JPS62250458A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the titled body having less tendency for generating crystallization and inhomogeneity in an electrostatic charge transfer layer of the titled body by incorporating a polycarbonate resin contg. bisphenol A and a specific dioxy compd. as a diol component, and a specific benzidine compd. in the electrostatic charge transfer layer of the titled body. CONSTITUTION:The electrostatic charge transfer layer contains the polycarbonate resin contg. bisphenol A shown by formula I and the dioxy compd. shown by formula II, as the diol component, and the benzidine compd. shown by formula III, in the electrostatic charge transfer layer. The compounding ratio of bisphenol A shown by formula I and the dioxy compd. shown by formula II in the polycarbonate resin is effectively a range of (1:19)-(19:1), preferably, (3:17)-(1:1). The polycarbonate resin has preferably a mol.wt. of 50,000-110,000. The compounding ratio of the benzidine compd. shown by formula III contd. in the electrostatic charge transfer layer is preferably 25-75wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic organic photoreceptor.

Conventional technology Recently, the mainstream of photoreceptors for electrophotography is a multilayer organic photoreceptor for electrophotography, which has two layers: a charge generation layer that generates charges when exposed to light, and a charge transport layer that transports charges. .

Generally, a laminated organic photoreceptor is obtained by forming a charge generation layer and a charge transport layer by a coating process on a film such as PET (polyethylene terephthalate) on which a conductive layer is formed by a method such as vapor deposition. A flexible photoreceptor can be produced. Since such a photoreceptor can be processed into a belt shape and used repeatedly in an electrophotographic copying machine, it has the advantage that the degree of freedom in the shape of the hardware of the copying machine can be expanded.

In this layered organic photoreceptor, bisphenol A polycarbonate resin is widely used as a binder polymer for the charge transport layer. Among ordinary general-purpose resins, bisphenol A polycarbonate resin has relatively good phase resistance with a charge transport agent, so it has good electrical properties when produced as a photoreceptor, and also has relatively good mechanical properties. It is characterized by high strength.

Problems to be Solved by the Invention However, when the charge transport layer is formed using bisphenol A polycarbonate resin as the binder polymer for the charge transport layer of a multilayer organic photoreceptor for electrophotography, Crystals form and reduce the light attenuation function of the photoreceptor, resulting in defects in image quality such as black spots on copies, and cracks that occur when the photoreceptor is rotated for a long time in the form of a belt. This may appear as a cracked pattern on the copy. Furthermore, if the amount of the charge transport agent increases, it will not be completely compatible and will form an inhomogeneous layer, resulting in weaker strength and precipitation of the charge transport agent on the surface of the photoreceptor over time. There are problems, and a satisfactory photoreceptor has not yet been obtained.

An object of the present invention is to provide an electrophotographic photoreceptor that does not cause crystallization or non-uniformity in the charge transport layer and does not cause cracking when formed into a belt.

Means and Effects for Solving the Problems The present invention provides an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer, in which the charge transport layer contains bisphenol A represented by the following structural formula (I) and the following: A dioxy compound represented by structural formula (II) (wherein X and X' each represent a hydrogen atom, a halogen atom, or a methyl group, and R represents a hydrogen atom, a halogen atom, or water M
group, carboxyl group, acetyl group, or alkyl group having 1 to 4 carbon atoms. ) as a diol component and the following structural formula (III) (wherein R1 and R2 each represent an alkyl group,
R3 to R6 each represent hydrogen, an alkyl group, an alkoxy group, a halogen atom or a substituted amino group. ) These problems have been solved by incorporating the benzidine compound shown in the formula below.

The polycarbonate according to the present invention can be produced using a compound represented by the structural formula (I>) and a compound represented by the structural formula (II>) using a known synthesis method that is used to synthesize general polycarbonates, such as the following. It is synthesized by appropriately applying synthetic methods.

(a) Reaction using phosgene (b) Reaction using bischloroformate of the compound represented by structural formula (I) and structural formula (n) (c) Reaction using bischloroformate of the compound represented by structural formula (I) and structural formula (II) Reaction using a monochloroformate of a compound represented by (d) Reaction using a carbonic acid diester (e) Reaction using a hiscarbonate of a compound represented by structural formula (I> and structural formula (II>) (f) Structural formula (I>) and Reaction using a monocarbonate of the compound represented by Structural Formula (II). Specific examples of the dioxy compound represented by Structural Formula (n) include those having the structure shown below.

H3 0cH3 (:!OOH 0H In the present invention, the compound represented by (I) is most preferably used, but any compound represented by structural formula (II>) is applicable.

Moreover, the polycarbonate resin used in the present invention is
The diol component may contain other bisphenol compounds in addition to the compounds represented by the structural formulas (I) and (II).

Examples of the benzidine compound represented by the structural formula (III) used in the present invention include the following.

(In the formula, Me represents a methyl group, Et represents an ethyl group, Pr represents a propyl group, and Bu represents a butyl group.) In the present invention, the compound shown in All benzidine compounds represented by formula (III) are applicable.

In the present invention, the ratio of the bisphenol 8 represented by the structural formula (I) and the dioxy compound represented by the structural formula (II) in the polycarbonate resin is 1:19 to 19:1.
However, if the ratio of the Sufuninol A component is too high, the crystallinity of the polycarbonate resin will increase, while if the ratio of the dioxy compound is too high, the polycarbonate resin will become brittle. As such, a preferred range is 1:9 to 4:1, and an even more preferred range is 3:17 to 1:1.

In addition, it is appropriate for the polycarbonate resin in the present invention to have a molecular weight of 10,000 to 150,000, but if the molecular weight is too small, the strength of the resin will decrease, and if the molecular weight is too large, the viscosity will increase during production. Since stirring becomes difficult, a molecular weight in the range of 50,000 to 110,000 is preferable.

In the present invention, the structural formula (III
) The ratio of benzidine compounds is 25 to 75w.
Preferably, it is t%. If the ratio of benzidine-based compounds is less than 25 wt%, problems such as desensitization and residual potential may occur in the charge transport function, resulting in the inability to obtain density on copies or overlapping of white background areas. ,7
When the amount is 5 wt% or more, the benzidine compound has poor film properties, resulting in a weak photoreceptor.

The thickness of the charge transport layer is usually in the range of 3 μTrL to 50 μm, but from the viewpoint of charge retention and manufacturability, it is less than 5 μm.
It is more desirable that the thickness be in the range of TrL to 30 μm.

Additionally, if necessary, additives are added to the charge transport layer to impart various functions to the photoreceptor, such as a plasticizer to increase flexibility and a release agent to prevent toner filming. can be added.

When using the polycarbonate resin of the present invention, the solution viscosity is higher than when using a polycarbonate resin in which the polyol component consists only of bisphenol, so it may be necessary to lower the solid content of the coating solution. . In such cases, it is desirable to add a leveling agent or the like to prevent deterioration of the surface properties of the coated surface.

The electrophotographic photoreceptor of the present invention has at least a charge generation layer and a charge transport layer on the conductive layer. The generation layers may be laminated. Further, a conductive or insulating protective layer may be formed as a surface layer if necessary. Furthermore, an adhesive layer that improves the adhesion between each layer, or an intermediate layer (blocking layer) that serves to block charges may be formed.

The conductive substrate material used for this photoreceptor is a metal plate such as aluminum, brass, copper, nickel, or steel, or a conductive material such as aluminum, nickel, chromium, palladium, graphite, etc. on a metal sheet or plastic sheet. It is possible to use a material coated with a conductive substance by vapor deposition, sputtering, coating, etc., and subjected to conductive treatment, or a material made of glass, plastic plate, cloth, paper, etc. and conductive treated.

Charge generating materials in the charge generating layer include amorphous selenium, trigonal selenium, zinc oxide, titanium oxide, selenium-tellurium alloy, AS2Se3, metal- or metal-free phthalocyanine, squareium pigment, anthracene, pyrene, perylene, pyrylium. salt, cyanine, thiapyrylium salt,
Polyvinylcarbazole or the like can be used.

The charge generation layer is formed by vapor deposition or coating together with a binder polymer using these charge generation materials.

Binder polymers in the charge generation layer include polystyrene, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl acetal, alkyd resin, acrylic resin, polyacrylonitrile, polycarbonate, polyamide, polyketone, polyacrylamide, and butyral. Known resins such as thermoplastic resins such as polyester, thermosetting resins such as polyurethane, Epoquin resin, and phenol resins are used.

Note that the polycarbonate resin of the present invention may be used as the binder polymer of the charge generation layer.

Solvents that can be used in the coating liquid I for forming the charge generation layer and the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene;
Ketones such as acetone, methyl ethyl ketone and cyclohexanone, alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate and methyl cellosolve, carbon tetrachloride, carbon tetrabromide, chloroform,
Examples include halogenated hydrocarbons such as dichloromethane, ethers such as tetrahydrofuran and dioxane, dimethylformamide, dimethylsulfoxide, etc., and mixed solvents thereof.

The respective layers are applied using an applicator, a spray coater, a percoater, a dip coater, a doctor blade, or the like.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples. "
"Parts" means "parts by weight" unless otherwise specified.

Example 1 Polycarbonate (molecular weight 68
,000> was synthesized.

2.5 parts of the benzidine compound of Exemplary Compound (1) and 3.5 parts of the above polycarbonate were placed on an electrically conductive transparent support (indium oxide vapor deposited on the surface of a polyethylene terephthalate film of 100 μm thickness.Surface resistance: 103Ω).
A coating solution prepared by dissolving 50 parts of dichloromethane in 60 parts of dichloromethane was applied using a wire round rod, and dried to a thickness of 8 μm.
A charge transport layer was formed.

On the other hand, 2 parts of Squarium pigment represented by the following structural formula and 2 parts of polyester resin (Toyo Bobo Vylon 200) were added to a mixed solution of 130 parts of dichloromethane and 130 parts of 1°1.2-trichloroethane. was ground in a ball mill and prepared into a liquid.

The resulting coating liquid is applied over the charge transport layer using a wire laner.
Apply using Syntrorad and dry to a thickness of approximately 1 μm.
A charge generation layer was formed.

In this case, the charge transport layer was not crystallized during the application of the charge generation layer. A belt-shaped photoreceptor was made by welding this photoreceptor, and the belt was continuously rotated while making copies using a belt module using a roll with a 2-inch radius. No cracks were found on the photoreceptor even when examined using a magnifying glass. Furthermore, the image quality during this period was also good.

Example 2 A photoreceptor was produced in the same manner as in Example 1, except that polycarbonate was synthesized by changing the ratio of the dioxy compound of Compound Example (I) to 1 part of bisphenol A to 1 part of bisphenol A. .

In this case as well, the charge transport layer did not crystallize during application of the charge generation layer. Using the same belt module as in Example 1, this photoreceptor was continuously rotated while making copies, and as far as the 20th cycle was examined, cracks on the photoreceptor were found even when a magnifying glass was used. I was not able to admit.

In addition, compared to the case of using bisphenol A polycarbonate resin, the phenomenon of white spots on copies called daylighting, which is thought to be caused by oxidative deterioration of the photoreceptor, is less likely to occur, and the image quality is lower in the range up to 20 cycles mentioned above. It was in good condition.

Example 3 Polyethylene terephthalate 1~ with aluminum vaporized
The same charge generation layer as in Example 1 was coated on the film. On top of this, a thickness of 10% was prepared in the same manner except that 3 parts of the benzidine compound of Exemplified Compound O was used instead of 2.5 parts of the hensidine compound of Exemplified Compound (1) in Example 1.
A charge transport layer with a thickness of μm was formed, and a photoreceptor was formed with a thickness of (q).

In this case, the same evaluation as in Example 1 was performed, and no crystallization problem occurred, and no cracks were observed on the photoreceptor during continuous rotation up to 20 cycles. Furthermore, the whitening phenomenon that is often observed during continuous rotation and is thought to be caused by the precipitation of low-molecular compounds in the charge transport layer did not occur.

Effects of the Invention As described above, the present invention does not cause crystallization or non-uniformity in the charge transport layer, and can prevent the problem of cracks in the belt-shaped photoreceptor. In particular, in the case of a structure in which a charge generation layer is formed as an upper layer on a charge transport layer, crystallization of the charge transport layer by the coating solvent occurs when applying the coating solution for forming the upper layer. There are no microcracks called ``chopsticks'', and the effect is like that of chopsticks.

Claims (1)

[Claims] In an electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer, the charge transport layer has the following structural formula (
There are formulas, chemical formulas, tables, etc. for bisphenol A represented by (I) and the dioxy compound represented by the structural formula (II) below.
There are chemical formulas, tables, etc. ▼ (II) (In the formula, X and X' each represent a hydrogen atom, a halogen atom, or a methyl group, and R represents a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, an acetyl group, or the number of carbon atoms. 1
A polycarbonate resin containing as a diol component (representing an alkyl group of R_2 is an alkyl group R
_3 to R_6 each represent hydrogen, an alkyl group, an alkoxy group, a halogen atom, or a substituted amino group).