JPH0823706B2 - Method for manufacturing electrophotographic photoreceptor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrophotographic photosensitive member used in an electrophotographic copying machine, an optical printer or the like.

Conventional technology 10 to 40 atm as photoconductor in electrophotographic photoreceptor
Amorphous silicon (hereinafter referred to as a-Si: H) containing% hydrogen as a modifier that reduces the localized density of states has attracted attention due to its high photosensitivity, pollution-free property, and high hardness. Has been done.

However, there are still many problems to be solved in the electrophotographic photosensitive member composed of a-Si: H.

For example, as a first problem, a-Si: H is an organic photo-semiconductor (hereinafter referred to as OPC) which is another photosensitive material, or Se.
Compared with the above, the dielectric constant is as large as about 11 (OPC: about 3, Se: about 6), and the electrostatic capacity is large, so a very large charging current is required when the surface is charged.

Further, the surface charge has a high charge density to obtain a practical surface potential (up to 400 V), and a large amount of light energy is required to photo-eliminate this charge, so it can be said that the actual photosensitivity is sufficiently high. Absent.

Further, as the second problem, in the plasma CVD method using a silane (referred to as SiH ₄ ) gas, which is most often used for forming an a-Si: H film, as a source gas, the deposition rate is slow at 10 μm / H or less, and the silane gas Since it is expensive, it is difficult to reduce the manufacturing cost.

The third problem is that the film thickness is often less than 30 μm, and the charging electric field strength is about 30 V / μm.
Since the surface potential for practical use is as low as 500 V or less as compared with 800 V of the Se photoconductor, there is a problem that a usual two-component developer cannot obtain a copy having a sufficient image density.

On the other hand, also in OPC, the function-separated type becomes the mainstream and the sensitivity,
It is also surpassing the Se photoconductor in its life.

The OPC photoreceptor uses a charge generation layer, a charge transfer layer, a surface layer or an undercoat layer at the interface between the support and the charge generation layer, and most of them are formed by a manufacturing method.

Further, in order to overcome the drawbacks of a-Si: H, OPC is used as a charge transfer layer and a-Si: H is used as a photoconductive layer.
Japanese Patent No. 43645 discloses a function-separated type photoreceptor using an organic semiconductor material and a-Si: H, but even in this case, a coating method is mainly used.

Problems to be Solved by the Invention It is difficult for the coating method to coat a large area on a substrate having various shapes with a uniform film thickness, and it is also difficult to obtain a thick film of 20 μm or more. In addition, since the equipment for coating is expensive and the equipment burden is imposed, the photoreceptor is also expensive.

A main object of the present invention is to provide an inexpensive photoconductor that does not require a coating device.

Means for Solving the Problems In an electrophotographic photoreceptor in which a photoconductive layer and a charge transfer layer containing a polymer film as a main component are laminated, the charge transfer layer contains poly (p-phenylene) sulfide as a main component. Action to be formed by fusion with heat treatment as polymer film Polymer film mainly composed of poly (p-phenylene) sulfide has ring structure (phenylene) and VIb group element S in para position in main chain It has a linear chain structure and has a melting point at ~ 280 ° C.

In addition, although the carrier mobility is as large as 10 ⁻⁴ to 10 ⁻⁷ cm ² / V · sec, the carrier life is short, and conventionally, sufficient characteristics cannot be obtained as a charge transfer layer of an electrophotographic photoreceptor.

Further, even for a photoconductive layer having a small ionization potential and a small optical bandgap such as a-Si: H, the injection efficiency of holes or electrons was poor and the residual potential was large.

Further, these are difficult to dissolve in various solvents, and it is difficult to form them on any substrate.

However, these films are adhered to the conductive substrate directly or via a silane coupling agent, and
To easily form a uniform charge transfer layer by softening and fusing the polymer film by heat treatment in air or oxidizing active gas for 0.1 to 15 hours at 200 to 350 ° C. I was able to.

