JPH0446350A - Photosensitive body - Google Patents

Abstract

PURPOSE:To enhance sensitivity and stability against repeated uses without lowering potential stability and to obtain a high image stability by incorporating an oxazole or oxadiazole type laser dye in the photosensitive body comprising a conductive substrate and a photosensitive layer containing an electric charge transfer material. CONSTITUTION:The photosensitive layer formed on the conductive substrate contains the charge transfer material and in addition the oxazole or oxadiazole type laser dye, such as a compound represented by formula I in which Ar1 is phenyl, naphthyl, biphenyl, alkylphenyl, or halogenated phenyl; Ar2 is phenyl, naphthyl, or biphenyl; and (n) is 1 or 2, thus permitting the obtained photosensitive body to be small in change of initial characteristics even at the time of repeated uses and superior in performance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photoreceptor containing an oxazole or oxadiazole laser dye as an additive.

Conventional Technologies and Issues In general, in electrophotography, the surface of the photosensitive layer of a photoreceptor is charged and exposed to form an electrostatic latent image, which is developed with a developer to make it visible, and the visible image is directly printed as is. A direct method that obtains a copy image by fixing it on a photoreceptor, a powder image transfer method or a photosensitive method that transfers the visible image on the photoreceptor onto a transfer material such as paper and fixes the transferred image to obtain a copy image. The electrostatic latent image on the body is transferred onto transfer paper, and the electrostatic latent image on the transfer paper is developed.
A fixing latent image transfer method is known.

Inorganic photoconductive materials such as selenium, gadmium sulfide, and zinc oxide have been known as materials constituting the photosensitive layer of a photoreceptor used in this type of electrophotography.

Although these photoconductive materials have many advantages, such as low charge dissipation in the dark and rapid charge dissipation when exposed to light,
It has various drawbacks.

For example, the manufacturing conditions for selenium-based photoreceptors are difficult;
It is expensive to manufacture, and must be handled with care because it is susceptible to heat and mechanical shock. Cadmium sulfide photoreceptors and zinc oxide photoreceptors do not provide stable sensitivity in humid environments, and the dyes added as sensitizers cause charging deterioration due to corona charging and photobleaching due to exposure, so they cannot be used for long periods of time. It has the disadvantage that it cannot provide stable characteristics over a long period of time.

On the other hand, various organic photoconductive polymers such as polyvinylcarbazole have been proposed, but these polymers are superior to the above-mentioned inorganic photoconductive materials in terms of film formability and light weight. However, they are still inferior to inorganic photoconductive materials in terms of sufficient sensitivity, durability, and stability against environmental changes.

In addition, low molecular weight organic photoconductive compounds are preferable in that the physical properties or electrophotographic properties of the film can be controlled by selecting the type and composition ratio of the binder used in combination; Since it is used in combination with materials, high compatibility with the binder is required.

Photoreceptors in which these high-molecular-weight and low-molecular-weight organic photoconductive compounds are dispersed in a binder resin have drawbacks such as high residual potential and low sensitivity due to a large number of carrier traps. Therefore, it has been proposed to incorporate a charge transporting material into the leading conductive compound to solve the above-mentioned drawbacks.

Furthermore, a functionally separated photoreceptor has been proposed in which the charge generation function and the charge transport function of the photoconductive function are assigned to separate substances. In such functionally separated type photoreceptors, many organic compounds have been mentioned as charge transport materials used in the charge transport layer, but in practice they have various problems.

For example, 2 5-bis(P-diethylaminophenyl) 1 described in U.S. Pat. No. 3,189,447
．． ．． 3.4-Oxadiazole has low compatibility with binders and tends to form crystals.01゜U.S. Patent No. 3.82
Although the diarylalkane derivatives described in Japanese Patent No. 0.989 have good compatibility with binders, sensitivity changes occur when used repeatedly. Also, Unexamined Patent Publication No. 54-
The hydrazone compound described in Japanese Patent No. 59143 has relatively good residual potential characteristics, but has the disadvantage of poor charging ability and repeatability.

