JPH09106084A - Polycarbonate resin for electrophotographic photoreceptor binder and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide polycarbonate resin for an electrophotographic photoreceptor binder involving a less electrification error by restraining the amount of nitrogen bonded to the molecular terminal of binder resin to a level equal to or below the specified value. SOLUTION: The amount of nitrogen bonded to the molecular terminal of polycarbonate resin is equal to or less than 10ppm. In this case, bivalent phenol used to manufacture the polycarbonate resin should preferably be selected from a group consisting of bivalent 2,2-bis(4-hydoxyphenyl) propane, 1,1-bis(4- hydoxyphenyl) cyclohexane, 2,2-bis(4-hydroxy-3-methyl phenyl) propane, 1,1-bis(4- hydroxy phenyl)-1-phenyl ethane. For the reduction of the amount oF the nitrogen bonded to the molecular terminal, the amount of tertiary amine to be used is minimized within a range not reducing a polymerization speed. In other words, 0.02 to 0.05mol% of the tertiary amine as a polymerization catalyst may be used for the bivalent phenol as the raw material of the polycarbonate.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polycarbonate resin for an electrophotographic photoreceptor binder.
More specifically, the present invention relates to a polycarbonate resin for an electrophotographic photoreceptor binder, which has a small amount of nitrogen bonded to the terminal of the molecule and has less abnormal charging.

[0002]

2. Description of the Related Art At present, electrophotographic technology is widely applied to copying machines and various printers because of its high speed and high image quality. Conventionally, inorganic electroconductive materials such as selenium, selenium / tellurium alloys, selenium / arsenic alloys, and cadmium sulfide have been mainly used as electrophotographic photoreceptors in this electrophotographic technique.

However, in recent years, electrophotographic photoreceptors using organic photoconductive substances have been developed in view of toxicity, safety, cost, productivity and the like. When the organic photoconductive substance is a low molecular weight substance, it is usually mixed with a binder resin to form a coating film. As binder resin, vinyl polymers such as polymethylmethacrylate, polystyrene, polyvinyl chloride, and their copolymers, polycarbonate, polyester, polysulfone, phenoxy resin, epoxy resin, silicone resin, and other various thermoplastic resins and thermosetting Resins have been used. Of these various resins, polycarbonate resins are often used because they have relatively excellent properties.

As one using a polycarbonate resin as a binder resin, for example, JP-A-59-71057.
The polycarbonate resin derived from bisphenol Z is disclosed in JP-A-63-170647, and the polycarbonate resin derived from bisphenol A is disclosed in JP-A-63-170647.
-148263 is a polycarbonate resin derived from dimethylbisphenol A, and is also disclosed in JP-A-4-440.
48 discloses that a polycarbonate resin derived from bisphenol AP is used as a binder resin.

These known organic photoconductive substances (OP
In the electrophotographic photosensitive member using C) and various binder resins, those comparable in electrosensitivity to those using an inorganic photoconductive substance have been obtained in terms of sensitivity and the like.
The image quality and durability were sometimes inferior. Impurities contained in the binder resin can be mentioned as factors that affect the image quality (Japanese Patent Application No. 5-229050, JP-A-60-973).
60). When these techniques are used, the effect on the image quality such as pinholes (small black dots) is reduced under normal use conditions.

However, recently, the conditions under which a copying machine, a fax machine or the like is used have become more severe, and the effect particularly under high temperature and high humidity environment is that even if the above-mentioned binder resin with reduced impurities is used, charging is not performed. There was a problem that minute black spots (pinholes) were generated due to abnormalities.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a resin for an electrophotographic photoreceptor binder which is suitable for an electrophotographic photoreceptor in which abnormal charging of the photoreceptor under high temperature and high humidity is suppressed.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on an electrophotographic photosensitive member having the above drawbacks improved, and as a result, generation of minute black spots under high temperature and high humidity and the amount of nitrogen bonded to the molecular end of the binder resin. Has been found to be related to abnormal charging, and has arrived at the present invention.

