JPS59157650A - Electrophotographic sensitive agent composition - Google Patents

Abstract

PURPOSE:To obtain a satisfactory sensitization effect by incorporating nitrophthalic acid in a combination of polyvinylcarbazole (PVK)-perylene type pigment. CONSTITUTION:A perylene type electrostatic charge generating pigment is dispersed into a charge transfer medium composed essentially of a PVK type resin, and this medium incorporates nitrophthalic acid represented by the formula shown here (n being 1 or 2) as a sensitizer, in an amt. of 0.1-10, preferably, 1-4pts.wt. per 100pts.wt. PVK type resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photosensitive agent composition, and more particularly to a polyvinylcarbazole type! The present invention relates to an improvement that significantly improves the sensitivity of an electrophotographic photosensitive composition comprising a charge transport medium and a perylene charge-generating pigment dispersed in the medium.

Conventionally, a single-island type photosensitizer composition consisting of a charge-generating pigment dispersed in a charge transport medium has been prepared by dispersing a phthalocyanine pigment or A dispersion of a disazo pigment is known, but it is recognized that a dispersion of a perylene pigment in polyvinylcarbazole exhibits a sensitivity that is hardly suitable for practical use.

Conventionally, trinitroanthracene, 2, 4. Various electron acceptor substances are known, such as polycyclic or heterocyclic nitro compounds such as '7-) linitrofluorenone, acid anhydrides such as phthalic anhydride and Torino anhydride IJ') acids, and talolanil and promanil. . However, most of these known sensitizers are not yet fully satisfactory in terms of sensitivity, charging characteristics, etc. for the combination of PvK-perylene pigments.

However, the present inventors have previously found that a very satisfactory sensitizing effect can be obtained by adding halonaphthoquinones to the above-mentioned PVK-perylene pigment combination. It has been found that even better sensitivity can be obtained by adding one of these pigments to the combination of pigments.

That is, an object of the present invention is to provide a PVK-perylene pigment-dispersed photosensitizer composition that exhibits extremely superior sensitivity compared to known photosensitizers.

According to the present invention, in an electrophotographic photosensitive composition comprising a perylene pigment as a charge-generating pigment dispersed in a charge transporting medium mainly composed of polyvinylcarbazole Am resin, the following formula (%) is used: n is I to The number is 2.

Provided is an electrophotographic photosensitive composition containing nitrophthalic acid represented by the following as a sensitizer.

The nitrophthalic acid used in the present invention is a compound represented by the following general formula (%), where n is a number of 1 or 2. The most suitable nitrophthalic acids for the present invention are 4-nitrophthalic acid, 3-nitrophthalic acid, and 3,5-dinitrophthalic acid.

Of course, the above-mentioned nitrophthalic acids can be used alone or in combination of two or more. In addition, the nitrophthalic acid can also be used in combination with sensitizers consisting of other electron acceptors known per se.

The present invention is based on the finding that nitrophthalic acid specifically exhibits a sensitizing effect on dispersed PvK-Pel)L/N pigments. As is clear from the structure of formula (1), nitrophthalic acid has a chemical structural feature in which a nitro group (-NO2) with strong electron absorption is bonded to the benzene nucleus of phthalic acid. It shows electron acceptability in . Known sensitizers most similar to nitrophthalic acid, such as phthalic acid, do not exhibit an appreciable sensitizing effect on PVK-perylene photosensitizer compositions; A remarkable increase in sensitivity was observed when nitrophthalic acid was used. This indicates that the bonding of the nitro group to the benzene ring has a significant influence on the sensitizing effect of this system. Moreover, when this nitrophthalic acid is contained in a photosensitive layer made of a resin other than PVK, that is, a non-photoconductive resin-perylene pigment dispersion system, it exhibits almost no sensitizing effect. The sensitizing effect according to the invention is believed to be based on the interaction between nitro heptatalic acid and PVK.

In the present invention, it is also important to use nitrophthalic acid in an amount of 0.1 to 10 parts by weight, more preferably 1 to 4 parts by weight, per 100 parts by weight of PVK. As nitrophthalic acid was gradually added to the PVK-perylene pigment,
Sensitivity also tends to increase gradually, but once it exceeds a certain value, it tends to decrease and become practically unusable. That is, when the nitrophthalic acid is outside the above range, both the sensitivity and the amount of charge are low, and it is not suitable for the purpose of the present invention.

Polyvinylcarbazole, which serves as a charge transport medium, is a polymer consisting of the following repeating units, and has film-forming properties in itself and is an electron-donating resin. Nuclear substitutions, such as halogen or nitro substitutions, can be used as well.

As a perylene pigment, in the formula, each of R1 and R2 represents a hydrogen atom, a substituted or unsubstituted alkyl group, or an aryl group.

Pigments known per se are used.

Suitable examples of the substituent are a hydroxy group, an alkoxy group, an amide group, a nitro group, or a halogen atom.