In order to satisfy the practicality as a photoreceptor, it is necessary to have excellent repeatability, optical fatigue characteristics, durability, etc. in addition to sensitivity and charging ability.

However, when organic photoreceptors are used repeatedly, their initial surface potential or light attenuation characteristics generally become unstable.
There is also the problem of severe optical fatigue and poor durability.

Techniques for improving the photosensitivity and durability of photoreceptors are known, for example, in JP-A-60-191264 and JP-A-59-123845.

Japanese Patent Application Publication No. 60-191264 discloses a technique capable of achieving excellent photosensitivity and repeatability of initial surface potential by incorporating a hydrazone compound in a photosensitive layer. This technique discloses that it is effective to add an acridine dye, a thiazine dye, or an oxazine dye to further increase photosensitivity. However, the photoreceptor still has the drawback that electrophotographic properties such as surface potential and residual potential are not stable when used repeatedly.

JP-A-59-123845 discloses an electrophotographic photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated,
Discloses a technique for improving photosensitivity characteristics by adding an electron-donating substance such as phenazine or triazole to the charge generation layer to increase injection efficiency of carriers generated in the charge generation layer into the charge transport layer. However, the present invention is not intended to solve or improve the above-mentioned repeatability characteristics, durability, etc. of the photoreceptor disclosed herein.

Further, JP-A No. 62-249167 discloses that the repeat characteristics are stabilized by adding a thioxanthone compound to the photosensitive layer, and JP-A No. 62-262053 discloses that the thiuram monosulfide compound is added to the photosensitive layer. JP-A-6230256 discloses that the repeatability is stabilized by adding a compound, and JP-A-6230256 discloses that the repeatability is stabilized by adding a triphenylmethane dye.

However, in any of the above-mentioned photoreceptors, further improvement in photoreceptor characteristics such as repeatability and durability is desired, and the types of additives are different from those of the additives disclosed in the present application.

Problems to be Solved by the Invention The present invention has been made in view of the above-mentioned circumstances. The purpose is to provide a photoreceptor that can be formed.

This object is achieved by adding an oxazole or oxadiazole laser dye to the photosensitive layer.

As a means to solve the problem, the present invention provides a photoreceptor having a photosensitive layer containing a charge transport substance on a conductive support, in which the photosensitive layer contains an oxazole or oxadiazole laser dye. The present invention relates to a characteristic photoreceptor.

In this way, by adding an oxazole-based or oxadiazole-based laser dye to a photosensitive layer containing a charge transporting substance, it is possible to obtain a photoreceptor with good performance and with little change in initial characteristics even after repeated use. .

In the present invention, oxazole-based or oxadiazole-based laser dyes refer to various derivatives having oxazole or oxadiazole as a basic skeleton, which are used as laser dyes. In the present invention, in order to be considered a laser dye, a dye must have a relatively high fluorescence quantum yield. More specifically, the transition probability from the double excited state S1 to the triple excited state T is required to be small, and it must be soluble in a suitable solvent, but especially when excited by laser light, the emission intensity of fluorescence must be low. refers to something with a strong Here, the laser light refers to, for example, a gas laser, group laser, or flash lamp.

Examples of compounds that can be used in the present invention include the following general formula [I]: [wherein, Ar is a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group or a halogenated phenyl group]
A r represents a phenyl group, a naphthyl group or a biphenyl group; n represents a number of 1 or 2;

An oxadiazole compound represented by the following general formula [11]: A metal material used as a laser dye can also be used.

Specifically, compounds represented by the following structural formula can be exemplified.

