JPH08278641A - Electrophotographic photoreceptor - Google Patents

Abstract

PURPOSE: To provide an electrophotographic photoreceptor excellent in durability with polycarbonate resin excellent in heat and wear resistances as well as optical characteristics and having high surface hardness. CONSTITUTION: In an electrophotographic photoreceptor obtd. by forming a photosensitive layer on an electrically conductive substrate, polycarbonate resin obtd. by allowing dihydric phenol, substatially dihydric phenol represented by the formula [where each of R1 and R2 is 1-6C hydrocarbon or halogen and each of (m) and (n) is an independent integer of 0-4, respectively] to react with a precursor of polycarbonate is incorporated into the photosensitive layer. The specific viscosity of a soln. prepd. by dissolving 0.7g of the polycarbonate resin in 100ml methylene chloride is 0.160-1.882 at 20 deg.C.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrophotographic photoreceptor using a polycarbonate resin. More specifically, it relates to an electrophotographic photoreceptor having excellent durability, which uses a polycarbonate resin having excellent heat resistance and abrasion resistance and having a high surface hardness as a binder resin for a photosensitive layer.

[0002]

2. Description of the Related Art Conventionally, a typical polycarbonate resin has been obtained by reacting 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A) with a carbonate precursor such as phosgene or diphenyl carbonate. It is known that the polycarbonate resin is excellent in transparency, heat resistance, dimensional accuracy, etc., and is used in many fields. However, in recent years, in consideration of lightness, thinness, shortness, and increased use under more severe conditions, higher heat resistance is required in addition to optical characteristics such as light transmittance. In order to provide a polycarbonate resin having heat resistance superior to that of bisphenol A, various polycarbonate resins using a dihydric phenol that is more rigid than bisphenol A have been proposed, but what is still satisfactory is Absent. Further, the polycarbonate resin from bisphenol A is inferior in abrasion resistance and surface hardness, and if it is used as a binder resin for the photosensitive layer in the electrophotographic photoreceptor, the durability of the electrophotographic photoreceptor becomes insufficient. Development of a polycarbonate resin having excellent heat resistance and abrasion resistance in addition to optical properties and high surface hardness is desired.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides an electrophotographic photosensitive member excellent not only in optical characteristics but also in heat resistance and abrasion resistance, and using a polycarbonate resin having a high surface hardness. With the goal.

The present inventor has conducted extensive studies to achieve the above object, and as a result, a polycarbonate resin obtained by reacting a dihydric phenol having a specific structure with a carbonate precursor has not only transparency but also heat resistance. It was also found that the electrophotographic photoreceptor having excellent abrasion resistance and high surface hardness and using this resin as a binder resin for the photosensitive layer has significantly improved durability. The present invention has been completed based on this finding.

[0005]

The present invention provides a photosensitive layer in an electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer formed on the conductive substrate.

[0006]

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[Wherein R 1 and R 2 are each independently a hydrocarbon group having 1 to 6 carbon atoms or a halogen atom;
And n are each independently an integer of 0 to 4. ] A solution obtained by reacting a carbonate precursor with a dihydric phenol mainly containing dihydric phenol and dissolving 0.7 g of the dihydric phenol in 100 ml of methylene chloride has a specific viscosity at 20 ° C of 0.160 to 1 The present invention relates to an electrophotographic photosensitive member containing a polycarbonate resin of 0.882.

The dihydric phenol, which is a raw material of the polycarbonate resin used in the present invention, is a dihydric phenol represented by the above general formula [1]. Examples of such dihydric phenol include 1,1-bis (4-hydroxy). Phenyl) -4
-Isopropylcyclohexane, 1,1-bis (3-methyl-4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (3-ethyl-4-hydroxyphenyl) -4-isopropylcyclohexane,
1,1-bis (3-propyl-4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (3- Allyl-
4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (3-bromo-4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-
Examples thereof include bis (3-chloro-4-hydroxyphenyl) -4-isopropylcyclohexane and 1,1-bis (3-fluoro-4-hydroxyphenyl) -4-isopropylcyclohexane. Among them, 1,1-bis ( 4-
Hydroxyphenyl) -4-isopropylcyclohexane is preferred.

