JPH0375754A - Electrophotograhic sensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity by incorporating a specified biphenyl derivative into a binder resin, and improving sensitization action and repeated use enduring characteristics. CONSTITUTION:The electrophotographic sensitive body contains the biphenyl derivative represented by formula I, in which R is aralkyl, together with an electric charge transfer material in the binder resin. This biphenyl derivative is excellent is sensitization action and repetition enduring chracteristics and enhances the sensitivity of the photosensitive body. This derivative can be used for both of a single layer type or a laminate type, so long as it is used as an additive in various proportions together with the charge transfer material, and electric characteristics excellent in all of sensitization effect, repetition characteristics, and chargeability can be obtained by containing the biphenyl derivative in an amount of 5 - 40 pts.wt. based on 100 pts.wt. of the binder resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic photoreceptor suitably used in an image forming apparatus such as a copying machine.

(Prior Art) In recent years, organic photoreceptors have been used as electrophotographic photoreceptors in image forming apparatuses such as copying machines because they are easy to process and are advantageous in terms of manufacturing cost, and also have a large degree of freedom in functional design. Among them, a photosensitive layer containing a charge-generating material that generates charges upon light irradiation and a charge-transporting material that transports the generated charges, such as a single-layer type in which the charge-generating material and the charge-transporting material are contained in a binder resin. A functionally separated electrophotographic photoreceptor has been proposed, which includes a photosensitive layer and a laminated photosensitive layer in which a charge generation layer containing the charge generation material described above and a charge transport layer containing the charge transport material described above are laminated. .

In addition, when forming a copy image using an electrophotographic photoreceptor, the Carlson process involves a charging process in which the photoreceptor is uniformly charged by corona discharge, and a document image is exposed to light on the charged photoreceptor to form a photoreceptor that corresponds to the original image. an exposure step to form an electrostatic latent image; a development step to develop the electrostatic latent image with a developer containing toner to form a toner image; and a transfer step to transfer the toner image to a base material such as paper. The basic steps include a fixing process to fix the toner image transferred to the substrate, and a cleaning process to remove the toner remaining on the photoreceptor after the transfer process. In order to form an image, an electrophotographic photoreceptor is required to have excellent photosensitive characteristics.

(Problems to be Solved by the Invention) However, in the above-mentioned functionally separated electrophotographic photoreceptor, the characteristics of the materials used, such as the charge-generating material, charge-transporting material, and additives, affect the electrical and photosensitive characteristics of the photoreceptor. Although various materials have been researched and proposed to have a large influence on the photoreceptor, an organic photoreceptor with sufficient photosensitive properties has not yet been obtained. Therefore, an object of the present invention is to provide an electrophotographic photoreceptor with high sensitivity by using a biphenyl derivative having excellent sensitizing action and repeatability.

(Means and effects for solving the problems) The present invention has the following features:
The above objective can be achieved by comprising an electrophotographic photoreceptor having a layer containing a biphenyl derivative represented by the following formula (1) (wherein R represents an aralkyl group) in a binder resin together with a charge transport material. achieved.

As a result of intensive research, the present inventors found that biphenyl derivatives are extremely good additives.

(Preferred Embodiment of the Invention) An important feature of the present invention is to provide an electrophotographic photoreceptor having a layer containing a biphenyl derivative in a binder resin together with a charge transporting material.

The biphenyl derivative used in the present invention is represented by the following formula [■] (in the formula, R represents an aralkyl group), and the aralkyl group has a carbon number such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, etc. It has a benzene ring at the side end of 1 to 4 lower alkyl groups, and the benzene ring may have a substituent, and examples of the substituent include methyl, ethyl, n-propyl, Examples include lower alkyl groups having 1 to 4 carbon atoms such as isopropyl, n-butyl, and isobutyl, halogen atoms such as fluorine, chlorine, bromine, and iodine atoms, and lower alkoxyl groups such as methoxy and ethoxy groups.

Among these, parabenzylbiphenyl, in which R is a benzyl group having a benzene ring at the side end of the methyl group, is particularly preferred.

The compound represented by the above formula (11) can be applied to either a so-called single layer type or a laminated type electrophotographic photoreceptor as long as it is used together with a charge transporting material.

To make a single-layer electrophotographic photoreceptor, a photosensitive layer containing a biphenyl derivative represented by the above formula (1) as an additive, a charge generating material, and a charge transporting material in a binder resin is attached to a conductive substrate. It can be formed on top.

In addition, in order to obtain a laminated electrophotographic photoreceptor, a charge generation layer containing the charge generation material described above is formed on a conductive substrate by means such as vapor deposition or coating. A charge transport layer containing a biphenyl derivative represented by CI), a charge transport material, and a binder resin may be formed, or, contrary to the above structure, a charge transport layer similar to the above may be formed on a conductive substrate. Then, a charge generation layer containing the charge generation material may be formed by means such as vapor deposition or coating.

The biphenyl derivative as the additive described above can be used in various proportions as long as it does not inhibit charge transport. 5-60 parts by weight, especially 5-4
Preferably, 0 part by weight is used. If the content of the biphenyl derivative is less than 5 parts by weight with respect to 100 parts by weight of the binder resin, the sensitizing effect and repeatability will decrease, and if it exceeds 60 parts by weight, the charging ability will tend to decrease. Especially 5-4
When used within the range of 0 parts by weight, electrical properties with excellent sensitizing effect, repeatability and charging ability can be obtained.

Regarding the photoreceptor using the above-mentioned biphenyl derivative in the present invention, known materials can be appropriately used as basic constituent materials such as a charge generating material, a charge transporting material, and a binder resin.

Examples of the charge generating materials include selenium, selenium-tellurium, amorphous silicon, pyrylium salts, azo pigments, disazo pigments, anthurone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments, and threne pigments. , toluidine pigments, pyrazoline pigments, perylene pigments, quinacridone pigments, etc., and these pigments may be used singly or in combination of two or more so as to have an absorption wavelength range in a desired region.

In addition, charge transport materials include nitro group, nitroso group,
Electron accepting substances such as cyano groups, for example, tetracyanoethylene, fluorenone compounds such as 2,4.7-dolinitro9-fluorenone, dinitroanthracene, 2,4
．． Nitrated compounds such as 8-1-linitrothioxanthone; electron-donating, compounds such as 3,3'-dimethyl-
N, N.

N'', N-tetrakis-4-methylphenyl (1,1
Triphenyldiamine compounds such as '-biphenyl)-4,4'-diamine, N, N.

N'' N l-tetrakis(3-tolyl)-1,3-
Meta-phenylenecyamine compounds such as phenylenedia fruit, N,N-diethylaminobenzaldehyde N,N
- Hydrazone compounds such as diphenylhydrazone, N-methyl-3-carbazolyl aldehyde N, N-diphenylhydrazone, oxadiazole compounds, styryl compounds, pyrazoline compounds, oxazole compounds,
Nitrogen-containing cyclic compounds such as isoxazole compounds, thiazole compounds, imidazole compounds, pyrazole compounds, indole compounds, triazole compounds,
Fused polycyclic compounds such as anthracene, pyrene, phenanthrene, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, ethylcarbazole-
Examples include formaldehyde resin. One or more types of the above charge transport materials may be used.

Various resins can be used as binder resins in the photosensitive layer, charge generation layer, and charge transport layer, such as styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, Styrene
Maleic acid copolymer, acrylic polymer, styrene-acrylic copolymer, polyethylene, ethylene-vinyl acetate copolymer, chlorinated polyethylene, polyvinyl chloride, polypropylene, vinyl chloride-vinyl acetate copolymer, polyester, Alkyd resin, polyamide, polyurethane, polycarbonate, polyarylate, polysulfone,
Thermoplastic resins such as diallyl phthalate resin, ketone resin, polyvinyl butyral resin, polyether resin, silicone resin, urea resin, melanin resin, and other crosslinkable thermosetting resins, as well as epoxy acrylate, urethane-acrylate, etc. Examples include various polymers such as curable resins. These binder resins may be used alone or in combination of two or more.

Further, when forming the charge generation layer and the charge transport layer by coating means, a solvent is used. Various organic solvents can be used as the solvent, including alcohols such as methanol, ethanol, isopropanol, butanol, alcohols such as n-hexane, octane, and cyclohexane,
Aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, Examples include ethers such as ethylene glycol dimethyl ether and ethylene glycol diethyl ether, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formaldehyde, and dimethyl sulfoxide. It is used by mixing more than one species.

Further, when an antioxidant is used in combination, it is possible to suitably prevent deterioration due to oxidation of charge transport materials having a structure susceptible to oxidation.

The above antioxidants include 2,6-tert-phthyl-p-cresol, triethylene glycol-(3-
(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], ■, 6-hexanethiolubis[3(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], pentaerythrityl-tetrakis (3-(3,5-diter)
t-butyl-4-hydroxyphenyl)propionate L
2.2-thiodiethylenebis(3-(3,5-dit)
ert-butyl-4-bitroxyphenyl)propionate), 2,2-thiobis(4-methyl-6-tert)
-butylphenol), N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamado), 1.3.5-)dimethyl-2゜4
．． 6-1-lith(3,5-tert-butyl-4-
Examples include phenolic antioxidants such as hydroxybenzyl)benzene, and among them, 2,6-tert-butyl-p-cresol is preferred.

Various conductive materials can be used as the conductive substrate, such as aluminum, copper, tin, platinum, gold,
Single metals such as silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless copper, and brass, plastic materials on which the above metals are vapor-deposited or coated, aluminum iodide, tin oxide, oxidation Examples include glass coated with indium or the like. The above-mentioned conductive substrate may be either sheet-shaped or drum-shaped, and it is preferable that the substrate itself has conductivity or the surface of the substrate has conductivity and has sufficient mechanical strength when used.

In a laminated photoreceptor, when the charge transporting material is used together with the binder resin, the charge transporting material and the binder resin can be used in various ratios; On the other hand, it is preferable to use 10 to 500 parts by weight, particularly 25 to 200 parts by weight, of the charge transport material. Further, the charge transport layer containing the compound represented by the formula (1) is preferably formed to have a layer thickness of about 2 to 100 μm, particularly about 5 to 30 μm.

When the charge generating material is used with the binder resin,
The charge generating material and the binder resin can be used in various ratios, but it is preferable to use 5 to 500 parts by weight, particularly 10 to 250 parts by weight, of the charge generating material per 100 parts by weight of the binder resin. is preferred. Further, the charge generation layer may have an appropriate layer thickness, but is preferably 0.01 to 3 μm, particularly 0.01 to 3 μm. It is preferably formed to have a thickness of about 1 to 2 μm.

On the other hand, in a single-layer electrophotographic photoreceptor, the charge generating material, the charge transporting material, and the binder resin can be used in various ratios. 2 to 20 parts by weight of generation material, 40 to 20 parts by weight of charge transport material
Preferably, 200 parts by weight are used. Further, the photosensitive layer is preferably formed to have a thickness of about 5 to 60 μm, particularly about 10 to 30 μm.

In order to form each of the above-mentioned photosensitive layers by coating means, each material such as the above-mentioned binder resin is adjusted using a conventionally known method such as a roll mill, a ball mill, an attritor, a paint shaker, or an ultrasonic disperser. , it may be applied and dried by a conventionally known application means.

(Example) Hereinafter, the present invention will be explained in more detail based on Examples.

Example 1 Poly-(4,4°-cyclohexylidene diphenyl)
Carbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name Polycarbonate Z) 100 parts by weight, N, N=di(3,5-dimethylphenyl)perylene-3°4.9.10-tetracarpoxydiimide 8 parts by weight, Type metal-free phthalocyanine (manufactured by Dainippon Ink Co., Ltd.) 0.2 parts by weight, 3.3゛
-dimethyl N, N, N", N゛ -tetrakis-4-methylphenyl (1,1°-biphenyl)-4
, 80 parts by weight of 4°-diamine, 81 parts by weight of parabenzylbiphenyl, 5 parts by weight of antioxidant (manufactured by Kawaguchi Chemical Co., Ltd., trade name: ANTAGE BHT), 0.01 part by weight of polydimethylsiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.), and A fixed amount of tetrahydrofuran was mixed and dispersed using an ultrasonic disperser to prepare a dispersion liquid for a single-layer type photosensitive layer, and the dispersion liquid was coated on an alumite-treated aluminum tube to form a photosensitive layer with a thickness of about 100 μm. An electrophotographic photoreceptor was prepared by heat treatment at ℃.

Example 2 A single-layer electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that 20 parts by weight of parabenzylbiphenyl used in Example 1 was used instead of 8 parts by weight.

Example 3 A single-layer electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 30 parts by weight of parabenzylbiphenyl used in Example 1 was used instead of 8 parts by weight.

Example 4 A single-layer electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 40 parts by weight of parabenzylbiphenyl used in Example 1 was used instead of 8 parts by weight.

Example 5 A single-layer electrophotographic photoreceptor was produced in the same manner as in Example 1, except that 55 parts by weight of parabenzylbiphenyl used in Example 1 was replaced with 8 parts by weight.

Example 6 A coating solution for a charge generation layer was prepared consisting of 100 parts by weight of oxotitanylphthalocyanine, 100 parts by weight of polyvinyl butyral (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka Butyral #500-A), and a prescribed tetrahydrofuran. was applied on an alumite-treated aluminum tube to a thickness of about 1.

A charge generation layer having a thickness of about 0.2 μm was formed by heat treatment at ℃. Then 3,3°-dimethyl-N,
N,N',N'-tetrakis-4-methylphenyl(1,1°-biphenyl)-4°4”-diamine 100
Parts by weight, poly-(4,4° cyclohexylidene diphenyl) carbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name Polycarbonate Z) 100 weight 11 parabenzylbiphenyl 2
A charge transporting coating liquid consisting of 0 parts by weight and a predetermined amount of benzene is prepared, and is applied onto the charge generation layer and heated and dried to form a charge transporting layer with a thickness of approximately 20 μm, and form a layered electron layer. A photographic photoreceptor was created.

Comparative Example 1 A single-layer electrophotographic photoreceptor was produced in the same manner as in Example 1, except that parabenzylbiphenyl used in Example 1 was not added.

Comparative Example 2 In place of parabenzylbiphenyl used in Example 1, 2.
A single-layer electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that 20 parts by weight of 3-dichloro-1,4-naphthoquinone was used.

Comparative Example 3 In place of parabenzylbiphenyl used in Example 6, 2.
A laminated electrophotographic photoreceptor was prepared in the same manner as in Example 6 except that 20 parts by weight of 3-dichloro-1,4-naphthoquinone was used.

[Evaluation of electrophotographic photoreceptor]

The electrophotographic photoreceptors obtained in the above Examples and Comparative Examples were positively or negatively charged using a tram sensitivity tester (manufactured by Dientic Co., Ltd., trade name: Dientic Cynthia 30M), and the photosensitive properties and The surface potential was measured and the results are shown in Table 1.

Exposure time: 60 msec Light source: Halogen lamp Exposure intensity: 0.92 mW In the table, V, , (V) indicates the initial surface potential of the photoreceptor when it is charged under the above conditions, and t El/2
(μJ/cd) is the initial surface potential V, (V
), and the surface potential 0.4 seconds after the start of exposure is the residual potential V□ (V)
It was measured as Furthermore, each of the above-mentioned electrophotographic photoreceptors was used in an electrophotographic copying machine (manufactured by Sanda Kogyo Co., Ltd., product name: DC-llll).
) and the surface potential VIS after repeating the electrophotographic process 1500 times. o-(V) and residual potential VIS. .

IP(V) was measured. Note that ΔV□(V) in the table is a value calculated using the following formula V=V, p(V) V+soo*r (V).

Table 1 As is clear from Table 1, the use of biphenyl derivatives in combination 1.
, fs The electrophotographic photoreceptors of Examples 1 to 6 all had higher sensitivity and lower residual potential in repeatability than the electrophotographic photoreceptor of Comparative Example 1 that did not contain a biphenyl derivative. there were.

Furthermore, the electrophotographic photoreceptors of Comparative Examples 2 and 3 using 2,3-dichloro-1,4-naphthoquinone as a sensitizer had extremely high residual potentials in terms of repetition characteristics.

(Effects of the Invention) The electrophotographic photoreceptor of the present invention is constructed as described above, has a high sensitizing effect, and is excellent in preventing increases in residual potential when image processing is repeated.

Claims (2)

[Claims] (1) A biphenyl derivative represented by the following formula [I] ▲Mathematical formula, chemical formula, table, etc. is included along with the charge transport material▼[I] (In the formula, R represents an aralkyl group) Contains a biphenyl derivative in the binder resin An electrophotographic photoreceptor characterized by having a layer. (2) The electrophotographic photoreceptor according to claim 1, wherein the biphenyl compound is parabenzylbiphenyl.