JP2004331960A - Composition containing polyanilines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition containing polyanilines in which the polyanilines are homogeneously dispersed in water or water-soluble solvents, and imparts a film with high conductivity, water resistance, strength and flexibility by coating. <P>SOLUTION: The composition containing the polyanilines comprises the polyanilines, and an emulsion polymer, wherein the emulsion polymer contains vinylpyrrolidones and a monomer having acid group as essential components. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polyaniline-containing composition in which polyaniline is uniformly dispersed in water or a water-soluble solvent.

  Among various conductive polymers, polyaniline has good stability in air, and applications in various fields are being studied. Typical application examples include a positive electrode of a secondary battery, a solid electrolyte capacitor, an antistatic material, a rust preventive, a transparent conductive film, and an electromagnetic wave shielding material.

  In many of these applications, polyaniline is used by coating various materials. In this case, the coated coating film is required to have film forming properties, strength, flexibility, and the like as the coating film in addition to conductivity, which is a characteristic derived from polyaniline.

  However, in general, polyaniline has remarkably low solubility and dispersibility in water and water-soluble solvents.When used as a coating agent, polyaniline can be prepared only with a low content of polyaniline and has insufficient conductivity or is forced to be used. In the case where polyaniline is dispersed, the dispersion state is poor, so that the film formability as a uniform coating film is poor, and the strength and flexibility of the coating film itself are insufficient.

  In order to solve these problems, a method of obtaining a polyaniline-containing composition having excellent dispersibility by oxidative polymerization of an aniline monomer in the presence of an emulsion polymer, and a method of mixing a doped polyaniline and an emulsion polymer are known. It has been proposed (for example, see Patent Documents 1 and 2).

However, in the case of the above method, the oxidative polymerization of aniline performed in the presence of the polymer emulsion is very slow, and only a low molecular weight polyaniline can be obtained. A large amount of dopant is required to prepare a doped polyaniline that forms a stable mixture with the coalescence, and there is a problem that the water resistance of a coating film made of the polyaniline-containing composition is reduced.
JP-A-64-69621 JP 2000-256617 A

  Therefore, in the present invention, polyaniline is uniformly dispersed in water or a water-soluble solvent, shows high conductivity by forming a film, and provides a coating film excellent in water resistance, strength and flexibility. It is an object to provide a class-containing composition.

  The polyaniline-containing composition of the present invention is a composition containing a polyaniline and an emulsion polymer, and the emulsion polymer contains, as constituent monomers, a vinylpyrrolidone and a monomer having an acid group. It has a gist where it is considered an essential component.

  When the proportion of the vinylpyrrolidone in the above-mentioned constituent monomer is in the range of 10% by mass to 70% by mass, the dispersibility of the polyaniline is further improved, and a higher conductive coating film is formed by forming a film. This is a preferred embodiment because it can be obtained.

  Since the polyaniline-containing composition of the present invention has the above-described composition, the polyaniline is uniformly dispersed, so that the composition exhibits high conductivity by forming a film, and has sufficient water resistance, strength, and flexibility. Give the membrane.

  The present inventors have conducted intensive studies on a polyaniline-containing composition in which polyaniline is uniformly dispersed in water or a water-soluble solvent, and as a result, the composition containing the polyaniline and the emulsion polymer has a low emulsion weight. By using a vinylpyrrolidone and a monomer having an acid group as essential components as constituent monomers of the union, a composition in which polyanilines are uniformly dispersed can be obtained, and the composition is formed into a film. Then, they found that a coating film having high conductivity and excellent in water resistance, strength, and flexibility was obtained, and the present invention was conceived.

  As the polyaniline in the present invention, general emeraldine-type polyaniline is preferably used. The emeraldine-type polyanilines include those containing, as a repeating unit, a basic skeleton in which a reduced unit (phenylenediamine skeleton) and an oxidized unit (quinone imine skeleton) are present at a molar ratio of 1: 1.

  The polyaniline used in the present invention may be produced by a known method, or a commercially available product may be used as it is.

  As the polyaniline used in the present invention, besides the above emeraldine-type polyaniline, those in which an aromatic ring in the polyaniline skeleton is o- or m-substituted can also be used. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a carboxyester group having 1 to 20 carbon atoms, a cyano group, an aryl group, a sulfone group, and a halogen group.

