JPH0285863A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent white fog and black spots even in reversal developing process and to enhance friction resistance by incorporating a binder resin having a specified dielectric constant and trifluorochloroethylene resin particles in the surface layer of a photosensitive body. CONSTITUTION:A lubricant powder or a metallic oxide powder is dispersed into the surface layer of the electrophotographic sensitive body in order to enhance friction resistance, because the surface undergoes repeated rubbing treatment of cleaning processes necessary for image forming, but when the difference in the dielectric constant between the powder and the resin is large, dispersions of microscopic potential acceptance and dark decay in the bulk of the photosensitive layer cause fog in the white background and black spots, especially, in the case of the reversal developing process. The problems can be solved by using trifluorochloroethylene resin as the lubricant additive in an amount of 1 - 20wt.% of the solid weight of the surface layer, and using a silicone resin, a vinylidene chloride resin, or the like having a dielectric constant of 2.8 + or - 0.3 as the binder resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor that is used in a reversal development process and has excellent durability and cleanability.

[Conventional technology]

In recent years, many IT electrophotographic photoreceptors have been put into practical use using organic compounds as photoconductors. In most of these photoreceptors, a relatively low-molecular photoconductive substance is dissolved or dispersed in a binder resin, and then a film is formed to provide a device.

By the way, an electrophotographic photoreceptor generally undergoes a process necessary for image formation in an electrophotographic apparatus. Among these processes, the cleaning process is a factor that limits the life of the electrophotographic photoreceptor. In the cleaning process, the surface of the photoreceptor is rubbed with a rubber blade or the like to remove residual toner that has not been transferred. - On the other hand, as mentioned above, since the photosensitive layer is formed using a binder resin as a structural material, it generally lacks mechanical durability and is susceptible to wear and resulting scratches due to repeated cleaning processes. .

Therefore, electrophotographic photoreceptors using organic compounds have the disadvantage that their durability and lifespan are insufficient.

As a countermeasure to this problem, a method was developed in which lubricating powder (e.g., tetrafluoroethylene resin) or metal oxide powder (e.g., At203) was dispersed in the surface layer in order to improve the printing durability of the photoreceptor surface. and some of them have been put into practical use.

By the way, electrophotographic devices using electrophotographic photoreceptors include general copying machines, copying machines with digital image processing functions, and laser beam printers such as LED f-link and LCD f-link used as output for computers, facsimiles, etc. etc.

In the case of these digital copying machines and printers, image input is performed in negative form, so the process of developing the electrostatic latent image is reversal development. That is, a developer having the same polarity as the latent image is used. In this type of development system, the dark areas of the latent image correspond to the white areas of the hard copy, so microscopic variations in chargeability and dark decay in the bulk of the photosensitive layer tend to appear as capri or black spots on the white background. It has characteristics. Therefore, as mentioned above, if a photoreceptor that has a surface layer with a lubricant dispersed therein to improve durability is used in the reversal development process, capri and black spots will occur more often than when the photoreceptor does not contain a lubricant. It's easy to do.

There are several possible reasons for this, one of which is due to the difference in attraction between the binder resin forming the surface layer and the lubricant dispersed in the microscopic band 11.
It is conceivable that differences occur in the optical power and dark attenuation. That is, the dielectric constant of a binder resin that is practical for forming a photosensitive layer is around 3, whereas the dielectric constant of tetrafluoroethylene resin or polyethylene, which is a typical lubricating additive, is 2 to 2.3. ,
In the case of metal oxides, it is around 10 for At203. Therefore, even if the state of dispersion is good, unevenness will occur in the microscopic electrical properties.

In addition, in the regular development process in a general copying machine, the latent image is developed in the dark area, so fine irregularities in physical properties usually occur.
It does not appear as an image at all.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and to provide a photoreceptor having excellent printing durability and free from any damage caused by white spots or black spots even in a reversal development process.

[Means to solve the problem]

The electrophotographic photoreceptor of the present invention has a surface layer of 2.8±0,3
The present invention is characterized by containing gold-containing binder resin and trifluorochlorinated ethylene resin particles having insufficiency of induction.

The binder resin used in the present invention has a dielectric constant of 2.8±0.3, and examples thereof include the following resins.

The resin used in the present invention is not limited to 0 as shown in these examples, and as long as the dielectric constant is within the range of 2.8±0.3, other resins or copolymerization or polymerization between the exemplified resins may be used. A V-dot etc. can also be used.

The trifluorochloride ethylene resin used in the present invention has a higher dielectric wL factor (around 2.8 at low frequencies) than other fluorine-containing polyethylene resins with lubricating properties, and is commonly used as a binder resin for photosensitive layers. It has a number Mk very close to that of the material used in

Ethylene trifluoride resin is polyvinylidene chloride in which all hydrogen has been replaced with fluorine, and although its function as a lubricant is inferior to ethylene tetrafluoride, it can be added to the surface layer. By adjusting the amount, it is possible to obtain sufficient durability as a Shimiko photographic photoreceptor.

In addition, the addition of such a lubricant has an additional effect of lowering the frictional resistance with the cleaning blade, and reducing the blade V.
- It is possible to prevent the reversal of the code.

