JPH04177358A - Electrophotographic sensitizer - Google Patents

Abstract

PURPOSE:To secure such an electrophotographic sensitizer that is high in sensitivity and excellent in durability by containing a specific sterile compound in it. CONSTITUTION:It contains a new sterile compound being shown in an equation I. Where, in this equation I, R<1>-R<3> show a hydrogen atom, an alkyl group capable of having a substituent, an alkenyl group, an aralkyl group, an aryl group, and A shows a di-aromatic ring capable of having the substituent or heterocyclic residual group, and Z<1>, Z<2> shown an atomic group being required to form saturated 5-6 rings together with two carbonic atoms of indoline rings. With this constitution, such an electrophotographic sensitizer that is high in sensitivity and excellent in durability is thus securable.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electrophotographic photoreceptor containing a novel styryl compound.

[Prior art and problems]

Conventionally, inorganic photoconductive materials such as selenium, cadmium sulfide, zinc oxide, and silicon have been known to be used as electrophotographic photoreceptors, and have been extensively studied and put into practical use. In recent years, in contrast to these inorganic materials, research into organic photoconductive materials has progressed actively, and some have been put into practical use as electrophotographic photoreceptors. Generally speaking, it is an inorganic material; for example, selenium photoreceptors have problems with thermal stability, deterioration of properties due to crystallization, and manufacturing difficulties, while cadmium sulfide has problems with moisture resistance, durability, and industrial Compared to the current situation, which is not always satisfactory due to problems such as waste disposal, organic materials have good film forming properties, excellent flexibility, light weight, and transparency. Its practical application is increasingly attracting attention because it has advantages such as easy design of photoreceptors for a wide range of wavelengths using a suitable sensitization method. By the way, the photoreceptor used in electrophotography technology is -
The following basic properties are required within the shell: That is, (1) the charging property is high against corona discharge in the dark, (2) there is little leakage (dark decay) of the obtained charged charge in the dark, and (3) the charged charge is reduced by light irradiation. (4) The residual charge after light irradiation is small. However, to date, much research has been conducted on photoconductive polymers such as polyvinylcarbazole as organic photoconductive materials, but these do not necessarily have sufficient film properties, flexibility, or adhesive properties, and as mentioned above, It is difficult to say that the photoconductor has sufficient basic properties as a photoreceptor. On the other hand, with regard to organic low-molecular photoconductive compounds, it is possible to obtain photoreceptors with excellent film properties, adhesion, flexibility, and other mechanical strengths by selecting the binder used to form the photoreceptor. Although possible, it is difficult to find suitable compounds that can retain the properties of high sensitivity. In order to improve this point, organic photoreceptors having higher sensitivity characteristics have been developed by assigning the carrier generation function and the carrier transport function to different substances. A feature of this kind of photoreceptor, which is called a functionally separated type, is that materials suitable for each function can be selected from a wide range, and a photoreceptor with arbitrary performance can be easily created, which has led to a lot of research. has been progressing.

[Purpose of the invention]

As mentioned above, various improvements have been made in the production of electrophotographic photoreceptors, but none satisfy the basic properties and high durability required for photoreceptors listed above. I still haven't gotten enough. An object of the present invention is to provide an electrophotographic photoreceptor having high sensitivity and high durability. Another object of the present invention is to provide a photoreceptor that has high charging characteristics, exhibits almost no decrease in sensitivity even after repeated use, and has a stable charging potential.

[Structure of the invention]

