JPH03157660A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain a separated function type org. sensitive body having high sensitivity and superior durability by forming an electric charge transferring layer composed of two layers having different characteristics, that is, a layer brought into contact with an electric charge generating layer and a layer not brought into contact with the generating layer. CONSTITUTION:When an electric charge transferring layer composed of a layer (A) brought into contact with an electric charge generating layer and a layer (B) not brought into contact with the generating layer is formed, a butadiene compd. and a distyryl compd. represented by prescribed general formulae are incorporated into the layer A and one or more among a hydrazone compd., a diamine compd. and a triphenylamine compd. represented by prescribed general formulae into the layer B. The layer A has superior injecting and transferring characteristics and the layer B has superior environmental stability such as oxidation stability. A separated function type org. sensitive body having high sensitivity and superior durability is obtd.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a photoreceptor having a functionally separated laminated structure in which a charge transport layer has a two-layer structure and each layer contains a specific charge transport substance. Prior Art and Problems Laminated organic photoreceptors are intended to improve sensitivity and other characteristics by separating charge generation and charge transport functions into separate layers and materials. In general, in a laminated organic photoreceptor, the charge transport layer is formed thicker than the charge generation layer, so that it is less susceptible to scratching and other effects when the photoreceptor is used, and has excellent printing durability. Due to the fact that many charge transport materials have hole transport properties, most of the photoreceptors that have been put into practical use are of the negatively charged type, and are usually composed of a charge generation layer and a charge transport layer on a conductive support. It has a sequential configuration. However, when an organic photoreceptor is used with a negative charge due to corona discharge, large amounts of ozone, nitrogen oxides, etc. are generated.
These compounds adsorb to the surface of the photosensitive layer or chemically deteriorate the surface of the photosensitive layer, which causes problems such as deterioration of the characteristics of the photoreceptor and deterioration of the quality of copied images, especially when used repeatedly. Properties such as chemical stability against ozone, NOx, etc., environmental stability against temperature, humidity, etc., and mechanical strength are also required. In addition, in order to achieve high sensitivity, it goes without saying that the charge transport layer must have transport properties with excellent carrier mobility, and the carriers generated in the charge generation layer must be quickly injected into the charge transport layer. Another important factor is whether or not it will work. Various charge-generating substances and charge-transporting substances are known to be used in laminated organic photoreceptors, and there is a wide range of choices. However, the efficiency of carrier injection from the charge generation layer to the charge transport layer varies greatly depending on the combination of charge generation material and charge transport material that make up the photoreceptor, and it is difficult to fully utilize the characteristics of each material. The combination is important. Generally, in order to increase injection efficiency, a charge transport substance with a low ionization potential (Ip) is used. However, charge transport substances with a low ionization potential are easily oxidized, so their chemical stability may be affected. It is not possible to obtain an excellent photoreceptor. As a means to solve the above-mentioned problems, many studies have been made on surface protective layers. Examples of this surface protective layer have been proposed, such as those provided with an insulating film on the surface of the photosensitive layer, or those provided with a low-resistance protective layer, but a fully satisfactory one has not yet been obtained. . Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and provides a functionally separated organic photoreceptor (substrate + charge generation layer and charge transport layer) which is highly sensitive and has excellent durability. The purpose is to provide. This objective is achieved by further separating the functions of the charge transport layer and laminating a charge transport layer with excellent injection properties and transport properties and a charge transport layer with excellent environmental stability such as oxidation resistance stability. Means for Solving the Problems, that is, the present invention provides a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are sequentially provided on a conductive substrate, in which the charge transport layer includes at least a layer in contact with the charge generation layer and a charge generation layer. The present invention relates to a functionally separated photoreceptor characterized in that it consists of two layers, one of which is not in contact with the other. Of the two-layer charge transport material, the layer in contact with the charge generation layer contains one or more types of charge selected from a butadiene compound represented by the following general formula [I] and a distyryl compound represented by the following general formula (If). configured to contain a transport material: A r,
