JP4227514B2 - Electrophotographic photosensitive member, process cartridge having the electrophotographic photosensitive member, and electrophotographic apparatus - Google Patents

Description

  The present invention relates to an electrophotographic photosensitive member and an electrophotographic apparatus provided with the electrophotographic photosensitive member, and more particularly, to an electrophotographic photosensitive member having a photosensitive layer having an electron transport ability and containing a high molecular compound having a specific structure. The present invention relates to a process cartridge containing an electrophotographic photosensitive member and an electrophotographic apparatus.

  The electrophotographic photoreceptor is required to have high image quality without sensitivity, electrical characteristics, optical characteristics and image defects according to the applied electrophotographic process, and in any environment from low temperature and low humidity to high temperature and high humidity. In addition, it is required to have an environment in which the characteristics are sufficiently exhibited even in repeated use over a long period of time and stability to repeated use.

  The electrophotographic photosensitive member is basically composed of a conductive support and a photosensitive layer having photoconductivity, and the photosensitive layer is a so-called laminated type that is a function-separated type including a charge generation layer and a charge transport layer. The electrophotographic photosensitive member is classified into a so-called single layer type electrophotographic photosensitive member having a charge generation function and a charge transport function in the same layer.

  In the case of a multilayer electrophotographic photoreceptor, the charge generation layer is composed of a charge generation material having a charge generation function and a binder resin, and the charge transport layer is composed of a charge transport material having a charge transport function. In the electrophotographic process, charges generated in the charge generation layer by exposure, that is, holes and electrons, are ideally injected and moved to the charge transport layer and the conductive support according to an electric field, respectively. For example, in the process of negatively charging the photosensitive layer side, holes generated in the charge generation layer are injected and moved to the charge transport layer, and electrons generated in the charge generation layer are injected and moved to the conductive support. However, in reality, the charge generated in the charge generation layer cannot be completely injected and moved into the charge transport layer or the conductive support, and is trapped in the charge generation layer or at the interface between the charge generation layer and the charge transport layer or intermediate layer. And accumulated by repeated use. As a result, for example, electrical characteristics such as increase in residual potential, change in dark and bright potentials, increase in dark attenuation, and image quality such as ghost and fog are caused by repeated use. As a method for suppressing charge trapping in the charge generation layer, for example, Patent Document 1 and Patent Document 2 propose that the charge generation layer contains a charge transporting substance or an electron withdrawing substance, and the effect thereof is shown. Has been.

JP-A-6-180509 JP 2000-39730 A

  However, the photosensitive layer is composed of a charge generation material, an organic compound having a relatively low molecular weight as an electron transport material, and a binder resin. In this photosensitive layer, since the binder resin is present in the charge generation layer, there is a limit to the amount of the electron transport material that can be added. There is. In the case of a multilayer electrophotographic photosensitive member, when forming a charge transport layer on a charge generation layer, depending on the solvent of the charge transport layer solution, the molecular weight of the electron transport material is small, so that part of the electron transport material is an electron. It may elute into the transport layer, limiting the choice of solvent when forming the charge transport layer. In particular, in the case of dip coating, problems such as elution of the electron transport material into the charge transport layer solution occur.

  An object of the present invention is to provide an electrophotographic photosensitive member that exhibits stable potential characteristics and can continuously form excellent images at the time of repeated use in all environments from low temperature and low humidity to high temperature and high humidity. An object is to provide an electrophotographic photoreceptor excellent in production stability.

  Another object of the present invention is to provide a process cartridge and an electrophotographic apparatus having the above electrophotographic photosensitive member.

The present invention provides a multilayer electrophotographic photoreceptor having a photosensitive layer comprising a charge transport layer comprising a charge generating layer a charge transport material comprising a conductive substrate conductive and load generating material and an electron transporting polymer compound, The electron transporting polymer compound has a repeating structural unit represented by the following formula (2), and the electron mobility of the electron transporting polymer compound is 1 × 10 ^{−8 to} 1 × 10 ⁻⁵ cm ^2. An electrophotographic photosensitive member characterized by being in the range of / V · sec .

(In the formula (2), _{X 2} is configured et al or alkylene group, an arylene group or an ether group,, _{A 2} is a structure having an electron transport property selected from the following formulas (3) to (5) and (7) Unit is shown, and n is 0 or 1.)

(In formula (3), Y represents an aryl group which may have a substituent.)

