JP2553558B2 - 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
% Of hydrogen as a modifier to reduce the localized state density (hereinafter referred to as a-Si: H) has been noticed and used because of its high photosensitivity, pollution-free properties, and high hardness. ing.

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.

Moreover, the charge density of surface charges is high 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 the actual photosensitivity is not sufficiently high. .

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.

Problems to be Solved by the Invention As means for solving such problems, Japanese Patent Laid-Open No. 54-
Japanese Patent No. 143645 discloses a function-separated type photoreceptor using an organic semiconductor material.

When formed on a photoconductive layer using this organic semiconductor material, it is expected to improve the charging potential by decreasing the dielectric constant, but since the organic semiconductor material has low hardness, it has an amorphous photoconductive film containing Si. The characteristics of a long-life photoreceptor with high hardness cannot be fully utilized. In addition, a temperature of 150 ℃ on conventional organic semiconductors
In order to form a good quality a-Si: H film as described above, a good electrophotographic photoreceptor cannot be obtained because of poor heat resistance. Alternatively, it has been proposed to subject polyacrylonitrile (PAN), which has heat resistance, to a ring-closing treatment by heating, but since sufficient carrier mobility and carrier lifetime have not been obtained, the residual potential is high and the sensitivity is high. Is not enough.

Means for Solving the Problems In order to solve the above problems, the present invention provides a function-separated photoreceptor in which a photoconductive layer and a charge transfer layer having the following structure are laminated, (N> 1, R: H , CH 3 O, C 2 H 5 O, CH 3, Cl) moreover year charge transfer layer wavenumber 30 is infrared absorption spectrum
Absorption at 24 ± 30 cm ^-1 A, 2913 ± 30 cm ^-1 B
And the integrated intensity ratio I _B / I _{A of} those absorptions is 0.1 ≦ I _B / I _A
Configure so that it falls within the range of ≦ 0.9.

The polymer layer having the following structure forms an intermediate usually called a precursor.

(N> 1, R: H, CH ₃ O, C ₂ H ₅ O, CH ₃ Cl) From the infrared absorption spectrum, the absorption A, 2913 due to the product vinylene bond at the position of 3024 ± 30 cm ^−1. Absorption B due to —CH ₂ — representing a precursor is observed at a position of ± 30 cm ⁻¹ . The amount of product increases and the integrated intensity ratio I _B / I _{A of} absorptions A and B decreases by applying heat treatment or the like. In the polymer layer having I _B / I _A of 0.1 or less, the resistance becomes too low, and the charging potential required for the photoconductor cannot be obtained.
On the other hand, when I _B / I _A is 0.9 or more, the residual potential remarkably increases, and a sufficient image cannot be obtained. I _B / I _A is 0.1 ≦ I _B / I _A ≦
By using a polymer layer having a ratio of 0.9 as the charge transfer layer, an electrophotographic photosensitive member having a small residual potential, high sensitivity and a large charging potential can be obtained.

Embodiment FIG. 1 schematically shows a cross section of an embodiment of the most basic electrophotographic photosensitive member according to the present invention.

The electrophotographic photoreceptor shown in FIG. 1 has a charge transfer layer 2 made of a polymer layer having a ring structure and a photoconductive layer 3 on a support 1 as an electrophotographic photoreceptor. 3 has on the one hand a free surface 4.

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 G
e _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 _1-z G
e _z ) _1-y C _y (: H: X) (0 <Y, Z <1), or a single layer of these layers. It can also be used when Y is continuously changed.

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

In the present invention, in order to further improve the electrophotographic characteristics, in FIG. 1, between the support 1 and the charge transfer layer 2, carriers injected from the support 1 into the charge transfer layer 2 are effectively blocked. Therefore, a barrier layer may be provided.

As a material for forming the barrier layer, Al ₂ O ₃ , BaO, BaO ₂ , B is used.
eO, 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 , Cu
O, Cu ₂ O, FeO, PbO, MgO, SrO, Ta ₂ O ₃ , ThO ₂ , ZrO ₂ , HfO ₂ , TiO ₂ , T
Metal oxides such as iO, SiO ₂ , GeO ₂ , SiO, GeO or TiN, AlN, Sn
N, NbN, TaN, metal nitride such as GaN, or metal carbide such as WC, SnC, TiC or insulator such as SiC, SiN, GeC, GeN, BC, BN,
Organic compounds such as polyimide, polyamide-imide and polyacrylonitrile are used.