If the blade is reversed, it cannot be returned to its original state unless the child photographic photoreceptor is removed from the electrophotographic apparatus, which requires a very complicated operation, so preventing this reversal is extremely effective.

The trifluorochloroethylene resin used in the present invention is preferably in powder form, and the particle size is preferably about 0.1μ or less in terms of primary particles.If the particle size is large, the film formation will become uneven. image defects are likely to occur. Incidentally, a dispersion aid may be added to achieve more uniform particle dispersion.

As the dispersion aid, a surfactant containing a fluorine atom is preferred.

The amount of trifluorochloroethylene resin added to the surface layer is suitably 0.5 to 40%, particularly preferably 1 to 20%, based on the solid weight of the surface layer.

If the amount added is less than 0.5%, the effect of improving printing durability is not sufficient, whereas if it exceeds 40% gold, the photoconductive material concentration decreases, light transmittance decreases, etc., which impairs the generation and transport of photocarriers.
This is not desirable as it may cause damage.

In the present invention, the surface layer corresponds to a charge transport layer or a charge generation layer in the case of a laminated photoreceptor, depending on the order of lamination. Further, when a protective film is provided on these photosensitive layers, this protective film becomes a surface layer. The main material forming these surface layers is the aforementioned resin having a dielectric constant within a certain range. When forming the surface layer, first the resin and trifluorochloroethylene resin are dispersed together with a solvent using a known dispersion means such as a sand mill, mail mill, homogenizer, vibrating sand mill, ultrasonic wave, attritor roll mill, etc. In the case of a charge transporting layer or a charge generating layer, a paint is prepared by further dissolving or dispersing a charge transporting material or a charge generating material therein. This coating 11t-dipping method,
A film is formed by coating and drying using a known molding method such as a spray method, a beam method, a printed V-coat, or a spinner cord.

Next, a specific embodiment of an electrophotographic photoreceptor will be described in which a charge generation layer and a charge transport layer are laminated in this order on a conductive substrate.

As the conductive substrate, the substrate itself is conductive, such as aluminum or aluminum alloy.

Substrates composed of copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium, gold, platinum, etc. can be used, as well as aluminum,
Aluminum alloy, indium oxide, tin oxide, innomium oxide modified tin alloy, etc. A layer formed by full vacuum deposition method? A substrate made of a glass material (for example, polyethylene, polynolopyrene, polyvinyl chloride, polyethylene terephthalate, acrylic resin, polyfluoroethylene, etc.) can be used.

A subbing layer having both a barrier function and an N-contact function may be provided between the conductive substrate and the photosensitive layer.

Subscript 4 C, casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyvinyl butyral, phenolic resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, It can be formed from gelatin, aluminum oxide, etc.

The thickness of the undercoat layer is 0.1μ to 10μ, preferably 0.1μ to 10μ.
1μ to 3μ is appropriate.

Furthermore, it is preferable to provide a conductive layer between the substrate and the undercoat layer for the purpose of covering unevenness and defects on the substrate, and for preventing interference due to scattering when the image input is a laser beam. . This can be formed by dispersing it in a binder resin on a conductive substrate such as cargo/black, metal particles, metal oxide, etc., applying the dispersion, and drying it. The appropriate thickness of the conductive layer is 5 to 40 microns, preferably 10 to 30 microns. The charge-generating layer contains charge-generating materials such as pyrylium, thiogyrillium dyes, phthalocyanine pigments, anthantrone pigments, dibenzubire/quinone pigments, pyranthrone pigments, trisazo pigments, disazo pigments, azo pigments, indigo pigments, quinacridone pigments, and quinocyanine. It is formed by coating a coating liquid in which the material is dispersed in a suitable binder solution onto a conductive substrate or undercoat layer. Film thickness is 0
．． 05-10μ, preferably 0.1-3μ is suitable.

As the charge transport material, common materials such as pyrazoline compounds, hydrazone compounds, stilbene compounds, triphenylamine compounds, pennosone compounds, and oxidezole compounds can be used. The formation of the charge transport layer is as described above for the formation of the surface layer.

The coating method for each of these layers is also appropriately selected from among the various methods described above. Examples are shown below, but the present invention is not limited by these Examples. In the description of each example, all parts are by weight.

Example 1 An M cylinder of 30φ x 260mm was used as a base. A liquid mixture consisting of the following was applied to this by dipping and heated to 140°C.

It was heat cured for 30 minutes to form an 18μ anti-scattering conductive layer. Next, polyamide resin (product name: Amilan CM-800
A 5% methanol solution of 0.0 (manufactured by Toshi Co., Ltd.) was applied by a dipping method to form a 1 μm subbing layer.

Next, 4 parts of a structural resin (trade name: S-LEC BL-8, manufactured by Miki Kagaku) and 200 parts of cyclohexanone were dispersed for 50 hours using a sand mill device using 1φ glass beads, and 300 to 450 parts of tetrahydrofuran (appropriately ) was added and coated on the undercoat layer to form a 0.15μ charge generation layer.

Then, a charge transport layer coating material was prepared by the following method.

