JPH0419253B2 - - Google Patents

Description

[Detailed description of the invention]

Field of the Invention The present invention relates to a process for making electrically conductive polymer blends. In particular, the present invention relates to a method for producing an electrically conductive polymer mixture using a non-porous polymer as a matrix. BACKGROUND OF THE INVENTION Electrically conductive polymers have been the subject of much interest because of their potential use as replacements for metal conductors and semiconductors in a variety of applications such as batteries, photovoltaics, electrostatic dissipation, and electromagnetic shielding. ing. The advantages of conductive polymers over conventional metal conductors are that they are lighter in weight, cheaper, and can be produced in a variety of different ways through synthesis and processing methods. However, most of the electrically conductive polymer systems currently produced are still insufficiently stable and processable for use in such applications. Conductive polymer admixtures (i.e., conductive polymers that are intimately mixed with one or more conventional polymers) have already been developed by some researchers into conductive polymers. However, it has been created as a means to improve the environmental stability and/or mechanical properties. A further advantageous aspect of this type of polymeric blend is that the conductive polymeric component can be synthesized inside a suitably processed polymeric matrix, such as a thin film or fiber. This means that there is no need to process the ingredients. There are roughly the following three methods for obtaining a conductive polymer mixture. (1) The conductive polymer and the base polymer are dissolved together in a compatible solvent, and then the solvent is removed. (2) A catalyst, a monomer, and a doping agent are impregnated into a matrix polymer in this order so that the chemical reaction necessary to generate the conductive polymer occurs within the polymer matrix. (3) A polymer film serving as a matrix is coated on the electrode surface, and then this polymer-coated electrode is used as an anode to synthesize a conductive polymer from an appropriate monomer and electrolyte using an electrochemical anode. The first method listed above uses a doped phthalocyanine polymer as a conductive polymer, an aramid polymer as a matrix polymer, and a strong acid (sulfuric acid, trifluoromethanesulfonic acid) as a solvent. It is actually being done. Journal of, Chemical, Society, Chemical Communication,
1983, pp. 1084-1085, "Spun fibers and fiber blends of electrically conductive polymers", T. Inabe, JW
Lideng and TJ Marks and Macromolecules 1984, 17 , 260-262, correspondence to the editor, Processable materials consisting of oriented electrically conductive hybrid molecules/macromolecules, T. Inabe, JF Lomatskus, TJ Marks, JW Riding, C.
Reference R. Cannewulf and KJ Wein. in general,
This method cannot be used with other known conductive polymers. This is because such conductive polymers are insoluble in all common solvents. The second method listed above is based on polyacetylene/
Used to make polymer blends. In that method, the host polymer is first impregnated with a Ziegler-Natsuta catalyst solution, then with acetylene gas (monomer), and finally with an iodine dopant. Polymer, 1982, Volume 23, June issue, 795
-797 page "Electrically conductive polymer compositions: Polymerization of acetylene in polyethylene", MB Galvin and GE Nek; Macromolecules 1983,
16, 870-875 Structure-property relationships of polyacetylene/polybutadiene blends, MF Lubner, SK
Tripathy, J. Shiyojia Jr. and P. Kholewa,
See also US Pat. No. 4,394,304. This method is difficult to implement because it requires a strict inert atmosphere and vacuum piping techniques. Additionally, the resulting polyacetylene/polymer blends are generally not as environmentally stable as the polyacetylene itself. The third method listed above is used to create a thin polypyrrole/polymer film blend by electrochemical oxidation of the pyrrole monomer on the polymer-coated electrode surface. Ta. The thin film mixture thus obtained has good stability (like the polypyrrole itself) and good mechanical properties (due to the parent polymeric component).
Journal of Chemical Society, 1984, pp. 1015-1016, "Electrically conductive compositions consisting of poly(vinyl chloride) and polypyrrole" MA De Paoli, RJ Waltman, AF
Diaz, and J. Burgon and the Journal of,Chemical,Society,Chemical Communication,.
See O. Niwa and T. Tamamura, "Polymerization of pyrrole and polymer-coated electrodes," 1984, pp. 817-818.