At the same time, an oxidation reaction is induced in these polymer layers,
The range of holes (μτ product) in the charge transfer layer was improved, and high-sensitivity electrophotographic photoreceptor characteristics with a small residual potential could be obtained.

Due to the above synergistic effect, an electrophotographic photosensitive member having a small residual potential, a high sensitivity, and a large charging potential can be easily obtained at low cost without using a coating device.

Example FIG. 1 schematically shows a cross section of an example of a basic electrophotographic photosensitive member according to the present invention.

The electrophotographic photosensitive member shown in the figure has a charge transfer layer 2 made of a polymer film and a photoconductive layer 3 on a support 1 as the electrophotographic photosensitive member, and the photoconductive layer 3 is a free surface on the one hand. Have four.

In the present invention, an amorphous layer containing silicon having high hardness is used as the photoconductive layer, and a-Si (: H: X), a-
Si _1-y C _y (: H: X) (0 <y <1), a-Si _1-y O _y (: H:
X) (0 <y <1), a-Si _1-y N _y (: H: X) (0 <y <
1), a-Si _1-z Ge _z (: H: X) (0 <z <1), a- (Si
_1-z Ge _z ) _1-y N _y (: H: X) (0 <y, z <1), a- (Si _1-z
Ge _z ) _1-y O _y (: H: X) (0 <y, z <1), or a- (Si
A single layer of _1-z Ge _z ) _1-y C _y (: H: X) (0 <y, z <1) or a stacked layer of these can be used. Further, it is also possible to use a case where y is continuously changed.

At this time, the thickness of the charge transfer layer is 5 to 50 μm, preferably
The thickness of the photoconductive layer may be 0.5 to 10 μm, preferably 1 to 5 μm.

In the present invention, in order to further improve the electrophotographic characteristics, in the figure, a barrier between the support 1 and the charge transfer layer 2 is provided to effectively block carriers injected from the support 1 into the charge transfer layer 2. Layers may be provided.

As the material for forming the barrier layer, Al ₂ O ₃ , BaO, Ba
_{O 2, BeO, Bi 2 O} 3, CaO, CeO 2, Ce 2 O 3, La 2 O 3, Dy
₂ O ₃ , Lu ₂ O ₃ , Cr ₂ O ₃ , CuO, Cu ₂ O, FeO, PbO, MgO, S
rO, Ta ₂ O ₃ , ThO ₂ , ZrO ₂ , HfO ₂ , TiO ₂ , TiO, SiO ₂ , GeO
₂ , metal oxides such as SiO, GeO or TiN, AlN, SnN, NbN,
Metal nitride such as TaN, GaN, metal carbide such as WC, SnC, TiC, or insulator such as SiC, SiN, GeC, GeN, BC, BN, heat resistance of polyimide, polyamide imide, polyacrylonitrile, etc. An organic compound having is used.

In addition, a surface coating layer is formed on the free surface 4 in the figure in order to improve cleaning property, abrasion resistance, or corona resistance. Suitable materials for the surface coating layer include Si _x O _1-x , Si _x C _1-x , Si _x N _1-x , Ge _x O _1-x , Ge
_x C _1-x , Ge _x N _1-x , B _x N _1-x , B _x C _1-x , Al _x N _1-x (0
<X <1), and inorganic materials such as carbon and layers containing hydrogen or halogen therein.

