JPS63291063A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent deterioration due to light and to retain photosensitivity characteristics and electric characteristics for a long time without deteriorating abrasion resistance by incorporating an ultraviolet absorber and an antioxidant in a protective layer. CONSTITUTION:The protective layer formed on the surface of a photosensitive body contains the ultraviolet absorber such as benzophenone type, benzotriazole type, benzoate type, and acrylonitrile type ultraviolet absorbers and the antioxidant, such as amine type, phenol type, sulfur type, phosphoric acid type, hydroquinone type, quinoline type, and nickel salt type antioxidants, thus permitting deterioration of the photosensitive layer to be prevented without abrasion resistance and the like, and the photosensitivity characteristics and electric characteristics to be stabilized for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic photoreceptor useful as an organic photoreceptor.

<Prior Art> In recent years, organic photoreceptors have been known as photoreceptors for electrophotography, which have good processability and are advantageous in terms of manufacturing cost, and also have a large degree of freedom in functional design. This organophotoreceptor is usually
A photosensitive layer is formed on a conductive substrate, and the photosensitive layer is a single-layer type containing a charge-generating material that generates charges when irradiated with light and a charge-transporting material that transports the generated charges. and a charge generation layer containing a charge generation material;
Multilayer organic photoreceptors are known in which each function is separated by a charge transport layer containing a charge transport material. Further, in order to improve the abrasion resistance of the organic photoreceptor, a protective layer is usually formed on the surface of the photosensitive layer.

On the other hand, since the photosensitive layer generally contains a charge transporting material etc. that is easily photodegraded, it is exposed to active ozone, etc. generated by corona discharge during charging, and light, especially ultraviolet rays, during the exposure process and maintenance. Irradiation with short wavelength light causes early deterioration and deterioration of the electrophotographic photoreceptor, reducing the sensitivity and surface potential of the photoreceptor, while increasing the residual potential, reducing image density and increasing fog. Problems such as

In order to solve the above-mentioned problems, a photoreceptor with an antioxidant added to the protective layer (Japanese Unexamined Patent Publication No. 59-138744) and a photoreceptor with an ultraviolet absorber added (Japanese Unexamined Patent Publication No. 58-160) were developed.
No. 957) is known.

<Problems to be Solved by the Invention> However, the conventional photoreceptor described above still does not have sufficient stability. In other words, with a photoreceptor containing an antioxidant, if the amount added is small, it will not only be impossible to prevent deterioration of the photosensitive layer, but if the amount added is too large, the charge-generating material will form at the interface with the photosensitive layer. The antioxidant in the protective layer acts as a carrier trap by interacting with photosensitive materials such as photosensitive materials and charge transport materials, resulting in lower initial sensitivity and increased residual potential in the photoreceptor due to repeated use. There is. On the other hand, according to a photoreceptor containing an ultraviolet absorber,
For example, unless a large amount of ultraviolet absorber (50% by weight or more) is added, it is not only impossible to prevent the photosensitive layer from deteriorating, but if the amount of ultraviolet absorber added is too large, the abrasion resistance decreases, making it difficult to use as a protective layer. ceases to fulfill its role. Therefore, in the above-mentioned conventional photoreceptors, it is not possible to prevent deterioration of the photoreceptor with a small amount of addition, and to simultaneously satisfy the photosensitive characteristics, electrical characteristics, and abrasion resistance of the photoreceptor. There is a problem in that it is difficult to maintain stable characteristics and electrical characteristics over a long period of time.

<Object of the Invention> The present invention has been made in view of the above-mentioned problems, and it prevents deterioration of the photosensitive layer with a small amount of addition without reducing wear resistance etc. Another object of the present invention is to provide an electrophotographic photoreceptor exhibiting stable photosensitive characteristics and electrical characteristics.

Means and Effects for Solving the Problems In order to achieve the above objects, the electrophotographic photoreceptor of the present invention is an organic photoreceptor having a protective layer on the surface, wherein the protective layer contains an ultraviolet absorber and an antioxidant. It is characterized by containing.

According to the electrophotographic photoreceptor having the above structure, since the protective layer contains an ultraviolet absorber and an antioxidant, deterioration of the photoreceptor can be prevented with a small amount of addition, and the abrasion resistance of the photoreceptor layer is reduced. The photoreceptor can be stabilized for a long period of time without causing any damage.

The present invention will be explained in detail below.

