JPH01200263A - electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE:To obtain characteristics which are always stable to heat and light and are excellent in carrier transferability and to obtain an electrophotographic sensitive body having high sensitivity and excellent electrostatic chargeability by incorporating the tetrahydroimidazole compd. expressed by the general formula into a photosensitive layer to be formed on a conductive base of the photosensitive body. CONSTITUTION:The photosensitive layer is formed on the conductive base of the electrophotographic sensitive body and the tetrahydroimidazole compd. expressed by the general formula is incorporated into the photosensitive layer. In the formula, R, R' denote an aralkyl group which may contain a substituent, aryl group which may contain a substituent, alkyl group; (a), a', a'' denote hydrogen, lower alkyl group, lower alkoxy group. The photosensitive body having the high sensitivity, the small residual potential and the excellent durability to oxidation, etc., is obtd. by the excellent characteristics of the tetrahydroimidazole compd. that said compd. is always stable to heat and light and has the excellent carrier transferability.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Industrial Field of Application The present invention relates to an electrophotographic photoreceptor, and more particularly, to a photoreceptor formed on a conductive support and containing a novel tetrahydroimidazole compound in its photosensitive layer. The present invention relates to an electrophotographic photoreceptor.

More specifically, the present invention relates to a highly durable electrophotographic photoreceptor with high sensitivity, high charging ability, and excellent repeat stability.

(B) Prior art Conventionally, in electrophotographic technology, photosensitive J
Inorganic materials such as selenium, cadmium sulfide, amorphous silicon, and zinc oxide are widely used for @, but in recent years, many organic photoconductive materials have been polished for use as all-electrophotographic photoreceptors. There is.

Here, the basic characteristics required for an electrophotographic photoreceptor include: (1) High chargeability due to corona discharge in a dark place. (2) One charge due to the n liter corona charge has little attenuation in the dark. (3) Charges are quickly dissipated by light irradiation. (4) There is little residual charge after the original irradiation. (5) Low light fatigue properties. (6) Repeatability characteristics should be stable and durable. etc.

Conventional inorganic electrophotographic photoreceptors such as selenium and cadmium sulfide have all the requirements as photoreceptors in terms of basic properties, but they have manufacturing problems such as high toxicity and difficult film formation. The disadvantages such as lack of flexibility and high manufacturing costs are completely ignored, and in the future, due to the depletion of resources, the use of inorganic materials whose production is limited will be even more important due to sensitivity. Also in terms of pollution, it is desired to use photoreceptors made of organic materials rather than inorganic materials.

However, in view of these points, research on electrophotographic photoconductors made of organic materials has been actively conducted in recent years, and photoreceptors for electrophotography using various organic materials have been proposed and put into practical use. Some have.

Generally speaking, organic ones have better transparency than inorganic ones, and vj! It has advantages such as easy film formation at t, both positive and negative imperial growth properties, and easy production of photoreceptors.

By the way, typical examples of organic electrophotographic photoreceptors that have been proposed so far include polyvinylcarbazole and its derivatives, but these do not necessarily have film properties, flexibility, solubility, Adhesive properties are sufficient, and polyvinylcarbazole is sensitized with pyridium salt dye (Japanese Patent Publication No. 48-25658), and polyvinylcarbazole and 2.4°7-dolinitrofluorenone are sensitized ( Although improvements such as U.S. Pat. I haven't done it.

((2) Purpose of the Invention The purpose of the present invention is to provide NFC tetrahydroimidazolization @r which is stable to heat and light and has excellent carrier transfer ability.
The object of the present invention is to provide a complete photographic photoreceptor containing all materials.

Another object of the present invention is to provide a high-sensitivity, low-residual material, small change in electrophotographic properties and image properties even when used repeatedly, and excellent durability against oxidation and other oxidation. Our goal is to provide a full range of photographic photoreceptors.

Yet another object of the invention is to provide a wide range of carrier generating materials (
The object of the present invention is to provide an electrophotographic photoreceptor that can exhibit effective characteristics even with the combination of azo pigments and phthalocyanine pigments.

