JPS59170845A - Photosensitive body for electrophotography - Google Patents

Abstract

PURPOSE:To obtain a high sensitization effect and to improve sensitivity by adding a specific alkyl substd. tetracyanoquinodimethane to an org. photoconductive high polymer material. CONSTITUTION:The alkyl substd. tetracyanoquinodimethane expressed by the formula is added to an org. photoconductive high polymer material. Such alkyl substd. tetracyanoquinodimethane is dissolved together with the org. photoconductive high polymer in an org. solvent and the soln. is coated and dried, by which a photosensitive body is formed. The alkyl substd. tetracyanoquinodimethane has excellent compatibility with the photoconductive high polymer material and has an excellent sensitization effect. The photosensitive body having high sensitivity is obtainable from the same. Such photosensitive body is highly flexible and maintains the initial characteristics without change after electrostatic charging and exposing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor containing argyl-substituted tetracyanoquinodimethane in an organic photoconductive polymer material.

In general, an image forming method using an electrophotographic photoreceptor produced by providing a photoconductive photosensitive layer on a conductive support is called steron photography, and the image forming process consists of (1) dark The basic requirements of a photoreceptor in such an electrophotographic process are as follows: (2) formation of an electrostatic latent image by image island light, and (3) development with a toner7. Its characteristics are as follows5. 5. It can be charged to an appropriate potential in a dark place and can retain the charge.

(2) The surface potential is rapidly attenuated by the light irradiation IC,
No residual potential remains.

(3) It must have a wide range of spectral sensitivity in the visible light region.

0) High light resistance and durability.

Q) It must be non-toxic.

■) Processability (film formability, transparency, flexibility, mass productivity, etc.)
Be excellent.

Inorganic materials such as selenium, cadmium sulfide, and zinc oxide are known as photoconductive photosensitive materials for photoreceptors used in such electrophotographic processes, but they do not satisfy the various properties required for the photoreceptor. It is difficult to say that I am satisfied.

Furthermore, since the introduction of the electrophotographic process, various studies have been conducted on photoreceptors using organic photoconductive materials. For example, one of them is polyvinylcarbazole. Use of polyvinylcarbazole in electrophotographic processes, West German Patent Application Publication No. 10
No. 6,811 and U.S. Patent No. 3.037,86
It is shown in the specification of No. 1. However, since polyvinylcarbazole has a light absorption region on the shorter wavelength side than 360 mμ, its sensitivity to visible light is actually extremely low, and therefore requires sensitization.

Sensitization methods include spectral sensitization using sensitizing dyes and chemical sensitization using charge transfer complex formation using a substance with strong electron acceptor (acceptor). As dye sensitization for polyvinylcarbazole, for example, sensitization using a biryllium salt dye is disclosed in Japanese Patent Publication No. 48-25658. However, sensitization using dyes does not have sufficient sensitivity or durability after repeated use. For chemical sensitization by charge transfer complex formation, for example, a photoreceptor using a charge transfer complex with polyvinylcarbazole (!:2,4,7-dolinitroneluorenone) was disclosed in West German Patent Application Publication No. 1,572. , 347 and U.S. Patent No. 3
, 484,237.

R,M+SchMffsrt: r IBM
Journal of Research and De
velopment j Volume 15, No. 1 (1971
According to 2007), pp. 75-89, many substances other than 2°4.7-) linitrofluorenone have poor compatibility with polyvinylcarbazole and have a detrimental effect on photosensitivity at large concentrations. It is reported that 2.4.7-) Rinitrofluorenone is effective as a sensitizer for polyvinylcarbazole, but it is necessary to use it in an equimolar amount relative to the constituent repeating units of polyvinylcarbazole, that is, a large amount of 163% by weight. However, 2,4,7-dolinitrofluorenone is relatively expensive and has the drawbacks of high physiological activity.

The present inventor is currently researching various electron-accepting substances (acceptors) capable of forming charge transfer complexes such as organic photoconductive polymers, such as polyvinylcarbazole, and found that the following general formula [ID, (formula In the middle, R1, 1 and 2 are times or different,
Represents hydrogen, a linear or branched alkyl group having 1 to 7 carbon atoms, a cyclohexyl group, or a cyclo\xylmethyl group. However, the alkyl-substituted tetracyanoquinodimethane represented by 2) (except when R1 and R2 are both water resistant) has a large sensitizing effect on photopolymer 2, and can be used to produce extremely high-sensitivity photoreceptors. I found that I can give.

