JPS6023450A - Photo-sensitive material for electrophotography - Google Patents

Abstract

PURPOSE:To provide a photo-sensitive material for electrophotography, producible easily, and having stable characteristics to the repetitive use of the material, by using a specific disazo dye as a charge-generating material, and adding the material in the photo-sensitive layer. CONSTITUTION:The objective photo-sensitive material is obtained by coating an electrically conductive substrate with a photo-sensitive layer comprising a combination of (A) a charge-generating material consisting of a disazo dye of formula I [R<1> and R<2> are lower alkyl, (substitued) aralky, (substituted) aromatic group, (substituted) heterocyclic group, or R<1> and R<2> together form a ring] and (B) a charge-transfer material consisting of e.g. the compound of formula II[R<10> is (substituted) alkyl; R<11> is alkyl, aralkyl or aryl; R<12> is H, halogen, alkyl, alkoxy, nitro, etc.].

Description

[Detailed description of the invention] Technical field The present invention relates to a photoreceptor for electrophotography.

PRIOR ART Photoconductors for electrophotography include inorganic photoconductors such as those using selenium and its alloys, or photoconductors with dye-sensitized zinc oxide dispersed in a binder resin, and organic photoconductors. Typical examples include those using a charge transfer complex of 2,4,7-) dinitro-9-fluorenone (TNF) and poly-N--dylcarnozole (P'VK). known as.

However, while these photoreceptors have many advantages, they also have various disadvantages.

For example, the currently widely used selenium photoreceptor has difficult manufacturing conditions, high manufacturing costs, and is difficult to process into a belt shape due to its lack of flexibility.
It is also sensitive to heat and mechanical shock, so care must be taken when handling it.

Zinc oxide photoreceptors are low in cost because they can be manufactured by applying inexpensive zinc oxide to a support, but they generally have low sensitivity, surface smoothness, hardness, tensile strength, and durability. It has mechanical drawbacks such as abrasion, and there are many problems with durability as a photoreceptor for plain paper copying machines that are usually used repeatedly.

Furthermore, a photoreceptor using a charge transfer complex of TNF and PVK has low sensitivity and is unsuitable as a photoreceptor for high-speed copying machines.

In recent years, extensive research has been carried out to eliminate the drawbacks of these photoreceptors, and in particular, various organic photoreceptors have been proposed. Among these, there is a layer (hereinafter referred to as "charge generation layer") containing a substance that generates charge carriers when irradiated with light (hereinafter referred to as "charge generation material"), and a layer that receives and transports the generated charge carriers. A laminated photoreceptor consisting of a layer (hereinafter referred to as a "charge transport layer") mainly composed of a substance (hereinafter referred to as a "charge transport material") generally has higher sensitivity and chargeability compared to conventional organic photoreceptors. Due to its stable properties, it has attracted attention as a photoreceptor for plain paper copying machines, and some are in practical use.

As a conventional laminated photoreceptor of the type (1) i! A thin layer of a perylene derivative vacuum-deposited is used as the charge generation layer, and an oxadiazole derivative is used as the charge transport layer (
(See US Pat. No. 3,871,882).

(2) A thin layer formed by coating an organic amine solution of Chlordiane blue as a charge generation layer, and a hydrazone compound used as a charge transport layer (Japanese Patent Publication No. 55-423
(see Publication No. 80) and the like are known.

However, although conventional photoreceptors of this type have many advantages, they also have various drawbacks as described below.

The photoreceptor using the perylene derivative and oxadiazole derivative shown in (1) above has a high manufacturing cost because its charge generation layer is formed by vacuum deposition.

The photoreceptor using chlordiane blue and a hydrazone compound shown in (2) above uses an organic amine (which is generally difficult to handle) as a coating solvent for forming a charge generation layer.
For example, it is necessary to use ethylenediamine), which has disadvantages in producing a photoreceptor.

Purpose The present invention provides an electrophotographic photoreceptor that can be easily manufactured and is suitable for repeated use.

Structure The electrophotographic photoreceptor of the present invention has the following general formula (1) (% formula %) on a conductive support (in the formula, R1 and R2 are a lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aralkyl group). Represents an aromatic group, a substituted or unsubstituted heterocyclic group. R1 and R2 may be the same or different, or R1 and R2 may jointly form a ring.) It is characterized by being provided with a photoconductive layer (photosensitive layer) containing the represented disazo compound.