The main disadvantages of this method are that it is limited to very thin films and that it is difficult to carry out on a large scale because it requires multiple batch operations. Similar to the recently discovered electrochemically produced thin films of conductive polypyrrole, chemically derived polymeric materials derived from pyrrole are well known. Such materials are commonly referred to as "pyrrole black" and are produced by chemical oxidation of pyrrole. GP Gardeini, “Oxidation of monocyclic pyrroles,” Advances of Heterocyclic Chemistry 15, 67-98 (1973)
and references cited therein. Similarly, the terms "aniline black" and "emeraldine" refer to the long-known, well-known polymeric substances obtained by the chemical oxidation of aniline; This is contrasted with a thin film of polyaniline. American Chemical Society International Convention, Polymer Preprint, August 1984, pp. 248-249, “Polyacetylene and “Polyaniline”
'Aqueous Chemistry and Electrochemistry: Applications to Rechargeable Batteries', AJ McDeamid, JC Shiyan,
M. Halpern, WS Huang, JR Karuchik,
RJ Mammon, SL Mu, NLD Somasiri and
See W. Wu. Such chemically produced materials derived from pyrrole and aniline are generally insoluble powders that are brittle and difficult to process. However, methods have recently been described to generate pyrrole black within the interstitial spaces of porous solids, and sequential treatment of paper with a chemical oxidant and pyrrole rendered the paper electrically conductive. Journal of Electronic Materials, Volume 13, No. 1,
1984, pp. 211-230, "Some Properties of Polypyrrole-Paper Compositions", RB Björklund and I. Lundström, and December 22, 1983
See German application No. P33 21 281.3 published in Japan. This method shows that pyrrole black can be used as a conductive coating on porous materials such as textiles, foam, pumice, porcelain and paper. However, there is no indication that they can be used in polymer mixtures in which the host polymer is non-porous. All of the above-mentioned prior art related to conductive polymers and polymer blends are inexpensive, have high conductivity, have good environmental stability, can be processed in any way, and can be easily machined. This does not mean providing a single electrically conductive polymer system that has both good physical properties. Therefore, the potential for conductive polymers to replace metal conductors has not yet been realized. OBJECTS OF THE INVENTION One of the objects of the present invention is to have the following properties: low cost, high electrical conductivity, good environmental stability, can be processed in any way, and has good mechanical properties. The object of the present invention is to provide an electrically conductive polymer substance that has the following properties. Another object of the present invention is to provide an electrically conductive polymer blend. A further object of the present invention is to provide a method for increasing the electrical conductivity of normally insulating polymeric materials by simple chemical means carried out as a kind of post-treatment method. A further object of the present invention is to improve the electrical conductivity of polymeric materials without relying on conductive surface coatings or conductive filler particles, and also to substantially improve the mechanical properties of the parent polymer. The purpose is to provide a method for increasing without changing. Purposes other than these will become clearer from the description below. DESCRIPTION OF THE INVENTION The present invention comprises impregnating a non-porous swellable or soluble host polymer with (a) and (b) as follows, in any order: This invention relates to a chemical oxidation method for producing conductive polymer blends. (a) one or more cyclic compounds selected from the group consisting of pyrrole, aniline and substituted analogs thereof, and (b) trivalent iron compounds, tetravalent cerium compounds, 6
At least one chemical selected from the group consisting of valent molybdenum, tungsten or chromium compounds, divalent copper compounds, monovalent silver compounds, nitrites, quinones, peroxides and peracids. an oxidizing agent that can be dissolved in a solvent that can swell or solubilize the parent polymer. As used herein, the term "non-porous swellable or soluble parent polymer" includes elastomers and also includes thermoplastic polymers. Therefore, the elastomers used herein include, but are not limited to, acrylonitrile-butadiene-styrene copolymers,
Butadiene-styrene copolymer, chloroprene-
