JP4458319B2 - Method for producing electrophotographic photosensitive member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the production how the electronic photosensitive member, and more particularly relates to the production how the electrophotographic photosensitive member having a charge transport layer and a charge generating layer containing the oxytitanium phthalocyanine.
[0002]
[Prior art]
In recent years, as an electrophotographic photosensitive member used for an electrophotographic copying machine or a laser printer, an organic photoconductor material is used because of its advantages such as high safety, suitable for mass production, and low cost. Many are used. Among them, an electrophotographic photosensitive member having a laminated type photosensitive layer in which a charge generation layer and a charge transporting layer are laminated is more improved in sensitivity, so that an organic electrophotographic photosensitive member is currently mainstream.
[0003]
On the other hand, in electrophotographic image formation, digitization of image formation is rapidly progressing in order to obtain a higher quality image and to store an input image or freely edit it. When digitally forming an image, a digital electric signal is converted into an optical signal and input to an electrophotographic photosensitive member. As this light source, laser light or LED light is mainly used. At present, the most frequently used light source has a transmission wavelength of 790 ± 20 nm, and an electrophotographic photosensitive material having sufficient sensitivity in this wavelength region has been developed. Among them, phthalocyanine compounds are comparatively easy to synthesize and many have a sensitivity in a long wavelength range, and thus are widely studied and put into practical use. In particular, examples of high sensitivity include oxytitanium phthalocyanine. For example, JP-A-61-239248, JP-A-62-67094, JP-A-1-17066, JP-A-3-54264. As shown in Japanese Laid-Open Patent Publication No. 3-128973 and the like, those showing many crystal types have been studied.
[0004]
However, these oxytitanium phthalocyanines cannot be said to have sufficient durability stability, such as a decrease in charging potential due to repeated image forming processes such as charging, exposure, development and transfer, and fluctuations in bright part potential. .
[0005]
Further, when light from a fluorescent lamp or the like hits the electrophotographic photosensitive member, a photo memory is generated in that portion, and defects such as image unevenness occur. The conventional electrophotographic photosensitive member is not sufficient for these defects.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a manufacturing method of high sensitivity and initial and repeated use during any potential stability excellent electronic photosensitive member.
[0008]
[Means for Solving the Problems]
In accordance with the present invention, in a method for producing an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer on a conductive support ,
[0009]
( I) a step of preparing a charge generation layer coating by dispersing oxytitanium phthalocyanine with a solvent containing less than an equivalent amount of water with respect to the oxytitanium phthalocyanine;
(Ii) Using the charge generation layer coating material prepared in step (i), a charge generation layer having a moisture content of 1.8% by mass or more and 2.8% by mass or less measured by a moisture vaporization Karl Fischer method. Forming , and
(Iii) A coating solution in which a charge transporting material and a resin having a film-forming property are dissolved is applied onto the charge generation layer formed in step (ii) and dried with hot air at 105 ° C. for 1 hour to form a charge transporting layer. There is provided a method for producing an electrophotographic photosensitive member, comprising the step of forming .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0013]
The moisture content of the charge generation layer in the present invention can be measured by a moisture vaporization Karl Fischer method. Obtaining the moisture content by placing 0.1 g of the charge generation layer peeled off from the conductive support in a nitrogen gas stream into a moisture vaporizer, and heating and releasing the moisture released at 120 ° C. with a Karl Fischer meter. Can do.
[0014]
In the present invention, it is essential that the water content in the charge generation layer formed in step (ii) is 1.8% by mass or more and 2.8 % by mass or less. When dispersing, the water content can be controlled by adding water. When the water content of the charge generation layer was less than 1.8% by mass, the memory characteristics were deteriorated, and when it exceeded 3% by mass, the sensitivity was deteriorated.
[0015]
Further, as the binder resin constituting the charge generating layer, and a water content is preferably 1 mass% or more and 4 wt% or less of the binder resin, particularly preferably selects one 3 mass% or less of the binder resin or 2 The water content of the charge generation layer can be controlled by mixing more than one type of resin to obtain the above water content. The method for measuring the moisture content of the binder resin can be performed in the same manner as the method for measuring the moisture content of the charge generation layer.
[0016]
Next, the electrophotographic photosensitive member used in the present invention will be described.
[0017]
As a constitution of the laminated type photosensitive layer, a structure in which a charge generation layer and a charge transport layer are laminated in this order or in reverse order on a conductive support can be mentioned. Layer order is preferred. Further, a protective layer may be provided on the photosensitive layer for protecting the surface of the electrophotographic photosensitive member.
