JPS63239459A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the mechanical life and durability of a photosensitive body by forming an interlayer made of a specified material between a photosensitive layer and a protective layer. CONSTITUTION:The electrophotographic sensitive body is formed by successively laminating on a conductive substrate 4 a photosensitive layer 3, the interlayer 2 made of an organometallic complex, such as a silyl isocyanate material, alkoxy-containing silicone resin, or Zr-acetylacetone, a mixture of the organometallic complex and a silane coupling agent, or an inorganic material, such as a silicon compound of a-SiC or the like, or a boron compound, such as a-BN, and the protective layer 1. The interlayer 2 has a volume resistivity rho, a ratio of a forward current J per unit volume to an applied electric field E of a photosensitive body, and a ratio of forward current to reverse current I1/I2, each satisfying the following expressions: 10<12>OMEGA.cm<=rho<10<14>OMEGA.cm, 10<-13>(A/ V.cm)>J/E, and I1/I2<=1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electrophotographic photoreceptor, and more particularly to an improvement in an electrophotographic photoreceptor having a protective layer on the surface of a photoconductive layer.

[Prior Art] Many photoreceptors have been put into practical use for use in electrophotography, which includes charging, exposure, development, transfer, and cleaning processes.

For example, in inorganic materials, se and 5e-Te alloys, 3
Examples include vapor deposited films such as e-A3 alloy. On the other hand, in the case of organic materials, a charge transfer layer containing a triphenylamine-based or hydrazone-based charge transfer agent is formed on a charge generation layer in which organic pigments such as azo pigments, cyanine pigments, and phthalocyanine pigments are dispersed in an organic binder. A laminated photoreceptor, etc., is used.

These photoreceptors have a problem in that image defects occur on copies due to scratches, dents, etc. during handling, which significantly shorten the lifespan of these photoreceptors before their original characteristic lifespan. or,
Due to the exposed surface of the photosensitive layer, cleaning failures may occur due to incompatibility between the surface properties of the photoconductor and the properties of the toner, and especially when used for long periods of time due to the photosensitive layer being composed of organic matter for organic photoconductors. The occurrence of wear is also an important issue that needs to be improved.

To solve these problems, it has been proposed to provide a protective layer on the surface of the photosensitive layer.

In particular, in a laminated photoreceptor, the protective layer improves mechanical durability, and the intermediate layer improves charge retention and adhesion. In this case, the electrical properties of the intermediate layer and the protective layer greatly influence the electrophotographic properties, and the range thereof is extremely narrow. The protective layer should be 10+s~1012Ω・C1
1I, and the resistance value can be set relatively easily by dispersing the metal oxide. Therefore, for example, a technique has been developed to increase the thickness of the protective layer in order to improve the strength of the protective layer, and to prevent capri on copies due to residual potential by incorporating a resistivity reducing agent into the film (Japanese Patent Laid-Open No. 53-3338). Alternatively, a protective layer with high mechanical strength is provided with a thickness of 0.5 to 2μ to improve the durability of the photoreceptor (Japanese Patent Application Laid-open No. 61-511
55) etc. are known.

However, in a photoreceptor having such a surface protective layer,
There has never been a photoreceptor that has achieved a longer lifespan by eliminating fundamental drawbacks such as high residual potential and increased residual potential as copying cycles are repeated, peeling of the protective layer, and environmental resistance.

Furthermore, since the intermediate layer cannot be made thick due to residual potential, it must be made of a material that can be formed into a thin layer and has a relatively low resistance. Furthermore, the photosensitive layer must satisfy conditions such as not being deteriorated by the intermediate layer material and being easy to manufacture.

[Objective] The present invention is a photoreceptor having a surface protective layer and an intermediate layer on a photosensitive layer, which eliminates the above-mentioned drawbacks, has a long mechanical life, is highly durable, and has a low residual potential. An object of the present invention is to provide a photoreceptor that can always make clear copies without increasing residual potential due to repeated copying.

