JP2001288271A - Method for purifying polymer material having charge transporting ability and electrophotographic photoconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying a polymer material having charge transporting ability which has stable characteristics and provide an electrophotographic photoconductor having stable electrophotographic characteristics by using the polymer material having charge transporting ability treated by the purifying method. SOLUTION: The method for purifying a polymer material having charge transporting ability comprises mixing and stirring with water the polymer material having charge transporting ability which is dissolved in a water - immiscible organic solvent to separate a water phase and an organic phase and repeating water washing until an electrical conductance of the separated water phase attains the level of not more than 2 μS/cm. The electrophotographic photoconductor comprises the polymer material having charge transporting ability treated by the purifying method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transporting polymer material for an electrophotographic photoreceptor used in a copying machine, a printer, a facsimile, etc. The present invention relates to a method for purifying a charge transporting material used in an organic electronic device such as an EL element, and an electrophotographic photosensitive member containing a charge transporting polymer material purified by such a method.

[0002]

2. Description of the Related Art In recent years, organic photoconductors (OPCs) have been used in copiers,
Often used in printers. As a typical configuration example of an organic photoreceptor, a charge generation layer (CG) is formed on a conductive substrate.
L) and a laminated photoreceptor in which a charge transport layer (CTL) is sequentially laminated. The charge transport layer is made of a low molecular charge transport material (CT
M) and a binder resin. However,
The inclusion of the low-molecular charge transport material lowers the mechanical strength inherent in the binder resin, which causes abrasion, scratches, cracks, etc. of the photoreceptor, and impairs the durability of the photoreceptor. I have. Therefore, in order to improve the above-mentioned drawbacks of the laminated photoreceptor, a study has been made on a polymer material having a charge transporting ability (charge transporting polymer material). However, charge-transporting polymer materials are more susceptible to impurities than low-molecular-weight dispersing polymers, and high-purity materials are required to stabilize the electrical characteristics of electrophotographic photoreceptors from the beginning to long-term use. I have. Until now, purification of monomer raw materials, purification of chemicals used in the polymerization process, solvent cleaning after polymerization, alkali cleaning, acid cleaning, and cleaning with pure water have been performed. There is also known a method of repeating reprecipitation in which a solution dissolved in a good solvent is injected into a poor solvent. However, purification after polymerization is generally difficult compared to low molecular weight materials, and it is difficult to obtain a purified resin having stable characteristics, and often fails to satisfy electrophotographic characteristics when used for a photoreceptor. This has been a major obstacle to practical application.

[0003] As a conventional technique, there is known a method characterized by purifying a charge transporting resin by reprecipitation. (See Japanese Patent Application Laid-Open No. 9-59365) Although low molecular weight components can be removed by this method, it is difficult to completely remove impurities as a source of the resin from a resin that generates a residual potential by this method.

[0004] A method is also known in which a resin for an organic electronic device is dissolved in a solvent capable of dissolving and then brought into contact with an acidic substance or a basic substance for purification. (JP-A-9-593
The content is to remove impurities in the resin by contact with an acidic substance or a basic substance, and then remove the used acidic substance or the basic substance by washing with water. However, there is no specific description of the extent to which washing is performed. Further, when the organic phase and the aqueous phase are allowed to stand still by the method described in Examples, a long time is required, it is difficult to completely separate the organic phase and the aqueous phase, and there is a problem in production.

Further, in the charge transporting resin, the pH of the extract obtained by dissolving the charge transporting resin in an organic solvent and extracting the water-soluble component from the solution with distilled water is 0 to 0. .5 is also known. (See Japanese Patent Application Laid-Open No. 10-133405) However, although removing acidic components by washing with water is effective in stabilizing characteristics, complete stabilization of characteristics is not achieved by itself. The ionic species of the neutral component also affects the electrical characteristics. Further, the electric conductivity is described in the text, and a value of 2.3 to 4.01 μS / cm is described as an example. However, it has been found that such an electric conductivity is insufficient for improving the characteristics of the charge transporting resin.

[0006]

In view of such circumstances, the present invention has made intensive studies on a method for purifying a charge transporting polymer material having stable characteristics. Find out that impurities affect the fluctuation of characteristics, dissolve the charge transporting polymer material in an organic solvent that does not mix with water, mix and stir with water, and conduct the separated aqueous phase with a conductivity of 2 μS / cm or less. It has been found that a charge transporting polymer material having stable properties can be provided by repeating water washing until the electrophotographic photoreceptor has stable electrophotographic properties.

[0007]

The present invention comprises the following constitutions. (1) A charge transporting polymer material dissolved in an organic solvent that does not mix with water is mixed and stirred with water, and washing is repeated until the conductivity of the separated aqueous phase becomes 2 μS / cm or less. Method for purifying charge-transporting polymer materials.

(2) A method in which a solution in which a charge transporting polymer material is dissolved in an organic solvent immiscible with water is mixed and stirred with water, and thereafter, only the organic phase is separated to purify the charge transporting polymer material. The separation of the aqueous phase and the organic phase is accelerated by passing the mixed solution having insufficient separation after mixing and stirring once or more through a membrane having an average pore diameter of 200 μm or less, and the electric conductivity of the separated aqueous phase is 2 μS The method for purifying a charge-transporting polymer material comprises obtaining a charge-transporting polymer material by repeatedly washing with water until the charge-transporting polymer concentration reaches or less, and then removing the organic phase to remove the organic solvent.

(3) The charge transporting polymer material according to (1) or (2), wherein the charge transporting polymer material has a polycarbonate structure and / or a polyester structure and / or a polysilane structure. Purification method.

(4) An electrophotographic photoreceptor comprising a charge transporting polymer material processed by any of the purification methods described in (1) to (3) above.

