JPS60188956A - Electrophotographic sensitive body superior in printing resistance - Google Patents

Abstract

PURPOSE:To enhance printing resistance, etc., by incorporating a combination of an ozone quencher and a singlet oxygen quencher in the photosensitive layer contg. a photoconductor and a dye sensitizier in an electrophotographic sensitive body. CONSTITUTION:The titled-stated electrophotographic sensitive body is obtained by mixing (A) a photoconductor, such as zinc oxide or TiO2, (B) a dye sensitizer, such as rose Bengal or eosin, (C) a binder medium, such as acrylic or epoxy resin, (D) an ozone quencher in an amt. of 0.1-100mol per mol of (B), such as 2,6-di-t-butyl-4-methylphenol, and (E) a singlet oxygen quencher in an amt. of 0.1-100mol of (B), a such as alpha-tocophenol or beta-carotene; dispersing the components of (A), (B), (D), and (E) into the component (C); and coating a support with this dispersion to form a photosensitive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electrophotographic photoreceptor with excellent printing durability, and more particularly, to a photoreceptor using a dye-sensitized photoconductor, which is capable of increasing the number of repeated copies. The present invention relates to an electrophotographic photoreceptor in which the tendency of decrease in charge amount and sensitivity caused by increase in charge is suppressed, and printing durability is thereby significantly improved.

BACKGROUND TECHNOLOGY As a relatively inexpensive photoreceptor for use in the photoreceptor method, a layer of a composition comprising dye-sensitized photoconductive zinc oxide dispersed in an electrically insulating binder resin has been developed. , those provided on conductive substrates are widely used. The number of copies that can be made (printing durability) per sheet of this zinc oxide master is generally 50.
About 0 sheets are from deer, and from the standpoint of reducing copying costs, much effort has been made to improve their printing durability.0 Factors that inhibit the printing durability of zinc oxide masks: There is a tendency for charge amount and sensitivity to decrease. In other words, even if a relatively high charge amount and sensitivity can be obtained in the initial stage of use of the mask, as the number of repeated copies increases, the charge amount and sensitivity will decrease significantly, and the resulting copied image will have a lower density. As the contrast decreases significantly, the contrast tends to decrease and fog tends to increase.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor of this type having a photosensitive layer comprising a photoconductor and a dye sensitizer dispersed in a binding medium, to increase the number of repeated copies. It is an object of the present invention to provide an electrophotographic photoreceptor in which the tendency of the resulting charge amount and sensitivity to decrease is improved.

Another object of the present invention is to provide a means for suppressing deterioration of the sensitizing dye during repeated copying in the above-mentioned type of photoreceptor.

Structure of the Invention According to the present invention, in an electrophotographic photoreceptor comprising a binding medium dispersion layer of a photoconductor and a dye sensitizer as a photosensitive layer,
An electrophotographic photoreceptor having excellent printing durability is provided, which is characterized in that the photosensitive layer contains a combination of an ozone quencher and a doublet oxygen quencher. In general, the attenuation of the above-mentioned properties of this type of photoreceptor is caused not only by the attack of ozone when the photosensitive layer is repeatedly subjected to corona discharge, but also by the attack of singlet oxygen generated by exposure. This seems to be a minor cause of deterioration of the resin and dye sensitizer in the photosensitive layer. 1- However, most of the antioxidants that are considered to be effective in preventing oxidation caused by ozone and oxygen have satisfactory effects in preventing both charge amount decay and sensitivity decay. However, the present inventors have found that when a combination of an ozone quencher and a doublet oxygen quencher is blended into this type of photosensitive layer, it is significantly effective in preventing the tendency of the charge amount to decrease and the sensitivity to decrease. It was discovered that ozone quenchers are effective against so-called ozone crack inhibitors (1).
known as antizonant),
For example, ρ-phenylenediamine derivatives, naphthylamine derivatives, quinone derivatives, aldehyde amine condensates, hydroquinones, phenol derivatives, etc. can be used, and in the present invention, phenol derivatives, particularly sterically hindered phenols, are used. Derivatives are preferred. As the sterically hindered phenol, any phenol having a sterically hindered group such as 1, t-butyl group at a position adjacent to the phenolic hydroxyl group can be used.