Examples of suitable perylene pigments include, but are not limited to, the following:

N,N'-dimethylperylene-3,4,9,10-
Tetracarboxylic acid diimide, N,N'-di(3,5-dimethylphenyl)perylene-3.4,9.10-tetracarboxylic acid diimide N,N'-di,(4-ethoxyphenyl)perylene -3
,4,9,10-tetracarboxylic acid diimide, N,N'-di(4-tolyl)perylene-3,4°9.10-tetracarboxylic acid diimide.

It is also important to use the perylene pigment in an amount of 5 to 50 double image parts, particularly 10 to 30 parts by weight, per 100 parts by weight of polyvinylcarbazole; if it is less than the above range, satisfactory @sensitivity may not be obtained. Moreover, when the amount exceeds the above range, the initial saturation charging potential tends to decrease and the sensitivity also tends to decrease.

In this photoreceptor, in order to increase the mechanical strength of the photosensitive layer and further improve its adhesion to the conductive substrate, binders that do not themselves have photoconductivity, such as polyester jugeki, epoxy resin, and polycarbonate, are used. Resin, borikrekun resin, xylene resin, acrylic resin, styrene-pucdiene copolymer, etc. can be used, and these binders include polyvinyl carbazole 10 as mentioned above.
0 parts by weight to 50 parts by weight, special KIO to 3oM
It can be used in quantities of Ukm.

However, in order to improve the surface smoothness of the photosensitive layer surface, a leveling agent such as polydimethylsiloxane may be used in an amount of 0.005 to 5 parts by weight per 100 parts of polyvinylcarbazole.

The photosensitive composition of the present invention is applied as a layer of a certain thickness onto a conductive substrate and used in the form of an electrophotographic photoreceptor.

Conductive substrates include aluminum, copper, tin, 7” I
Metal foils and plates such as J-ki are used in the form of sheets or drums, and these metals can still be applied to film substrates such as biaxially stretched polyester films, glass, etc. by means such as vacuum deposition, sputtering, and electroless plating. Those applied with
NESA' glass or the like is used.

When preparing a polyvinyl carbazole for coating, first, it is dispersed in a good solvent for polyvinylcarbazole, such as tetrahydrofuran, dichloroethane, or toluene-cyclohexanone, by a means such as helilene-based stirring, and then in this dispersion. Polyvinylcarbazole and hinitrophthalic acid are dissolved in the solution. Since the nitro-heptatalic acid used in the present invention is easily soluble in a solvent, it has the great advantage that a homogeneous coating solution can be prepared. Furthermore, compared to other resins, nitro-7-talic acid has particularly excellent dispersibility in PVK, and nitro-7-talic acid, which has electron-withdrawing properties, efficiently charges electricity on the surface of perylene pigment particles. This seems to be a major factor in the inability to carry out the giving and receiving of money.

The solid content concentration of the coating liquid to be formed is 5.
It is desirable that the amount is in the range of 12% to 12% by weight.

In the present invention, the layer of the photosensitive composition is applied as a dry coating.
It should be in the range of 3 to 30 μ, especially 8 to 15 μ.
Desirable for its electrophotographic properties.

The photosensitizer composition of the present invention exhibits excellent sensitivity both when charged positively or negatively charged. However, if this photosensitive layer is positively charged and then subjected to image exposure, even greater sensitivity can be obtained.

The invention will now be illustrated by the following examples.

Example 1 A homogeneous dispersion was prepared by dispersing in a Lumir at a rotation speed of 80 rpm for 24 hours.

Next, this dispersion was added, and dispersion was continued for 24 hours at a rotational speed of 80 rpm to obtain a uniformly dispersed coating solution.

The above coating solution was applied onto an 80μ thick aluminum plate using a wire parser so that the thickness after drying was 14μ.
Drying was performed at °C for 1 hour to obtain a photoreceptor.

Examples 2 to 5 and Comparative Examples 1 to 2 Photoreceptors were prepared in the same manner as in Example 1, except that the amount of 4-nitro-heptatalic acid was changed to the formulation shown in Table 1 below.

Example 6 Using 4-ditrophthalic acid instead of 3-nitrophthalic acid
．． A photoreceptor was prepared in exactly the same manner as in Example I except that 0 part by weight was added.

The measurement was carried out using an electrostatic paper analyzer manufactured by Kawaguchi Electric under the following conditions and measurement mode.
5tat 2 Applied voltage +6.0kvolt Irradiation light White tungsten lamp 301u
xFor sensitivity, half-decreased exposure amount (Iux-sec
) was used.

The measurement results are shown in Table 2.

Claims (2)

[Claims] (1) In an electrophotographic photosensitive agent composition comprising a charge transporting medium mainly composed of a polyvinylcarbazole resin and a perylene pigment as a charge generating pigment dispersed therein, the electrophotographic photosensitive agent composition has the following formula (NOx)n, where n is 1 to 20. Electrophotographic photosensitizer composition 0 characterized by containing nitrophthalic acid represented by the number as a sensitizer (2) The composition according to claim 1, which contains nitro-heptatalic acid in an amount of 0 to 10 parts by weight of fish per 100 parts by weight of a polyvinylcarbazole resin.