Here, the lower alkyl group in general formula (1) includes a methyl group, ethyl group, propyl group, etc., the aralkyl group includes a benzyl group, phenethyl group, etc., and the aromatic group includes a phenyl group, naphthyl group, anthryl group, etc. , pyrenyl group, anthraquinonyl group, etc., heterocyclic groups include chenyl group, furyl group, pyridyl group, carnozolyl group, etc., and the ring formed by R1 and R2 includes hexylidene ring, pentylidene ring, benzylidene ring, etc. Examples include pentylidene ring and dipenzopentylidene ring. Examples of substituents on the aralkyl group, aromatic group, heterocyclic group, or ring formed by R1 and R2 include lower alkyl groups, lower alkoxy groups, halogen atoms, cyano groups, nitro groups, and lower dialkylamino groups. .

Incidentally, the present invention is based on the inventor's extensive studies to achieve the above-mentioned object, and the discovery that the use of a specific disazo pigment (disazo compound) is extremely useful for electrophotographic photoreceptors. This was done based on the following. Furthermore, the electrophotographic photoreceptor of the present invention is not limited to a single-layer type, but rather is preferably a laminated type in which the photosensitive layer is composed of a charge generation layer and a charge transport layer. In such a laminated electrophotographic photoreceptor, the charge generation layer is formed of a layer containing a disazo pigment represented by the above general formula (1)b.The present invention will be described in more detail below. First, specific examples of the disazo compound represented by the general formula (1) used in the present invention are as follows.

These disazo compounds include the diazonium salts described in JP-A No. 54-22834 and the corresponding cassilla (2-hydroxy-3-naph F-tonic acid hydrazides).
can be easily produced by reacting a suitable organic solution with a base in, for example, N,N-dimethylformamide (DMF) to cause a coupling reaction.

By the way, as described earlier, the photoreceptor of the present invention is
The photosensitive layer contains a charge generating substance represented by the general formula (1), but in an actual photoreceptor, the charge generating substance and the charge transporting substance are combined to form the photosensitive layer (photoconductive layer). layer) is formed.

Although the charge transporting substance used in the present invention is not specified, typical examples thereof are as follows.

CRlo is an alkyl group such as a methyl group or an ethyl group, or a 2-
Substituted alkyl groups such as chloroethyl group and 2-hydroxyethyl group. R11 is a methyl group, an alkyl group such as ethyl group, an aralkyl group such as benzyl group, an aryl group such as 7-ethyl group, and B11 is a hydrogen atom, chlorine, bromine, etc. It represents a halogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkoxy group such as a methoxy group, an ethoxy group, a tetrapoxy group, a butoxy group, a dialkylamino group, or a nitro group. ] (Ar' represents a 7-tyl group, an anthryl group, a styryl group, or a substituted product thereof, RlB represents an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, or an aryl group such as a phenyl group. Examples of substituents on the anthryl group and styryl group include alkyl groups such as methyl group and ethyl group, alkoxy groups such as methoxy group and ethoxy group, and dialkylamino groups such as dimethylamino group and diethylami7 group. ] (R14, R11+ or HI7 is a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, or a propyl group, an alkoxy group such as a methoxy group, an ethyl group, or a propoxy group, or a halogen atom such as chlorine or , =) represents an a group or a hydroxyl group, R16 is a hydrogen atom, a methyl group, an ethyl group,
Alkyl groups such as propyl groups, alkoxy groups such as methoxy, ethoxy, and propoxy groups, 7 dialkylamino groups such as dimethylamino and diethylamino groups, dialkylamino groups such as diarylamino groups, and diaryls such as 7 diphenylami groups. An amino group, a halogen atom such as chlorine or bromine, a nitro group or a hydroxyl group. R1δ represents an alkyl group such as a methyl group or an ethyl group, an aralkyl group such as a benzyl group, or an aral group such as a phenyl group. ] 20R19 (R19s Rn, 82m or R22 is a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, or a propyl group, an alkoxy group such as a methoxy group, an ethoxy group, or a propoxy group, or a dialkylamino group such as a dimethylami7 group or a diethylamino group) , represents a halogen atom such as chlorine or bromine, a nitro group or a hydroxyl group.] (Raa is an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted heterocyclic group, R2
4 or R21l represents a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a chloro-substituted alkyl group, a hydroxy-substituted alkyl group, a substituted or unsubstituted aralkyl group, and B24 and 1211 are bonded to each other. may form a nitrogen-containing heterocycle.H2S or Rn is a hydrogen atom, a methyl group, an ethyl group, a pro2 group,
It represents an alkyl group such as a butyl group, an alkoxy group such as a methoxy group or an ethoxy group, or a halogen atom such as chlorine or bromine. Examples of the heterocyclic group of H2S include a pyridyl group, a furyl group, a chenyl group, an indolyl group, a pyridyl group, a quinolyl group, and a carbazolyl group.