  The weight average molecular weight (Mw) of the polyaniline is preferably 2,000 or more in terms of polyethylene oxide by GPC. If the weight average molecular weight is less than 2,000, the conductivity of the coating film composed of the polyaniline-containing composition may be low. Conversely, when the weight average molecular weight exceeds 300,000, the dispersibility of the polyaniline decreases, and the strength and flexibility of the coating film may deteriorate. The weight average molecular weight is more preferably in the range of 3,000 to 200,000, and most preferably in the range of 5,000 to 100,000.

  The content of the polyaniline in the polyaniline-containing composition of the present invention is preferably in the range of 0.02 to 10% by mass. If the content is less than 0.02% by mass, the conductivity of the coating film composed of the polyaniline-containing composition may be lowered. If the content exceeds 10% by mass, the dispersibility of the polyaniline becomes poor. There is a possibility that the strength and flexibility of the coating film composed of the composition may be reduced. The content is more preferably in the range of 0.1 to 8% by mass, and most preferably in the range of 0.5 to 6% by mass.

  The content of the emulsion polymer in the polyaniline-containing composition of the present invention is preferably in the range of 10 to 60% by mass. If the content is less than 10% by mass, the film-forming property of the polyaniline-containing composition may be deteriorated, and a uniform coating film may not be obtained. If the content exceeds 60% by mass, the viscosity of the polyaniline-containing composition becomes high. The handling workability may be reduced. The content is more preferably in the range of 15 to 50% by mass, and most preferably in the range of 20 to 40% by mass.

  The emulsion polymer of the present invention contains vinylpyrrolidones and monomers having an acid group as essential components.

  Examples of the vinylpyrrolidones include N-vinylpyrrolidone and N-vinyl-5-methyl-2-pyrrolidone.

  The amount of the vinylpyrrolidone used in the constituent monomer is preferably in the range of 10 to 70% by mass. If the amount is less than 10% by mass, the dispersibility of the polyaniline may decrease, and if it exceeds 70% by mass, the water resistance of the coating film composed of the polyaniline-containing composition may decrease. The use amount is more preferably in the range of 15 to 50% by mass. Most preferably, it is in the range of 20 to 40% by mass.

  The monomer having an acid group in the present invention functions as a dopant for doping polyanilines to exhibit conductivity. As the monomer having an acid group, a monomer having a carboxyl group, a monomer having a sulfone group, and a monomer having a phosphoric acid group can be preferably used. Specifically, (meth) acrylic acid , 2-acrylamido-2-methylpropanesulfonic acid, methallylsulfonic acid, 3-sulfopropyl (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, and the like.

  The preferred lower limit of the amount of the monomer having an acid group in the constituent monomers of the emulsion polymer used in the present invention is 0.1% by mass, and the preferred upper limit is 40% by mass. If the amount is less than 0.1% by mass, the conductivity of the coating film using the polyaniline-containing composition may be low because the doping efficiency of the polyaniline is low. The water resistance of the coating film using the composition may be reduced. The amount is more preferably at least 0.5% by mass, most preferably at least 1.0% by mass. The use amount is more preferably 30% by mass or less, and most preferably 20% by mass or less.

  In the emulsion polymer, other monomers besides vinylpyrrolidones and monomers having an acid group can be used as constituent monomers. The types and amounts of the other monomers may be appropriately selected depending on the physical properties required for the coating film composed of the polyaniline-containing composition.

  Examples of the other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, propyl (meth) acrylate, and cyclohexyl. (Meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, phenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate , Hydroxybutyl (meth) acrylate, ethylene glycol di (meth) acrylate, dithylene glycol di (meth) acrylate, triethylene glycol di (meth) (Meth) acrylates such as acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, (meth) acrylamide, methylenebis (meth) acrylamide, and styrene , Α-methylstyrene, vinyltoluene, divinylbenzene and the like.

  The amount of the other monomers used in the constituent monomers of the emulsion polymer used in the present invention is preferably in the range of 10 to 80% by mass. If the amount is less than 10% by mass, the water resistance of the coating film using the polyaniline-containing composition may be reduced. If the amount is more than 80% by mass, the dispersibility of the polyaniline is reduced and the polyaniline-containing composition is reduced. There is a possibility that the conductivity of the resulting coating film may decrease. The amount is more preferably in the range of 20 to 70% by mass, and most preferably in the range of 30 to 60% by mass.