A r4 [wherein, Art, Ar, , Ar3, A
r4 is each an aryl group, and at least one has a substituent]; Ar, R. [In the formula, Ars, Ar6, and Ary are each an aryl group, and at least one has a substituent; A is an alkylene group that may each have a substituent; an arylene group or a divalent heterocyclic group; R3 represents hydrogen, an alkyl group, an aralkyl group, or an aryl group, each of which may have a substituent. Of the two-layer charge transport material, the layer not in contact with the charge generation layer is a hydrazone compound represented by the following general formula (n[), a diamino compound represented by the following general formula (ff), or the following general formula [V ]; Rs Rs [wherein R2 is an aryl group, an alkyl group, an aralkyl group which may have a substituent, or Heterocyclic group; R1 is an aryl group or heterocyclic group that may have a substituent; R4 is a heterocyclic group that may have a substituent, an aryl group that may have a substituent, or an aralkyl group + RI is an aryl group, an alkyl group, an aralkyl group, or a hydrogen atom which may have a substituent; R8 and R1 or R4 and R, may be taken together to form a ring]; Rs Rs [in the formula Ar is an arylene group that may have a substituent; R1, R7, R, and R9 are an alkyl group that may have a substituent, an aryl group that may have a substituent,
or an aralkyl group which may have a substituent]
: [In the formula, R1°, R11, and R12 are each a hydrogen atom,
represents an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group or a substituted amino group]. The compound represented by the general formula [I] or [II] is excellent in not only charge transport ability but also injection efficiency of charges generated in the charge generation layer, and contributes to achieving high sensitivity. In the general formula (1), A'1 to Ar are each an aryl group such as phenyl, and at least one of these groups is a halogen atom, a lower alkoxy group, an N-substituted amino group, or a lower alkyl group. Among these substituents, preferred is an N-substituted amino group. The butadiene compound represented by the general formula [I] is
Specific examples include, but are not limited to, the following. KI! H3 In the general formula (n), Ar6 to Ary are each an aryl group such as phenyl, and at least one of these groups is one or more of a lower alkoxy group, an N-substituted amino group, or a lower alkyl group. It is preferable to have a substituent of Particularly preferred among these substituents is an N-substituted amino group. When none of Ar5 to Ar7 has any substituent, at least one of Ar5 to Ar7 is a residue of a heterocycle containing a nitrogen atom or an oxygen atom (for example, carbazole, dioxindane, etc.). You can. A
If none of r5 to Ar7 has the above-mentioned substituents or is not the above-mentioned heterocyclic residue, the sensitivity will be poor and the compatibility with the resin will be poor. In the general formula [11), R1 represents a hydrogen atom, a lower alkyl group of C1 to C1, an aralkyl group such as benzyl, or an aryl group such as phenyl, and these groups are substituted with any of the substituents explained for Ar5 to Ar7. may have. In the general formula [■], A represents an arylene group such as phenylene, or a divalent heterocyclic group such as thiol or 7-ran, and the group also has a substituent such as (alkyl group, alkoxy group). You can. Specific examples of the distyryl compound represented by the general formula CI+3 include the following compounds. (Hereinafter, blank space) The compound represented by the general formula (I[[), (IV) or [V] has excellent ozone oxidation resistance, environmental stability, etc. in addition to the charge transport function. In the present invention, durability can be imparted by providing such a charge transport substance on the surface side of the charge transport layer. In the general formula CIII), R represents an aryl group such as phenyl or naphthyl, and may have a substituent such as an alkyl group. Alternatively, an aralkyl group such as benzyl or 7-enethyl, or a lower alkyl group of 01 to C4 may be used. R1 is an aryl group such as phenyl or naphthyl, and may have a substituent such as an alkyl group. Alternatively, it may be a heterocyclic group such as a carbazole ring or a dioxindane ring. R4 is an aryl group such as phenyl or naphthyl, and may have a substituent such as a di-substituted amino group, an alkoxy group, or an alkyl group. Or, it is a heterocyclic group such as carbazole, phenothiazine, tetrahydroquinoline, etc.
