JPH04136949A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To offer an electrophotographic sensitive body superior in responsiveness and high sensitivity and superior in repetition characteristics to be used for copying machines and printers by using a novel organic material as an electric charge transfer material for a photosensitive layer. CONSTITUTION:The photosensitive layer formed on a conductive substrate can be enhanced in sensitivity and repetition characteristics both in the case of positive and negative charging by incorporating as the charge transfer material one of the compounds represented by general formulae I and II. As the charge generating material, a proper one can be selected in accordance with a kind of light source, and the photosensitive body usable for semiconductor laser printers can be obtained by using one selected from phthalocyanine compounds, squarylium compounds, and some kind of bisazo pigments, etc. Durability can be enhanced by forming a coating layer on the surface as necessary.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor, and more specifically, an electrophotographic photoreceptor containing a novel compound in a photosensitive layer formed on a conductive substrate. Regarding.

[Conventional technology]

Conventionally, photosensitive materials for electrophotographic photoreceptors (hereinafter also referred to as photoreceptors) include inorganic photoconductive substances such as selenium or selenium alloys, or inorganic photoconductive substances such as zinc oxide or cadmium sulfide in a resin binder. Dispersed, Po I
J Organic photoconductive substances such as N-vinylcarbazole or polyvinylanthracene, phthalocyanine compounds, or bisazo compounds dispersed in a resin binder or vacuum-deposited are used. There is.

In addition, a photoreceptor must have the function of retaining surface charge in the dark, the function of receiving light and generating charge, and the function of receiving light and transporting charge, all of which can be achieved in one layer. A so-called single-layer photoreceptor with the following functions is laminated with functionally separated layers: a layer that mainly contributes to charge generation, and a layer that contributes to surface charge retention in the dark and charge transport during light reception. There is a so-called laminated photoreceptor. For example, the Carlson method is applied to image formation by electrophotography using these photoreceptors. Image formation in this method involves charging the photoconductor in a dark place by corona discharge, forming an electrostatic latent image such as text or pictures on the original on the surface of the charged photoconductor, and forming an electrostatic latent image on the surface of the charged photoconductor. After the toner image has been transferred, the photoreceptor is subjected to static electricity removal, removal of residual toner, photostatic static removal, etc. before being reused. be done.

In recent years, many applications of photoconductive organic compounds with excellent charge transport ability to photoreceptors have been proposed due to their advantages such as flexibility, thermal stability, and film-forming properties.

For example, as an oxadiazole compound, US Pat.
189447, pyrazoline compounds in Japanese Patent Publication No. 59-2023, and hydrazone compounds in Japanese Patent Publication No. 55-42380 and Japanese Patent Application Laid-open No. 57101.
No. 844, as for triarylamine, JP-A-58
Various charge transport materials are known from Japanese Patent Application Laid-Open No. 58-198043 as a stilbene compound.

[Problem to be solved by the invention]

As mentioned above, organic materials have many advantages that inorganic materials do not have, but at the same time, there is currently no material that fully satisfies all the characteristics required of electrophotographic photoreceptors. There were problems with photosensitivity and characteristics during repeated and continuous use.

The present invention has been made in view of the above-mentioned points, and by using a new organic material that has never been used as a charge transport material in the photosensitive layer, it has excellent responsiveness, high sensitivity, and repeatability. The purpose of the present invention is to provide an excellent electrophotographic photoreceptor for copying machines and printers.

[Failure to solve the problem]

According to the present invention, the above object is achieved by having a photosensitive layer containing at least one compound represented by the following general formula (I) or (formula).

(In the formula, R1 and r<. each represent a hydrogen atom, an alkyl group, or an aryl group, R,, R, ・ R5 and R6 each represent an alkyl group, a substituted or unsubstituted aryl group, or a heterocyclic group, and n represents an integer from 1 to 3.) (. Rs, Rho, R
and R12 each represent an alkyl group, a substituted or unsubstituted aryl group, or an aralkyl group, R13 and R14 each represent a hydrogen atom or an alkyl group, and Ar
represents an aryl group or a heterocyclic group, and m represents an integer of 1 to 3. ) The compound represented by the general formula (I) or (It) is
The present invention is the first to provide a compound that exhibits excellent properties as a charge transport material.

[Function] There is no known example in which a compound represented by the above general formula (I) or (II) is used in a photosensitive layer. In order to achieve the above object, the present inventors conducted a number of experiments on various organic materials and found that although their technical clarification has not yet been fully elucidated, It has been discovered that the use of a specific compound represented by formula (I) or (former) as a charge transport material is extremely effective in improving electrophotographic properties, and a photoreceptor with high sensitivity and excellent repeatability has been developed. I was able to obtain this.