For forming a-Si (: H: X), which is a photoconductive layer containing silicon, SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl ₄ , SiH
Si such as F ₃ , SiH ₂ F ₂ , SiH ₃ F, SiHCl ₃ , SiH ₂ Cl ₂ and SiH ₃ Cl
Plasma CVD method using atomic source gas, or targeting polycrystalline silicon, Ar and H ₂ (further F ₂ or Cl
Reactive sputtering in a mixed gas of ₂ may be used) is used. In addition, a-Si _1-y C _y (: H: X) (0 <y
<1), a-Si _1-y O _y (: H: X) (0 <y <1), a-Si
_To prepare _1-y N _y (: H: X) (0 <y <1), CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ and C ₂ H ₄ were further added as carbon sources. , C
Hydrocarbons such as ₃ H ₆ , C ₄ H ₈ , C ₂ H ₂ , C ₃ H ₄ , C ₄ H ₆ and C ₆ H ₆ , CH ₃ F, CH ₃ Cl, CH ₃ I, C ₂ H ₅ Cl , C ₂ H ₅ Br, etc., allyl halides, CClF ₃ , CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃
Fluorocarbon gas such as F ₈ or C ₆ H _6-m F _m (m = 1 to 6) source gas of C atom such as fluorinated benzene is mixed with a silicon source gas used in the plasma CVD method or is reactive. The sputtering method is used by mixing with a sputtering gas such as Ar. Further, as an oxygen source, O ₂ , CO, CO ₂ , NO, NO _2, etc.,
As the nitrogen source, N ₂ , NH ₃ , NO or the like is mixed and used.

Also, when Ge is added to a-Si (: H: X), GeH ₄ , Ge
₂ H ₆ , Ge ₃ H ₈ , GeF ₄ , GeCl ₄ , GeHF ₃ , GeH ₂ F ₂ , GeH
A gas such as ₃ F, GeHCl ₃ , GeH ₂ Cl ₂ or GeH ₃ Cl may be mixed with the above Si atom source gas to form the plasma CVD method. Furthermore, in the present invention, the above aS
i (: H: X), a-Si _1-y C _y (: H: X) (0 <y <1), a-S
i _1-y O _y (: H: X) (0 <y <1), a-Si _1-y N _y (: H:
X) (0 <y <1) or by adding impurities to these films with Ge added thereto, conductivity can be controlled and desired electrophotographic characteristics can be obtained. Examples of p-type impurities that impart p-type conductivity include B, Al, Ga, In, and the like belonging to Group IIIb of the periodic table, and preferably B, Al, Ga.
Is used as an n-type impurity that imparts n-type conductivity,
There are N, P, As, Sb, etc. belonging to Group V b of the periodic table, and P and As are preferably used.

Further, as a method of adding these impurities, in the case of p-type impurities, B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆
H ₁₂ , B ₆ H ₁₄ , BF ₃ , BCl ₃ , BBr ₃ , AlCl ₃ , (CH ₃ ) ₃ A
_{l, (C 2 H 5)} 3 Al, (i-C 4 H 9) 3 Al, (CH 3) 3 Ga,
_{(C 2 H 5) 3 Ga} , InCl 3, a _{(C 2 H 5) 3 In} , the case of n-type _{impurity, N 2, NH 3, NO} , N 2 O, NO 2, PH 3, P 2 H ₄ , P
_{H 4 I, PF 3, PF} 5, PCl 3, PCl 5, PBr 3, PBr 5, PI 3, AsH 3,
_{AsF 3, AsCl 3, AsBr 3} , SbH 3, SbF 3, SbF 5, SbCl 3, SbCl 5
Etc., or a gas obtained by diluting these gases with H2, He, and Ar, in the plasma CVD method, is mixed with the above-mentioned raw material gas such as C atom and Si atom to be used in forming each film. It may be used, and in the reactive sputtering method, it may be used by mixing with Ar or H ₂ , or F ₂ and Cl ₂ .
Examples will be described below.