(5) The charge transport layer of an electrophotographic photosensitive member comprising at least a charge generation layer and a charge transport layer laminated on a conductive substrate. An electrophotographic photoreceptor comprising a charge transporting polymer material purified by a method.

The charge transporting polymer material is dissolved in an organic solvent that is not mixed with water, mixed and stirred with water, and washed repeatedly with water until the conductivity of the separated aqueous phase becomes 2 μS / cm or less, thereby stabilizing the characteristics. The charge transporting polymer material can be provided.

In this case, the charge transporting polymer material is a material capable of transporting holes or electrons under an electric field without using a low molecular charge transport material, and a resin having such a function is particularly limited. Can be applied without. For example, polymer materials such as polycarbonate, polyester, polyurethane, polyether, polysiloxane, and acrylic resin having an arylamine skeleton, a benzidine skeleton, a hydrazone skeleton, a carbazole skeleton, a stilbene skeleton, and a pyrazoline skeleton, and a polymer material having a polysilane skeleton. And the like. Specific examples of the former include JP-A-01-001728, JP-A-01-00964,
JP-A-01-013061, JP-A-01-01904
9, JP-A-01-241559, JP-A-04-0116
27, JP-A-04-175337, JP-A-04-183
719, Japanese Unexamined Patent Application Publication No.
0767, JP-A-04-320420, JP-A-05-2
32727, JP-A-05-310904, JP-A-06-06
234836, JP-A-06-234837, JP-A-06
-234838, JP-A-06-234839, JP-A-Hei 0
6-234840, JP-A-06-238441, JP-A-06-239049, JP-A-06-236050, JP-A-06-236051, JP-A-06-295077, JP-A-07-056374, JP-A-08-176293,
JP-A-08-208820, JP-A-08-21164
0, JP-A-08-253568 and JP-A-08-2691
83, JP-A-09-062019, JP-A-09-043
883, JP-A-09-71642, JP-A-09-873
76, JP-A-09-104746, JP-A-09-110
974, JP-A-09-110977, JP-A-09-15
7378, JP-A-09-221544, JP-A-09-2
27669, JP-A-09-235367 and JP-A-09-235
241369, JP-A-09-268226, JP-A-09-09
-272735, JP-A-09-302084, JP-A-Heisei 0
Charge-transporting polymer materials described in JP-A-9-32085 and JP-A-09-328439. Specific examples of the latter include polysilylene polymers described in, for example, JP-A-63-285552, JP-A-05-19497, JP-A-05-70595, and JP-A-10-73944.

The organic solvent for dissolving the charge transporting polymer material is not particularly limited as long as it dissolves the polymer material and does not substantially mix with water. For example, any of hydrocarbons, esters, ethers, halides, acid amides, aldehydes, nitriles, ketones, aromatic nitro compounds, alkyl sulfoxides and the like may be used. Specifically, dichloromethane, 1,2-dichloroethane, 1,2-dichloroethylene, trichloroethane, tetrachloroethane, dichloropropane, chloroform,
Examples include toluene, xylene, ethylbenzene, chlorobenzene, dichlorobenzene, and ethyl acetate. Particularly, dichloromethane, toluene, chloroform and chlorobenzene are more preferably used. Further, the organic solvent can be used by mixing the above-mentioned solvents. Aliphatic hydrocarbons such as hexane, heptane and cyclohexane, which have poor solubility alone, can be used in combination with the above-mentioned solvents. The organic solvent is used in an amount of 2 to 200 parts by weight, preferably 3 to 100 parts by weight, based on 1 part by weight of the charge transporting polymer material. As the water to be used, distilled and / or ion-exchanged pure water having an electric conductivity of 2 μS / cm or less is preferably used. More preferably, pure water having an electric conductivity of 1 μS / cm or less is used. At the beginning of the water washing, water having higher conductivity may be used, and finally water having a conductivity of 2 μS / cm or less may be used. The amount of water used in one washing is not particularly limited, but is preferably 0.2 to 1 part by volume of the resin solution.
10 to 10 parts by volume, more preferably 0.5 to 3 parts by volume.

As the mixing and stirring, mechanical stirring by a stirring blade or stirring by a shaker can be applied, and it is preferable to stir so that the contact area between the organic phase and the aqueous phase is as large as possible. An in-line mixer or a homogenizer is preferably used. The temperature at the time of mixing may be lower than or equal to the boiling point of the organic solvent used and lower than or equal to 100 ° C. The mixing and stirring time varies depending on the stirring method, but is usually from 3 minutes to 300 minutes once, and preferably from 5 minutes to 30 minutes. After mixing and stirring, the organic phase and the aqueous phase are separated,
The conductivity of the aqueous phase is measured at 15 ° C. to 30 ° C. with a conductivity meter. If the conductivity is 2 μS / cm or less, the washing is terminated, but preferably the conductivity is 1.2 μS / cm or less. It is good to wash with water. Usually 0.7 to 1.2 μS / cm
To end. In order to more strictly compare the electric conductivities, the electric conductivity of the fractionated water after contacting a fixed concentration of the charge transporting polymer material solution with water at a predetermined ratio is measured. For example,
The conductivity of the fractionated water when a 5% by weight solution of the charge transporting polymer material is extracted with the same volume of water is measured.

If the conductivity is high, the organic phase is separated, fresh water is added and the above operation is repeated. After washing with water, the organic phase is separated, and the solvent is removed to obtain a purified product. Alternatively, there is a method in which an organic solvent is distilled off while a mixed state of an organic phase and an aqueous phase is kept. As a method for removing the solvent, a reprecipitation method, a spray drying method, a freeze drying method, or the like can be used. The amount of water finally remaining in the charge transporting polymer material is preferably 1,000 ppm or less, more preferably 300 ppm or less.

