placed are inherently insulating materials, so these polymer materials occur. The problem that static electricity impairs the normal operation of electronic components has been highlighted. In particular, an antistatic (that is, electrically conductive) material that is not affected by the environment is desired because the potential of the polymer material in the dry state is large. Further, a display device such as a cathode ray tube requires a transparent antistatic material.

Conventionally, in order to make a resin conductive, a method of adding carbon black or carbon fibers to the resin (for example, Japanese Patent Publication No. 3-50792), metal powders such as iron, copper, nickel and stainless steel, A method of adding fibers to a resin, and a method of kneading various cationic, anionic and nonionic surfactants into the resin (for example, JP-A-58-12).
5741, JP-A-64-24845, JP-A-1-135857) and the like are known.

However, it is difficult to obtain a transparent resin and the hue is limited by the method of adding carbon or metal to the resin. It also causes the mechanical properties of the resin to deteriorate. On the other hand, in the method using a surfactant, the antistatic effect is easily affected by the external environment such as humidity and temperature, and its durability is poor.

On the other hand, as a method for producing a conductive organic polymer, an electrolytic oxidative polymerization method and a chemical oxidative polymerization method are known.
The electrolytic oxidative polymerization method is a method in which an indicator electrolyte and a monomer to be polymerized are dissolved in a suitable solvent, and a constant voltage is applied between electrodes inserted in this solution to form a conductive organic polymer on the anode. . According to this method, it is possible to obtain a high conductivity of 10 S / cm or more, but mass production and large-scale production are difficult, and the production cost is high. Furthermore, the scope of this method is narrow, since the substrate must already be electrically conductive.

The chemical oxidation method is a method of oxidizing and polymerizing a monomer by using an oxidizing agent. One method is to dissolve the monomer in a suitable solvent and polymerize it with a suitable oxidizing agent. Compared to electrolytic oxidation polymerization method, this method
Although a polymer can be obtained at a low cost and has high mass productivity, it generally has low conductivity, the polymer can be obtained as a powder, and the polymer is generally insoluble and infusible. .

In order to improve such a defect of the conductive polymer, a method of impregnating a polymer molded body with a monomer and then polymerizing the monomer with an oxidizing agent to prepare a conductive composite molded body is disclosed in Japanese Patent Laid-Open Publication No. 62-167329 and JP-A-62-16733.
No. 0 publication. However, there is no known method for obtaining a polymer molding having good transparency (or not black) and high conductivity.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the conventional method of imparting conductivity to an insulating polymer material, and improves the transparency or color and the mechanical properties of the polymer material. Provided is a method for producing a conductive polymer molded body by imparting stable conductivity without impairing it.

[0009]

The inventors of the present invention obtained an aromatic compound, in particular, a heterocyclic compound (monomer) containing a heteroatom such as nitrogen, oxygen and sulfur, and dissolving this in a solvent. By contacting the solution with the insulating polymer molded body that is the base material, the base material is impregnated with the monomer, and then a process of making the surface of the base material conductive by contacting it with a solution containing an oxidant. As a result of a detailed study, by using a solvent (non-solvent) that does not dissolve the polymer constituting the substrate in the solvent, stable conductivity is imparted without impairing the transparency, color, or mechanical properties of the substrate. The present invention has been achieved and has reached the present invention.

That is, according to the present invention, an insulating polymer molded body (base material) is brought into contact with a solution (diffusion solution) containing one or more compounds (monomers) selected from heterocyclic compounds to form a base material. The monomer is impregnated into the surface of the base material and the vicinity of the surface (diffusion step), and this is immersed in a solution containing an oxidant to polymerize the monomer on the surface of the base material and inside the surface (oxidation polymerization step). In the method for producing a polymer molded body, the solvent used for the diffusion solution is 1) a solvent that does not dissolve the polymer constituting the substrate (non-solvent)
And the solubility parameter of the non-solvent is the solubility of the base polymer
Degree parameter -3 (MPa) ^1/2 to +3 (MPa) ^1/2
Of at least one non-solvent in a volume ratio of 5 to 5
A mixture of two or more non-solvents containing 50%, or
Is 2) solvent for dissolving the polymer constituting the base material (the good solvent)
It is a mixed solvent with non-solvent, and the content of good solvent is 5% by volume.
And a mixed solvent of less than 1% .

