JPS63132247A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To afford spectral sensitivity in the range from visible region to near infrared region, high sensitivity and superior electric characteristics to an electrophotographic sensitive body by providing a photosensitive layer contg. a specified asymmetric squarylium compd. to the layer. CONSTITUTION:A photosensitive layer 4 comprising a layer-built body constituted of a charge generating layer 2 contg. an asymmetric squarylium compd. expressed by the formula and a charge transfer layer 3 contg. a charge transfer material is formed on an electroconductive substrate 1. In the formula, each R1, R2 is alkyl, phenyl group; each R3-R5 is H atom, OH group, etc.; R6 is alkyl group; n is zero or an integer 1-5. The charge generating layer may be formed of the squarylium compd. alone, but it may be formed also by the use of finder resin in combination. In the latter case, pref. proportion of the squarylium compd. to the binder resin is 20-70wt%. By this constitution, the electrophotographic sensitive body can acquire spectral sensitivity in the range from visible region to near infrared region, high sensitivity and superior electric characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to electrophotographic photoreceptors used in electrophotographic processes. More specifically, the present invention relates to an electrophotographic photoreceptor containing a novel square aryllium compound in a photoconductive layer.

Conventional technology Conventionally, undefeated photosensitive materials such as amorphous selenium, selenium alloys, cadmium sulfide, and zinc oxide, and organic photosensitive materials such as polyvinyl carbazole and polyvinyl carbazole derivatives have been widely known as electrophotographic photoreceptors. .

It is well known that amorphous selenium or selenium alloy has extremely excellent properties as an electrophotographic photoreceptor and is used in practical use. However, its production requires a complicated step of vapor deposition, and the produced vapor-deposited film has the drawback of not being flexible. When zinc oxide is used, it is used as a dispersed photosensitive material in which zinc oxide is dispersed in a resin, but such a photosensitive material has a drawback in mechanical strength and cannot withstand repeated use as it is.

Polyvinylcarbazole, which is widely known as an organic photoconductive material, has excellent advantages in terms of transparency, film-forming properties, and flexibility, but polyvinylcarbazole itself does not have sensitivity in the visible light range. , cannot be put to practical use as it is, and therefore various sensitization methods have been proposed.

However, when polyvinylcarbazole is spectrally sensitized using a dye sensitizer, the spectral sensitivity range is extended to the visible light range, but it still does not have sufficient sensitivity as an electrophotographic photoreceptor and suffers from photofatigue. It has a serious drawback. or,
When chemically sensitized using an electron-accepting compound, a photoreceptor with sufficient sensitivity as an electrophotographic photoreceptor can be obtained, and some of them have been put into practical use. There are still some problems.

In recent years, many types of organic electrophotographic photoreceptors have been studied, and it has been reported that stacked photoreceptors in particular, which have a charge generation layer and a charge transport layer, have superior electrical properties compared to conventional photoreceptors. . Known charge generating materials used in these electrophotographic photoreceptors include bisazos, trisazos, phthalocyanines, pyryliums, square lyliums, and the like. Phthalocyanines, trisazo compounds, and squareylium compounds have been reported to have sensitivity from the visible region to the near-infrared region.
It is described in JP-A-9-105536 and JP-A-58-214'6.

Problems to be Solved by the Invention However, phthalocyanines have disadvantages in that their spectral sensitivity is biased toward long wavelengths and poor red color reproducibility, and trisazo compounds do not have excellent electrical properties and sufficient sensitivity. .

Furthermore, the square aryllium compound shown in JP-A No. 58-214162 does not have sufficient sensitivity, and the square aryllium compound shown in JP-A 49-105536 etc. has relatively high sensitivity. It has drawbacks in chargeability, dark decay, etc., and has not been able to achieve both high sensitivity and low dark decay.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an electrophotographic photoreceptor that has spectral sensitivity from the visible region to the near-infrared region, and has high sensitivity and excellent electrical properties.