It was reported by Seiko Oka and colleagues that unsubstituted tetracyanoquinodimethane forms a charge transfer complex with polyvinylcarbazole and enhances the sensitizing effect. (1964), pp. 19-25. However, unsubstituted de(・racyanoquinodimethane) has poor compatibility with polyvinylcarbazole and cannot be said to have a sufficient sensitizing effect.
In the electron-accepting substance (acceptor) that forms a charge transfer complex with Dozu, an electron-withdrawing substituent is bonded,
In this case, the electron-accepting property of the compound increases (1), making it easier to form a charge transfer complex. On the other hand, when an electron-donating substituent is bonded to an acceptor, the electron-accepting property of the acceptor decreases, making it difficult to form a charge transfer complex.
hang-Transfer Complexes
j (peoplecademie Press, Londo
n and New York + 1969), 20
It is shown on pages 1-2O5. Therefore, compared to tetracyanoquinodimethane which does not have an alkyl group, the alkyl-substituted tetracyanoquinodimethane of the present invention, which has an alkyl group as an electron-donating substituent, can be used in a photoconductive polymer material. It is estimated that it becomes difficult to form a charge transfer complex with the donor component. However, according to the research of the present inventors, alkyl-substituted tetracyanoquinodimethane has extremely good compatibility with photoconductive polymeric substances at 1 to 1 compared to tetracyano--'nodimethane, which does not have a monomer group. However, the sensitizing effect is significantly lower than that of the conventional photoreceptor, and it becomes clear that the effect of increasing the sensitivity of the photoreceptor is 9, which is completely surprising.

The present invention was completed based on this knowledge,
The object of the present invention is to provide a highly sensitive electrophotographic photoreceptor comprising an organic photoconductive polymer material containing an alkyl-substituted tetracyanoquinodimethane substituted by the general formula (1).

The a/1kyl group represented by R1 and R2 of the general formula CI) is methyl, edyl, proyl, isopropyl, butyl, isobutyl, 1lee-butyl, tert
-butyl, n-amyl, isoamyl, 8ec-amyl AX
tert-amyl, D-hexyl, cyclohexyl A-,
Examples include cyclohexylmethyl.

Next, representative compounds of alkyl-substituted tetracyanoquinodimethane used in the electrophotographic photoreceptor of the present invention will be illustrated.

Exemplary compound (1) 2,5-diethyl-7,7°8.8-
Exemplary compound of detracyanoquinodimethane (212,5-di-n-propyl-7,7,
8,8-tetracyanoquinodimethane Exemplary Compound (3) 2-h-hexylfu, 7°8.8-
Tetracyanoquinodimethane exemplary compound (4) 2-cyclohexylmethyl-7,7,
8,8-Tetracyanoquinodimethane The alkyl-substituted tetracyanoquinodimethane of the present invention can be easily synthesized as follows. That is,
2-methyA--7,7,8,8-tetracyanoquinodimethane, 2゜5-dimethyl-7,7,8,8-tetracyanoquinodimethane, 2,5-dienal-797,8, 8-
Tetracyanoquinodi, methane (exemplified compound (11), 2
J, R9Anderse for the synthesis of ,5-diisopropyl-7゜7.8.8-tetracyanoquinodimethane.
n et al.: J, Chem, Soc.

Perkim l, (1979), 3095-30
98 negative and R, C, Wheland et al.: J, O
rg, Charn,.

Volume 40, No. 21, (1975), 3101-31
It is reported on page 09. By a method similar to this, alkyl-substituted tetracyanoquinodimethane can be synthesized according to the steps shown in the following formula.

Cl) [l) CIV) [V:]
CI) (wherein R1 and R2 have the above meanings), i.e.
Alkyl-substituted hydroquinone [1] is completely hydrogenated under hydrogen pressure using palladium-alumina as a catalyst to obtain alkyl-substituted cyclohexane-1,4-diol 1].

This is oxidized with sulfuric acid-chromic acid to give alkyl-substituted cyclohexadione CIV), and then malonitrile is condensed using β-alanine as a catalyst to produce alkyl-substituted bisdicyanomethylene cyclohexane [■]. After adding bromine to this compound [■], pyridine is applied to dehydroborate the compound to obtain the desired argyl-substituted tetracyanoquinodimethane [1].