The non-solvent used in the solution containing the monomer in the diffusion step of the present invention is a solvent which does not dissolve the polymer constituting the substrate or does not dissolve the polymer, but the good solvent means a group. It is a solvent that dissolves the polymer that constitutes the material to give a uniform solution. The specific types of these differ depending on the polymer (reference, "Polymer Handbook", 3rd edition, JOHN WILEY & SONS,
1989). For example, when the base material is polyvinyl chloride, the good solvent is cyclohexanone, nitrobenzene, butyl acetate, dichloroethane, tetrahydrofuran, methyl isobutyl ketone, methyl ethyl ketone, dimethylformamide, etc., and the non-solvent is methanol, ethanol, n-butanol. , Ethylene glycol, n-hexane, benzene, acetone and the like.

When the solvent used in the monomer solution is a mixture of a non-solvent and a good solvent, the content of the good solvent is preferably less than 5% by volume. More preferably, it is less than 2% by volume. However, the non-solvent and good solvent mentioned here are
Each does not have to be a single solvent, and may be a mixture of a plurality of solvents. If the composition of the solvent does not satisfy these conditions, there is a high risk that the conductivity of the finally obtained polymer molded article will be low, the surface will be uneven, and the transparency will deteriorate due to coloring etc. .

Further, in the present invention, the solvent used for the monomer solution preferably contains a non-solvent having an affinity for the base polymer in an amount of 5 to 50% by volume. The non-solvent having an affinity for the base polymer here means that the solubility parameter is -3 (M of the solubility parameter of the base polymer).
It is a non-solvent that falls within the range of Pa) ^1/2 to +3 (MPa) ^1/2 .

In the diffusion step, the monomer concentration of the solution containing the monomer is preferably 0.5 to 20% by weight, more preferably 1 to 10% by weight. The time for bringing the polymer molding of the base material into contact with this monomer solution is preferably 20 seconds to 30 minutes, more preferably 1 minute to 10 minutes. This contact time is 20
If it is shorter than a second, the impregnation of the base material with the monomer becomes insufficient, and finally a polymer molded body having high conductivity cannot be obtained.
If the contact time is longer than 30 minutes, not only the base material may be deformed, the transparency of the finally obtained polymer molded article may be deteriorated, but also the manufacturing cost is increased.

The monomer selected from the heterocyclic compound and the aniline compound used in the present invention is a monomer which becomes a polymer composed of a conjugated chain when oxidatively polymerized. Examples of such a monomer include a pyrrole derivative, a furan derivative and a thiophene derivative in a 5-membered heterocyclic compound, and an aniline in a 6-membered heterocyclic compound.
Examples thereof include benzidine.

Pyrrole derivatives include unsubstituted pyrrole, N-substituted pyrrole such as N-alkylpyrrole, and 3
Position or 3-position and 4-position an alkyl group _C 1 -C _6, 3-alkyl-pyrrole having an alkoxy group or a halogen atom, 3,4-dialkyl pyrrole, 3-alkoxy-pyrrole, 3,4-dialkoxy-pyrrole, 3 -Chloropyrrole and 3,4-dichloropyrrole.

Examples of the furan derivative include unsubstituted furan and a C ₁ -C ₆ alkyl group at the 3-position or 3- and 4-positions,
There are 3-alkylfuran having an alkoxy group or a halogen atom, 3,4-dialkylfuran, 3-alkoxyfuran, 3,4-dialkoxyfuran, 3-chlorofuran and 3,4-dichlorofuran.

As the thiophene derivative, an unsubstituted thiophene and a 3- or 3-positioned C ₁ -C ₆ alkyl group, alkoxy group or halogen atom at the 3-positions are used.
Alkylthiophene, 3,4-dialkylthiophene,
There are 3-alkoxythiophene, 3,4-dialkoxythiophene, 3-chlorothiophene, 3,4-dichlorothiophene and the like.

The oxidizing agents used in the present invention include metal-based and non-metal-based oxidizing agents, but oxidation having an oxidation potential similar to that of the electrolytic oxidative polymerization method for producing a highly conductive polymer in a reaction medium. Agents are preferred. Examples of the metal-based oxidizing agent for pyrroles, furans, and thiophenes include iron (III) salts, molybdenum (V) salts, ruthenium (III) salts, and the like. On the other hand, examples of the non-metal oxidant include persulfates such as ammonium persulfate, peroxides such as hydrogen peroxide and benzoyl peroxide, peroxodisulfuric acid such as peroxodisulfuric acid and potassium peroxodisulphate, hypochlorous acid, and There are chloric acids such as potassium chlorite.

Depending on the application such as an IC tray or an IC carrier tape, it is necessary to wash the polymer molding coated with a conductive film with pure water to remove residual metals or to use a non-metallic oxidizer. There is.

