JPH0682222B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an electrophotographic photoreceptor having high sensitivity and excellent durability, and from the viewpoint of application, electrophotographic copying machines, laser beam printers, CRT printers, electronic The present invention relates to an electrophotographic photoconductor that can be widely used in electrophotographic application fields such as a photoengraving system.

[Prior Art] In the field of photoconductive materials for electrophotographic photoconductors, various kinds of organic photoconductive materials have been developed in recent years, and in particular, a function-separated photoconductor in which a charge generation layer and a charge transport layer are laminated has already been put into practical use. Installed in machines and printers.

However, one of the major drawbacks has been that these photoreceptors generally have low durability.

Durability, sensitivity, residual potential, durability in electrophotographic physical properties such as charging ability and abrasion of the photoreceptor surface due to rubbing,
The mechanical durability such as scratches is roughly classified into two types, but in the current technical level, the main factor that determines the life of the photoconductor is often the latter mechanical durability.

Further, the surface layer of the photoconductor has a factor that causes deterioration of image quality such as adhesion of a low resistance substance due to ozone generated at the time of corona charging under high humidity, or filming or fusion due to poor cleaning of toner. Therefore, in addition to the above mechanical durability, releasability for various kinds of deposits is also required.

As a method for satisfying the properties required for the surface layer of the photoreceptor as described above, a means of dispersing powder of lubricating oil such as a fluororesin in the surface layer is known.

As a result, lubricity is given to the surface layer, mechanical durability against abrasion and scratches is improved, and releasability and water repellency are also given, so surface deterioration under high humidity and toner fusion prevention are prevented. Is also effective against.

However, the fluororesin powder has problems in dispersibility and cohesiveness, and it is difficult to form a uniform and smooth film. Therefore, the obtained surface layer has image defects such as image unevenness and pinholes. It was unavoidable to have.

In most cases, a binder resin or a dispersion aid having good dispersibility causes deterioration of electrophotographic characteristics, and no effective one is found at present.

[Problems to be Solved by the Invention] The present invention provides an electrophotographic photosensitive member which meets the above-mentioned requirements.

That is, an object of the present invention is to provide an electrophotographic photosensitive member having mechanical durability against abrasion and scratches on the surface due to rubbing.

Another object of the present invention is to provide an electrophotographic photosensitive member capable of obtaining a stable and high-quality image even under high humidity.

Another object of the present invention is to provide an electrophotographic photosensitive member which has good cleaning properties and does not adhere toner to the surface layer.

Further, another object of the present invention is to provide an electrophotographic photosensitive member which is free from uneven coating film and pinholes on the surface, does not accumulate residual potential in repeated electrophotographic processes, and can always obtain high-quality images. is there.

[Means and Actions for Solving Problems] The inventors of the present invention have earnestly studied in accordance with the above object, and as a result,
By dispersing the fluorine-based resin powder in the surface layer, by using a fluorine atom-containing polycarbonate as the dispersion binder,
The present invention has been achieved by finding that an electrophotographic photosensitive member that meets the above-mentioned requirements can be obtained.

That is, the present invention relates to an electrophotographic photosensitive member having a photosensitive layer on a conductive substrate, at least one layer of a fluorine atom-containing polycarbonate and one type of a fluorine-based resin powder in a layer farthest from the conductive substrate. Or more is contained.

More specifically, the fluororesin powder used in the present invention means tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylenepropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoride. It refers to ethylene chloride resin and powders of copolymerization thereof, and one or more powders are selected from these when used. The molecular weight of the resin, the particle size of the powder, and the like can be appropriately selected according to the specifications of the surface layer to be applied.

Next, the fluorine atom-containing polycarbonate used in the present invention contains a repeating unit represented by the following general formula [I] as a constituent component.

However, at least one of R ₁ , R ₂ , X ₁ , X ₂ , X ₃ , and X ₄ represents a fluorine atom and / or a substituent containing at least one fluorine atom. Examples of the substituent containing a fluorine atom include an alkyl group, an aryl group, an alicyclic alkyl group, an alkoxy group and the like, and R ₁ and R ₂ may form a cyclic structure with the carbon atom to which they are bonded. Further, a halogen atom, a lower alkyl group, an aryl group or the like may be further substituted.