[11 [2] [3] [41 [Wherein, Ar is a phenyl group, a naphthyl group, a biphenyl group, an alkylphenyl group, or a halogenated phenyl group; Ar is a phenyl group, a naphthyl group, or a biphenyl group. R represents a hydrogen atom, a methyl group or a halogen atom; n represents a number of 1 or 2;

Examples include oxazole-based compounds represented by, but are not particularly limited to these compounds; in addition, various oxazole-based or oxadiazole-based compounds such as those that are generally commercially available [7] 8] [91 [IO] [11] [121 [13] [14] [15] [16] The photoreceptor of the present invention has a photosensitive layer containing one or more oxazole-based or oxadiazole-based laser dyes. has.

Various types of photoreceptors are known, and the oxazole or oxadiazole laser dye may be contained in the photosensitive layer of any of the photoreceptors.

For example, a single-layer photoreceptor has a charge-generating material on a support and a photosensitive layer made by dispersing the charge-generating substance in a resin binder, or a single-layer photoreceptor has a charge-generating layer mainly composed of a charge-generating material on a support. There are also so-called laminated photoreceptors in which a charge transport layer is provided thereon.

In order to produce a single-layer photoconductor, fine particles of a charge generating material are dispersed together with an oxazole or oxadiazole laser dye in a resin solution and a solution in which the charge transport material and resin are dissolved, and this is made into a conductive material. The charge transport material is generally used in an amount of 0.01 to 2 parts by weight per 1 part by weight of the binder resin. The amount added is 0.1 to this charge transport material.
-40% by weight, preferably 0.5-30% by weight, more preferably 1-20% by weight.

If the amount exceeds 4011%, the sensitivity will deteriorate.1. Residual potential increases. If it is less than 0.1% by weight, the effects of the present invention cannot be sufficiently obtained.

The thickness of the photosensitive layer is 3 to 30 μm, preferably 5 to 20 μm.
Good. If the amount of the charge generating material used is too small, the sensitivity will be poor, and if it is too large, the charging property will be poor and the mechanical strength of the photosensitive layer will be weakened. The range is preferably 1 to 311 parts by weight, preferably 0.2 to 2 parts by weight.

To produce a laminated photoreceptor, a charge-generating material is vacuum-deposited on a conductive support, or it is dissolved in a solvent such as an amine and applied, or the pigment is coated with a suitable solvent or a binder if necessary. It is obtained by coating and drying a coating solution prepared by dispersing a resin in a solution, and then coating and drying a solution containing an oxazole or oxadiazole laser dye, a charge transport material, and a binder thereon.

When forming the charge generation layer using a binder resin dispersed type,
For the same reason as when forming a single-layer type photosensitive layer, the charge generating material is used in an amount of 0.1 to 5 parts by weight per 1 part by weight of the binder resin.

In the direction transport layer, the proportion of the charge transport material in the layer is 0.2 to 2 parts by weight, preferably 0.3 to 1.3 parts by weight, based on 1 part by weight of the binder resin. Alternatively, the amount of the oxadiazole laser dye added is 0.1 to 40% by weight, preferably 0.5 to 30% by weight, based on the charge transport material, for the same reason as described for the single-layer photosensitive layer. , more preferably 1 to 20% by weight.

The thickness of the charge generation layer is preferably 4 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer is 3 to 30 μm, preferably 5 to 20 μm.

In the present invention, the electrically insulating binder resin used for forming the photosensitive layer may be a thermoplastic resin, a thermosetting resin, a photocurable resin, a photoconductive resin, etc., which are electrically insulating and are known per se. Adhesive can be used.

Examples of suitable binder resins include, but are not limited to, saturated polyester resins, polyamide resins, acrylic resins, ethylene-vinyl acetate resins, ionically crosslinked olefin copolymers (ionomers), and styrene-butadiene block copolymers. Thermoplastic resins such as polymers, polycarbonates, vinyl chloride-vinyl acetate copolymers, cellulose esters, polyimides, styrene resins: epoxy resins,
Thermosetting resins such as urethane resins, silicone resins, phenol resins, melamine resins, xylene resins, alkyd resins, thermosetting acrylic resins; photocurable resins; photoconductive resins such as polyvinylcarbazole, polyvinylpyrene, polyvinyl anthracene, polyvinyl pyrrole, etc. It is a synthetic resin.

