JP2001013698A - Method for purifying polymer material for electrophotographic photoreceptor, and electrophotographic photoreceptor. - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer material not containing impurities which deteriorate the characteristics of a photoreceptor and less liable to generate residual potential and to make obtainable an electrophotographic photoreceptor having good electrification ability, ensuring low residual potential and excellent in sensitivity and durability by dissolving a polymer material for an electrophotographic photoreceptor in an organic solvent and bringing the resulting solution into contact with activated clay. SOLUTION: A polymer material for an electrophotographic photoreceptor is dissolved in an organic solvent, powdery or granular activated clay is added to the resulting solution, stirred and separated by filtration and then the solvent is removed. Preferably the polymer material is dissolved in an organic solvent having a dielectric constant of <=8 and the resulting solution is brought into contact with the activated clay at a temp. of >=65 deg.C. The improvement of characteristics is attained at a treatment temperature of >=65 deg.C, and since impurities have high polarity, an apolar solvent produces a significant effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer material for an electrophotographic photoreceptor used for a copying machine, a printer, a facsimile, etc., particularly a polymer material used for a charge transport layer. The present invention relates to a method for purifying a charge-transporting polymer material to be used, and an electrophotographic photoreceptor containing the polymer material purified by those methods.

[0002]

2. Description of the Related Art A high-purity material is required for an electrophotographic photosensitive member in order to stabilize electrical characteristics from an early stage to after a long use. Among them, for polymer materials, purification of monomer raw materials, purification of chemicals used in the polymerization process, solvent washing after polymerization, alkali washing, acid washing, washing with pure water, and the like are 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, it is generally difficult to purify the polymer after it has been polymerized as compared with a low-molecular material, and the electrophotographic characteristics often cannot be satisfied. Particularly, in the case of a polymer material used for the charge transport layer of the photoreceptor, a trace amount of impurities affects the charge transport ability to generate a residual potential of the photoreceptor, cause a decrease in sensitivity, and change the charging characteristics. Or In particular, when a charge-transporting polymer material having a charge-transporting ability is used for the charge-transporting layer, the effect becomes more remarkable. As described above, it has been difficult to stably satisfy the electric characteristics by the conventional refining method.

For example, Japanese Patent Application Laid-Open No. 9-59365 discloses a method for purifying a charge-transporting resin by reprecipitation. This method can remove low-molecular-weight components, but may cause residual potential. It is difficult to completely remove impurities as a source from such a resin by this method. Also, Japanese Patent Application Laid-Open No. 9-59389 discloses a method in which a resin for an organic electronic device is dissolved in a solvent capable of being dissolved, and the resin is contacted with an acidic substance or a basic substance for purification. The use of activated clay is also mentioned as an example of the acidic substance, but there is no description of the example, and no description is given of the difference from other acidic substances. JP-A-7-56365 discloses a method for purifying a charge transport material for an electrophotographic photoreceptor using activated clay and / or activated carbon, which relates to a low molecular charge transport material and its raw material. However, there is no mention of a polymer material. Processing temperature is also 20-60 ° C
This is what is described in the context of low molecular weight materials.

[0004]

SUMMARY OF THE INVENTION A high-purity photoreceptor which does not contain impurities that degrade the photoreceptor characteristics in a polymer material used for an electrophotographic photoreceptor, and in particular, generates little residual potential. The present invention provides an electrophotographic photoreceptor having good chargeability, low residual potential, excellent sensitivity, and little change in characteristics upon fatigue, and excellent durability.

[0005]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention provides a method for mass-producing a polymer material for a photoreceptor.
As a result of intensive studies on methods that can satisfy the electrical characteristics, it has been found that the method of adsorption treatment using activated clay improves the electrical characteristics. Furthermore, it has been found that this method shows a good effect on a polymer material for a charge transport layer of a photoreceptor. Furthermore, it has been found that the charge transporting polymer exhibits a good effect.

According to a first aspect of the present invention, a polymer material for an electrophotographic photosensitive member is dissolved in an organic solvent, and the solution is contacted with activated clay. Is the law.