The organic photoconductive polymer substance used in the present invention includes a donor component that forms a charge transfer complex using an alkyl-substituted tetracyanoquinodimethane represented by the general formula [l] as an acceptor, such as carbazole, naphthalene, It is possible to use a polymeric substance containing a component such as anthracene, pyrene, perylene, and a halogen or lower alkyl substituted product of anthracene and a substituent. For example, vinyl polymers such as polyvinyl A/carbazole, polyvinylnaphthalene, polyvinylanthracene, polyvinylpyrene, and polyvinylperylene; vinyl ether polymers such as polycarbanyl ether vinyl ether, polyanthryl methyl vinyl ether, and polyvinyl methyl vinyl ether nato;
Examples include epoxy resins such as polyglycidyl carbazole; furthermore, polymers such as polyacrylic esters and polymethacrylic esters containing the above donor component as a substituent, or copolymers thereof. Among these, preferred are poly-N-vinylcarbazole, if
Examples include poly-N-vinylcarbazole copolymers, which are copolymers of c, N-vinylcarbazole and styrene, acrylonitrile, methacrylonitrile, vinyl chloride, methyl acrylate, methyl methacrylate, and the like.

Electrophotographic photoreceptor H1 of the present invention, for example, a conductive support such as a metal plate such as aluminum, a metal foil, a glass film deposited with a metal such as aluminum, or paper subjected to conductive treatment, It is produced by dissolving the above-mentioned organic photoconductive polymer material and alkyl-substituted tetracyanoquinodimethane in an appropriate organic solvent, applying the solution, and drying it. .

The mixing ratio of the organic photoconductive polymer substance and the alkyl-substituted tetracyanoquinodimethane is 0.001 to 2.0 per mole of the structural unit containing the donor component in the organic photoconductive polymer.
MoA is preferably 0.001 to 1.1 moles. o, o
If the amount is less than oi mole, the desired effect cannot be obtained,
Further, an amount exceeding 2.0 mol is undesirable because it causes a decrease in v, Il & band tft on the surface of the light body, an increase in dark decay, a decrease in mechanical strength, etc.

Examples of the organic solvent for dissolving the organic photoconductive polymer substance and the alkyl-substituted tetracyanoquinodimethane include benzene or toluene, xylene, substituted benzenes such as chlorobensenato, ketones such as acetone, methyl ethyl ketone, and diethyl quatone, and ethyl acetate. ester a
, [halides such as methylene chloride, chloroform, dichloroethane, and mixtures thereof can be used. In these solvents, film-forming binders such as polynisder resin, polyvinyl chloride/l-
Resin, acrylic resin, methacrylic resin, polystyrene resin, polycarbonate resin, etc. are used. Coating onto the conductive support can be done by a conventional method, such as a doctorb 1/-
This can be done using a wire burner, etc. At this time, if necessary, an adhesive layer made of, for example, casein, polyvinyl alcohol, polyvinylpyrendone, polyamide, etc. may be provided between the conductive support and the photosensitive layer. The thickness of the photosensitive layer is 3 to 50μ, preferably 5 to 20μ
μ.

As described above, the electrophotographic photoreceptor of the present invention obtained in steps 1 to 1 has excellent features such as extremely high sensitivity, high flexibility, and properties that do not change due to charging exposure.

Next, the present invention will be explained with reference to synthesis examples, examples, and comparative examples of seven representative compounds used in the present invention, but the embodiments of the present invention are not limited thereby.

Synthesis Example 1 (Synthesis of 2,5-di-n-propyl-1,4-cyclo△, GI) 2.5-di-n-propylhydroquinone 23r15%
Palladium-alumina 2, isopropanol 100-
was placed in a 300-degree autoclave and pressurized with hydrogen (20K).
2/c1n2) at 150° C., and the reaction was carried out until hydrogen absorption stopped. After 1 hour, the mixture was filtered and the furnace liquid was concentrated under reduced pressure to obtain crude 2,5-di-n-propyl-1,4-cyclobexanediol 24y. Add this to acetone 150
Dissolve 17.8 f of chromic anhydride in 15 cc of sulfuric acid.
．． 2 m7! Add a solution dissolved in 25.4 d of water and 1
- The reaction was stirred at room temperature for 4 hours. Acetone was distilled off under reduced pressure,
The residue was extracted with benzene, and the benzene extract was washed with water and concentrated under reduced pressure to obtain crude crystals 21.4r.