That is, the present invention relates to a polycarbonate resin for an electrophotographic photoreceptor binder, in which the amount of nitrogen bonded to the molecular end of the polycarbonate resin is 10 ppm or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polycarbonate resin itself of the present invention is obtained by an interfacial polymerization method (phosgene method) using a dihydric phenol and phosgene, which is a conventionally known method, or a transesterification reaction of a dihydric phenol and a diaryl carbonate. Obtainable. According to the transesterification method, it is possible to produce a polycarbonate resin containing substantially no nitrogen at the molecular end, but it is difficult to remove the inorganic catalyst and antioxidant used in the reaction that affects the electrophotographic properties. However, in reality, most of the binder resins for electrophotographic photoreceptors are rarely used, and in practice, most of the polycarbonate resins used for binders for electrophotographic photoreceptors are based on the interfacial polymerization method. Therefore, the polycarbonate resin in the present invention is mainly produced by the interfacial polymerization method.

In the interfacial polymerization method, dihydric phenols and phosgene are usually reacted in the presence of an acid binder and a solvent. Examples of the acid binder include pyridine and
Alkali metal hydroxides such as sodium hydroxide and potassium hydroxide are used, and as the solvent, for example, methylene chloride, chloroform, chlorobenzene, xylene and the like are used. Further, a catalyst such as a tertiary amine such as triethylamine or a quaternary ammonium salt is used to accelerate the polycondensation reaction. Further, in order to control the degree of polymerization, it is desirable to add a molecular weight regulator such as phenol, pt-butylphenol, or long-chain alkyl-substituted phenol to carry out the reaction. If desired, a small amount of an antioxidant such as sodium sulfite or hydrosulfite or a branching agent such as phloroglucin or isatin bisphenol may be added.

The reaction is usually 0 to 150 ° C., preferably 5 to
The temperature is suitably in the range of 40 ° C., and the reaction time depends on the reaction temperature, but is usually 0.5 minutes to 10 hours, preferably 1 minute to 2 hours. During the reaction, it is desirable to maintain the pH of the reaction system at 10 or more.

Specific examples of the dihydric phenol used for producing the polycarbonate resin of the present invention include biphenol, bis (4-hydroxyphenyl) methane, bis (4-hydroxyphenyl) ether and bis (4-hydroxyphenyl). Sulfone, bis (4-hydroxyphenyl) sulfoxide, bis (4-hydroxyphenyl)
Sulfide, bis (4-hydroxyphenyl) ketone, 1,1-bis (4-hydroxyphenyl) ethane,
2,2-bis (4-hydroxyphenyl) propane (bisphenol A; BPA), 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z; BPZ),
2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,
5-dichlorophenyl) propane, 2,2-bis (4-
Hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3-chlorophenyl) propane,
2,2-bis (4-hydroxy-3-methylphenyl)
Propane (Dimethylbisphenol A; DMBPA), 2,
2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane (bisphenol AP; BPA
P), bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 2,2-bis (4-hydroxy-3-)
Allylphenyl) propane, α, ω-bis [2- (p-hydroxyphenyl) ethyl] polydimethylsiloxane,
9,9-bis (4-hydroxyphenyl) fluorene,
2,2-bis (4-hydroxy-3-allylphenyl)
Propane, 4,4 '-[1,4-phenylenebis (1-
Methyl ethylidene)] bisphenol, 4,4'-
Examples include [1,3-phenylene bis (1-methylethylidene)] bisphenol. These may be used in combination of two or more.

Of these, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane and 2,2-bis (4-) are particularly preferable.
Hydroxy-3-methylphenyl) propane, 1,1-
It is preferably selected from bis (4-hydroxyphenyl) -1-phenylethane.

The tertiary amine of the polymerization catalyst used in the production of the polycarbonate of the present invention is triethylamine,
Tri-n-propylamine, tri-n-butylamine,
Although there are diethylaminopyridine and the like, triethylamine is preferable from the viewpoint of catalytic activity and washing removal. Examples of the polymerization promoter include quaternary ammonium salts such as tetramethylammonium chloride, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, tetraethylammonium bromide, and tetra-n-butylammonium iodide. Benzyltriethylammonium chloride is preferred because of its ease and reactivity.

The nitrogen bonded to the molecular end of the polycarbonate may be due to a urethane-bonded nitrogen compound (carbamate) formed by the reaction of a tertiary amine used as a polymerization catalyst during the production of the polycarbonate with the polymer end group. For example, JP-A-3-199231 and JP-A-3-19923
-133425, it is described that the urethane bond at the molecular end becomes a coloring factor in general molded products. As a method of reducing the urethane end, a fine control of the emulsified state or a tertiary Although it is described that the addition timing of the amine is greatly shifted, it is not practical because it is not easy to control.