〔Example〕

The compound represented by formula (I) or (II) is
For example, - aldehydes represented by the formula (III) or (TV) and - Br represented by the formula (V) or (Vl) - Specific examples of the compounds represented by the formula (I) or (I1) Examples are as follows.

the law of nature,? (Wittig) reagent by the well-known Wittig reaction.

Compound Teeth 11-7 Positive I=-8 h11-9 1h11-11 The photoreceptor of the present invention contains the above-mentioned compounds in the photosensitive layer. It can be used as shown in FIG. 2 or 3.

1 to 3 are conceptual cross-sectional views of the photoreceptor of the present invention.
20, 21 and 22 are a conductive substrate, 20, 21 and 22 are photosensitive layers, 3 is a charge generating material, 4 is a charge generating layer, 5 is a charge transporting material, 6 is a charge transporting layer, and 7 is a coating layer.

FIG. 1 shows a photosensitive layer 20 (commonly referred to as a single-layer photoreceptor) in which a charge-generating substance 3 and a charge-transporting substance 5 are dispersed in a resin binder (binder) is provided on a conductive substrate 1. It is something that

FIG. 2 shows a charge generation layer 4 mainly composed of a charge generation substance 3 on a conductive substrate 1, and a compound (I) as a charge transport substance 5.
A photosensitive layer 21 consisting of a laminate with a charge transport layer 6 containing
The structure is usually referred to as a laminated photoreceptor). In some cases it is possible to provide seven covering layers.

FIG. 3 shows an inverse layer configuration to that of FIG.

In this case, it is common to further provide a coating layer 7 to protect the charge generation layer 4.

The reason for the two types of layer configurations shown in Figures 2 and 3 is that even if the layer configuration shown in Figure 2, which is normally used in a negative charging system, is used in a positive charging system, there is no compatible charge transport material. This is because it has not been found yet, and therefore, at the current stage, it is necessary to have the layer structure shown in FIG. 3 as a positive charging type photoreceptor.

The photoreceptor shown in FIG. 1 can be prepared by dispersing a charge generating material in a solution containing a charge transporting material and a resin binder, and applying this dispersion onto a conductive substrate.

The photoreceptor shown in Figure 2 is produced by vacuum-depositing a charge-generating substance on a conductive substrate, or by coating and drying a dispersion obtained by dispersing particles of a charge-generating substance in a solvent or resin binder, and then It can be created by applying a solution containing a charge transport substance and a resin binder to the surface of the substrate and drying the solution.

The photoreceptor shown in Figure 3 is produced by coating a conductive substrate with a solution containing a charge transporting substance and a resin binder and drying it, and then vacuum-depositing a charge generating substance thereon, or by depositing charge generating substance particles in a solvent or a solvent. It can be created by applying a dispersion obtained by dispersing it in a resin binder, drying it, and further forming a coating layer.

The conductive substrate 1 serves as an electrode for the photoreceptor and at the same time serves as a support for the other layers, and may be cylindrical, plate-shaped, or film-shaped, and may be made of aluminum, stainless steel, nickel, etc. It may also be made of metal, glass, resin, or the like, which has been subjected to conductive treatment.

The charge generation layer 4 is formed by applying a material in which particles of the charge generation substance 3 are dispersed in a resin binder as described above, or by a method such as vacuum deposition, and generates charges by receiving light. . In addition, the charge transport layer 6 and the coating layer 7 for the generated charges at the same time have a high charge generation efficiency.
It is important to have good injection properties even in low electric fields with little dependence on electric fields. As the charge generating substance, phthalocyanine compounds such as metal-free phthalocyanine and chikunylphthalocyanine, various azos, quinones, in silico pigments, cyanine, and squarylium are used.

Dyes such as azulenium and pyrylium compounds, selenium or selenium compounds, and the like are used, and suitable substances can be selected depending on the light wavelength range of the exposure light source used for image formation. Since the charge generation layer only needs to have a charge generation function, its thickness is determined by the light absorption coefficient of the charge generation substance and is generally 5 μm or less, preferably 1 μm or less. The charge generation layer is mainly composed of a charge generation substance, and a charge transport substance or the like may be added thereto.

As the resin binder, polycarbonate, polyester, polyamide, polyurethane, vinyl chloride, epoxy, diallyl phthalate resin, silicone resin, polymers and copolymers of methacrylic acid ester, etc. can be used in appropriate combinations.

The charge transport layer 6 is a coating film in which a compound represented by the general formula (I) or (II) as an organic charge transport substance is dispersed in a resin binder, and serves as an insulating layer to retain the charge of the photoreceptor in a dark place. However, when receiving light, it functions to transport charges injected from the charge generation layer. As the resin binder, polycarbonate, polyester, methacrylic acid ester polymers and copolymers, etc. can be used.