Further, in order to improve the cleaning property, the abrasion resistance or the corona resistance, a surface coating layer is formed on the free surface 4 in FIGS. 1 and 2. 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 substances such as a layer containing hydrogen or halogen therein.

For producing 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 , SiHF ₃ , SiH
₂ F ₂ , SiH ₃ F, SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₃ Cl, etc. using a plasma CVD method using a source gas of Si atoms, or using polycrystalline silicon as a target, Ar and H ₂ (further F ₂ or Cl ₂ may be mixed) may be used for reactive sputtering in a mixed gas. In addition, a-Si _1-u C _u (: H: X) (0 <Y <1), a-Si
_1-u O _u (: H: X) (0 <Y <1), a-Si _1-u N _u (: H: X) (0
<Y <1) was prepared by further adding CH ₄ , C ₂ H ₆ , C as a carbon source.
₃ H ₈ , C ₄ H ₁₀ , C ₂ H ₄ , C ₃ H ₆ , C ₄ H ₈ , C ₂ H ₂ , C ₃ H ₄ , C ₄ H ₆ , C ₆ H ₆ etc.hydrocarbons, 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 F ₈ etc.
C ₆ H _6-m F _m (m = 1 to 6) C atom source gas such as benzene fluoride is mixed with silicon source gas used for plasma CVD, or Ar etc. is used for reactive sputtering. Used in combination with the sputtering gas. O ₂ , CO,
CO _2, NO, NO ₂ etc., As the nitrogen source used in a mixture N _2, NH _3, NO, and the like.

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 ₃ F, GeHCl ₃ , GeH ₂
A gas such as Cl ₂ , GeH ₃ Cl or the like can be mixed with the above-mentioned source gas of the Si atom to form by a plasma CVD method.

Further, in the present invention, the above-mentioned a-Si (: H: X) a-
Si _1-u C _u (: H: X) (0 <Y <1), a-Si _1-u O _u (: H: X)
(0 <Y <1), a-Si _{1-u Nu} (: H: X) (0 <Y <1),
Alternatively, conductivity can be controlled by adding impurities to these films to which Ge is added, and desired electrophotographic characteristics can be obtained. Examples of p-type impurities that give p-type conductivity include B, Al, Ga, and IN, which belong to Group IIIb of the periodic table, and B, Al, and Ga are preferably used to give n-type conductivity. The n-type impurities include N, P, A belonging to Group V b of the periodic table.
There are s, Gb, etc., and P, 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 Al, (C 2 H 5) 3 Al, (i-C
₄ H ₉ ) ₃ Al, (CH ₃ ) ₃ Ge, (C ₂ H ₅ ) ₃ Ga, InCl ₃ , (C ₂ H ₅ ) ₃ In
In the case of n-type impurities, 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, AsC
_{l 3, AsBr 3, SbH 3} , SbF 3, SbF 5, SbCl 3, the SbCl _5, etc. of gas or these gases H _2, the He, a gas diluted with Ar, the plasma CVD method, each of the film At the time of formation, it may be used by mixing with the above-mentioned source gas such as C atom and Si atom to be used. In the reactive sputtering method, Ar or H ₂ or
It may be used by mixing with F ₂ and Cl ₂ .

The charge transfer layer formed of a polymer material once forms a precursor and then has the following structure.

(N> 1, R: H , CH 3 O, C 2 H 5 O, CH 3, Cl) the infrared absorption spectrum, the absorption A, 2913 ± 30 cm due to the vinylene bond at the position of 3024 ± 30 cm ^-1 located precursor -CH structures ₂ ^-1 - have an absorption B due to, the integrated intensity ratio I _B / I _a thereof absorption due to the rate of formation of the products from the precursor. By carrying out a treatment such as heating, the reaction proceeds and the ratio of products increases. Integrated intensity ratio of this absorption I _B / I
_A charge transfer layer is formed by a polymer layer in which A is in the range of 0.1 ≦ I _B / I _A ≦ 0.9.