In addition to the above description, the purification can be more preferably performed by adding the following contents to the step of separating the organic phase and the aqueous phase.

When the organic phase in which the charge transporting polymer material is dissolved and the water are mixed and stirred vigorously, the mixture becomes an emulsion state or a suspension state, and the separation is incomplete even after standing, or the organic phase contains minute particles. Complete separation is impossible due to floating of water droplets, or a long time is required, thereby greatly reducing the washing efficiency. In addition, minute oil droplets float in the aqueous phase, which impairs the yield of the target product. It is effective to dilute the organic phase or to add a solvent such as alcohol soluble in both phases for these improvements, but it is necessary to increase the size of the purification device and complicate the labor for solvent recovery. Has the disadvantage of In order to separate the two phases without taking these measures, it is preferable to pass through a filter having an average pore size of 200 μm or less. The average pore size is preferably from 0.2 to 100 μm, more preferably from 1 to 50 μm. The material of the filter may be any material as long as it is insoluble in the solvent. Further, the above-mentioned filter subjected to a water repellent treatment with silicon or the like can also be used. However, a highly hydrophilic filter medium having a contact angle with water of 40 degrees or less is more preferable, and glass fiber is particularly preferable. On the other hand, as a method of passing through a filter, it may be performed in the same manner as ordinary filtration, under normal pressure, under pressure,
Either under reduced pressure may be used. Preferably, it is more efficient to carry out the treatment under pressure or under reduced pressure. The flow velocity when passing through the filter medium layer is about 100 mm / sec or less, preferably 10 mm / sec or less, and more preferably 1 mm / sec.
It is as follows.

In particular, when the charge transporting polymer material has a polycarbonate structure and / or a polyester structure and / or a polysilane structure, the conductivity of the aqueous phase is 2 μS /
It is effective to provide a charge-transporting polymer material having stable characteristics by washing with water until the thickness becomes equal to or less than 10 cm. It is presumed that impurities that greatly affect the properties are included in the impurities mixed in the resin synthesis stage, and it is necessary to remove the impurities to a level that is not affected by these.

Next, embodiments of the photoreceptor of the present invention will be described below. FIGS. 1 to 6 are cross-sectional views of the photosensitive member of the present invention.
Shown in The photoreceptor of the present invention comprises one or more aromatic polycarbonate resins as described above in the photosensitive layer 2 (2 ′,
2 '', 2 ''',2'''',2'''''), but depending on the manner of application of these, FIGS. 1, 2, 3, 4, and 5 5 or as shown in FIG.

The photoreceptor shown in FIG. 1 comprises a conductive support 1 on which a photosensitive layer 2 made of a sensitizing dye and an aromatic polycarbonate resin, and in some cases, a binder (binder resin) is provided. The aromatic polycarbonate resin here acts as a photoconductive substance, and the generation and movement of charge carriers required for light attenuation are performed through the aromatic polycarbonate resin. However, aromatic polycarbonate resins have almost no absorption in the visible region of light, and for the purpose of forming an image with visible light, sensitize by adding a sensitizing dye having absorption in the visible region. There is a need.

The photosensitive member shown in FIG. 2 is obtained by dispersing a charge generating substance 3 on a conductive support 1 in a charge transporting medium 4 comprising an aromatic polycarbonate resin having a charge transporting property alone or in combination with a binder. A layer 2 'is provided. The aromatic polycarbonate resin here forms a charge transport medium alone or in combination with a binder, while the charge generating substance 3 (a charge generating substance such as an inorganic or organic pigment) generates a charge carrier. In this case, the charge transport medium 4 is mainly responsible for receiving the charge carriers generated by the charge generating substance 3 and transporting them. In this photoreceptor, the basic condition is that the charge generation substance and the aromatic polycarbonate resin do not overlap each other mainly in the visible region in the absorption wavelength region. This is because light must be transmitted to the surface of the charge generation material 3 in order to efficiently generate charge carriers in the charge generation material 3. The aromatic polycarbonate resin containing the structural unit represented by the general formula (3), (4) or (6) has almost no absorption at a wavelength of 600 nm or more, and generally absorbs light in a visible region to a near infrared region, When combined with the charge generating substance 3 that generates charge carriers, it has a feature that it particularly effectively functions as a charge transporting substance. The charge transport medium 4 may contain a low molecular charge transport material.

The photoreceptor shown in FIG. 3 is obtained by stacking a charge generating layer 5 mainly composed of a charge generating substance 3 and a charge transporting layer 4 containing an aromatic polycarbonate resin having a charge transporting ability on a conductive support 1. Provided with a photosensitive layer 2 ″. In this photoreceptor, the light transmitted through the charge transport layer 4 reaches the charge generation layer 5, where charge carriers are generated, while the charge transport layer 4 receives charge carriers and transports them. The generation of charge carriers required for light attenuation is performed by the charge generation material 3, and the transport of charge carriers is performed by the charge transport layer 4. Such a mechanism is the same as that described for the photoconductor shown in FIG.

The charge transport layer 4 is formed by using the aromatic polycarbonate resin of the present invention alone or in combination with a binder. In order to increase the charge generation efficiency, the charge generation layer 5 may contain the aromatic polycarbonate resin of the present invention. For the same purpose, a low molecular charge transport material may be used in the photosensitive layer 2 ″. The photosensitive layer 2 '''to be described later
The same applies to 2 ″ ″ ′.