(D) Structure of the Invention The present inventors conducted research on photoconductive substances having high sensitivity and high durability, and as a result, they found that a tetrahydroimidazole compound represented by the following general formula (I) is effective, and the present invention reached.

几B/ (In the formula, 几 and B' are an aralkyl group that may contain a substituent, an aryl group that may contain a substituent, or an alkyl group, and a, m', and m' are hydrogen, a lower alkyl group, and a lower alkoxy The tetrahydroimidazole compound of general formula (I) according to the present invention is usually synthesized by the following synthesis process.

几几′ (几, 几′, 11.Il, I in the above reaction formula have the same meanings as above.) The above reaction? Specifically, 1 mole of N-f-substituted -N/-substituted ethylenediamine and 1 mole of N,N-diphenylaminobenzaldehyde derivative are combined by heating in a solvent inert to the entire reaction in the presence of an acid catalyst if necessary. Let's do it
Ru.

The solvents used include alcohols (ethanol, amyl alcohol, etc.), trough-like ethers (dioxane, etc.), esters (ethyl acetate, etc.), aromatic hydrocarbons (benzene, chlorobenzene, etc.), and acids. As the catalyst, acetic acid, P-)luenesulfonic acid, hydrochloric acid, etc. are used.

Further, the heating time may be relatively short, within 2 minutes to 1 hour.

Specific examples of the tetrahydroimidazole compound useful in the present invention represented by the general formula (I) include those having the following structural formula.

The electrophotographic photoreceptor according to the present invention can be obtained by containing one kind of the above-mentioned compounds or ZflI or more compounds. Furthermore, it is possible to further improve the electrophotographic properties (e.g., photoresistivity, repeatability) by cometalizing with other organic additives, especially hydrazone compounds.0 As an effective hydrazone compound , N-ethylcarbazole-3-aldehyde-diphenylhydrazone, dibenzylaminobenzaldehyde-diphenylhydrazone, 3,3-di(
Examples include (P-diethylaminophenyl)-2-propenal-diphenylhydrazone. Various methods are known for using tetrahydroimidazole compounds as all-electrophotographic photoreceptors. And infection charge? If necessary, a photoreceptor or a carrier generation layer with extremely high charge carrier generation efficiency is prepared by adding a chemical sensitizer or an electron-withdrawing compound and dissolving or dispersing it in a binder, and then providing the following on a conductive support. The present tetrahydroimidazole compound is applied, if necessary, to a carrier generating layer provided as a whole dye or pigment on a conductive support in the form of a product structure consisting of a carrier transfer layer and a Lewis acid compound or an electron-withdrawing compound. There are photoreceptors in which the carrier is dissolved or dispersed in a binder resin as an additive, and a photoreceptor is provided as a carrier transfer layer, but it can be applied in either case.

When producing a photoreceptor using the tetrahydroimidazole compound of the present invention, the film is placed on a support such as a metal cylinder such as aluminum, a metal plate, a film deposited with aluminum or the like, or paper coated with conductive metal. Forming a film with the help of a forming binder.

Various types of film-forming binders can be used depending on the field of use.

That is, in the field of photoreceptors for copying, polystyrene resin,
Preferred are polyvinyl acetal resin, polysulfone resin, polycarbonate resin, acid vinylcrotonic acid copolymer resin, polyphenylene oxide resin, polyester resin, alkyd resin, polyarylate resin, and the like.

These can be used alone or as a co-monomer polymer in one or two pieces.
It can be used in combination with more than one. Among them, resins such as noryl, polyphenylene oxide, polycarbonate, and polyarylate resins have a binder having a volume resistivity of 10,130 or more, which has excellent film properties, electrophotographic properties, etc.

Further, the amount of the binder added to the organic photoconductor is 0.2 to 20 times the weight ratio, preferably 0.5 to 5 times, and when the amount is 0.5 or less, the organic photoconductor A disadvantage arises in that the amount of photoresist is precipitated from the surface of the photosensitive layer, and when the increase is five times or more, sensitivity decreases. Alkali-soluble binders are particularly required for use in lithography. Alkali-soluble binders are acidic groups that are soluble in water or alcoholic alkaline solvents (including mixed systems), such as acid anhydride groups, carboxyl groups, phenolic water groups, sulfonic acid groups, sulfonamide groups, or sulfones. It is preferable that the binder, which is a polymer material containing imide bases, has a high acid value, usually 100 or more. Binder resins with high acid values easily dissolve or swell in alkaline binders. Examples of binder resins include styrene:maleic anhydride copolymer,
These are copolymers of vinyl acetate maleic anhydride, vinyl acetate crotonic acid, (meth)acrylic acid: (meth)acrylic acid ester, phenolic resin (meth)acrylic #tR: styrene = (meth)acrylic acid ester, etc.