Examples of substituents on the phenyl group or heterocyclic group of H2S include alkyl groups such as methyl group and ethyl group, and alkoxy groups such as methoxy group and ethoxy group.

Examples of the aralkyl group of R24 or RQ include a benzyl group, and substituents on the aralkyl group include halogen atoms such as chlorine and bromine, methyl groups,
Examples include alkyl groups such as ethyl groups, and nitro groups. An example of the heterocycle formed by bonding 114 and Roll to each other is a morpholine ring. ] [R28 is a hydrogen atom, a halogen atom such as chlorine, bromine,
R19 is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group or an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a dialkylamine group such as a dimethylamino group, a diethylamino group or a dibutylamino group.
dialkylamino Rs0 such as a dibenzylamino group, a chloro/I/N-substituted dibenzylamino group, and the like represents a hydrogen atom, a halogen atom such as chlorine or bromine, one methyl group, one ethyl group, or other alkyl group. ] CHIS is a hydrogen atom, a halogen atom such as chlorine, bromine,
Alkyl group such as methyl group, ethyl group, butyl group, alkoxy group or cyano group such as methoxy group, ethoxy group, butoxy group, Ba2 or Rag is hydrogen atom, alkyl group such as methyl group, ethyl group, butyl group, 2 - Substituted alkyl group such as chloroethyl group or 2-hydroxyethyl group, or substituted or unsubstituted benzy/l/ group, R8
4 or Roll is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group, an ethyl group or a butyl group, an alkoxy group such as a methoxy group, an ethoxy group or a butoxy group, or a dialkyl group such as a dimethylamino group or a diethylamino group. Represents an amino group. Examples of substituents on the benzyl group of R112 or Ram include alkyl groups such as methyl group and ethyl group, alkoxy groups such as methoxy group and ethoxy group, and nitro group.0] (Ar' is an N-alkylcarbazolyl group) and examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group.]CR16, R8?, Ba
9 is a hydrogen atom, a halogen atom such as chlorine or bromine, an alkyl group such as a methyl group or an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a nitro group or an amide group, R3
8 Phosphorous hydrogen atoms, halogen atoms such as chlorine and bromine, alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, dialkylamino groups such as dimethylamine, diethylamino and dimethylamino groups,
Substituted or unsubstituted dialkylamino groups such as dibenzylamino group, OA/substituted dibenzylamino group, methyl-substituted dibenzylamino group, methoxy-substituted di(andylamino/group), N-methyl-N-benzylamino group, etc. N-
Alkyl-N-aralkylami7 groups, cardoxy group or its ester, amino group, hydroxy group, cyano group,
Represents 7 acetylamide groups. [R' represents an N-alkyl group such as a lunosezolyl group, a pyridyl group, a chenyl group, an indolyl group, a furyl group, or a substituted or unsubstituted naphthyl group, styryl group or anthryl group. Examples of substituents on naphthyl, styryl, and anthryl groups include alkyl groups such as methyl and ethyl groups, alkoxy groups such as methoxy and ethoxy groups, and dialkylamide groups such as dimethylamino and diethylamino groups. ] (R41, H" is a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a butyl group, an alkoxy group such as a methoxy group, an ethoxy group, a butoxy group, a halogen atom such as chlorine or bromine, a dimethylamino group, or a diethylamino group) represents a dialkylamino group such as, nl represents 0 or 1.