When a non-metallic oxidant is used as the oxidant, a better high-conductivity polymer molding can be obtained by coexisting a doping agent in the reaction medium. Such doping agents include Lewis acids, protic acids and salts thereof. Protonic acids include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as toluenesulfonic acid and dodecylbenzenesulfonic acid. Examples of Lewis acids include arsenic pentafluoride, antimony pentafluoride, boron trifluoride, boron trichloride, ferric chloride, stannic chloride, titanium tetrachloride, zinc chloride, cupric chloride and the like. .

The polymer molding in the present invention may be either thermosetting or thermoplastic and is not particularly limited. Examples of thermoplastic resins include polyolefins (polyethylene, polypropylene, ethylene-vinyl acetate copolymer, etc.), polyvinyl chloride, polystyrene, ABS.
Resin, polyamide (nylon 6, nylon 66, nylon 12, etc.), polyimide, polyethylene terephthalate (PET), polybutylene terephthalate (PB)
T), polyesters including polyesters showing optical anisotropy, polycarbonate, polyether ether ketone, polyether ketone, polyoxymethylene, polyethylene oxide, polypropylene oxide, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether sulfone, etc. There is. Examples of thermosetting resins include phenolic resins, unsaturated polyesters, epoxy resins and the like.

These polymer moldings include stabilizers, plasticizers, flame retardants, additives such as lubricants, reinforcing materials such as glass fibers and whiskers, inorganic fillers such as calcium carbonate, clay, silica, mica and talc. May be added.

The solvent used for the solution containing the oxidizing agent in the oxidative polymerization step of the present invention must be such that the oxidizing agent is not isolated and precipitated and is not subjected to the oxidation reaction by the oxidizing agent. Examples of such solvents include water, methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, octanol and other aliphatic alcohols, hexafluoroisopropanol and other halogenated alcohols, phenol, chlorophenol, cresol, fluoro. Phenols such as phenol and polar solvents such as dimethylacetamide and acetonitrile are preferable. Furthermore, hydrocarbons such as benzene, toluene, xylene, hexane, and cyclohexane, halogenated compounds such as chloroform, and nonpolar solvents such as various ethers can be mentioned as candidates. In this case, since the oxidation potential differs depending on the type of solvent, by appropriately mixing and using a solvent that gives a high oxidation potential and a solvent that gives a low oxidation potential, an oxidation potential suitable for obtaining a highly conductive polymer can be obtained. It can be adjusted to.

The solvent used in the oxidative polymerization step must be one that does not dissolve or greatly swell the polymer molding of the base material, and is a non-solvent for the polymer constituting the base material. Desirably, it may be a mixture of a plurality of non-solvents. In addition, the good solvent for the polymer that constitutes the substrate is 5
A mixed solvent containing less than volume% can also be used.

According to the studies by the present inventors, the conductivity of the conductive polymer formed on the surface of the polymer molded body largely depends on the oxidation potential during the oxidative polymerization. That is, if the oxidation potential is too large or too small, the conductivity becomes low. The oxidation potential during the polymerization reaction can be controlled by the type of solvent, the oxidant / reductant ratio of the oxidant, and the temperature. For example, when 1M ferric chloride solution was used as an oxidant for polymerizing pyrrole, the oxidation potential was 136 when acetonitrile was used as a solvent.
It becomes 0 mV, 560 mV for methanol and 380 mV for dimethylformamide. Of these,
The highest conductivity is obtained when methanol is used. In addition, a reductant (FeCl ₃ ) of an oxidant (eg, FeCl ₃ )
_The oxidation potential can also be adjusted by adding ₂ ). In this case, the reductant to be added is 50 mol% or less, preferably 0.01 to 20 mol% with respect to the oxidant, and at this time, an oxidation potential for increasing the conductivity of the produced polymer is obtained.

After the oxidative polymerization step, it is desirable to thoroughly wash the polymer molding to remove the remaining oxidizing agent and its reduced product. As the solvent, those similar to those used in the oxidative polymerization step can be used. Furthermore, after washing, it is desirable that the polymer molded article be thoroughly dried to remove the residual solvent. If an oxidant or its reduced product or solvent remains in the resulting conductive polymer molded product, it may cause deterioration of the conductive coating film on the surface due to heat during secondary molding of this, or gas during use. May cause the occurrence of.

