JP3259454B2 - Triarylamine compound and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel triarylamine compound and a method for producing the same. More specifically, the present invention relates to a triarylamine compound useful as a charge transport material in an electrophotographic photoreceptor and a method for producing the same.

[0002]

2. Description of the Related Art The use of triarylamine compounds as photoconductive materials for electrophotographic photoreceptors is well known. For example, U.S. Pat. No. 3,180,730 describes triphenylamine and its substitutions, and U.S. Pat. No. 3,706,554 describes tri-p-.
It has been proposed to use tolylamine compounds as photoconductive materials. JP-A-57-195254 discloses the use of various triarylamine compounds in the charge transport layer of a laminated electrophotographic photoreceptor. JP-A-61-132954 discloses a trisazo pigment. And an electrophotographic photoreceptor using a triarylamine compound. U.S. Pat. No. 4,946,754 proposes an electrophotographic photoreceptor using a diarylbiphenylamine and various charge generating materials. Also,
In recent years, triarylamine compounds having various substituents have been proposed, for example, JP-A-1-280763,
JP-A-2-36156, JP-A-3-282478, JP-A-3-78755, JP-A-3-78756, JP-A-3-78
78757, JP-A-2-230255, JP-A-2-19
0862, JP-A-2-190863, JP-A-2-178
670, JP-A-2-178668, JP-A-2-17886
67, JP-A-2-178666, JP-A-2-15624
7, JP-A-2-134642, JP-A-4-19385
2, JP-A-4-133064, JP-A-4-111865
8, JP-A-3-285960, JP-A-3-24975
9, JP-A-3-223664, JP-A-3-11405
8, JP-A-3-127965, JP-A-3-10173
9, JP-A-3-102361, JP-A-3-58054,
JP-A-3-56967, JP-A-3-7946, JP-A-3-3
-7248, JP-A-3-5443, JP-A-3-217
4, JP-A-2-243657, JP-A-2-17866
9, JP-A-3-213866, JP-A-3-163458
These are disclosed in the respective publications.

[0003]

The most representative triarylamine compounds are triphenylamine and tri-p-tolylamine, which are
Although effective as a photoconductive material for electrophotographic photoreceptors, it has a low molecular weight and a low melting point, so when electrophotographic photoreceptors using it as a charge transport layer are repeatedly used, migration occurs in the charge transport layer. And bleeds easily, causing a change with time. In order to improve the disadvantage of the migration of the triarylamine compound in the charge transport layer and the aging of the electrophotographic photosensitive member due to bleeding, as a general method, it is conceivable to increase the molecular weight by introducing a substituent. When a substituent that is not effective in charge transfer is introduced, the intermolecular distance is simply increased and the charge mobility is reduced.
The present inventors have already reported in the Journal of the Society of Electrophotography, 30 , 16
As described in (1990), it has been reported that an alkyl group is a substituent effective for charge transfer. However, when an alkyl group having a long chain of ethyl group or more is introduced, steric hindrance of the alkyl group is caused. Stacking is difficult, the melting point is rather lowered, migration is more likely to occur, and it is difficult to obtain a stable electrophotographic photosensitive member. Accordingly, an object of the present invention is to provide a novel triarylamine compound which does not have the above-mentioned disadvantages when used as a photoconductive material in an electrophotographic photosensitive member. Another object of the present invention is to provide a method for inexpensively producing a novel triarylamine compound.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the simultaneous introduction of two methyl groups into a phenyl group lowers the melting point as in the case of introducing a long-chain alkyl group. Migration can be effectively prevented, and when the introduction position is at the 3,4-position of the phenyl group, high charge mobility can be obtained in the charge transport layer of the electrophotographic photosensitive member. ,Also,
The inventors have found that the present invention has excellent repetition stability, and have completed the present invention.

[0005] The novel triarylamine compound of the present invention is represented by the following general formula (I).