[Configuration] The present invention has been made to achieve the above object,
In an electrophotographic photoreceptor in which a photosensitive layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, the intermediate layer is composed of a silyl isocyanate-based material, an alkoxy group-containing silicone resin, an organometallic complex, and a combination of an organometallic complex and silane coupling. The electrophotographic photoreceptor is characterized in that it is made of at least one of a mixture or an inorganic material such as a silicon compound or a boron compound.

In particular, it is suitable that the intermediate layer has the following characteristics.

■ Volume resistivity ρ is 1012Ω・cm≦f<10”
Ω・Cl11, ■ The ratio of forward current (J) per unit volume to the applied electric field (E) of the photoreceptor is 1F'' (A/V -cm) > J / E tear, ■ Forward vs. reverse direction. Current ratio ■+ /I 2 is I
+/I 2≦1.

The structure of the electrophotographic photoreceptor of the present invention is shown in FIG. 1. 1 is a transparent protective layer made of an organic polymer compound in which fine particles of tin oxide are dispersed, 2 is an intermediate layer having the above characteristics, and 3 is a transparent protective layer made of an organic polymer compound in which fine particles of tin oxide are dispersed. 4 is a photosensitive layer, and 4 is a conductive support.

As the silyl isocyanate compound used in the intermediate layer, there are generally the following compounds where R is a functional group.

Alkylsilyl isocyanate type Rns i (NCO>4-n and its condensate alkoxysilane isocyanate type (RO)n Si (NGO>4-r+ and its condensate) Tetraisocyanate type S i (NCO)4 and its condensate In the above, n=1 to 3, and specific functional groups for R include the following.

Hydrocarbon groups: methyl group, ethyl group, butyl group, octyl group, octadecyl group, phenyl group, benzyl group, etc. Unsaturated groups: vinyl group, acrylic group, allyl group, methacryl group, etc. Alkoxy group: ethoxy group, propoxy group, Specific examples of compounds such as phenoxy groups include the following.

Trimethylsilylinocyanate dimethylsilyl isocyanate methylsilyl isocyanate vinylsilyl isocyanate phenylsilyl isocyanate tetraisocyanate silane ethoxysilane triisocyanate 1 ~ The silyl isocyanate compound is s r-NG as described above.
It has an O bond and forms a silicon oxide film through a moisture decomposition reaction as described below.

-3i -NCO+2H20 →-81-OH+NH] +CO2 -3i -OH+-3i -OH →[S i -0-3i ] n Therefore, a silicon oxide film forming agent can be produced using a compound having a 3i-NGO bond as a basic component. . Alkyl silicates, organic polymers, and inorganic polymers can also be used if necessary. Further, metallosiloxane bonds can be formed by adding titanium, zirconium, tin, aluminum, antimony, etc.

Further, examples of the organometallic complex include zirconium acetyl acetone, zirconium butoxide, titanium butoxide, and the like.

Inorganic materials include a-3i C, a-3i N, a-s
+o, a-sN, etc. are mentioned.

The present invention was made based on the discovery that an intermediate layer with excellent properties can be formed by utilizing the properties of these materials.

These compounds can be used alone or as a mixture of two or more. Further, in order to improve adhesion, a mixture with other organic compounds and, if necessary, a catalyst may be added.

The properties of the intermediate layer defined above are preferable for the present invention, because if ρ is less than 1012 Ω·cm, the charging ability as an electrophotographic photoreceptor cannot be maintained and the desired image density cannot be obtained. On the other hand, when ρ exceeds 10"Ω・Cm, the charging ability is sufficiently satisfied, but the residual potential increases, causing background stains, and furthermore, the accumulation of electrons generated by exposure during repeated use occurs, resulting in a decrease in the dark potential. Since the amount is large compared to the case without the overcoat layer, the image density is greatly reduced. Therefore, the above range is appropriate, and ρ on the order of 10 12 to 10 13 Ω·cm is appropriate for the waiting time.

Also, J/E should be less than 10-1 Go A/V -cm+
) It is necessary to prevent charge injection into the photosensitive layer to some extent. The charging ability decreases as J/E increases.