A polymer material for an electrophotographic photosensitive member has a molecular weight of 2000 among components from a support to a surface layer.
It refers to the above organic polymer materials. Specifically, a thermoplastic resin used as a binder in the charge transport layer or a charge transporting polymer material having both a binder function and a charge transport function, or a thermoplastic resin used as a protective layer,
Examples include thermoplastic resins used as binders in the charge generation layer, and organic polymer materials added to those layers. These may be dissolved in a soluble solvent, powdered or granular activated clay may be added and stirred, then separated by filtration, and the solvent may be removed.

As the activated clay, those generally produced can be used. For example, activated clay which is manufactured and sold by Japan Activated Clay Co., Ltd. or Mizusawa Chemical Industry Co., Ltd. can be used. There are various varieties of these, depending on the water content, fineness, degree of free acid, apparent specific gravity, etc., and any of them can be used. In general, powdered activated clay has a moisture content of 12% or less or 5% or less, a fineness of 80% or more when passed through a 200 mesh, a free acid of 2.5 mg KOH / g or less, and an apparent specific gravity of 0.40 to 0.80. Are preferably used. In addition, moisture is 12 as granular activated clay.
15-30 mesh, 30-60 at less than 5% or 5%
Mesh, fineness of 8 to 16 mesh, free acid of 2.5 mg KOH / g or less and apparent specific gravity of 0.50
~ 0.80 are preferably used. In addition, clay mineral acid clay such as montmorillonite and halloysite which are also used as a raw material of activated clay can be used. However, the activated clay has an excellent effect of removing impurities.

As a treatment method, in the case of a powdery product, purification may be performed by mixing and stirring with a liquid in which a polymer material is dissolved, and then contacting the liquid, and the liquid and waste clay may be separated by a filter. Further, the granular product can be purified by filling it in an adsorption tower, passing through and contacting a liquid in which a polymer material is dissolved.

[0010] The treatment temperature can be arbitrarily selected from 0 ° C to 300 ° C, but is preferably from 0 ° C to 200 ° C. The contact time can be arbitrarily selected, but is generally preferably 5 minutes or more. Further, it is preferably 10 minutes or more and 300 minutes or less. If the contact time is too short, the effect will not be exhibited, and if it is too long, side effects such as breaking of the polymer chain will occur, causing deterioration of the polymer itself. In particular, when the processing temperature is 60 ° C. or more, the contact time is 10
The time is preferably from 180 minutes to 180 minutes.

The filtration after the contact may be performed after cooling or at a high temperature. However, since the viscosity of the polymer solution is high,
It is more efficient to perform at a high temperature as long as the solvent and equipment allow. There is no particular limitation on the soluble solvent as long as it can dissolve the polymer material. For example, hydrocarbons, esters,
It may be any of ethers, halides, alcohols, acid amides, aldehydes, nitriles, ketones, aromatic nitro compounds, alkyl sulfoxides and the like.

According to the present invention, an aqueous solution of hydrochloric acid, silica gel or acidic alumina, which has been cited as an acidic substance in the prior art, was examined. could not. Therefore, the effect of the present invention is not due to the refining effect as an acidic substance, but to the inherent effect of activated clay.

According to a second aspect of the present invention, a polymer material for an electrophotographic photosensitive member is dissolved in an organic solvent, and the solution is contacted with activated clay at a temperature of 65 ° C. or higher. This is a method for purifying molecular materials.

According to the processing method of the first aspect, some impurities can be removed, but a large improvement effect cannot be expected even if the processing is performed for a long time. At a temperature near room temperature, even if the contact is made for a long time, repeatedly, and even if the amount of activated clay is increased, no improvement beyond the initial effect is observed. Rather, the electrical characteristics often deteriorate.
However, by setting the processing temperature to 65 ° C. or higher, it is possible to further improve characteristics that could not be achieved near room temperature. The treatment temperature is preferably from 65C to 200C, more preferably from 70C to 150C.

The invention according to claim 3 is characterized in that a polymer material for an electrophotographic photosensitive member is dissolved in an organic solvent having a dielectric constant of 8 or less, and the solution is contacted with activated clay at 65 ° C. or more. This is a method for purifying polymer materials for photographic photoreceptors.