] (H143, R44 are hydrogen atoms, alkyl groups such as methyl group, ethyl group, alkoxy groups such as methoxy group, ethoxy group, halogen atoms such as chlorine, H411, H@ are methyl group, ethyl group, propyl group, butyl group) an alkyl group such as a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, B4? represents a hydrogen atom, a substituted or unsubstituted phenyl group. Examples of aryl groups include phenyl groups. Substituents on aralkyl or aryl groups include alkyl groups such as methyl, ethyl, and butyl; alkoxy groups such as methoxy and ethoxy; halogen atoms such as chlorine,
Examples include dialkylamino groups such as dimethylamino group and diethylamino group. ] (H411 and R4O represent an alkyl group such as a methyl group or an ethyl group, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group. Examples of substituents include an alkyl group such as a methyl group or an ethyl group, or a methoxy group. , an alkoxy group such as an ethoxy group.] (R2O and R11 represent the same groups as R48 and R49 above.) [R52 is a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or a substituted or unsubstituted phenyl group. or represents an unsubstituted N-alkylcarnozolyl group. Here, 85M is a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or a methyl group, an ethyl group, a propyl group,
It represents an alkyl group such as a butyl group, a substituted or unsubstituted aralkyl group such as a benzyl group, a substituted or unsubstituted aryl group such as a phenyl group, and also R114 and R
″′ may form a ring.), where m is 0, 1,
Represents an integer of 2 or 3, and when m is 2 or more, R11
8 may be the same group or a pot group. R” or R65
Examples of substituents on the aralkyl group or aryl group include alkyl groups such as methyl, ethyl, zotetragyl, and butyl, alkoxy groups such as methoxy and ethoxy, halogen atoms such as chlorine, and dimethylamino groups. , dialkylamino groups such as diethylamino groups, and the like. ] Further, specific examples of these charge transport substances are as follows. Structural formula CH.

Compound Hatsuyu structure formula compound A horizontal structure formula compound point structure formula compound point structure formula compound point structure formula compound point structure formula compound genus structure formula compound point structure formula compound structure Formula Hardware Shop Structure Formula In addition to the above-mentioned exemplified compounds, polymeric substances include poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazole, polyvinylpyrene, or bupylene-formaldehyde condensation tM resin, N Condensation resins such as -ethylcartumazole-formaldehyde condensation resin, and low molecular weight substances such as oxazole derivatives, oxadiazole derivatives, and nitro derivatives of fluorenone are all effective.

The accompanying drawing is an enlarged cross-sectional view of a typical electrophotographic photoreceptor according to the present invention, and FIG. One in which a single-layer photosensitive layer 41 is provided, and FIG. 2 shows one in which a charge generation layer 22 and a charge transport layer 32 are provided on a conductive support 11 to form a multilayer photosensitive layer 42. ing. Compared to the former, the latter (as shown in Figure 2)
A laminated type electrophotographic photoreceptor is more advantageous in many respects. Note that the photosensitive layer can also be formed by dispersing a disazo compound represented by the general formula (1) in a binder resin, without using the above-mentioned charge transporting substance.

As the conductive support 11 used in the present invention, metal plates, metal drums, or metal foils made of aluminum, niracle, chromium, etc.; - and paper or plastic films coated with or impregnated with a conductive substance.

In the product [iL photoreceptor, the charge generation layer 22 is made of a solution in which a specific disazo compound represented by the general formula (1) shown above is made into fine particles by a means such as a Seel mill and dispersed in a suitable solvent. or, if necessary, a dispersion in which a binder resin is dissolved therein is applied and formed on the conductive support 11, and if necessary, the surface is finished by a method such as 9-polishing. The film thickness was adjusted accordingly.

The thickness of the charge generation layer 22 is 0.01 to 5 μm, preferably 0.05 to 2 μm, and the proportion of the disazo compound in the charge generation layer 22 is 10 to 100% by weight, preferably 30 to 1% by weight.
~95% by weight.

If the thickness of the charge generation layer 22 is 0.01 μm or less, sensitivity is poor, and if it is 5 μm or more, potential retention is poor.

Furthermore, if the proportion of the disazo pigment in the charge generation layer 22 is less than 10% by weight, the sensitivity is poor.

The charge transport layer 32 is formed by coating a solution prepared by dissolving the various charge transport materials described above and a binder resin in a suitable solvent such as tetrahydrofuran onto the charge generating layer H22. Here, the proportion of the charge transport substance contained in the charge transport layer 32 is 10 to 80% by weight, preferably 25% by weight.
The film thickness is 2 to 100 μm, preferably 5 to 40 μm. If the proportion of the charge transport substance contained in the charge transport layer 32 is less than 10% by weight, the sensitivity will be poor, and if it is more than 80% by weight, the film will become brittle, crystals will precipitate, and the charge transport layer 32 will become cloudy, which is undesirable. . Furthermore, if the thickness of the charge transport layer 32 is 2 μm or less, the potential is not maintained well;
If the thickness is 100 μm or more, the residual potential becomes high.