These groups may have substituents such as 01-C1 lower alkyl groups. Further, R may be an aralkyl such as benzyl or 7-enethyl. R4 is particularly preferably an aryl group containing a di-substituted amino group; otherwise, the above-mentioned heterocycle containing a nitrogen atom is preferable. R represents a hydrogen atom, an aryl group such as phenyl or naphthyl, a Cl to C4 lower alkyl group, or an aralkyl group such as benzyl or phenethyl, and the aryl group is an alkyl group,
It may have a substituent such as an alkoxy group or a halogen atom. R2 and R3 or R4 and R1 may be taken together to form a ring such as fluorene or indene. Specific examples of the hydrazone compound represented by the general formula Cl11) include the following compounds. C,H. Cz Hs' 8 Formula (IV) Silk, 'Ara represents an arylene group such as haphenylene, diphenylene, triphenylene, pyrene, anthracene, etc., lower alkyl group of % CI to C1, C
It may have a substituent such as a 1 to C4 lower alkoxy group, a halogen atom, or a hydroxy group. R6, R7, R, and R1 are each C1 to C4
represents a lower alkyl group, an aralkyl group such as benzyl or phenethyl, or an aryl group such as phenyl or naphthyl. These groups may have a C1 to C4 lower alkyl, a halogen atom such as bromine, or chlorine as a substituent. As the diamino compound represented by the general formula [IV],
Specifically, the following compounds can be mentioned. H, C-rich tH6 [881 [90j In the general formula (V), RIG, R11 and R1 are each a hydrogen atom, C, -C, lower alkyl group, C8 to C4
Lower alkoxy groups, halogen atoms such as chlorine and bromine, 0
It may be a di-substituted amino group substituted with 1 to C, lower alkylcarbonyl, or a dialkyl group, dialkyl group, diaryl group, or the like. Specific examples of the triphenylamine compound represented by the general formula [v] include the following compounds, but the triphenylamine compound is not limited to these compounds. H, C Next, a case in which the charge transport layer of the present invention is used to form a laminated photoreceptor according to the present invention in which a charge generation layer and a charge transport layer are laminated on a conductive support will be specifically described. Here, the conductive support in the photoreceptor may be a sheet or drum-shaped foil or plate of copper, aluminum, gold, silver, platinum, iron, palladium, nickel, etc., or a plastic film made of these metals. etc. by vacuum deposition, electroless plating, etc., or a layer of conductive compounds such as conductive polymer, indium oxide, tin oxide, etc. is formed by coating or vapor deposition on a support such as paper or glass film. You can use the To form a charge generating layer on such a conductive support, the charge generating material is deposited on the conductive support by vapor deposition or glasstic polymerization, or the charge generating material is deposited in a solution containing an appropriate resin. This dispersion is coated on a conductive support and dried. Note that this charge generation layer has a thickness of 0.01 to 2
μm, preferably 0.11-1tt. Here, examples of the charge generation material used in the charge generation layer include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthine dyes,
cyanine dyes, styryl dyes, pyrylium dyes,
Organic pigments and dyes such as azo pigments, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, induthrone pigments, squarylium pigments, phthalocyanine pigments, and selenium Inorganic materials such as selenium-arsenic, selenium-arsenic, cadmium sulfide, zinc oxide, titanium oxide, and amorphous silicon can be used. In addition, as the resin used with this charge generating material, thermoplastic resins, thermosetting resins, photocuring resins, photoconductive resins, etc., which are known per se, can be used. Examples of resins include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetate maleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, polyvinyl acetal,
Polyester, phenoxy resin, (meth)acrylic resin, polystyrene, polycarbonate, polyarylate,
Thermoplastic resins such as polysulfone, polyethersulfone, ABS resin, phenol resins, epoxy resins, urethane resins, melamine resins, incyanate resins, alkyd resins, silicone resins, curable resins such as thermosetting acrylic resins, polyvinyl carbazole Photoconductive resins such as polyvinylpyrene can be mentioned. However, it is not limited to these. Then, the above charge generating material is combined with these resins,
Alcohols such as methanol, ethanol, isopropanol, etc., ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketonone, N,N-dimethylformamide, N
, amides such as N-dimethylacetamide, sulfoxides such as dimethyl sulfoxide, tetrahydrofuran,
Ethers such as dioxane, cellosolve, carpitol, esters such as methyl acetate, ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, carbon tetrachloride, trichloroethane, benzene, toluene, xylene, ligroin, A photoreceptor liquid prepared by dispersing or dissolving in an organic solvent such as an aromatic compound such as monochlorobenzene or dichlorobenzene is coated on the above conductive support and dried to form a charge generation layer. Here, methods for applying the above-mentioned coating liquid onto the conductive support include dip coating method, ring coating method, spray coating method, spinner coating method, blade coating method, roller coating method, and wire bar coating method. Various coating methods such as can be used. In order to provide a charge transport layer on the charge generation layer formed in this manner, the binder resin as described above and a charge transport material selected from compound [I] or (If) (a mixture of two or more of them) are used. ) is dissolved in an appropriate solvent as mentioned above, and this coating solution is applied onto the charge generation layer by the method described above and dried to form a layer of 1 to 40 μm, preferably 5 to 5 μm.
