JP3333977B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic organic photoreceptor.

[0002]

2. Description of the Related Art Conventionally, in a Carlson method electrophotographic copying machine, after uniformly charging the surface of a photoreceptor, the charge is erased imagewise by exposure to form an electrostatic latent image, and the electrostatic latent image is formed. The latent image is developed with toner, and then the toner is transferred and fixed on paper or the like.

On the other hand, the photoreceptor is subjected to removal of adhered toner, charge removal, and surface cleaning, and is repeatedly used for a long time.

Accordingly, the electrophotographic photoreceptor has not only electrophotographic characteristics such as good charging characteristics and sensitivity and low dark decay, but also printing durability, abrasion resistance and moisture resistance in repeated use. Good physical properties, resistance to ozone generated during corona discharge, resistance to ultraviolet light during exposure, etc. (environmental resistance) are also required.

Conventionally, selenium,
Inorganic photoreceptors containing an inorganic photoconductive substance such as zinc oxide and cadmium sulfide as a main component of a photosensitive layer have been widely used. In recent years, as a photosensitive layer of an electrophotographic photoreceptor, a carrier generating function and a carrier transporting function are shared by different substances, and a substance exhibiting each function is selected from a wide range in view of desired characteristics, and has high sensitivity and high durability. There is a trend to commercialize organic photoreceptors.

Conventionally, such a function-separated type organic photoreceptor is mainly used for negative charging, and a thin carrier generating layer is provided on a support as described in JP-A-60-247647. A configuration is adopted in which a relatively thick carrier transport layer is provided. However, the two-layer structure of the charge generation layer and the charge transport layer has problems such as poor charging characteristics, large dark decay, and poor image quality, and an intermediate layer is often provided between the substrate and the charge generation layer. . As the material of the intermediate layer, casein, polyvinyl alcohol resin, polyvinyl butyral resin, cellulose resin, and the like are well known, but all have a high residual potential or change in electric resistance value due to environmental fluctuations, and the There is a problem that the surface potential changes.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photoreceptor having high sensitivity, little sensitivity deterioration, small change in potential characteristics due to environmental changes, and good image quality.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member having a photosensitive layer in which an intermediate layer, a charge generation layer and a charge transport layer are sequentially laminated on a conductive substrate. Sublimation purification and acid paint represented by the following general formula [I] and / or general formula [II], wherein the charge generation layer contains a polyamide resin of
This is achieved by an electrophotographic photoreceptor containing a perylene pigment which has been subjected to a roasting treatment .

[0009]

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(In the formula, Z is a substituted or unsubstituted organic atomic group forming a heterocyclic ring.) In the present invention, by adding a polyamide resin to the intermediate layer, charging potential, dark decay characteristics, residual potential, An electrophotographic photoreceptor that is excellent in image characteristics, has excellent sensitivity by containing the perylene pigment having a specific crystal type in the charge generation layer, and exhibits stable characteristics with little potential change even when repeatedly used. can get. That is, it is found that an electrophotographic photoreceptor having extremely excellent properties can be obtained by combining an intermediate layer mainly composed of a polyamide resin and a charge generation layer using the perylene pigment having a specific crystal form as a charge generation substance. Was. Further, by performing the sublimation purification and acid paste treatment of the perylene pigment, further, by forming a charge generation layer using a dispersion liquid dispersed in a ketone solvent together with polyvinyl butyral resin, the above-described effect becomes more remarkable. I found it.

[0011]

The structure of the present invention will be described below in detail.

The intermediate layer of the present invention will be described.

The intermediate layer can function not only as a bonding layer between the conductive substrate and the photoconductive layer, but also as a barrier layer for preventing charge injection from the substrate. Therefore, it is necessary that the solvent is not easily affected by the solvent used for coating the upper photosensitive layer.

For the intermediate layer, a copolymer type or modified type alcohol-soluble polyamide resin is used. Examples of the copolymer type polyamide include nylon 6,
Copolymers such as 8, 11, 12, 66, 610, 612, etc., specifically, (1) Daiamide T-170 (manufactured by Daicel-Huls Co., Ltd.) Nylon 12-based copolymer (2) Alamine CM8000 (manufactured by Toray Industries, Inc.) 6/66/610/12 copolymer nylon (3) Ultramid 1c (manufactured by BASF Japan Ltd.)
6/66/610 Copolymer nylon (4) Elbamide 8061 (manufactured by DuPont Japan KK)
6/66/610 copolymer nylon or the like is preferably used.