As a result of research into photoconductive substances having high sensitivity and high durability, the present inventors discovered that a novel styryl compound represented by the following general formula CI) is effective, leading to the present invention. RI R2R? R11 (I) (wherein, R1, R2, R3, R4, R5, R6, R7,
R8 represents a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group, an aralkyl group, or an aryl group. A
represents a divalent aromatic ring or a heterocyclic residue which may have a substituent. Zl and Z2 represent an atomic group required to form a saturated 5- to 8-membered ring together with the two carbon atoms of the indoline ring. ) Here, R11R2, R3, R4, R5, R6, R7,
Specific examples of R8 include a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, and a propyl group, an allyl group, a methallyl group,
Alkenyl groups such as 2-methyl-1-propenyl group, aralkyl groups such as benzyl group, methylbenzyl group, chlorobenzyl group, β-phenylethyl group, α-naphthylmethyl group, phenyl group, methoxyphenyl group, tolyl group, Aryl groups such as chlorophenyl group and naphthyl group can be mentioned. Specific examples of A include p-phenylene group, 1
, 5-naphthylene group, 1,4-antrylene group, 1°3
- Divalent groups of aromatic rings such as pyrenediyl group, 2.7-fluorenediyl group, 1°8-fluorenediyl group, 3,6-phenanthreinediyl group, 3.4-thiophenediyl group, 2. 3-pyridinediyl group, 2.3-furandiyl group, 2,4-furandiyl group, 2,5-furandiyl group, 3.7-dibensifurandiyl group, 2.3-pyrazinyl group, 2,5 -Pyrazinediyl group, 2.6-pyrimidinediyl group, 4.6-pyrimidinediyl group, 2.4-quinolinediyl group, 5.6-benzimidazolediyl group, 2
．． 5-pyrrolediyl group, 2,6-pyranediyl group, 3
．． Examples include heterocyclic divalent groups such as 6-pyridazinediyl group, 4,5-pyridazinediyl group, 2,6-carbazolediyl group, and 3,6-carbazolediyl group. Specific examples of Zl and Z2 include those shown in the exemplified compounds described below. These compounds represented by general formula (I) are produced by the methods of the following synthesis examples. Synthesis Example (Synthesis of Exemplified Compound (3)) (II[') Aldehyde of formula (II) (5,27g) and formula (III)
Potassium 1-butoxide (2.71 g) was added to a solution of the phosphonate (4.54 g) of ) in 1,2-dimethoxyethane while keeping the temperature at 0°C. After stirring at the same temperature for 20 minutes and further at room temperature for 1 hour, the reaction mixture was poured into water and extracted with chloroform. The crude product obtained by concentrating the extract was recrystallized from a mixed solvent of benzene and ethyl acetate to obtain 4.13 g of Exemplified Compound (3). Melting point 214.3-215.6°C NMR (δ, ppm, CDC13) 1.45-2.2 (m, 12H), 3.85 (m, 2H), 4.81 (m, 2H),
6, 8-7. 5 (m, 24H) Next, styryl compounds related to the present invention will be illustrated, but the invention is not limited thereto. (Hereinafter, blank spaces) The electrophotographic photoreceptor according to the present invention is obtained by containing one or more styryl compounds as shown above, and has excellent performance. Various methods are known for using these styryl compounds as electrophotographic photoreceptors. For example, a photoreceptor comprising a styryl compound and a sensitizing dye, dissolved or dispersed in a binder resin with the addition of a chemical sensitizer or an electron-withdrawing compound as necessary, on a conductive support. Alternatively, in the form of a laminated structure consisting of a carrier generation layer and a carrier transport layer, the present invention is applied onto a carrier generation layer provided mainly with a carrier generation substance with high carrier generation efficiency, such as a dye or pigment, on a conductive support. A photoreceptor comprising a styryl compound dissolved or dispersed in a binder resin with the addition of a chemical sensitizer or an electron-withdrawing compound as needed, and laminated as a carrier transport layer;
There is a photoreceptor in which the carrier generation layer and the carrier transport layer are laminated in reverse on a conductive support, but the invention can be applied to either case. As a support for producing a photoreceptor using the compound of the present invention, a metal drum, a metal plate, paper treated with electrical conductivity, a plastic film, or a belt-like support is used. Various film-forming binder resins can be used to form the photosensitive layer on these supports depending on the field of use. For example, for use in photoreceptors for copying, polystyrene resin, polyvinyl acetal resin, polysulfone resin, polycarbonate resin, vinyl acetate/crotonic acid copolymer resin, polyphenylene oxide resin, polyester resin, alkyd resin, polyarylate resin, acrylic resin, methacrylic resin , phenoxy resin, etc. Among these, polystyrene resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polyarylate resins, phenol resins, and the like have excellent potential characteristics as photoreceptors. In addition, these resins may be used alone or as a copolymer.