Suitable examples of such phenols are as follows.

2.6-ditgrt-butyl-4-methylphenol, 2.2'-methylene-bis(4-methyl-6-1ert
-butylphenol), 4.4'-methylene-bis(216-ttrt-butylphenol), 2.5-di-ttrt-butylhydroquinone, 2.5
-di-tert-amyl-hydroquinone, 2,2'-methylene-bis(4-ethyl-6-1trt-butylphenol), 4,4'-thio-bis(6-trt-butyl-m-cresol), 4.4'-Butylidene-bis(6-ttrt-butyl-
m-cresol).

7 unilene diamine derivatives such as N-N′, -acyloxy-β-hydroxy-P-phenylene diamine, and 2
, 2.4-) dimethyl-1,2-dihydro a-6-alkoxy-quinoline, etc. On the other hand, doublet oxygen quenchers are compounds that suppress photobleaching and photoembrittlement of dyes and dye-colored substrates. , refers to a substance used to improve photostability; suitable examples include carotenes such as β-carotene, lutein, carotene indo; triethylamine, diethylamine, triethylenediamine, hexamethylenetetraquine, diethylaniline. Tocopherols such as α-tocopherol: #E(II) complex of 1-nitroso-2-naphthol, Ni(II) complex of dialkyldithiocarbamic acid, A'1(II) of 8-hydroxyquinoline; ) complexes, and sulfides such as diethyl sulfide and thioanisole. Among these, tocopherols are particularly suitable for the purpose of the present invention.

In the present invention, the reason why the combination of the ozone quencher and the doublet oxygen quencher eliminates the tendency for the chargeability and sensitivity of the photosensitive layer to decrease has not yet been elucidated. In contrast to the above-mentioned problem, the attenuation of the amount of charge seems to be due to deterioration of the binding medium. In the present invention, the blended singlet oxygen quencher is capable of producing singlet oxygen generated by light irradiation of photoconductive zinc oxide.
It is believed that by quenching the -heavyt oxygen at an appropriate rate that prevents resin deterioration, the tendency for the charge amount to decay is prevented. Such an effect was discovered for the first time by the present invention.

In the present invention, there is an optimum ratio of the ozone quencher and the -1 term oxygen quencher. Immediately,
The ozone quencher is 0.1 per dye sensitizer in the photosensitive layer.
It is preferably used in an amount of 1 to 100 moles, especially 1.0 to 60 moles, while singlet oxygen/char is used in an amount of 0.1 to 100 moles, especially 1.0 to 30 moles, per dye sensitizer.
It is best to use double the mole amount. That is, if the amount of ozone quencher is less than the above range, a satisfactory effect of preventing sensitivity loss will not be obtained, whereas if it is more than the above range, the amount of charge will be lower than that of the one without the addition. If the amount of decrease is less than the above range, it will not be possible to quench the singlet oxygen generated during exposure, and the desired effect will not be obtained in preventing the charge amount and sensitivity decay. There is a tendency for the sensitivity or the amount of charge to decrease significantly.

The present invention is particularly effective in improving the printing durability of photosensitive layers using photoconductive zinc oxide among various photoconductors. The photoconductive zinc oxide used is microcrystalline, especially one with a particle size of 0.6 to 1 micron. Of course, other photoconductors that require dye sensitization can be used as photoconductors, such as oxides such as titanium dioxide, lead oxide, sulfides such as CdS, zinc sulfide, etc. .

Examples of dye sensitizers include one or a combination of two or more of rose bengal, eosin, fluoreracene, alphathrine, acid green, acridine orange, and bromophenol blue. It is used in an amount of 0.005 to 0.3% by weight, especially 0.01 to 0.2% by weight, per photoconductive pigment such as zinc.

As the binding medium, any resin used in the field, such as epoxy resin, silicone resin, urethane resin, acrylic resin, saturated polyester resin, polycarbonate resin, alkyd resin, vinyl resin, etc., can be used. Can be mentioned.

The ratio of photoconductive pigment to resin can range from 20:1 to 2:1.

The invention is illustrated by the following example.

Example 1 Preparation of photosensitive plate - Acrylic resin (LR-108, Mitsubishi Ray 5T Yon 5solid 4Q%) Using the above recipe as the basic recipe, various additives (quenchers) were added to this recipe according to Table 1. In addition, five types of samples were obtained.

Each of the above samples was dispersed using an ultrasonic dispersion machine, coated on the aluminum surface of a polyester film laminated with aluminum foil using a wire bar at a coating weight of 25 f/rd, and dried.
A photosensitive plate was obtained.

After applying a voltage of -6, OK νOat to the obtained photosensitive plate, it was irradiated with a white tungsten lamp (40lux).

After measuring the initial charge amount and sensitivity, each photosensitive plate was mounted on a cylindrical drum, and the applied voltage was set to -7.2K.
The attenuation tendency of the 0 charge amount was determined by repeating the charging-exposure process and examining the attenuation tendency of the 0 charge amount as the surface potential retention rate using the following equation.

V.

Surface potential retention rate (%) = - r,: Amount of band 11 at the 1st cycle Vn Amount of charge at the 1st cycle Also, sensitivity is expressed in terms of half-life time, and the lower the number, the better the sensitivity. -ru.

Measurements were performed every 500 cycles from 5000 to 40 DO cycles.

Figures 1 and 2 show changes in surface potential and sensitivity over time.
Shown in the figure.

C) As is clear from the graph, the Sample of the present invention
3.4.5 all obtained good results in terms of charge amount and sensitivity. In addition, in comparison with Sample 2 containing only ozone quencher, it was found that S-μe2 was effective only on sensitivity, and the charge retention rate was lower than that of blank Sam.
While it is almost the same as ple 1, the Sa of the present invention
mple showed balanced characteristics in both cases.

Example 2 Preparation of photosensitive plate A photosensitive plate was prepared using the same basic recipe as in Example 1 except for the addition of an additive (quencher).

The properties of the five types of photosensitive plates obtained were measured in the same manner as in Example 1.

The measurement results are shown in FIGS. 3 and 4.

Similar to Example 1, samples 8, 9, and 10 of the present invention gave very good results in both charge amount and sensitivity.

Example 6 The same procedure was used as the quencher in Example 1 except that nickel dithiocarbamate was used instead of α-tocopherol.Sαmpk 11 to 15 were prepared in the same manner as in Example 1, and five types of photosensitive plates were prepared ( ,Ta.

The characteristics of the obtained photosensitive plate were measured in the same manner as in Example 1.

The results are shown in FIGS. 5 and 6.

The change in sensitivity over time shown in Figure 6 shows that a constant high sensitivity can be maintained regardless of changes in the prescription, but as is clear from the change in the amount of charge over time in Figure @5, the amount of charge is also high in both overall and 17. 0 showing retention rate

[Brief explanation of the drawing]

1 and 2 show changes over time in band 'Ff, t and sensitivity in Example 1. FIGS. 6 and 4 show changes over time in charge amount and sensitivity in Example 2. 5 and 6 show changes in charge amount and sensitivity over time in Example 6. Patent Applicant Sanda Kogyo Co., Ltd. Agent Patent Attorney Ikuo Tsuchi Cycle Figure 6

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor comprising a binding medium dispersion layer of a photoconductor and a dye sensitizer as a photosensitive layer, a combination of an ozone quencher and a doublet oxygen quencher is blended into the photosensitive layer. An electrophotographic photoreceptor with excellent printing durability.