[0018]
The support used in the present invention may be any one as long as it has conductivity, for example, a metal such as aluminum, copper, chromium, nickel, zinc and stainless steel formed into a drum or sheet, aluminum A metal film such as copper or copper laminated on a plastic film, aluminum, indium oxide or tin oxide deposited on a plastic film, a metal provided with a conductive layer by applying a conductive substance alone or with a binder resin, Examples include plastic film and paper.
[0019]
In addition, when exposure light from a laser beam printer or the like is laser light, a conductive layer may be provided on the support for the purpose of preventing interference fringes due to scattering or covering scratches on the support. This can be formed by dispersing conductive powder such as carbon black or metal particles in a binder resin. The thickness of the conductive layer is preferably 5 to 40 μm, particularly preferably 10 to 30 μm.
[0020]
The charge transport layer of the laminated photosensitive layer is composed of a polycyclic aromatic compound having a structure such as biphenylene, anthracene, pyrene and phenanthrene, a nitrogen-containing ring compound such as indole, carbazole, oxadiazole and pyrazoline, a hydrazone compound, and a styryl compound. and it is formed using a coating solution prepared by dissolving a resin having a charge transport material, such as triarylamine compounds and film-forming properties.
[0021]
Examples of such a film-forming resin include polyester, polycarbonate, polystyrene, and polymethacrylic acid ester. The thickness of the charge transport layer is preferably 5 to 40 μm, particularly preferably 10 to 30 μm.
[0022]
The charge generation layer of the laminated photosensitive layer of the present invention uses oxytitanium phthalocyanine represented by the following structural formula as a charge generation material.
[0023]
[Chemical 1]
[0024]
In the formula, X ¹ , X ² , X ³ and X ⁴ represent Cl or Br, and n, m, l and k are integers of 0 to 4.
[0025]
Among them, it is preferable from the viewpoint of high sensitivity can be obtained using Okishichitani um phthalocyanine showing a I type crystal form. In the charge generation layer, a charge generation material other than phthalocyanine may be used in combination, or an additive may be added.
[0026]
Examples of the binder resin include a polyvinyl butyral resin, a polyester resin, an acrylic resin, a phenoxy resin, a polycarbonate resin, a polyvinyl acetal resin, a polystyrene resin, and a polyarylate resin, and the water content of the charge generation layer is 1.8. to control the following mass% to 3.0 mass%, it is preferable to use a water content of 1 wt% or more than 4% by mass of the binder resin, especially the water content 1 wt% to 3 wt% or less of the binder It is preferable to use a resin. Also, two or more types of a binder resin mixture of water content 1% by mass or more than 4% by mass, preferably it may be 3 wt% or less 1 mass% or more.
[0027]
Proportion of Okishichitani um phthalocyanine and the binder resin in the charge generation layer is 10 mass ratio: 1 to 1: 5 are preferred, especially from 5: 1 to 1: 2 by weight is preferred.
[0028]
Dispersion solvents are organic solvents such as ether solvents such as tetrahydrofuran, n-propyl ether, n-butyl ether and 1,4-dioxane, alcohol solvents such as methanol, ethanol and propanol, and ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone. A solvent is preferable from the viewpoint of dispersibility and crystal type stability. Furthermore, in order to control the moisture content to the above value, it is more preferable to mix water in the organic solvent. The amount of water added is preferably less than an equivalent amount with respect to oxytitanium phthalocyanine, and particularly preferably 1% by mass or more and less than 100% by mass. This dispersion may be used as it is as a coating solution for the charge generation layer, or may be used by mixing with another organic solvent or water.
[0029]
The dispersion treatment is, for example, a treatment performed using a dispersion medium such as glass beads, steel beads, and alumina balls, a milling treatment such as a paint shaker, a sand mill, and a ball mill, a homogenizer, an ultrasonic dispersion, or a high-pressure collision dispersion device. is there.
[0030]
This dispersion can be applied on a conductive support by a method such as dip coating, spray coating, or spiral coating, and a charge generation layer can be formed by a drying oven at 100 ° C. or lower, or by dry-to-touch. At this time, the thickness of the charge generation layer is preferably from 0.01 to 5 μm, particularly preferably from 0.05 to 1 μm.
[0031]
In the present invention, an undercoat layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. The undercoat layer can be formed of polyamide, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, alcohol-soluble amide, polyurethane or gelatin. The thickness of the undercoat layer is preferably 0.1 μm to 3 μm.
[0032]
FIG. 1 shows a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.
[0033]
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. The electrophotographic photosensitive member 1, in the rotation process, positive or on the peripheral surface thereof by a static-unit 3 receives the uniform charging of a predetermined negative potential, then the slit exposure or laser beam scanning exposure or the like of an exposure unit (not shown) The exposure light 4 subjected to intensity modulation corresponding to the time-series electric digital image signal of the target image information to be output 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.