The proportion of the compound represented by the general formula (I) or (former) is 30 to 80% by weight, preferably 40 to 60% by weight, based on the resin binder, and examples of the solvent include chloroform, dichloromethane, benzene, toluene, and methyl ethyl ketone. , tetrahydrofuran, etc. can be used.

The coating layer 7 has the function of receiving and retaining the charge of corona discharge in a dark place, and has the ability to transmit the light to which the charge generation layer is sensitive, and transmits the light upon exposure, and the charge generation layer It is necessary to neutralize and eliminate the surface charges by injecting the generated charges. As the coating material, an organic insulating film-forming material such as polyester polyamide can be used. In addition, these organic materials and inorganic polymer resin 5
It is also possible to use a mixture of inorganic materials such as iO7 and materials that reduce electrical resistance such as metals and metal oxides. The coating material is not limited to organic insulating film-forming materials, and inorganic materials such as 5102, as well as metals, metal oxides, etc., can be deposited.

It is also possible to form by a method such as sputtering. As mentioned above, it is desirable that the coating material be as transparent as possible in the wavelength region where the charge generating substance absorbs maximum light.

The thickness of the coating layer itself depends on the composition of the coating layer, but
It can be set arbitrarily within a range that does not cause adverse effects such as an increase in residual potential when used repeatedly and continuously.

Examples of the present invention will be described below.

Example I 50 parts by weight of X-type metal-free phthalocyanine (H2PC) and 100 parts by weight of the compound represented by Compound No. I-1 were mixed with 100 parts by weight of a polyester resin (trade name: Vylon 200, manufactured by Toyobo) and a tetrahydrofuran (THF) solvent. The coating solution was prepared by kneading with a mixer for 3 hours, and the aluminum-deposited polyester film (
A5-PET) using the wire bar method,
A photoreceptor was prepared so that the film thickness after drying was 15 μm.

Example 2 80 parts by weight of the compound represented by Compound No. I-2 and polycarbonate resin (trade name Panlite L122)
5: A coating liquid prepared by dissolving 100 parts by weight (manufactured by Ondai Kasei) in methylene chloride was applied onto an aluminum vapor-deposited polyester film substrate using the wire bar method, and the film thickness after drying was 15 μm.
A charge transport layer was formed to have a thickness of m. On the thus obtained charge transport layer, titanyl phthalocyanine (TiOPc) was pulverized using a ball mill for 150 hours.
50 parts by weight, polyester resin (trade name Byron 200
: 50 parts by weight (manufactured by Toyobo Co., Ltd.) was mixed with THF solvent in a mixer for 3 hours to prepare a coating solution, which was applied by wire bar method to form a charge generation layer so that the film thickness after drying was 1 μm. .

Example 3 A photoreceptor was prepared in the same manner as in Example 2, except that Ti0Pc was replaced with a squarylium compound represented by the following structural formula, and the charge transport material was replaced with the compound No. I-3. Created.

Example 4 In Example 2, instead of Ti0Pc, for example,
A photoreceptor was prepared in the same manner as in Example 2, using chlorodiampurus, which is a bisazo pigment as shown in Publication No. 7-37543, and changing the charge transport substance to the compound shown by Compound No. I-4. .

The electrophotographic properties of the photoreceptor thus obtained were measured using an electrostatic recording paper tester RSP-428J manufactured by Kawaguchi Electric.

The surface potential V, (volt) of the photoreceptor is +6.0kV in the dark.
This is the initial surface potential when corona discharge is performed for 10 seconds to positively charge the surface of the photoreceptor, and the surface potential V is the surface potential when the photoreceptor surface is then held in the dark for 2 seconds with corona discharge stopped.
(volts), and then the illuminance 2 on the photoreceptor surface.
Calculate the time (seconds) it takes for V to be halved after irradiating the lux white light, and find the half-attenuation exposure amount E1/2 (lux seconds)
And so. Further, the surface potential when white light with an illuminance of 2 lux was irradiated for 10 seconds was defined as the residual potential V (volt).

Further, for Examples 1 to 3, since high sensitivity with long wavelength light can be expected, the electrophotographic characteristics when using monochromatic light with a wavelength of 780 nm were also measured at the same time. That is, measurements are made in the same manner up to Vd, and then 1 μW monochromatic light (780 nm) is irradiated instead of white light to obtain a half-attenuation exposure amount (μJ/cnt
) was determined, and the residual potential V, (volt) when the surface of the photoreceptor was irradiated with this light for 10 seconds was measured. The measurement results are shown in Table 1.

Table 1 As seen in Table 1, Examples 1 and 2.34 are comparable in half-attenuation exposure and residual potential, and also exhibit good characteristics in terms of surface potential. Further, Examples 1 to 3 showed high sensitivity even to long wavelength light of 780 nm, and it can be seen that they can be sufficiently used for semiconductor laser printers. Furthermore, for the photoreceptors obtained in Examples 1 to 4, 10
When repeated measurements were performed 0 times, the variation in surface potential before exposure was 70 V or less, and the variation in surface potential after exposure was less than IOV, and excellent results were obtained in terms of repeat stability.