Further, a part of the dihydric phenol represented by the above general formula [1] may be replaced with another dihydric phenol within a range not exceeding the gist of the present invention (usually 50 mol% or less). You can Examples of the other dihydric phenol used here include 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, and 1,1-bis (4
-Hydroxyphenyl) -1-phenylethane, bisphenol A, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane (hereinafter referred to as bisphenol Z), 2 , 2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl-
4-hydroxyphenyl) propane, 2,2-bis (4
-Hydroxyphenyl) butane, 2,2-bis (3,5
-Dimethyl-4-hydroxyphenyl) propane, 2,
2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxydiphenyl sulfide,
Examples thereof include 3,3′-dimethyl-4,4′-dihydroxydiphenyl sulfide and 4,4′-dihydroxydiphenyl oxide, with bisphenol A and bisphenol Z being preferred. Also, a small amount of a trifunctional compound can be used as a branching agent, and a part of the dihydric phenol can be replaced with a dicarboxylic acid.

To synthesize a polycarbonate resin from a dihydric phenol mainly containing the dihydric phenol represented by the general formula [1], a reaction between the dihydric phenol and the carbonate precursor is carried out. Examples of the carbonate precursor used here include phosgene, diphenyl carbonate,
Bischloroformates of the above dihydric phenols, di-p
-Tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like are mentioned, and among them, phosgene and diphenyl carbonate are preferable.

The reaction between the above dihydric phenol and the carbonate precursor is a reaction used when synthesizing a polycarbonate resin from a usual bisphenol A, for example, a reaction between a dihydric phenol and phosgene, or a reaction between a dihydric phenol and a bisaryl carbonate. A transesterification reaction is preferably used. In the reaction of dihydric phenol and phosgene,
The reaction is usually performed in the presence of an acid binder and a solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, pyridine or the like is used. As the solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. A catalyst such as a tertiary amine or a quaternary ammonium salt can be used to accelerate the reaction, and a terminal terminator such as phenol or p-tert-butylphenol is preferably used as a molecular weight regulator. The reaction temperature is usually 0 to 40 ° C., the reaction time is several minutes to 5 hours, and the pH during the reaction is usually preferably kept at 10 or higher.

In the transesterification reaction, the dihydric phenol and bisaryl carbonate are mixed in the presence of an inert gas, and the reaction is usually carried out at 120 to 350 ° C. under reduced pressure. The degree of reduced pressure is changed stepwise, and finally, the phenols produced at 1 mmHg or less are distilled out of the system. The reaction time is usually about 1 to 4 hours. Moreover, you may add a molecular weight regulator and antioxidant as needed.

The molecular weight of the polycarbonate resin must be such that 0.7 g of the polymer is dissolved in 100 ml of methylene chloride and the specific viscosity measured at 20 ° C. is 0.160 to 1.882. If the specific viscosity does not reach 0.160, it is difficult to obtain the intended photosensitive layer, and the specific viscosity is 1.882.
If it exceeds, the smoothness of the surface of the obtained photosensitive layer is deteriorated, and it becomes difficult to obtain sufficient durability. Particularly, the specific viscosity is 0.
A polycarbonate resin of 315 to 0.951 is preferable. In addition, various additives such as a heat stabilizer, an antioxidant, a light stabilizer, a colorant, an antistatic agent, a lubricant, and a release agent can be added to the polycarbonate resin, if necessary.

The electrophotographic photosensitive member of the present invention is used in copying machines and printers, and is characterized by comprising a conductive substrate and a photosensitive layer formed thereon, and containing the above polycarbonate resin in the photosensitive layer. And The present invention relates to a negative charging type in which a charge generating layer and a charge transporting layer are sequentially laminated on a conductive substrate, a negative charging type in which a protective layer is formed on the laminated negative charging type charge transporting layer, and a charge transporting layer is formed on a conductive substrate. Of positive charge type in which layers and charge generating layers are sequentially laminated, or single layer positive charge type in which a photosensitive layer having a single layer structure in which a charge transport substance and a charge generating substance are dispersed in a binder resin is formed on a conductive substrate. Can also be applied. Specifically, in the case of the laminated negative charging type, the above-mentioned polycarbonate resin is contained in the charge transport layer or the protective layer, and in the case of the laminated positive charging type, the above-mentioned polycarbonate resin is contained in the charge generation layer, and the photosensitive layer having a single-layer structure is formed. In the case of a layer, the above-mentioned polycarbonate resin is contained in the binder resin.