In the purification using activated clay, it is expected that impurities that have been mixed in from the monomer when synthesizing the polymer material or impurities that have been mixed in during the polymerization are removed by physical adsorption and chemical adsorption. Expected to be a strong substance. Therefore, a non-polar solvent that dissolves the polymer material is as effective as possible. Specifically, a solvent having a dielectric constant of 8 or less at 20 ° C. or 25 ° C. is preferable. Further, considering the processing temperature, those having a boiling point of 65 ° C. or more under normal pressure are preferable.

Examples of the solvent having a dielectric constant of 8 or less include toluene, tetrahydrofuran, ethyl acetate, chloroform, and the like. Further, the solvent which satisfies the condition of a boiling point of 65 ° C. or more includes, for example, toluene, tetrahydrofuran, acetic acid and the like. Ethyl and the like.

According to a fourth aspect of the present invention, there is provided the electrophotographic apparatus according to the first or second or third aspect, wherein the polymer material for the electrophotographic photosensitive member is a polymer material used for the charge transport layer. This is a method for purifying a polymer material for a photoreceptor.

As the polymer material used for the charge transport layer, a binder resin used for dispersing a low-molecular charge transport material is mainly used. Specifically, polycarbonate, polyester, polyarylene, polyurethane, polystyrene, epoxy resin, methacrylic resin, acrylic resin, polyethylene, vinyl chloride resin, vinyl acetate resin, phenolic resin, polyvinylidene chloride, polysilane, silicon resin, polyvinyl butyral, Polyvinyl formal, polyacrylamide, phenoxy resin,
Alkyd resin, polyvinyl carbazole and the like can be mentioned. In addition, the present invention can be applied to a polymer material, a silicone oil, and the like which are used as additives such as a plasticizer, a leveling agent, and an antioxidant contained in the charge transporting layer, instead of the binder.

The invention of claim 5 is the case where the polymer material for the electrophotographic photosensitive member is a charge transporting polymer material used for the charge transport layer.
A method for purifying a polymer material for an electrophotographic photosensitive member according to the above.

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 any resin having such a function can be used without any particular limitation. . 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. A specific example of the former is disclosed in JP-A-01-00172.
8, JP 01-009964, JP 01-013061, JP 01-01
9049, JP 01-241559, JP 04-011627, JP 04
-175337, JP 04-183719, JP 04-225014, JP 04-230767, JP 04-320420, JP 05-232727,
JP 05-310904, JP 06-234836, JP 06-2348
37, JP-A-06-234838, JP-A-06-234839, JP-A-06-348
234840, JP 06-234841, JP 06-239049, JP
06-236050, JP 06-236051, JP 06-295077, JP 07-056374, JP 08-176293, JP 08-20882
0, JP 08-211640, JP 08-253568, JP 08-2
69183, JP 09-062019, JP 09-043883, JP 0
9-71642, JP-A-09-87376, JP-A-09-104746, JP-A-09-110974, JP-A-09-110976, JP-A-09-157378,
JP-A-09-221544, JP-A-09-227669, JP-A-09-2353
67, JP-A-09-241369, JP-A-09-268226, JP-A-09-268
272735, JP-A-09-302084, JP-A-09-302085, JP-A-09-302085
And a charge transporting polymer material described in JP-A-09-328539. As a specific example of the latter, for example,
285552, JP-A-05-19497, JP-A-05-70595 and the like are exemplified.

According to a sixth aspect of the present invention, there is provided an electrophotographic photosensitive member containing a polymer material which has been treated by any of the purification methods described in the first to fifth aspects. The subject electrophotographic photoreceptor is provided with a photosensitive layer on a conductive support, the photosensitive layer is divided into a charge generation layer and a charge transport layer,
All known organic electrophotographic photoreceptors, such as those having a protective layer provided on the surface of the photosensitive layer.