 Hereinafter, examples will be described.

Example 1 Poly (xylylene-α-diethylsulfonium bromide), which is one of polymer sulfonium salts, was coated on a mirror-polished aluminum substrate and formed into a film under reduced pressure at -30 ° C to obtain a polymer layer. This polymer layer was heat-treated in nitrogen gas at 200 to 400 ° C. for 1 to 15 hours. Thereby, at the same time as Br or (C ₂ H ₅ ) ₂ S of poly (xylylene-α-diethylsulfonium bromide) is dissociated, the degree of polymerization between these polymers is advanced and the length of the conjugated chain is increased. In addition, the optical bandgap decreased, and it was transparent (2.7 eV) without absorption in the visible region at first, but it is ~ 430 nm.
An absorption peak appears in the vicinity, and yellow (2.1 to 2.4 eV) colored poly (p-phenylene vinylene) is obtained.

This poly (p-phenylene vinylene) has the structure: X: it was _{C 2 H 2, n = 5~40} .

The infrared absorption spectrum of the polymer layer after this heat treatment is shown in FIG. At this time, absorption of 3024 ± 30 mc ^-1 A, 2913 ±
The integrated intensity ratio I _B / I _A of absorption B at 30 cm ^-1 was 0.56.

The thickness of the above layer as a charge transfer layer is 25μ after heat treatment.
The formed substrate is placed in a parallel plate type capacitively coupled plasma CVD apparatus having a 6-inch discharge electrode, the reaction vessel is evacuated to 5 × 10 ⁻⁶ Torr or less, and then the substrate is heated to 150 to 200 ° C. did. Next, SiH ₄ was introduced at 10-40 sccm, and
1.0Torr, high frequency power 20 ~ 100W, non-dope
d) 0.5 to 5 μm of a-Si: H layer is formed as a photoconductive layer, SiH ₄ is introduced at 10 to 30 sccm, C ₂ H ₄ is introduced at 20 to 40 sccm, and pressure is applied.
Si _1-X C _X : H (0 <at 0.2 ~ 1.0 Torr, high frequency power 50 ~ 150 W
An electrophotographic photosensitive member was prepared by forming 0.08 to 0.3 μm with X <1) as the surface coating layer.

When the electrophotographic photoreceptor thus obtained was corona-charged at +6.0 KV, a surface potential of +2200 V was obtained, and when exposed to white light, the residual potential was +50 V or less and the half-potential exposure was 1 lux.・ It was obtained with very high sensitivity of less than sec. When the photoreceptor was charged to +900 V and exposed to white light, the half-reduction potential exposure was 0.2 lux.
・ Sensitivity is very high, below sec. This is the conventional a-Si: H
Has a sensitivity of 3 times as compared with the case where a photoreceptor made of 20 μm of is charged to +400 V and exposed with white light, and when exposed to only visible light again and compared, a sensitivity of 4 times or more was confirmed. . In addition, when charged at the same corona potential, a-
Compared with Si: H alone, it was shown that the charging potential was 4 times or more, and a high-sensitivity photoconductor could be obtained with a small charging current.

Further, oxygen is added to the a-Si: H photoconductive layer of 0.2 to 2 μm for 200 to 200 μm.
An electrophotographic photoreceptor having the same characteristics as described above was formed both when 3,000 ppm was added and when B was added in an amount of 0.5 to 5 ppm.

On the other hand, the integrated intensity ratio I _B / I _A of the absorption A and the absorption B of the infrared absorption spectrum of the polymer layer in the insufficient heat treatment state is 1.1.
Therefore, in the photoconductor obtained by using this polymer layer, the residual potential was high and a sufficient image density could not be obtained. Again 50
Those subjected to heat treatment at 0 ° C. for 5 hours have a significantly reduced charging potential.

Example 2 A surface-polished aluminum drum was coated with a sulfonium salt having the following structure and dried to form a film, thereby obtaining a polymer layer.

This polymer layer was heat-treated in vacuum at 150 to 300 ° C. for 1 to 20 hours. The integrated intensity ratio I _B / I _A of absorptions A and B in the infrared absorption spectrum of the polymer layer thus obtained was 0.42.

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, the reaction vessel was evacuated to 5 × 10 ⁻⁶ Torr or less, and then the aluminum drum was heated to 150 to 200 ° C. Heated to. SiH ₄ 50 to 150 sccm, C ₂ H _{2 2} to 10 sccm, B ₂ H ₆ to SiH _{4 5} to 100 ppm, pressure 0.2 to 1.0
Torr, a-Si _1-X C _X : H layer 1-5 with high frequency power 100-250W
Then, C ₂ H ₂ in addition to SiH ₄ was increased to ₂₀ to 50 sccm to form an a-Si _1-X C _X layer 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 is 1.7 to 1.9 eV, and this photoconductor was mounted on an optical printer using a 670 nm LED as a light source, and it was +500 to + when positively charged. 8
A clear print was confirmed at a surface potential of 00V.

In addition, a- (Si _1-Z Ge _Z ), in which Ge is added to a-Si _1-X C _X : H
_The sensitivity was further improved by using _1-X C _X : H.

As a surface coating layer as an alternative material to the a-Si _1-X C _X 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.

EFFECTS OF THE INVENTION In the electrophotographic photoreceptor according to the present invention, when the photoconductive layer that generates movable carriers by photoexcitation is laminated on the charge transfer layer, the charge transfer layer is in a precursor state by applying heat treatment or the like. To form a polymer layer. At this time,
Integral intensity ratio of absorption A and absorption B in infrared absorption spectrum I _B / I
_By setting _A to 0.1 ≦ I _B / I _A ≦ 0.9, it becomes possible to form a charge transfer layer having a large carrier mobility and a relatively high resistance.

Due to the above effects, an electrophotographic photoreceptor having a small residual potential, high sensitivity, and a large charging potential can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic photosensitive member according to an embodiment of the present invention, and FIG. 2 is an infrared absorption spectrum diagram of a charge transfer layer poly (p-phenylene vinylene) according to the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Support, 2 ... Charge transfer layer, 3 ... Photoconductive layer, 4
…… free surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Akiyama 1006 Kadoma, Kadoma-shi, Matsushita Electric Industrial Co., Ltd. (72) Inventor Masanori Watanabe 1006 Kadoma, Kadoma-shi, Matsushita Electric Industrial Co., Ltd. (56) References JP-A-63-276058 (JP, A) JP-A-1-142556 (JP, A) JP-A-63-218961 (JP, A) JP-A-63-274959 (JP, A) JP-A-59-133552 (JP, A) JP-A-48-54944 (JP, A) JP-A-57-212203 (JP, A)

Claims (7)

(57) [Claims] 1. An electrophotographic apparatus comprising a photoconductive layer for generating movable carriers by photoexcitation and a charge transfer layer for effectively injecting the carriers and capable of effectively moving from the injection surface to the opposite surface. In the photoreceptor, the charge transfer layer contains a polymer having the following structure, Position of: (n> 1, R H , CH 3 O, C 2 H 5 O, CH 3, Cl) and its infrared absorption spectrum is absorbed in the position of ^{3024 ± 30cm -1 A, 2913 ±} 30cm -1 And an integrated intensity ratio I _B / I _{A of the} absorptions in the range of 0.1 ≦ I _B / I _A ≦ 0.9. 2. The electrophotographic photosensitive member according to claim 1, wherein the photoconductive layer has an amorphous layer containing a modifier that reduces the localized density of states. 3. AsF ₅ , S as an electron acceptor in the charge transfer layer
The electrophotographic photosensitive member according to claim 1, wherein 0.01 to 0.4 wt% of O ₃ , SbF ₅ , Br ₂ , I ₂ , and TCNQ is added. 4. The electrophotographic photosensitive member according to claim 2, wherein the photoconductive layer contains at least either hydrogen or a halogen element. 5. The electrophotographic photosensitive member according to claim 1, wherein heat treatment is performed after or during the formation of the polymer layer which is the charge transfer layer. 6. When heat treatment is applied to the charge transfer layer, air, Ar,
The electrophotographic photosensitive member according to claim 5, which is carried out in an atmosphere of H ₂ , N ₂ , O ₂ or in a vacuum. 7. The electrophotographic photosensitive member according to claim 1, which has a surface coating layer on its free surface.