Example 1 On a mirror-polished 15 cm square aluminum substrate, a 15 μm poly (p-phenylene) sulfide polymer film was adhered and the end was fixed, and in air, at a temperature of 280 to 360 ° C.
It was heated for 0.1 to 0.5 hours to form a charge transfer layer. This substrate was placed in a parallel plate type capacitively coupled plasma CVD apparatus having a 6-inch discharge electrode, and the inside of the reaction vessel was set to 5
After evacuating to × 10 ^-6 Torr or less, the substrate was heated to 150 to 200 ° C. Next, SiH ₄ was introduced at 10 to 40 sccm and the pressure was 0.2 to 1.0 Torr.
r, high frequency power of 20 to 100 W, and 0.5 to 5 ppm of B added aS
The i: H layer is formed as a photoconductive layer in a thickness of 0.5 to 5 μm, and SiH ₄
Of 10 to 30 sccm and C ₂ H ₄ of 20 to 40 sccm, and pressure of 0.2 to
Si _1-x C _x : H (0 <x <at 1.0 Torr and high frequency power 50-150W
1) was formed as a surface coating layer to 0.08 to 0.3 μm to prepare an electrophotographic photosensitive member.

When the electrophotographic photoreceptor thus obtained was corona charged at +6.0 kV, a surface potential of +1200 V was obtained, and when exposed to white light, the residual potential was +450 V or less and the half-potential exposure was 10 lux.・ High sensitivity of less than sec was obtained.

Next, a film containing 0.04 to 0.1% by weight of TCNQ (7,7,8,8, tetracyanoquinodimethane) as an electron acceptor was added.
The polymer film was formed to a film thickness of 0 μm. This was subjected to heat treatment at 250 to 280 ° C. for 0.5 to 5 hours in the same manner as above, and was fused to the substrate to form a charge transfer layer.

Further, an a-Si: H layer having a thickness of 0.5 to 5 μm is formed as a photoconductive layer, and Si _1-x C _x : H (0 <x <1) is formed as a surface coating layer to have a thickness of 0.08 to 0.3 μm. To produce an electrophotographic photoreceptor.

When this photoreceptor was charged to +900 V and exposed to white light as well, the half-potential exposure amount was 1.0 lux · sec or less, and the sensitivity was greatly improved. Comparing this with the conventional case where a photoreceptor of 20 μm of a-Si: H was charged to +400 V and exposed with white light, the same level of sensitivity was confirmed. It was also shown that charging with the same corona potential can provide a highly sensitive photoreceptor with a charging current that is four times or more smaller than that of a-Si: H alone.

Also, carbon is 2 to 30 atm% in the a to Si: H layer of 0.2 to 2 μm.
A photoconductive layer was formed by using a source gas in which Si _1-x C _x : H was added and hydrogen or He gas was sufficiently diluted to 5% or less. In this case, an electrophotographic photosensitive member having a small residual potential of 50 V or less could be formed.

Example 2 A surface-polished aluminum drum substrate was covered with a cylindrical poly (p-
The silane coupling agent is applied to the inner surface of the phenylene) sulfide film and attached.

A typical compound of the silane coupling agent used in the present invention is an organic silane compound represented by the general formula R _n Si _4-n . However, R: organic substituent, X: hydrolyzable substituent, n:
Indicates an integer of 1 to 3.

The substituent R is an arbitrary substituent such as aliphatic, aromatic, cycloaliphatic, and heteroaromatic, and at least one of them has an active group such as an alkyl group, an olefinic group, a glycidyl group, and a mercapto group. A group, an amino group, an alkyl group having an epoxy group, or an alkaryl group.

On the other hand, X indicates hydrolyzability. For example, halogen, an amino group, a hydroxy group, and an alkoxy group having 1 to 4 carbon atoms.

When the drum substrate is cooled in a dry atmosphere and the outer diameter of the drum, which has been reduced by heat shrinkage, is inserted into PPS and the temperature is raised to room temperature, the surface coated with the silane coupling agent makes close contact with the substrate, and the drum-shaped substrate Also in the above, the charge transfer layer can be covered with an initial uniform film thickness.

Such a drum substrate in oxygen at 200 ~ 260 ℃ 0.
It was heated and fused for 5 to 10 hours. The PPS in this state became brownish and the optical band gap was ~ 2.4 eV.