  As a method for preparing the polyaniline-containing composition according to the present invention, a method in which polyaniline is previously dissolved or dispersed in a monomer mixture of an emulsion polymer containing vinylpyrrolidone as an essential component, and then emulsion-polymerized. preferable. If this method is adopted, the dispersibility of the polyaniline is improved, and a polyaniline-containing composition that gives a coating film with higher conductivity is easily obtained.

  When dissolving or dispersing the polyaniline in the monomer mixture of the emulsion polymer containing vinylpyrrolidone as an essential component, an undoped polyaniline that has not been doped in advance is used as the polyaniline before dissolution or dispersion. Is preferred. That is, doping occurs when the polyaniline is dissolved or dispersed in the monomer mixture of the emulsion polymer, and the polyaniline changes from insulating to conductive.

  When dissolving or dispersing as described above, it is preferable to dissolve or disperse with stirring using a device capable of high-speed rotation and stirring such as a homogenizer or a homomixer.

  For the emulsion polymerization for obtaining the above emulsion polymer, a general emulsion polymerization method can be employed, and examples thereof include a monomer addition method, a monomer dropping method, a pre-emulsion method, a power feed method, and a seed method. And a monomer multi-stage addition method.

  Reaction conditions such as a reaction temperature and a reaction time in the polymerization reaction may be appropriately set. The polymerization reaction is preferably performed in a nitrogen atmosphere. At that time, a chain transfer agent may be added to adjust the average molecular weight.

  As the emulsifier used in the emulsion polymerization preferably employed in the present invention, a nonionic emulsifier capable of stably retaining micelles is preferable, and among them, an emulsifier having an aromatic ring in the molecular skeleton is preferably a polyaniline. It is suitable as an emulsifier having a high affinity.

  Examples of the emulsifier include "Nonipol series", "Eleminol SCZ-35", "Eleminol STN-6", "Selenium STN-8", "Same STN-13", "Same STN-20", and "Same as STN-20". STN-45 "(trade name, manufactured by Sanyo Kasei Co., Ltd.)," Emulgen A-60 "," trade name A-66 "," trade name A-90 "(trade name, manufactured by Kao Corporation)," Neugen EA -157 "," EA-167 "," EA-177 "," Aquaron RN-10 "," RN-20 "," RN-30 "," RN-50 "(the above, (Trade name, manufactured by Issei Pharmaceutical Co.).

  As the emulsifier, those having an HLB (abbreviation of Hydrophil-Lipophile Balance) of 12 to 18 are preferable in order to maintain the stability of micelles.

  The amount of the emulsifier used is preferably in the range of 1 to 15 parts by mass with respect to 100 parts by mass of the constituent monomer mixture. If the amount is less than 1 part by mass, the stability during emulsion polymerization may be insufficient, and if it exceeds 15 parts by mass, the water resistance of the coating film composed of the polyaniline-containing composition may be reduced. The amount is more preferably in the range of 3 to 12 parts by mass, most preferably in the range of 5 to 10 parts by mass.

  As the polymerization initiator used in the above emulsion polymerization, an azo-based polymerization initiator which is less likely to oxidize polyanilines is preferable. Examples of the azo-based polymerization initiator include water-soluble azo compounds such as 2,2′-azobis (2-aminodinopropane) dihydrochloride and 4,4′-azobis (4-cyanopentanoic acid). Can be

  The amount of the polymerization initiator used is preferably in the range of 0.1 to 5 parts by mass with respect to 100 parts by mass of the constituent monomer mixture. When the amount is less than 0.1 part by mass, the emulsion polymerization becomes difficult to proceed, the monomer remains, and the strength and flexibility of the coating film composed of the polyaniline-containing composition may be reduced. If it exceeds, the stability during emulsion polymerization may be deteriorated. The amount is more preferably in the range of 0.5 to 3 parts by mass, most preferably in the range of 0.7 to 2 parts by mass.

  The polyaniline-containing composition of the present invention may contain other compounds and auxiliary materials as necessary.