In the present invention, in order to impart conductivity without impairing the hue and transparency of the substrate, the thickness of the conductive film formed on the surface is preferably 0.02 μm to 20 μm, more preferably It is 0.05 μm to 5 μm.
If the thickness of the coating is less than 0.02 μm, sufficient conductivity cannot be obtained, and if it is greater than 20 μm, the transparency becomes poor, and the coating may be cut or peeled during molding, and the conductivity is likely to be impaired. Problems may occur.

Further, in the present invention, the conductive polymer produced by the above-mentioned oxidative polymerization is chemically or electrochemically reduced, and then oxidized by chemical oxidation or electrolytic oxidation and doping is performed to obtain an antistatic effect. It can be further enhanced. Examples of the reducing agent used for the chemical reduction include hydrazine, hydrazine hydrate, hydrazine such as phenylhydrazine, lithium aluminum hydride,
Examples thereof include metal hydrides such as sodium borohydride. The chemical reducing agent is usually used in a molar amount of 1 to 10 times per nitrogen atom of the polymer, but is not necessarily limited thereto. In the electrolytic reduction, the surface of the molded body is used as a cathode, and a current is applied at an applied voltage of 0.01 to several tens of V to dedope. After the reduction, the neutral conductive polymer film is chemically re-oxidized with an oxidant and doped. As the dopant used for such re-doping, any compound having an oxidizing power sufficient for re-oxidizing a reduced neutral polymer and having an electron accepting property effective as a dopant can be used. Such oxidizing agents include halogens such as iodine, bromine and chlorine, arsenic pentafluoride, antimony pentafluoride, boron trifluoride, boron trichloride, ferric chloride, stannic chloride, titanium tetrachloride, Lewis acids such as zinc chloride and cupric chloride, hydrochloric acid, sulfuric acid and salts thereof (for example, potassium hydrogen sulfate, sodium sulfate, sodium perchlorate, potassium perchlorate, iron perchlorate, etc.), or borofluoric acid. And salts thereof (for example, sodium borofluoride, potassium borofluoride, ammonium borofluoride, tetraalkylammonium borofluoride, etc.) and the like.

It is also possible to carry out oxidation and doping again electrochemically. In this case, the oxidizing agent may be used as the indicator electrolyte, and the conductive polymer film may be used as the anode to pass an electric current.

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0032]

EXAMPLES In the following examples, the surface resistivity of the film was measured using a surface resistance measuring device Loresta AP (manufactured by Mitsubishi Yuka).

Example 1 360 ml of n-hexane, 40 ml of acetone, 10
1 ml of the solution (diffusion solution) obtained by mixing ml of pyrrole
A hard vinyl chloride film having a size of 30 mm × 170 mm and a thickness of 0.3 mm was immersed at room temperature for 3 minutes to impregnate pyrrole into the film. This film was immersed in a 2.5 M ferric chloride methanol solution (oxidizing solution) at room temperature for 5 minutes to polymerize the pyrrole impregnated near the surface of the film. Then, the remaining iron chloride was removed by immersing the film in methanol for 10 minutes, and the film was dried under reduced pressure for about 10 hours.

Here, n-hexane, methanol and acetone are non-solvents of polyvinyl chloride.
Acetone is a solvent that does not dissolve polyvinyl chloride but swells. Polyvinyl chloride film is 100 parts of vinyl chloride resin (polymerization degree about 800), diethyl tin malate 3
Parts, 10 parts of MBS resin, and 3 parts of epoxidized soybean oil.

The film was not deformed by the above treatment, and the cross section of the obtained film was observed by a transmission electron microscope to find that the polypyrrole phase was distributed at a depth of about 0.1 μm from the surface. Was confirmed. The surface resistivity of the film was 7 to 30 KΩ / □, and the film had sufficiently large conductivity as an antistatic material. Further, although the film was slightly brown, the light transmittance was around 30% in the visible region and the transparency was good. further,
No peeling of the conductive layer on the film surface was observed at all in the cross-cut test and the peeling test using cellophane tape defined in JIS K5400.

Example 2 The diffusion solution used in Example 1 was 140 ml of acetone, 50 ml of acetonitrile, 8 ml of methanol and 6 parts of pyrrole.
A polyvinyl chloride film was treated in the same manner as in Example 1 except that a mixed solution of ml was used. The surface resistivity of the obtained film was about 120 KΩ / □, which was higher than that of Example 1, but sufficient for preventing static electricity. Further, the transparency of the film is almost the same as in Example 1, and J
No peeling of the conductive layer on the film surface was observed in the cross-cut test and the peeling test using cellophane tape defined in IS K5400.