Further, it is preferable that the charge generating material is an electrophotographic photosensitive member is a titanylphthalocyanine pigment or hydroxygallium phthalocyanine Pigment.

  Further, the present invention integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, an image exposure means, a developing means, and a cleaning means, and is attached to and detached from the electrophotographic apparatus main body. It is a process cartridge characterized by being possible.

  The present invention also provides an electrophotographic apparatus comprising the electrophotographic photosensitive member, a charging unit, an image exposing unit, a developing unit, and a transfer unit.

  In the electrophotographic photoreceptor of the present invention, since the electron transporting polymer compound in the charge generation layer also serves as the binder resin, there is no need for a separate binder resin, and the density of the electron transport material increases. Therefore, the electrons generated in the charge generation layer are efficiently injected and moved by the electron transporting polymer compound toward the conductive support, so that electron traps in the charge generation layer and at the interface are reduced, and charge generated by repeated use is reduced. Accumulation also decreases.

  On the other hand, the holes generated in the charge generation layer are also freed from electrostatic binding due to less trapping and accumulation of electrons, and the injection and movement into the charge transport layer are promoted, resulting in the reduction and repetition of the residual potential. A great effect is seen in stabilization of electrophotographic characteristics such as suppression of potential fluctuation in use.

  In addition, since the electrophotographic photosensitive member of the present invention contains a polymer compound as an electron transport material in the charge generation layer, elution or dip coating on the charge transport layer when forming the charge transport layer on the charge generation layer. In this case, elution of the electron transport material into the charge transport layer solution is eliminated, and production stability is greatly improved.

  As described above, according to the present invention, in all environments from low temperature and low humidity to high temperature and high humidity, it has excellent potential characteristics and image characteristics with respect to environmental stability and stability due to repeated use, and production. An electrophotographic photoreceptor excellent in stability, a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor can be provided.

  The photosensitive layer of the electrophotographic photoreceptor of the present invention includes a single layer type containing a charge generating material and a charge transporting material in the same layer, and a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material. Although it is divided roughly into the laminated type which has, any case may be sufficient.

The electron transporting polymer compound containing the repeating structural unit represented by the above formula (2) contained in the photosensitive layer of the present invention is synthesized, for example, by a reaction of polyvinyl alcohol and an aldehyde compound represented by the following formula. It is not limited to reaction.

  The degree of acetalization of the electron transporting polymer compound containing the repeating structural unit represented by the above formula (2) was measured according to the method described in Japanese Industrial Standard K6728 (Testing method for polyvinyl butyral). The degree of acetalization of the electron transporting polymer compound of the present invention is preferably 50 mol% or more, particularly preferably 70 to 90 mol%. Furthermore, the saponification degree of polyvinyl alcohol which is a raw material of the electron transporting polymer compound of the present invention is preferably 85% or more.

  The electron transporting polymer compound of the present invention preferably has a weight average molecular weight in the range of 1,000 to 1,000,000, more preferably in the range of 5,000 to 1,000,000, particularly 10,000. It is preferably in the range of ~ 500,000.

  In addition, the binder resin in the charge generation layer can be mixed with an electron transporting polymer compound if necessary. Examples of the binder resin in the charge generation layer include polycarbonate, polyester, benzal resin, polyamide, phenol resin, polyimide, and polyamic acid.

The electron transporting polymer compound contained in the charge generation layer of the present invention has an electron transport ability, and its electron mobility is 1 × 10 ^{−8 to} 1 × 10 5 under an electric field condition of 100 V / μm. It is in the range of ⁻⁵ cm ² / V · sec , and preferably 1 × 10 ^{−6 to} 1 × 10 ⁻⁵ cm ² / V · sec .

Specific examples of the electron transporting polymer compound of the present invention are listed in Tables 1 and 2 . However, the electron transporting polymer compound of the present invention is not limited to the following exemplified compounds.

  Examples of charge generation materials include azo pigments such as monoazo, disazo and trisazo, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, indigo pigments such as indigo and thioindigo, and perylenes such as perylene acid anhydride and perylene imide. Examples include pigments, polycyclic quinone pigments such as anthanthrone and pyrenequinone, squarylium dyes, pyrylium, thiopyrylium salts, triphenylmethane dyes, and the like. Phthalocyanine pigments and azo pigments are preferred.