  Examples of the other compounds and auxiliary materials include an antioxidant, an ultraviolet absorber, an ultraviolet stabilizer, a plasticizer, a leveling agent, an anti-cissing agent, and a solvent. The amount of these other compounds and auxiliary materials is not particularly limited as long as the effects of the present invention are not impaired. preferable.

  Hereinafter, the present invention will be described specifically with reference to examples, but the scope of the present invention is not limited to these examples. Unless otherwise noted, "%" means "% by mass" and "parts" means "parts by mass".

Example 1
As polyanilines, 10 parts of polyaniline (Emeraldine base, trade name "PANIPOL PA" manufactured by Panipol) were uniformly dissolved in 20 parts of N-vinylpyrrolidone as vinylpyrrolidones to obtain a blue-violet polyaniline solution. This solution was added dropwise to a mixed solution of 20 parts of styrene, 10 parts of butyl acrylate, and 10 parts of acrylic acid as a monomer having an acid group while stirring with a homogenizer, and a dark green monodisperse in which polyaniline was uniformly dispersed was obtained. A body mixture was obtained.

  A reactor equipped with a thermometer, a cooling pipe, a nitrogen introduction pipe, a dropping funnel and a stirrer was charged with 140 parts of ion-exchanged water and 1.8 parts of a surfactant (trade name "Nonipol 200" manufactured by Sanyo Chemical Industries, Ltd.) The mixture was stirred and dissolved while blowing nitrogen gas. The monomer mixture was placed in a dropping funnel, and 1/10 of the mixture was dropped into the reactor. Subsequently, 12 parts of a 5% aqueous solution of 2,2'-azobis (2-amidinopropane) dihydrochloride was added. After a polymerization reaction at 70 ° C. for 30 minutes, the remaining monomer mixture was added dropwise over 2 hours. After completion of the dropwise addition, a polymerization reaction was further performed at the same temperature for 1 hour to obtain a polyaniline-containing composition (1) according to the present invention having a nonvolatile content of 29% and a polyaniline content of 4.5%.

Example 2
7 parts of polyaniline was uniformly dissolved in 5 parts of N-vinylpyrrolidone to obtain a blue-violet polyaniline solution. This solution was added dropwise to a mixture of 20 parts of styrene, 10 parts of butyl acrylate, and 10 parts of acrylic acid while stirring with a homogenizer to obtain a dark green monomer mixture in which polyaniline was uniformly dispersed.

  Subsequently, an emulsion polymerization reaction was carried out in the same manner as in Example 1 to obtain a polyaniline-containing composition (2) according to the present invention having a nonvolatile content of 25% and a polyaniline content of 1.0%.

Example 3
7 parts of polyaniline was uniformly dissolved in 20 parts of N-vinylpyrrolidone to obtain a blue-violet polyaniline solution. This solution was added dropwise to a mixed solution of 20 parts of styrene, 10 parts of butyl acrylate, and 5 parts of 2-acrylamido-2-methylpropanesulfonic acid as a monomer having an acid group while stirring with a homogenizer to obtain polyaniline. Was uniformly dispersed to obtain a dark green monomer mixture.

  Subsequently, an emulsion polymerization reaction was carried out in the same manner as in Example 1 to obtain a polyaniline-containing composition (3) according to the present invention having a nonvolatile content of 30% and a polyaniline content of 3.2%.

Comparative Example 1
10 parts of polyaniline was uniformly dissolved in 20 parts of N-vinylpyrrolidone to obtain a blue-violet polyaniline solution. This solution was added dropwise to a mixed solution of 20 parts of styrene and 10 parts of butyl acrylate while stirring with a homogenizer to obtain a blue-violet monomer mixture in which polyaniline was uniformly dispersed. In this case, since no monomer having an acid group is used, the polyaniline remains undoped and insulating.

  An emulsion polymerization reaction was carried out in the same manner as in Example 1, but polyaniline was almost completely precipitated, and a comparative polyaniline-containing composition (1) having a nonvolatile content of 25% and a polyaniline content of less than 0.02% was obtained.

Reference Example 1
A mixture of 20 parts of styrene, 10 parts of butyl acrylate and 10 parts of acrylic acid was put into a dropping funnel, and an emulsion polymerization reaction was carried out in the same manner as in Example 1 to obtain an emulsion composition (1) having a nonvolatile content of 26%. .

Comparative Example 2
In 150 parts of the emulsion composition (1) synthesized in Reference Example 1, 10 parts of 12N hydrochloric acid and 4.65 parts of aniline were dissolved. In addition, an oxidizing agent aqueous solution in which 11.4 parts of ammonium persulfate was dissolved in 100 parts of ion-exchanged water was prepared. The two solutions were cooled to 5 ° C., mixed, and reacted with stirring for 8 hours to obtain a comparative polyaniline-containing composition (2) having a nonvolatile content of 23% and a polyaniline content of 1.3%. Was. The reaction rate of the aniphosphorylation polymerization in this reaction was 80%.

Reference Example 2
10 parts of p-toluenesulfonic acid were dissolved in 150 parts of ion-exchanged water, and 1.5 parts of sulfuric acid and 2.5 parts of aniline were added thereto, and the mixture was cooled to 0C. Further, a solution in which 5.5 parts of ammonium persulfate was dissolved in 50 parts of ion-exchanged water was cooled to 0 ° C. in advance, and added dropwise over 15 minutes. After stirring at 0 ° C. for 20 hours, the mixture was concentrated by ultrafiltration to obtain a polyaniline solution having a nonvolatile content of 38% and a polyaniline content of 5.0%.

  Further, 100 parts of this polyaniline solution and 100 parts of the emulsion composition (1) obtained in Reference Example 1 were mixed to obtain a comparative polyaniline-containing composition (3) having a nonvolatile content of 32% and a polyaniline content of 2.5%. Got.

Performance Evaluation Using the polyaniline-containing compositions (1) to (3) obtained in Examples 1 to 3 and the comparative polyaniline-containing compositions (1) to (3) obtained in Comparative Examples 1 to 3, The method was evaluated for performance. Table 1 shows the evaluation results.

"Evaluation test method"
(A) Surface resistance value The test polyaniline-containing composition was applied on a glass substrate with a bar coater so that the dry thickness was about 2 μm, and then dried at 120 ° C. for 30 minutes to form a 2 μm-thick coating film. The surface resistance of the formed film was measured in accordance with JIS-K6911.

(B) Water resistance A test aniline-containing composition was applied on an aluminum substrate that had been subjected to a chromate treatment to a dry thickness of about 2 μm using a bar coater, and then dried at 120 ° C. for 30 minutes. A coating film having a thickness of 2 μm was formed. After the test plate on which the coating film was formed was immersed in ion-exchanged water at 25 ° C. ± 3 for 3 days, the appearance was visually evaluated based on the following criteria.
…: No abnormality △: partial blistering is observed x: tearing is observed in the coating film.

(C) Pencil hardness measurement A test aniline-containing composition was applied on a chromate-treated aluminum substrate by a bar coater so as to have a dry thickness of about 2 μm, and then dried at 120 ° C. for 30 minutes. A coating film having a thickness of 2 μm was formed, and the pencil hardness of the coating film was measured according to JIS-K6911.

  As is clear from Table 1 above, the polyaniline-containing compositions of Examples 1 to 3 can uniformly form a film because polyaniline is uniformly dispersed, and the formed film shows high conductivity. Not only that, the coating film has sufficient performance in terms of water resistance, strength and flexibility.

  On the other hand, the polyaniline-containing composition of Comparative Example 1 has a low concentration of polyaniline and has almost no conductivity because it is not doped. Further, the polyaniline-containing composition of Comparative Example 2 had a poor dispersion state of polyaniline and a low degree of polymerization of polyaniline, so that the conductivity of the formed coating film was low. The water resistance, strength and flexibility of the film were also insufficient. In Comparative Example 3, the conductivity of the coating film was good because a large amount of dopant was used, but the water resistance, strength, and flexibility of the coating film were insufficient.

Claims (2)

  A composition containing a polyaniline and an emulsion polymer, wherein the emulsion polymer has, as constituent monomers, a vinylpyrrolidone and a monomer having an acid group as essential components. A polyaniline-containing composition.   The polyaniline-containing composition according to claim 1, wherein the proportion of the vinylpyrrolidone in the constituent monomer is in the range of 10% by mass to 70% by mass.