A mixture of more than one species can be used. The amount of these binder resins added to the photoconductive compound is 0.2 to 10 times the weight ratio, preferably 0.
．． In the range of 5 to 5 times, if the amount is less than this, the photoconductive compound will precipitate in the photosensitive layer or on the surface, resulting in poor adhesion to the support, and if it is more than this, the sensitivity will decrease. Next, some of the film-forming binder resins used are rigid and weak in mechanical strength such as tension, bending, and compression, so it is necessary to add a substance that imparts plasticity to improve these properties. Become. These substances include phthalates (e.g. DO
P, DBP, DIDP, etc.), phosphoric acid esters (eg, TCP, TOP, etc.), sebacic acid esters, adipic acid esters, nitrile rubber, chlorinated hydrocarbons, and the like. When adding these plasticity imparting substances,
Since adding more than necessary will cause deterioration of potential characteristics, the proportion thereof is preferably 20% or less by weight based on the binder resin. Next, the sensitizing dyes added to the photosensitive layer include triphenylmethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, and rhodamine B10-damin 3B1 acridine dyes. Sansen dyes represented by DoB, acridine dyes represented by Acridine Orange 2G, Acridine Orange R1 Flaveosin, etc., thiazine dyes represented by methylene blue and methylene green, oxazine dyes represented by Kavli Blue, Melt Lab, etc. , and other cyanine dyes, styryl dyes, pyrylium salts, thiapyrylium salts, and squareium salt dyes. Photoconductive pigments that generate carriers with extremely high efficiency through light absorption in the photosensitive layer include phthalocyanine pigments such as metal-free phthalocyanine, phthalocyanine containing various metals or metal compounds, perylene imide, and perylene acid anhydride. These include perylene pigments such as quinacridone pigments, anthraquinone pigments, and azo pigments. Among these pigments, those using bisazo pigments, trisazo pigments, and phthalocyanine pigments, which have particularly high carrier generation efficiency, provide high sensitivity and provide excellent electronic photoreceptors. Furthermore, although the dye added to the photosensitive layer described above can be used alone as a carrier-generating substance, by coexisting with a pigment, carriers may be generated with even higher efficiency. Further inorganic photoconductive materials include selenium, selenium tellurium alloy, cadmium sulfide, zinc sulfide, amorphous silicon, and the like. In addition to the sensitizers mentioned above (so-called spectral sensitizers), it is also possible to add sensitizers (so-called chemical sensitizers) for the purpose of improving sensitivity. Examples of the chemical sensitizer include p-chlorophenol, m-chlorophenol, p-nitrophenol, 4
-Chloro-m-cresol, p-chlorobenzoylacetanilide, N,N=-diethylbarbital acid, 3-
(β-oxyethyl)-2-phenyliminothiazolidone, malonic acid dianilide, 3. 5. 3”, 5-
-tetrachloromalonic acid dianilide, α-naphthol,
p-nitrobenzoic acid. Further, it is also possible to add a certain type of electron-withdrawing compound as a sensitizer that forms a charge transfer complex with the styryl compound of the present invention and further increases the sensitizing effect. Examples of the electron-withdrawing substance include 1-chloroanthraquinone, 1-nitroanthraquinone, 2,3-dichloronaphthoquinone, 3,3-dinitrobenzophenone, 4
-Nitrobenzalmalonenitrile, phthalic anhydride, 3-
(α-cyano-p-nitrobenzal)phthalide, 2,4
．． Examples include 74-linitrofluorenone, 1-methyl-4-nitrofluorenone, and 2,7-sinitro-3,6-dimethylfluorenone. Other additives such as antioxidants and anti-curl agents may be added to the photoreceptor as required. The styryl compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives mentioned above depending on the form of the photoreceptor, the coating solution is applied onto the conductive support mentioned above, and then dried. A photoreceptor is manufactured. As coating solvents, halogenated hydrocarbons such as chloroform, dichloroethane, trichloroethane, and trichloroethylene, aromatic hydrocarbons such as benzene, toluene, and xylene, and solvents such as dioxane, tetrahydrofuran, methyl cellosolve, dimethyl cellosolve, and methyl cellosolve acetate may be used alone or Mixed solvent of two or more types or alcohols, acetonitrile, N, N if necessary
- Solvents such as dimethylformamide and methyl ethyl ketone may be added.

