JPH03622B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor having a charge generation layer and a charge transfer layer, and particularly to the composition of the charge transfer layer. Photoreceptors used in electrophotography are generally single-layer types that have two functions of carrier generation and carrier transfer in one layer, such as selenium photoreceptors, selenium alloy photoreceptors, and ZnO photoreceptors, and polyvinyl carbazole to selenium photoreceptors. Laminated photoreceptor, oxadiazole ~ perylene pigment laminated photoreceptor, pyrazoline compound ~
There are two types of laminated type photoreceptors, such as azo pigment laminated photoreceptors, in which the two functions of carrier generation and carrier movement are separated into each layer. The electrophotographic process for any photoreceptor generally involves first uniformly charging the surface layer, then imagewise exposing the surface to form an electrostatic latent image, and applying colored powder (toner) to the surface of this latent image. ) and a carrier are brought into contact to visualize the image, and if necessary, the resulting image is transferred to transfer paper. In the case of a laminated photoreceptor, when charging and exposure are performed according to this process, the light passes through the charge transfer layer and reaches the charge generation layer, where both anode and cathode charges are generated. . Among these charges, the charges with the opposite polarity to the charges on the surface of the photoreceptor are attracted by the charges, move through the charge transfer layer, reach the surface, and are discharged and neutralized with the charges on that part. . On the other hand, the charges remaining in the charge generation layer are neutralized by being discharged with charges having the opposite polarity to the electrical charges in the conductive layer below the charge generation layer. Therefore, it goes without saying that the most important property of the laminated photoreceptor in these processes is photoconductivity, but electrophotographic processes also require various other processes that affect the photoreceptor, such as the development process and the transfer process. Therefore, the laminated photoreceptor must exhibit sufficiently satisfactory characteristics in these steps as well. By the way, in the electrophotographic process other than charging and exposure,
One of the biggest problems is the adhesion of toner to the surface of the photoreceptor, and the occurrence of wear and scratches when the developer or transfer paper comes into contact with the surface of the photoreceptor. These problems on the surface of the photoreceptor are mainly caused by the composition of the charge transfer layer, especially the properties of the binder, but the properties necessary for the binder to solve these problems are: (1) a tough film; (2) good compatibility with the coexisting charge transfer agent; (3) resistance to toner filming (residual toner adhesion); (4) excellent high voltage resistance; and (5) during application. Good solubility in the solvent used (6) Excellent water resistance (7) Transparency
(8) High insulation properties (9) Resistance to adhesion of insoluble materials during development, etc. All of these must be met. However, although there are some that satisfy these requirements to some extent, none satisfy all of them, and for this reason, the problems of toner adhesion, abrasion, and scratches on the surface layer of the laminated photoreceptor cannot be satisfactorily solved. An object of the present invention is to provide a laminated electrophotographic photoreceptor that hardly causes toner adhesion, wear, or scratches on the surface layer by using a binder that satisfies all of the above requirements (1) to (9). It is to be. That is, the photoreceptor of the present invention is an electrophotographic photoreceptor in which a charge generation layer containing a charge generation agent as a main component and a charge transfer layer containing a charge transfer agent and a binder as main components are sequentially provided on a conductive support. agent 50~150
5 parts by weight of acrylic or methacrylic acid ester homopolymer or copolymer as binder