As a method for reducing the nitrogen bonded to the molecular end in the present invention, a method for reducing the amount of the tertiary amine used as much as possible within the range where the polymerization rate is not lowered was examined. That is, in the present invention, the nitrogen bonded to the molecular end is
As a method of reducing the amount to pm or less, a tertiary amine as a polymerization catalyst is added to the starting dihydric phenol of polycarbonate in an amount of 0.
It becomes possible by using 02 to 0.05 mol%. Further, it is preferable to use a quaternary ammonium salt as a reaction co-catalyst in an amount of 0.4 to 1.0 mol% with respect to the raw material dihydric phenol in order to improve the reaction rate. When the tertiary amine of the polymerization catalyst is less than 0.02 mol%, the polymerization reaction is remarkably slowed, the contact time with alkali increases, and unreacted dihydric phenol increases. If it exceeds 0.05 mol%, the polymerization reaction will proceed sufficiently, but the amount of nitrogen bonded to the terminal of the molecule exceeds 10 ppm, which is not preferable.

In the present invention, the nitrogen bonded to the molecular end of the polycarbonate resin has a high temperature and high humidity environment (60 ° C., 9 ° C.).
It was confirmed that when the concentration exceeds 0 ppm at 0% RH), the number of minute black spots increases sharply, and when the amount is 10 ppm or less, particularly 6 ppm or less, the generation of minute black spots almost disappears.

The electrophotographic photosensitive member in which the polycarbonate resin of the present invention is used as a binder resin may be either one having a single photoconductive layer on a conductive support or one having a function-separated laminate type. Recently, a laminated electrophotographic photoreceptor having two layers of a charge generation layer that generates a charge upon exposure and a charge transport layer that transports the charge has become mainstream. Further, if necessary, an undercoat layer, a protective layer, an adhesive layer, etc. may be provided.

The conductive support is made of a metal material such as aluminum, stainless steel or nickel, or a polyester film having a conductive layer such as aluminum, palladium, tin oxide or indium oxide on its surface, a phenol resin,
Paper or the like is used.

The charge generating layer is formed on the conductive support by a known method. Examples of the charge generating substance include azoxybenzene-based, disazo-based, trisazo-based,
Organic pigments such as benzimidazole-based, polycyclic quinoline-based, indigoid-based, quinacridone-based, phthalocyanine-based, perylene-based, and methine-based pigments can be used.

Fine particles of these charge generating substances are polyvinyl butyral resin, polyvinyl formal resin,
Silicone resin, polyamide resin, polyester resin,
Polystyrene resin, polycarbonate resin, polyvinyl acetate resin, polyurethane resin, phenoxy resin,
It is used in the form of being dispersed in a binder resin such as an epoxy resin or various types of cellulose.

The charge transport layer is formed on the charge generation layer by a known method by dispersing the charge transport substance (CT agent) using the copolycarbonate polymer of the present invention as a binder resin.

Examples of the CT agent include polytetracyanoethylene; fluorenone compounds such as 2,4,7-trinitro-9-fluorenone; nitro compounds such as dinitroanthracene; succinic anhydride; maleic anhydride; dibromomaleic anhydride. Acid; triphenylmethane compound;
2,5-di (4-dimethylaminophenyl) -1,3
Oxadiazole compounds such as 4-oxadiazole;
Styryl compounds such as 9- (4-diethylaminostyryl) anthracene; carbazole compounds such as poly-N-vinylcarbazole; pyrazoline compounds such as 1-phenyl-3- (p-dimethylaminophenyl) pyrazoline; 4,4 Amine derivatives such as', 4 "-tris (N, N-diphenylamino) triphenylamine; conjugated unsaturated compounds such as 1,1-bis (4-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene 4-
(N, N-diethylamino) benzaldehyde-N, N
-Hydrazone compounds such as diphenylhydrazone; indole compounds, oxazole compounds, isoxazole compounds, thiazole compounds, thiadiazole compounds, imidazole compounds, pyrazole compounds,
Nitrogen-containing cyclic compounds such as pyrazoline compounds and triazole compounds; condensed polycyclic compounds and the like. The above C
The T agent may be used alone or in combination of two or more kinds.