A charge transport layer (referred to as a first charge transport layer) having a thickness of 30 μm is formed. . If the thickness of the first charge transport layer is less than 1 μm, coating properties will be poor, resulting in unevenness and poor injection properties. Also, if it is thicker than 40 μm, the repeatability will deteriorate,
Sensitivity changes become large. Next, in the same manner as the first charge transport layer, compound (II
A charge transport material selected from I), (IV) or (V) (
A coating liquid may be prepared by using a mixture of two or more types, and the coating liquid is coated on the first charge transport layer and dried.
A charge transport layer (second charge transport layer) having a thickness of preferably 5 to 10 μm is formed. When the film thickness of the second charge transport layer is thinner than lpm, the coating properties are poor, unevenness occurs, and the characteristics change significantly due to abrasion during printing. Further, when the thickness is more than 20 μm, the repeatability becomes poor, and especially the sensitivity change becomes large. The total thickness of the charge transport layer is 5 to 50 μm, preferably 1 μm.
It is formed to have a thickness of 0 to 30 μm. If the total thickness of the charge transport layer is less than 5 μI, the charge retention ability will be low and the printing durability will also be poor. Furthermore, if the thickness is greater than 50 μm, the sensitivity change will increase. The first and second charge transport layers may further contain known sensitizers, leveling agents, antioxidants, and the like. Furthermore, in any of the photoreceptors obtained as described above, an intermediate layer can be provided between the conductive support and the photosensitive layer, if necessary. Here, the materials used for the intermediate layer include polyimide,
Polymers such as polyamide, nitrocellulose, polyvinyl butyral, and polyvinyl alcohol can be used as they are, or low-resistance compounds such as tin oxide, indium oxide, antimony oxide, titanium oxide, etc. can be dispersed in hardening resins such as acrylic, urethane, epoxy, and melamine. The things that caused
A vapor deposited film of aluminum oxide, zinc oxide, silicon oxide, zirconium oxide, etc. is suitable, and it is desirable to form the film so that the film thickness is 5 μm or less. Examples will be described below. Example 1 - 1 part by weight of r-type metal phthalocyanine - 1 part by weight of polyvinyl butyral (S-LEC BL-3
) Tetrahydro 7ran 98 parts by weight The above material was treated with a paint conditioner for 2 hours to prepare a coating solution for a charge generation layer. After drying the coating solution on an aluminum drum, the film thickness is 0.
A charge generation layer was formed by coating to a thickness of 25 μm by a dipping method.・Compound (4) 10 parts by weight ・Polycarbonate (K-1300) 10 parts by weight ・Dichloromethane 90 parts by weight The above materials were mixed, dispersed and dissolved to form a first charge transport layer coating solution, and the previously formed charge generation layer was mixed and dissolved. A first charge transport layer was formed thereon by a ring coating method so that the film thickness after drying was 15 μm.・Compound (69) 10 parts by weight ・Polycarbonate (K-1300) I 0 parts by weight ・Dichloromethane 90 parts by weight The above materials were mixed and dispersed and dissolved to form a second charge transport layer coating solution, and the coating liquid for the previously formed first charge transport layer was mixed and dissolved. A second charge transport layer was formed by a spray coating method so that the film thickness after drying was 10 μm. A photoreceptor was obtained as described above. Example 2 Compound [4] used in the first charge transport layer in Example 1
A photoreceptor was produced in the same manner as in Example 1, except that compound [41] was used instead of compound [69] used in the second charge transport layer, and compound [73] was used instead of compound [69]. Comparative Examples 1 and 2 Photosensitive in the same manner as in Examples 1 and 2 except that in Examples 1 and 2, the second charge transport layer was not formed and the first charge transport layer was formed to have a film thickness of 25 μm. The body was created. Example 3 Compound used in the second charge transport layer in Example 1 [
Example 1 except that compound [96] was used instead of [69]
A photoreceptor was prepared in the same manner as described above. Example 4 - 1 part by weight of diazo compound (CDB) represented by the following structural formula - 1 part by weight of polyester (Vylon 200) -
Cyclohexane 98 parts by weight The above materials were dispersed in a sand mill for 14 hours to prepare a coating solution for a charge generation layer. Example 1 except that the charge generation layer was formed using the above coating liquid.