【Example】

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 1 part by weight of the bisazo pigment of formula (TV) and 1 part by weight of polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) were mixed with 100 parts by weight of tetrahydrofuran and dispersed together with glass peas in a paint conditioner device for 2 hours. The pigment dispersion thus obtained was applied with an applicator onto a polyester film coated with aluminum and dried, resulting in a film thickness of 0.
．． A film of 2 μm carrier-generating substance was formed. Next, a styryl compound represented by Exemplary Compound (3) was mixed with a polyarylate resin (Unitika U-Polymer) in a 1:1 ratio.
Mix at a weight ratio of 10% using dichloroethane as a solvent.
A solution was prepared, and this solution was applied onto the film of the carrier-generating substance using an applicator to form a carrier transport layer with a dry film thickness of 20 μm. The laminated electrophotographic photoreceptor thus prepared was evaluated for electrophotographic characteristics using an electrostatic recording test bag rJl (5P-428 manufactured by Kawaguchi Denki). Measurement conditions: applied voltage -6KV, static speed 3 (rotation speed mode of turntable on which sample is placed: 10)
m/min). As a result, the light half-reduction exposure to white light during charging is 2
．． It showed a very high sensitivity value of 0 lux·sec. Furthermore, the same device was used to evaluate repeated use. When the change in charging potential was determined after 103 repetitions,
In contrast to the initial potential of -960 V at the 1st run, the initial potential at the 103rd run was -950 V, indicating that the potential drop due to repetition was small and stable, indicating excellent characteristics. Examples 2 to 5 Laminated photoreceptors were prepared in the same manner as in Example 1, except that the styryl compounds shown in Table 1 were used in place of the styryl compounds used in Example 1, and the same measurement conditions as in Example 1 were carried out. The half-light exposure El/2 (lux seconds) and the initial potential Vo (volts) were measured, and the values are shown in Table 1. Furthermore, the initial potential Vo (volt) and half-reduced light exposure amount E1/ after repeating the same process 103 times with 1 cycle of charging and static neutralization (static neutralization light: 400 lux x 1 second irradiation with white light)
2 is shown in Table 1. (The following is a margin) Table 1 *: (lux φ seconds) Examples 6 to 10 A bisazo pigment (V) having the following structure was used as a charge generating substance. That is, 1 part by weight of this pigment and 1 part by weight of a polyester resin (Vylon 200 manufactured by Toyobo Co., Ltd.) were mixed with 100 parts by weight of tetrahydrofuran and dispersed together with glass peas in a paint conditioner device for 2 hours. The pigment dispersion thus obtained was applied onto the same support as in Example 1 using an applicator to form a carrier generation layer. The thickness of this thin film was about 0.2μ. Next, Example 1 was prepared using the exemplified compounds shown in Table 2.
A carrier transport layer was formed in the same manner as above to create a laminated photoreceptor. This photoreceptor was evaluated under the same measurement conditions as in Example 1. The results are shown in Table 2. (Margins below) Table 2 * (lux seconds) Comparative Example 1.2 A photoreceptor was prepared in the same manner as in Example 1, except that Comparative Compound 1.2 below was used in place of the compound used in Example 1. was created and its characteristics were evaluated. The results are shown in Table 3. Comparative Compound 2 Table 3 (v) Lower Giraffe)

【Effect of the invention】

As is clear from the above, according to the present invention, an electrophotographic photoreceptor having high sensitivity and high durability can be provided.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor containing a styryl compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, R^1, R^2, R^3, R^4, R^5, R
^6, R^7, and R^8 represent a hydrogen atom, an alkyl group that may have a substituent, an alkenyl group, an aralkyl group, or an aryl group. A represents a divalent aromatic ring or a heterocyclic residue which may have a substituent. Z^1 and Z^2 represent an atomic group required to form a saturated 5- to 8-membered ring together with the two carbon atoms of the indoline ring. )