Examples of the modified polyamides include N-methyl-modified nylon 6, methoxymethyl-modified nylon 6, N-ethyl-modified nylon 8, and ethoxymethyl-modified nylon 8 alkyl-modified polyamide resins. In particular, the above-mentioned methoxymethyl-modified polyamide resin of nylon 6 is preferable, and specifically, (1) Luctamide 5003 (manufactured by Dainippon Chemical Industries, Ltd.) (2) Luctamide 5216 (manufactured by Dainippon Chemical Industries, Ltd.) (3) Toresin F30 (manufactured by Teikoku Sangyo Chemical Co., Ltd.) (4) Toresin EF-20T (manufactured by Teikoku Sangyo Chemical Co., Ltd.) or the like is used.

Examples of the solvent used include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, and isobutyl alcohol.

The thickness of the intermediate layer is arbitrarily set.
m or less, particularly preferably 1 μm or less.

The formation of the intermediate layer can be carried out by applying by an appropriate method such as spray coating, dip coating, knife coating, roll coating and the like.

The effect of charging by the formation of the intermediate layer is particularly remarkable when the conductive substrate is a metal such as Al or Ni.

Next, the charge generation layer will be described.

In the present invention, by including the perylene pigment according to the present invention in the charge generating layer, an electrophotographic photosensitive member having high sensitivity and excellent repetitive potential stability can be obtained. The charge generation layer is formed by, for example, using a ball mill, a sand grinder, or the like to make the charge generation material into fine particles (preferably 5 μm or less, more preferably 1 μm or less) in a dispersion medium, and if necessary, a binder resin and / or a charge. It can be formed by providing an intermediate layer on a conductive support using a dispersion liquid in which a transport substance is added and mixed and dispersed, and coating the intermediate layer thereon.

As another method, it can be formed by providing an intermediate layer on a conductive support and depositing a pigment on the intermediate layer in a vacuum. However, as a result of investigations by the present inventors, when a charge generation layer is formed by a vacuum deposition method, defects such as pinholes and abnormal deposits often occur in the charge generation layer film. It was found that the image quality was better when the generation layer film was formed.

Hereinafter, the charge generation material of the present invention will be described in detail.

The charge generating material used in the photoreceptor of the present invention has a Bragg angle (2θ ± 0.2 °) of 2θ = 6.3 °, 12.4 °, 25.3 °, X-ray diffraction measurement with respect to Cu-Kα ray.
It has a peak at 27.1 °, the peak intensity at 12.4 ° is the maximum, the half width of the peak is 0.65 ° or more, and 11.5 °
A perylene pigment having a specific crystal form that does not show a clear peak and having a structure defined by the general formula [I] and / or the general formula [II].

The above general formula [I] and / or general formula [II]
Preferred examples of Z in the structural formula defined by include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyridine ring, a pyrimidine ring, a pyrazole ring, and an anthraquinone ring. Preferably, there is. The aromatic ring represented by Z may be substituted. Examples of the substituent include an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an ashile group, an acyloxy group, an amino group, a carbamoyl group, and a halogen atom. , A nitro group, a cyano group and the like.

Further, it is preferable that the perylene pigment according to the present invention has been subjected to a sublimation purification treatment and an acid paste treatment.

The following are specific examples of the perylene pigment according to the present invention, but the present invention is not limited thereto.

[0028]

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These exemplified compounds are described in, for example,
It is synthesized by the methods described in JP-A-49-128734 and JP-A-59-59686.

Generally, in order to obtain highly sensitive photoreceptor characteristics, first, it is necessary to obtain a fine and uniform coating film of a charge generating substance. That is, the first important thing in the dispersion atomization step is to atomize the charge generating substance. However, as a result of investigations by the present inventors, the perylene pigment of the general formula [I] of the present invention has a crystallization effect due to a strong shearing force applied for particle pulverization, depending on the method of pulverization, apart from the sensitizing effect by pulverization. This may cause physical damage to the inside or the surface, resulting in a desensitizing effect, and as a result, the sensitivity characteristic may rather show a remarkable tendency to decrease. Therefore, it is preferable that the atomization of the pigment proceeds with as little shearing force as possible. In the present invention,
It is preferable to perform a pigment paste treatment and use a pigment having a small particle size and a uniform size.