These can be used alone or in combination.

These electrically insulating resins have a resistance of 1×1012 when measured alone.
It is desirable to have a volume resistivity of Ω·cm or more.

Charge-generating materials used for forming the photosensitive layer include bisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthine dyes, cyanine dyes, styryl dyes, pyrylium dyes, and azo pigments. ,
Quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments,
Organic substances such as induthrone pigments, squalium ring pigments, azulene pigments, and phthalocyanine pigments, selenium, selenium alloys such as selenium/tellurium, selenium/arsenic, cadmium sulfide, cadmium selenide, zinc oxide, amorphous silicon, etc. Examples include inorganic substances. In addition to these materials, any material can be used as long as it absorbs light and generates charge carriers with an extremely high probability.

Those applicable to vacuum deposition include, for example, 7-lysocyanines such as metal-free phthalocyanine, titanyl phthalocyanine, and aluminum chlorophthalocyanine.

Charge transport materials used for forming the photosensitive layer include hydrazone compounds, pyrazoline compounds, styryl compounds, triphenylmethane compounds, carbazole compounds, stilbene compounds, enamine compounds, oxazole compounds, triphenylamine compounds, tetraphenylbenzidine compounds, and azine compounds. For example, carbazole, N-ethylcarbazole, N-
Vinylcarbazole, N-phenylcarbazole, tetracene, chrysene, pyrene, perylene, 2-phenylnaphthalene, azapyrene, 2.3-benzochrysene, 3.
4-benzopyrene, fluorene, 1,2-benzofluorene, 4-(2-fluorenylazo)resorcinol,
2-p-anisoleaminofluorene, p-diethylaminoazobenzene, cation, N,N-dimethyl-p-
7enylazoaniline, p(7methylamino)stilbene, 9-(4diethylaminostyryl)anthracene,
2,5-bis(4-diethylaminophenyl)-1,3
, 5-oxadiazole, 1-7enyl-3-(p-diethylaminostyryl)-5-(p-diethylaminophenyl)pyrazoline, l-7enyl-3-7enyl-5
-Pyrazolone, 2-(p-diethylamide/styryl)-
6-Dinithylaminobenzoxazole, 2-(p-diethylaminostyryl)-6-ethylaminobenzothiazole, bis(4-diethylamino-2-methylphenyl)phenylmethane, 1,1-bis(4-NN-diethylamino) -2-ethylphenyl)hebutane, N,N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, NN-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, 1.1,2.2.
Tetrakis-(4-N,N-diethylamino-2-ethylphenyl)ethane, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diphenylaminobenzaldehyde-N, N-diphenylhydrazone, N-ethylcarbazole-N- Methyl-N-phenylhydrazone, p~diethylaminobenzaldehyde-
N-σ-naphthyl-N-phenylhydrazone, p-diethylaminobenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2-methyl-4-N, N-diphenylamino-β-phenylstilbene, σ-phenyl-4- N,N-diphenylaminostilbene, 1.1
-bis-(p-diethylaminophenyl)-4,4-diphenyl 1,3-butadiene and the like.

These transport substances may be used singly or in a mixture of two or more.

The photoreceptor of the present invention may further contain a binder resin, a plasticizer such as halogenated paraffin, polychlorinated biphenyl, dimethylnaphthalene, dibutyl phthalate, 0-terphenyl, chloranil, tetra-V a/ethylene, 2,4.
Electron-withdrawing sensitizers such as 7-dolinito-ofluorenone, 5,6-dicyazbenzoquinone, tetracyanoquinodimethane, tetrachlorophthalic anhydride, 3,5-dinitrobenzoic acid, methyl violet, rhodamine B1 cyanine dye, biryllium Sensitizers such as salts, thiapyrylium salts, etc. may also be used.

Further, antioxidants, ultraviolet absorbers, dispersion aids, anti-settling agents, etc. may also be used as appropriate.

As the conductive support used in the photoreceptor of the present invention, a sorted or drum-shaped foil or plate of metal or alloy such as copper, aluminum, silver, iron, zinc, or nickel is used; A metal is vacuum-deposited or electrolessly plated on a plastic film, etc., or a layer of a conductive compound such as a conductive polymer indium oxide or tin oxide is coated or vapor-deposited on a support such as paper or a plastic film. The one given is used.

Incidentally, the photoreceptor obtained as described above may be provided with an adhesive layer, a barrier layer, and a surface protection layer, if necessary.

Materials used for the intermediate layer include polymers such as polyimide, polyamide, nitrocellulose, polyvinyl butyral, and polyvinyl alcohol as they are, or in which low-resistance compounds such as tin oxide and indium oxide are dispersed, aluminum oxide, zinc oxide, A vapor deposited film of silicon oxide or the like is suitable.

Further, the thickness of the intermediate layer is preferably 1 μm or less.

Materials used for the surface protective layer include acrylic resin,
Polymers such as polyaryl resins, polycarbonate resins, and urethane resins are suitably used as they are, or those in which low-resistance compounds such as tin oxide and idium oxide are dispersed.

An organic plasma polymerized film can also be used. The organic plasma polymerized film may optionally contain oxygen, nitrogen, halogen, and atoms of the third wind and group five of the periodic table, as required.

Further, the thickness of the surface protective layer is desirably 5 μm or less.

Note that the photoreceptor of the present invention can also be used as a photoreceptor for laser printers.

Example 1 Bisazo compound represented by the following chemical formula (A): [A] 1 part by weight (hereinafter, part by weight is referred to as "part"), 1 part of polyester resin (V-200: manufactured by Toyobo Co., Ltd.) were cyclo It was dispersed using a sand glider together with 90 parts of hexanone. The obtained dispersion of the hisazo compound was coated on an aluminum drum to a dry film thickness of 0.2 g/m'' and dried to form a charge generation layer.

The following chemical formula [
Butadiene compound represented by [B]: 10 parts and polycarbonate resin (-1
300, manufactured by Ondai Kasei Co., Ltd.) 10 parts with 8 parts of tetrahydrofuran
A coating solution containing 0.5 parts of compound [21] was applied by dipping and dried to form a charge transport layer having a thickness of about 20 μm. In this way, an electrophotographic photoreceptor having a two-layer photosensitive layer was obtained.

Examples 2 to 4 Photoreceptors were produced in the same manner as in Example 1, except that the amounts of compound [2] added were 0.25 parts, 0.75 parts, and 1 part.

Comparative Example 1 A photoreceptor was produced in the same manner as in Example 1 except that compound [2] was not added.

Comparative Example 2 In Example 1, 2.5-
A photoreceptor was prepared in the same manner as in Example 1 except that 0.5 part of di-ter-butyl-p-cresol was added.

Comparative Example 3 A photoreceptor was produced in the same manner as in Example 1 except that 0.5 part of trinolylphenyl phenyl phosphite was added instead of compound [2].

Comparative Example 4 A photoreceptor was produced in the same manner as in Example 1 except that 065 parts of phenazine was added instead of compound [2].

Comparative Example 5 In Example 1, compound [21 was replaced with 2-(2
A photoreceptor was prepared in the same manner as in Example 1 except that 0.5 part of '-hydroxy-5'-methylphenyl)benzotriazole was added.

Example 5 One part of a bisazo compound represented by the following chemical formula [C]: [C] and one part of butyral resin (BH-3, manufactured by Okisui Kagaku Co., Ltd.) were dispersed together with 90 parts of 7-chlorhexanone using a sand mill. The obtained bisazo compound dispersion was coated on an aluminum drum so that the film thickness after coating was 0.2 g/m2, and then dried.

