JP2833222B2 - Electrophotographic photoreceptor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photoreceptor, and more particularly, to a photoconductive layer formed on a conductive support by including at least two kinds of charge transfer agents in the photoconductive layer. And an electrophotographic photoreceptor having excellent light sensitivity and durability.

[0002]

BACKGROUND OF THE INVENTION Electrophotography, as already disclosed by Carlson in U.S. Pat. No. 2,297,691, is a subtle combination of electrostatic and photoconductive phenomena. After uniformly charging the surface by corona discharge in a dark place, the photo image is converted into an electrostatic latent image using photoconductivity, and a colored charged powder (toner) is adhered to this. This is one of the image forming methods for converting into a visual image.

[0003] The basic electrical and photoelectric properties required of a photoreceptor in such an electrophotographic method include that it can be charged to an appropriate potential in a dark place, that this potential can be maintained for an appropriate time, and that Charges can be quickly dissipated by irradiation.

In such photoreceptors, inorganic photoconductive substances such as amorphous selenium, cadmium sulfide, and zinc oxide have been widely used. These inorganic materials satisfy the above conditions, but also have some disadvantages. For example, cadmium sulfide or zinc oxide is used as a photoreceptor by dispersing it in a resin as a binder, but as it is, it has mechanical defects such as smoothness, flexibility, hardness, tensile strength, and friction resistance. Cannot withstand repeated use. In addition, cadmium sulfide needs to be considered in terms of hygiene.

[0005] Amorphous selenium must be manufactured by vapor deposition, which not only increases the manufacturing cost but also makes it inflexible and difficult to process into a belt. It has drawbacks in that it is sensitive to toxicity, heat and mechanical shock, and requires careful handling.

In recent years, in order to eliminate these disadvantages of the inorganic photoreceptor, research on organic photoreceptors has progressed, and in organic photoreceptors, easiness of film formation, ease of manufacturing, light weight, flexibility, and spectral performance have been improved. Because of the many advantages of multivariability in sensitivity, various organic photoreceptors have been proposed and some have been put to practical use.

For example, poly-N-vinyl carbazole and
Photoreceptor comprising 2,4,7-trinitrofluoren-9-one (U.S. Pat. No. 3,484,237), sensitized with poly-N-vinylcarbazole and a pyrylium salt dye (Japanese Patent Publication No. 48-2)
No. 5658), and a photoreceptor having a eutectic complex comprising a dye and a resin as a main component (JP-A-47-10735).

Further, an electrophotographic photoreceptor has been proposed in which a substance that generates charges by light (called a charge generating agent) and a substance that can move the generated charges (called a charge transfer agent) are combined. Have been. For example, U.S. Pat. No. 3,791,826 discloses a photoreceptor having a charge transfer layer provided on a charge generation layer, and U.S. Pat.No. 3,764,315 discloses a photoreceptor in which a charge generation agent is dispersed in a charge transfer agent. A photoreceptor having a layer is described. By generating and transferring the charge of this kind, the functions of the charge transfer agent and the charge transfer agent are shared by different substances. Is done.

[0009] So far, many useful charge generating agents for this type of photoreceptor have been known. On the other hand, various substances have been proposed as charge transfer agents, but at present it is not always satisfactory. An excellent charge transfer agent is a basic property that, when charged,
That the potential can be sufficiently maintained, that light having an effective wavelength such that charges are generated from the charge generating agent is sufficiently transmitted to the charge generating agent, and that the charges generated by the charge generating agent are quickly moved. It has the ability. In addition, the characteristics required for practical use include being able to form a uniform film by itself or dissolved in a binder, under severe environmental conditions such as temperature, humidity and ozone and NOx generated during corona discharge. In this case, it is necessary not to bring about deterioration or change of the electrostatic characteristics. Heretofore, polyphenyl compounds such as triphenyl can be classified by chemical structural formula as this type of charge transfer agent, U.S. Patent No. 3,717,462,
Hydrazone compounds described in U.S. Patent No. 4,150,987 and JP-A-55-52064; U.S. Patent No. 3,820,989
Diarylalkane compounds described in the specification,
2,5-bis (P-diethylaminophenyl) -1,3,4-oxadiazole described in U.S. Pat. No. 3,189,477, a pyrazoline compound described in U.S. Pat. It is a relatively excellent charge transfer agent proposed in recent years. However, at present, these charge transfer agents cannot be said to satisfy all of the above conditions.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrophotographic photosensitive member having excellent sensitivity, repetition characteristics, durability and the like.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a method of forming a conductive support on a conductive support.
Using a charge generating agent and a charge transfer agent
In the photoconductor, the value of a in the following formula 1 at room temperature is small.
Contains at least 0.32 different charge transfer agents
And an electrophotographic photosensitive member. log μ = a × log E + b (Formula 1) (In the formula, μ represents the mobility (cm ² / V · sec) of the charge transfer agent, E represents an electric field (V / cm), and a and b represent real numbers. )) Also, the present invention
Has a charge generation agent containing a charge generation agent on a conductive support.
Layer and a charge transfer layer containing a charge transfer agent.
The electron, wherein the thickness of the charge transfer layer is 100 μm or less.
It relates to a photoreceptor. Further, according to the present invention, when the value of a in Equation 1 is
The charge transfer agent having a value of 0.5 or less and the value of a is 0.5 <a <
Each containing at least one kind of charge transfer agent in the range of 1.0
The present invention relates to the above electrophotographic photoreceptor. Ma
Further, the present invention provides a charge transfer agent wherein the value of a in Formula 1 is 0.5 or less.
And each of the charge transfer agents having a value of 1.0 or more
The above electrophotographic photoreceptor characterized by containing the above
Related. Further, according to the present invention, the value of a in Equation 1 is 0.5 <a <
A charge transfer agent of 1.0 and a charge transfer
Characterized in that it contains at least one of each of the kinetic agents
The present invention relates to the electrophotographic photosensitive member.