The charge generating layer and the charge transporting layer are prepared by dissolving the above charge generating substance or the charge transporting substance in a binder resin and an appropriate solvent, and dipping the solution in a solution by dipping, spraying, It can be formed by applying by a roll coating method, a bar coating method or the like and drying. This solvent can be roughly classified into two types, a halogen-based organic solvent and a non-halogen-based solvent. Generally, halogen-based solvents that are less flammable are often used, but in recent years, from the viewpoint of safety and environmental protection. The proportion of non-halogenated solvents used is increasing.

As the non-halogen solvent, aromatic solvents such as benzene, toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, ether solvents such as tetrahydrofuran, dioxane and ethylene glycol diethyl ether, methyl acetate and ethyl acetate. , Ester solvents such as ethyl cellosolve, alcohol solvents such as methanol, ethanol and isopropanol, and dimethylformamide, dimethylsulfoxide, diethylformamide and the like. Further, examples of the halogen-based solvent include methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, tetrachloroethane, chlorobenzene, and the like. These solvents may be used alone, regardless of whether they are halogen-free or halogen, or two kinds. The above may be used in combination and used as a solvent for mixing. The concentration of the solution is usually 1 to 30% by weight, preferably 5 to 20% by weight.

When the polycarbonate resin of the present invention is used as a binder resin, the mixing ratio of the charge generating substance and the binder resin is preferably in the range of 10: 1 to 1:20. The thickness of the charge generation layer is 0.01 to 20 μm, preferably 0.1 to 2 μm.

The mixing ratio of the charge transport material and the binder resin is preferably in the range of 10: 1 to 1:10. The thickness of this charge transport layer is 2 to 100 μm, preferably 5 to
30 μm is preferable.

When the polycarbonate resin of the present invention is used as a photoreceptor binder, various known additives conventionally used in polycarbonate resins can be blended, if desired, as stabilizers. , UV absorbers, lubricants, dyes, pigments, flame retardants and the like.

When the polycarbonate resin of the present invention is used as a binder resin for a charge transport material, compared with a conventional polycarbonate resin as a binder resin,
It has an advantage of suppressing abnormal charging in a high temperature and high humidity environment and suppressing generation of minute black spots that deteriorate image quality.

[0031]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

Example 1 3.7 kg of sodium hydroxide was dissolved in 42 l of water,
1,1-bis (4-hydroxyphenyl) cyclohexane (hereinafter referred to as "BPZ") 8.5k while maintaining at ℃
g and 8 g of hydrosulfite were dissolved. 28 g of methylene chloride was added to this and 130 g of p-t-butylphenol (hereinafter referred to as "PTBP") was added with stirring, and then 4.0 kg of phosgene was blown in for 60 minutes. After the completion of blowing phosgene, the reaction solution was emulsified by vigorously stirring, and after emulsification, 1.5 g of triethylamine was added and stirring was continued for about 1 hour for polymerization. After the reaction, the polymerization liquid was separated into an aqueous phase and an organic phase, the organic phase was neutralized with phosphoric acid, and then repeatedly washed with water until the pH of the washing liquid became neutral, and then 35 liters of isopropanol was added to carry out polymerization. The material was allowed to settle.
The precipitate was filtered and then dried to obtain a powdery polycarbonate resin having an intrinsic viscosity of 0.49 dl / g (20 ° C., methylene chloride solution) (hereinafter referred to as “P-
1 ”). When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 9 ppm.

Example 2 The procedure of Example 1 was repeated, except that 72 g of benzyltriethylammonium chloride was added after the blowing of phosgene and the amount of triethylamine was changed to 0.7 g after emulsification. Obtained powdery polycarbonate resin (hereinafter "P-2")
Had an intrinsic viscosity of 0.48. When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 6 ppm.
Met.

Example 3 Instead of BPZ, 2,2-bis (4-hydroxy-3)
-Methylphenyl) propane (hereinafter referred to as "BPC")
Example 1 was repeated except that 8.1 kg and PTBP of 150 g were used. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter referred to as "P-3") is 0.6.
It was 0. When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 10 ppm.

