JPS61103156A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To stabilize acceptance potential and residual potential at the time of repeated uses by using a specified squarinic acid deriv. as a material for an electrostatic charge generating layer. CONSTITUTION:A charge transfer layer, the charge generating layer, and a surface protective layer low in resistance are successively laminated on a conductive substrate and the charge generating layer is formed by dispersing the squarinic acid represented by formula I as the charge generating material, preferably, in an amt. of 20-50wt% into a binder resin, such as polyvinyl butyral or various other resins. A preferable particle diameter of said deriv. is in the range of 0.05-1mum.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrophotographic photoreceptor.

[Prior art]

Conventionally, there have been many configurations of laminated organic photoreceptors in which a charge generation layer is laminated as a lower layer of a charge transport layer.Currently, most of the charge transport layers found generally have hole transport properties. Therefore, it is necessary to use a photoreceptor with such a configuration with a negative charge.Therefore, there are various problems that can impact the photoreceptor, such as the generation of high concentrations of ozone due to negative charging and uneven charging of the corotron. In order to overcome this drawback, the charge generation layer was laminated as an upper layer of the charge transport layer and used with positive charging, and in order to further improve mechanical strength, deterioration, etc., a low resistance layer was used as the top layer. Attempts have been made to construct a structure in which a surface protective layer is laminated. However, photoreceptors with such a structure do not have sufficient charging properties, resulting in low contrast and
Only the potential can be destroyed, or even if the charging property is sufficient, the light attenuation is insufficient and the residual potential is high.Charging level 4, the residual potential fluctuates due to changes in temperature and humidity, Charging level 4 when using a counterattack the residual potential changes,
It had various drawbacks, such as a large decrease in sensitivity if used before applying a surface protective layer.

CObject of the invention] The object of the present invention is to provide an electrophotographic photoreceptor free from such drawbacks,
That is, it is an object of the present invention to provide an electrophotographic photoreceptor that prevents a decrease in charging potential, a high residual potential, the influence of temperature and humidity, and a decrease in sensitivity, and has a stable charging potential and residual potential during repeated use.

[Structure of the invention]

The object of the present invention can be achieved by using a specific squaric acid derivative as a material for the charge generation layer. A further object of the present invention is to provide a low-resistance surface protective layer made of fine particles of a specific conductive metal oxide dispersed in an insulating resin on a charge generation layer using a specific squaric acid derivative. It can be achieved.

,・ The present invention provides a charge “transfer layer” on a conductive support.
An electrophotographic photoreceptor characterized in that a charge generation layer and a low resistance surface protection layer are sequentially laminated, and a squaric acid derivative represented by the following structural formula (1) is dispersed in the charge generation layer. be.

Supports with conductive surfaces used in the present invention include drums and sheets of metals such as aluminum, copper, iron, zinc, nickel, etc.;
Vapor deposition of metals such as platinum, palladium, titanium, nickel-chromium, stainless steel, copper-indium, etc., vapor deposition of conductive metal compounds (e.g. 1n203, S+102), lamination of gold R foil, or carbon black, conductive metal compounds (e.g. , 1n2L, 5b203-3no2, SnO2,
Drum-shaped, sheet-shaped, plate-shaped paper, plastic, glass, etc., whose surfaces are electrically conductive treated by dispersing Ti0x powder, metal powder, etc. in a binder resin and applying the coating, are used.

In the charge transport layer used in the present invention, charge transport materials include pyrene, N-ethylcarbazole, N-isopropylcarbazole, 2,5-bis(P-diethylaminophenyl)-1,3,4-oxadiazole, 1- phenyl-3
-(P-diethylaminostyryl)-5~(P-diethylaminophenyl)pyrazoline, ■-[pyridyl-(2
)]-3-(P-diethylaminostyryl)-5-(P
-diethylaminophenyl)pyrazoline, 1-[quinolyl-(2)] -3-(P-diethylaminostyryl 1
5-(P-diethylaminophenyl)pyrazoline, triphenylamine, N,N'-diphenyl N, N'-bis(3-methylphenyl)-1f:1.1'-biphenyl]-4,4''-diamine, 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, 4,4°-
Bennylidenebis(N,N'-diethyl-m-)luidine, PoIJ-N-vinylcarbazole, Hao If
-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylpyreneshinho IJ -9-vinylphenylanthracene, pyrene-
Examples include formaldehyde resin, ethylcarbazole-formaldehyde resin, and the like.