An object of the present invention is to provide an electrophotographic photosensitive member having high sensitivity and low residual potential by containing two or more kinds of charge transfer agents having different electric field dependences of mobility. Another object of the present invention is that when used as a photoreceptor for repetitive transfer electrophotography in which charging, exposure, development, and transfer steps are repeatedly performed, the deterioration of charging characteristics due to fatigue and memory phenomenon due to repeated use is small. Another object of the present invention is to provide an electrophotographic photoreceptor having excellent durability and environmental properties that maintains stable characteristics under various severe environments at low to high temperatures and low to high humidity.

In the present invention, a in Equation 1 can be obtained by a general method such as a time-of-flight method. In the present invention, the form of the electric field dependence of the mobility is obtained by the Sher-Montroll theory as described in, for example, Physical Review Magazine B12, p. The value of a in Equation 1 is
It is expressed as the slope when the electric field and mobility are log-log plotted and approximated as a straight line. For this approximation, first-order regression by the method of least squares is generally used. In general, the electric field dependency tends to largely deviate from this straight line due to various factors on the low electric field side.
A linear approximation was performed in a range from 0 to the fourth power to 1 × 10 to the fifth power (V / cm).

Table 1 shows typical examples of the charge transfer agent used in the present invention and the value of a in the formula (Formula 1) of each charge transfer agent.

[Table 1] The photoreceptor of the present invention is provided on a conductive support in the same layer as the charge transfer agent and the charge generating agent of the present invention, and is usually referred to as a single-layer type photoreceptor, or mainly includes a charge generating agent. It can be used in a configuration generally called a laminated photoconductor, which is formed by forming two layers of a first layer containing a charge transfer agent and a second layer mainly containing a charge transfer agent on a conductive support. . The selection of these structures is appropriately selected depending on the polarity used by the photoreceptor. Further, examples of the charge generating agent used in the present invention include the following. Selenium, selenium alloy, CdS, ZnO, C
An inorganic optical semiconductor such as dSe or amorphous silicon can also be used, but it is preferable to use an organic charge generating substance. Examples of organic charge generating agents include, for example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azo dyes such as monoazo dyes and disazo dyes, indigo pigments, quinacridone pigments, indanthrene pigments, xanthene dyes, benzimidazole Dyes and pigments such as pigments, perylene pigments, squaric menane dyes, or eutectic complexes formed from a pyrylium salt dye and a polycarbonate resin, charge transfer complexes comprising an electron-donating substance such as polyvinylcarbazole and an electron-accepting substance such as TNF And the like, but it is particularly preferable to use a phthalocyanine pigment.

Since the charge transfer agent in the present invention does not have a film forming ability by itself, a binder resin is used to form a photosensitive layer. Also, as for the charge generating agent, since a film cannot be formed by itself except for a polymer resin such as polyvinyl carbazole, a binder may be used if necessary.

