JP5044161B2 - Triphenylamine derivative and electrophotographic photoreceptor using the same - Google Patents

Description

  The present invention relates to an electrophotographic photoreceptor containing a charge transport agent excellent in solubility in an organic solvent and compatibility with a binder resin used for forming a photosensitive layer.

  In an image forming apparatus such as a laser printer, a copying machine, or a facsimile, an organic photoreceptor having sensitivity suitable for a wavelength region of a light source used in the apparatus is used. This organic photoconductor is easier to manufacture than conventional inorganic photoconductors, and there are various options for constituent materials of the photoconductor such as a charge transport agent, a charge generator, and a binder resin. Widely used because of its high cost.

  The organic photoreceptor includes a single-layer photoreceptor in which a charge generator is dispersed in a photosensitive layer containing a charge transport agent, a charge generation layer containing a charge generator, and a charge transport layer containing a charge transport agent. There are laminated type photoconductors in which are separated and laminated. In any of the above photoreceptors, in order to improve the sensitivity characteristic, it is required to use a charge transport agent having a high charge transport property. Therefore, various charge transport agents have been proposed, and Patent Document 1 discloses triphenylamine derivatives represented by the following formulas HT-7 and HT-8.

  However, although the triphenylamine derivatives disclosed in the above publications are generally excellent in charge transporting properties, they have low solubility in organic solvents and low compatibility with binder resins used for forming photosensitive layers. It is not uniformly dispersed therein, and charge transfer is unlikely to occur. For this reason, the triphenylamine derivative itself has a high charge mobility, but when it is used as a charge transport agent for a photoreceptor, the characteristics cannot be fully exhibited, and the photosensitivity is not expected for long-term use. There is a problem that the residual potential of the body becomes high and the photosensitivity becomes insufficient.

JP 2005-289877 A

  An object of the present invention is to provide an electrophotographic photoreceptor excellent in sensitivity characteristics by using a charge transfer agent excellent in solubility in an organic solvent and compatibility with a binder resin used for forming a photosensitive layer.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor, according to the novel triphenylamine derivative represented by the following general formula (1), exhibits solubility in organic solvents and compatibility with binder resins. The present inventors have found a new fact that it can be remarkably improved and that it is possible to obtain a high-sensitivity electrophotographic photosensitive member by preventing the precipitation of crystals in the photosensitive layer, and the present invention has been completed.

（式中、Ｒ_aはフェニル基を示し、Ｒ₁からＲ₁₂は、同一または異なる基であって、水素原子、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、フェノキシ基、炭素数６〜２０のアラルキル基、または炭素数６〜２０のアリール基を示し、アルキル基、アラルキル基、またはアリール基は置換基を有していてもよい。ｎ１およびｎ２は０または１の整数を示す。）
（２）少なくとも電荷発生剤および電荷輸送剤を含有する感光層を備えた電子写真感光体であって、前記電荷輸送剤は（１）に記載の一般式（１）で表されるトリフェニルアミン誘導体からなることを特徴とする電子写真感光体。 That is, the triphenylamine derivative according to the present invention and the electrophotographic photoreceptor using the same have the following characteristics.
(1) A triphenylamine derivative represented by the following general formula (1).

(In the formula, R _a represents a phenyl group, and R ₁ to R ₁₂ are the same or different groups, and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenoxy group. , An aralkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, wherein the alkyl group, aralkyl group, or aryl group may have a substituent, and n1 and n2 are 0 or 1 Indicates an integer.)
(2) An electrophotographic photosensitive member provided with a photosensitive layer containing at least a charge generating agent and a charge transporting agent, wherein the charge transporting agent is represented by the general formula (1) described in (1) An electrophotographic photoreceptor comprising a derivative.

  According to the charge transfer agent comprising the triphenylamine derivative represented by the general formula (1) of the present invention, the solubility in an organic solvent and the compatibility with a binder resin are remarkably improved, and crystals are precipitated in the photosensitive layer. Is prevented, and a highly sensitive electrophotographic photoreceptor can be obtained.

Hereinafter, embodiments of the present invention will be described in detail. The triphenylamine derivative according to the present invention is represented by the general formula (1) as described above. In the triphenylamine derivative (1) according to the present invention, the substituent Ra represents an optionally substituted aryl group having 6 to 20 carbon atoms, and R _{1 to} R ₁₂ are the same or different groups. , A hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a phenoxy group, an aralkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, an alkyl group and an aralkyl group The group or aryl group may have a substituent. n1 and n2 represent an integer of 0 or 1.

Examples of the alkyl group in R _{1 to} R ₁₂ include a methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, pentyl group, isopentyl group, C1-C6 alkyl groups, such as a neopentyl group and a hexyl group, are mentioned. Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, s-butoxy, t-butoxy, pentyloxy, isopentyloxy, neopentyloxy, hexyloxy and the like.
Examples of the aralkyl group in R _{1 to} R ₁₂ include benzyl, α-methylbenzyl, phenethyl, styryl, cinnamyl, 3-phenylpropyl, 4-phenylbutyl, 5-phenylpentyl, 6-phenylhexyl group and the like.
Examples of the aryl group in R _a and R _{1 to} R ₁₂ include aryl groups having 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, a tolyl group, a xylyl group, an anthryl group, and a phenanthryl group. The aryl group may have 1 to 3 substituents, and examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms.
Further, among R ₁ to R _12, it is preferable that at least one is an alkyl group having 1 to 6 carbon atoms. By having an alkyl group having 1 to 6 carbon atoms at a specific substitution position, it is possible to effectively have a twisted structure in the molecule of the charge transport agent, and the solubility in the compound binder resin is improved. Mobility can be increased.

  The triphenylamine derivative represented by the formula (1) is a third substituent in which two substituents substituted on a nitrogen atom each have the same or different double-bonded aryl group, and the nitrogen atom is substituted. Has an aryl group in the ortho position. When the third substituent has an aryl group in the ortho position with respect to the nitrogen atom, it is considered that due to the steric effect, the solubility in an organic solvent and the compatibility with the binder resin are excellent.

  Examples of the triphenylamine derivative represented by the above formula (1) according to the present invention include HT-1 to 6 shown below. However, the triphenylamine derivative of the formula (1) that can be used as a charge transfer agent in the present invention is not limited to these. In addition, Ph means a phenyl group.

(Synthesis method)
Any triphenylamine derivative contained in the formula (1) in the present invention can be synthesized by a known production method. For example, HT-6 can be obtained by the following method using a Wittig reaction and a coupling reaction. That is, first, compound (3) which is a phosphite derivative is subjected to a substitution reaction at a temperature of 0 to 10 ° C., dry THF (tetrahydrofuran) and sodium methoxide are added, and the mixture is stirred for 20 to 50 minutes. To do. Next, the compound (4) which is an aldehyde derivative dissolved in dry THF is added to the obtained reaction solution, and the mixture is stirred at room temperature for 10 to 15 hours. The resulting reaction solution can be extracted with toluene or the like to obtain compound (5).

同様にして、亜リン酸エステル誘導体である化合物（７）を温度０〜１０℃のもとで置換反応を行い、乾燥ＴＨＦ（テトラヒドロフラン）とナトリウムメトキシドとを加えて、２０〜５０分混合攪拌する。次に、得られた反応液に、乾燥ＴＨＦに溶解させたアルデヒド誘導体である化合物（１１）を加え、室温で１０〜１５時間攪拌する。得られた反応液をトルエンなどで抽出して化合物（８）を得ることができる。

Similarly, the compound (7) which is a phosphite derivative is subjected to a substitution reaction at a temperature of 0 to 10 ° C., dry THF (tetrahydrofuran) and sodium methoxide are added, and the mixture is stirred for 20 to 50 minutes. To do. Next, the compound (11) which is an aldehyde derivative dissolved in dry THF is added to the obtained reaction solution, and the mixture is stirred at room temperature for 10 to 15 hours. The resulting reaction solution can be extracted with toluene or the like to obtain compound (8).

