KR20070048930A - Organic photosensitive conductor improved resistance to crack and the method for producing the same - Google Patents

Abstract

An electrophotographic photosensitive member and a method of manufacturing the same are disclosed. The electrophotographic photosensitive member may include a conductive support; A charge generating layer coated on the conductive support; And a charge transport layer stacked on the charge generating layer. The charge transport layer is composed of at least a charge transport material, a binder resin, and a solvent, and the charge transport material is preferably a tetraphenylbutadiene derivative. The manufacturing method is coated with a charge generating layer coating liquid on the surface of the photoconductor support and then dried, and a charge transport layer coating liquid is coated on the surface of the support. Thereafter, the coated support is first dried at low temperature, and then the first dried support is secondarily dried at high temperature. The photoconductor thus manufactured has excellent electrophotographic characteristics, and image noise is prevented and no crack occurs even with time.

Photosensitive member, charge generating layer, charge transport layer, drying, crack

Description

Organic Photosensitive Conductor Improved Resistance to Crack and the Method for Producing the Same}

1 is a schematic configuration diagram of a drying apparatus in the manufacturing process of the photosensitive member according to the present invention.

<Description of the symbols for the main parts of the drawings>

1: photosensitive member 2: pallet

3, 6: Constant temperature chamber 4, 7: Cooling fan

The present invention relates to the manufacture of an electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member having excellent electrophotographic characteristics, and preventing image noise and no cracking over time, and a method of manufacturing the same. will be.

As is well known, electrophotographic photosensitive members are widely used in the field of electrophotographic facsimile machines, copiers, laser printers, CRT printers, LED printers, liquid crystal printers or laser electrophotography. Such an electrophotographic photosensitive member generally includes a conductive support, a charge generation layer (hereinafter referred to as "CGL") coated on the conductive support, and a charge transfer layer stacked on the charge generation layer; Hereinafter referred to as "CTL").

In the conventional photoreceptor, a tetra phenyl butadiene derivative is mainly used as a charge transport material for forming the charge transport layer. However, tetra phenyl butadiene has excellent electrostatic properties such as electrophotographic properties and light resistance, but has a large intermolecular interaction and is difficult to apply to various binder resins. For example, when the mixing ratio of the charge transport material to the binder resin is made very large, the electrostatic properties of the photosensitive member are impaired. In addition, when the mixing ratio is made small, cracks are often generated in the charge transport layer, resulting in image defects. Since such cracks gradually occur over time after production, cracks may occur after being shipped to the market, causing problems in the reliability of products.

The present invention has been proposed to solve the above problems of the prior art, the object of which is to improve the drying conditions for the charge transport layer (CTL) by removing the internal stress of the charge transport layer, to provide an electrophotographic photosensitive member that minimizes crack failure Is in.

Another object of the present invention is to provide a method of manufacturing such an electrophotographic photosensitive member.

Electrophotographic photosensitive member of the present invention for achieving the above object is a conductive support; A charge generating layer coated on the conductive member; And a charge transport layer stacked on the charge generating layer. It includes, the charge transport layer is composed of at least a charge transport material, a binder resin and a solvent, the charge transport material is characterized in that composed of tetraphenylbutadiene derivatives such as formula (1).

In Formula 1, R1, R2, R3, and R4 each independently represent an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 20 carbon atoms.

In addition, the method for manufacturing an electrophotographic photosensitive member according to the present invention comprises the steps of applying a coating liquid containing a charge generating material to the surface of the support and drying to form a charge generating layer; And applying a coating liquid containing a charge transport material on the surface of the support on which the charge generating layer is formed, and then drying the charge liquid to form a charge transport layer. The drying of the charge transport layer may include: After drying, it is characterized in that the secondary drying at a high temperature.

Drying of the said charge generation layer, Preferably, it carries out in 100-130 degreeC.

Preferably, the charge transport layer is dried in the range of 70 to 90 ° C., followed by secondary drying in the range of 110 to 130 ° C. The primary drying is preferably carried out longer than the secondary drying. For example, the first drying may be performed for about 50 ± 10 minutes, and the second drying may be performed for 10 minutes ± 5 minutes.

Hereinafter, the electrophotographic photosensitive member according to the present invention will be described in detail.

An electrophotographic photosensitive member according to the present invention includes a conductive support, a charge generating layer applied on the conductive support, and a charge transport layer laminated on the charge generating layer.

The support may be one obtained by conducting a conductive treatment on a metal such as aluminum, an aluminum alloy, nickel, stainless, glass or a resin film. The support may be used in various shapes such as plate shape, cylindrical shape, and film shape.

It is preferable to form an insulating layer or the like on the surface of these supports so as to have a uniform and good adhesion. Such an insulating layer may be provided on the metal surface as an oxide film layer or as a resin film layer. As the material of the resin coating layer, insulating polymers such as casein, polyvinyl alcohol, polyamide, polyimide, melamine, cellulose, or conductive polymers such as polythiophene, polypyrrole and polyaniline, or metal oxide powders are added to these polymers. May be used.

The charge generating layer is composed of a charge generating material, a binder resin, a solvent and an additive.

The charge generating material may be used alone or in combination of two or more thereof. The charge generating materials include metal phthalocyanine (Phthalocyanine) and its derivatives alone or in combination, copper phthalocyanine (Aluminum chloride Phthalocyanine), titanium chloride phthalocyanine (Titanyl Phthalocyanine) and metal substituted in the center of phthalocyanine ), Vanadium oxide Phthalocyanine, Indium chloride Phthalocyanine, Hydroxy gallium Phthalocyanine, Tin oxide Phthalocyanine, Tin oxide Phthalocyanine, etc. Derivatives may be used alone or in combination of two or more thereof. It is also possible to use a combination of a metal-free phthalocyanine or a derivative thereof and a metal-substituted phthalocyanine or a derivative thereof, a metal-free phthalocyanine and a metal-based phthalocyanine.

The binder resin may be vinyl acetate, vinylpyrrolidine, acrylic, polyurethane, polycarbonate, polyester, polyamide, epoxy, polyvinyl butyral, polyvinyl acetal, phenoxy resin, silicone resin, vinyl chloride resin, vinyl chloride It may be used in the form of a lidene resin, a formal resin, a cellulose resin or a copolymer thereof, or a halide or cyanoethyl compound thereof may be used alone or in combination as appropriate.

In the case of the charge generating layer, the content ratio of the charge generating material and the binder resin may range from 5: 1 to 1: 3. Outside the range of the content ratio, the stability of the solution is lowered, the coating quality of the charge generating layer is lowered or the sensitivity is deteriorated, and the electrical potential is deteriorated such as the exposure potential is increased. A more preferable content ratio of the charge generating material and the binder resin is 2: 1 to 1: 1.

The solvent is methyl isopropyl ketone, methyl isobutyl ketone, 4-methoxy-4-methyl-2-pentanone, isopropyl acetate, isobutyl acetate, tertiary butyl acetate, isopropyl alcohol, isobutyl alcohol, acetone, Methylethylketone, cyclohexanone, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane , Dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, 1-methoxy-2-propanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, methyl cellosolve, Butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine, triethylenediamine, N, N'-dimethylformamide, benzene, toluene, xylene, methylbenzene, ethylbenzene, cyclohexane, etc. It can be used in combination.

The additive may be used alone or as a suitable combination of a dispersant, a light stabilizer, an antifoaming agent, a surfactant.

The charge transport layer is composed of a charge transport material, a binder resin, a solvent and an additive.

The charge transport material that can be used as the charge transport layer may be any material that can play a role in transferring charges generated in the charge generating layer to the drum surface. For example, 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene, N, N'-bis (olso, para-dimethylphenyl) -N, N'- Diphenylbenzidine, 3,3'-dimethyl-N, N, N'N'-tetrakis-4-methylphenyl- (1,1'-biphenyl) -4,4'-diamine, N-ethyl-3- Carbozolylaldehyde-N, N'-diphenylhydrazone, 4- (N, N-bis (para-toluyl) amino) -betaphenylstilbene, N, N, N ', N'-tetrakis (3 -Methylphenyl) -1,3-diaminobenzene, N, N-diethylaminobenzaldehydediphenyl-hydrazone, N, N-dimethylaminobenzaldehydediphenyl-hydrazone, 4-dibenzylamino-2-methylbenzaldehydedi Phenylhydrazone, 2,5-bis (4-aminophenyl)-[1,3,4] oxadiazole, (2-phenylbenzo [5,6-b] -4H-thiopyran-4ylidene)- Propanedinitrile-1,1-dioxide, 4-bromo-triphenylamine, 4,4 '-(1,2-ethanediylidene) -bis (2,6-dimethyl-2,5-cyclohexadiene -1-one), 3,4,5-triphenyl-1,2,4-triazole, 2- (4-methylphenyl) -6-phenyl-4H-thiopyran-4-yl Lidene] -propanedinitrile-1,1-dioxide, 4-dimethylamino-benzaldehyde-N, N-diphenylhydrazone, 9-ethylcarbazole-3-aldehyde-N-methyl-N-phenylhydrazone, 5 -(2-chlorophenyl) 3- [2- (2-chlorophenyl) ethenyl "-1-phenyl-4,5-dihydro-1H-pyrazole, 4-diethylamino-benzaldehyde-N, N- Diphenylhydrazone, N-biphenylyl-N-phenyl-N- (3-methylphenyl) amine, 9-ethylcarbazole-3-aldehyde-N, N-diphenylhydrazone, 3,5-bis (4 -tert-butylphenyl) 4-phenyltriazole, 3- (4-biphenylyl) -4-phenyl-5-tert-butylphenyl-1,2,4-triazole, 4-diphenylamino-benzaldehyde- N, N-diphenylhydrazone, 5, (4-diethylaminophenyl) -3- [2- (4-diethylaminophenyl) -ethenyl] -1-phenyl-4,5-dihydro-1 -Pyrazole, N, N'-di (4-methylphenyl) -N, N'-diphenyl-1,4-phenylenediamine, 4-dibenzylaminobenzaldehyde-N, N-diphenylhydrazone, 4- Dibenzylamino-3-methylbenzaldehyde-N, N-diphenylhydrazone, 4,4'-bis (carbazol-9-yl) bipe Nyl, N, N, N ', N'-tetraphenylbenzidine, N, N'-bis (4-methylphenyl) -N, N'-bis (phenyl) -benzidine, N, N'-bis (3-methylphenyl ) -N, N'-bis (phenyl) benzidine, N, N, N ', N'-tetrakis (4-methylphenyl) benzidine, N, N, N', N'-tetrakis (3-methylphenyl) benzidine , Di (4-dibenzylaminophenyl) ether, N, N'-di (naphthalen-2-yl) -N, N'-diphenylbenzidine, N, N'-di (naphthalen-1-yl) -N , N'-diphenylbenzidine, 1,3-bis (4 (4-diphenylamino) phenyl-1,3,4-oxadiazol-2-yl) benzene ,, N, N'-di (naphthalene- 2-yl) N, N'-di (3-methylphenyl) benzidine, N, N'-di (naphthalen-1-yl) -N, N'-di (4-methylphenyl) benzidine, N, N'-di (Naphthalen-2-yl) -N, N'-di (3-methylphenyl) benzidine, 1,1-bis (4-bis (4-methylphenyl) aminophenyl) cyclohexane, 4,4 ', 4 "-tris (Carbazol-9-yl) -triphenylamine, 4,4 ', 4 "-tris (N, N-diphenylamino) -triphenylamine, N, N'-bis (biphenyl-1-yl) -N, N'-bis (naphth-1-yl) benzidine, 4,4, ', 4 "-tris (N-3-methylphenyl-N-phenylamino ) Triphenylamine, N, N, N ', N'-tetrakis (biphenyl-4-yl) benzidine, 4,4', 4 "-tris (N- (1-naphthyl) -N-phenylamino ) Triphenylamine, 4,4 ', 4 "-tris (N- (2-naphthyl) -N-phenylamino) triphenylamine, etc. can be used individually or in combination of 2 or more types by a fixed ratio. Of these, tetraphenylbutadiene derivatives are most preferred.

Suitable binder resins for the charge transport layer (CTL) include polyvinylbutylal resin, polyvinylalcohol resin, polyamide resin, polyvinylacetate resin, polyvinylchloride resin, polyacrylic resin, polyurethane resin, polycarbonate resin, polymeth Acrylic resin, polyvinylidene chloride resin, polystyrene resin, styrene-butadiene copolymer resin, styrene-methacrylic acid methyl resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinylacetate copolymer resin, vinyl chloride-vinyl Acetate-maleic anhydride copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-vinylacetate copolymer resin, methylcellulose, nitrocellulose, polysilicon resin, silicone-alkyd resin, phenol-formaldehyde resin, cresol-formaldehyde resin, Styrene-alkyd resin, poly-N -Vinylcarbazole resin, polyvinylformal resin, polyhydroxystyrene resin, polynovonyl resin, polycycloolefin resin, polyvinylpyrrolidone resin, poly (2-ethyl-oxazoline) resin, melamine resin, urea Resin, an amino resin, an isocyanate resin, an epoxy resin, etc. can be used individually or in combination of 2 or more types.

In the case of the charge transport layer, the content ratio of the charge transport material and the binder resin may be 1: 3 to 3: 1. Outside the range of the content ratio, electron transport is not smooth or dispersion is difficult. The more preferable content ratio of the charge transport material and the binder resin is 1: 2 to 3: 2.

As said solvent, the same kind as the solvent used for manufacture of the said charge generation layer can be used individually or in combination of 2 or more types.

As said additive, antioxidant, a light stabilizer, an antifoamer, oil, etc. can be used individually or in combination of 2 or more types as appropriate.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred manufacturing method of the photoconductor according to the present invention.

First, a conductive support is prepared, and a charge generating layer coating liquid is coated on the surface of the support. Means for coating the charge generating layer coating liquid on the surface of the support may be various methods such as dipping or spraying. The charge generating layer coating solution may be prepared by adding a charge generating material, a binder resin, a solvent, and an additive in a predetermined ratio as a solution containing a charge generating material. For example, the charge generating material and the binder resin may be added in a ratio of 5: 1 to 1: 3.

Then, the support on which the charge generating layer is coated is dried. Drying for the charge generating layer is suitable in the range of 100 ~ 130 ℃.

Then, the charge transport layer coating liquid is coated on the surface of the support. As the means for coating the charge transport layer coating liquid may be various methods such as dipping or spraying. The charge transport layer coating liquid is a coating liquid containing a charge transport material, and may be prepared by adding the charge transport material, the binder resin, the solvent, and the additive at a predetermined ratio. For example, the charge transport material and the binder resin may be added in a ratio of 1: 3 to 3: 1.

The photosensitive member coated with the coating liquid is dried in two steps. 1 shows a schematic configuration of a drying apparatus according to the present invention.

Referring to the drawings, the photosensitive member 1 loaded on the pallet 2 is first dried while being cooled by the primary cooling fan 4 while passing through the primary constant temperature chamber 3. The cooled photoconductor is washed with its lower part in a state of being bitten by the chuck 5a of the washing tank 5 to remove foreign matter therein. Primary drying is preferably carried out in 50 ~ 10 minutes in the range of 70 ~ 90 ℃. The primary dried photosensitive member 1 is secondary dried while passing through the secondary constant temperature chamber 6 and cooled by the secondary cooling fan 7. The secondary drying is preferably performed for 10 minutes ± 5 minutes in the range of 110 ~ 130 ℃.

The photosensitive member 1 dried in two steps after the charge transport layer coating is dried slowly during the first low temperature drying, so that the residual stress of the solvent decreases, and the residual solvent is removed during the second high temperature drying. The stress is removed so that the crack resistance of the charge transport layer can be greatly improved.

Hereinafter, the present invention will be described in detail through embodiments applied to a negatively charged stacked photosensitive drum, but the present invention is not limited to the embodiments described below.

<Example 1>

CGL coating liquid manufacturing

4.6 parts by weight of the charge generating material Y-type titanyl oxide phthalocyanine, 3.1 parts by weight of polyvinyl butyral resin (# 6000C: DENKI), 81.6 parts by weight of a tetrahydrofuran solvent together with glass beads (1 mm) and a paint shaker Using a ball mill (ball mill) to prepare a dispersion having an average particle size of about 250nm. The dispersion was diluted with 3.8-fold tetrahydrofuran solvent, 0.4 parts by weight of methanol was added as a dispersion stabilizer, and then ultrasonically injected for 30 minutes to prepare a stable coating solution.

CTL coating solution manufacturing

4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone (ANAN CORPORATION) 4.2 parts by weight, 1,1-bis- (para-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene ( ANAN CORPORATION) 4.2 parts by weight, 11 parts by weight of polycarbonate (Idemitsu Kosan), 0.4 parts by weight of dibutylhydroxytoluene (Shibagaiki Corp.) as an antioxidant, 0.04 parts by weight of silicone oil, 55.7 parts by weight of tetrahydrofuran and toluene 24 A solution was prepared in which parts by weight were dissolved together.

Photosensitive member manufacturing

An aluminum drum having an outer diameter of 24 mmφ, a length of 236 mm, and a thickness of 1 mm was immersed in a CGL coating liquid, and the charge generating layer was coated so that the film thickness after drying was 0.4 µm. Next, the CTL coating solution was immersed and dried, and then dried at 90 ° C. for 50 minutes, and then dried at 110 ° C. for 10 minutes to coat the charge transport layer to have a thickness of 20 μm.

<Example 2>

The drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 90 ° C. for 50 minutes and then dried at 120 ° C. for 10 minutes.

<Example 3>

A drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 80 ° C. for 50 minutes and then dried at 120 ° C. for 10 minutes.

<Example 4>

A drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 70 ° C. for 50 minutes and then dried at 120 ° C. for 10 minutes.

Example 5

The drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 70 ° C. for 50 minutes and then dried at 130 ° C. for 10 minutes.

Comparative Example 1

A drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 120 ° C. for 30 minutes.

Comparative Example 2

A drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 120 ° C. for 60 minutes.

Comparative Example 3

A drum was produced in the same manner as in Example 1 except that the charge transport layer coating film was dried at 110 ° C. for 60 minutes.

Crack resistance evaluation test

Since the crack of the photosensitive member elapses with time after manufacture, it is impossible to reproduce the actual situation and test for the occurrence of cracks because it takes a long time. Therefore, in order to accelerate the crack evaluation, the electrophotographic photosensitive member was immersed in n-butanol (BuOH), and visually observed to investigate the time until cracking occurred.

The evaluation results are shown in Table 1.

 division Dry condition Crack occurrence time Example 1  90 ℃, 50 minutes → 110 ℃, 10 minutes  More than 130 hours Example 2  90 ℃, 50 minutes → 120 ℃, 10 minutes  More than 130 hours Example 3  80 ℃, 50 minutes → 120 ℃, 10 minutes  More than 130 hours Example 4  70 ℃, 50 minutes → 120 ℃, 10 minutes  More than 110 hours Example 5  70 ℃, 50 minutes → 130 ℃, 10 minutes  More than 100 hours Comparative Example 1  120 ℃, 30 minutes  2 hours Comparative Example 2  120 ℃, 60 minutes  3 hours Comparative Example 3  110 ℃, 60 minutes  2 hours

Power failure characteristic evaluation test

Each photosensitive drum thus manufactured was subjected to an electrostatic characteristic evaluation test. The electrostatic characteristic evaluation test was conducted with a electrostatic charge tester (PDA-2000LA: QEA Inc.), charged with -6KV to -7KV corona, 1.0 second after 1.0 second, and 1.0 second after 1.0 seconds of 780 nm light with energy of 1.0 μJ / cm2. After discharging the potential of the drum surface with a red LED light source, the electrophotographic circulation process of standing for 1.0 second was repeated 1000 times.

At this time, the initial charge potential made on the drum surface is represented by Vo, the potential of the drum surface after exposure is expressed by VL, and the potential of the drum surface is represented by Vr after 1.0 second of erasing operation. The potential produced on the surface of the drum after the fatigue test was repeated 1000 times. In addition, the energy per unit area (E1 / 2) required to reduce the initial charge potential to 1/2 by scanning 780 nm light into the drum, and the degree of maintaining the potential after 1.0 seconds and 5.0 seconds in the dark state after charging It measured and represented by DD1 and DD5, respectively.

division Electrostatic characteristics Surface potential Image evaluation E1 / 2 E100 DD1 DD5 Vo VL Solid ID Example 1 0.167 0.392 99.1 96.3 968 196 1.19 Example 2 0.165 0.394 99.0 95.8 983 191 1.25 Example 3 0.169 0.394 98.9 95.2 973 192 1.23 Example 4 0.168 0.392 98.8 95.3 973 189 1.21 Example 5 0.170 0.390 98.7 95.1 970 189 1.22 Comparative Example 1 0.171 0.383 99.1 95.2 985 189 1.24 Comparative Example 2 0.185 0.451 98.5 93.4 977 195 1.22 Comparative Example 3 0.181 0.458 98.5 93.8 978 197 1.20  Vo: Surface potential immediately after charging, E1 / 2 (μJ / cm 2): Exposure energy until the surface potential immediately before exposure is 1/2, E100 (μJ / cm 2): Surface potential immediately before exposure is -100V. Exposure energy up to DD5 (%): Surface potential retention after 5 seconds of exposure in the dark room.

As described in Tables 1 and 2 above, the coating film drying condition of the charge transport layer is 50 minutes in the range of temperature 70 ~ 90 ℃, then time is 10 minutes in the range of temperature 110 ~ 130 ℃ (execution) In Examples 1 to 5, cracks did not occur without deteriorating the characteristics of the electrophotographic photosensitive member. In particular, it was found that the performance of the electrophotographic photosensitive member (Example 1), which was dried at 90 ° C. for 50 minutes and then at 110 ° C. for 10 minutes in the coating film drying conditions of the charge transport layer, was the best.

As described above, according to the present invention, in the first low temperature drying, the solvent is slowly dried to lower the residual stress of the solvent, and in the second high temperature drying, the residual solvent is removed, so that the image quality is excellent and cracks do not occur. An electrophotographic photosensitive member could be obtained.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications may be made by those skilled in the art. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

Claims (5)

Conductive support; A charge generating layer coated on the conductive support; And a charge transport layer stacked on the charge generating layer. The charge transport layer is composed of at least a charge transport material, a binder resin and a solvent, the charge transport material is an electrophotographic photosensitive member, characterized in that composed of tetraphenylbutadiene derivative. Applying a coating liquid containing a charge generating material to the surface of the support and then drying to form a charge generating layer; And And applying a coating liquid containing a charge transport material on the surface of the support on which the charge generating layer is formed, followed by drying to form a charge transport layer. In the drying of the charge transport layer, the support is first dried at a low temperature, followed by secondary drying at a high temperature. The method of manufacturing an electrophotographic photosensitive member according to claim 2, wherein the charge transport layer is first dried in a range of 70 to 90 ° C and then dried in a range of 110 to 130 ° C. The method of manufacturing an electrophotographic photosensitive member according to claim 3, wherein the primary drying is performed longer than the secondary drying. The method of claim 4, wherein the first drying is performed for about 50 ± 10 minutes and the second drying is performed for 10 minutes ± 5 minutes.

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