30 parts by weight and 70 to 150 parts by weight of polyarylate. Among the binders used in the present invention, polyarylate is a resin that satisfies the above requirements to some extent. That is, this resin forms a relatively tough film and has excellent wear resistance. In addition, it has good compatibility with charge transfer agents, has high voltage resistance, and is also excellent in water resistance, transparency, and insulation properties, but is poor in toner filming properties. Therefore, in order to improve the toner filming properties of polyarylate resin, the present inventors conducted various studies on the use of polyarylate resin in combination with other resins. It has been found that the amount of filming can be greatly reduced and a stronger film can be formed. The present invention is based on such knowledge. Examples of the acrylic or methacrylic acid ester homopolymers or copolymers include those listed below. For example, polymethyl methacrylate, polyethyl methacrylate, poly-n-butyl methacrylate, poly-n-propyl methacrylate, polyethylene methacrylate, poly(2-ethylhexyl methacrylate), poly(n-hexyl methacrylate), polylauryl methacrylate, polyoctyl methacrylate, Poly(iso-butyl methacrylate), polytridecyl methacrylate, polystearyl methacrylate polymethoxyethyl methacrylate, poly-2-hydroxyethyl methacrylate, polydimethylaminoethyl methacrylate, polyglycidyl methacrylate, polyacrylic methacrylate, polyethyl acrylate, poly-n - Methacrylic acids such as butyl acrylate, polycyclohexyl acrylate, polybenzyl acrylate, poly-2-ethylhexyl acrylate, polydecyl acrylate, polystearyl acrylate, methoxyethyl acrylate, poly-1,4-butylene glycol monoacrylate, polyglycidyl acrylate, etc. Or an acrylic acid ester homopolymer may be mentioned. Furthermore, each of the monomers of these homopolymers was
Examples of copolymers in which two or more are copolymerized include methyl methacrylate: butyl methacrylate copolymer, ethyl acrylate: 2-hydroxyethyl acrylate copolymer, methoxyethyl methacrylate: ethyl acrylate copolymer, n-butyl methacrylate: n-butyl Acrylate copolymer, benzyl acrylate: butyl acrylate copolymer, 2-ethylhexyl acrylate:
Binary copolymers such as ethyl acrylate copolymer, glycidyl acrylate:ethyl acrylate copolymer, ternary copolymers such as n-butyl acrylate:ethyl acrylate:2-ethylhexyl acrylate, and even quaternary copolymers Combination can be mentioned. Copolymers of these acrylic or methacrylic acid ester monomers with other monomers can also be used. Other monomers include styrene, vinyl acetate,
Examples include methacrylic acid, acrylic acid, vinyl chloride, acrylonitrile, vinylimidazole, vinylpyridine, vinylpyrrolidone, and acrylamide. In particular, a copolymer of styrene and acrylic or methacrylic acid ester is preferable from the viewpoint of insulation properties and compatibility with polyarylate. Furthermore, among the above-mentioned acrylic or methacrylic esters, monopolymers or copolymers of monomers in which the ester has 4 or more carbon atoms gave good results in improving toner filming properties. These acrylic acid or methacrylic acid esters include n-butyl methacrylate, n
-butyl acrylate, iso-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, octyl methacrylate, lauryl methacrylate, ethoxy methacrylate, glycidyl methacrylate, stearyl methacrylate, n-butyl acrylate, cyclohexyl acrylate, Examples include decyl acrylate, stearyl acrylate, 1,4-butylene glycol monoacrylate, glycidyl acrylate, and the like. In the binder of the present invention, 5 to 30 parts by weight of an acrylic or methacrylic acid ester homopolymer or copolymer and 70 to 150 parts by weight of a polyarylate resin are used per 50 to 150 parts by weight of the charge transfer agent. If the amount of the acrylic or methacrylic acid ester alone or copolymer is less than 3 parts by weight, sufficient effects on toner filming properties will not be exhibited.
Further, when the amount of polyarylate resin exceeds 150 parts by weight, a similar tendency is exhibited, further resulting in a decrease in sensitivity (residual potential is not removed). On the other hand, when the amount of the acrylic or methacrylic acid ester alone or copolymer exceeds 30 parts by weight, the potential retention property and high voltage resistance are reduced. Furthermore, when the amount of polyarylate is less than 70 parts by weight, the potential holding property and high pressure resistance are deteriorated, and at the same time, the charge transfer agent is deposited on the surface of the photoreceptor or the photoreceptor surface becomes cloudy. As the charge transfer agent to be combined with the binder of the present invention as described above, any known electron-accepting substance or electron-donating substance can be used. First, electron-accepting substances include compounds with an electron-accepting core structure such as carboxylic acid anhydrides, ortho or paraquinoid structures, and aliphatic cyclic compounds having electron-accepting substituents such as nitro, nitroso, and cyano groups. compounds, aromatic compounds, heterocyclic compounds, etc. More specifically, maleic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetraprom phthalic anhydride, naphthalic anhydride, bilomellitic anhydride, chlor-P- Benzoquinone, 2,5-dichlorobenzoquinone, 2,6-
Dichlorobenzoquinone, 5,8-dichloronaphthoquinone, O-chloroanil, O-promuanil,
P-chloranyl, P-promanil, P-iodoanyl, tetracyanoquinodimethane, 5,6-
quinolinedione, coumarin-2,2-dione, oxindylpine oxindigo, 1,2-dinitroethane, 2,2-dinitropropane, iminodiacetonitrile, succinonitrile, tetracyanoethylene, 1,1,3, 3-tetracyanopropenide, O-, m- or P-dinitrobenzene, 1,2,3-trinitrobenzene, 1,2,
4-trinitrobenzene, 1,3,5-trinitrobenzene, dinitrobenzyl, 2,4-dinitroacetophenone, 2,4-dinitrotoluene, 1,3,5-trinitrobenzophenone,
1,2,3-trinitrobenzanisole, α,
β-dinitronaphthalene, 1,4,5,8-tetranitronaphthalene, 3,4,5-trinitro-
1,2-dimethylbenzene, 3-nitroso-2-
Nitrotoluene, 2-nitro-so-3,5-dinitrotoluene, O-m- or P-nitronitrosobenzene, phthalonitrile, terephthalonitrile, isophthalonitrile, benzoyl cyanide,
Promobenzyl dianide, quinoline cyanide, O-xylylene cyanide, O, m- or P-nitrobenzyl cyanide, 3,5-dinitropyridine,
3-nitro-2-pyridine, 3,4-dicyanopyridine, α-β-γ-cyanopyridine, 4,6-
Dinitroquinone, 4-nitroxanthone, 9,
10,-dinitroanthracene, 1-nitroanthracene, 2-nitrophenanthrenequinone, 2,
5-dinitrofluorenone, 2,6-dinitrofluorenone, 3,6-dinitrofluorenone,
2,7-dinitrofluorenone, 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, 3,6-dinitrofluorenone mandenonitrile, 3-nitrofluorenmandenonitrile, tetracyanobilene and so on. On the other hand, among charge transfer agents, electron-donating substances include alkyl groups such as methyl groups, alkoxy groups,
A compound containing at least one of an amino group, an imino group, and an imide group, or a polycyclic aromatic compound such as anthorcene, birene, phenanthrene, conene, etc. in the main chain or side chain, or indole, carbazole, oxazole, isoxazole, thiazole, There are compounds having nitrogen-containing cyclic compounds such as imidazole, pyrazole, oxadiazole, thiadiazole, triazole and their derivatives,
Specifically, low molecular weight ones include hexamethylene diamine, N-(4-aminobutyl)cadaverine, P-toluidine, 4-amino-O-xylene, N,N'-diphenyl-1,2-diaminoethane, O-, m- or P-ditolylamine, triphenylamine, duurene, 2-bromo-3,7
-dimethylnaphthalene, 2,3,5-trimethylnaphthalene, N'-(3-bromphenyl)-N-
(β-naphthyl)urea, N'-methyl-N-(α-
naphthyl) urea, N,N'-diethyl-N-(α-
naphthyl) urea, 2,6-dimethylanthracene, anthracene, 2-phenylanthracene,
9,10-diphenylanthracene, 9,9'-pianthranyl, 2-dimethylaminoanthracene,
phenanthrene, 9-aminophenanthrene,
3,6-dimethylphenanthrene, 5,7-dibromo-2-phenylindole, 2,3-dimethylindoline, 3-indolylmethylamine, carbazole, 2-methylcarbazole, N-ethylcarbazole, 9-phenyl enylcarbazole, N
-Ethylcarbazole, 1,1-dimethylidene-
9-ethylcarbazole, 3-(P-methoxyphenyl)oxazolidine, 3,4,5-trimethylisoxazole, 2-anilino-4,5-diphenylthiazole, 2-anilino-4,5-diphenylthiazole, 2,4,5-triaminophenyl imidazole, 4-amino-3,5-dimethyl-1-phenylpyrazole, 2,5-diphenyl-1,3,4-oxadiazole, 1,3,
5-triphenyl-1,2,4-triazole,
1-Amino-5-phenyltetrazole, bis-
Diethylaminophenyl-1,3,6-oxazole, 1,3-diphenyl-2-P-diethylaminophenyltetrahydroimidazole, bis[P-(N,N-dibenzyl)aminophenyl]methane, 1,1-bis[P -(N,N-dibenzyl)
Aminophenyl]propane, 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 4,4'-bis(diethylamino)-2,
2′-dimethyl-2″-chlorotriphenylmethane,
α,α-bis(2-methyl-4-diethylaminophenyl)-2-picoline, α,α-bis(2-
methyl-4-diethylaminophenyl)-2-methylefuran, α,α-bis(2-methyl-4-diethylaminophenyl)-2-methylpyrrole,
α,α-bis(2-methyl-4-diethylaminophenyl)-2-methylindole, α,α-bis(2-methyl-4-diethylaminophenyl)
-2-methylbenzothiophene, α,α-bis(2-methyl-4-diethylaminophenyl)-2
-methylbenzofuran, 4,4',4''-tris(diethylamino)-2,2'-dimethyltriphenylmethane, and high molecular weight ones such as poly-N-vinylcarbazole and its derivatives (e.g. carbazole bone core). halogens such as chlorine and bromine, and substituents such as methyl groups and amino groups), polyvinylbyrene, polyvinylanthracene, birene-formaldehyde condensation polymers, and derivatives thereof (for example, those having halogens such as bromine, and nitro groups in the birene core) etc.). Known charge generating agents and conductive supports used in the charge generating layer can be used as they are. That is, as charge generating agents, for example, selenium, Examples of inorganic pigments such as tellurium, cadmium sulfide, cadmium-selenium sulfide, and organic pigments include C-I Pigment Blue 25 (color index CI21180) and C-I Pigment Red 41.
(CI21200), CIA Dred 52
(CI45100), CI Basic Cred 3
(CI45210), Azo pigment with carbazole bone core (Patent application 1987-8740), Azo pigment with styrylstilbene bone core (Patent application 1988-48859), Azo pigment with triphenylamine bone core (Patent application 1987-8740) 52−
45812), azo pigments with dibenzothiophene bone cores (patent application 1986-86255), azo pigments with oxadiazole bone cores (patent application 1987-77125), azo pigments with fluorenone bone cores (patent application 1986-7712), 52-87351), azo pigment with bisstilbene bone core (patent application 1972-
81790), pigments with distyryl oxadiazole bone cores (Japanese Patent Application No. 1986-86711), azo pigments with distyrylcarbazole bone cores, phthacyanine pigments such as CI Pigment Blue 16 (CI74100), e.g. - Eyebutt Brown 5
(CI73410), indigo pigments such as Shea Butt Dye (CI73030), perylene pigments such as Argo Scarlet B (manufactured by Bayer AG), and Indance Scarlet R (manufactured by Bayer AG). Note that these charge generating agents can be used in combination with various binders and sensitizers, if necessary. In this case, the binder used is a condensation resin such as polyamide, polyurethane, polyester, epoxy resin, polyketone, or polycarbonate, or a vinyl polymer such as polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, or polyacrylic acid. Any resin with high insulation properties and adhesive properties can be used. In addition, as a sensitizer, brilliant green,
Victoria Blue B, Methyl Violet, Crystal Violet, Ash Violet,
Triallylmethane dyes such as 6B, Rhodamimi B, Rhodamine 6G, Rhodamine G extraeosin 8, erythrosine, rose bengal, xanthene dyes such as fluorescein, thiazine dyes such as methylene blue, cyanine dyes such as cyanine, 2,6 -diphenyl-4-(N,N
- dimethylaminophenyl), thiapyrylium perchlorate, penzopyrilium salt (Special Publication 1977-
Examples include biryllium dyes such as (described in 25658). As the conductive support, a metal plate such as aluminum, a plastic film on which metal such as aluminum is vapor-deposited or bonded, a cylinder, etc. are used. To make the photoreceptor of the present invention, a charge generating layer with a thickness of about 2 μm or less is formed by vapor depositing or sputtering a charge generating agent on a conductive support, or by coating and drying a solution or dispersion containing a charge generating agent. After the formation, a solution containing a predetermined amount of a charge transfer agent, an acrylic or methacrylic acid ester alone or a copolymer, and a polyarylate is applied thereon and dried to a thickness of 5.
A charge transport layer of ~25μ may be provided. In addition, the photoreceptor obtained in the above manner has the following properties:
An adhesive layer or barrier layer can be provided between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide,
Nitrocellulose, aluminum oxide, etc. are used, and the film thickness is preferably 1 μm or less. To perform copying using the photoreceptor of the present invention, the surface of the photoreceptor is charged, exposed, and developed, and if necessary, transferred to paper or the like. Examples are shown below. Note that all parts in this example are parts by weight. Example 1 1 part of a bisazo compound having the following structure was dispersed with a sand grinder along with 50 parts of cyclohexanone on a conductive support made of an 80 μm thick polyethylene terephthalate film laminated with a 10 μm thick aluminum foil, and a polyester resin was dispersed therein. A charge generation layer having a dry film thickness of 0.5 μm was provided by applying a solution in which 0.5 part of the charge was added and dissolved using a film applicator. Next, a solution having the following composition was applied onto this charge generation layer by a doctor blade method and dried to form a charge transfer layer having a thickness of 15 μm, thereby obtaining a laminated electrophotographic photoreceptor. 2,5-bis(P-diethylaminophenyl)
-1,3,4-oxadiazole 1 part polyarylate (Unitika U-100) 1 part poly-n-butyl methacrylate 0.2 parts tetrahydrofuran 15 parts For comparison, a solution without poly-n-butyl methacrylate was prepared using a doctor. Apply by blade method,
A dry charge transfer layer having a thickness of 15 μm was provided to obtain a laminated electrophotographic photoreceptor. Each photoreceptor thus obtained was tested for film strength, water resistance, compatibility, degree of adhesion of residual toner (toner filming), and charging characteristics. The test method was as follows. Film strength test Adjust the length of the photoreceptor to 10 cm in the coating direction and 5 cm in the vertical direction, and use it to create a cylinder with a diameter of 10/π cm. Place two of the tubes created in this way in parallel, place a glass plate (with a constant weight), and then place a weight on top of this to find the weight at which the film cracks in the photoreceptor's bending area occur. Ta. Water Resistance Test The photoreceptor was immersed in distilled water for 2 days, and its changes were examined. Compatibility Test Approximately 10 c.c. of the charge transfer layer liquid was taken, placed in a centrifuge, and centrifuged at approximately 5000 rpm for 10 minutes to examine the presence or absence of a separation phenomenon. Toner adhesion test On the inner wall of a cylindrical glass tube with a diameter of 3 cm and a volume of 30 c.c.