[0034]
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. It is the transfer material 7 which is fed in, the toner over image formed and carried on the surface of the electrophotographic photosensitive member 1 are successively transferred by the transfer means 6.
[0035]
The transfer material 7 which has received the transfer of the toner over image, image formation by being separated from the electrophotographic photosensitive member surface is introduced to an image fixing means 8 receives the image fixing (print, copy) is printed out of the apparatus as The
[0036]
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. Note that when the strip conductor means 3 is a contact charging means using a charging roller or the like, pre-exposure is not necessarily required.
[0037]
In the present invention, the electrophotographic photosensitive member 1 described above, strip conductor means 3, among the components such as the developing means 5 and cleaning means 9, constructed by integrally coupled as a process cartridge pay more of the container 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, strip conductor means 3, at least one of developing means 5 and cleaning means 9 which cartridge integrally supported to form together with the electrophotographic photosensitive member 1, the apparatus main body by using a guiding means 12 such as a rail of the apparatus main body detachable A flexible process cartridge 11 can be obtained.
[0038]
Further, when the electrophotographic apparatus is a copying machine or a printer, the exposure light 4 is reflected or transmitted light from the original, or the original is read by a sensor and converted into a signal, and a laser beam scanning performed according to this signal is performed. The light emitted by driving the LED array or the liquid crystal shutter array.
[0039]
The electrophotographic photosensitive member of the present invention can be used not only for electrophotographic copying machines but also widely applicable to electrophotographic application fields such as laser beam printers, CRT printers, LED printers, FAX, liquid crystal printers, and laser plate making. It is.
[0040]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “part” means “part by mass”.
[0041]
Example 1
50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resol type phenol resin, 30 parts of methoxypropanol, 30 parts of methanol and silicone oil (polydimethylsiloxane polyoxyalkylene copolymer, weight average) A molecular weight 3000) 0.002 part was dispersed in a sand mill apparatus for 2 hours using 1 mmφ glass beads to prepare a coating solution for a conductive layer, and this coating solution was dip coated onto an φ30 mm × 260 mm long aluminum cylinder. And heated at 140 ° C. for 30 minutes to form a conductive layer having a thickness of 20 μm.
[0042]
Next, a solution obtained by dissolving 10 parts of polyamide resin (trade name: Amilan CM-8000, manufactured by Toray Industries, Inc.) in 200 parts of methanol is dip coated, dried at 90 ° C. for 10 minutes, and a film thickness of 0.7 μm. An undercoat layer was formed.
[0043]
Next, it has strong peaks at 9.0 °, 14.2 °, 23.9 ° and 27.1 ° of the Bragg angle (2θ ± 0.2 °) in the characteristic X-ray diffraction of CuKα as a charge generation material. crystal 10 parts of oxytitanium phthalocyanine represented by the following structural formula crystalline (X-ray diffraction diagram FIG. 2),
[0044]
[Chemical formula 2]
[0045]
10 parts of polyvinyl butyral (trade name: BH-S, manufactured by Sekisui Chemical Co., Ltd.), 291 parts of cyclohexanone, 9 parts of distilled water, each in a sand mill apparatus using 400 parts of 1 mmφ glass beads, at 15-30 ° C., After dispersing for 4 hours, it was diluted with 350 parts of ethyl acetate to prepare a coating solution. This coating solution was applied onto the undercoat layer by a dip coating method and dried at 80 ° C. for 10 minutes to form a charge generation layer having a thickness of 0.2 μm after drying.
[0046]
The water content of the charge generation layer was measured by a moisture vaporization type Karl Fischer measuring device (Hiranuma Sangyo Co., Ltd., AQV-200, EV-6) and found to be 1.8% by mass. The moisture content of the binder resin was 1.1% by mass.
[0047]
Next, 9 parts of a compound represented by the following structural formula as a charge transport material,
[0048]
[Chemical 3]
[0049]
1 part of a compound represented by the following structural formula:
[Formula 4]
[0051]
And 10 parts of bisphenol Z-type polycarbonate (trade name: Z-200, manufactured by Mitsubishi Gas Chemical) was dissolved in a mixed solution of 40 parts of dichloromethane / 60 parts of monochlorobenzene. This solution was applied onto the charge generation layer and dried with hot air at 105 ° C. for 1 hour to form a charge transport layer having a thickness of 20 μm.
[0052]
The electrophotographic photoreceptor thus prepared is attached to a modified machine of a laser beam printer (trade name: Laser Jet 4000, manufactured by Hewlett Packard), charged so that the dark part potential becomes −600 V, and the wavelength is 780 nm. The amount of light necessary for the bright part potential (Vl) to be −150 V was measured by irradiating the laser beam, and the sensitivity was obtained.