For example, 6.3x10- +) A/V-cm Teha band i
[The position is around 172, making it impractical.

Furthermore, the forward and reverse current ratio needs to be 1 or less. That is, it is desirable to exhibit voltage-current characteristics similar to those of an insulating layer to N-type voltage-current characteristics. This blocks electrons generated by light injection (if electrons are blocked, discharge is relatively easy if ρ is 1012 to 10I4Ωcm), but if the forward current is large, the overcoat layer is As a result, the amount of discharged electrons also increases.

The above-mentioned requirements for the intermediate layer mainly apply to photosensitive materials.
This article describes the use of chalcogen-based materials such as AS-based (particularly As2Se2), 5eTe-based, and Se-based materials, but it can also be applied to photosensitive materials other than a-3i;l-1 and OPC-based chalcogen materials. Applicable.

The thickness of the intermediate layer can be arbitrarily set, but it is preferably 10 μm or less, preferably 1 μm or less, particularly 0.5 μm or less. The intermediate layer can be formed by a method such as a dipping method, a spray method, or a vapor phase method.

The photoconductive layer of the photoreceptor of the present invention includes a vacuum-deposited film of 3e, 3e-Te alloy, or 3e-AS alloy, and a photosensitive layer in which an inorganic photoconductor such as ZnO, CdS, or crystalline Se particles is decomposed into an organic binder. Photoreceptors, photoreceptors of these laminated types, organic photoreceptors such as polyvinylcarbazole/2,4.7-trinitro-9-fluorenone (Pv/TNF), and charge transport layers using copper phthalocyanine as a charge generation layer. It is possible to produce a laminated type photoreceptor in which the following layers are laminated.

As the protective layer, a material obtained by adding a conductivity control agent such as an organic compound or an inorganic compound to an organic polymer compound is used. Organic compounds include metallocene compounds, and inorganic compounds include gold, silver, copper, nickel, and aluminum powders, zinc oxide, titanium oxide, tin oxide, indium oxide, and antimony oxide, containing tin oxide, and aluminum oxide. Examples include indium-containing tin oxide.

Next, examples and comparative examples will be described.

Example 1 A photosensitive layer was formed by depositing an AS2Set film to a thickness of 60 μm on an A1 plate. When this was positively charged and exposed to light using an electrophotographic property evaluation machine (manufactured by Kawaguchi Electric, model 5P-428 evaluation machine), the charging potential was 1028V, and the potential after 20 seconds in the dark was 240V.

On this photosensitive layer, a mixture of 10 parts by weight of methylsilyl isocyanate, 10 parts by weight of tetrasilylisocyanate and 80 parts by weight of butyl acetate was applied by dipping and coating at 25°C and 60 parts by weight.
%RH for 2 hours, and an intermediate layer of about 200 OA was applied.1. Furthermore, on top of this, polyester resin (V-200,
A dispersion obtained by dispersing 10 parts by weight of tin oxide powder (containing iowt% of antimony oxide, manufactured by Mitsubishi Metals) and 90 parts by weight of dichloroethane in a ball mill for 48 hours was coated and dried to form a 5μ protective layer. was used as a photoreceptor.

This photoreceptor has a charging potential of 1832V, and a potential of 1 after 20 seconds in the dark.
The voltage was 132V, indicating high charge retention characteristics.

The sensitivity is 1.6 as the exposure amount from 800V to 80V.
0 1x-sec, showing high sensitivity, and the residual potential is 2
It was 0V.

Example 2 After obtaining a photosensitive layer in the same manner as in Example 1, a mixture of 7 parts by weight of vinylsilyl isocyanate, 10 parts by weight of tetrasilyl isocyanate, and 83 parts by weight of butyl acetate was applied onto the photosensitive layer by immersion, and the mixture was heated at 25°C. , dried at 60% RH for 2 hours.
A photoreceptor similar to Example 1 was obtained except that an intermediate layer of 50 OA was provided.