Embedded image ( Wherein , Ar ₁ and Ar ₂ each represent a phenyl group
Other represents a condensed ring group, said phenyl group is an alkyl, phenyl, alkoxy, or alkyl-substituted phenyl group rather it may also be substituted with, fused ring group may be substituted with an alkyl group
Good. Provided that _one of Ar ₁ and Ar ₂ is substituted or
An unsubstituted fluorenyl group, the other being a phenyl group or
Represents an alkyl-substituted phenyl group, and Ar ₁ and A
when r ₂ simultaneously represents a p-methylphenyl group, and
Ar ₁ and Ar ₂ simultaneously form a phenyl-substituted phenyl group
Represented or substituted with an alkyl-substituted phenyl group.
Excluding the case of representing a phenyl group. )

The triarylamine compound represented by the above general formula (I) of the present invention is a novel substance and uses a copper catalyst of an amine and an aryl halide compound which is a generally well-known method. It can be synthesized by a conventional condensation reaction.

That is, after acetylation of 3,4-xylysine, a halogenated aryl represented by the general formula Ar ₁ -X (where X represents a halogen atom and Ar ₁ has the same meaning as described above). N-
(3,4-dimethylphenyl) -N-arylamine is represented by the general formula Ar ₂ -X (wherein X represents a halogen atom,
r ₂ has the same meaning as described above. Can be synthesized by condensation with the aryl halide compound represented by the formula (1). Examples of the halogen in the halogenated aryl compound include bromine and iodine. Generally, iodine is preferred because of its high reactivity, but bromine is preferred in terms of cost. In this case, when 4-bromo-o-xylene is used as the aryl halide compound, 4-bromo-o-xylene and 3-bromo-xylene are used.
It can be used as a mixture with o-xylene. The preferred production method of the present invention is based on the general formula Ar ₁ —NH ₂ (A
r ₁ has the same meaning as described above), and after acetylation, a condensation reaction is carried out using a mixture of 3-bromo-o-xylene and 4-bromo-o-xylene to produce the following compound General formula (II)

Embedded image (Wherein, Ar ₁ has the same meaning as defined above), and a diarylamine compound represented by the general formula Ar ₂ -X
₁ (wherein X ₁ represents a bromine atom or an iodine atom;
r ₂ has the same meaning as described above. )). In the condensation reaction after the above acetylation, 4-bromo-o-xylene may be used to introduce a 3,4-xylyl group.
Since 4-bromo-o-xylene is difficult to purify, the present invention is characterized by using a mixture of 4-bromo-o-xylene and 3-bromo-o-xylene which is easily available. In that case, 3-bromo-o-xylene has a large steric hindrance due to the presence of a methyl group adjacent to Br, and significantly decreases reactivity with 4-bromo-o-xylene. 3,4-xylyl substituent is mainly produced. Further, even when a mixture is produced, the 3,4-xylyl-substituted product can be easily separated and purified by utilizing the difference in solubility.

The copper catalyst used in the condensation reaction includes copper metal powder, copper sulfate, cuprous oxide, copper iodide, copper sulfate and the like. The amount of the copper catalyst used can be arbitrarily set according to the reaction rate. However, if the amount used is large, stirring, separation, etc. become difficult. Is used in an amount of 1 mol or less. In addition, hydrogen halide generated during the condensation reaction is neutralized by adding a base such as sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide. The amount of the base to be used can be arbitrarily set at an amount equal to or more than the amount of hydrogen halide to be generated, but if it is large, stirring and separation become difficult, so that the amount is 10 equivalents or less, preferably 5 equivalents or less. Used. It is also effective to add a high-boiling hydrocarbon compound such as tridecane or nitrobenzene in order to effectively remove generated water from the reaction system during the reaction.

Ar ₁ and A in the general formula (I)
If r ₂ represents a phenyl group, a phenyl group, an alkyl, phenyl, optionally substituted by alkoxy or alkyl-substituted phenyl group. A plurality of these substituents may be present in the phenyl group. Specific examples where Ar ₁ and Ar ₂ each represent a condensed ring group include, for example, a naphthyl group, an anthracenyl group, a pyrenyl group, a fluorenyl group and the like. These groups may be further substituted with an alkyl group.