Examples of the binder resin for the charge generation layer 22 used here include polyester resin, butyral resin, ethyl cellulose resin, epoxy resin, acrylic resin, vinylidene chloride resin, polystyrene, polybutadiene, and copolymers thereof. These can be used alone or in a mixture of two or more.

Examples of the binder resin for the charge transport layer 32 include polycarbonate resin, polyester resin, polystyrene, polyurethane resin, epoxy resin, acrylic resin, silicone resin, and copolymers thereof. Or, two or more types are used in a mixed state.

Furthermore, various additives can be added to the charge transport layer 32 for the purpose of improving flexibility or durability. Additives used for this purpose include halogenated roughheins, dialkyl phthalates, silicone oils, and the like.

Furthermore, in the photoreceptor of the present invention, if necessary, a layer (21J) is provided between the conductive support 11 and the charge generation layer 22, an intermediate layer is provided between the charge generation layer 22 and the charge transport layer 32, and An overcoat layer may also be provided on the charge transport layer 32.

Next, the present invention will be specifically explained using Examples, but the embodiments of the present invention are not limited thereto.

Example 1 76 parts by weight of disazo compound A1-1, 1260 parts by weight of a polyester resin (Pyrin 200, manufactured by Toyobo Co., Ltd.) in a tetrahydro 7 run solution (solid content concentration 2%) and 3700 parts by weight of Tetrahydro T27 run were added. The resulting dispersion was pulverized and mixed in a Lumil, and the resulting dispersion was applied using a doctor blade onto the aluminum surface of an aluminum-deposited polyester paste (conductive support). A generation layer was formed.

On the other hand, 2 parts by weight of charge transport substance A229, 2 parts by weight of polycarbonate resin (1300 for Panlight, manufactured by Teijin Co., Ltd.)
After mixing and dissolving 16 parts by weight of tetrahydrofuran and 16 parts by weight of tetrahydrofuran to form a solution, this was applied onto the charge generation layer using a doctor blade, and dried at SOC for 2 minutes and then at 100C for 5 minutes to form a charge with a thickness of about 20 μm. A transport layer was formed, and a laminated type photoreceptor 1 shown in FIG. 2 was prepared.

Examples 2 to 10 Example 1 except that the disazo compound and charge transport substance shown in Table 1 below were used in place of the disazo compound point 1-1 and charge transport substance 2-29 used in Example 1. Photoreceptors 2 to 10 were created in the same manner as described above.

These photoreceptors A1 to A10 were negatively charged by performing -6 KV (7) corona discharge for 20 seconds using an electrostatic copying paper tester (newly manufactured by Kawaguchi Electric Co., Ltd., model 5P428). After that, it was left in a dark place for 20 seconds, and the surface potential Vpo (t/) f was measured at that time. Then, the surface was irradiated with light using a tungsten lamp at an illuminance of 4.5 lux, and the surface potential was determined to be Vpo. Determine the time (seconds) it takes to reach % of
seconds) was calculated. The results are shown in Table-1.

Table 1 In addition, clear images were obtained even after the photoconductor of the present invention was installed in the Ricoh P-500 copier manufactured by Ricoh Co., Ltd. and image output was repeated io and ooo times. Particularly, it can be seen that the photoreceptor of the present invention is also excellent in durability.

Effects As described above, the electrophotographic photoreceptor of the present invention has excellent properties such as being easy to manufacture and having stable characteristics even after repeated use of the photoreceptor.

[Brief explanation of the drawing]

1 and 2 are enlarged sectional views showing two typical sides of the electrophotographic photoreceptor of the present invention.

Claims (1)

[Claims] 1. The following general formula (1) (wherein R1
and R2 represents a lower alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted heterotetracyclic group. Here, R1 and R2
may be the same or different, and R1 and R may jointly form a ring. ) An electrophotographic photoreceptor comprising a photosensitive layer containing a disazo pigment represented by the following formula as an active ingredient.