The present invention can be applied to various types of photoreceptors having a protective layer on the surface, such as a photoreceptor having a single-layer type photoreceptor layer as shown in FIG. That is, a photosensitive layer (4) containing a charge transporting material, a charge generating material, a binder resin, etc. and a protective layer (5) are sequentially formed on a conductive substrate (1), or a second layer is formed on a conductive substrate (1). As shown in the figure, a photoconductor having a multilayer photoconductor layer, that is, a conductive substrate (11), a charge transport layer (12) containing a charge transport material, a binder resin, etc., and a charge generating layer A photosensitive layer (14) consisting of a charge generation layer (13) containing a material and a protective layer (15) are formed in sequence, or the charge generation layer and charge transport layer are laminated in the reverse order. Examples include photoreceptors having a photosensitive layer.

The above-mentioned conductive substrates (1) and (11) may be in the form of a sheet or a drum, and either the substrate itself is conductive or the surface of the substrate is conductive, and a sufficient mechanical It is preferable that the material has a strong target strength.

As the conductive substrate, various conductive materials can be used, such as aluminum 7m, aluminum alloy,
Single metals such as copper, tin, platinum, gold, silver, vanadium, molybdenum, chromium, cadmium, titanium, nickel, palladium, indium, stainless steel, and brass, as well as the above metals, indium oxide, tin oxide, etc., by means such as vapor deposition. Examples include layered plastic materials and glass.

Examples of the charge generating material for the photosensitive layer (4H14) include selenium, selenium-tellurium, amorphous silicon,
Pyrylium salts, azo pigments, disazo pigments, trisazo pigments, anthanthrone pigments, phthalocyanine pigments, indigo pigments, triphenylmethane pigments, threne pigments, toluidine pigments, pyrazoline pigments, perylene pigments, Examples include quinacridone pigments.

In addition, examples of the charge transporting material include chloranil, tetracyanoethylene, 2,4,7-dolinitro 9
- Fluorenone compounds such as fluorenone, 2.4.8
-) Nitrated compounds such as linitrothioxanthone and dinitroanthracene, N,N-diethylaminobenzaldehyde N.

Hydrazone compounds such as N-diphenylhydrazone, N-methyl-3-carbazolylaldehyde N,N-diphenylhydrazone, 2,5-di(4-dimethylaminophenyl)-1,3,4-oxadiazole, etc. oxadiazole compounds, styryl compounds such as 9-(4-diethylaminostyryl)anthracene, carbazole compounds such as N-ethylcarbazole, 1-phenyl-3
Pyrazoline compounds such as -(4-dimethylaminophenyl)pyrazoline, 2-(4-diethylaminophenyl)-4-(4-dimethylaminophenyl)-5-(2-
Oxazole compounds such as chlorophenyl)oxazole, isoxazole compounds, thiazole compounds such as 2-(4-diethylaminostyryl)-6-dinithylaminobenzothiazole, thiadiazole compounds, imidazole compounds, pyrazole compounds, indole compounds compounds, nitrogen-containing cyclic compounds such as triazole compounds, fused polycyclic compounds, succinic anhydride, maleic anhydride,
Examples include dibromomaleic anhydride, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, and ethylcarbazole-formaldehyde resin.

Among the charge transport materials mentioned above, the present invention is directed to charge transport materials that are excellent in charge transport properties but tend to deteriorate due to light irradiation, etc., and whose photosensitivity properties etc. tend to deteriorate, particularly those that undergo isomerization, trimerization, etc. due to light irradiation, etc. It is particularly useful when applied to a photoreceptor having a photosensitive layer containing the above-mentioned hydrazone compound, which is likely to cause .

In addition, various binder resins can be used, such as styrene polymers, styrene-butadiene copolymers, styrene-acrylonitrile copolymers, styrene-maleic acid copolymers, acrylic polymers, and styrene-acrylic copolymers. system copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester, alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone 3. Resin, ketone resin, polyvinyl butyral resin, polyether resin, phenol resin, epoxy acrylate,
Examples include various polymers such as photocurable resins such as urethane acrylate. Note that photoconductive polymers such as the poly-N-vinylcarbazole can also be used as the binder resin.