Further, the proportion of these resins added to the photoconductor may be approximately the same as in the case of a photoconductor for copying.

Next, in the polymer film-forming binder used, the photosensitive layer is hard and weak in mechanical properties such as tension, bending, and compression. Plasticity for improvement? It is also necessary when adding a substance to give.

Substances of C1''L et al. include phthalate esters (e.g. DOP, DBP, DIDP, etc.), phosphate esters (e.g. TOP%TOP, etc.) sebacate ester, adipate ester, epoxidized soybean oil, nitrile rubber, chlorinated Examples include hydrocarbons, etc.The proportion of these substances imparting formability to the polymerizable film-forming binder is preferably between 0.1% and 20% by weight. If it is less than 0.1%, the improvement is insufficient, and if it is more than 20%, the potential characteristics will deteriorate.

Next, the sensitizing dyes that can be used without photosensitivity include triphenylmethane dyes such as methyl violet, crystal violet, ethyl violet, night blue, and Victoria blue, erythrosine, and rhodamine B10-damine 3B1. Xanthene dyes such as Acridine Red B, acridine dyes such as Acridine Orange 2G, Acridine Orange B1, Flaveosin, etc., thiazine dyes such as Methylene Blue, Methylene Green, Methyl Violet, Cabri Blue, Melt Lab- There are oxazine dyes such as exemplified by , other cyanine dyes, styryl dyes, biryllium salts, and thiapyrylium salts.

Photoconductive pigments that generate charge carriers with extremely high efficiency upon light absorption in the photosensitive layer include phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, perylene pigments such as perylene imide and perylene acid anhydride, and others. These include quinacridone pigments, azo pigments, and anthraquinone pigments.

In particular, pigments that generate charge carriers include trisazo pigments,
Those using bisazo pigments and 7-thalocyanine pigments provide high sensitivity and excellent f'L9 electrophotographic photoreceptors.

Further, the dye added to the photosensitive layer described above may be used as a charge carrier generating substance.

Although these dyes may be used alone, they often generate charge carriers with higher efficiency when they coexist with pigments. Furthermore, as inorganic original 4'Qt substances, there are selenium, selenium tellurium alloy, cadmium sulfide, zinc sulfide, etc. 0 In addition to the sensitizers (spectral sensitizers) listed above, do they further increase sensitivity? It is also possible to add all the desired sensitizers (chemical sensitizers). Examples of chemical sensitizers include p-chlorophenol, mJ
Chlorophenol p-nitrophenol, 4-chloro-
m -/resol, p-chlorobenzoylacetanilide, N%N'-diethylbarbylic acid, N1N'-diethylthiobarbyl M, 3-(β-oxyethyl)
Examples include -2-phenylimino-thiazolidone, malonic acid dianilide, 3,5°3/, 5/-tetrachloromalonic acid dianilide, α-naphthol, and p-nitrobenzoic acid.

It is also possible to add some kind of electron-withdrawing compound as a sensitizer which combines with the tetrahydroimidazole compound of the present invention to form a charge transfer complex and further increases the sensitizing effect.

Examples of this electron-withdrawing substance include 1,4-bis(p
-cyano/-flucoxycarbonylvinyl)benzene,
1-Nitroanthraquinone, 2.3-cyclonaphthoquinone, 3.3'-dinitrobenzophenone, 4-nitrobenzalmalonenitrile phthalic anhydride, 3-(α-cyano-p-nitrobenzal)phthalide, 2,4.7 −)
Examples include linitrofluorenone, l-methyl-4-nitrofluorenone, 47-sinitro-3,6-dimethylfluorenone, and the like.