  Examples of the charge transport material include polycyclic aromatic compounds such as pyrene and anthracene, carbazole, indole, imidazole, oxazole, thiazole, oxadiazol, pyrazole, pyrazoline, thiadiazol , And heterocyclic compounds such as triazole, hydrazone compounds such as p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, N, N-diphenylhydrazino-3-methylden-9-ethylcarbazole, α-phenyl-4 Styryl compounds such as' -N, N-diphenylaminostilbene, 5- [4- (di-p-tolylamino) benzylidene] -5H-dibenzo [a, d] dichloroheptene, benzidine compounds, triarylmethane compounds, Triphenylamine or a group consisting of these compounds as the main chain or side chain A polymer - (such as poly -N- vinylcarbazole - le, polyvinyl anthracene and the like).

  The charge generation layer is formed by dissolving a charge generation substance in a solvent together with the specific resin and applying it, and the film thickness is preferably 5 μm or less, particularly preferably 0.01 to 1 μm. The charge transport layer is formed by dissolving the charge transport material in a solvent together with the specific resin and coating it, and the film thickness is preferably 5 to 40 μm, particularly preferably 15 to 30 μm.

  As the conductive support, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, titanium, nickel, indium, gold, platinum, or the like is used. Also, plastics (for example, polyethylene, polypropylene, polyvinyl chloride and polyethylene terephthalate, acrylic resin, etc.) or conductive particles (for example, carbon black, silver particles, etc.) in which the above metal or alloy is formed by vacuum deposition. And a support obtained by coating a plastic or metal support with a suitable binder resin, or a support obtained by impregnating plastic or paper with conductive particles.

  The electrophotographic photoreceptor of the present invention may have an intermediate layer as a barrier layer between the conductive support and the photosensitive layer, and examples of the intermediate layer include polymer compounds such as polyamide, polyester and phenol resin. Alternatively, a conductive intermediate layer in which a conductive material such as tin oxide, zinc oxide, or carbon black and a polymer compound are dispersed together may be used. Further, the intermediate layer in the present invention may be composed of only one layer or may be composed of a plurality of functionally separated layers.

  In the electrophotographic photoreceptor of the present invention, a resin layer or a resin layer containing conductive particles may be laminated as a protective layer on the photosensitive layer.

  The various layers described above are applied by, for example, a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, and a beam coating method. It can carry out by arbitrary coating methods, such as.

  The electrophotographic photosensitive member of the present invention can be used not only for electrophotographic copying machines, but also for laser beam printers, CRT printers, LED printers, liquid crystal printers, laser plate making, facsimiles, etc. It can be widely used in electrophotographic application fields.

  The present invention also comprises an electrophotographic apparatus provided with the electrophotographic photosensitive member of the present invention.

  FIG. 1 shows a schematic configuration of an electrophotographic apparatus having a process cartridge having the electrophotographic photosensitive member of the present invention.

  In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member of the present invention, which is rotationally driven around a shaft 2 in a direction indicated by an arrow at a predetermined peripheral speed. In the rotating process, the electrophotographic photosensitive member 1 is charged uniformly (positive or negative) by a charging means (primary charging means) 3 on its peripheral surface, and then exposed to exposure means (such as slit exposure or laser beam scanning exposure). The exposure light 4 that is emphasized and modulated corresponding to the time-series electric digital image signal of the target image information output from the not-shown image is received. In this way, electrostatic latent images corresponding to the target image information are sequentially formed on the peripheral surface of the electrophotographic photoreceptor 1.

  The formed electrostatic latent image is then developed with toner by the developing means 5 and is taken out from a paper feeding unit (not shown) between the electrophotographic photoreceptor 1 and the transfer means 6 in synchronism with the rotation of the electrophotographic photoreceptor 1. The toner image formed and supported on the surface of the electrophotographic photosensitive member 1 is sequentially transferred by the transfer means 6 onto the transferred transfer material 7.

  The transfer material 7 that has received the transfer of the toner image is separated from the surface of the electrophotographic photosensitive member, introduced into the image fixing means 8, and subjected to image fixing to be printed out as an image formed product (print or copy). .

  After the image transfer, the surface of the electrophotographic photosensitive member 1 is cleaned by removing the transfer residual toner by the cleaning unit 9, and is further subjected to charge removal processing by the pre-exposure light 10 from the pre-exposure unit (not shown). Used repeatedly for image formation.