The ratio of the charge generating material, the charge transporting material, and the binder resin in the photoreceptor having the single-layer photoreceptor layer (4) may be appropriately selected depending on the desired characteristics of the organic photoreceptor. However, for 100 parts by weight of binder resin,
2 to 20 parts by weight of charge generating material, preferably 5 to 10 parts by weight, 25 to 150 parts by weight of charge transporting material, preferably 50 parts by weight.
~100 parts by weight are used. If the amount of charge generating material and charge transporting material used is less than the above-mentioned amount, not only the sensitivity of the photoreceptor will not be sufficient, but also the residual potential will become large. Moreover, when the above range is exceeded, the surface potential of the photoreceptor decreases. Further, the single-layer type photosensitive layer (4) may have an appropriate thickness, but preferably has a thickness of 3 to 50 μm, particularly 5 to 25 μm.

Further, when forming the charge transport layer (12) in the multilayer photosensitive layer (14), the ratio of the charge transport layer material and the binder resin can be set as appropriate;
It is preferable to use 25 to 500 parts by weight, particularly 100 to 300 parts by weight, of the binder resin per 00 parts by weight. If the amount of the binder resin is less than 30 parts by weight, the mechanical strength etc. of the charge transport layer will decrease, and if it exceeds 500 parts by weight, the charge transport ability will not be sufficient.

The charge transport layer (12) may have an appropriate thickness, but preferably has a thickness of about 2 to 100 μm, particularly about 5 to 30 μm. Note that the charge transport layer (12
) The photoconductive polymers described above can also be used as the binder resin.

In addition, the charge generation layer (1) in the multilayer photosensitive layer (14)
3) may be formed using the binder resin or the like, or may be formed by vapor depositing, sputtering, etc. the charge generating material on the conductive substrate (11) without using the binder resin. When the charge generation layer (13) is formed using a binder resin or the like, the charge generation layer (13) contains 1 to 300 parts by weight, particularly 5 to 150 parts by weight of the binder resin based on 100 parts by weight of the charge generation material. It is preferable to use 10%. If the amount of the binder resin or the like is less than 1 part by weight, there will be problems such as a decrease in the adhesion of the photosensitive layer to the conductive substrate (11), and if it exceeds 300 parts by weight, the charge generation ability will be reduced. The charge generation layer (1
3) may have an appropriate thickness, but from 0.01 to
It is preferable to have a thickness of about 5μ0, especially about 0.1 to 3μ.

Note that, except when the charge generation layer (13) is formed by means such as vapor deposition, the charge transport layer (12), etc. in the single-layer type photosensitive layer (4) or multi-layer type photosensitive layer (15) are can be formed by applying a dispersion of the charge transporting material and an organic solvent onto the conductive substrates (1) and (11) and removing the solvent. Further, the above dispersion can be prepared by a conventional method such as a ball mill, a paint shaker, a sand mill,
It can be prepared using an attritor, an ultrasonic disperser, etc., and various coating means can be employed when applying the obtained dispersion.

The photosensitive layers (4) and (14) may contain additives such as conventionally known sensitizers and plasticizers such as terphenyl, noronaphthoquinones, and acenaphthylene. Also,
An undercoat layer is formed between the conductive substrate (1) (11) and the photosensitive layer (4) (14), or a charge generation layer (13)
An intermediate layer may be formed between the charge transport layer (12) and the charge transport layer (12).

The protective layers (5) and (15) maintain abrasion resistance, prevent deterioration of the photosensitive layer, and maintain stable photosensitive characteristics and electrical characteristics over a long period of time. Contains absorbents and antioxidants.

As the binder resin, various of the above-mentioned ones can be used, including acrylic polymers, styrene-acrylic copolymers, polyesters, polyamides, polyimides, polycarbonates, and polyarylates, which have excellent mechanical properties such as abrasion resistance. , thermoplastic resins such as polysulfone, polyvinyl butyral resin, and polyether resin; thermosetting resins such as thermosetting acrylic polymers, alkyd resins, unsaturated polyesters, polyurethanes, epoxy resins, diallyl phthalate resins, silicone resins, and phenolic resins. Resins, photocurable resins such as epoxy acrylate, urethane acrylate, etc., and particularly the above-mentioned thermosetting resins and photocurable resins that have excellent abrasion resistance are preferable.

Various types of UV absorbers can be used, such as benzophenone UV absorbers, benzotriazole UV absorbers, benzoate UV absorbers, acrylonitrile UV absorbers, and other UV absorbers.