These charge transport materials can be used alone or in combination of two or more. Charge transport materials are not limited to those described here. Binder resins used in the charge transport layer include acrylic resin, methacrylic resin, polystyrene, polyester, polyacrylate,
General-purpose resins such as Poly°Sal 7-on, polycarbonate,
Hole transporting polymers such as po'J N-vinylcarbazole can be used. In addition, the conductive support and
An adhesive layer may be provided between the charge transport layers.

The charge generation layer used in the present invention uses the above-mentioned squaric acid derivative as a charge generation material, and adds this to a binder resin, for example, from 5% to 90% by weight, preferably 20% by weight.
50% by weight was dispersed from Particles of squaric acid derivative (0.02 pm to 3 μm for fleas,
Preferably, 0.05 μm to 1 μm is appropriate. Examples of the binder resin for the charge generation layer include polyvinyl butyral, polyvinyl acetate, polyester, polycarbonate, phenoxy resin, acrylic resin, polyacrylamide, polyamide, polyvinylpyridine resin, casein, polyvinyl alcohol, and polyIJ-N-vinylcarbazole. Various resins are used.

The low-resistance surface protective layer used in the present invention is a layer in which fine particles of a conductive metal oxide are dispersed in an insulating resin, and the electrical resistance of the conductive metal oxide is 10! ' An average size of 9 cm or less and exhibiting a white, gray or blue-white color with a diameter of 0.
Fine particles of 3 μm or less, preferably 0.1 μm or less are suitable, and include single substances such as antimony oxide, tin oxide, titanium oxide, indium oxide, solid solutions of tin oxide and antimony or antimony oxide, or mixtures thereof, or single particles. - Examples include particles in which these metal oxides are mixed or coated. Among them, tin oxide and antimony (or antimony oxide), 1.
A solid solution with or tin oxide is preferably used because it can lower the electrical resistance and make the protective layer substantially transparent (Japanese Patent Laid-Open No. 57-30847,
(Refer to Japanese Patent Application Laid-Open No. 57-12834/1).

The protective layer is desirably constructed so that its electrical resistance is [0' to IO+4 Ω·cm. Electrical resistance is 1014Ω・
If it is more than 109 Ω·IJ, the residual potential will increase, resulting in a copy with a lot of fog, and if it is less than 109 Ω·IJ, the image will be blurred and the resolution will be lowered. The protective layer must also be constructed so as not to substantially block the passage of light used for imagewise exposure.

If the particle size of the conductive metal oxide used is too large, the protective layer becomes opaque, resulting in desensitization and a decrease in image density.

The particle size is determined by the wavelength of light used for image exposure (0.42-0.
It is desirable to use particles having a particle size of 8 μm or less, preferably one half or less, that is, 0.3 μm or less, preferably 0.1 μm or less.

As the insulating resin, it is desirable to use an electrically insulating transparent resin whose electrical resistance is unlikely to change due to changes in humidity or temperature. Insulating materials include condensation resins such as polyamide, polyurethane, polyester, epoxy resin, polyketone, and polycarbonate, and vinyl polymers such as polyvinyl ketone, polystyrene, and polyacrylamide, among which polyurethane has the highest film strength. , is preferably used in terms of chemical stability.

The fine particles of conductive metal oxide are 20% of the insulating resin.
Preferably, the dispersion ranges from % to 60% by weight. 20
If it is less than 60% by weight, the electrical resistance will be 10'4 Ω·cm or more, and if it is more than 60% by weight, the film strength of the protective layer will be significantly reduced. Therefore, the dispersion is preferably carried out in a range of 30% by weight to 50% by weight.

Further, a charge injection blocking auxiliary layer may be further provided between the low resistance surface protection shaft and the charge generation layer. Examples of the auxiliary layer forming material include coupling agents such as silane coupling agents and titanium coupling agents, organometallic compounds such as organic zirconium compounds and organic titanium compounds, and general-purpose resins such as polyester and polyvinyl butyral.

The thickness of each layer is suitably 5 μm to 40 μm for the charge transport layer, preferably 8 μm to 30 μm, 5 μm or less for the charge/q generation layer, preferably 0.1 μm to 3 μm, and 0.5 μm for the low resistance surface protection layer. ~20μm, preferably 1μm-
10 μm is appropriate.

〔Example〕

Examples of the present invention are shown below.

Example 1 A photoreceptor was prepared by sequentially laminating a charge transport layer, a charge generation layer, and a surface protection layer made of the following materials on an aluminum substrate.