The photoreceptor in FIG. 4 has a protective layer 6 provided on the charge transport layer 4. In the case of this configuration, a protective layer is formed on the charge transport layer 4 in combination with the aromatic polycarbonate resin of the present invention or a binder. As a matter of course, formation on a low-molecular-weight dispersed charge transporting layer, which has been widely used, is effective. The photosensitive layer 2 'shown in FIG.
A protective layer may likewise be provided on the top.

The photosensitive member in FIG. 5 is the charge generating layer 5 in FIG.
Transport Layer 4 Containing Aromatic Polycarbonate Resin
And the mechanism of generation and transport of the charge carriers can be the same as described above. In this case, a protective layer 6 can be provided on the charge generation layer 5 as shown in FIG. 6 in consideration of mechanical strength.

In order to actually prepare the photoreceptor of the present invention, if the photoreceptor shown in FIG. 1 is used, one or more aromatic polycarbonate resins having charge transporting ability or a combination thereof with a binder are used. Then, a solution in which a sensitizing dye is added thereto is prepared, and the solution is coated on the conductive support 1 and dried to form the photosensitive layer 2.

The thickness of the photosensitive layer is 3 to 50 μm, preferably 5 to 40 μm. The amount of the aromatic polycarbonate resin in the photosensitive layer 2 is 30 to 100% by weight,
The amount of the sensitizing dye in the photosensitive layer 2 is 0.1 to 5% by weight, preferably 0.5 to 3% by weight. Examples of sensitizing charges include brilliant green, Victoria Blue B, methyl violet, crystal violet, triarylmethane dyes such as Acid Violet 6B, rhodamine B, rhodamine 6G, rhodamine G extra,
Examples include xanthene dyes such as eosin S, erythrosin, rose bengal and fluorescein, thiazine dyes such as methylene blue, and cyanine dyes such as cyanine.

In order to manufacture the photoreceptor shown in FIG.
One or two or more aromatic polycarbonate resins having a charge transporting ability or a binder are used in combination to disperse the fine particles of the charge generating substance 3 in a solution, which is coated on the conductive support 1 and dried. What is necessary is just to form the photosensitive layer 2 '.

The thickness of the photosensitive layer 2 'is 3 to 50 μm, preferably 5 to 40 μm. The amount of the aromatic polycarbonate resin having the charge transport ability in the photosensitive layer 2 'is 4
0 to 100% by weight, and the amount of the charge generating substance 3 in the photosensitive layer 2 'is 0.1 to 50% by weight, preferably 1 to 50% by weight.
20% by weight. Examples of the charge generating substance 3 include inorganic materials such as selenium, selenium-tellurium, cadmium sulfide, cadmium sulphide-selenium, and α-silicon, and examples of the organic material include CI Pigment Blue 25 (color index CI21180) and CI Pigment Red 41 ( CI2200), CIA Acid Red 5
2 (CI45100), sea eye basic red 3
(CI45210), azo pigments having a carbazole skeleton (described in JP-A-53-95033), azo pigments having a distyrylbenzene skeleton (JP-A-53-133)
445), an azo pigment having a triphenylamine skeleton (described in JP-A-53-132347), and an azo pigment having a dibenzothiophene skeleton (JP-A-54-2).
1728), an azo pigment having an oxadiazole skeleton (described in JP-A-54-12742),
Azo pigments having a fluorenone skeleton (JP-A-54-22)
834), azo pigments having a bisstilbene skeleton (described in JP-A-54-17733), azo pigments having a distyryloxadiazole skeleton (described in JP-A-54-2129), Azo pigments such as azo pigments having a distyrylcarbazole skeleton (described in JP-A-54-14967), for example, Sea Ivat Brown 5 (CI73410), Sea Iabut Dye (CI
No. 73030), Argo Scarlet B (manufactured by Bayer AG), Indance Scarlet R
(Manufactured by Bayer AG) and the like. As the phthalocyanine pigment, a compound having a phthalocyanine skeleton represented by the following formula, and M (central metal)
Represents a metal and a non-metal (hydrogen) element.

[0031]

Embedded image

M (center metal) mentioned here is H,
Li, Be, Na, Mg, Al, Si, K, Ca, S
c, Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, R
u, Rh, Pd, Ag, Cd, In, Sn, Sb, B
a, Hf, Ta, W, Re, Os, Ir, Pt, Au,
Hg, Tl, La, Ce, Pr, Nd, Pm, Sm, E
u, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
It is composed of a simple substance such as u, Th, Pa, U, Np, and Am, or two or more elements such as an oxide, a chloride, a fluoride, a hydroxide, and a bromide. The central metal is not limited to these elements. The charge generating substance having a phthalocyanine skeleton in the present invention is at least a compound represented by the general formula (N)
It is only necessary to have a basic skeleton as described above, and may have a multimeric structure such as a dimer or trimer, or may have a higher molecular structure. Further, those having various substituents in the basic skeleton may be used.

Of these various phthalocyanines, oxotitanium phthalocyanine having TiO as a central metal and non-metal phthalocyanine having H are particularly preferable in terms of photoreceptor characteristics.

It is also known that these phthalocyanines have various crystal systems. For example, oxotitanium phthalocyanine has α, β, γ, m, and y types, and copper phthalocyanine has α, β, It has a polymorphism such as γ. Even with phthalocyanines having the same central metal, various characteristics change as the crystal system changes. Among them, it has been reported that the photoreceptor characteristics also change with such a change in the crystal system. (Journal of the Institute of Electrophotography, Vol. 29, No. 4, 1990)
Each phthalocyanine has an optimal crystal system in terms of the photoreceptor characteristics. Particularly, in the case of oxotitanium phthalocyanine, a y-type crystal system is desirable.