More specifically, in the case of the laminated negative charging type, the charge generating layer is obtained by pulverizing and dispersing the charge generating substance in a solvent, preferably having an average particle size of 0.3 μm or less, and a binder resin such as polyvinyl resin. Butyral, polyvinyl acetal, cellulose derivative, phenolic resin,
A film thickness of 0.05 on the conductive substrate by blending epoxy resin, etc.
The film is formed to about 5 μm. Further, instead of blending the binder resin with the dispersion liquid, a binder resin layer may be provided between the conductive substrate and the charge generation layer. Then, a charge transport layer composed of the above-mentioned polycarbonate resin and a charge transport material having a film thickness of about 15 to 50 μm is formed on the charge generation layer in the same manner as the charge generation layer. At this time, a ratio of 0.5 to 5 parts by weight of the charge transport material is preferable with respect to 10 parts by weight of the polycarbonate resin. Further, as the film forming method, for example, an arbitrary method such as a dipping method, a spray method, a roll method or the like is adopted.
When forming the protective layer, the thickness of the protective layer resin is 0.5.
The polycarbonate resin layer having a thickness of about 10 μm may be provided.

In the case of the laminated positive charging type, since the charge generation layer is on the surface layer, the above polycarbonate resin is contained in the charge generation layer. The charge generating substance is pulverized and dispersed in a solvent and then the above polycarbonate resin is blended, or the charge generating substance and the polycarbonate resin are pulverized and dispersed in a solvent, and a film thickness of 0 to 50 μm is formed on the charge transport layer. .5-1
A charge generation layer of about 0 μm is formed. At this time, the charge generating substance 2 to 3 is added to 10 parts by weight of the polycarbonate resin.
A ratio of 0 parts by weight is preferable. A binder resin such as polymethylmethacrylate, methylmethacrylate / styrene copolymer, polystyrene, polyester, polycarbonate resin, polyurethane or the like is used in the charge transport layer together with the charge transport material, and the above polycarbonate resin of the present invention may be used. . In the case of the single-layer positive charging type, it is preferable to use the charge transporting material in an amount of 0.5 to 5 parts by weight based on 10 parts by weight of the polycarbonate resin.

As the conductive substrate, for example, aluminum,
Aluminum, nickel, chromium, titanium, palladium, indium oxide, tin oxide, on a metal plate or metal sheet of brass, copper, nickel, steel, or a plastic sheet
Conductive materials such as graphite are deposited, sputtered,
It is possible to use a material which is coated by coating or the like and is made conductive. Examples of the charge generation material include various selenium-based alloy materials such as amorphous selenium, selenium / tellurium alloys, selenium / arsenic alloys, zinc oxide,
Inorganic photoconductors such as titanium oxide, phthalocyanine-based, squarerium-based, anthantrone-based, perylene-based, azo-based, anthracene-based, pyrene-based organic pigments and dyes such as pyrylium salts and thiapyrylium salts are used. Examples of the charge transport material include a heterocyclic compound such as carbazole, indole, imidazole, thiazole, pyrazole, and pyrazoline, an aniline derivative, a hydrazine derivative, a stilbene derivative, or an electron-donating material such as a polymer having a basic side chain formed of these compounds. Are used, and hydrazine derivatives, aniline derivatives and stilbene derivatives are particularly preferable.

[0018]

The present invention will be further described with reference to the following examples. The parts and% in the examples are parts by weight and% by weight, and the evaluation was performed by the following method. (1) Specific viscosity: 0.7 g / 1 using methylene chloride as a solvent
The concentration was set to 00 ml and the measurement was carried out at 20 ° C. (2) Glass transition temperature: measured by DuPont DSC910. (3) Total light transmittance: 0.2 obtained from methylene chloride solution
The total light transmittance of the mm-thick casting film was measured. (4) Evaluation of electrophotographic photosensitive member: The obtained electrophotographic photosensitive member was mounted on a copying machine having a blade cleaning member and after copying 50,000 sheets, the surface abrasion amount (μm) of the electrophotographic photosensitive member and the abrasion and scratches. The presence or absence of image defects due to (the image disturbance, black streaks and the like were visually determined) was examined. (5) Surface hardness: Measured by a pencil scratch test according to JIS K-5400.