次に、得られた化合物（５）と化合物（９）とを、下記の反応式によりカップリング反応させる。すなわち、Ｐｄ触媒の存在下でアニリン誘導体とクロロベンゼンとのカップリング反応により得られる化合物（９）と前記化合物（５）とをｏ−キシレンに加えて、Ｐｄ触媒の存在下で置換反応を行い、１００〜１３０℃で２〜４時間攪拌する。その後室温まで冷却し、得られた反応液をトルエンなどで抽出して化合物（１０）を得ることができる。

Next, the obtained compound (5) and compound (9) are subjected to a coupling reaction by the following reaction formula. That is, the compound (9) obtained by a coupling reaction of an aniline derivative and chlorobenzene in the presence of a Pd catalyst and the compound (5) are added to o-xylene, and a substitution reaction is performed in the presence of a Pd catalyst. Stir at 100-130 ° C. for 2-4 hours. Thereafter, the mixture is cooled to room temperature, and the resulting reaction solution is extracted with toluene or the like to obtain compound (10).

さらに、同様にして、得られた化合物（１０）と化合物（８）とを、下記の反応式によりカップリング反応させる。すなわち、化合物（１０）と前記化合物（８）とをｏ−キシレンに加えて、Ｐｄ触媒の存在下で置換反応を行い、１００〜１３０℃で２〜４時間攪拌する。その後室温まで冷却し、得られた反応液をトルエンなどで抽出し、本発明にかかるＨＴ−６が得られる。

Further, similarly, the obtained compound (10) and compound (8) are subjected to a coupling reaction according to the following reaction formula. That is, the compound (10) and the compound (8) are added to o-xylene, a substitution reaction is performed in the presence of a Pd catalyst, and the mixture is stirred at 100 to 130 ° C. for 2 to 4 hours. Thereafter, it is cooled to room temperature, and the resulting reaction solution is extracted with toluene or the like to obtain HT-6 according to the present invention.

本発明における式（１）に含まれる他の化合物も、前記化合物（３）、（４）、（７）および（１１）を、所望の基を有する化合物に代えることにより、前記と同様にして合成することができる。

Other compounds included in the formula (1) in the present invention can be prepared in the same manner as described above by replacing the compounds (3), (4), (7) and (11) with compounds having a desired group. Can be synthesized.

  As described above, the electrophotographic photoreceptor of the present invention contains a charge transport agent comprising a triphenylamine derivative contained in the above formula (1) in the photosensitive layer.

The photosensitive layer is composed of a single layer type photoreceptor in which a charge generator and a charge transport agent are mixed in the same layer, a layer containing a charge generator, and a layer containing a charge transport agent. Each photosensitive layer is obtained by dissolving and dispersing each component such as a charge generating agent and a charge transporting agent in a solvent together with a binder resin and the like. It is formed by applying and drying the resulting coating solution on a conductive substrate.
As described above, the electrophotographic photoreceptor of the present invention contains a compound contained in the formula (1) having good solubility in a solvent and high charge transportability, and therefore, compared with a conventional electrophotographic photoreceptor. And high sensitivity. Moreover, according to the electrophotographic photosensitive member of the present invention, since the compatibility between the compound contained in the formula (1) and the binder resin is good, the long-term stability of the photosensitive layer is improved.

(Charge generator)
Next, examples of the charge generating agent according to the present invention include metal-free phthalocyanine, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, α-titanyl phthalocyanine, Y-titanyl phthalocyanine, and phthalocyanine pigments such as V-hydroxygallium phthalocyanine, and perylene pigments. Bisazo pigment, diketopyrrolopyrrole pigment, metal-free naphthalocyanine pigment, metal naphthalocyanine pigment, squaraine pigment, trisazo pigment, indigo pigment, azurenium pigment, cyanine pigment, pyrylium pigment, ansanthrone pigment, triphenylmethane pigment, Organic photoconductors such as selenium pigments, toluidine pigments, pyrazoline pigments, quinacridone pigments, selenium, selenium-tellurium, selenium-arsenic, cadmium sulfide, amorphous silicon Inorganic photoconductive material and the like such emissions. These charge generating agents may be used alone or in combination of two or more.

  In the present invention, a phthalocyanine pigment, particularly a metal-free phthalocyanine (for example, X-type metal-free phthalocyanine), titanyl phthalocyanine, hydroxygallium phthalocyanine and chlorogallium phthalocyanine is used as a charge generator. In view of the electrical characteristics of the photoreceptor when red or infrared light having a wavelength of 650 nm or more is used as an exposure light source, it is preferable.

(Hole transport agent)
The charge transport agent used in the electrophotographic photosensitive member of the present invention is a hole transport agent and is composed of a compound included in the formula (1).
In the electrophotographic photoreceptor of the present invention, various conventionally known hole transport agents may be contained in the photosensitive layer in combination with the compound (1). Examples of such other hole transporting agents include bisstilbenediamine derivatives, bistriphenylamine derivatives, triphenylaminostyryl derivatives, stilbeneamine-hydrazone derivatives, and the like.

(Electron transfer agent)
Examples of the electron transporting agent include diphenoquinone derivatives, benzoquinone derivatives, naphthoquinone derivatives, anthraquinone derivatives, malononitrile derivatives, thiopyran derivatives, thioxanthone derivatives (2,4,8-trinitrothioxanthone, etc.), fluorenone derivatives (3,4,5,7). -Tetranitro-9-fluorenone derivatives, etc.), anthracene derivatives, acridine derivatives, dinitrobenzene, dinitroanthracene, dinitroacridine, succinic anhydride derivatives, maleic anhydride derivatives, dibromomaleic anhydride derivatives, etc. Can be mentioned.

(Binder resin)
In the electrophotographic photoreceptor of the present invention, conventionally known various resins can be adopted as the binder resin for forming a layer containing each component such as a charge generator and a charge transport agent. Among them, the use of at least one resin selected from the group consisting of polycarbonate, polyester, polyarylate, polystyrene, and polymethacrylic acid ester as the binder resin is the compound represented by the above formula (1) according to the present invention. From the standpoint of further improving the compatibility, and the properties such as the strength and abrasion resistance of the photosensitive layer. Moreover, the binder resin exemplified above is excellent in compatibility with the charge generating agent and the charge transport agent, and does not have a site in the molecule that interferes with the charge transport property of the charge transport agent. Therefore, by using such a binder resin, an electrophotographic photosensitive member with higher sensitivity can be obtained.

(Dispersion medium)
As a dispersion medium used for preparing a coating solution for forming a photosensitive layer by dispersing and dissolving the charge generating agent, hole transporting agent, electron transporting agent, binder resin and the like exemplified above, a coating solution for forming a photosensitive layer is used. Various organic solvents conventionally used can be used. Specifically, alcohols such as methanol, ethanol, isopropanol and butanol; aliphatic hydrocarbons such as n-hexane, octane and cyclohexane; aromatic hydrocarbons such as benzene, toluene and xylene; dichloromethane, dichloroethane and chloroform , Halogenated hydrocarbons such as carbon tetrachloride and chlorobenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, dioxane, dioxolane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; ketones such as acetone, methyl ethyl ketone and cyclohexanone; ethyl acetate and methyl acetate And esters such as dimethylformaldehyde, dimethylformamide, and dimethyl sulfoxide.

  In addition, although not limited thereto, tetrahydrofuran, dioxane, dioxolane, cyclohexanone, among various organic solvents, are preferable for stably dispersing each component such as a charge generator, a charge transport agent, and a binder resin. It is preferable to use at least one organic solvent selected from the group consisting of toluene, xylene, dichloromethane, dichloroethane and chlorobenzene.

(Additive)
In the coating solution for forming the photosensitive layer, in addition to the above-mentioned components, various conventionally known additives such as an antioxidant, a radical scavenger, a singlet quencher are used as long as they do not adversely affect the electrophotographic characteristics. Deterioration inhibitors such as char and ultraviolet absorbers, softeners, plasticizers, surface modifiers, extenders, thickeners, dispersion stabilizers, waxes, acceptors, donors, and the like can be blended. In order to improve the sensitivity of the photosensitive layer, a known sensitizer such as terphenyl, halonaphthoquinones, and acenaphthylene may be used in combination with the charge generator. Further, a surfactant, a leveling agent or the like may be used in order to improve the dispersibility of the charge transport agent or charge generator and the smoothness of the photosensitive layer surface.

(Conductive substrate)
As the conductive substrate, various conductive materials can be used. For example, iron, aluminum, copper, tin, platinum, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel And a simple metal such as brass, a plastic material on which the above metal is deposited or laminated, and glass coated with aluminum iodide, tin oxide, indium oxide, or the like. The conductive substrate is used in the form of a drum or a sheet according to the structure of the image forming apparatus to be used. The conductive substrate preferably has sufficient mechanical strength.
The conductive substrate used in the present invention is not limited to this, but the surface thereof may be subjected to an oxide film treatment or a resin film treatment.

(Manufacture of single layer type electrophotographic photoreceptor)
The single-layer type electrophotographic photosensitive member includes a charge generator, the compound (1) of the present invention (hole transport agent), a binder resin, and an electron transport agent and the above additives as necessary. The photosensitive layer forming coating solution thus obtained is dispersed or dissolved in an appropriate dispersion medium, coated on a conductive substrate, and dried to form a photosensitive layer.

  In the photosensitive layer forming coating solution, the charge generating agent may be blended in an amount of 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight with respect to 100 parts by weight of the binder resin. What is necessary is just to mix | blend a hole transport agent in the ratio of 5-200 weight part with respect to 100 weight part of binder resin, Preferably it is 50-150 weight part. What is necessary is just to mix | blend an electron transport agent in the ratio of 5-200 weight part with respect to 100 weight part of binder resin, Preferably it is 10-100 weight part. In the case where the electron transport agent and the hole transport agent are used in combination, the total amount of the electron transport agent and the hole transport agent is 20 to 500 parts by weight, preferably 30 to 200 parts by weight with respect to 100 parts by weight of the binder resin. It is appropriate to do.

The thickness of the photosensitive layer obtained by applying the coating solution for forming the photosensitive layer is preferably set to 5 to 100 μm, particularly 10 to 50 μm.
When preparing a coating solution for forming a photosensitive layer, the above-exemplified charge generator, charge transport agent, insoluble azo pigment, binder resin, etc., together with an appropriate solvent, roll mill, ball mill, attritor, paint shaker, ultrasonic dispersion What is necessary is just to disperse and mix using well-known means, such as a machine.

(Manufacture of multilayer electrophotographic photoreceptors)
In the case of a laminated photoreceptor, a charge generator and a hole transport agent are mixed together with a suitable binder resin and solvent using a roll mill, ball mill, attritor, paint shaker, ultrasonic disperser, etc. What is necessary is just to prepare and apply | coat this dispersion liquid on an electroconductive base | substrate by a well-known means, and to make it dry. The thickness of each layer after drying is 0.01 to 5 μm, preferably 0.1 to 3 μm for the charge generation layer, and 2 to 100 μm, preferably 5 to 50 μm for the charge transport layer.

  In the charge generation layer of the multilayer photoconductor, the charge generation agent is preferably contained in an amount of 5 to 1000 parts by weight, particularly 30 to 500 parts by weight, based on 100 parts by weight of the binder resin. In the charge transport layer, the hole transport agent may be contained in an amount of 10 to 100 parts by weight, particularly 30 to 80 parts by weight with respect to 100 parts by weight of the binder resin. Moreover, when using together a positive hole transport agent and an electron transport agent, it is good to contain the total amount in the ratio of 10-500 weight part with respect to 100 weight part of binder resin, especially 30-200 weight part.

  Between the single layer type photosensitive layer or the multilayer type photosensitive layer and the conductive substrate, or between the charge generation layer and the charge transport layer constituting the multilayer type photosensitive layer, as long as the characteristics of the photosensitive member are not hindered. A layer, a barrier layer, or the like may be formed. A protective layer may be formed on the surface of the photosensitive layer.

  Hereinafter, the electrophotographic photosensitive member of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited only to the following Examples.

(Synthesis of hole transport agent)
(1) Synthesis of Compound (3) First, the compound represented by Formula (3) was synthesized according to the following reaction formula. That is, 20 g (0.124 mol) of 1-chloro-4-chloromethylbenzene and 30.0 g (0.18 mol) of triethyl phosphite were added to a 200 mL flask, heated at 180 ° C., and stirred for 8 hours. did. Then, after cooling to room temperature, excess phosphorous acid triethyl ester was distilled off under reduced pressure to obtain 29.3 g of a compound represented by the formula (3) (yield 90%).

(2) Synthesis of Compound (5) Next, the compound represented by the above formula (5) was synthesized according to the above reaction formula (R-1). That is, 13 g (0.049 mol) of the compound represented by the formula (3) was added to a 500 mL two-necked flask, and then substituted with argon gas, and 100 mL of dried tetrahydrofuran (THF) and 28% sodium were added. Methoxide (15.2 g, 0.079 mol) was added and stirred at 0 ° C. for 30 minutes. Next, 6.7 g (0.057 mol) of the compound represented by the formula (4) was dissolved in 300 mL of dry THF, and the mixture was stirred at room temperature for 12 hours. Thereafter, the reaction solution was poured into ion exchanged water and extracted with toluene, and the organic layer was washed 5 times with ion exchanged water. Next, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. Thereafter, the residue was purified with a toluene / methanol mixed solvent (toluene / methanol = 20 mL / 100 mL) to obtain a compound represented by the formula (5). Yield 9.3 g (yield 85%).

(3) Synthesis of Compound (7) Next, the compound represented by the formula (7) was synthesized according to the following reaction formula. That is, 13.6 g (0.098 mol) of compound (6) and 30.0 g (0.18 mol) of triethyl phosphite were added in a 200 mL flask, heated at 180 ° C., and stirred for 8 hours. Then, after cooling to room temperature, excess phosphorous acid triethyl ester was distilled off under reduced pressure to obtain 22.0 g of a compound represented by the formula (7) (yield 86%).

(4) Synthesis of Compound (8) Next, the compound represented by the formula (8) was synthesized according to the above reaction formula (R-2). That is, 12.5 g (0.049 mol) of the compound (7) obtained above was added into a 500 mL two-necked flask, and then substituted with argon gas and dried in 100 mL of tetrahydrofuran (THF), 28 % Sodium methoxide 15.2 g (0.079 mol) was added and stirred at 0 ° C. for 30 minutes. Next, 8.0 g (0.057 mol) of the compound represented by the formula (11) was dissolved in 300 mL of dry THF and added to this reaction solution, followed by stirring at room temperature for 12 hours. Thereafter, the reaction solution was poured into ion exchanged water and extracted with toluene, and the organic layer was washed 5 times with ion exchanged water. Next, the organic layer was dried over anhydrous sodium sulfate, and the solvent was distilled off. Thereafter, the residue was purified with a toluene / methanol mixed solvent (toluene / methanol = 20 mL / 100 mL) to obtain a compound represented by the formula (8). Yield 9.6 g (82% yield).

(5) Synthesis of Compound (10) Next, the compound represented by the formula (10) was synthesized according to the above reaction formula (R-3). That is, 18.3 g (0.0755 mol), (2-biphenyl) dicyclohexylphosphine (Pcy) 0.0662 g (0.000189 mol), tris (dibenzylideneacetone) 0.0864 g (0.0000944 mol) of palladium (Pd2 (dba) 3), 7.68 g (0.08 mol) of sodium t-butoxy (t-BuONa), 12.75 g (0.0755 mol) of compound (9), After adding purified o-xylene 500mL, argon gas substitution was performed and it stirred at 120 degreeC for 5 hours. Then, after cooling to room temperature, the organic layer was washed 3 times with ion exchange water. Next, the organic layer was dried over anhydrous sodium sulfate, further treated with activated clay, and xylene was distilled off under reduced pressure. Thereafter, the residue was purified by column chromatography (developing solvent: chloroform / hexane) to obtain 23.2 g of a compound represented by the formula (10) (yield 85%).

(6) Synthesis of HT-6 Finally, HT-6 was synthesized according to the above reaction formula (R-4). That is, in a 300 mL two-necked flask, 4.36 g (0.0181 mol) of compound (8), 0.0159 g (0.0000453 mol) of (2-biphenyl) dicyclohexylphosphine (Pcy), tris (dibenzylideneacetone) di 0.0207 g (0.0000226 mol) of palladium (Pd2 (dba) 3), 2.88 g (0.03 mol) of t-butoxy sodium (t-BuONa), 6.54 g (0.0181 mol) of compound (10), After adding 200 mL of purified o-xylene, argon gas substitution was performed, and the mixture was stirred at 120 ° C. for 3 hours. Then, after cooling to room temperature, the organic layer was washed 3 times with ion exchange water. Next, the organic layer was dried over anhydrous sodium sulfate, further treated with activated clay, and xylene was distilled off under reduced pressure. Thereafter, the residue was purified by column chromatography (developing solvent: chloroform / hexane) to obtain 8 g of the target compound (HT-6) (yield 78%).
In the triphenylamine derivative HT-6, R _{1 to} R ₁₀ of the triphenylamine derivative represented by the general formula (1) are hydrogen atoms, R ₁₁ is a methyl group, and a double bond extended group 2 Each of them is a compound in which n1 is 1 and n2 is 0, which is bonded to the phenyl group bonded to the nitrogen atom in the para position with respect to the nitrogen atom. The ¹ H-NMR spectrum of the triphenylamine derivative HT-6 is shown in FIG.

(Synthesis of HT-1)
In the synthesis of HT-6, HT-1 in the present invention is obtained by replacing the compound (4) with benzaldehyde and further replacing the compound (6) with a compound represented by the following formula (12). Was synthesized in the same manner as above.
In the triphenylamine derivative HT-1, R _{1 to} R ₅ and R _{7 to} R _{11 of the} triphenylamine derivative represented by the general formula (1) are hydrogen atoms, and any of two groups having a double bond extends. Is a compound in which n1 and n2 are both 0 bonded to the phenyl group bonded to the nitrogen atom in the para position with respect to the nitrogen atom.

(Synthesis of HT-2)
HT-2 was synthesized in the same manner as HT-6 by replacing the compound (6) with a compound represented by the following formula (13) in the synthesis of HT-6.
In the triphenylamine derivative HT-2, R _{1 to} R ₄ and R _{7 to} R _{10 of the} triphenylamine derivative represented by the general formula (1) are hydrogen atoms, and R ₅ and R ₁₁ are methyl groups. Both of the double-bonded groups are compounds in which n1 and n2 are both 0 bonded to the phenyl group bonded to the nitrogen atom in the para position with respect to the nitrogen atom. The ¹ H-NMR spectrum of the triphenylamine derivative HT-2 is shown in FIG.

(Synthesis of HT-3)
HT-3 in the present invention is obtained by replacing HT-6 in the synthesis of HT-6 by replacing the compound (2) with a compound represented by the following formula (14) and further replacing the compound (4) with benzaldehyde. Was synthesized in the same manner as above.
In the triphenylamine derivative HT-3, R _{1 to} R ₁₂ of the triphenylamine derivative represented by the general formula (1) are hydrogen atoms, and two of the double-bonded groups are bonded to a nitrogen atom. N1 and n2 are both compounds bonded to the phenyl group at the para position with respect to the nitrogen atom. The ¹ H-NMR spectrum of the triphenylamine derivative HT-3 is shown in FIG.

(Synthesis of HT-4)
In the synthesis of HT-6, HT-4 in the present invention is obtained by replacing the compound (2) described above with the compound represented by the above formula (14), the compound (4) with benzaldehyde, and the compound (11) with the following: The compound was synthesized in the same manner as HT-6 by replacing with the compound represented by formula (15).
In the triphenylamine derivative HT-4, R _{1 to} R ₁₂ of the triphenylamine derivative represented by the general formula (1) are hydrogen atoms, and one of the double-bonded groups is phenyl bonded to a nitrogen atom. It is a compound in which n1 and n2 are both 1 bonded to the group at the meta position relative to the nitrogen atom.

(Synthesis of HT-5)
HT-5 in the present invention was synthesized in the same manner as HT-6 by replacing the compound (4) with benzaldehyde in the synthesis of HT-6.
In the triphenylamine derivative HT-5, R _{1 to} R ₁₁ of the triphenylamine derivative represented by the general formula (1) are hydrogen atoms, and two of the double-bonded groups are bonded to a nitrogen atom. N1 is 1 and n2 is 0, which is bonded to the phenyl group at the para position with respect to the nitrogen atom.

融点は、融点測定装置（Ｙａｎａｃｏ製：ＭＰ）を用いて測定した。 (Measurement of solubility and melting point)
The solubility and melting point of the hole transport agent were measured by the following methods.
The solubility according to the present invention is the saturation concentration of the sample with respect to the solution, and when a small amount of THF (tetrahydrofuran) is added to 100 mg of the sample of the hole transport agent and this is repeatedly shaken / leaved, the solution reaches saturation. From the amount of THF added (Wmg), the following formula was used.

The melting point was measured using a melting point measuring apparatus (manufactured by Yanaco: MP).

[Examples 1 to 18 and Comparative Examples 1 to 11]
[Manufacture of electrophotographic photosensitive member]
(Hole transport agent)
As a hole transport agent, HT-1 to -6 of the present invention and HT-7 and 8 and HT-9 to 13 shown below were used as comparative examples. The solubility and melting point of HT-2, 3, 6-13 are as shown in Table 1. The measurement was performed by the same method as the above measurement method.

(Electron transfer agent)
As the electron transporting agent, the following two types of electron transporting agents (ET-1, 2) were used.

Example 1
5 parts by weight of X-type metal-free phthalocyanine as a charge generating agent, 80 parts by weight of HT-1 as a hole transporting agent, 50 parts by weight of ET-1 as an electron transporting agent, and 100 parts by weight of polycarbonate as a binder resin Were mixed and dispersed in a ball mill for 50 hours together with 800 parts by weight of tetrahydrofuran as a solvent to prepare a coating solution for a single-layer type photosensitive layer. Next, this coating solution was applied on a conductive substrate made of an aluminum base tube by dip coating and dried with hot air at 100 ° C. for 30 minutes to produce a single-layer type photoreceptor having a film thickness of 25 μm.
(Examples 2-18, Comparative Examples 1-11)
In the single-layer photosensitive layer coating solution produced in Example 1, HT-1 to 13 as the hole transport agent and ET-1 and 2 as the electron transport agent were used instead of the combinations shown in Table 2, A single layer type photoreceptor was produced in the same manner as in Example 1.

(Evaluation test and evaluation method)
Any of the electrophotographic photoreceptors produced in Examples 1 to 18 and Comparative Examples 1 to 11 was installed in a GENTEC drum sensitivity tester, and an electrical property test and the presence or absence of crystallization on the drum surface were evaluated. It was. In the electrical characteristic test, first, charging was performed so that the initial surface potential V ₀ was + 700V. Next, monochromatic light (light intensity 1.5 μJ / cm ² ) having a wavelength of 780 nm (half-width 20 nm) extracted from the white light of the halogen lamp using a bandpass filter is irradiated on the surface of the photosensitive member for 1.5 seconds to be exposed. The surface potential at the time when 0.5 seconds elapsed from the start was measured, and this was defined as the residual potential V _L (V). The residual potential V _L (V) is 130 V or less. The presence or absence of crystallization on the drum surface was confirmed by visual observation at the final repetition point. These results are shown in Table 2.
Regarding the crystallization on the drum surface, the case where crystallization was not observed was indicated by ◯, the case where slight crystallization was observed was indicated by Δ, and the case where crystallization was observed was indicated by ×.

The results are shown in Table 2.

As is clear from Table 1, in the electrophotographic photoreceptors of Comparative Examples 1 to 3, 7, 9, and 10 using HT-7, 9, 11, and 12, since crystals were precipitated in the photosensitive layer, they were practically used. Could not be used. Further, in the electrophotographic photoreceptors of Comparative Examples 4 to 6, 8, and 11 using HT-8, 10, and 13, the residual potential _VL was high and sufficient sensitivity was not obtained.

On the other hand, in the electrophotographic photoreceptors of Examples 1 to 18 using HT-1 to -6 of the present invention, the residual potential V _L is low, and high sensitivity is obtained by preventing crystal precipitation in the photosensitive layer. An electrophotographic photosensitive member can be obtained.

It is a graph which shows the < ¹ > H-NMR spectrum of the triphenylamine derivative HT-2 obtained by the synthesis | combination of HT-2. It is a graph which shows the < ¹ > H-NMR spectrum of the triphenylamine derivative HT-3 obtained by the synthesis | combination of HT-3. It is a graph which shows the < ¹ > H-NMR spectrum of the triphenylamine derivative HT-6 obtained by the synthesis | combination of HT-6.

Claims (2)

A triphenylamine derivative represented by the following general formula (1).

(In the formula, R _a represents a phenyl group, and R ₁ to R ₁₂ are the same or different groups, and are a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a phenoxy group. , An aralkyl group having 6 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms, wherein the alkyl group, aralkyl group, or aryl group may have a substituent, and n1 and n2 are 0 or 1 Indicates an integer.)   An electrophotographic photoreceptor comprising a photosensitive layer containing at least a charge generating agent and a charge transport agent, wherein the charge transport agent comprises a triphenylamine derivative represented by the general formula (1) according to claim 1. An electrophotographic photosensitive member characterized by the above.

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