Further, these charge generating substances may be a mixture of two or more kinds of charge generating substances having a phthalocyanine skeleton. Further, it may be mixed with other charge generating substances. In this case, examples of the charge transporting substance to be mixed include an inorganic material and an organic material.

In order to further manufacture the photoreceptor shown in FIG.
The charge generating substance is vacuum-deposited on the conductive support 1, or a dispersion liquid in which the fine particles 3 of the charge generating substance are dispersed in an appropriate solvent in which a binder is dissolved if necessary is applied and dried. If so, the surface is finished by a method such as buffing, the film thickness is adjusted, and the like, to form the charge generation layer 5, on which one or more aromatic polycarbonate resins or binders having charge transport ability are formed. The dissolved and used solution may be applied and dried to form the charge transport layer 4. Here, the charge generation material used for forming the charge generation layer 5 is the same as that described for the photosensitive layer 2 ′.

The thickness of the charge generation layer 5 is 5 μm or less, preferably 2 μm or less, and the thickness of the charge transport layer 4 is 3 to 50 μm.
μm, preferably 5 to 40 μm is suitable. In the case where the charge generating layer 5 is of a type in which the fine particles 3 of the charge generating layer material are dispersed in a binder, the ratio of the fine particles 3 of the charge generating material to the charge generating layer 5 is preferably 10 to 100% by weight. Is about 50 to 100% by weight. Further, the amount of the polycarbonate resin having the charge transport ability in the charge transport layer 4 is 40 to 100% by weight.

As described above, the photosensitive layer 2 '' in FIG. 3 may contain a low-molecular charge transport material. The charge transport material used here is as follows. . Oxazole derivatives and oxadiazole derivatives (JP-A-52-139065, 52-1)
No. 39066), imidazole derivatives, triphenylamine derivatives (described in JP-A-3-285960), benzidine derivatives (Japanese Patent Publication No. 58-32372).
), Α-phenylstilbene derivatives (described in JP-A-57-73075), and hydrazone derivatives (described in JP-A-55-154955 and 55-156954).
No. 55-52063 and No. 56-81850), and triphenylmethane derivatives (Japanese Patent Publication No. Sho.
1-110983), anthracene derivatives (described in JP-A-51-94829), and styryl derivatives (described in JP-A-56-29245 and 58-19804).
No. 3), carbazole derivatives (Japanese Unexamined Patent Publication No.
-585552), pyrene derivatives (Japanese Unexamined Patent Application Publication No.
-94812).

To produce the photoreceptor shown in FIG.
The protective layer 6 is provided by dissolving and coating the aromatic polycarbonate resin having the charge transporting ability of the present invention alone or in combination with a binder on the photoreceptor shown in FIG. The thickness of the protective layer is preferably from 0.15 to 10 μm. Protective layer 6
The amount of the aromatic polycarbonate resin of the present invention occupying therein is 40 to 100% by weight.

To prepare the photoreceptor shown in FIG. 5, a solution in which an aromatic polycarbonate resin having a charge transporting property or a binder is dissolved and used in combination with a binder is coated on the conductive support 1.
After drying to form the charge transport layer 4, a dispersion in which fine particles of a charge generation layer material are dispersed in a solvent in which a binder is dissolved as required is coated on the charge transport layer by a method such as spray coating and dried. Then, the charge generation layer 5 may be formed. The amount ratio of the charge generation layer or the charge transport layer is the same as that described in FIG.

By forming the above-mentioned protective layer 6 on the charge generation layer 5 of the photoreceptor thus obtained, FIG.
Can be prepared. In the production of any of these photoconductors, a metal plate or a metal foil such as aluminum, a plastic film on which a metal such as aluminum is deposited, or a paper subjected to a conductive treatment is used for the conductive support 1.

As the binder, condensed resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone and polycarbonate, and vinyl polymers such as polyvinylketone, polystyrene, poly-N-vinylcarbazole and polyacrylamide are used. But
All insulating and adhesive resins can be used. If necessary, a plasticizer is added to the binder. Examples of such a plasticizer include halogenated paraffin, dimethylnaphthalene, and dibutylphthalate. If necessary, additives such as an antioxidant, a light stabilizer, a heat stabilizer and a lubricant can be added.

The photoreceptor obtained as described above may be provided with an adhesive layer or a barrier layer between the conductive support and the photosensitive layer, if necessary. Materials used for these layers include polyamide, nitrocellulose, aluminum oxide, and titanium oxide.
m or less is preferable.

To make a copy using the photoreceptor of the present invention,
After the photosensitive surface is charged and exposed, development is performed and, if necessary, transfer to paper or the like. The photoconductor of the present invention has high sensitivity,
Also has excellent durability.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments. (Preparation Example 1 of Polymer Used) N- {4- [2,2-bis (4-hydroxyphenyl) vinyl] phenyl} -N, N-bis (4-tolyl) is used as a diol having charge transport ability.
2.69 parts of an amine, 1.97 parts of 2,2-bis (4-hydroxy-3-methylphenyl) propane as a copolymerized diol, and 0.024 parts of 4-tert-butylphenol as a molecular weight regulator were stirred and reacted. And a solution prepared by dissolving 2.66 parts of sodium hydroxide and 0.1 part of sodium hydrosulfite in 45 parts of water under a nitrogen stream was added and dissolved. Thereafter, the mixture was cooled to 7 ° C.
Bis (trichloromethyl) carbonate which is a monomer
A solution prepared by dissolving 16 parts in 40 parts of dichloromethane was added at a stretch with stirring, and then stirred for 15 minutes. After that, 0.01 parts of triethylamine was added, and the mixture was stirred and reacted at 27 ° C. for 60 minutes. Was synthesized. Then, dichloromethane is added to the charge-transporting polymer material 5%.
Of dichloromethane before purification was obtained in 100 parts. When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 52800 in number average molecular weight and 139800 in weight average molecular weight.