[0053]
Further, 1000 images were repeatedly printed and endurance tests were performed, and the initial values of dark part potential and bright part potential and values immediately after endurance (Vd and Vl) were measured. Further, after shielding a part of the electrophotographic photosensitive member and irradiating a non-light-shielded part with 1500 Lux fluorescent light for 5 minutes, the bright part potential is measured by the laser beam printer, and the potential difference between the non-light-shielding part and the light-shielding part is measured. ΔVl was evaluated as a photo memory.
[0054]
Vl = non-shielding part Vl-shielding part Vl
[0055]
The results are shown in Table 1.
[0056]
(Example 2)
In Example 1, the electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that the binder resin for the charge generation layer was replaced with polyvinyl butyral resin (trade name: BH-3, manufactured by Sekisui Chemical Co., Ltd.). Fabricated and evaluated. At this time, the moisture content of the charge generation layer was 2.0% by mass, and the moisture content of the binder resin was 2.3% by mass. The results are shown in Table 1.
[0057]
(Example 3)
In Example 1, the binder resin for the charge generation layer was replaced with a 6: 4 mixed resin of polyvinyl butyral resin having a water content of 2.3% by mass and 1.1% by mass in the same manner as in Example 1. An electrophotographic photoreceptor was prepared and evaluated. At this time, the moisture content of the charge generation layer was 2.4% by mass, and the moisture content of the binder resin was 1.7% by mass. The results are shown in Table 1.
[0058]
Example 4
In the charge generation layer coating material of Example 1, the binder resin was a mixed resin of polyvinyl butyral resin (BH-3): polyvinyl acetal resin (trade name KW-1, manufactured by Sekisui Chemical Co., Ltd.) = 95: 5, An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the dispersion solvent was changed to 291 parts of methanol and 9 parts of water, and the diluent solvent was changed to 350 parts of cyclohexanone. At this time, the moisture content of the charge generation layer was 2.8% by mass, and the moisture content of the binder resin was 2.7% by mass. The results are shown in Table 1.
[0059]
(Comparative Example 1)
In Example 1, an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the binder resin was replaced with a polycarbonate resin having a water content of 0.1% by mass. At this time, the moisture content of the charge generation layer was 1.0 mass%. The results are shown in Table 1.
[0060]
(Comparative Example 2)
In the charge generation layer coating material of Example 1, the binder resin was a polyvinyl acetal resin having a water content of 4.8% by mass, the dispersion solvent was replaced with 210 parts of methanol and 90 parts of water, and the diluent solvent was 350 parts of cyclohexanone. Were produced in the same manner as in Example 1 and evaluated. At this time, the moisture content of the charge generation layer was 3.2% by mass. The results are shown in Table 1.
[0061]
(Comparative Example 3)
In Example 1, the crystal of oxytitanium phthalocyanine, except that X-ray diffraction diagram was replaced with crystals of the crystal form of oxytitanium phthalocyanine shown in Figure 3, to produce the electrophotographic photosensitive member in the same manner as in Example 1, Evaluation was performed. The water content of the charge generation layer was 1.3% by mass. The results are shown in Table 1.
[0062]
(Comparative Example 4)
An electrophotographic photosensitive member was produced and evaluated in the same manner as in Example 1 except that the dispersion solvent was changed to only cyclohexanone in the charge generation layer coating material of Example 1. The water content of the charge generation layer at this time was 1.4% by mass. The results are shown in Table 1.
[0063]
[Table 1]
[0064]
【The invention's effect】
The present invention, high sensitivity and initial and potential change after repeated image output is small and it has become possible to provide a manufacturing how the photo memory is smaller electrophotographic photoreceptor.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.
FIG. 2 is a characteristic X-ray diffraction pattern of oxytitanium phthalocyanine of the present invention.
FIG. 3 is a characteristic X-ray diffraction pattern of oxytitanium phthalocyanine used in a comparative example.
[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 (1)

In a method for producing an electrophotographic photoreceptor comprising a charge generation layer and a charge transport layer on a conductive support ,
(I) a step of dispersing the oxytitanium phthalocyanine with a solvent containing less than an equivalent amount of water relative to the oxytitanium phthalocyanine to prepare a coating for a charge generation layer;
(Ii) Using the charge generation layer coating material prepared in step (i), a charge generation layer having a moisture content of 1.8% by mass or more and 2.8% by mass or less measured by a moisture vaporization Karl Fischer method. Forming , and
(Iii) A coating solution in which a charge transporting material and a resin having a film-forming property are dissolved is applied onto the charge generation layer formed in step (ii) and dried with hot air at 105 ° C. for 1 hour to form a charge transporting layer. And a process for forming the electrophotographic photosensitive member.