The charging potential of this photoreceptor was also 1500 V, and the band NN level was 980 V after 20 seconds of darkness. The sensitivity from aoov to 80■ was 1.081x-sec, and the residual potential was 12V, showing excellent characteristics.

Example 3 A 60μ thick AS2S03 vapor deposited film was formed on an AI cylinder. On top of this, an intermediate layer similar to that in Example 1 was provided. Styrene-methacrylic acid-acrylic acid-N-
Methylol acrylamide resin liquid (solid content 4C) wt%
> 40 parts by weight of tin oxide powder containing 10 wt% of antimony oxide and an appropriate amount of solvent were added and dispersed in a ball mill for 72 hours.The dispersion was applied by dip coating at 120°C for 30 hours.
After drying for a few minutes, a protective layer of about 5 μm was formed. When 300,000 copies were continuously copied using this photoreceptor, clear copies were always obtained without peeling of the protective layer and without image abnormalities due to scratches or the like.

Comparative Example A photoreceptor was obtained in the same manner as in Example 1 except that the intermediate layer was not provided. This electrostatic property has a charging potential of 18.6
V, and was hardly charged and no substantial sensitivity could be obtained.

Example 4 60 on A1 drum of 340 x 80φ x 3t (unit: mm)
On a photoreceptor on which As2Se2 is vacuum-deposited to a thickness of μm,
A mixture of two isocyanates with a volume resistivity ρ of 8 x 1012 Ω・cm (10 weights and 1 part of each of tetraisocyanate silane and vinylsilyltriisocyanate [.
uQ) dissolved in 480 parts by weight at a pulling speed of 6 mm/Se
After forming a film at C and drying at 100°C for 2 hours, approximately 120OA
An intermediate layer was prepared.

2 parts by weight of ester-crosslinked styrene-MMA resin, 14 parts by weight of toluene, and 3 parts by weight of SnO2 fine powder with an average particle size of 0.1 μm were mixed into the photoreceptor thus obtained, and the mixture was mixed in a ball mill for 120 hours. Pulling up the dispersion liquid at a speed of 6 m
1II/SeC and dried at 120° C. for 30 minutes to form a protective layer of about 5 μm.

Example 5 Volume resistance ρ is 1×1013Ω on the same photoconductor as in Example 4.
・cm mixture of two types of incyanate (tetraisocyanate silane and methylsilyltriisocyanate 810
(part by weight dissolved in 180 parts by weight of n-BuOl) was formed into a film at a pulling rate of 6 ml/Sec, and after drying at 100° C. for 2 hours, an intermediate layer of approximately 9130 K was created. The following procedure was carried out in the same manner as in Example 4.

Example 6 The same photoconductor as in Example 4 had a volume resistivity ρ of 6 after drying and curing.
．． A mixed solution of silicone resins 440 and 441 (manufactured by Tsukuri Resilicone) dissolved in riboin at a ratio of 4:6 to form a film at a pulling speed of 6 mm/Sec, and dried at 120°C for 1 hour (multiple , 1300 A. The following procedure was carried out in the same manner as in Example 4.

Example 7 The ratio of the two types of silicone resins in Example 6 was 5:5.
The same procedure as in Example 6 was carried out except that.

Example 8 The ratio of the two types of silicone resins in Example 6 was 1=9
The same procedure as in Example 6 was carried out except that.

Example 9 The ratio of the two types of silicone resins in Example 6 was 8:2.
The same procedure as in Example 6 was carried out except that.

Example 10 The same photoconductor as in Example 4 had a volume resistance ρ of 7 after drying and curing.
A film was formed using a dipping method at a pulling rate of 5 mm/SeC in a solution of polycarbonate resin (manufactured by Tijin Kasei, the solvent was a mixed layer of 2 dichloroethane and 8 dichloromethane) with a diameter of It was dried for a minute to form an intermediate layer of 1300 A. Note that overcoating the photoreceptor with a protective layer was discontinued due to the poor solvent resistance of polycarbonate.

Example 11 The same photoconductor as in Example 4 with a volume resistance ρ of 3×1013Ω−
cm a-si N: H layer about 1200! A film was formed. The film forming conditions in the plasma CVD apparatus are as follows.