[0046]

Embedded image

Example 1 Distilled and ion-exchanged pure water (conductivity: 0.7 μS) was added to 100 parts of the polymer solution obtained in Production Example 1 of the used polymer.
/ Cm) and mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and both phases were separated. When this water washing treatment was performed four times, the conductivity of the separated aqueous phase was 1.96 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 2 100 parts of the polymer solution obtained in Production Example 1 of the used polymer was subjected to distillation and ion-exchanged pure water (with an electric conductivity of 0.7 μS).
/ Cm) and mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and both phases were separated. When this washing process was performed five times, the conductivity of the separated aqueous phase was 1.46 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 3 100 parts of a 3% aqueous sodium hydroxide solution was added to 100 parts of the polymer solution obtained in Production Example 1 of the used polymer, and the mixture was mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and the polymer solution phase was separated. Thereafter, pure water subjected to distillation and ion exchange treatment (conductivity 0.7 μS / cm) 10
0 parts were added and mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and both phases were separated. When this washing process was performed four times, the conductivity of the separated aqueous phase was 1.92 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 4 100 parts of a 3% aqueous sodium hydroxide solution was added to 100 parts of the polymer solution obtained in Production Example 1 of the used polymer, and the mixture was mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and the polymer solution phase was separated. Thereafter, 100 parts of a 2% hydrochloric acid aqueous solution was added, and the mixture was stirred with a shaker for 40 minutes. Thereafter, the mixture was allowed to stand for 20 minutes, and the polymer solution phase was separated. Thereafter, 100 parts of pure water (conductivity: 0.7 μS / cm) subjected to distillation and ion exchange treatment was added, and mixed and stirred by a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and both phases were separated. When this water washing treatment was performed three times, the conductivity of the separated aqueous phase was 1.35 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 5 Distilled and ion-exchanged pure water (conductivity: 0.7 μS) was added to 100 parts of the polymer solution obtained in Production Example 1 of the used polymer.
/ Cm) and mixed and stirred with a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and the polymer solution phase was separated. Thereafter, 100 parts of a 2% hydrochloric acid aqueous solution was added, and the mixture was stirred with a shaker for 40 minutes. Then 2
After standing for 0 minutes, the polymer solution phase was separated. Thereafter, 100 parts of pure water (conductivity: 0.7 μS / cm) was added, and mixed and stirred by a shaker for 15 minutes. Thereafter, the mixture was allowed to stand for 40 minutes, and both phases were separated. When this washing process was performed three times, the conductivity of the separated aqueous phase was 1.38 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Comparative Example 1 A charge transporting polymer material was obtained in the same manner as in Example 1, except that the pure water washing treatment was performed twice. The final conductivity of the separated aqueous phase was 11.75 μS / cm.

Comparative Example 2 A charge transporting polymer material was obtained in the same manner as in Example 1, except that the pure water washing treatment was performed three times. The final conductivity of the separated aqueous phase was 5.07 μS / cm.

Comparative Example 3 A charge transporting polymer material was obtained in the same manner as in Example 3 except that the pure water washing treatment was performed twice. The final conductivity of the separated aqueous phase was 9.82 μS / cm.

Comparative Example 4 A charge transporting polymer material was obtained in the same manner as in Example 4 except that the pure water washing treatment was performed twice. The final conductivity of the separated aqueous phase was 3.41 μS / cm.

Comparative Example 5 A charge transporting polymer material was obtained in the same manner as in Example 5, except that the final pure water washing treatment was performed twice. The final conductivity of the separated aqueous phase was 2.17 μS / cm.

(Production Example 2 of Polymer Used) As a diol having charge transporting ability, N- {4- [2,
2-bis (4-hydroxyphenyl) vinyl] phenyl}
2.7 parts of -N, N-bis (4-tolyl) amine, 1.99 parts of 1,1-bis (4-hydroxyphenyl) cyclohexane as a copolymerized diol and 4-tert-butylphenol 0 as a molecular weight regulator 0.023 part was placed in a stirred reaction vessel, and a solution prepared by dissolving 3.27 parts of sodium hydroxide and 0.1 part of sodium hydrosulfite in 33 parts of water was added thereto under a nitrogen stream. Thereafter, the mixture was cooled to 12 ° C., and a solution prepared by dissolving 2.31 parts of bis (trichloromethyl) carbonate, a trimer of phosgene, in 37 parts of dichloromethane was added at a stretch with stirring. Add 25 parts at 25 ° C
For 60 minutes. Thereafter, 0.02 parts of 4-tert-butylphenol was added, and the mixture was further stirred at 27 ° C. for 120 minutes to synthesize a charge transporting polymer material having the following structure. Thereafter, dichloromethane was added to obtain 100 parts of a pre-purification solution of 5% of the charge-transporting polymer material in dichloromethane.
When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 44200 in number average molecular weight and 16200 in weight average molecular weight.
0800.