The solvent or dispersion medium used for forming the charge generation layer of the present invention includes n-butylamine, diethylamine, ethylenediamine, isopropanolamine,
Triethanolamine, triethylenediamine, N, N-dimethylformamide, acetone, methyl ethyl ketone,
Methyl isopropyl ketone, cyclohexanone, benzene, toluene, xylene, chloroform, dichloromethane, 1,2-dichloroethane, 1,2-dichloropropane, 1,1,
Examples thereof include 2-trichloroethane, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, and methyl cellosolve. The present invention is not limited to these, but when a ketone-based solvent is used, sensitivity, potential change upon repeated use, and the like are further improved. These solvents can be used alone or as a mixture of two or more solvents.

The binder resin used for the charge generation layer includes polyamide, polyurethane, polyester, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral,
Polyvinyl formal, polystyrene and the like are used.
The present invention is not limited to these, but when a polyvinyl butyral resin is used, sensitivity, potential change upon repeated use, and the like are further excellent. These binder resins are
They can be used alone or as a mixture of two or more.

In the charge generation layer formed as described above, the weight ratio of the charge generation substance to the binder is preferably from 100: 0 to 1: 100.

If the content ratio of the charge generating substance is lower than this, the photosensitivity is low and the residual potential is increased, and if it is higher than this, the dark decay is increased and the receiving potential is lowered.

When the charge generating layer contains a charge transporting material, the ratio of the charge generating material to the charge transporting material is preferably from 10:10 to 10: 1000 by weight, and particularly preferably from 10:10 to 10: 1000. : 0 to 10: 100.

The thickness of the formed charge generation layer is preferably 0.01 to 10 μm.

As a coating method, an ordinary method such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, or a bead coating method can be used.

The charge transport layer in the present invention will be described.

The charge transport layer is formed from a charge generating substance and a binder resin.

The charge transporting material used in the present invention is not particularly limited. For example, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazo derivatives Lysine derivatives, styryl compounds, hydrazone compounds, benzidine compounds, pyrazoline derivatives, stilbene compounds, amine derivatives, oxazolone derivatives, benzothiazole derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives,
Phenazine derivative, aminostilbene derivative, poly-N-
Vinyl carbazole, poly-1-vinylpyrene, poly-9-vinylanthracene and the like can be mentioned.

As the binder resin used for the charge transport layer, a wide range of insulating resins can be appropriately selected and used. Preferred binder resins include polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polycarbonate resin, polyvinyl acetate resin, styrene-butadiene copolymer, and vinylidene chloride-acrylonitrile copolymer. , Vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin,
Insulating resins such as phenol-formaldehyde resin, poly-N-vinylcarbazole, and polysilane can be used, but are not limited thereto. These binder resins can be used alone or in combination of two or more.

Examples of the solvent used for forming the charge transport layer include aromatic hydrocarbons such as benzene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and methylene chloride, chloroform and ethylene chloride. Conventional organic solvents such as halogenated aliphatic hydrocarbons, cyclic or linear ethers such as tetrahydrofuran and ethyl ether can be used alone or in combination of two or more.

The compounding ratio of the binder resin to the charge transport material is 1:10
~ 500, more preferably 1: 20-150. The thickness of the charge transport layer is set to 1 to 100 μm, preferably 5 to 50 μm.

As a coating method, the same method as that for the charge generation layer can be used.

Further, various additives can be contained for the purpose of improving the function of the charge transport layer.

[0046]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the embodiments of the present invention are not limited thereto.

Synthesis Example 39.2 g of perylene-3,4,9,10-tetracarboxylic dianhydride, 32.4 g of o-phenylenediamine,
800 ml of α-chloronaphthalene was mixed and reacted at 260 ° C. for 6 hours. After cooling, the precipitated crystals were collected by filtration and washed repeatedly with methanol. By heating and drying, Exemplified Compound A-1 was synthesized.

(Sublimation Example) The exemplified compound A-1 obtained in the above synthesis example was subjected to sublimation purification under a heating condition of 500 ° C. under a pressure of 5 × 10 ^{−4 to} 5 × 10 ⁻³ torr. Volatile impurities were removed using a shutter. The obtained purified crystals were again subjected to the same sublimation treatment to further purify the crystals. A product that has been subjected to two sublimation operations in this manner is referred to as a sublimated product (SUB product) of Exemplified Compound A-1.

(Example of Acid Paste Treatment) A solution prepared by dissolving 20 g of the sublimation product of Exemplified Compound A-1 in 600 ml of concentrated sulfuric acid was filtered through a glass filter, and then dropped into 1200 ml of pure water to precipitate. This was collected by filtration, washed sufficiently with pure water, and dried. The compound thus obtained was used as Exemplified Compound A-1
Acid paste processed product (AP product).