Examples of the benzophenone ultraviolet absorbers include:
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Octyloxybenzophenone, 4-dodecyloxy-
2-hydroxybencyphenone, 2-hydroxy-4-
Octadecyloxybenzophenone, 2.2''-dihydroxy-4-methoxybenzophenone, 2.2-dihydroxy-4,4'-dimethoxybenzophenone, 2.
2=, 4.4-tetrahydroxybenzophenone, 2
-Hydroxy-4,4'-dimethoxy-3-,5-di-tert-butylbenzophenone, 2,4-dihydroxy-3-,5-di-tert-butylbenzophenone, 2,4-dihydroxy-3- , 5-diisopropylbenzophenone, 2,4'-dihydroxy-4-
Pentyloxy-3-,5-diisopropylbenzophenone, 2-hydroxy-4-chlorobenzophenone,
Examples include 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, and 2-hydroxy-4-(2-hydroxy-3-methacryloxy)propoxybenzophenone.

In addition, examples of benzotriazole-based ultraviolet absorbers include 2-(2-hydroxy-5-methylphenyl)
Benzotriazole, 2-(2-hydroxy-3,5
-dimethylphenyl)benzotriazole, 2-(2-
Hydroxy-3-tert-butyl-5-methylphenyl)benzotriazole, 2-(2-hydroxy-3
,5-di-tert-butylphenyl)benzotriazole, 2-(2-hydroxy-4-octyloxyphenyl)benzotriazole, 2-(2-hydroxy-5-pentylphenyl)benzotriazole, 2-
(2-hydroxy-3,5-dimethylphenyl)benzotriazole, 2-(2-hydroxy-5-hexylphenyl)benzotriazole, 2-(2-hydroxy-3-methyl-5-hexylphenyl)benzotriazole , 2- (2-hydroxy-5-methylphenyl)
-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-dimethylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3-methyl-5-
tert-butylphenyl)-5-chlorobenzotriazole, 2-(2-hydroxy-3,5-di-tert
-butylphenyl)-5-chlorobenzotriazole,
Examples include 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole.

In addition, examples of benzoate-based ultraviolet absorbers include:
Phenyl salicylate, 4-tert-butylphenyl salicylate, 4-octylphenyl salicylate, 2,
4-tert-butylphenyl-3,5-tert
Examples include rt-butyl-4-hydroxybenzoate and resorcinol monobenzoate. In addition, as an acrylonitrile-based ultraviolet absorber, 2-ethyl-2-
Examples include cyano-3゜3-diphenylacrylate, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, and other ultraviolet absorbers include [2
, 2-thiobis(4-tert-octylphenolate)cobutylamine nickel, nickel-based ultraviolet absorbers such as nickel bis(octylphenyl sulfide), and the like.

The above-mentioned ultraviolet absorbers can be added in an appropriate amount depending on the type of binder resin, the type of ultraviolet film coating agent, etc., but benzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers can achieve the above effects with a small amount of addition. Absorbers, benzoate-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers are particularly preferred. Further, the above-mentioned ultraviolet absorbers may be used alone or in combination of two or more.

In addition, antioxidants include amine antioxidants, phenolic antioxidants, sulfur antioxidants, phosphorus antioxidants, hydroquinone antioxidants, quinoline antioxidants, and nickel salt antioxidants. , other antioxidants are used.

Examples of the above amine antioxidant include phenyl-
α-naphthylamine, phenyl-β-naphthylamine,
Reaction product of diphenylamine and acetone, N, N-
-diphenyl-p-phenylenediamine, N,N--di-β-naphthyl-p-phenylenediamine, N,N--
Diheptyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, N-
Isopropyl-N'-phenyl-p-phenylenediamine, N,N-di(1-ethyl-3-methylpentyl)
-p-phenylenediamine, N.

N”-di(1-methylheptyl)-p-phenylenediamine, N,N-diallyl-p-phenylenediamine,
N-phenyl-N--(1,3-dimethylbutyl)-p
-phenylenediamine, N+N'-di(1,4-dimethylpentyl)-p-phenylenediamine, N-phenyl-N--(1-methylpropyl)-p-phenylenediamine, N-phenyl-N--(1 -methylheptyl)
Examples include -p-phenylenediamine, N,N-diphenylethylenediamine, and the like.