Specific examples of the triarylamine compound of the present invention represented by the general formula (I) include those in which Ar ₁ and Ar ₂ are shown in Tables 1 to 4 below. In the table, Me, Et, Pr and Bu are shown.
Represents a methyl group, an ethyl group, a propyl group, and a butyl group, respectively.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

The triarylamine compound represented by the above formula (I) of the present invention can be used as a charge transport material in an electrophotographic photosensitive member. For example, in an electrophotographic photoreceptor having a charge generation layer and a charge transport layer formed on a conductive support such as aluminum, the above-mentioned triarylamine compound of the present invention is contained in the charge transport layer. More specifically, it may be formed by applying a coating solution containing the triarylamine compound represented by the general formula (I) of the present invention and a binder resin. As the binder resin, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-vinyl acetate-maleic anhydride Acid copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-
Known resins such as N-vinylcarbazole and polysilane can be used.

Among these binder resins, the following structural formula (II)
When the polycarbonate resins represented by I) to (VII) or the polycarbonate resins obtained by copolymerizing them are used, a uniform film having good compatibility is obtained, and the electrophotographic photosensitive member is Shows particularly good properties.

Embedded image These binder resins can be used alone or in combination of two or more. The mixing ratio (weight ratio) of the charge transport material and the binder resin is preferably from 10: 1 to 1: 5.

[0017]

The present invention will be described below by way of examples. Example 1 (1) [Synthesis of 3,4-dimethylacetanilide] 240 ml of concentrated hydrochloric acid was added to 6.6 liters of distilled water, and 330 g of 3,4-xylysine was dissolved therein. Then
278 g of acetic anhydride was added, and 721 g of sodium acetate trihydrate was further dissolved in 1200 ml of distilled water and added dropwise.
After stirring at room temperature for 3 hours, 6 kg of ice was added, and the precipitated crystals were washed well with water and recrystallized with a mixed solvent of acetone-hexane to give 3,4-dimethylacetylacetanilide 36
2 g were obtained. (Melting point 102-104 ° C, colorless crystals)

(2) [Synthesis of 3,4,4'-trimethyldiphenylamine] 120 g of 3,4-dimethylacetanilide, 193 g of p-iodotoluene, 122 g of anhydrous potassium carbonate and 2 g of copper sulfate pentahydrate were added to 2 liters of 3 liters. The mixture was placed in a one-necked flask, reacted at 200 ° C. for 30 hours under a nitrogen stream, and then cooled to room temperature. 120 g of potassium hydroxide was added to the reaction mixture.
Was dissolved in 600 ml of ethanol, and 1.5
Heated to reflux for an hour. After the completion of the reaction, the mixture was cooled to room temperature, and then the inorganic salt was separated by filtration. The solvent was distilled off from the filtrate under reduced pressure. This was distilled under reduced pressure (〜145 ° C./0.2 mmHg) and recrystallized from methanol to obtain 121 g of 3,4,4′-trimethyldiphenylamine. (Melting point 62-64 ° C, colorless crystals)

[0019]

(3) [N- (4-methylphenyl) -N- (3,4-
Dimethylphenyl) biphenyl-4-amine (CT-
Synthesis of 3 )] 20.7 g of 3,4,4'-trimethyldiphenylamine synthesized in the above (2), 25 g of 4-iodobiphenyl, 13 g of anhydrous potassium carbonate, 2 g of copper sulfate pentahydrate
And 20 ml of n-tridecane was put into a 500 ml three-necked flask, reacted at 200 ° C. for 30 hours under a nitrogen stream, and then cooled to room temperature. The reaction mixture was purified by column on activated alumina (solvent: n-hexane / toluene = 10 /
1) and the solvent was distilled off under reduced pressure. The residue was recrystallized from a mixed solvent of ethyl acetate / ethanol to obtain 28 g of N- (4-methylphenyl) -N- (3,4-dimethylphenyl) biphenyl-4-amine. (Melting point 128-129.5
C, colorless crystals, IR are shown in FIG . )