The binder preferably used in the present invention is a high electric insulating film-forming polymer or copolymer. Such high-molecular polymers, copolymers, binders preferably used in the present invention, phenol resin, polyester resin, vinyl acetate resin, polycarbonate resin, polypeptide resin, cellulose resin, polyurethane resin, polyvinylpyrrolidone ,
Polyethylene oxide, polyvinyl chloride resin, starch, polyvinyl alcohol, acrylic copolymer resin, methacrylic copolymer resin, silicone resin, polyacrylonitrile copolymer resin, polyacrylamide, polyvinyl butyral, polyvinyl carbazole, polyvinylidene chloride resin And the like. These binders
Used alone or in combination of two or more,
The binder that can be used is not limited to these. Further, the photoreceptor of the present invention is provided with a charge generation layer containing a charge generation agent as a main component via an intermediate layer as needed on a conductive support, and containing a charge transfer agent as a main component adjacent to the layer. A stacked structure including a charge transfer layer may be employed. In the case of such a laminated structure, which one of the charge generation layer and the charge transfer layer is formed as the upper layer is determined by whether the chargeability is positive or negative. Generally, in the case of negative charging, it is advantageous in terms of characteristics to make the charge transfer an upper layer. In the photoreceptor of the present invention, when the charge generating layer and the charge transfer layer each have a laminated structure including separate layers, the charge generating layer may be directly on the conductive support or, if necessary, an adhesive layer or a barrier. Either vacuum deposition on the intermediate layer such as a layer, or applying a solution in which a charge generating agent is dissolved in an appropriate solvent, or a ball mill, an attritor, etc. If necessary, it can be provided by a method such as applying a dispersion obtained by mixing and dispersing with a binder . The binder used at this time may be the same as that used for the charge transfer layer.

Further, the photosensitive layer of the present invention may be a single photosensitive layer comprising a charge transfer agent and a binder.

The charge transfer layer preferably contains 10 to 300 parts by weight of the charge transfer agent per 100 parts by weight of the binder. However, the present invention is not limited only to this range. The thickness of the photosensitive layer is determined by the required photosensitivity and durability, and the mixing ratio of the charge generating agent and the charge transport agent to the binder. The thickness of the photosensitive layer on the conductive support is 5
0 μm or less, preferably 7 to 30 μm, is also suitable in view of the flexibility of the coating.

The photosensitive layer may be coated with a layer serving as a protective layer, if necessary.

The charge generation layer and the charge transfer layer of the electrophotographic photoreceptor of the present invention may contain a known sensitizer.
Also, if necessary, surfactants, plasticizers, antioxidants,
UV absorbers, dispersing aids, anti-settling agents, and the like can be used as appropriate.

[0021] As the support used in the electrophotographic photoreceptor of the present invention, if it is conductive grant may be of any, no problem even in any of the type of the conductive layer used conventionally. Specifically, aluminum, copper,
Metals such as stainless steel and brass, plastics on which aluminum, indium oxide, tin oxide, and the like are deposited or laminated, or conductive particles such as carbon black, tin particles, and plastics in which aluminum particles are dispersed can be given. The shape may be a sheet shape, a cylinder shape, or other shapes. When the electrophotographic photoreceptor according to the present invention is used, the light source is usually a halogen lamp or the like, and when the charge generating agent is phthalocyanine, the sensitivity is 750 nm or more. Laser light such as a laser (oscillation wavelength 780 nm) can also be used.

Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples. Hereinafter, in the examples, “parts” in the examples indicates parts by weight.

[0023]

Example 1 At room temperature, on a NESA glass (500Ω manufactured by Furuuchi Chemical), the compound NO. 1 and 5 parts.
A solution prepared by dissolving 5 parts of 3 in 500 parts of chloroform was cast to form a charge transfer layer having a thickness of 10 ± 2 μm. After drying at room temperature for several days, a gold electrode was sputtered on the charge transfer layer to produce a counter electrode.

At 25 ° C., 337 from the NESA glass side
After irradiating pulse light of a nitrogen laser with a pulse width of 5 (nsec) having a wavelength of (nm) and amplifying the TOF signal with a preamplifier (made by yourself), the TOF signal is taken into a transient memory (M100-E manufactured by Kawasaki Electronica K.K.) Computer analysis was performed to determine the transit time.

The mobility was obtained from the following equation (2), and the electric field and the mobility were log-logarithmically plotted to obtain the value of a. μ = L2 / V × t _T (Equation 2) (where L represents the thickness of the charge transfer layer (cm), V represents the applied voltage (V), and t _T represents the transit time (sec).)

Next, on the aluminum surface of a polyethylene terephthalate sheet (75 μm) on which aluminum was vapor-deposited, 3 parts of a τ-type non-metallic phthalocyanine, a vinyl chloride vinyl acetate copolymer resin (trade name VMC manufactured by Union Carbide Co., Ltd.)
H) A coating liquid dispersed in 3 parts with 94 parts of tetrahydrofuran in a ball mill for 2 hours was applied and dried at 100 ° C. for 2 hours to form a 0.25 μm charge generation layer.