Example 5 On a 500 μm thick aluminum plate, selenium was vacuum-deposited to a thickness of 1.5 μm to form a charge generation layer, and then 100 parts by weight of a compound represented by Compound No. II-1 and a polycarbonate resin were added. (P C220 (++ made by Mitsubishi Gas Chemical) 100 parts by weight was dissolved in methylene chloride, and a coating liquid was applied using the wire bar method, and the film thickness after drying was 20%.
A charge transport layer was formed to have a thickness of μm. When this photoreceptor was corona charged at -6kV for 10 seconds, Vs=
Good results were obtained: 760V, Vr--40V, El/2=2.0 lux·sec.

Example 6 In the same manner as in Example 2, 50 parts by weight of X-type metal-free phthalocyanine and parts by weight of vinyl chloride copolymer (trade name: MR-110 Nippon Zeon) were kneaded with methylene chloride in a mixer for 3 hours to prepare a coating solution. Aluminum support”-
A charge generation layer was formed by coating the film to a thickness of approximately 1 μm. Next, 100 parts by weight of the compound represented by compound No. H2, polycarbonate resin (Panrai) 1-7-1
250) 100 parts by weight of silicone oil and 0.1 parts by weight of silicone oil were mixed with methylene chloride and coated on the charge generation layer to a thickness of about 15 μm to form a charge transport layer.

The photoreceptor thus obtained was corona charged at -5,QkV for 10 seconds in the same manner as in Example 2.
Vs--740V, El, 2 =], 6 Lux seconds Good results were obtained.

Example 7 In Example 6, a bisazo pigment represented by the following structural formula was used instead of the metal-free phthalocyanine, and the charge transport material was replaced with a compound represented by Compound No. II-3, and photosensitization was carried out in the same manner as in Example 6. created a body.

Example 8 Photoreceptors were prepared in the same manner as in Example 4 for each of Compounds No., I-5 to I-18, and ■-/I to ■-12, and the results of measurement using rSP-428J were measured in the second column.
Shown in the table.

+6 in the dark. Corona discharge of QkV was performed for 10 seconds to positively charge the sample, and the half-attenuation exposure amount was expressed as El/2 (lux/sec) when white light with an illuminance of 2 lux was irradiated.

As seen in Table 2, for the photoreceptors using the compounds No. 1-5 to 1-18, 11-4 to 1-12 as charge transport materials, the half-attenuation exposure amount E, 72
was good.

The thus obtained photoreceptor was corona charged at -6, OkV for 10 seconds in the same manner as in Example 4.
Vs-700V, El/2 +1.3 Lux・
Good results were obtained in seconds.

Since the compound represented by formula (I') or (JT) is used as the photoreceptor, it is possible to obtain a photoreceptor with high sensitivity and excellent repeatability even in positive and negative charging. Further, as the charge generating substance, a suitable substance can be selected depending on the type of exposure light source, such as a phthalonanine compound.

By using squarylium compounds and certain bisazo compounds, it is possible to obtain photoreceptors that can be used in semiconductor laser printers. Furthermore, if necessary, it is possible to provide a coating layer on the surface to improve durability.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 are conceptual sectional views showing different embodiments of the photoreceptor of the present invention. 1 conductive substrate, 3 charge generation substance, 4 charge generation layer,
5 Charge transport material, 6 Charge transport layer, 7 [Effects of the invention] According to the present invention, charge transport material 7-1-1,

Claims (1)

[Scope of Claims] 1) A photoreceptor for electrophotography, characterized in that it has a photosensitive layer containing at least one type of compound represented by general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・(
I) (In the formula, R_1 and R_2 each represent a hydrogen atom, an alkyl group, or an aryl group, and R_3, R_4, R_5
and R_6 each represent an alkyl group, a substituted or unsubstituted aryl group, or a heterocyclic group, and n is 1 to
Represents an integer of 3. ) 2) An electrophotographic photoreceptor characterized by having a photosensitive layer containing at least one type of compound represented by the general formula (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・(
II) (In the formula, R_7 and R_8 each represent a hydrogen atom, an alkyl group, or an aryl group, R_9, R_1_0, R
_1_1 and R_1_2 each represent an alkyl group, a substituted or unsubstituted aryl group, or an aralkyl group, R_1_3 and R_1_4 each represent a hydrogen atom or an alkyl group, Ar represents an aryl group or a heterocyclic group, and m is 1 to Represents an integer of 3. 3) The electrophotographic photoreceptor according to claim 1 or 2, wherein the compound is a charge transporting substance.