Example 2 (1) [Synthesis of 3,3 ', 4,4'-tetramethyldiphenylamine] 120 g of 3,4-dimethylacetanilide synthesized in Example 1 (1), 4-bromo-o- 253 g of xylene (containing about 70%, containing about 30% of 3-bromo-o-xylene), 122 g of anhydrous potassium carbonate and 2 g of copper sulfate pentahydrate were placed in a two-liter three-necked flask and placed under a stream of nitrogen. After reacting at 200 ° C. for 60 hours, it was cooled to room temperature. A solution of 120 g of potassium hydroxide dissolved in 600 ml of ethanol was added to the reaction mixture, and the mixture was heated under reflux for 4 hours. After the completion of the reaction, the mixture was cooled to room temperature, and then the inorganic salt was separated by filtration. The solvent was distilled off from the filtrate under reduced pressure. This was distilled under reduced pressure (〜155 ° C./0.2 mmHg) and recrystallized from methanol to obtain 117 g of 3,3 ′, 4,4′-tetramethyldiphenylamine. (Melting point: 80-82 ° C, colorless crystals)

(2) [Synthesis of 3,3 ′, 4,4 ′, 4 ″ -pentamethyltriphenylamine (CT- 12 )] 3,3 ′, 4,4′-tetramethyldiphenylamine 5
0 g, p-iodotoluene 58 g, anhydrous potassium carbonate 3
0 g, copper sulfate pentahydrate 2 g and n-tridecane 10 m
l into a 1-liter three-necked flask, and under a nitrogen stream,
After reacting at 200 ° C. for 40 hours, it was cooled to room temperature. The reaction mixture was purified by column with activated alumina (solvent: n-hexane / toluene = 10/1), and the solvent was distilled off under reduced pressure. The residue was recrystallized from a mixed solvent of ethyl acetate / ethanol to obtain 58 g of 3,3 ', 4,4', 4 "-pentamethyltriphenylamine (melting point: 115 to 117.5).
° C., indicating colorless crystals, the IR in Figure 2. )

Example 3 [Synthesis of N, N-bis (3,4-dimethylphenyl) biphenyl-4-amine (CT- 13 )] Example 2 , 3,3 ', 4 synthesized in (1) 4 '
31 g of tetramethyldiphenylamine, 40 g of 4-iodobiphenyl, 19 g of anhydrous potassium carbonate, 2 g of copper sulfate pentahydrate and 20 ml of n-tridecane were placed in a 500 ml three-necked flask and reacted at 200 ° C. for 28 hours under a nitrogen stream. Then, it was cooled to room temperature. The reaction mixture was purified by column with activated alumina (solvent: n-hexane / toluene = 10/1), and the solvent was distilled off under reduced pressure. The residue was recrystallized with a mixed solvent of ethyl acetate / ethanol to obtain 37 g of N, N-bis (3,4-dimethylphenyl) biphenyl-4-amine. (Melting point: 119-120.5 ° C., colorless crystal, IR is shown in FIG. 3 )

[0024] Example 4 [N, N-bis (3,4-dimethylphenyl) naphthalene-1-amine (CT- 17) Synthesis] Example 2 (1) 3,3 synthesized in ', 4, 4 '
7.2 g of tetramethyldiphenylamine, 12.2 g of 1-iodonaphthalene, 5 g of anhydrous potassium carbonate, 0.5 g of copper sulfate pentahydrate and 10 ml of n-tridecane
Put into a 0 ml three-necked flask, and place under nitrogen stream at 200 ° C.
And then cooled to room temperature. The reaction mixture is purified by column on activated alumina (solvent: n-hexane)
Then, the solvent was distilled off under reduced pressure. The residue was recrystallized from ethanol to obtain 4.2 g of N, N-bis (3,4-dimethylphenyl) naphthalen-1-amine. (Melting point 125-12
7 ° C., pale yellow crystals, the IR shown in Figure 4. )

Example 5 [Synthesis of 3,3 ', 3 ", 4,4', 4" -hexamethyltriphenylamine (CT- 23 )] 3,3 ', 4,4'-tetramethyldiphenylamine 5
0 g, 4-bromo-o-xylene (purity about 70%, about 3
70 g, 0 g of 3-bromo-o-xylene, manufactured by Aldrich), 30 g of anhydrous potassium carbonate, 2 g of copper sulfate pentahydrate, 1 g of iodine and 10 ml of n-tridecane
Liter in a three-necked flask and placed under a stream of nitrogen.
After reacting at 150 ° C. for 150 hours, it was cooled to room temperature. From the reaction mixture, unreacted bromoxylene was distilled under reduced pressure. The residue was purified by column with activated alumina (solvent: n-hexane / toluene = 10/1), and the solvent was distilled off under reduced pressure. The residue is
Approximately 7 to 1 of 3,3 ', 3 ", 4,4', 4" -hexamethyltriphenylamine and 2,3,3 ', 3 ", 4', 4" -hexamethyltriphenylamine It was a mixture. This was recrystallized with a mixed solvent of ethyl acetate / ethanol to obtain 30 g of 3,3 ', 3 ", 4,4', 4" -hexamethyltriphenylamine. (Melting point 137-1
39 ° C., colorless crystals, the IR shown in Figure 5. )

Examples 6 to 13 In the same manner as in Example 1, the compounds shown in Table 5 were synthesized.

[Table 5]

Test Example The mobility of a film obtained by mixing the compounds shown in Table 6 below with a polycarbonate resin at a weight ratio of 1: 1 was measured by the method described in Journal of the Electrographic Society of Japan, 30, 16 (1990). . The mobility at an electric field strength of 30 V / μm is shown in Table 6 below.

[0028]

[Table 6] Note) Comparative compound 1: 4,4 ', 4 "-trimethyltriphenylamine Comparative compound 2: 2,4,4', 4" -tetramethyltriphenylamine Comparative compound 3: N, N-diphenylbiphenyl-4-
Amine

Application Example 1 10 parts of a zirconium compound (trade name: Organix ZC540, manufactured by Matsumoto Pharmaceutical Co., Ltd.) and 1 part of a silane compound (trade name: A1110, manufactured by Nippon Unicar Co., Ltd.) and 40 parts of i-propanol were placed on an aluminum substrate. A solution consisting of 20 parts of butanol is applied by a dip coating method.
Heating was performed at 50 ° C. for 10 minutes to form a 0.5 μm-thick undercoat layer. x-type metal-free phthalocyanine 1
Parts were 1 part of polyvinyl butyral resin (trade name: Esrec BM-S, manufactured by Sekisui Chemical Co., Ltd.)
The resulting coating solution was applied to the undercoat layer by dip coating, and dried by heating at 100 ° C. for 10 minutes to form a charge generation layer. Next, 2 parts of the above exemplified compound CT-3 and 3 parts of a polycarbonate resin represented by the following formula were dissolved in 20 parts of monochlorobenzene,
The obtained coating solution was applied on the charge generation layer by a dip coating method, and dried by heating at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm.

Embedded image (In the formula, n represents an integer indicating the degree of polymerization.)

The electrophotographic characteristics of the electrophotographic photoreceptor obtained as described above were measured at room temperature and normal humidity (20 ° C.) using an electrostatic copying paper test apparatus (Electrostatic Analyzer EPA-8100, manufactured by Kawaguchi Electric Co., Ltd.). , 40% RH), charged by performing a corona discharge of -6 kV, and then applying light to a tungsten lamp using a monochromator for 80 hours.
It was converted to monochromatic light of 0 nm, adjusted to 1 μW / cm ² on the surface of the photoreceptor, and irradiated. And its surface potential V0
(Volts) and half-exposure E1 / 2 (erg / cm ² ) were measured, and then 10 lux of white light was irradiated for 1 second to measure residual potential VRP (volts). Further, V0, E1 / 2, and VRP after the above-described charging and exposure were repeated 1000 times were measured, and the variations were represented by ΔV0, ΔE1 / 2, and ΔVRP. The results are shown in Table 7.