A photoreceptor was produced in the same manner as described above. Comparative Examples 3.4 and 5 Examples 1.2 and 3 except that in Examples 1, 2 and 3, the first charge transport layer was not formed and the second charge transport layer was formed to have a thickness of 25 μm. A photoreceptor was prepared in the same manner as described above. Comparative Example 6 A photoreceptor was produced in the same manner as in Example 4 except that the second charge transport layer was not formed and the first charge transport layer was formed to have a thickness of 25 μm. Comparative Example 7 A photoreceptor was produced in the same manner as in Example 4 except that the first charge transport layer was not formed and the second charge transport layer was formed to have a thickness of 25 μm. Using a commercially available electrophotographic copying machine (manufactured by Minolta Camera Co., Ltd.: EP-50), the obtained photoreceptor was subjected to corona discharge at -6 kV, and the initial surface potential VO (V) and the initial surface potential were 1 The exposure amount E r/t(lu
x-see), the exposure amount E required to attenuate the initial surface potential to -100V. (lux-sec) was measured. Furthermore, the image quality at this time was also evaluated. After making another 5000 copies, vo, E,
/7, the electrostatic properties and image quality of EIOo were evaluated. In the image quality evaluation, "O" indicates good quality, and "x" indicates there is a problem. The above results are shown in Table 1. (Hereinafter referred to as margins) As is clear from Table 1, in Examples 1 to 4, good electrostatic characteristics and image quality were obtained both at the initial stage and after 5,000 sheets, but in the comparative example, the sensitivity However, I couldn't find anything that satisfied me in terms of image quality. Further, on the photoreceptor produced in Example 1, a surface protective layer (1000 layers) made of amorphous carbon was formed using a plasma CVD method. As a plasma CVD device, JP-A-63
An apparatus similar to that shown in Japanese Patent Publication No. -97961 was used, and the manufacturing conditions were set as follows.

[Plasma conditions]

- Raw material gas and gas flow rate Hydrogen gas 300 [sccm] Butadiene gas l 5 [sccml/Vacuum chamber pressure
0,3 [Torr]・Substrate temperature
50(”C)・Discharge frequency 80[
KH2]・Discharge power 150 [W]・Discharge time 3.5E/min When an attempt was made to evaluate the photoreceptor, it was found that the same suitable performance as the photoreceptor obtained in Example 1 was obtained in terms of both electrostatic properties and image characteristics. Furthermore, when a 50,000-sheet printing durability test was conducted using a commercially available copying machine (manufactured by Minolta Camera Co., Ltd., EP-50), no scratching was observed, and even after the printing durability test, suitable electrostatic properties and Image characteristics can be obtained. Effects of the Invention According to the present invention, a photoreceptor with high sensitivity and excellent durability can be obtained by forming the charge transport layer into a two-layer structure and allowing each layer to contain a specific charge transport substance.

Claims (1)

[Scope of Claims] 1. In a functionally separated photoreceptor in which a charge generation layer and a charge transport layer are sequentially provided on a conductive substrate, the charge transport layer includes at least a layer in contact with the charge generation layer and a layer not in contact with the charge generation layer. A functionally separated photoreceptor characterized by consisting of two layers. 2. Claim 1, wherein the layer in contact with the charge generation layer contains one or more charge transport materials selected from a butadiene compound represented by the following general formula [I] and a distyryl compound represented by the following general formula [II]. Functionally separated photoreceptor described; ▲There are mathematical formulas, chemical formulas, tables, etc.▼[I] [In the formula, Ar_1, Ar_2, Ar_3, and Ar_4 are each aryl groups, and at least one has a substituent], ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [II] [In the formula, Ar_5, Ar_6, and Ar_7 are each an aryl group, and at least one has a substituent; A is an alkylene group that may each have a substituent. ; Represents an arylene group or a divalent heterocyclic group; R_1 is hydrogen;
represents an alkyl group, an aralkyl group, or an aryl group, each of which may have a substituent.] 3. The layer not in contact with the charge generation layer is selected from a hydrazone compound represented by the following general formula [III], a diamino compound represented by the following general formula [IX], or a triphenylamine compound represented by the general formula [V]. The functionally separated photoreceptor according to claim 1, which contains one or more charge transport materials; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [III] group, alkyl group, aralkyl group, or heterocyclic group; R_3 is an aryl group or heterocyclic group that may have a substituent; R_4 is a heterocyclic group that may have a substituent, or a heterocyclic group that may have a substituent. Good aryl group or aralkyl group; R_5 is an aryl group, alkyl group, aralkyl group, or hydrogen atom that may have a substituent; R_2 and R_3 or R_4 and R_5 may be taken together to form a ring] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [IV] [In the formula, Ar_3 is an arylene group that may have a substituent; R_6, R_7, R_8, and R_9 are each an alkyl group that may have a substituent. [V] [In the formula, R_1_0, R_1_1, R_1_2 are each represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, an alkoxycarbonyl group, or a substituted amino group].