Other additives such as an antioxidant and an anti-curl agent may be added to the photoreceptor as required.

The tetrahydroimidazole compound of the present invention is dissolved or dispersed in an appropriate solvent together with the various additives mentioned above depending on the shape of the photoreceptor, and the coating is applied onto the conductive support described above, Dry to produce a photoreceptor.

Coating solvents include aromatic hydrocarbons such as benzene, toluene, xylene, and monochlorobenzene, dioxane,
Bath agents such as methyl cellosolve acetate and dichloroethane can be used alone or in combination with two or more types of solvents.If necessary, solvents such as alcohols, acetonitrile, N,N-dimethylformamide, and methyl ketone can be added. 0 Next, the present invention will be explained in more detail with reference to all examples, but the present invention is not limited thereto.

Production Example (Exemplary Compound M1) N,N-diphenylamino-benzaldehyde (melting point 1
36.5-138°C) 5.4N and NIN'-diphenylethylenediamine4. ! Mk ethanol 100dK bath, then glacial acetic acid t-0,1! The mixture was heated under reflux for about 3 hours in a water bath, and then a white powder (7.2 tons) was precipitated.

Melting point: 190.0 to 192.5°C. The molecular weight is m/no 467 according to mass spectrometry (N8). Aluminum film thickness 10n)? A bisazo pigment represented by the following structural formula on a support? IXt% to n-butylamine
Dissolve the bath and apply the tomato bath solution once until the film thickness is 0.
．． Forming a film of a two-tone charge-generating substance, the tetrahydroimidazole compound shown in Exemplary Compound &3 and polyarylate resin (22 Teca mU-polymer 1t-x:t,z are mixed in a heavy residue ratio of t-x:t,z, A 10% solution T was prepared using dichloroethane as a total solvent, and this solution M was applied onto the film of the carrier generating substance using a squeezing doctor to form a carrier transfer layer having a dry film thickness of 18 μm.

The electrophotographic properties of the nine laminated electrophotographic bodies thus prepared were evaluated using a total electrostatic paper tester (Kawaguchi Denkisha 5P-428).

Measurement conditions: Applied voltage -6 KV, static capacity 3. As a result, the original half-reduced exposure sensitivity to white light during charging was 3.0 lux seconds, which was a very impressive value. After repeating the characteristic evaluation nine times and repeating it more than ten times, the original value was reduced by half.
There was no tendency for a decline in the 66-hour sensitivity of good electrophotography, including the original sensitivity.

Examples 2 to 6 Laminated photoreceptors were prepared in the same manner as in Example 1, except that the tetrahydroimidazole compound @ shown in Table 1 was used in place of the tetrahydroimidazole compound used in Example 1. Under the same measurement conditions as the original half-reduced exposure E-(
lux seconds) and initial potential Vo (volts).
The values are shown in Table 1.

Furthermore, static electricity is applied - Static neutralization (Static neutralization source: white source, 1 at 400 Lux)
After performing the same operation for 1000 cycles as the 11th cycle (second irradiation), the initial potential Vo (volt) and original half-reduction exposure amount sensitivity B- (lux seconds) 1c are shown in Table 1. Tetrahydroimidazolization of the present invention @@
It can be seen that the 7tNA element has excellent sensitivity and repeatability.

Example 7 Same as Example 1 except that a triazo pigment having the following structural formula was used instead of the 9-bisazo pigment used in Example 1.A laminated photoreceptor was prepared in the same manner. Created.

The 633 nm (He-N
The energy required to halve the potential was 6.8 erg/d (63
3nra), 5.4erg/d (670nm
) and was an extremely sensitive photoreceptor.

Note that the initial potential was 880 (volts).

Claims (1)

[Claims] (1) An electrophotographic photoreceptor characterized by containing a tetrahydroimidazole compound represented by the following general formula (I) in a photosensitive layer formed on a conductive support. ▲There are mathematical formulas, chemical formulas, tables, etc.▼……(I) (In the formula, R and R' are aralkyl groups that may contain substituents,
An aryl group or an alkyl group that may contain a substituent,
a, a', and a'' are hydrogen, lower alkyl group, and lower alkoxy group.)