  The charging unit 3 may be a scorotron charger or a corotron charger using corona discharge, or a contact type charger using a known form such as a roller shape, a blade shape, or a brush shape. As a material of the member of the contact charger, an elastic body imparted with conductivity is generally used. The voltage applied to the contact charging member may be only a DC voltage or an oscillating voltage obtained by superimposing an AC voltage on a DC voltage. The oscillating voltage referred to here is a voltage whose voltage value periodically changes with time, and the AC voltage has a peak-to-peak voltage that is at least twice the charging start voltage of the electrophotographic photosensitive member when only the DC voltage is applied. It is preferable.

  When the charging unit 3 is a contact charging unit using a charging roller or the like, pre-exposure is not always necessary.

  In the present invention, a plurality of components such as the electrophotographic photosensitive member 1, the charging unit 3, the developing unit 5, and the cleaning unit 9 described above are housed in a container 11 and integrally combined as a process cartridge. The process cartridge may be configured to be detachable from an electrophotographic apparatus main body such as a copying machine or a laser beam printer. For example, at least one of the charging unit 3, the developing unit 5, and the cleaning unit 9 is integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge, and is detachable from the apparatus main body using a guide unit 12 such as a rail of the apparatus main body. Process cartridge.

  Further, when the electrophotographic apparatus is a copying machine, the exposure light 4 is reflected light or transmitted light from the original, or the original is read by a sensor, converted into a signal, laser beam scanning performed in accordance with this signal, LED Light emitted by driving the array and driving the liquid crystal shutter array.

Example 1
120 parts by weight of a powder composed of barium sulfate fine particles having a tin oxide coating layer (coverage: 50 wt%, powder specific resistance: 700 Ωcm) and resol type phenol resin (Pryofen J-325, manufactured by Dainippon Ink and Chemicals, solid A solution consisting of 70 parts by weight and 100 parts by weight of 2-methoxy-1-propanol was dispersed with a ball mill for about 15 hours. The average particle size of the filler contained in this dispersion was 0.25 μm.

  The dispersion was applied on an aluminum cylinder (outer diameter 30 mm × length 357.5 mm) by a dipping method, and heat-cured at 150 ° C. for 20 minutes to form a conductive intermediate layer having a thickness of 15 μm.

  Next, a solution obtained by dissolving 10 parts by weight of a copolymer nylon resin (Amilan CM8000, manufactured by Toray) in a mixed solution of 60 parts by weight of methanol, 30 parts by weight of butanol, and 10 parts by weight of benzyl alcohol is dip coated on the intermediate layer. And dried by heating at 100 ° C. for 10 minutes to form a barrier layer having a thickness of 0.8 μm.

Next, a solution comprising 4 parts by weight of an oxytitanium phthalocyanine pigment, 2 parts by weight of the polymer compound of Exemplified Compound 9 and 34 parts by weight of cyclohexanone was dispersed in a sand mill for 5 hours, and then 60 parts by weight of tetrahydrofuran was added to form a charge generating layer. A dispersion was prepared. This dispersion was applied onto the barrier layer by dip coating and dried by heating at 70 ° C. for 10 minutes to form a charge generation layer. The film thickness of the charge generation layer was about 0.1 μm.

  Next, 40 parts by weight of a triarylamine compound represented by the following formula (9) and 60 parts by weight of bisphenol Z-type polycarbonate resin (Iupilon, Z-200, manufactured by Mitsubishi Gas Chemical Co., Ltd.) are added to 400 parts by weight of monochlorobenzene. The solution dissolved in 1 was dip-coated on the charge generation layer and dried by heating in an atmosphere at 120 ° C. for 1 hour to form a charge transport layer having a thickness of 24 μm, thereby producing an electrophotographic photosensitive member.

The obtained electrophotographic photosensitive member is mounted on a reversal development type copying machine having a charging-exposure-development-transfer-cleaning process (GP-40 remodeling machine manufactured by Canon; exposure amount adjusted to 0.28 μJ / cm ² ). The potential (dark part potential V _D , bright) under the low temperature and low humidity (15 ° C., 10% RH), normal temperature and normal humidity (25 ° C., 40% RH) and high temperature and high humidity (30 ° C., 85% RH) environment. Part potential V _L ) Evaluation and potential fluctuation amount (ΔV) before and after repeating charging and exposure for 3 hours in a low temperature and low humidity environment were obtained. The evaluation results are shown in Tables 3 and 4 .