Other than a fluorine atom and a substituent containing a fluorine atom
R ₁ and R ₂ are a hydrogen atom, an alkyl group, an aryl group, etc., and R ₁ and R ₂ may form a cyclic structure together with the carbon atom to which they are bonded. Further, a halogen atom, a lower alkyl group, an aryl group or the like may be substituted.

Other than a fluorine atom and a substituent containing a fluorine atom
X ₁ , X ₂ , X ₃ and X ₄ are a hydrogen atom, a halogen atom other than fluorine, an alkyl group, an alicyclic alkyl group, an aryl group, an alkoxy group and the like, which may further have a substituent.
n represents the degree of polymerization.

Further, the fluorine atom-containing polycarbonate used in the present invention is represented by the general formula [I] in which R ₁ , R ₂ , X ₁ , X ₂ , X ₃ , X ₄
It may be a copolymer with a polycarbonate containing no fluorine atom. In this case, the fluorine atom-containing portion in the fluorine atom-containing polycarbonate is preferably 5% by weight or more, more preferably 20% by weight or more.

The fluorine atom-containing polycarbonate used in the present invention can be produced by a general polycarbonate synthesis method such as the phosgene method using one or more diol compounds represented by the following general formula [II].

However, at least one of R ₃ , R ₄ , X ₅ , X ₆ , X ₇ , and X ₈ represents a fluorine atom and / or a substituent containing at least one fluorine atom. Examples of the substituent containing a fluorine atom include an alkyl group, an aryl group, an alicyclic alkyl group and an alkoxy group, and R ₃ and R ₄ may form a cyclic structure together with the carbon atom bonded thereto. Further, a halogen atom, a lower alkyl group, an aryl group or the like may be further substituted.

Other than a fluorine atom and a substituent containing a fluorine atom
X ₅ , X ₆ , X ₇ and X ₈ are a hydrogen atom, a halogen atom other than fluorine, an alkyl group, an alicyclic alkyl group, an aryl group, an alkoxy group and the like, which may further have a substituent.

Typical specific examples of the diol compound used in the present invention are shown below by structural formulas.

When such a fluorine atom-containing polycarbonate is used as a binder, the dispersibility of the fluororesin powder is much improved as compared with the case of using a general binder resin, and a uniform and smooth coating film is obtained. Is obtained. It is considered that this is because the fluorine atom contained as a constituent component of the polycarbonate has an affinity with the fluorine-based resin powder, and thus plays a role of a dispersion aid. Therefore, in the present invention, it is not necessary to add an additive such as a dispersant, and there is no adverse effect on the electrophotographic characteristics, that is, a decrease in sensitivity, an increase in residual potential, an increase in memory, etc.

Further, since the characteristics such as abrasion resistance and high hardness, which are generally possessed by the polycarbonate resin, are maintained, it is extremely effective in improving the mechanical durability by dispersing the fluororesin powder.

The content of the fluorine-based resin powder dispersed in the surface layer is appropriately 2 to 100% by weight, and particularly preferably 5 to 30% by weight, based on the fluorine atom-containing polycarbonate. Content rate is 2
If it is less than 100% by weight, the effect of modifying the surface layer by the dispersion of the fluororesin is not sufficient, while if it exceeds 100% by weight, the light-transmitting property is lowered and the mobility of the optical carrier is also lowered.

The constitution of the electrophotographic photosensitive member of the present invention is classified into the following four types.

1. Substrate / charge-generating layer / charge-transporting layer 2. Substrate / charge-transporting layer / charge-generating layer 3. Substrate / charge-generating agent + charge-transporting agent (single layer) 4. Substrate / photosensitive layer (1 to 3 or above) Still another form)
/ Protective layer In each case, the layer containing the fluorine atom-containing polycarbonate and the fluorine-based resin powder is at least the layer farthest from the substrate.