[0058]

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Example 6 100 parts of the polymer solution obtained in Production Example 2 of the used polymer was subjected to distillation and ion-exchanged pure water (conductivity: 0.7 μS /
cm) and mixed and stirred with a shaker for 15 minutes. The mixed solution was passed through a 1000 mesh stainless steel filter under normal pressure, and then allowed to stand for 10 minutes to separate both phases. When this washing process was performed four times, the conductivity of the separated aqueous phase was 1.12 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 7 Distilled and ion-exchanged pure water (conductivity 0.07 μm) was added to 100 parts of the polymer solution obtained in Production Example 2 of the used polymer.
(S / cm) was added and mixed and stirred with a shaker for 15 minutes. After leaving still for 40 minutes, the polymer solution phase was separated. Thereafter, 100 parts of a 2% hydrochloric acid aqueous solution was added, and the mixture was stirred with a shaker for 40 minutes. Thereafter, the mixture was allowed to stand for 20 minutes, and the polymer solution phase was separated. Thereafter, 100 parts of pure water (conductivity: 0.7 μS / cm) was added, and the mixture was mixed and stirred by a homogenizer for 10 minutes. Then, the hole diameter 40μ
m through a glass fiber filter of 0.1 mm /
After passing through sec, the mixture was allowed to stand for 10 minutes, and both phases were separated. The conductivity of the separated aqueous phase was 0.90 μS / cm. Thereafter, the polymer solution was dropped into heated pure water to remove dichloromethane, and dried to obtain a charge transporting polymer material.

Example 8 A charge-transporting polymer material was obtained in the same manner as in Example 7, except that mixing with a homomixer and passing through a glass fiber filter were also applied to the first washing step and the aqueous hydrochloric acid washing step. . The conductivity of the final separated aqueous phase is 0.86
μS / cm.

Comparative Example 6 A charge transporting polymer material was purified in the same manner as in Example 6, except that a stainless steel filter was not used. In this case, the liquid separation after the water washing was not performed in the standing for 10 minutes, and the recovery of the charge transporting polymer material was reduced, and the conductivity of the fractionated water after four times was 3.82.

Comparative Example 7 A charge-transporting polymer material was purified in the same manner as in Example 7, except that the passing operation using a glass fiber filter was not performed. In this case, liquid separation after mixing by the homomixer was extremely poor, and it was not possible to separate the mixture by standing for 40 minutes.

Comparative Example 8 A charge-transporting polymer material was purified in the same manner as in Example 8, except that the passing operation using a glass fiber filter was not performed. In this case, liquid separation after mixing by the homomixer at the time of the first water washing was extremely poor, and it was not possible to separate the mixture by standing for 40 minutes.

(Production Example 3 of Polymer Used) As a diol having a charge transporting ability, N- {4- [1,1-bis (4-
After dissolving 4.86 parts of [hydroxyphenyl) ethyl] phenyl} -N, N-bis (4-tolyl) amine in 80 ml of a 2% aqueous solution of sodium hydroxide, the mixture was acid-cooled under a nitrogen stream with water cooling and vigorous stirring. 1.115 parts of terephthalic acid chloride and 1.11 parts of isophthalic acid chloride
A solution prepared by dissolving 5 parts in 60 ml of dehydrated chloroform was added and polymerized at 20 ° C. for 3 hours to synthesize a charge transporting polymer material having the following structure. Thereafter, chloroform is added to the solution to prepare a 5% solution of the charge-transporting polymer material 5% before chloroform purification.
0 parts were obtained. When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 15,400 in number average molecular weight and 26,900 in weight average molecular weight.

[0066]

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Example 9 The charge transporting polymer material was purified in the same manner as in Example 2 except that the polymer solution obtained in Production Example 3 of the used polymer was used. The conductivity of the final separated aqueous phase is 1.20
μS / cm. Thereafter, the polymer solution was dropped into a large amount of acetone to cause reprecipitation, filtered, and dried to obtain a charge transporting polymer material.

Comparative Example 9 A charge transporting polymer material was purified in the same manner as in Example 9, except that the water washing treatment was performed twice. The conductivity of the final fractionated aqueous phase was 4.01 μS / cm. Thereafter, the polymer solution was dropped into a large amount of acetone to cause reprecipitation, filtered, and dried to obtain a charge transporting polymer material.

Example 10 Phenylmethyldichlorosilane purified by distillation under reduced pressure was slowly added dropwise to refluxing dry toluene in which sodium metal was dispersed. After completion of the reaction, the mixture was passed through neutral alumina, washed once with water, and then reprecipitated with a large amount of methanol to obtain a crude product. The polymethylphenylsilane (weight average molecular weight 88,000) thus obtained was dissolved in toluene to prepare 100 parts of a 5% solution. The charge transporting polymer material was purified in the same manner as in Example 2 except that this polymer solution was used. The conductivity of the first fractionated aqueous phase was 11.2 μS / cm, and the conductivity of the final fractionated aqueous phase was 1.45 μS / cm. Thereafter, the polymer solution was dropped into a large amount of methanol to cause reprecipitation,
After filtration, the resultant was dried to obtain a charge transporting polymer material.

Example 11 (Photoreceptor preparation method 1) A polyamide resin (CM-8000:
The solution (made by Toray Industries, Inc.) was applied with a doctor blade and air-dried to provide a 0.3 μm intermediate layer. On this, a bisazo compound represented by the following formula as a charge generating substance is pulverized by a ball mill in a mixed solvent of cyclohexanone and 2-butanone, and the obtained dispersion is applied with a doctor blade,
It was air-dried to form a 0.5 μm charge generation layer.

[0071]

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Next, the charge-transporting polymer obtained in Example 1 as a charge-transporting polymer material was dissolved in dichloromethane, and this solution was applied on the charge-generating layer with a doctor blade and air-dried. Subsequently, the resultant was dried at 120 ° C. for 20 minutes to form a charge transporting layer having a thickness of 20 μm to prepare a photoreceptor.

(Evaluation of Initial Characteristics) The photoreceptor thus produced was subjected to a corona discharge of -6 KV for 20 seconds in a dark place using a commercially available electrostatic copying paper tester [EP-8200, manufactured by Kawaguchi Electric Works Ltd.]. After charging, the surface potential V _m (−V) of the photoreceptor was measured, and after being left in a dark place for another 20 seconds,
The surface potential V ₀ (−V) was measured, and the dark decay rate V ₀ / V _m was determined. Next, after irradiating with a tungsten lamp light for 30 seconds so that the illuminance on the photoreceptor surface was 5.31 lux, the residual potential V30 (−V) was measured. In addition, the initial potential 800
Time from V to potential halved by light irradiation (seconds)
And the exposure amount E _1/2 (lux · sec) was calculated.