Contains acrylonitrile copolymer, chlorosulfonated polyethylene, ethyl acrylate-chloroethylene vinyl ether copolymer, isobutylene-isoprene copolymer, isobutylene-styrene copolymer, polychloroprene copolymer, polyisobutylene, polysulfide, silicones, etc. . The thermoplastic polymers used here as the base polymer include, but are not limited to, copolymers of polyvinyl chloride and higher vinyl chloride, polyvinyl acetate, vinylidene chloride copolymers, polyvinyl butyral,
Polyvinyl alcohol, polyvinylacetaldehyde acetal, polyvinyl formal, polycarbonate, polypropylene, polyurethane, tetrafluoroethylene, chlorotriflyoethylene, polystyrene, styrene copolymers such as styrene-acrylonitrile and styrene-butadiene, ethyl cellulose, Including cellulose acetate, cellulose acetate butyrate, cellulose propionate, cellulose acetate propionate, cellulose nitrate, acrylonitrile, polyamide, polymethacrylate, polyacrylate, ethylene terephthalate polymer, etc. The elastomers and thermoplastic polymers described above must be inert to the cyclic compounds and chemical oxidizing agents used in conjunction with the parent polymer to form the electrically conductive polymer blend. Furthermore, the elastomers and thermoplastic polymers are such that the cyclic monomer is swellable in at least one of the solvents of the chemical oxidizing agent because reactions can occur within the polymer. Or it must be soluble. As mentioned above, the impregnation of the host polymer with the cyclic monomer and the chemical oxidizing agent can occur in either order. That is, if the parent polymer is swellable or soluble by a cyclic monomer, the cyclic monomer is used first to impregnate the parent polymer and then dissolved in a solvent. Impregnation using a chemical oxidizing agent. Alternatively, the host polymer can be impregnated first with a chemical oxidizing agent dissolved in a solvent and then with a cyclic monomer. In a preferred embodiment of the invention, the host polymer is first impregnated with a chemical oxidizing agent dissolved in a solvent, followed by impregnation with a cyclic monomer. The host polymer may be in the form of a film, plate, powder, fiber, or other preformed shapes. Therefore, for example, a rubber plate of the base polymer may be made. If this is done later using the method of the present invention, it can be made electrically conductive. The cyclic monomers used herein to impart electrical conductivity to the host polymer are selected from the group consisting of pyrrole, aniline and substituted analogs of these monomers. Such analogs include, but are not limited to, N-methylpyrrole, 3-methylpyrrole, 3,5-dimethylpyrrole, 2,2'-bipyrrole, N-methylaniline, 2-methylaniline. , 3-methylaniline and N-phenyl-1,4-diaminobenzene. When carrying out the present invention, a cyclic monomer and a solvent that swells or solubilizes the base polymer may be used in combination. When this combination is used, the monomers are usually present in amounts up to 25% by weight. Monomers are usually added in liquid form, but may also be added as vapor. The chemical oxidizing agents used here are compounds containing metal ions whose valence can vary.
Such substances include, for example, FeCl ₃ Fe ₂ (SO ₄ ) ₃ ,
K ₃ [Fe(CN) ₆ ], H ₃ PO ₄・12M ₀ O ₃ , H ₃ PO ₄・
_12WO3 , _CrC3 ( _NH4 ) _2Ce ( _NO3 ) ₆ , Ce( _SO4 ) ₂ ,
There are CuCl ₂ and AgNO ₃ . A particularly preferred chemical oxidizing agent from the above set is iron trichloride. In the present invention, nitrites, quinones, peroxides,
Metal-free compounds such as peracids and peracids can also be used as chemical oxidizing agents. Such metal-free compounds include, but are not limited to, HNO ₂ , 1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4
-benzoquinone, 2,3-dichloro-5,6-dicyano-1,4-benzoxon, hydrogen peroxide, peroxyacetic acid, peroxydorinzoic acid, 3-chloro-peroxydatenzoic acid and ammonium persulfate. A particularly preferred chemical oxidizing agent from the above set is ammonium persulfate. In the practice of this invention, auxiliary acids including, but not limited to, mineral acids, organic carboxylic acids, and sulfonic acids may be used in conjunction with the inorganic or organic oxidizing agents described above. Therefore, sulfuric acid, hydrochloric acid,
Acetic acid, trifluoroacetic acid, methanesulfonic acid or trifluoromethanesulfonic acid can be used. Such acids may be dissolved together with the oxidizing agent in a suitable solvent, or may themselves be used as a solvent for the oxidizing agent. The primary role of the auxiliary acid is to act as a catalyst for the oxidative polymerization process. Although the addition of such acids is preferred, they need not always be used in conjunction with the preferred oxidizing agent. 0.01 per mole of oxidizing agent if an auxiliary acid is added to the system.