In the case of producing the electrophotographic photosensitive member of the present invention, as the conductive substrate, one having conductivity itself, for example, aluminum, aluminum alloy, copper, zinc, stainless steel, vanadium, molybdenum, chromium, titanium, nickel, indium. , Gold, platinum, and the like, and aluminum, aluminum aluminum alloy, indium oxide, tin oxide, acid value indium-tin oxide alloy, and the like, a plastic having a layer formed by a vacuum deposition method (for example, carbon black, It is possible to use a substrate in which plastics are coated with silver particles or the like) with a suitable binder, a substrate in which plastics or paper is impregnated with conductive particles, or a plastics having a conductive polymer.

An undercoat layer having a barrier function and an adhesive function can be provided between the conductive layer and the photosensitive layer. The undercoat layer is casein,
Polyvinyl alcohol, nitrocellulose, ethylene-
It can be formed of acrylic acid copolymer, polyvinyl butyral, phenol resin, polyamide (nylon 6, nylon 66, nylon 610, copolymerized nylon, alkoxymethylated nylon, etc.), polyurethane, gelatin, aluminum oxide and the like.

The film thickness of the undercoat layer is 0.1 to 40 microns, preferably 0.3 to 3 microns.

As a charge generating substance, selenium-tellurium, pyrylium, thiopyrylium dye, phthalocyanine pigment, anthanthrone pigment, dibenzpyrenequinone pigment, pyrantrone pigment, trisazo pigment, disazo pigment, azo pigment, indigo pigment, quinacridone pigment, asymmetric quinocyanine , Quinocyanine, etc. can be used.

Examples of the charge transport material include pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-N-
Phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N,
N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde- N, N-diphenylhydrazone, 1,3,3-trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-
Hydrazones such as diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p- Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)] -3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [6-methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[Lepidil (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-methyl-5 -(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3-
(Α-Methyl-p-diethylaminostyryl) -5-
(P-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline,
1-Phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pipazoline, pyrazolines such as spiropyrazoline, 2-
(P-Diethylaminostyryl) -6-diethylaminobenzoxazole, 2- (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2
-Chlorophenyl) oxazole and other oxazole compounds, 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole and other thiazole compounds,
Triarylmethane compounds such as bis (4-diethylamino-2-methylphenyl) -phenylmethane, 1,1-
Polyarylalkanes such as bis (4-N, N-diethylamino-2-methylphenyl) heptane and 1,1,2,2-tetrakis- (4-N, N-dimethylamino-2-methylphenyl) ethane Can be used.

As a method for dispersing the fluororesin powder, a general dispersing means,
That is, a homogenizer, ultrasonic waves, a ball mill, a vibrating ball mill, a sand mill, an attritor, a roll mill or the like can be used. After adding the fluorine resin powder to the fluorine atom-containing polycarbonate dissolved in a suitable solvent,
Disperse by the above dispersion method. If the charge transport layer is a surface layer, for example, a fluorine atom-containing polycarbonate and a charge transport substance are mixed in an appropriate amount in a solution to obtain a surface layer coating solution containing a fluorine resin. .

The coating can be performed using a coating method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a Meyer coating method, a blade coating method, a roller coating method, and a curtain coating method. Drying is preferably performed by drying by touching at room temperature and then drying by heating. The heat drying can be carried out at 30 ° C. to 200 ° C. for 5 minutes to 2 hours in a stationary state or under blowing air.

[Examples] Hereinafter, the present invention will be described more specifically with reference to Examples.

Example 1. An 80φ × 350 mm aluminum cylinder was used as a conductive substrate, on which a polyamide resin (trade name: Amilan CM-800
0, Toray) 5% methanol solution was applied by dipping method and 1
A μ thick subbing layer was provided.

Next, 10 parts by weight of disazo pigment having the following structural formula (parts by weight, the same applies hereinafter), polyvinyl butyral resin (trade name: S-REC)
BXL, Sekisui Kagaku Co., Ltd.) 6 parts and cyclohexanone 1
00 parts was dispersed for 20 hours by a side mill device using 1φ glass beads.