(Charge Fatigue Characteristics Evaluation Method) After the initial characteristics were determined as described above, the device was allowed to stand at a discharge current of -28 μA for 15 minutes while irradiating light so that the exposure illuminance became 53 lux. Dark decay rate V
₀ / V _m, the residual potential V30 (-V), the exposure amount E _1/2 (lux · sec)
I asked. The results are shown in Table 1 together with Comparative Examples.

Examples 12 to 19 Photoconductors were prepared and evaluated in the same manner as in Example 11 except that the charge transporting polymers obtained in Examples 2 to 9 were used. Table 1 shows the results.

Example 20 A photoconductor was prepared and evaluated in the same manner as in Example 11 except that the charge transporting polymer obtained in Example 10 was used and tetrahydrofuran was used as a solvent instead of dichloromethane. Table 1 shows the results.

Comparative Examples 10 to 16 Photoconductors were prepared and evaluated in the same manner as in Example 11 except that the charge transporting polymers obtained in Comparative Examples 1 to 6 and Comparative Example 9 were used. Table 1 shows the results.

Comparative Example 17 A photoconductor was prepared and evaluated in the same manner as in Example 11, except that polymethylphenylsilane that had not been subjected to purification treatment was used, and tetrahydrofuran was used as a solvent instead of dichloromethane. Table 1 shows the results.

[0079]

[Table 1]

[0080]

As can be seen from the above results, when the charge transporting polymer material washed with water until the electric conductivity of the separated water becomes 2 μS / cm or less is used, the charge transporting material exhibiting a higher electric conductivity is used. The charge decay rate and the dark decay rate show the stability of the charge compared with the case of using the conductive polymer material, and the residual potential has stable and good characteristics in both the initial evaluation and the evaluation after fatigue. It can be seen that this method is effective as a purification method. Further, it can be seen that the electrophotographic photoreceptor using the thus-treated charge transporting polymer material has good initial characteristics and excellent durability.

Further, by mixing and stirring a solution in which a charge transporting polymer material is dissolved and water and passing the solution through a membrane having an average pore diameter of 200 μm or less, the liquid separation property can be improved, and the conductivity is 2 μS. / Cm or less, and the number of times and time required for the washing can be reduced, so that a charge transporting polymer material having excellent characteristics can be efficiently produced. By using the thus obtained charge transporting polymer material, the chargeability and its stability are excellent, the residual potential and its change are small, the electrical characteristics are excellent, and the charge transporting polymer material has It is possible to provide an electrophotographic photosensitive member having high mechanical strength and excellent wear resistance.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a layer configuration of an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a cross-sectional view showing another example of the layer configuration of the electrophotographic photoreceptor according to the present invention.

FIG. 3 is a cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present invention.

FIG. 4 is a cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present invention.

FIG. 5 is a cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present invention.

FIG. 6 is a cross-sectional view showing another example of the layer configuration of the electrophotographic photosensitive member according to the present invention.

[Explanation of symbols]

1 conductive support 2,2 ', 2'',2''', 2 '''',
2 '''''' photosensitive layer 3 charge generating substance 4 charge transport layer or charge transport medium 5 charge generation layer 6 protective layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaomi Sasaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Shinichi Kawamura 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Lee Hongkook 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh Company (72) Susumu Suzuka 66-2 Horikawa-cho, Sai-ku, Kawasaki City, Kanagawa Prefecture Hodoya Chemical Industry Co., Ltd. In-house (72) Inventor Katsuhiro Morooka 66-2 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa F-term (reference) 2H068 AA20 AA32 AA35 BB25 BB33 BB44 EA05 FA03 FA12 FA19 4J029 AA03 AA09 AB04 AC01 AC02 AE04 BB13B BD09A BH01 CB05A CB06A DA02 HA01 HB05 HC02 JB192 JD05 KH05 4J031 CC05 4J035 BA02 CA01K EB08

Claims (5)

[Claims] 1. A method in which a charge transporting polymer material dissolved in an organic solvent immiscible with water is mixed and stirred with water, and washing with water is repeated until the conductivity of the separated aqueous phase becomes 2 μS / cm or less. A method for purifying a charge-transporting polymer material characterized by the following. 2. A method for purifying a charge-transporting polymer material by mixing and stirring a solution in which a charge-transporting polymer material is dissolved in an organic solvent immiscible with water, together with water, and then separating only an organic phase. The separation of the aqueous phase and the organic phase is accelerated by passing the mixed solution having insufficient separation after mixing and stirring once or more through a membrane having an average pore diameter of 200 μm or less, and the electric conductivity of the separated aqueous phase is 2 μS / A method for purifying a charge-transporting polymer material, characterized by obtaining a charge-transporting polymer material by repeatedly washing with water until the thickness becomes equal to or less than 10 cm, and then removing the organic phase and removing the organic solvent. 3. The method for purifying a charge-transporting polymer material according to claim 1, wherein the charge-transporting polymer material has a polycarbonate structure and / or a polyester structure and / or a polysilane structure. 4. An electrophotographic photoreceptor comprising a charge-transporting polymer material processed by any of the purification methods described in claim 1. 5. An electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated on a conductive substrate, wherein the charge transport layer has a charge purified by the method according to claim 1. An electrophotographic photoreceptor comprising a transportable polymer material.