Further, compound NO. 1 for 5 parts, NO. A solution prepared by dissolving 5 parts of No. 3 and 10 parts of a polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) in 100 parts of methylene chloride was applied on the charge generation layer, and dried to form a 15 μm charge transfer layer.

The electrophotographic photoreceptor prepared as described above was subjected to -5.4 KV by an electrostatic copying paper tester SP-428 manufactured by Kawaguchi Electric.
, And the white light half-decrease exposure sensitivity (E1 / 2) was determined from the surface potential and the time when the amount of charge was reduced to し て by irradiating white light of 5 lux.

Next, the photosensitive member was affixed to a drum of an electrophotographic copying machine having a corona charger, an exposure section, a transfer charging section, a charge removal exposure section, and a cleaner. The dark part potential of this copying machine was set to -650 V, the light part potential was set to -150 V, and a repetition durability test of 5,000 sheets was performed. The obtained image was evaluated on a 5-point scale based on the following criteria. ◎ ─very good, ○
─good, △ ─ordinary, × ─bad, xx─very bad

[0030] was prepared (Examples 2-4) the photoreceptor by exactly the same method as in Example 1 except that instead of the compounds shown in Table 2 as a charge transfer agent. (Table 2) Example Compound (parts by weight) Compound (parts by weight) ──────────────────────────── 21 (5) 5 (5) 3 2 (8) 4 (2) 4 3 (3) 5 (9) ────────────────────────────

( Comparative Examples 1 to 4 ) Photoconductors were prepared in exactly the same manner as in Example 1, except that the charge transfer agent was changed to one kind of the compound shown in Table 3 and 10 parts. (Comparative Example 5) 5 parts each of the compounds shown in Table 3 as a charge transfer agent
Except for changing to one,
An optical body was made . (Table 3) Comparative Example Compound (parts by weight) Compound (parts by weight) ──────────────────────── 1 1 (10) 2 3 (10) 3 4 (10) 4 5 (10) 5 1 (5) 2 (5) ──────────────────────────────

The results are shown in Table 4. (Table 4) ───────────────────────────── Surface potential Half-exposure exposure sensitivity Residual potential Image (-V) E1 / 2 ( lux · s) (−V) ───────────────────────────── Example 1 705 1.00 ◎ Example 2 735 0.80 ◎ Example 3 700 0.90 ◎ Example 4 715 1.10 ◎ Comparative Example 1 695 2.7 10 × Comparative Example 2 720 1.8 25 △ Comparative Example 3 740 3.1 30 △ Comparative example 4 690 2.4 20 × Comparative example 5 710 1.2 5 ○ ──────────────────────────────

[0033]

According to the present invention, an electrophotographic photosensitive member having high sensitivity, low residual potential and image stability can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-166547 (JP, A) JP-A-3-192368 (JP, A) JP-A-3-231252 (JP, A) JP-A-4- 130434 (JP, A) JP-A-63-223755 (JP, A) JP-A-2-1733653 (JP, A) JP-A-2-198452 (JP, A) JP-A-2-176664 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 5/00-5/16

Claims (5)

(57) [Claims] 1. A electrophotographic photosensitive member formed by using the electrically conductive substrate a charge generating material and a charge transfer agent, bets room temperature
Electrophotographic photoreceptor Kino value of a following equation 1, characterized in that it contains at least 0.32 different two or more charge transfer agents. log μ = a × log E + b (Formula 1) (In the formula, μ represents the mobility (cm ² / V · sec) of the charge transfer agent, E represents an electric field (V / cm), and a and b represent real numbers. .) To 2. A conductive substrate, containing a charge-generating agent
A charge generation layer and a charge transfer layer containing a charge transfer agent.
It was a layer, the electrophotographic photoreceptor of <br/> claim 1, wherein the thickness of the charge transport layer is 100μm or less. 3. The method according to claim 1, wherein at least one of a charge transfer agent having a value of a of 0.5 or less and a charge transfer agent having a value of a of 0.5 <a <1.0 is contained. Claim 1.
Or the electrophotographic photosensitive member according to 2. The value of a according to claim 4 of formula 1 characterized in that the value of 0.5 or less of the charge transfer agent and a contains one or more kinds of 1.0 or more charge transfer agents according to claim 1 or 2. The electrophotographic photosensitive member according to 2. 5. The method according to claim 1, wherein at least one of a charge transfer agent having an a value of 0.5 <a <1.0 and a charge transfer agent having an a value of 1.0 or more is contained. The electrophotographic photoreceptor according to claim 1 or 2, wherein