10 parts of styrene-acrylic copolymer resin with a dielectric constant of 3.0 (trade name MS-200, manufactured by Shin Nippon Saitetsu Chemical Co., Ltd.) is dissolved in 50 parts of monochlorobenzene, and trifluoride with a dielectric constant of 2.7 is dissolved in this. 0.8 parts of ethylene resin powder (trade name: Daiflon, manufactured by Daikin Industries) was added and dispersed in a stainless steel DG-Lumil for 50 hours. To this, 1 part of the hydrazone compound of the formula was added and dissolved, and a coating material was applied onto the charge generation layer to form a charge transport layer of 20 microns.

The photoreceptor created in this way is laser beam solinter (
LBP-8X (manufactured by Canon) and the printed image was evaluated.

Comparative Example 1 In Example 1, tetrafluoroethylene resin (trade name: Lublon, manufactured by Daikin Industries) was used instead of trifluorochloroethylene resin.
A photoreceptor was prepared in the same manner except that . Note that the dielectric constant of the tetrafluoroethylene resin was 2.1.

Comparative Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that the trifluorochloroethylene resin was not added.

The evaluation results of these photoreceptors are summarized in Table 1 below.

Table 1 Example 2 An At cylinder of 80φX 3601111 was used as the base.

A conductive layer and an undercoat layer were applied to this in the same manner as in Example 1.

Next, as shown in the structural formula, the photoreceptor of Example 1 based on the present invention obtained good images even after durability, but in Comparative Example 1 in which tetrafluoroethylene was dispersed, the binding Many black spots occur due to the difference in dielectric constant with the resin.

Ta. However, the condition remained almost unchanged even after the durability test.

On the other hand, like this! Comparative example 2 without j4 temperature additive
In this case, the surface layer was severely abraded, and the resulting drop in dark area potential caused fogging, and it could not withstand printing up to 15,000 sheets.

10 parts of trisazo pigment, polyvinyl butyral resin (
4 parts (trade name: Kosurek BL-8, manufactured by Miki Kagaku) and 200 parts of cyclohexane were dispersed for 30 hours in a sand mill device using 1φ glass beads, and 300 to 450 parts of tetrahydrofuran (as appropriate) was added to form an undercoat layer. A charge generation layer of 0.15μ was formed by coating on top.

Next, 10 parts of bisphenol 2 type PolJ car & nate resin having a dielectric constant of 30 was dissolved in 50 parts of monochlorobenzene, and 1 part of trifluoroethylene resin was dispersed therein in the same manner as in Example 1. ) and image evaluation was performed. Initial image and 1000
Good images were obtained even after 0 copies, and the wear on the surface layer was very small (1μ/1oooo page).Also, since the surface layer has excellent lubricity, the cleaning blade does not turn over during copying. However, it showed good leaning properties.

Example 3 An Aj cylinder of 80 φ x 360 mm was used as a base. A conductive layer and an undercoat layer were applied to this in the same manner as in Example 1.

Next, 10 parts of a stilbene compound having the structural formula was added and dissolved to prepare a charge transport layer cloth solution. Apply this on the charge generation layer for 20 minutes.
A charge transport layer of μ was formed. This photoreceptor is used in a color copying machine (CLC-1) that dezotalizes the original image and outputs it as a laser signal, 10 parts of Canon's disazo pigment, and polyvinyl butyral resin (product name: Kosurek BM-2).
, building blocks chemical composition) 5 parts and 200 parts of cyclohexane to 1φ
is dispersed for 30 hours using a sand mill device using Russ beads, and 300 to 450 parts of tetrahydrofuran (as appropriate) is added to this.
was added and coated on the undercoat layer to form a charge generation layer of 0.15μ.

Then, a charge transport layer coating material was prepared by the following method.

Bisphenol A polycarbonate with a dielectric constant of 3.0 (product name: Nipiron E-2000, Mitsubishi Gas Chemical jJ
j) Dissolve 10 parts in 20 parts of monochlorobenzene and 30 parts of dichloromethane, and add 1.2 parts of trifluorochloroethylene resin powder (trade name: Daiflon, manufactured by Daikin Industries) with a dielectric constant of 2.7. The mixture was dispersed in a stainless steel mail mill for 50 hours. This is a microprinter (NP-) '780 manufactured by Canon that can make copies of the original from negative microfilm using this photoreceptor.
and image evaluation was performed. In this case, since the negative is reversed, the development is also reversed.

There was no fog in the image at the initial stage and after running for 5000 sheets, and there were almost no scratches on the surface of the photoreceptor.

No reversal of the cleaning blade occurred during copying.

〔Effect of the invention〕

As described above, the electrophotographic photoreceptor of the present invention has sufficient durability and good image quality even in an electrophotographic apparatus using a reversal development process.

A coating solution containing 10 parts of hydrazo/compound was applied onto the charge generating layer to form a 20 micron charge transport layer.

Agent Patent Attorney Sekihei Yamashita

Claims (1)

[Claims] In an electrophotographic photoreceptor, its surface layer is 2.8±0.3
1. An electrophotographic photoreceptor comprising a binder resin having a dielectric constant and trifluorochloroethylene resin particles.