Added in amounts ranging from ~100 moles of acid. Polymerization of the cyclic monomer in the parent polymer is usually carried out at room temperature under conditions that are not particularly different from usual. Appropriate selection of oxidizing agents, monomers, solvents, and processing conditions such as operating time and temperature can control conductivity, physical appearance, and penetration of the conductive polymer into the host polymer surface. The final properties of the polymer blend can be controlled, such as the depth and weight gain of the host polymer due to the conductive polymer component. Typical ranges of properties that can actually be obtained are as follows. Electrical conductivity (S/cm): 10 ^-10 ~ 1 Appearance: black, gray, green, translucent or opaque. Penetration depth of conductive polymer (microns): 1~
1000 Weight increase due to conductive polymer: 0.1% to 20% The molar ratio of cyclic monomer to oxidant in the host polymer is
It is within the range of 0.01 to 100. The stoichiometry of the reaction between a one-electron oxidant and pyrrole to produce oxidized polypyrrole requires a molar ratio of oxidant to pyrrole of 2:1 to 3:1. Conductive polymers formed by the method of the invention can be used as metallic conductors or semiconductors in applications such as static dissipation and electromagnetic shielding. The following examples will serve to illustrate the invention. However, it is not limited to this.
All parts and percentages are by weight unless otherwise noted. Example 1 Polyvinyl acetate (0.2 g) is dissolved in ethyl acetate (2 ml) containing 5% by volume of pyrrole. The resulting solution is spread onto a glass slide into a thin film (20 microns thick) and the solvent is allowed to evaporate. The coated glass slide is then immersed in a solution of iron trichloride (0.1M) in hydrochloric acid (0.01M). Within one hour, the film becomes gray and translucent in the areas exposed to the oxidizing agent, while remaining transparent in the unexposed areas. Wash the glass slides with water and dry for 30 minutes at room temperature. The gray portion of the film has a surface resistance of approximately 10 ^-4 ohms between two contact points 0.5 cm apart, while the unexposed portion has a surface resistance of greater than 10 ¹⁰ ohms. Example 2 Coarse powder of polyvinyl chloride (0.25 g) was mixed with acetonitrile (2 by volume) containing 5% by volume of pyrrole.
ml) and stirred at room temperature for 1 hour. The resulting powder is collected by filtration, suspended in the iron trichloride solution of Example 1, and then stirred for 30 minutes at room temperature. The resulting black powder is collected by filtration, washed with water and dried under vacuum. This powder exhibits a specific conductivity of 4 x 10 ^-3 S/cm when compressed (4000 psi). Example 3 Polyvinyl chloride (0.25% by volume) in tetrahydrofuran (2 ml) containing 10% by volume of pyrrole
Spread the solution containing g) on a glass slide in the same manner as in Example 1. The resulting thin film is peeled off from the glass surface and then immersed in the iron trichloride solution of Example 1 for 1 hour. The resulting gray translucent film is washed with water and dried under vacuum. The specific conductivity of this film is 10 ^-4 S/cm. Example 4 A sample of nylon staple fiber (diameter
30 microns, 0.46 g) in acetonitrile containing 10% pyrrole by volume. After a period of time at room temperature, the fiber sample is removed, washed with distilled water, and immersed in the iron trichloride solution of Example 1 for 1 hour at room temperature. The resulting gray fiber is removed, washed with distilled water and dried under vacuum overnight. The treated fiber exhibits the following properties (properties before treatment are shown for comparison)

[Table] Example 5 A sample of polyurethane rubber with a smooth surface and dimensions of 33.2 x 2.5 x 0.5 cm is immersed in acetonitrile containing 5% by weight of iron trichloride hexahydrate. After one hour at room temperature, the sample is removed, blotted dry, and immersed in petroleum ether containing 10% by volume of pyrrole. After one hour at room temperature, the sample is removed and dried at room temperature for 72 hours. The treated sample exhibits the following properties (properties before treatment are shown for comparison)

[Table] The cross section of the sample to be treated above shows that the black color generated in the polymer penetrates to a depth of about 0.5 mm (500 microns) from the polymer surface, and the interior remains transparent. Show that. Example 6 Polypynylacetate (0.2 g) in ethanol (2 ml) containing iron trichloride trihydrate (0.1 M)
dissolve. This yellow solution is spread onto a glass slide to form a thin film (20 microns) and the solvent is evaporated under a stream of nitrogen. The coated slides are then immersed in petroleum ether containing 10% by volume of pyrrole. The film is removed from the solution after 10 minutes. The surface resistance of the treated (black) film was approximately 10 ⁵ ohms (two probes 1 cm apart);
Similar films that were not exposed to pyrrole or impregnated with iron trichloride before exposure to pyrrole were over 10 ¹⁰ ohms. Example 7 The polyvinyl acetate/iron trichloride film of Example 6 is held over the mouth of a small beaker containing pyrrole. When this pyrrole is warmed on a hot plate, it can be seen that within a few minutes, the part of the pyrrole exposed to the steam changes from transparent yellow to dark brown. The resistance measured at the exposed surface is approximately 10 ⁵ ohms (two tips, 0.5 cm apart). Example 8 Hydrochloric acid (0.01M) containing iron trichloride (0.1M)
Dissolve polyvinyl alcohol (0.2g) in 2ml of. The resulting solution is spread onto a glass slide to form a thin film (20 microns) and allowed to dry at room temperature for 1 hour. When this glass-backed film is then immersed in acetonitrile containing 10% by volume of pyrrole, the color of the film changes rapidly, turning from transparent yellow to dark brown. Remove from the glass surface and clean with acetonitrile. The specific conductivity of the resulting film was measured on both the exposed and unexposed sides of the film.