Rotation speed 1Or, p, III Support temperature 150℃ Back pressure lx 10-' Torr Reaction gas pressure
0.20 Discharge power 200W Flow rate ratio (SCCM) S i H4/H2:N2 =1(100):3(60
) The following procedure was carried out in the same manner as in Example 4.

Example 12 The ratio of SiH4/H2:N2 was set to 1 (10 ()): 5 (
The procedure was the same as in Example 11 except that the temperature was changed to 100).

The test results for Examples 4 to 12 below are summarized in Table 1. Further, the voltage-current characteristics of Examples 6, 7, 8 and 10 are shown in FIG.

[Effects] The present invention is a highly durable photoreceptor with a long mechanical life, and also has excellent characteristics such as low residual potential and no increase in residual potential due to repeated copying. The image quality is stable because the density decrease is within the practical range and there is no afterimage.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the layer structure of the present invention, and FIG. 2 is a graph showing the voltage-current characteristics in Examples. DESCRIPTION OF SYMBOLS 1...Transparent protective layer, 2...Intermediate layer, 3...Photosensitive layer, 4...Electroconductive support. Patent Applicant Ricoh Co., Ltd. - Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroo Asahi 2B Procedural Wa 11 Official Document (Sponsored) April 13, 1985 Commissioner of the Japan Patent Office Kuro 1) Mr. Akio 1, Indication of the incident Patent Application No. 1986-53947 No. 2
, Title of the invention Electrophotographic photoreceptor 3, Person making the amendment (, -, -:""T Relationship to the case Patent applicant
・、、、、l:!・-,', 1 person Ya (674) Ricoh Co., Ltd.
j, , Ni-'J4, Agent 5, Date of amendment order (voluntary) 6. Columns for the specification to be amended, claims, and detailed explanation of the invention (attachment) ■. The scope of the claims on page 1, line 4 and following of the specification is amended as follows. ``2. Claims (1) An electronic harp or true photoreceptor in which a photosensitive layer, an intermediate layer, and a Vi retaining layer are sequentially laminated on a conductive support, wherein the intermediate layer is made of a silyl isocyanate-based material, an alkoxy group-containing silicone resin, an organic An electrophotographic photoreceptor characterized by being at least one of an inorganic material such as a metal complex, a mixture of an organometallic complex and a silane coupling, or a silicon compound or a boron compound. (2) The intermediate layer has the following characteristics. The electrophotographic photoreceptor according to claim (1) has a volume resistivity value ρ of 1Q12Ω·cm≦ρ<104.
Ω・cm, ■ The ratio of forward current (J) per unit volume to the applied electric field (E) of the photoreceptor is 10-'' (A/V-am) > J/E tear, ■
The forward-to-reverse current ratio II/I2 satisfies l/I2≦1. ” ■, “≦f” on page 5, line 15 is corrected to “≦ρ”. ■, "1 rib-in" on page 15, line 14 is corrected to "li-groin." IV, page 16, number 9? -r(7) [1011or 1
0” J Correct.

Claims (2)

[Claims] (1) In an electrophotographic photoreceptor in which a photosensitive layer, an intermediate layer, and a protective layer are sequentially laminated on a conductive support, the intermediate layer is made of a silyl isocyanate-based material, an alkoxy group-containing silicone resin,
An electrophotographic photoreceptor comprising at least one of an organometallic complex, a mixture of an organometallic complex and a silane coupling, or an inorganic material such as a silicon compound or a boron compound. (2) The electrophotographic photoreceptor according to claim (1), wherein the intermediate layer has the following characteristics. [1] Volume specific resistance value ρ is 10^1^2Ω・cm≦f<
10^1^4 Ω・cm, [2] The ratio of forward current (J) per unit volume to the applied electric field (E) of the photoreceptor is 10^-^1^3 (A/V・cm)>J /E, and [
3] Forward to reverse current ratio I_1/I_2 is I_1/
I_2≦1.