(Example 2 )
An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the electron transporting polymer compound of the present invention of Example Compound 15 was used for the charge generation layer, and electrophotographic characteristics were obtained in the same manner as in Example 1. evaluated. The evaluation results are shown in Tables 3 and 4 .

(Example 3 )
An electrophotographic photosensitive member was produced in the same manner as in Example 1 except that the charge generating material was changed from an oxytitanium phthalocyanine pigment to a hydroxygallium phthalocyanine pigment and the production conditions shown below were changed. Was used to evaluate the electrophotographic characteristics.

A mixture of 6 parts by weight of a hydroxygallium phthalocyanine pigment, 3 parts by weight of the polymer compound of Exemplified Compound 10 and 40 parts by weight of cyclohexanone was dispersed in a sand mill for 10 hours, and then 60 parts by weight of tetrahydrofuran was added to the dispersion for the charge generation layer. to prepare a said dip coated on the intermediate layer, and further forming a charge generating layer of dried film thickness of about 0.1 [mu] m 10 minutes at 100 ° C.. The evaluation results are shown in Tables 3 and 4 .

(Example 4 )
Except for using the electron transporting polymer compound of the present invention exemplified compounds 14 to the charge generating layer to produce the electrophotographic photosensitive member in the same manner as in Example 3, the electrophotographic properties in the same manner as in Example 3 evaluated. The evaluation results are shown in Tables 3 and 4 .

(Comparative Examples 1 and 2)
Electrophotography in the same manner as in Example 1 and Example 3 except that the electron transporting polymer compound of the present invention was changed to polyvinyl butyral resin (trade name: BX-1, manufactured by Sekisui Chemical Co., Ltd.). A photoconductor was prepared and electrophotographic characteristics were evaluated by the same method as in Example 1. The evaluation results are shown in Tables 3 and 4.

(Comparative Example 3)
6 parts by weight of a hydroxygallium phthalocyanine pigment, 1 part by weight of a polyvinyl butyral resin (trade name: BX-1, manufactured by Sekisui Chemical Co., Ltd.), an electron transporting low molecular weight compound having a structure represented by the following formula (10) After a mixed solution composed of 2 parts by weight and 40 parts by weight of cyclohexanone was dispersed by a sand mill for 10 hours, 60 parts by weight of tetrahydrofuran was added to prepare a dispersion for a charge generation layer, and dip-coated on the intermediate layer. except that then dried for 10 minutes at 100 ° C. to form a charge generating layer having a thickness of about 0.1 [mu] m to prepare an electrophotographic photoreceptor in the same manner as in example 3, the electrophotographic the same manner as in example 1 Characteristics were evaluated. The evaluation results are shown in Tables 3 and 4 .

1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having the electrophotographic photosensitive member of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Axis 3 Charging means 4 Exposure light 5 Developing means 6 Transfer means 7 Transfer material 8 Fixing means 9 Cleaning means 10 Pre-exposure light 11 Process cartridge 12 Guide means

Claims (4)

In the laminated type electrophotographic photoconductor having a photosensitive layer comprising a charge transport layer comprising a charge generating layer a charge transport material comprising a conductive substrate conductive and load generating material and an electron transporting polymer compound, electron transporting property The polymer compound has a repeating structural unit represented by the following formula (2), and the electron mobility of the electron transporting polymer compound is 1 × 10 ^{−8 to} 1 × 10 ⁻⁵ cm ² / V. An electrophotographic photosensitive member characterized by being in the range of sec .

(In the formula (2), X ₂ is composed of an alkylene group, an arylene group or an ether group,, A ₂ is represented by the following formula (3) to (5) and (7) a structural unit having an electron transport property selected from And n is 0 or 1.)

(In formula (3), Y represents an aryl group which may have a substituent.)

The electrophotographic photosensitive member according to claim 1, wherein the charge generating material is a titanylphthalocyanine pigment or hydroxygallium phthalocyanine Pigment. 3. The electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, an image exposure means, a developing means and a cleaning means are integrally supported, and the main body of the electrophotographic apparatus is provided. A process cartridge which is detachable. The electrophotographic photosensitive member according to claim 1 or 2, charging means, image exposure means, the electrophotographic apparatus, characterized in that it comprises a developing means and a transfer means.

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