(Preparation of Photoconductor 1) 30 g of a copolymerized polyamide resin CM8000 (Toray Industries, Inc.) was charged and dissolved in a mixed solvent of 900 ml of methanol and 100 ml of 1-butanol. Using this liquid, dip coating was performed on an aluminum drum having an outer diameter of 80 mm and a length of 355.5 mm to form an intermediate layer having a thickness of 0.5 μm. Subsequently, 6 g of polyvinyl butyral resin SREC BLS (Sekisui Chemical Co., Ltd.) was added to methyl ethyl ketone (Kanto Chemical
Co., Ltd.) dissolved in 1000 ml, further mixed with 28 g of the AP compound of Exemplified Compound A-1 obtained by the method described above, and dispersed with 2000 g of glass beads having a diameter of 1 mm using a sand mill for 15 hours. 1 was obtained. Using this solution, a charge generation layer having a thickness of 0.5 μm was formed on the intermediate layer by dip coating.

At this time, the obtained dispersion was applied a plurality of times on a glass plate and dried to form a dry solid film having a thickness of about 200 μm, and X-ray diffraction using Cu-Kα ray was performed. When the spectrum was measured, the Bragg angle (2θ ±
0.2 °) has 2θ = 6.3 °, 12.4 °, 25.3 °, 27.1 °, the peak intensity at 12.4 ° is the maximum, the half width of the peak is 0.86 °, and a clear peak at 11.5 ° Was not found.

Thereafter, 200 g of the following compound T and polymer B 2
00 g was dissolved in 1000 ml of dichloromethane (Kanto Chemical Co., Ltd.). Using this liquid, a charge transport layer having a thickness of 20 μm was formed on the charge generation layer by dip coating.

Finally, the resultant was dried by heating at 100 ° C. for 1 hour to prepare a photoreceptor 1 in which an intermediate layer, a charge generation layer and a charge transport layer were sequentially laminated. The X-ray diffraction spectrum is shown in FIG.

[0054]

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(Preparation of Photoreceptor 2) Dispersion 2 obtained by dispersing for 20 hours, using 1,2-dichloroethane in place of the solvent methyl ethyl ketone of the dispersion 1 and using a dispersion sand mill with a glass bead amount of 2500 g. To form a charge generation layer, and as shown in Table 2, a modified polyamide resin lucamide 50 instead of the polyamide resin CM-8000 of the intermediate layer.
03 (Dai Nippon Ink Chemical Industry Co., Ltd.)
In the same manner as in the above, a photoreceptor 2 was produced.

When the X-ray diffraction spectrum of the dispersion 2 was measured, as shown in Table 1, the peak intensity at 12.4 ° was the maximum, the half width of the peak was 0.94, and a clear peak was observed at 11.5 °. It turned out not to show.

(Preparation of Photoreceptor 3) Tetrahydrofuran was used instead of the solvent methyl ethyl ketone of the dispersion 1, and the amount of glass beads in a sand mill for dispersion was 1500.
g, and a dispersion 3 obtained by dispersion for 10 hours was used to form a photoconductor 3 in the same manner as the photoconductor 1 except that a charge generation layer was formed. When the X-ray diffraction spectrum of the dispersion 3 was measured, it was found that the peak intensity at 12.4 ° was the maximum, the half width of the peak was 0.68 °, and no clear peak was at 11.5 °.

(Preparation of Photoreceptor 4) As shown in Table 2, a polyvinyl butyral resin SREC BH-3 (manufactured by Sekisui Chemical Co., Ltd.) was used in place of the resin CM-8000 for the intermediate layer of the photoreceptor 1. Photoconductor 4 in the same manner as Photoconductor 1 (for Comparative Example 1)
Was prepared.

(Preparation of Photoconductor 5) Photoconductor 1 was prepared in the same manner as above except that dispersion 4 containing perylene pigment G2 having the following structure was used instead of AP product of Exemplified Compound A-1 contained in dispersion 1.
In the same manner as in the above, Photoconductor 5 (for Comparative Example 2) was produced.

[0060]

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(Preparation of Photoconductor 6) As shown in Table 2, the photoconductor 6 was manufactured in the same manner as the photoconductor 1 except that the intermediate layer of the photoconductor 1 was removed.
(For Comparative Example 3) was produced.