This was placed in a capacitively coupled plasma CVD apparatus having a cylindrical discharge electrode with a length of 45 cm and an inner diameter of 16 cmΦ, and after evacuation of the reaction vessel to 5 × 10 ⁻⁶ Torr or less, the aluminum drum was heated to 150 to 200 ° C. Heated to. SiH ₄ 50-150sccm, C ₂ H
₂ to 2-10 sccm, B ₂ H ₆ to SiH _{4 5} to 100 ppm, H ₂
1000-1500sccm, pressure 0.2-1.0Torr, high frequency power 100-2
An a-Si _1-x C _x : H layer is formed as a photoconductive layer at 50 W for ₁ to 5 μm, and then C ₂ H ₂ is increased to ₂₀ to 50 sccm for SiH ₄ ,
With H ₂ at 100 sccm, an a-Si _1-x C _x layer as a surface coating layer was formed in an amount of 0.05 to 0.5 μm to obtain an electrophotographic photoreceptor. At this time, the optical bandgap of the a-Si _1-x C _x : H layer was 1.7 to 1.9 eV.

This photoconductor was mounted on an optical printer using a 670 nm LED as a light source, and clear printing was confirmed at a surface potential of +500 to 800 V when positively charged. The residual potential of this drum is + 100-200V
Met.

In addition, a- (Si _1-z G obtained by adding Ge to a-Si _1-x C _x : H
The sensitivity was further improved by using e _z ) _1-x C _x : H.

As a material to replace the a-Si _1-x C _x layer as a surface coating layer
When 0.1 to 0.5 μm of a-Ge _1-x C _x : H (0 <x <1) was formed by the plasma CVD method and mounted on an optical printer in the same manner, the electrophotographic photosensitive member of this structure showed heat resistance, It was confirmed that it has excellent moisture resistance and has a printing durability of 500,000 sheets.

In addition, TCNQ as an electron acceptor in the PPS polymer layer is 0.02-
By adding 0.1wt%, the residual potential becomes 50 ~ 90V.
And a small electrophotographic photoreceptor was obtained.

EFFECTS OF THE INVENTION According to the present invention, when a photoconductive layer that generates movable carriers by photoexcitation is laminated on a charge transfer layer, the charge transfer layer is formed by fusion by heat treatment, so that heat resistance is improved. It is possible to form a charge transfer layer having an excellent carrier and a large μτ product with a uniform film thickness and without using a coating apparatus.

Due to the above synergistic effect, an electrophotographic photosensitive member having a small residual potential, high sensitivity and a large charging potential can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic photosensitive member manufactured according to an example of the present invention. DESCRIPTION OF SYMBOLS 1 ... Support, 2 ... Charge transfer layer, 3 ... Photoconductive layer, 4
...... Free surface,

Front page continuation (72) Inventor Koji Akiyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Chisato Sakahara Osaka, Kadoma City, Osaka Prefecture Person Masanori Watanabe 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-60-59353 (JP, A) JP-A-55-90954 (JP, A) JP-A-58-98735 (JP, A) JP 58-80646 (JP, A) JP 45-10273 (JP, B1)

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising a photoconductive layer and a charge transfer layer comprising a polymer film as a main component, which is laminated on a conductive support, wherein the charge transfer layer comprises poly (p-phenylene) sulfide. A method for producing an electrophotographic photosensitive member, comprising a step of forming a polymer film as a main component by fusion by heat treatment. 2. The method for producing an electrophotographic photosensitive member according to claim 1, wherein an electron acceptor is added to the polymer film which is the charge transfer layer. 3. The method for producing an electrophotographic photoreceptor according to claim 1, further comprising the step of forming an amorphous layer containing a modifying substance in which the photoconductive layer reduces the density of localized states. 4. The method for producing an electrophotographic photosensitive member according to claim 1, further comprising the step of forming a surface coating layer on the free surface.