[0023]

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 having the following structure as a diol having charge transporting ability
2.69 parts of N-bis (4-tolyl) amine, 1.97 parts of 2,2-bis (4-hydroxy-3-methylphenyl) propane as a copolymerized diol, and 4-tert-butylphenol as a molecular weight regulator 0.024 parts was placed in a stirred reaction vessel, and sodium hydroxide 2.6 was added under a nitrogen stream.
6 parts and 0.1 part of sodium hydrosulfite in water 4
The solution dissolved in 5 parts was added and dissolved. Then 7 ° C
And 2.16 parts of bis (trichloromethyl) carbonate, a trimer of phosgene, were added to dichloromethane 40
The solution dissolved in the part is added all at once with stirring, and then
After stirring for 5 minutes, 0.01 part of triethylamine was added and 2 parts were added.
The mixture was stirred and reacted at 7 ° C. for 60 minutes. Thereafter, 40 parts of dichloromethane was added, and the organic layer was separated. After washing the organic layer with water, the insoluble matter is removed by filtration, and further washed twice with water.
Thereafter, the substrate was washed with a 2% aqueous hydrochloric acid solution, and finally, washed three times with water. The organic layer was dropped into a large amount of methanol to precipitate a yellow polycarbonate resin, thereby obtaining 4.48 parts of a random copolymer polycarbonate resin shown below. 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 13980 in weight average molecular weight.
It was 0.

[0024]

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(Preparation Example 2 of Polymer Used) As a diol having charge transporting ability, N- {4-
2.7 parts of [2,2-bis (4-hydroxyphenyl) vinyl] phenyl} -N, N-bis (4-tolyl) amine and 1,1-bis (4-hydroxyphenyl) cyclohexane as a copolymerized diol 1.99 parts and 0.023 part of 4-tert-butylphenol as a molecular weight regulator were placed in a stirred reaction vessel, and 3.27 parts of sodium hydroxide and 0.1 part of sodium hydrosulfite were added to 33 parts of water under a nitrogen stream. Was added and dissolved. 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. 01
The reaction was stirred at 25 ° C. for 60 minutes. Then 4
0.02 parts of -tert-butylphenol was added, and the mixture was further stirred and reacted at 27 ° C for 120 minutes. Thereafter, 37 parts of dichloromethane was added, and the organic layer was separated. The organic layer was washed with a 3% aqueous solution of sodium hydroxide, water, and a 2% aqueous solution of hydrochloric acid in that order, and further three times with water. The organic layer was dropped into a large amount of methanol to precipitate a yellow polycarbonate resin, thereby obtaining the following random copolymerized polycarbonate resin (4.81 parts). When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 44 as a number average molecular weight.
200 and weight average molecular weight was 160,800.

[0026]

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(Production Example 3 of Polymer Used) A charge-transporting polymer resin was obtained in the same manner as in Production Example 1 except that phosgene was used instead of bis (trichloromethyl) carbonate. When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 35,000 in number average molecular weight and 1 in weight average molecular weight.
48600. (Production Example 4 of used polymer)
Using 0.016 parts of rt-butylphenol, adding triethylamine and performing a stirring reaction at 27 ° C. for 60 minutes, then adding 0.02 parts of 4-tert-butylphenol again and performing a stirring reaction at 27 ° C. for 120 minutes. Similarly, the same random copolymer polycarbonate resin as that of Production Example 1 was obtained. When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 34900 in number average molecular weight and 85400 in weight average molecular weight. (Production Example 5 of used polymer) 1,1- as a monomer
Bis (4-hydroxyphenyl) cyclohexane 5.3
7 parts and 0.03 part of 4-tert-butylphenol as a molecular weight regulator were put into a stirred reaction vessel, and 3.2 parts of sodium hydroxide and 0.02 parts of sodium hydrosulfite were dissolved in 60 parts of water under a nitrogen stream. The solution was added and dissolved by heating. Thereafter, the mixture was cooled to 9 ° C.
2. bis (trichloromethyl) carbonate, which is a monomer
A solution prepared by dissolving 56 parts in 53.2 parts of dichloromethane was added dropwise with stirring. After stirring for 15 minutes, 0.8 parts of sodium hydroxide was added, and 10 minutes later, 0.01 parts of triethylamine was added. The mixture was stirred and reacted at 60 ° C. for 60 minutes. Then, 4-tert-butylphenol 0.03
The reaction mixture was further stirred at 30 ° C. for 60 minutes. Thereafter, 300 parts of dichloromethane was added, and the organic layer was separated. The organic layer is washed with a 5% aqueous sodium hydroxide solution, then three times with a 2% aqueous hydrochloric acid solution, and further washed with water for 4 times.
Washed twice. The organic layer was dropped into a large amount of methanol to precipitate a colorless polycarbonate resin, thereby obtaining 5.77 parts of a polycarbonate Z having the following structure. When the molecular weight of this product was measured by gel permeation chromatography, the molecular weight in terms of polystyrene was 57100 in number average molecular weight and 119900 in weight average molecular weight.

[0028]

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Example 1 One part of the polymer obtained in Production Example 1 was dissolved in 40 parts of dichloromethane (dielectric constant: 9.1), and 0.2 parts of activated clay (manufactured by Kanto Chemical Co., Ltd.) was added. After stirring for 30 minutes,
After filtration and separation, washing with water twice, a dichloromethane solution was dropped into a large amount of methanol to precipitate a polymer, which was separated and dried to obtain an activated clay treated product. Using this product, a photoreceptor was prepared in the following procedure. (Photoreceptor Production Method 1) A polyamide resin (CM-800) dissolved in a methanol / butanol mixed solvent on an aluminum plate
0: manufactured by Toray Industries Co., Ltd.) solution was applied with a doctor blade and air-dried to form a 0.3 μm intermediate layer. On this, a bisazo compound represented by the following formula as a charge generating material was pulverized by a ball mill in a mixed solvent of cyclohexanone and 2-butanone, and the obtained dispersion was applied with a doctor blade, air-dried, and then 0.5 μm Was formed.

[0030]

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Next, the above treated product as a charge transporting polymer material is dissolved in dichloromethane, and this solution is applied on the charge generation layer with a doctor blade, air-dried, and then dried at 120 ° C. for 20 minutes. A 20 μm-thick charge transport layer was formed to prepare a photoreceptor. (Evaluation of initial characteristics) A commercially available electrostatic copying paper tester [SP manufactured by Kawaguchi Electric Works, Ltd.]
428 type] and a corona discharge of -6 KV in a dark place for 20 times.
After charging for 2 seconds, the surface potential V _m of the photoreceptor (−
V) was measured and left in a dark place for further 20 seconds, and then the surface potential V ₀ (−V) was measured. Next, a tungsten lamp light was applied to the photosensitive member so that the illuminance on the surface of the photosensitive member became 5.3 lux.
After irradiation for 0 seconds, the residual potential V ₃₀ (−V) was measured, and at the same time, the time (second) until V ₀ became １ ／ was obtained, and the exposure amount E _1/2 (lux · sec) was calculated. . (Evaluation Method of Charge Fatigue Characteristics) 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. Similarly, the surface potential V _m (−V),
The surface potential V ₀ (−V), the residual potential V ₃₀ (−V), and the exposure amount E _1/2 (lux · sec) were determined.

The results are shown in Table 1 together with Comparative Examples. Comparative Example 1 A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the charge transporting polymer material obtained in Production Example 1 was used as it was. Comparative Example 2 One part of the charge-transporting polymer material obtained in Production Example 1 was dissolved in 35 parts of tetrahydrofuran, heated under reflux for 3 hours, and then reprecipitated by dropping into a large amount of methanol for precipitation. . A photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the material subjected to this treatment was used.