(Preparation of Photoreceptor 7) The same as the photoreceptor 1 except that the dispersion liquid 5 obtained by performing dispersion for 5 hours using ultrasonic dispersion was used instead of the sand mill as the dispersing means of the dispersion liquid 1 described above. Thus, a photoreceptor 7 (for Comparative Example 4) was produced.

When the X-ray diffraction spectrum of the dispersion 5 was measured, as shown in Table 1, the peak intensity at 12.4 ° was the maximum, and the half-width of the peak was 0.60 ° and 11.5 °.
It turned out to show a clear peak.

(Preparation of Photoconductor 8) In place of the AP of Exemplified Compound A-1 contained in Dispersion 1, Exemplified Compound A-
Photoconductor 8 (for Comparative Example 5) was prepared in the same manner as photoconductor 1, except that dispersion 6 containing sublimation product (SUB) was used.

When the X-ray diffraction spectrum of the dispersion 6 was measured, as shown in Table 1, it did not have the maximum peak intensity at 12.4 °, had the maximum peak intensity at 27.1 °, and The half-width of the peak was 0.68 °, and it was found that there was no clear peak at 11.5 °. The X-ray diffraction spectrum is shown in FIG.

(Preparation of Photoreceptor 9) Exemplified compound A-1 was used in place of the AP product of Exemplified compound A-1 contained in the dispersion.
Sublimated product (SUB), and toluene-isopropyl alcohol (1:
Photoconductor 9 (for Comparative Example 6) was prepared in the same manner as photoconductor 1, except that dispersion 7 containing 1) was used.

When the X-ray diffraction spectrum of the dispersion 7 was measured, as shown in Table 1, the dispersion had the maximum peak intensity at 27.1 °, the half value width of the peak at 12.4 ° was 0.52 °, and 11.5 °. It was found to have a clear peak at °.

[0068]

[Table 1]

[0069]

[Table 2]

(2) Evaluation Photoconductors 1 to 9 were mounted on U-BIX 4155 manufactured by Konica Corporation, and
Image evaluation was performed on 100,000 sheets in an environment of 60 ° C. and a relative humidity of 60%. 33 ° C, relative humidity 80% and 10 ° C, relative humidity
The surface potential of the photoreceptor was measured in a 20% environment, and the fluctuation range of the surface potential due to the environment was evaluated.

[0071]

[Table 3]

In the table, _Vb and _VW represent the reflection density of 1.
3, represents the photoconductor surface potential corresponding to the original of 0.00.

[0073]

According to the present invention, it is possible to provide a photoreceptor with high image quality, high sensitivity, little sensitivity deterioration, small change in potential characteristics due to environmental changes, and good image quality.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum diagram in the present invention.

FIG. 2 is an X-ray diffraction spectrum diagram outside the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-281769 (JP, A) JP-A-5-204179 (JP, A) JP-A-61-83542 (JP, A) JP-A-63-63 204280 (JP, A) JP-A-5-249719 (JP, A) JP-A-4-186364 (JP, A) JP-A-4-62560 (JP, A) JP-A-4-264448 (JP, A) JP-A-4-204850 (JP, A) JP-A-5-119496 (JP, A) JP-A-5-80564 (JP, A) JP-A-4-276761 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 5/00

Claims (2)

(57) [Claims] 1. An intermediate layer, a charge generation layer,
In an electrophotographic photoreceptor in which a charge transport layer is sequentially laminated, the intermediate layer contains an alcohol-soluble polyamide resin as a main component, and the charge generation layer has a Bragg angle (2θ) in X-ray diffraction measurement with respect to Cu-Kα radiation. ± 0.2 °)
θ = 6.3 °, 12.4 °, 25.3 °, with peaks at 27.1 ° 12.
The peak intensity at 4 ° is the maximum and the half width of the peak is 0.6
Represented by the following general formula [I] and / or general formula [II], which is not less than 5 ° and does not show a clear peak at 11.5 ° ,
An electrophotographic photoreceptor formed by using a dispersion obtained by sublimation purification and acid paste treatment, wherein a perylene pigment is dispersed in an organic solvent together with a polymer binder resin. Embedded image (In the formula, Z is a substituted or unsubstituted organic atomic group forming a heterocyclic ring.) 2. The method according to claim 1, wherein the organic solvent is a ketone solvent.
The polymer binder resin is a polyvinyl butyral resin.
The electrophotographic photosensitive member according to claim 1.