The following chemical formula [
D] distyryl compound: CH.

CH.

[D] 10 parts, 10 parts of polycarbonate resin (PC-Z: manufactured by Mitsubishi Gas Chemical Co., Ltd.) were dissolved in 80 parts of tetrahydrofuran,
A coating solution containing 0.3 parts of compound [3] was applied by dipping to form a charge transport layer with a thickness of about 20 μm.

As described above, a photoreceptor having a two-layer photoreceptor layer was obtained.

Comparative Example 6 A photoreceptor was produced in the same manner as in Example 5 except that compound [31 was not added.

Comparative Example 7 A photoreceptor was produced in the same manner as in Example 5 except that 0.3 parts of the surfactant pholyoxyethylene nonylphenyl ether was added in place of compound [3].

Example 6 4.5 parts of σ-type titanyl phthalocyanine, 4.5 parts of butyral resin (BX-1: manufactured by Okisui Kagaku Co., Ltd.) and compound [6
] 0.45 parts were dispersed in a sand mill with 500 parts of dichloroethane. The resulting dispersion was applied onto an aluminum drum to a coating thickness of 0.2 g/m'' and then dried.

The chemical formula [
B] butadiene compound IO moiety represented by and chemical formula [
A solution prepared by dissolving 40 parts of hydrazone compound represented by [E] and 50 parts of polyarylate (U-100: manufactured by Unitika) in 500 parts of tetrahydrofuran was applied and dried to form a film with a thickness of about 15 μm. A charge transport layer was formed.

In this way, a photoreceptor having a two-layer photoreceptor layer was obtained.

Example 7 - lO In Example 6, the amount of compound [6] added was 0°23 parts,
A photoreceptor was produced in the same manner as in Example 6 except that the amounts were changed to 0.68 parts, 0.9 parts, and 1.35 parts.

Comparative Example 8 A photoreceptor was produced in the same manner as in Example 6 except that compound [6]j was not added.

Comparative Example 9 A photoreceptor was produced in the same manner as in Example 6 except that 0.45 parts of trinitrofluorenone was added instead of compound [6].

Comparative Example 1O LH-1゜2 instead of compound [6] in Example 6
．． A photoreceptor was prepared in the same manner as in Example 6 except that 0.45 parts of 4-triazole was added.

Evaluation The photoreceptor thus obtained was transferred to a commercially available electrophotographic copying machine (EP).
-50 (50φ): manufactured by Minolta Camera Co., Ltd.), -6
The initial surface potential VO (V) is the exposure amount E +/2 (l
ux-sec), and the decay rate DDRI (%) of the initial potential when left in the dark for 1 second was measured.

The results are shown in Table 1.

Further, the photoreceptor was attached to a photoreceptor tester (FIG. 1) having the same configuration as a copying machine, and the electrophotographic characteristics were measured.

That is, the photoreceptors obtained in Examples and Comparative Examples were attached to a photoreceptor drum (1), and a charger (2) was used to apply a voltage of -500V.
Initial surface potential (Vo) of the photoreceptor 0.3 seconds after charging
, After charging, the surface potential (Vl) after exposure to white light from a halogen lamp (3) and the photo eraser (5
) The residual potential (V, ) after static elimination was measured using the probe (4), and the V after repeating the above process 5000 times. , ■, and V were measured, and the repeatability was investigated.

The results are shown in Table 2.

Table 1 (Hereinafter, blank space) Table ■ (Continued) Effects of the invention The photoreceptor of the present invention has the following advantages:
Sensitivity and repetition stability can be improved, and high image stability can be obtained.

[Brief explanation of drawings]

Figure wc1 is a diagram showing a schematic configuration of a photoreceptor tester. Patent applicant: Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. A photoreceptor having a photoreceptor layer containing a charge transport substance on a conductive support, characterized in that the photoreceptor layer contains an oxazole-based or oxadiazole-based laser dye.