Charge transport layer Polycarbonate resin 60 weight BVx (
2()μ) (Teijin: Panline) 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone 4
0 parts by weight Charge generation layer Squaric acid derivative (1μ) (Structural formula ([)) 25 parts by weight 88 Surface protective layer Tin oxide powder 40 parts by weight (1μ)
60 parts by weight of polyurethane resin This photoconductor was positively charged by discharging +6 kV (D-) using a commercially available electrostatic copying paper testing device (Kawaguchi Electric: Electrostatic Paper Analyzer 5P-428).
Measure the surface potential VDDP after leaving it in the dark for 1 second,
Immediately after that, irradiate 5 lux tungsten light for 3 seconds, and ■89. The amount of light 41E'A required to reduce the amount by half was determined.

Furthermore, after this, 200 lux light was irradiated for 0.5 seconds to further attenuate the surface potential, and the residual potential RP was determined.

This measurement is performed 1000 times in succession, and the difference between Vn and pSRP between the 1st cycle and the 1000th cycle is calculated as ΔVoop.
(C), cycle stability was expressed as ΔRP (C).

In addition, similar measurements were carried out at 10°C and 20% RH and at 30°C.
Performed in an environment of 80% RH, 1st cycle and 100%
■ at the 0th cycle. ,,, the difference in RP is △vo,, (
Environmental stability was expressed as E) and ΔRP(E).

Each measured value in this example is shown below.

Voop: 1220V E'A: 1.5 Lux・sec RP Near 0V ΔV,,,, (C): 120V ΔRP(
C): 20V ΔV, p(E): 60V Δ
RP (E): 30V, it can be said that it has sufficient chargeability, high sensitivity, excellent cycle stability, and environmental safety.

Comparative Example 1 Example 1 except that β-type copper phthalocyanine was used instead of the squaric acid derivative in the charge generation layer in Example 1.
A photoreceptor was prepared in the same manner as above, and the same measurements were performed, and the following values were obtained.

Vnop near 00V E each: 8.0 Lux・sec RP: 80V ΔVoop (C): 250V ΔRP(C)
: 30V Δvoop (E) : 250V ΔR
P (E): 40V charging property is low and cycle,
This indicates that there is a problem with the bipartite quality of the requirements.

Comparative Example 2 A photoreceptor was prepared in the same manner as in Example 1 except that 2μ of methyl cellulose was used instead of the surface protective layer in Example 1, and the same measurements were performed, and the following characteristics were shown.

Voop: 100OV E'A1. olux・sec RP: 110V ΔVoop (C): 150V ΔRP(C)
: 40VΔVoop (E) : 300V ΔR
P (E): 100V It can be seen that there is a problem with environmental stability in particular.

Examples 2 to 5 Photoreceptors were prepared and measured in the same manner as in Example 1, except that the binders in the charge transport layer and charge generation layer in Example 2 were changed to the following combinations. It showed sufficient chargeability, high sensitivity, and excellent stability.

Example 6 A photoreceptor was prepared and measured in the same manner as in Example 1, except that the surface protective layer in Example 1 was changed to tin oxide-antimony oxide solid solution/polyurethane resin-40/60 (parts by weight). It exhibited stable characteristics similar to those of the photoreceptor of Example 1.

vo,,: 1150V E'A: l, 4 lux・sec RP: 60V Δ■,. p([:):100V ΔRP(C):3
0VΔVonp(E): 80VΔRP(E
): 15V [Effects of the Invention] According to the present invention, an electrophotographic photoreceptor having excellent chargeability, sensitivity, cycle stability, and environmental stability can be obtained.

[Brief explanation of drawings]

′! 51 to 4 are sectional views of specific examples of the electrophotographic photoreceptor of the present invention. 10...Low resistance surface protective layer, 11...
Electrographic generation layer, 12...Charge transport layer, 13...
... Conductive support, 14 ... Conductive metal oxide, 15 ... Charge generating material, 20 ...
Adhesive layer, 30...Charge injection blocking auxiliary layer.

Claims (2)

[Claims] (1) A charge transport layer, a charge generation layer, and a low resistance surface protection layer are sequentially laminated on a conductive support, and the charge generation layer contains the following structural formula (I) ▲Mathematical formula, chemical formula, table, etc.▼(I ) An electrophotographic photoreceptor characterized by dispersing a squaric acid derivative represented by: (2) The low-resistance surface protective layer consists of a layer in which fine particles of a conductive metal oxide are dispersed in an insulating resin, and the conductive metal oxide has an electrical resistance of 10^9 Ω·cm or less and an average particle size. 0
．． The electrophotographic photoreceptor according to claim (1), characterized in that the particles are 3 μm or less.