Example 3 A polyvinyl chloride film was treated in the same manner as in Example 1 except that the diffusion solution in Example 1 was a mixed solution of 190 ml of benzene and 10 ml of pyrrole. The surface resistivity of the obtained film is 15 to 45 KΩ / □, and
Although the value was slightly higher, it was a sufficient value for preventing static electricity. The transparency of the film is about 2 in the visible range.
It was around 0%, and no peeling of the conductive layer on the film surface was observed at all in the cross-cut test and the peeling test with cellophane tape defined in JIS K5400.

Comparative Example 1 In Example 1, the diffusion solution was 200 ml of methyl ethyl ketone, which is a good solvent for polyvinyl chloride, and 7 ml of pyrrole.
A polyvinyl chloride film was treated in the same manner as in Example 1 except that the mixed solution of 1. The surface resistivity of the obtained film was as high as about 1 MΩ / □, the film was greatly deformed by the treatment, and the transparency was significantly poorer than that of Example 1.

COMPARATIVE EXAMPLE 2 In Example 1, the diffusion solution was changed to 360 m of n-hexane.
l, cyclohexanone (good solvent for polyvinyl chloride) 40
ml, and a polyvinyl chloride film was treated in the same manner as in Example 1 except that a mixed solution of 10 ml of pyrrole was used. The surface resistivity of the obtained film was a high value of 1 MΩ / □ or more.

Comparative Example 3 The diffusion solution used in Example 1 was 188 m of acetonitrile.
1, nitrobenzene (good solvent of polyvinyl chloride) 12m
A polyvinyl chloride film was treated in the same manner as in Example 1 except that a mixed solution of 1 and 5 ml of pyrrole was used. The surface resistivity of the obtained film was a low value of about 17 to 50 KΩ / □, but the surface was uneven and the transparency of the film was poor at about 5 to 10% in the visible region.

[0041]

EFFECTS OF THE INVENTION According to the present invention, it is possible to easily produce a polymer molded body having a conductive surface. At this time,
The transparency and hue of the base material are not significantly impaired,
The obtained conductivity lasts for a long time and is hardly affected by temperature and humidity. Therefore, the present invention can be applied to electronic / electrical parts,
When used in materials such as cases and IC trays or in the field of building materials, it is extremely useful for preventing damage to semiconductors due to static electricity and explosion accidents due to discharge.

Continuation of front page (51) Int.Cl. ⁷ identification code FI C09D 5/24 C09D 5/24 (56) References JP-A-62-167330 (JP, A) JP-A-3-8872 (JP, A) JP-A 1-229032 (JP, A) JP-A 1-170615 (JP, A) JP-A 60-148012 (JP, A) JP-B 3-63971 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01B 13/00 H01B 1/00-1/24 H01B 5/00-5/16 C08J 7/00-7/18

Claims (5)

(57) [Claims] 1. An insulating polymer molding (base material) is brought into contact with a solution (diffusion solution) containing at least one compound (monomer) selected from heterocyclic compounds, and the monomer is added to the surface and the surface of the base material. In a method for producing a conductive polymer molded article, which is characterized by impregnating the interior of the vicinity, immersing it in a solution containing an oxidant, and polymerizing a monomer on the surface of the base material and in the vicinity of the surface, a diffusion solution. The solvent used for 1) is a solvent that does not dissolve the polymer that constitutes the base material (non-solvent)
And the solubility parameter of the non-solvent is the solubility of the base polymer
Degree parameter -3 (MPa) ^1/2 to +3 (MPa) ^1/2
Of at least one non-solvent in a volume ratio of 5 to 5
A mixture of two or more non-solvents containing 50%, or
Is 2) solvent for dissolving the polymer constituting the base material (the good solvent)
It is a mixed solvent with non-solvent, and the content of good solvent is 5% by volume.
The method for producing a conductive polymer molded body is characterized in that it is any one of the following mixed solvents . 2. The diffusion solution has a monomer concentration of 0.5.
It is 20 weight% or less, The manufacturing method of the electroconductive polymer molded body of Claim 1 characterized by the above-mentioned. 3. The method for producing a conductive polymer molding according to claim 1, wherein the monomer is selected from pyrrole series, furan series and thiophene series. 4. The electroconductive polymer molding according to claim 1, wherein the oxidizing agent is an iron (III) salt, a molybdenum (V) salt, a ruthenium (III) salt or a persulfate salt. Manufacturing method. 5. When a non-metallic oxidant is used as the oxidant,
In this case, the solution containing an oxidizing agent contains any one of an inorganic protonic acid, an organic protonic acid, or a salt thereof as a doping agent. Method for manufacturing molded body.