This was recrystallized from hexane to obtain 15.91 g of 2,5-n-propyl-1,4-cyclohegizadione. Melting point: 84°C, theoretical yield: 69.5%, Synthesis Example 2 (Synthesis of 2-n-hexyl-1,4-cyclohexidione) 2,5-di-n-butylhydroquinone used in Synthesis Example 1 2-n-hexylhydroquinone instead of 22.6? Using fCnikat,1, 2-n-hexyl-1,4-cycloA-yasion 19.1y was obtained in the same manner as in Synthesis Example 1. Melting point: 49°C, νII temperature: 83.5
%.

Synthesis Example 3 (Synthesis of 2-cyclohexylmethyl-1,4-cyclohexadidine) 2-benzylhydride + 1 quinone 23 in place of 2,5-di-n-furobylhydroquinone used in Synthesis Example 1
When using 5', 2-cyclohexylmethy3-1,4-dicyclohecadione 3 was synthesized using Synthesis Example 1 and 1=1.
-5.8r was obtained. Melting point 88℃, theoretical yield 65.0%3
゜Synthesis Example 4 (Synthesis of 1,4-bisdicyanomethylene-2,5-di-n-probylcyclohexane) 2,5- obtained in Synthesis Example 1
Di-n-propyl-1,4-cyclohexene 9.8r
A mixture of 6.61 parts of malonitrile, 0.21 parts of β-alanine, and 15 parts of water was reacted at 95 to 103°C between i 0 and gi. After cooling, 1 water and ether were added and stirred, and the resulting crystals were This was recrystallized from acetonitrile to obtain 1,4-bisdicyanomethylene-2,5-di-n-
Propylcyclohexane 9.6i was obtained. Melting point 241℃
, theoretical yield 66.0%.

Synthesis Example 5 (Synthesis of l,4-bisdicyanomethylene-2-n-hexylcyclohexane) Synthesis Example 4 2,5-di-n-zorobyl- using Ni-C
1.4 was prepared in the same manner as in Synthesis Example 4, except that 9.82 of 2-n-hexyl-1,4-cyclohexadione obtained in Synthesis Example 2 was used in place of 1,4-cyclohexadione.
-Bisdicyanomethylene-2-n-hexylcyclohexane 1o51 was obtained. Melting point: 87°C, theoretical yield: 72%.

Synthesis Example 6 (Synthesis of 1,4-bisdicyanomethylene-2-cyclohexylmethylcyclohexane) In place of 2,5-di-n-propyl-1,4-cyclohexyldione used in Synthesis Example 4, Synthesis Example 3 Synthesis Example 4 was repeated, except that 2-cyclohexylmethyl-1,4-cyclohexadione 10.4r obtained by I got it. Melting point: 154°C, theoretical yield: 70.0%
.

Synthesis Example 7 (2,5-Di-n-7,7,8,8-putracyanoginodimethane: Synthesis of Exemplary Compound (2)) 1,4-bisdicyanomethylene-2,5 obtained in Synthesis Example 4 -G-n-
Dissolve 62 of norobylcyclohexane in 80 of acetonitrile and prepare 20 of acetonitrile containing 6.42 of bromine.
was added dropwise to the mixture at room temperature, and then 10-mL of acetonitrile containing 6.42% of pyridine was slowly added to the mixture while cooling with water. After stirring at room temperature for 18 hours, 150 ml of cold water was gradually added and stirred for 3 hours. The formed crystals were separated, washed with water and ether, and then recrystallized from acetonitrile to obtain 2.5
-di-n-propyl-7,7,8,8-detracyclinoquinodimethane 4.11 was obtained.

Melting point: 155°C, theoretical yield: 71.2%.

Synthesis Example 8 (2-n-hexylfluf, 7.8.8-detracyanoquinodimethane: Synthesis of Exemplary Compound (3)) 1,4-Hisdicyanomethylene-2,5- used in Synthesis Example 7 Instead of di-n-propylcyclohexane,
1,4-bisdicyanomethylene- obtained in Synthesis Example 5
2-n-hexylcyclohexane 5.81 was prepared in the same manner as in Synthesis Example 7, and 2-n-hexylcyclohexane 7.81 was used.
3.61 of 7.8.8-tetracyanoquinodimethane was obtained. Melting point: 117°C, theoretical yield: 62.8%.

Synthesis Example 9 (2-cyclohexyA/methyl-7,7,8,8-detracyanoquinodimethane: synthesis of exemplified compound (4)) 1,4-bisdicyanomethylene-2, used in Synthesis Example 7 Instead of 5-di-n-propylcyclohexane,
*i, 4-bisdicyanomethylene- obtained according to Synthesis Example 6
h using 6t of 2-cyclohexylmethylcyclohexane
-Other than that, 1.5f of 2-cyclohexylme Bruch and 7,8.8-tetracyanoquinodimethane were obtained in the same manner as in Synthesis Example 7. Melting point: 137°C, theoretical yield: 25.4%
.

Example J Prepare 19.3 f of a 10% chlorobenzene solution of two poly-N-vinyl carbazoles, and add 2,
23.6■ and 236■ of 5-diethyl-7,7,8,8-tetracyanoquinodimethane (exemplified compound (1))
were dissolved to prepare solutions with concentrations of 0.01 mol and 0.1 mol per mol of donor component t, ie carbacy A-. Each of these was applied using a doctor blade onto a polyester film on which aluminum was vapor-deposited, and dried at 45° C. to produce a photoreceptor having a thickness of 15 μm. This photoreceptor was charged by corona discharge of 16 KV for 30 seconds using a tersitable type surface potential measuring device, and then left in a dark place for 10 seconds. Surface chamber 1 at this time
The rank is vo. This was irradiated with tungsten light, and the exposure amount until the 11th position on the surface became 1/2 of Vo, that is, the half-reduced exposure amount E1/2 was determined. As a result, the results shown in Table 1 were obtained.

Example 2 2,5-diethyl-7゜7.8.8- used in Example 1
Instead of tetracyanoquinodimethane, 2,5-di-n-
28.8 wq and 288q of propyl-7,7°8.8-tetracyanoquinodimethane (exemplified compound (2))
Table 1 shows the results obtained using Example 1 and 1h1.

Example 3 2,5-diethyl-7゜7.8.8- used in Example 1
In place of tetracyanoquinodimethane, 28.8■ and 288■ of 2-n-hexylf, 7.8.8-tetracyanoquinodimethane (exemplified compound (3)) were used, and the same procedure as in Example 1 was carried out. Table 1 shows the results obtained in the same manner.

Example 4 2,5-diethyl-7゜7.8.8- used in Example 1
30, 4 and 304 of 2-cyclohexylmethane -7+ 7 +8.8-tetracyanoquinodimethane (exemplified compound (4)) in place of tetracyanoquinodimethane
Using M1i, the results obtained in the same manner as in Example 1 were
Shown in the table.

Comparative Example 1 Prepare 19.3 f of a 10% chlorobenzene solution of two poly-N-vinylcarbazoles, and add 7
．． 7. Adding 1.2 rq and 4.3 cape of 8-tetracyanoquinodimethane (hereinafter referred to as comparative compound),
Solutions of 0.006 mol and 0.021 mol were prepared for 1 mol of donor component carbazole. The former was completely dissolved, but the latter was not sufficiently dissolved and some insoluble matter was observed. The results obtained using these in the same manner as in Example 1 were
Shown in the table.

Examples 5 to 8 The photosensitive materials produced in Examples 1 to 4 were subjected to -1 6KV corona discharge using the test method shown in Example 1.
-5KV corona discharge is replaced with tl or 12
The results shown in the table were obtained.

Comparative Example 2 The photosensitive material prepared in Comparative Example 1 (12, however, the material containing 0.021 mol% of the comparative compound had poor solubility;
Since it was unsuitable for use as a product, K was removed and tested in the same manner as in Examples 5 to 8. The result is the second
Shown in the table.

Below margin

Claims (1)

[Scope of Claims] The organic photoconductive polymer substance has the following general formula [1], (wherein R1 and R2 are the same or different, hydrogen or having 1 to 1 carbon atoms)
It shows seven linear or branched argyl groups, cyclohexyl groups or cyclohexylmethyl groups. However, R
1. An electrophotographic photoreceptor comprising an alkyl-substituted tetracyanoquinodimethane represented by the formula (except when 1 and R2 are both hydrogen).