After pasting the weighed sample, completely stopper both sides of the tube with hard rubber, and add 5% by weight toner and 95% iron powder.
Add 20g of developer consisting of % by weight, place it on the stand of a ball mill, rotate it at 50 rpm for 2 days, then take out the sample with the developer attached, weigh the sample again, and calculate the amount per unit area at that time. The amount of increase in is defined as the toner adhesion amount. Charging characteristics test: Electrostatic copying paper tester SP-428 manufactured by Kawaguchi Electric Co., Ltd. was used to statically corona charge the paper at -6KV.
After being kept in a dark place for 10 seconds, it was exposed to light at an illuminance of 5 lux to examine the charging characteristics. The initial potential is Vo (-V), in the dark.
The potential holding rate for 10 seconds is V ₁₀ /V ₀ (%), and the illuminance required to reduce the initial potential to half is E 1/2 (lux・
sec). The results are shown in Table 1.

[Table] Examples 2 to 10 Similar experiments were carried out by adding the same amount of the following acrylic or methacrylic acid ester homopolymer instead of poly-n-butyl methacrylate in Example 1. The results are shown in Table 2 below.

[Table] From the results in Tables 1 and 2, it can be seen that film strength and toner adhesion are greatly improved by adding an acrylic or methacrylic acid ester homopolymer. Examples 11 to 15 First, the following composition was sufficiently ground in a ball mill.

[Table] Next, this pulverized mixture was taken out and diluted with 20 parts of tetrahydrofuran while stirring gently. This dispersion was placed on a polyethylene terephthalate film (thickness: 80μ) on which aluminum was vapor-deposited.
This solution was applied using a doctor blade with a wet gap of 35μ and dried at 80°C for 5 minutes to form a charge generation layer with a thickness of 0.4μ. Next, a solution having the following composition was applied onto this charge generation layer by a doctor blade method and dried at 100° C. for 10 minutes to form a charge transfer layer having a thickness of 15 μm, thereby obtaining a laminated electrophotographic photoreceptor. 4,4-bis(diethylamino)-2,2-dimethyltriphenylmethane 1 part polyarylate 1.2 parts acrylic ester copolymer (shown in Table 3)
0.2 parts Tetrahydrofuran 15 parts The thus prepared photoreceptor was tested for each item in the same manner as in Example 1. The results are shown in Table 3 below. Further, as Comparative Example 2, a similar test was conducted on a photoreceptor to which no acrylic ester copolymer was added.

[Table] Examples 16 to 20 Similar photoreceptors were prepared by adding the same amount of methacrylic ester copolymers shown in Table 4 instead of the acrylic ester copolymers of Examples 11 to 15, and similar photoreceptors were also prepared. The test was conducted and the results are shown in Table 4 below.

【table】

【table】

Claims (1)

[Scope of Claims] 1 Charge transfer in an electrophotographic photoreceptor in which a charge generation layer containing a charge generation agent as a main component and a charge transfer layer containing a charge transfer agent and a binder as main components are sequentially provided on a conductive support. For 50 to 150 parts by weight of the agent, 5 to 30 parts by weight of a single or copolymer of acrylic or methacrylic acid ester containing at least one ester having 4 or more carbon atoms and 70 to 150 parts by weight of polyarylate are used as a binder. An electrophotographic photoreceptor characterized by: 2. The electrophotographic photoreceptor according to claim 1, which is a copolymer containing styrene as a monomer of an acrylic or methacrylic acid ester copolymer.