Example 1 (A) In a reactor equipped with a thermometer, a stirrer and a dropping funnel, 344 parts of ion-exchanged water and a 48% aqueous sodium hydroxide solution 7
2.1 parts were charged, and 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane 60.
5 parts and 0.12 parts of hydrosulfite are dissolved, 162 parts of methylene chloride is added, and the mixture is stirred at 15 to 20 ° C.
Then, 25.1 parts of phosgene was blown in in 45 minutes. Next, 0.73 part of p-tert-butylphenol was added and emulsified, and then 0.07 part of triethylamine was added to 28 to 3
The reaction was completed by stirring at 3 ° C. for about 1 hour. After the completion of the reaction, the product was diluted with methylene chloride, washed with water, acidified with hydrochloric acid and washed with water. 0.6 part was obtained (yield 97%). This polymer has a specific viscosity of 0.366 and a glass transition temperature of 180.
C., the total light transmittance was 91%. (B) The following formula

[0020]

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100 parts of dimethoxyethane was added to 10 parts of the bisazo compound represented by and 10 parts of polyvinyl butyral resin, and pulverized and dispersed by a sand grind mill.
A mirror-finished aluminum cylinder having a diameter of 30 mm was immersed in the obtained dispersion liquid to obtain a charge generation layer of 0.15 μm. Then the following formula

[0022]

[Chemical 4]

10 parts of the hydrazone compound represented by and 10 parts of the polycarbonate resin obtained in (A) above as a binder resin are dissolved in 55 parts of methylene chloride, and this solution is applied onto the charge generation layer by a dipping method and dried. Then 20
An electrophotographic photoreceptor was obtained by forming a charge transport layer having a thickness of μm. Table 1 shows the evaluation results.

Example 2 In place of 60.5 parts of 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane of Example 1 (A), 1,1-bis (4-hydroxyphenyl)- 4-isopropylcyclohexane 5
Polycarbonate resin 6 in the same manner as in Example 1 (A) except that 4.4 parts and bisphenol A 4.4 parts were used.
2.6 parts (yield 98%) were obtained. The specific viscosity of this polymer was 0.432, the glass transition temperature was 177 ° C., and the total light transmittance was 91%. Example 1 using this polymer
An electrophotographic photosensitive member was produced in the same manner as in (B), and the evaluation results are shown in Table 1.

Example 3 1,1-bis (4-hydroxyphenyl) -in place of 60.5 parts of 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane of Example 1 (A) 4-isopropylcyclohexane 4
8.4 parts and 1,1-bis (4-hydroxyphenyl)
Example 1 except using 10.5 parts of cyclohexane
63.4 parts (yield 99%) of a polycarbonate resin was obtained in the same manner as in (A). The specific viscosity of this polymer is 0.4
52, glass transition temperature 178 ° C., total light transmittance 91
%Met. An electrophotographic photosensitive member was produced in the same manner as in Example 1 (B) using this polymer, and the evaluation results are shown in Table 1.

[Comparative Example 1] The glass transition temperature of a polycarbonate resin having a specific viscosity of 0.561 obtained from bisphenol A and phosgene by a conventional method was 150 ° C. An electrophotographic photosensitive member was produced in the same manner as in Example 1 (B) using this polymer, and the evaluation results are shown in Table 1.

[0027]

[Table 1]

[0028]

The polycarbonate resin used in the present invention is excellent in heat resistance and abrasion resistance and has a high surface hardness.
By including this polymer in the photosensitive layer, it becomes possible to provide an electrophotographic photosensitive member having excellent durability, and the effect produced by the electrophotographic photosensitive member is remarkable.

Claims (1)

[Claims] 1. A photosensitive layer in an electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer provided on the photosensitive layer, represented by the following general formula [1]: [In the formula, R 1 and R 2 are each independently C 1-6.
Is a hydrocarbon group or a halogen atom, and m and n are each independently an integer of 0 to 4. ] A dihydric phenol mainly consisting of dihydric phenol represented by the following formula is obtained by reacting a carbonate precursor with 0.7 g of methylene chloride.
The specific viscosity of the solution dissolved in 00 ml at 20 ° C is 0.1.
An electrophotographic photoreceptor containing a polycarbonate resin of 60 to 1.882.