It was 0.03S/cm. Example 9 Polyvinyl chloride (0.2 g) in tetrahydrofuran (2 ml) containing 10% aniline by volume
dissolve in The resulting solution is spread out into a thin layer as in Example 1 and dried at room temperature for 1 hour.
This glass-backed polymer film was then immersed in a 10% ammonium persulfate solution dissolved in hydrochloric acid (0.1M). After leaving it at room temperature for 1 hour, take out the film, wash it with distilled water, and leave it at room temperature for 1 hour.
Let dry for an hour. The surface resistance of the resulting dark green translucent film was measured to be 5×10 ⁵ ohms (two probes 0.5 cm apart). Example 10 The stability of the polypyrrole/nylon fiber of Example 4 was tested by examining the resistance per length of a single fiber under various conditions. Table 1 shows the results.

[Table] Example 11 Three polyvinyl alcohol particles (about 1 mm diameter)
Suspend in methanol containing iron chloride hydrate (0.1 M) for 30 minutes, collect by filtration, and wash with methanol. The resulting yellow particles were dissolved in acetonitrile containing pyrrole (10%).
After being suspended for a minute, the particles turn black. The particles are collected, washed with acetonitrile, and then dried under vacuum overnight. When compressed at 4000 psi, the particles exhibit a volume conductivity of approximately 5 x 10 ^-4 S/cm. Example 12 A solution of polycarbonate (0.25 g) in methylene chloride (2 ml) containing 10% by volume of pyrrole is spread on a glass slide as in Example 1. The resulting thin film is immersed in the iron trichloride solution of Example 1 for 1 hour. The resulting gray translucent film is peeled off from the glass surface, washed with water and dried under vacuum. The specific electrical conductivity of this film was measured to be 2×10 ^-2 S/cm.

Claims (1)

[Claims] 1. (a) A cyclic monomer selected from pyrrole, aniline and substituted analogs thereof is diffused into a non-porous polymer or (b) co-dissolving the impregnated polymer with a non-porous polymer in a solvent for them and evaporating the solvent; trivalent iron compounds, tetravalent cerium compounds, hexavalent molybdenum, tungsten or chromium, which are oxidizing agents capable of reacting with the formula monomer and converting it into electrically conductive polymeric oxidation products. compound, divalent copper compounds, monovalent silver compounds, nitrites, quinones, peroxides and peracids. A method of imparting electrical conductivity to a surface layer of up to 1 mm in depth of this non-porous polymer by impregnating it with an electrically conductive polymer. 2. The method of claim 1, wherein a catalytic amount of at least one acid is added to the oxidizing agent for contacting the oxidative polymerization reaction. 3. The method according to claim 1, wherein the cyclic monomer is pyrrole and the oxidizing agent is iron trichloride. 4. The method according to claim 1, wherein the cyclic monomer is aniline and the oxidizing agent is ammonium persulfate. 5. The method according to claim 1, wherein the parent polymer is one selected from the group consisting of polyamide, polyvinyl chloride, polycarbonate, polyvinyl acetate, and polyurethane. 6. The method according to claim 1, wherein the parent polymer is present as a fiber, woven fabric, or thin film.