Example 4 1,1-bis (4-hydroxyphenyl) -1-phenylethane (hereinafter referred to as "BPAP") instead of BPZ
The same procedure as in Example 2 was performed except that 9.2 Kg and 300 g of PTBP were used. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter referred to as "P-4") is 0.
It was 37. The total amount of nitrogen contained in this polycarbonate resin was measured and found to be 5 ppm.

Comparative Example 1 Example 1 was repeated except that the amount of triethylamine was changed to 2.0 g. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter “P-5”) was 0.49. When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 12 ppm.

Comparative Example 2 The procedure of Example 1 was repeated except that the amount of triethylamine was 4.0 g. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter “P-6”) was 0.49. When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 23 ppm.

Comparative Example 3 The procedure of Example 1 was repeated except that the amount of triethylamine was 8.0 g. The intrinsic viscosity of the obtained powdery polycarbonate resin (hereinafter “P-7”) was 0.49. When the total amount of nitrogen contained in this polycarbonate resin was measured, it was 57 ppm.

Test Example τ-type copper phthalocyanine 10 was formed on a polyethylene terephthalate film on which aluminum was vapor-deposited to a thickness of about 50 nm.
Parts and phenoxy resin 5 parts, polyvinyl butyral resin 5
And 100 parts of dimethoxyethane were mixed and pulverized and dispersed by a sand grind mill to apply a coating solution, which was then dried to form a charge generation layer having a thickness of about 0.5 μm. next,
4- (N, N-diethylamino) benzaldehyde-
50 parts of N, N-diphenylhydrazone, Examples 1-4
The polycarbonate resin (P-1, P-
2, P-3, P-4) each and 50 parts of chloroform and 350 parts of chloroform to prepare a coating solution, which is applied on the charge generation layer, air-dried and then dried at 100 ° C. for 8 hours to have a thickness of about 20
A charge transport layer having a thickness of μm was provided to prepare a laminated electrophotographic photosensitive member. The prepared electrophotographic photoreceptor is 60 ° C, 90% RH
Was left under the environment for 100 hours.

The electrophotographic photosensitive member was evaluated 30 times by using a commercially available copying machine having a blade cleaning system and a scorotron charger, and a small black dot (diameter 100 to 500 μm) was obtained. The average number of A4 copy sheets (above) was visually determined.

Table 1 shows the nitrogen content and the average number of minute black dots of the polycarbonates of Examples 1 to 4 and Comparative Examples 1 to 3. (Below margin)

[0042]

[Table 1]

[0043]

INDUSTRIAL APPLICABILITY The polycarbonate resin of the present invention has a small amount of nitrogen bonded to its molecular end, and when used as a binder resin for an electrophotographic photoreceptor of a copying machine or the like, there is almost no charging abnormality even in a high temperature and high humidity environment, and it is clear. An image is obtained.
Therefore, the range of usage conditions of the copying machine is widened, and the life and maintenance cycle of the photoconductor can be extended.

Claims (5)

[Claims] 1. A polycarbonate resin for a binder of an electrophotographic photosensitive member, characterized in that the amount of nitrogen bonded to the molecular end of the polycarbonate resin is 10 ppm or less. 2. A polycarbonate resin is 2,2-bis (4
-Hydroxyphenyl) propane, 1,1-bis (4-
Hydroxyphenyl) cyclohexane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane,
The polycarbonate resin for an electrophotographic photoreceptor binder according to claim 1, which is derived from a dihydric phenol selected from the group consisting of 1,1-bis (4-hydroxyphenyl) -1-phenylethane. 3. The polycarbonate resin as a binder for an electrophotographic photoreceptor according to claim 1, wherein the amount of nitrogen bonded to the molecular end is 6 ppm or less. 4. Nitrogen bonded to a molecular end, characterized in that a tertiary amine polymerization catalyst used in the production of a polycarbonate resin by an interfacial polymerization method is used in an amount of 0.02 to 0.05 mol% based on the starting dihydric phenol. Is 10 ppm or less, a method for producing a polycarbonate resin for an electrophotographic photoreceptor binder. 5. The method for producing a polycarbonate resin for an electrophotographic photoreceptor binder according to claim 4, wherein a quaternary ammonium salt is used as a cocatalyst in an amount of 0.4 to 1.0 mol% based on the starting dihydric phenol. .