In addition, examples of phenolic antioxidants include 2.
4-dimethyl-6-tert-butylphenol, 2,
6-tert-butylphenol, 3゜5-tert-butylphenol
ert-butyl-4-hydroxytoluene, 4,4-monothiobis(6-tert-butyl-m-cresol),
4.4-thiobis(6-tert-butyl-0-cresol), 2.2'-thiobis(4-methyl-6-tc
rt-butylphenol), 2.2-monethylenebis(
4-methyl-6-tert-butylphenol), 2.
2-Methylenebis(4-ethyl-6-tert-butylphenol), 4.4-methylenebis(2,6-tert-butylphenol), 4.4-bis(2-tert-butylphenol)
, 6-tert-butylphenol), 4.4-
-methylenebis(6-tert-butyl-0-cresol), 1,3,5-trimethyl-2,4,6-tris(
3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 4,4-butylidene bis(6-tert)
(t-butyl-m-cresol), styrenated phenol, and the like.

Further, examples of the sulfur-based antioxidant include dilaurylthiodipropionate, distearylthiodipropionate, laurylstearylthiodipropionate, simiristylthiodipropionate, and the like.

Examples of phosphorus antioxidants include triisodecylphosphite, diphenylisodecylphosphite,
Examples include triphenylphosphite and trinonylphenylphosphite.

Examples of hydroquinone antioxidants include 2.5-
Di-tert-butylhydroquinone, 2,5-tert-butylhydroquinone
Examples include rt-amylhydroquinone.

As a quinoline antioxidant, for example, 2゜2.4-
Examples include trimethyl-1,2-dihydroquinoline, 6-nitoxy-2.2.4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline, etc. .

Examples of the nickel salt antioxidant include nickel dibutyldithiocarbamate, nickel isopropylxanthate, and the like.

Other antioxidants include 2-mercaptobenzimidazole, N-sadicilloyl-N--aldehydehydrazine, N-salicilloyl-N'-acetylhydrazine, N,N''-diphenyloxamide, N,N-di(2
-hydroxyphenyl)oxamide and the like.

The above antioxidant can be added in an appropriate amount depending on the type of antioxidant, but amine antioxidants, phenolic antioxidants, and nickel salt antioxidants are preferred. The above antioxidants may be used alone or in combination of two or more.

The above-mentioned ultraviolet absorbers and antioxidants can be used in appropriate proportions depending on their types, etc., but in the protective layer (5) (15)
5 to 4 parts of ultraviolet absorber per 100 parts by weight of binder resin.
0 parts by weight, preferably 15-35 parts by weight, more preferably 20-30 parts by weight, antioxidants 1-10 parts by weight, preferably 2.5-10 parts by weight, more preferably 5-10 parts by weight. used in If the amount of the ultraviolet absorber is less than 5 parts by weight, the effect of preventing deterioration of the photosensitive layer will not be sufficient and the residual potential of the photoreceptor after irradiation with light will become large, and if it exceeds 40 parts by weight, the abrasion resistance of the photosensitive layer will deteriorate. Shows a decreasing trend.

Furthermore, if the amount of antioxidant is less than 1 part by weight, deterioration of the photosensitive layer cannot be sufficiently prevented, and if it exceeds 15 parts by weight, the initial sensitivity of the photoreceptor will decrease and the residual potential will increase due to repeated use. There is a tendency to

In addition, the above-mentioned ultraviolet absorber and antioxidant can be added in appropriate amounts within the above-mentioned range.
In order to further increase the abrasion resistance of the photosensitive layer and to prevent deterioration of the photosensitive layer, the total amount of the ultraviolet absorber and antioxidant is
It is preferably set to 40 parts by weight or less, particularly 25 to 40 parts by weight.

The protective layers (5) and (15) can be formed by applying a coating solution containing the binder resin, an ultraviolet absorber, and an antioxidant using a conventional coating method such as dip coating, spray coating, spin coating, or roller coating. It can be formed by coating on the photosensitive layer (4) (14) by coating, blade coating, curtain coating, bar coating, or the like. Further, the protective layers (5) and (15) can be formed to have an appropriate thickness, but are formed to have a thickness of 0.1 to 10 μm, preferably 1 to 5 μm.

When preparing the above coating liquid, an appropriate organic solvent is used depending on the type of binder resin, etc. Examples of the organic solvent include aliphatic hydrocarbons such as n-hexane, octane, and cyclohexane, and benzene. , aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride, and chlorobenzene, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether; Examples of various solvents include ketones such as acetone, methyl ethyl ketone, and cyclohexanone, esters such as ethyl acetate and methyl acetate, dimethyl formamide, and dimethyl sulfoxide, which may be used singly or in combination of two or more. In addition, the above coating liquid is
In order to improve dispersibility, coating properties, etc., a surfactant, a leveling agent, etc. may be contained.

As described above, in the electrophotographic photoreceptor of the present invention, since the protective layer contains an ultraviolet absorber and an antioxidant, ozone generated by corona discharge, photosensitive characteristics of the photoreceptor due to light irradiation, etc. Deterioration of optical properties can be prevented with a small addition amount, and the photosensitive layer has excellent abrasion resistance. Therefore, the electrophotographic photoreceptor of the present invention is useful as a photoreceptor for copying machines, laser printers, and the like.

<Examples> The present invention will be described in more detail below based on Examples.

Examples 1 to 7 Photoreceptors having a single-layer photosensitive layer were manufactured using an aluminum plate as a conductive substrate. Namely, 1 part by weight of dibromoanthanthrone, 8 parts by weight of N,N-diethylanobenzaldehyde N,N-diphenylhydrazone, polycarbonate (trade name Panlite L122 manufactured by Teijin Kasei Co., Ltd.)
5) A dispersion was prepared using a ball mill using 10 parts by weight and a predetermined amount of tetrahydrofuran, and the dispersion was coated on the aluminum plate to produce a photoreceptor having a photosensitive layer with a thickness of approximately 20 tones.

Next, 2-(2-hydroxy-
While adding 5-tert-butylphenyl)benzotriazole and nickel dibutyldithiocarbamate as an antioxidant in the proportions (parts by weight) shown in the table,
A tetrahydrofuran solution for a protective layer was prepared using a predetermined amount of tetrahydrofuran.

Then, the obtained tetrahydrofuran solution for a protective layer was applied onto the photosensitive layer, dried by heating, and cured to form a protective layer having a thickness of 2 μm, thereby obtaining an electrophotographic photoreceptor of the present invention.

Comparative Examples 1 and 2 Thermosetting modified urethane resin 100 used in the above example was used in place of the tetrahydrofuran solution for the protective layer in the above example.
Based on parts by weight, 2-(2-hydroxy-5-tert
-butylphenyl)benzotriazole in 25 parts by weight (
A tetrahydrofuran solution prepared by adding 50 parts by weight of Comparative Example 1) and 50 parts by weight (Comparative Example 2) was applied onto the photosensitive layer of the photoreceptor prepared in the above example, and a film thickness of approximately An electrophotographic photoreceptor having a protective layer of 2 μm was obtained.

Comparative Examples 3 and 4 Instead of the tetrahydrofuran solution for the protective layer in the above example, 5 parts by weight of nickel dibutyldithiocarbamate (Comparative Example 3), 20 An electrophotographic photoreceptor was obtained in the same manner as in the above example using a tetrahydrofuran solution prepared by adding parts by weight (Comparative Example 4).

The characteristics of the above electrophotographic photoreceptor were investigated by the following method.

(a) Photosensitive properties and surface potential Electrostatic copying paper test device (Kawaguchi Electric Co., Ltd. SP~428 type)
Each photoreceptor was positively charged by performing corona discharge under the conditions of +B and OKV.

In addition, the initial surface potential V i m of each photoconductor was measured, and the photoconductor surface was exposed to light using a tungsten lamp adjusted so that the illumination intensity was IOlux, until the surface potential Vi was reduced to 1/2. Find the time and half the exposure E
1/2 (lux, ·see,) was calculated. In addition, the surface potential after 0.15 seconds after exposure is the residual potential V
r, p, and m.

(b) Photodegradability After irradiating each photoreceptor with a white fluorescent lamp of 3000 lux for 15 minutes, the residual potential was measured in the same manner as in (a) above, and the initial residual potential V r, p of the photoreceptor was measured. .

The difference from the above was expressed as ΔVr,p, (V).

(e) Repeatability characteristics The charging and exposure steps in (a) above are repeated 1000 times, and the residual potential of the photoreceptor after 1000 repetitions is determined as shown in (a) above.
Measured in the same manner as the initial residual potential Vr of the photoreceptor,
The difference from p, was expressed as ΔV r,p, 1000 (V).

(d) Each of the electrophotographic photoreceptors described above was installed in a wear-resistant copying machine (Model DC-111 manufactured by Sanda Kogyo Co., Ltd.), and 1,000 copies were made using dry toner.
After copying 0 sheets, the wear amount (μff1) is determined from the difference between the initial thickness of the protective layer and the thickness of the protective layer after copying 10,000 sheets.
I asked for

The results of the photosensitive characteristics, charging characteristics, repeatability characteristics, etc. of each electrophotographic photoreceptor obtained in the above Examples and Comparative Examples are shown in the following table.

As is clear from the table, in a protective layer containing only an ultraviolet absorber, when the amount of ultraviolet absorber is small, photodeterioration of the photosensitive layer occurs;
If it is too large, the wear resistance will be poor (Comparative Example) and 2). On the other hand, in a protective layer containing only an antioxidant, it was found that a small amount of antioxidant caused photodeterioration, and a large amount resulted in a decrease in initial sensitivity and poor repeatability (Comparative Examples 3 and 4).
. Further, the samples of Comparative Examples, especially those of Comparative Example 3, had a large residual potential. Therefore, according to the electrophotographic photoreceptors of Comparative Examples 1 to 4, it is not possible to simultaneously satisfy the photosensitive characteristics, electrical characteristics, abrasion resistance, etc. of the photoreceptor. On the other hand, according to the electrophotographic photoreceptor of the present invention, the photoreceptor can be stabilized with a small amount of addition. That is, it was found that not only the sensitivity did not decrease and the residual potential was small, but also it was possible to prevent photodeterioration and deterioration due to repeated use, and it was also excellent in abrasion resistance.

Example 8 Using 100 parts by weight of the thermosetting modified urethane resin of Example 1 and 25 parts by weight of the ultraviolet absorber,
A tetrahydrofuran solution for a protective layer was prepared in the same manner as in Example 1, except that 1 to 10 parts by weight of 3,5-di-tert-butyl-4-hydroxytoluene was used in place of the antioxidant.

In addition, the above tetrahydrofuran solution for the protective layer was prepared in Example 1.
was coated on the photosensitive layer of the photoreceptor to produce an electrophotographic photoreceptor.

Comparative Example 5 Using 0 to 50 parts by weight of the ultraviolet absorber used in Example 8 above, a tetrahydrofuran solution for a protective layer containing only the ultraviolet absorber was prepared in the same manner as in Example 1, and
An electrophotographic photoreceptor was produced.

Comparative Example 6 Using 0 to 40 parts by weight of the antioxidant used in Example 8 above, a tetrahydrofuran solution for a protective layer containing only the antioxidant was prepared in the same manner as in Example 1. was created.

When the photoreceptor was examined for photodegradability using the test method described above, the results shown in FIG. 3 were obtained.

As is clear from FIG. 3, UV absorbers and antioxidants alone cannot prevent photodeterioration of the photoreceptor unless added in large amounts (see Comparative Examples 5 and 6). On the other hand, in Example 8 in which an ultraviolet absorber and an antioxidant were used in combination, it was found that photodeterioration of the photoreceptor could be prevented with a small amount added.

<Effects of the Invention> As described above, according to the electrophotographic photoreceptor of the present invention, since the protective layer contains an ultraviolet absorber and an antioxidant, photodeterioration of the photoreceptor can be prevented with a small amount of addition. The unique effect is that the photosensitive characteristics and electrical characteristics of the photoreceptor can be maintained over a long period of time without reducing the abrasion resistance of the photosensitive layer.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing the structure of the photoreceptor, respectively, and FIG. 3 is a diagram showing the results of Example 8, Comparative Example 5, and Comparative Example 6. (1) (11) Conductive substrate, (12) Charge transport layer, (13) Charge generation layer, (4) (14)
...Photosensitive layer, (5) (15)...Protective layer.

Claims (1)

[Claims] 1. Organic photoreceptor with a protective layer on the surface The protective layer contains UV absorbers and acids. A battery containing an anti-oxidation agent. Child photographic photoreceptor. 2. The protective layer is based on 100 parts by weight of the binder resin. and 5 to 40 parts by weight of ultraviolet absorber and Contains 1 to 10 parts by weight of antioxidant The electronic device according to claim 1 above is Child photographic photoreceptor. 3. The UV absorber is benzotriazole The above-mentioned claims are ultraviolet absorbers. The electrophotographic effect described in item 1 or 2 of the box below. Light body.