APPLICATION EXAMPLES 2 TO 13 An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Application Example 1, except that the exemplified compound CT-3 was changed to the compounds shown in Table 7. Table 7 shows the results. Comparative Application Examples 1 to 3 Exemplified Compound CT- which is a charge transport material in Application Example 1
In place of 3, 4,4 ', 4 "-trimethyltriphenylamine, 4-ethyl-4', 4" -dimethyltriphenylamine and N, N-diphenyl-biphenyl-4
A photoconductor was prepared in the same manner as in Application Example 1 except that an amine was used, and the same measurement was performed. Table 7 shows the results.

[0032]

[Table 7]

[0033]

The triarylamine compound of the present invention is a novel compound and is useful as a charge transport material in an electrophotographic photosensitive member. The electrophotographic photoreceptor of the present invention produced using this triarylamine compound has high sensitivity, excellent repetition stability and environmental stability.

[Brief description of the drawings]

FIG. 1 shows the triphenylamine compound I of Example 1.
It is an R absorption spectrum figure.

FIG. 2 shows I of the triphenylamine compound of Example 2.
It is an R absorption spectrum figure.

FIG. 3 shows a triphenylamine compound I of Example 3.
It is an R absorption spectrum figure.

FIG. 4 shows I of the triphenylamine compound of Example 4.
It is an R absorption spectrum figure.

FIG. 5 shows the triphenylamine compound I of Example 5
It is an R absorption spectrum figure.

FIG. 6 shows the triphenylamine compound I of Example 6.
It is an R absorption spectrum figure.

FIG. 7 shows I of the triphenylamine compound of Example 7.
It is an R absorption spectrum figure.

FIG. 8 shows I of the triphenylamine compound of Example 8.
It is an R absorption spectrum figure.

FIG. 9 shows I of the triphenylamine compound of Example 9.
It is an R absorption spectrum figure.

FIG. 10 is an IR absorption spectrum of the triphenylamine compound of Example 10.

FIG. 11 is an IR absorption spectrum of the triphenylamine compound of Example 11.

FIG. 12 is an IR absorption spectrum of the triphenylamine compound of Example 12.

FIG. 13 is an IR absorption spectrum of the triphenylamine compound of Example 13.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-181950 (JP, A) JP-A-3-127765 (JP, A) JP-A-6-250421 (JP, A) JP-A-6-250421 11868 (JP, A) JP-A-6-107605 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 211/54-211/61 C07C 209/10 C07C 217/92 G03G 5/06 312 CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] 1. A triarylamine compound represented by the following general formula (I). Embedded image (Wherein, Ar ₁ and Ar ₂ each represent an unsubstituted fused ring
Group, represents an alkyl-substituted fused ring group, or a phenyl group ,
It said phenyl group is an alkyl, phenyl, may be alkoxy or substitution with an alkyl-substituted phenyl group. However, when _one of Ar ₁ and Ar ₂ is a substituted or unsubstituted fluorenyl group and the other represents a phenyl group or an alkyl-substituted phenyl group, a case where Ar ₁ and Ar ₂ simultaneously represent a p-methylphenyl group, and Except when Ar ₁ and Ar ₂ simultaneously represent a phenyl-substituted phenyl group or a phenyl group substituted with an alkyl-substituted phenyl group. ) 2. The triarylamine compound according to claim 1, wherein Ar ₁ is a 3,4-dimethylphenyl group. 3. The triarylamine compound according to claim 1, wherein Ar ₁ and Ar ₂ are both 3,4-dimethylphenyl groups. 4. After acetylating an amino compound represented by the general formula: Ar ₁ -NH ₂ (Ar ₁ has the same meaning as described above), 3-bromo-o-xylene and 4-bromo-o- A condensation reaction is carried out using a mixture of xylene to form the following general formula (II): (Wherein, Ar ₁ has the same meaning as defined above), and a diarylamine compound represented by the general formula: Ar ₂ −
X ₁ (wherein, X ₁ represents a bromine atom or an iodine atom,
Ar ₂ has the same meaning as described above. 3. The method for producing a triarylamine compound according to claim 1, wherein the condensation is carried out with the aryl halide compound represented by the formula (1).