Means for Solving the Problems The above objects of the present invention can be achieved by using an asymmetric square lylium compound represented by the following general formula (I) as a photosensitive material for an electrophotographic photoreceptor. Therefore, the electrophotographic photoreceptor of the present invention is characterized by having a photoreceptor containing an asymmetric square aryllium compound represented by the following general formula (I).

(In the formula, R and R2 each represent an alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group, and R3 is a hydrogen atom, a hydrogen atom, Represents a methyl group, trifluoromethyl group, halogen atom, carboxyl group, furkylcarbonylamino group, or alkylsulfonylamino group, R4 represents a hydrogen atom, a water group, or an alkyl group, and R5 represents a hydrogen atom or an alkyl group. , an alkoxycarbonyl group, or a substituted or unsubstituted carbamoyl group, R6 represents an alkyl group, and n represents an integer from O to 5.) Specific examples of the square lylium compound used in the electrophotographic photoreceptor of the present invention The following can be mentioned.

H3 These squarelylium compounds are produced by, for example, reacting squarium chloride and an aniline derivative represented by the general formula (n> (wherein R1-R3 have the same meanings as above) in a free-solat fluoride type reaction. The resulting cyclobutenedione derivative was hydrolyzed and heated in an organic solvent with an azulene derivative represented by general formula (III) (wherein R-R6 has the same meaning as above). , an example thereof is shown below.

(Synthesis example) Square phosphate chloride 7.59 (0,050 mol) and boron trifluoride ethyl ether forceps 6.5af2 (0
,050 mol) in 30 ml of methylene chloride, N,
N-dimethyl-m-fluoroaniline 3! M (0,
25 mol> and stirred at the lowest temperature for 16 hours to carry out the reaction. After the reaction was completed, the mixture was washed with dilute hydrochloric acid and then with water.
Perform separation and purification using column chromatography,
3-chloro-4-(4'-dimethylamine-2-fluorophenyl)-3-cyclobutene-1,2-dione
9. "NJ (yield 72%) was obtained.

Next, 60 d of acetic acid and 20 ml of water were added to 9.1 s (0,039 mol) of the obtained compound, and the mixture was heated under reflux for 1 hour. After cooling, the precipitate was filtered out and washed with water to give 3-( 4-dimethylamino-2-fluorophenyl)-4-hydroxy-3-cyclobutene-1,2-dione 8.5y(
A yield of 92%) was obtained.

Obtained 4-hydroxycyclobutene derivative 0.67g
(2,8 mmol) and 1-phenylcarbamoyl-2-
Hydroxyazulene 0.75Sl? (2.8 mmol) was suspended in 100 d of butanol and heated under reflux for 5 hours. The mixture was allowed to cool, and the precipitate was separated by filtration and washed with methanol and ether to obtain the exemplified compound \α11 1.16y (yield 86%).

Melting point: 291°C (decomposed) Infrared absorption spectrum: Figure 3 Elemental analysis: The relaxed square 1 thulium compound exemplified above as C29H21FN204 can also be synthesized in the same manner as above.

In the present invention, the square lium compound represented by the general formula (I>) is included in the photosensitive layer of the electrophotographic photoreceptor,
It is preferable to use it in an electrophotographic photoreceptor in which the photosensitive layer has a multiperipheral structure. That is, in an electrophotographic photoreceptor including a photosensitive layer with a two-layer structure consisting of a charge generation layer and a charge transport layer,
By providing a charge generation layer containing a square aryllium pigment and a known charge transport layer, it is possible to obtain an electrophotographic photoreceptor that is highly sensitive and has improved electrical properties such as chargeability and dark decay.

A case where the electrophotographic photoreceptor of the present invention has a photosensitive layer having the above-mentioned two-layer structure will be explained with reference to the drawings. As shown in FIGS. 1 and 2, a square lium compound is A photosensitive layer 4 is provided, which is a laminate of a charge generation layer 2 containing a charge transport material and a charge transport layer 3 containing a charge transport substance. The stacking order of the charge generation layer 2 and the charge transport layer 3 is arbitrary.

In this case, a protective layer may be provided on the photosensitive layer 4, or an intermediate layer may be provided between the photosensitive layer 4 and the conductive support 1.

The charge generation layer may be formed of the square aryllium compound alone, but it can also be formed using the square aryllium compound in combination with a binder resin.

In the latter case, the proportion of the squareylium compound to the binder resin is from 10% to 90% by weight, preferably from 20% to 70% by weight.

When using a binder resin, the binder resin itself may or may not have photoconductivity. Examples of the photoconductive binder resin include photoconductive polymers such as polyvinylcarbazole, polyvinylcarbazole derivatives, polyvinylnaphthalene, polyvinylanthracene, and polyvinylpyrene;
Or other organic matrix materials having charge transport ability can be mentioned.

Furthermore, as the binder resin that does not have photoconductivity, a known insulating resin can be used.

Examples of these known insulating resins include polystyrene, polyester, polyvinyltoluene, polyvinylanisole, polychlorostyrene, polyvinyl butyral, polyvinyl acetate, polyvinyl butyl methacrylate, copolystyrene-butadiene, polysulfone, copolystyrene-methyl methacrylate, and polycarbonate. It will be done.

At this time, in order to further improve the mechanical strength of the resulting electrophotographic photoreceptor, a plasticizer can be used in the same manner as in general polymeric materials. As the plasticizer, for example, chlorinated paraffin, chlorinated biphenyl, phosphate plasticizer, phthalate plasticizer, etc. can be used, and it is added in an amount of 0 to 10% by weight to the binder resin to improve the sensitivity of the electrophotographic photoreceptor. It is possible to further improve its mechanical strength without deteriorating its electrical properties.

The thickness of the charge generation layer is 0.05 to 3μ, preferably 0.1μ.
~1μ.

The charge generation layer is formed by a well-known method. That is, when forming a charge generation layer using a square aryllium compound alone without using a binder resin, solvent coating and vacuum evaporation methods can be used.

Furthermore, when a binder resin is used in combination, the square aryllium compound is pulverized and then dispersed in the binder resin. As the pulverization method, known methods such as SPEX MILL, ball mill, RED DEVIL (trade name), etc. can be used.

The binder resin in which the squareylium compound is dispersed is coated on the charge transport layer or the conductive support. Coating methods include a dipping method, a spray method, a bar coater method, and an applicator method, and a good charge generation layer can be formed by any of these methods.

On the other hand, the charge transport layer includes N-methyl-N-phenylhydrazino-3-methylidene-9-ethyl levazole, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α- Hydrazones such as naphthyl-N-phenylhydrazone, 1-phenyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, 1-(quinolyl(2))-3-(p-diethylaminostyryl) )-pyrazolines such as 5-(p-diethylaminophenyl)pyrazoline, oxazole compounds such as 2-(p-diethylaminostyryl)-6-dinithylaminobenzoxazole, bis(4-diethylamino-2-methylphenyl)- Triarylmethane compounds such as phenylmethane, N,N--diphenyl-N
, N-1bis=(3-methylphenyl)-(I,1'-
Biphenyl)-4,4-diamine or other diamine compounds contained in the binder resin, or poly-
Photoconductive polymers such as N-vinylcarbazole and polyvinylanthracene are used.

Further, as the conductive support, metal, paper treated with conductivity, a polymer film having a conductive layer, glass, etc. can be used.

Example Next, the present invention will be explained by examples.

Example 1 To 1 part by weight of Exemplary Compounds No. 2, 1 part by weight of polyester resin (DuPont, Adhesive 49000) and Tetrahydroflango O-type assembly were added, and the resulting dispersion was ground and mixed in a ball mill for 4 hours using a bar coater. The mixture was coated on a polyester film [Metal Me (registered trademark) manufactured by Toshi Co., Ltd.] on which aluminum had been vapor-deposited, and dried at 70° C. for 5 hours to form a charge generation layer with a thickness of 1 μm.

On this charge generation layer, N,N''-diphenyl-N,N-
1 part by weight of 1-bis-(3-methylphenyl)-[1゜1'-biphenyl]-4,4''-diamine, 1 part by weight of polycarbonate resin (manufactured by Ondai, Panlite (registered trademark)), and tetrahydrarot. A homogeneous solution consisting of 10 parts by weight of furan was applied using an applicator and dried at 70'C for 16 hours to form a charge transport layer with a thickness of 22 μm, thereby producing an electrophotographic photoreceptor.

Next, using an electrostatic copying sleep test device (manufactured by Kawaguchi Electric, Electrostatic Paper Analyzer 5P-428), after being negatively charged by applying corona discharge of -6 kV, it was left in a dark place for 2 seconds, and then Using a tungsten lamp, apply a light source to the photosensitive layer so that the surface illuminance is 10 lux, and set the exposure amount E1/2 so that the surface potential becomes 1/2 of the surface potential VD after being left in the dark. The results were as follows: initial charging potential Vo = -900V, potential after being left in the dark for 2 seconds VDDP = -880V, E 1 /2 =
The residual potential was 4.2 lux·sec, Rp=OV.

In addition, the following measurements were performed to demonstrate that the material has extremely high sensitivity to long-wavelength light. After charging the above photoreceptor by performing corona discharge in a dark place, it was divided into 1 μW/soonm using a monochromator.
The photoreceptor was irradiated with cti monochromatic light. Then, the time required for the surface potential to decrease to 1/2 was measured, and the exposure amount was determined. The result was 19.2 erg/c/i.

Examples 2 to 8 In Example 1, as shown in Table 1, exemplified compounds NQ5.6.7.11.12.13 and 16 (respectively Examples 2 to An electrophotographic photoreceptor was prepared in the same manner as in Example 1 except that Example 8) was used, and its characteristics were evaluated. The results obtained are shown in Table 1.

Table 1 Effects of the Invention The electrophotographic photoreceptor of the present invention has a photosensitive layer containing a square aryllium compound that has spectral sensitivity from the visible region to the near-infrared region and has high sensitivity and excellent electrical properties. It has excellent electrical properties such as chargeability and dark decay, and can be widely used not only in copying machines but also in semiconductor laser printers.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing cross-sectional views of the electrophotographic photoreceptor of the present invention, and FIG. 3 shows an infrared absorption spectrum of an example of the square aryllium compound used in the present invention. . DESCRIPTION OF SYMBOLS 1... Conductive support, 2... Charge generation layer, 3...
Charge transport layer, 4... photosensitive layer.

Claims (1)

[Claims] General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 and R_2 each have 1 to 20 carbon atoms.
represents an alkyl group, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted benzyl group, and R_3 is
Hydrogen atom, hydroxyl group, methyl group, trifluoromethyl group,
Represents a halogen atom, carboxyl group, alkylcarbonylamino group or alkylsulfonylamino group, R_
4 represents a hydrogen atom, a hydroxyl group, or an alkyl group, and R_
5 represents a hydrogen atom, an alkyl group, an alkoxycarbonyl group, or a substituted or unsubstituted carbamoyl group, and R_
6 represents an alkyl group, and n represents an integer from 0 to 5. ) An electrophotographic photoreceptor comprising a photosensitive layer containing an asymmetric squarerium compound represented by: (2) The squarerium compound has the above general formula (I)
, R_1 and R_2 each represent a lower alkyl group or a benzyl group, R_3 represents a hydrogen atom, a hydroxyl group, a methyl group, or a halogen atom, R_4 represents a hydrogen atom or a hydroxyl group, R_5 represents a hydrogen atom, a lower alkyl group, The electrophotographic photoreceptor according to claim 1, wherein n represents an alkoxycarbonyl group or a phenylcarbamoyl group and n represents 0.