Tetrahydrofuran (50 to 100 parts (suitably)) was added to this dispersion and applied on the above-mentioned undercoat layer, followed by drying at 100 ° C. for 5 minutes to form a 0.15 μ thick charge generating layer.

Next, a fluorine atom-containing polycarbonate having the following structural formula, A tetrafluoroethylene resin powder (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.) was prepared as the fluororesin powder, and a hydrazone compound having the following structural formula was prepared as the charge transport substance.

First, 20 parts of the above-mentioned fluorine atom-containing polycarbonate is dissolved in 100 parts of cyclohexanone, 5 parts of the above tetrafluoroethylene resin powder is added thereto, and the mixture is mixed with a stainless steel ball mill to obtain 50 parts.
After time-dispersing, 20 parts of dichloromethane and 20 parts of the hydrazone compound were added to prepare a charge transport layer coating solution.
This coating solution was applied onto the charge generation layer and dried with hot air at 100 ° C. for 1 hour to form a charge transport layer having a thickness of 18 μm. This is referred to as a photoconductor 1.

On the other hand, for comparison, a photoreceptor was prepared in the same manner as in Example 1 except that the polycarbonate having the following structural formula was used as the charge transport layer binder. This is referred to as a photoconductor 2.

The photoconductors 1 and 2 thus prepared were mounted on a commercially available copying machine (NP-3525, manufactured by Canon Inc.), and image evaluation and durability evaluation were performed. The results are shown in Table 1.

As is clear from Table 1, in the photoconductor 1 of the present invention, the dispersibility of the tetrafluoroethylene resin powder is good, so that the image quality is high and the wear due to durable use is small. On the other hand, the photoconductor 2 for comparison has poor dispersibility of the tetrafluoroethylene resin powder,
Since the agglomerated particles are projected and projected on the surface of the photoconductor, the image becomes very rough. In addition, when the durability test is performed in such a surface state, there is a problem that toner is likely to adhere to the surface due to poor cleaning.

Next, the sample after the above durability test is subjected to high temperature and high humidity (32.5 ° C,
When the durability test was continued under the environment of 90% RH,
While a stable high-quality image was obtained up to 200,000 sheets, white spots and image deletion occurred on the photoconductor 2 from about 6,000 sheets. This is considered to be due to the occurrence of pinholes due to the presence of the aggregate of tetrafluoroethylene resin powder and the low resistance material accumulated in the irregularities on the surface.

Example 2 1 μm on an aluminum cylinder as in Example 1.
An undercoat layer of thick polyamide resin was formed.

Next, 15 parts of a pyrazoline compound having the following structural formula, 10 parts of bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Ltd.), 50 parts of monochlorobenzene and 10 parts of dichloroethane
Part, and this solution is dip-coated on the undercoat layer,
The film was dried at 1 ° C. for 1 hour to form a charge transport layer having a thickness of 15 μm.

Next, 2 parts of a bisazo pigment having the following structural formula, 4 parts of the tetrafluoroethylene resin powder used in Example 1 was added to 100 parts of a 10% monochlorobenzene solution of a fluorine atom-containing polycarbonate having the following structural formula, and dispersed with a stainless ball mill for 50 hours.

7 parts of the hydrazone compound used in the charge transport layer was dissolved in this dispersion to prepare a charge generation layer coating solution. This coating solution was applied to the cylinder by protrusion to form a charge generating layer having a thickness of 4 μm. This is the photoconductor 3.

On the other hand, for comparison, a photoconductor was prepared in the same manner as in Example 2 except that bisphenol Z-type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc.) was used as the binder of the charge generation layer. This is referred to as a photoconductor 4.

These photoreceptors were mounted on a copier by corona charging, negative toner development, and transfer charging, and the same evaluation as in Example 1 was performed. The results are shown in Table 2.

Example 3 1 μm on an aluminum cylinder as in Example 1.
An undercoat layer of thick polyamide resin was formed.