[0033]

[Table 1]

As can be seen from the above results, when the charge-transporting polymer material treated with activated clay was used, the residual potential was lower in the initial evaluation and after fatigue than in the case of only acid washing or repeated reprecipitation. It can be seen that the evaluation is small, and that the method is effective as a method for purifying a polymer material for an electrophotographic photosensitive member. Further, it can be seen that the electrophotographic photoreceptor using the thus-treated charge transporting polymer material has good initial characteristics and excellent durability. Example 2 1 part of the charge transporting polymer material obtained in Production Example 2 was dissolved in 40 parts of dichloromethane, and activated clay (manufactured by Kanto Chemical Co., Ltd.)
After adding 0.2 parts and stirring at 25 ° C. for 30 minutes, the mixture was filtered and separated, washed twice with water, and then a dichloromethane solution was dropped into a large amount of methanol to precipitate a polymer. A processed product was obtained. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 2 together with Comparative Examples. Comparative Example 3 A photoconductor was prepared and evaluated in the same manner as in Example 1 except that the charge transporting polymer material obtained in Production Example 2 was used as it was. Comparative Example 4 A silica gel-treated product was obtained in the same manner as in Example 2, except that silica gel (Wako Gel C-300 manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Comparative Example 5 An acidic alumina-treated product was obtained in the same manner as in Example 2 except that acidic alumina (Alumina 90 acid manufactured by Merck) was used instead of activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Comparative Example 6 A neutral alumina-treated product was obtained in the same manner as in Example 2 except that neutral alumina (Alumina 90 neutral manufactured by Merck) was used instead of activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Comparative Example 7 A basic alumina-treated product was obtained in the same manner as in Example 2 except that basic alumina (alumina 90 basic manufactured by Merck) was used instead of activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1.

[0035]

[Table 2]

As can be seen from the above results, even when another charge transporting polymer material treated with activated clay is used, the residual potential is smaller in both the initial evaluation and the evaluation after fatigue than in the case of no treatment. It can be seen that the method is effective as a method for purifying a polymer material for an electrophotographic photosensitive member. In addition, silica gel, acidic alumina, neutral alumina, and basic alumina, which are known as adsorbents other than activated clay, cannot achieve the same effect, indicating that the effect is specific to activated clay. Further, it can be seen that the electrophotographic photoreceptor using the thus-treated charge transporting polymer material has good initial characteristics and excellent durability. Example 3 5 parts of the polymer obtained in Production Example 3 was dissolved in 120 parts of toluene (dielectric constant: 2.24), 1 part of activated clay was added, and the mixture was stirred at 25 ° C. for 30 minutes. The toluene solution was dropped into methanol to precipitate a polymer, which was separated and dried to obtain a product treated with activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 3 shows the results together with Comparative Examples. Example 4 5 parts of the polymer obtained in Production Example 3 was dissolved in 120 parts of toluene, 1 part of activated clay was added, and the mixture was heated under reflux for 2 hours, separated by filtration, and the toluene solution was dropped into methanol. The polymer was precipitated, separated and dried to obtain a treated activated clay product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 3 shows the results together with Comparative Examples. Example 5 An activated clay-treated product was obtained in the same manner as in Example 4 except that the heating reflux time was changed to 30 minutes. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 3 shows the results together with Comparative Examples. Comparative Example 8 A photoconductor was prepared and evaluated in the same manner as in Example 1, except that the polymer obtained in Production Example 3 was used as it was. Comparative Example 9 5 parts of the polymer obtained in Production Example 3 was
0 parts, and dropped into acetone to precipitate a polymer. After the separation, this reprecipitation operation was repeated twice to obtain a reprecipitated product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Comparative Example 10 A photoconductor was prepared and evaluated in the same manner as in Example 3, except that the activated clay treatment of the polymer obtained in Production Example 3 was performed twice. Comparative Example 11 A photoconductor was prepared and evaluated in the same manner as in Example 3 except that the activated clay treatment of the polymer obtained in Production Example 3 was performed three times. Comparative Example 12 5 parts of the polymer obtained in Production Example 3 was dissolved in 120 parts of toluene, washed twice with 150 parts of a 2% hydrochloric acid aqueous solution, and then washed three times with water. Thereafter, the toluene layer was separated, and dropped into methanol to precipitate a polymer. The polymer was separated and dried to obtain an acid-washed product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1.

[0037]

[Table 3]

As can be seen from the above results, when the charge transporting polymer material treated with activated clay is used, the residual potential is smaller in both the initial evaluation and the evaluation after fatigue than in the case of no treatment. It can be seen that the method is effective as a method for purifying a polymer material for a photoreceptor. Further, the treatment at the reflux temperature of toluene (about 110 ° C.) further reduces the residual potential, indicating that there is a great purification effect. Further, it can be seen that the electrophotographic photoreceptor using the thus-treated charge transporting polymer material has good initial characteristics and excellent durability. Example 6 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of toluene, and the activated clay 1 was dried at 200 ° C. for 3 hours in advance.
After stirring at 25 ° C for 120 minutes, the mixture was filtered and separated, and a toluene solution was dropped into methanol to precipitate a polymer. The polymer was separated and dried to obtain a treated activated clay product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 4 shows the results together with Comparative Examples. Example 7 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of toluene, 1 part of activated clay was added, and the mixture was heated and refluxed for 5 hours, separated by filtration, and the toluene solution was added dropwise to methanol. The polymer was precipitated, separated and dried to obtain a treated activated clay product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 4 shows the results together with Comparative Examples. Example 8 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of toluene, 1 part of activated clay was added, and the mixture was heated under reflux for 15 minutes, separated by filtration, and the toluene solution was added dropwise to methanol. The polymer was precipitated, separated and dried to obtain a treated activated clay product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 4 shows the results together with Comparative Examples. Example 9 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of tetrahydrofuran (dielectric constant: 7.58), 1 part of activated clay was added, and the mixture was heated and refluxed for 15 minutes. Was dropped into methanol to precipitate a polymer, which was separated and dried to obtain a treated product of activated clay.
Using this product, a photoconductor was prepared in the same manner as in Example 1,
evaluated. Table 4 shows the results together with Comparative Examples. Example 10 5 parts of the polymer obtained in Production Example 4 was dissolved in 150 parts of 1,2-dichloroethane (dielectric constant: 10.45), 1 part of activated clay was added, and the mixture was heated under reflux for 15 minutes, and then separated by filtration. Then, a toluene solution was dropped into methanol to precipitate a polymer, which was separated and dried to obtain a treated product of activated clay. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Table 4 shows the results together with Comparative Examples. Comparative Example 13 A photoconductor was prepared and evaluated in the same manner as in Example 1, except that the polymer obtained in Production Example 4 was used as it was. Comparative Example 14 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of toluene, 2.5 parts of Molecular Sieves 5A was added, the mixture was stirred at room temperature for 3 hours, separated by filtration, and the toluene solution was dissolved in methanol. To precipitate a polymer, which was separated and dried to obtain a zeolite-treated product. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1. Comparative Example 15 5 parts of the polymer obtained in Production Example 4 was dissolved in 120 parts of toluene, 2.5 parts of activated carbon was added, the mixture was heated under reflux for 130 minutes, separated by filtration, and the toluene solution was added dropwise to methanol. Then, the polymer was precipitated, separated and dried to obtain a product treated with activated carbon. Using this product, a photoreceptor was prepared and evaluated in the same manner as in Example 1.

[0039]

[Table 4]

As can be seen from the above results, when the charge transporting polymer material treated with activated clay was used, the residual potential was smaller both in the initial evaluation and in the evaluation after fatigue as compared with the case of no treatment, and the electrophotographic photosensitive member was reduced. It is found that the method is effective as a method for purifying a polymer material for use. The reflux temperature of toluene (about 110 ° C.), the reflux temperature of tetrahydrofuran (about 66 ° C.), and the reflux temperature of 1,2-dichloroethane (about 8 ° C.)
3 ° C.), the residual potential is further reduced,
It can be seen that there is a great purification effect. However, as compared with the case where toluene or tetrahydrofuran having a dielectric constant smaller than 8 is used as a solvent, 1,2-
The effect is small when dichloroethane is used. Further, when the molecular weight of the treated product of Example 7 was measured, it was found that the number average molecular weight was 18,000 and the weight average molecular weight was 64200, which was smaller than the molecular weight before the treatment. When the molecular weight of the treated product of Example 8 was measured, the number average molecular weight was 35,500 and the weight average molecular weight was 89,300, indicating that there was no change from the molecular weight before the treatment. As described above, if the treatment time at the time of heating is too long, there is a risk that the molecular chains may be cut. However, it is shown that by performing the treatment within an appropriate time, purification can be performed without cutting. In addition, zeolite or activated carbon, which is known as an adsorbent other than activated clay, cannot achieve the same effect, indicating that the effect is specific to activated clay. Further, it can be seen that the electrophotographic photoreceptor using the thus-treated charge transporting polymer material has good initial characteristics and excellent durability. Example 11 5 parts of the polymer obtained in Production Example 5 was dissolved in 120 parts of toluene, 2.5 parts of activated clay was added, and the mixture was heated under reflux for 30 minutes, separated by filtration, and the toluene solution was dropped into methanol. Then, a polymer was precipitated, separated and dried to obtain a product treated with activated clay. 10 parts of this product and N- [4- (2,2
-Diphenylvinyl) phenyl] -N, N-diphenylamine was prepared in the same manner as in Photoreceptor Preparation Method 1, except that 9 parts of the same were dissolved in dichloromethane and used as a coating solution for the charge transport layer. This photoreceptor was evaluated in the same manner as in Example 1. The results are shown in Table 5 together with Comparative Examples. Comparative Example 16 A photoconductor was prepared and evaluated in the same manner as in Example 9, except that the polymer obtained in Production Example 5 was used as it was.

[0041]

[Table 5]

As described above, also in the case of the binder resin in the charge transport layer, the treatment with activated clay has an effective purification effect, and by using the polymer material for an electrophotographic photoreceptor thus treated, It can be seen that a photoreceptor having excellent charge stability, low residual potential, high sensitivity, and excellent durability thereof can be obtained.

[0043]

As described above, by treating a polymer material for an electrophotographic photosensitive member with activated clay, impurities serving as a source of residual potential can be effectively removed. Further, at that time, it is possible to purify more effectively by heating at 65 ° C. or more, and further effective by heating to 65 ° C. or more using a solvent having a dielectric constant of 8 or less. Purification becomes possible. These purification methods can be widely applied to polymer materials for electrophotographic photoreceptors, and are particularly suitably applied to purification of polymer materials contained in the charge transport layer and charge transport polymer materials. These processes make it possible to easily purify a polymer material which has been difficult to purify and which cannot be used until now to a purity which can be used as a material for electrophotography. In addition, by using such a material having a high purity, a highly durable electrophotographic photoreceptor having excellent chargeability, low generation of residual potential, high sensitivity, and little change in those characteristics is provided. You can do it.

 ──────────────────────────────────────────────────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-company (72) Inventor Katsuhiro Morooka 66-2 Horikawa-cho, Saisaki-ku, Kawasaki-shi, Kanagawa F-term (reference) 2H068 AA13 AA20 AA21 BB26 BB49 EA04 EA05

Claims (6)

[Claims] 1. A method for purifying a polymer material for an electrophotographic photosensitive member, comprising dissolving a polymer material for an electrophotographic photosensitive member in an organic solvent, and bringing the solution into contact with activated clay. 2. A method for purifying a polymer material for an electrophotographic photosensitive member, comprising: dissolving a polymer material for an electrophotographic photosensitive member in an organic solvent; and bringing the solution into contact with activated clay at 65 ° C. or higher. . 3. A high-density electrophotographic photosensitive member comprising: dissolving a polymer material for an electrophotographic photosensitive member in an organic solvent having a dielectric constant of 8 or less, and contacting the solution with activated clay at 65 ° C. or more. A method for purifying molecular materials. 4. The method according to claim 1, wherein the polymer material for the electrophotographic photosensitive member is a polymer material used for the charge transport layer.
4. The method for purifying a polymer material for an electrophotographic photosensitive member according to claim 2 or claim 3. 5. The electrophotographic photoreceptor according to claim 1, wherein the polymer material for the electrophotographic photoreceptor is a charge transporting polymer material used for a charge transport layer. Purification method for polymer materials. 6. An electrophotographic photoreceptor comprising a polymer material processed by any of the purification methods described in claim 1.