Next, 1 part of aluminum chloride phthalocyanine and Example 1
10 parts of the fluorine atom-containing polycarbonate used in 4 and 4 parts of vinylidene fluoride resin were dispersed with 45 parts of monochlorobenzene and 15 parts of tetrahydrofuran in a stainless ball mill for 50 hours, and 10 parts of the same hydrazone compound as in Example 1 was dissolved therein. Then, a photosensitive layer coating solution was prepared.

This coating solution was applied onto the undercoat layer by dip coating and dried at 100 ° C. for 1 hour to form a photosensitive layer having a thickness of 12 μm. This is photoconductor 5
And

On the other hand, for comparison, a photoreceptor was prepared in the same manner as in Example 3 except that polycarbonate A type (trade name Iupilon S-2000, manufactured by Mitsubishi Gas Chemical Co., Inc.) was used as the binder for the photosensitive layer. This is the photoconductor 6.

Example 4 1 μm on an aluminum cylinder as in Example 1.
An undercoat layer of thick polyamide resin was formed.

Next, 1 part of aluminum chloride phthalocyanine, 10 parts of bisphenol Z type polycarbonate (manufactured by Mitsubishi Gas Chemical Co., Inc.), 45 parts of monochlorobenzene and 15 parts of tetrahydrofuran were dispersed in a stainless ball mill for 50 hours, and the same hydrazone compound as in Example 1 was dispersed therein. A photosensitive layer coating solution was prepared by dissolving 10 parts.

Subsequently, this coating solution is dip-coated on the undercoat layer, and 100
It was dried at 1 ° C. for 1 hour to form a photosensitive layer having a thickness of 12 μm. Next, 10 parts of the fluorine atom-containing polycarbonate used in Example 2 and 5 parts of tetrafluoroethylene resin powder were dispersed together with 70 parts of monochlorobenzene for 5 hours with a paint shaker, and this dispersion was suddenly coated on the photosensitive layer. Then, a protective layer having a thickness of 2 μm was formed. This is the photoconductor 7.

On the other hand, for comparison, a photoconductor was prepared in the same manner as in Example 4 except that the bisphenol Z-type polycarbonate used in the photosensitive layer was used as the binder of the protective layer. This is referred to as a photoconductor 8.

These photoreceptors were evaluated in the same manner as in Example 1. The results are shown in Table 3.

As is clear from Table 3, since the surface layer fluororesin powder is extremely well dispersed in the photoreceptor of the present invention, it is possible to maintain high-quality image quality even during long-term durable use.

[Advantages of the Invention] The electrophotographic photosensitive member of the present invention, in which the fluororesin powder is dispersed very well in the surface layer, has excellent mechanical durability against the occurrence of surface abrasion and scratches due to rubbing. Have
It is stable even under high humidity, has good cleaning properties, and has no toner adhesion to the surface.

It is possible to always provide a high-quality image without the occurrence of coating film unevenness and pinholes on the surface and the accumulation of residual potential in repeated electrophotographic processes.

Claims (6)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a conductive substrate, wherein at least a layer most distant from the conductive substrate has at least one fluorine atom-containing polycarbonate and at least one fluorine resin powder. An electrophotographic photosensitive member characterized by containing one or more kinds: 2. The fluorine resin powder is tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin, An electrophotographic photosensitive member according to claim 1, which is a powder selected from the group consisting of: and a copolymer thereof. 3. The photosensitive layer has a laminated structure of a charge-generating layer and a charge-transporting layer, and the charge-generating layer and / or the charge-transporting layer contains one or more fluorine atom-containing polycarbonates. The electrophotographic photosensitive member according to claim 1, which contains one or more kinds of fluorine-based resin powders: 4. The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer comprises a single layer containing a charge generating substance and a charge transporting substance: 5. The electrophotographic photosensitive member according to claim 1, wherein the ratio of the fluorine-based resin powder to the fluorine atom-containing polycarbonate is 2 to 100% by weight: 6. The protective layer formed on the photosensitive layer, wherein the layer which is most distant from the conductive substrate and contains the fluorine atom-containing polycarbonate and the fluorine-based resin powder is a protective layer formed on a photosensitive layer. Electrophotographic photoreceptor: