JPS60250357A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain an electrophotographic sensitive body having excellent durability, etc. by using the materials formed by melting Se raw materials contg. Te and halogen at respectively different ratios at a specific temp. then holding the melts for specified time or above at the temp. lower than the melting temp. and cooling quickly the melts to solidify to form a carrier transfer layer and carrier generating layer and laminating said layers. CONSTITUTION:The material formed by melting the Se raw material contg. <12wt% Te and contg. halogen at 370-430 deg.C then holding the melt for >=30min and within about 120min at 240-360 deg.C lower than the melting temp. and cooling quickly the melt to an ordinary temp. to solidify by charging the melt into water or the like is deposited by evaporation on a conductive base 1 to form the carrier transfer layer 3. The Se raw material formed by melting the Se raw material contg. 12-35wt% Te and contg. halogen at the ratio lower than the ratio thereof in the material for the layer 3 at 380-450 deg.C then holding the melt for 30-180min at 250-420 deg.C lower than the melting temp. and cooling quickly the melt to solidify is deposited by evaporation on the layer 3 to form the carrier generating layer 2. The electrophotographic sensitive body formed with the laminated photosensitive layer 4 having high photosensitivity, excellent durability, etc. is thus obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor comprising a conductive support and a photosensitive layer comprising a combination of a carrier generation layer and a carrier transport layer. be.

[Prior art]

To date, carrier-generating substances (hereinafter simply referred to as "carriers") that absorb visible light and generate charge carriers (hereinafter simply referred to as "carriers") have been developed.
Hereinafter also referred to as rCGMJ. ) (hereinafter also referred to as r CGL J), and this CGL
A carrier transport layer (hereinafter referred to as rcTL) containing a carrier transport material (hereinafter also referred to as rCTMJ) that transports either or both of positive and negative carriers generated in
It has been proposed that the photosensitive layer of an electrophotographic photoreceptor is formed by combining the photoreceptor (also referred to as J). In this way, by assigning the two basic functions necessary for a photosensitive layer, namely carrier generation and carrier transport, to separate layers, the range of materials that can be used in the composition of the photosensitive layer is widened, and It becomes possible to independently select materials or material systems that optimally perform each function, and by doing so, it is possible to achieve the characteristics required in the electrophotographic process, such as high surface potential when charged and charge retention. It becomes possible to construct an electrophotographic photoreceptor having excellent properties such as a large amount of light, high photosensitivity, and high stability in repeated use.

Conventionally, such a photosensitive layer is made of selenium or a selenium alloy containing selenium as a main component, so-called selenium-based C.
Laminated layers of GL and selenium-based CTI have been widely put into practical use. In order to particularly increase the spectral sensitivity in the visible region, it is effective to add tellurium, which is less toxic than arsenic, to selenium, and when the tellurium content is 12 to 35% by weight, photoconductivity It has high characteristics and is useful as a CGL from this point of view.On the other hand, when the tellurium content is less than 12% by weight, it has the characteristics of low dark decay and high charge retention, and from this point of view. C
Useful as TL. And selenium-based CG like this
When a trace amount of halogen is contained in L- and selenium-based CTL, even higher photoconductivity can be obtained, and this halogen-containing effect is particularly noticeable when the halogen content of CTL is larger than that of CGL. , a CGL like this
A photosensitive layer formed by combining CTL and CTL is desirable because it has a small residual potential even when repeatedly subjected to an electrophotographic process.

However, in such an electrophotographic photoreceptor having a selenium-based photosensitive layer, the photosensitive layer has low high-temperature durability, and therefore deteriorates quickly in a high-temperature atmosphere and loses its excellent properties at an early stage. There is a drawback.

An electrophotographic photoreceptor having a selenium-based photosensitive layer is usually manufactured by using a selenium substance of a desired composition as an evaporation source and depositing the selenium substance on the surface of a conductive support made of a metal drum such as aluminum. . The selenium substance used as the evaporation source is usually manufactured by a method that includes a step of once melting the raw material, but the conditions for manufacturing this selenium substance are such that the photosensitive layer of the electrophotographic photoreceptor that is finally formed This has a considerable influence on the characteristics.

[Purpose of the invention]

The present invention was completed as a result of various studies focusing on the above circumstances, and its purpose is to provide a photosensitive layer comprising a combination of a selenium-based carrier generation layer and a selenium-based carrier transport layer. It is an object of the present invention to provide an electrophotographic photoreceptor that has the following properties, is capable of reliably suppressing crystallization even at high temperatures, and can stably obtain excellent photosensitive characteristics over a long period of time.

[Structure of the invention]

The above object is to provide an electrophotographic photoreceptor in which a photosensitive layer comprising a combination of a carrier generation layer and a carrier transport layer is provided on a conductive support, in which the carrier transport layer contains a selenium raw material at 370 to 430°C.
A first material having a tellurium content of less than 12% by weight and containing halogen, obtained by heating and melting at a temperature within the range of The carrier generation layer is made of a photoreceptor material of 380 to 450"C
The first photosensitive material containing 12 to 35% by weight of tellurium obtained by heating and melting at a temperature within the range of , then holding at a temperature lower than the heating temperature for a certain period of time or more, and then cooling and solidifying. This is achieved by an electrophotographic photoreceptor characterized in that it is formed from a second photoreceptor material that contains (or does not contain) a smaller proportion of halogen than the body material.

The present invention will be explained in detail below.

In the present invention, a CTL is formed by using a first photoconductor material containing halogen and having a tellurium content of less than 12 weight by weight, which is produced by a method described in detail below, as a CTI material, A second photoreceptor material containing 12 to 35% by weight of tellurium and containing or not containing a smaller proportion of halogen than the first photoreceptor material, the details of which are manufactured by a method described later. A CGL is formed using CGL as a CGL material, and by combining these CGL and CTL, a photosensitive layer of a so-called functionally separated photoreceptor is constructed in which generation and transport of carriers are performed using separate substances.

The first photoreceptor material containing less than 12% by weight of tellurium and containing halogen and used as a CTL material in the present invention is produced as follows.

That is, selenium, tellurium, selenium halides and/or
Alternatively, a selenium raw material is prepared by adding a tellurium halide in a required ratio. This selenium i jF4 wom
The selenium, tellurium, selenium halide, and tellurium halide that make up the composition may be in any of various forms such as crushed ingots, granules, and powders, but from the viewpoint of being easily meltable, Granules or powders are preferred, and the particle size is, for example, 0.5 in diameter.
~5 dragons are desirable. The halogen elements forming selenium halides or tellurium halides include fluorine, chlorine, bromine, and iodine, and two or more types of halides may be contained in the selenium raw material.

Such a selenium raw material is heated and melted. For example, a selenium raw material is placed in a crucible and placed in a vacuum atmosphere or an inert gas atmosphere such as helium, argon, or nitrogen.
Using an electric oven or the like, the temperature is rapidly or stepwise raised from room temperature to a temperature in the range of 370 to 430°C to melt it by heating, and the melt is heated at a constant temperature of 30 to 240°C. Preferably 60 to 180 minutes
The selenium raw material is continuously stirred using a screw stirrer or the like for several minutes to sufficiently homogenize the composition of the melt. The heating temperature for melting the selenium raw material is a temperature at which the selenium raw material melts and the melting point of tellurium (45
0℃) or lower, and the range is 370 to 430℃
shall be. If this heating temperature exceeds 430°C,
Among the CTLs formed from the obtained first photoreceptor material, there may be some that tend to crystallize at high temperatures, and crystallization suppression at high temperatures is not reliable. The heating temperature can be lowered as the tellurium content is lower, but if it is lower than 370°C, melting will be insufficient and tellurium will segregate in the resulting first photoreceptor material. Therefore, the formed CTL may have poor homogeneity, and the desired characteristics may not be obtained.

Following such heating and melting, the molten selenium raw material is held at a temperature lower than the heating temperature during heating and melting and at a holding temperature at which the molten state is maintained, for example, 240 to 360°C,
Preferably, the temperature is lowered to a range of 260 to 320°C, and the melt is maintained at the holding temperature for a certain period of time, for example, 30 minutes or more, while stirring to maintain uniformity of the composition.

Preferably, the temperature is lowered from the heating temperature to the holding temperature rapidly. If the holding temperature is too low, the melt will solidify, which is not preferable. It is sufficient for the time to be maintained at the holding temperature to be 30 minutes or more, but in practice it is preferably within the range of 30 to 120 minutes.

After being maintained at the holding temperature for a certain period of time, the molten material is poured into water, for example, and rapidly cooled to approximately room temperature to solidify it, and the solidified material is recovered and the tellurium content is 12% by weight. A first photoreceptor material containing less than halogen is obtained.

Practically speaking, the content of halogen in the first photoreceptor material is preferably within the range of 5 to 100 ppm by weight.

The second photoconductor material used as the CGL material in the present invention, which has a tellurium content of 12 to 35% by weight and contains or does not contain a smaller proportion of halogen than the first photoconductor material, is as follows: Manufactured as follows.

That is, selenium, tellurium, selenium halides and/or
Alternatively, a selenium raw material is prepared by adding a tellurium halide in a required ratio. The selenium, tellurium, selenium halides, and tellurium halides that make up this selenium raw material are crushed ingots, granular ones,
It may be in any of various forms such as powder,
A granular or powdered material is preferable because it can be easily melted, and the particle size is preferably, for example, 0.5 to 5 mm in diameter. Examples of halogen elements that form selenium halides or tellurium halides include fluorine, chlorine, bromine, and iodine.
More than one type of halide may be included. In addition, this selenium raw material contains property improvers such as copper, platinum,
Gold or the like may be contained, for example, in a proportion of 1 to 100 ppm by weight.

Such a selenium raw material is heated and melted. For example, a selenium raw material is placed in a crucible and placed in a vacuum atmosphere or an inert gas atmosphere such as helium, argon, or nitrogen.
Using an electric oven or the like, the temperature is rapidly or stepwise raised from room temperature to a temperature in the range of 380 to 450°C, and the melt is heated and melted, and the molten material is maintained at a constant heating temperature for usually 30 to 240 minutes. Preferably, the selenium raw material is continuously stirred using a screw stirrer or the like for 60 to 180 minutes to sufficiently homogenize the composition of the melt. The heating temperature for melting the selenium raw material is a temperature at which the selenium raw material melts and the melting point of tellurium (450
℃) or less, and the range is 380 to 450℃. If this heating temperature exceeds 450°C, some of the CGL formed from the obtained second photoreceptor material may be easily crystallized at high temperatures, and crystallization at high temperatures can be surely suppressed. It doesn't become something. The heating temperature can be lowered as the tellurium content is lower, but if it is lower than 380°C, melting will be insufficient and tellurium will segregate in the resulting second photoreceptor material. Therefore, the formed CGL may have poor homogeneity, and the desired characteristics may not be obtained.

Following such heating and melting, the molten selenium raw material is held at a temperature lower than the heating temperature during heating and melting and at a holding temperature at which the molten state is maintained, for example, 250 to 420°C,
Preferably, the temperature is lowered to a temperature in the range of 260 to 360° C., and the melt is maintained at the holding temperature for a certain period of time, for example, 30 minutes or more, while stirring to maintain uniformity of the composition.

Preferably, the temperature is lowered from the heating temperature to the holding temperature rapidly. If the holding temperature is too low, the melt will solidify, which is not preferable. It is sufficient for the time to be maintained at the holding temperature to be 30 minutes or more, but in practice it is preferably within the range of 30 to 180 minutes.

After being maintained at the holding temperature for a certain period of time, the molten material is poured into water, for example, and rapidly cooled to approximately room temperature to solidify it, and the solidified material is collected to reduce the tellurium content to 12 to 35. A second photoreceptor material is obtained which contains or does not contain halogen in a weight percent smaller than that in the first photoreceptor material.

The content of halogen in the second photoconductor material may be smaller than that in the first photoconductor material, but
Practically speaking, it is preferably less than 5 weight ρpm, and in some cases, it may be 0 weight ρpm, that is, no halogen may be contained. Further, if the content of halogen in the second photoreceptor material is higher than that in the first photoreceptor material, the effect of adding halogen becomes meaningless.

The manufacturing examples of the first photoreceptor material used as the CTL material and the second photoreceptor material used as the CGL material have been described above, and the first and second photoreceptor materials obtained in this way CTL and CG using
As a means for forming L, for example, a vapor deposition method can be cited as a preferable method. Specifically, for example, as shown in FIG.
A vapor deposited film of the photoreceptor material is provided to form CTL3, and a vapor deposited film of the second photoreceptor material described above is provided on this CTL a to form CGL 2, and these CGL 2 and CT
L 3 constitutes the photosensitive layer 4.

Here, as the material of the conductive support 1, for example, a sheet of metal such as aluminum, nickel, copper, zinc, palladium, silver, indium, tin, platinum, gold, stainless steel, or brass can be used.

The thickness of the CGL 2 is usually 1-10 microns, preferably 2-5 microns. The thickness of the CTL 3 is usually 30 to 100 microns, preferably 50 to 60 microns.
It is micron.

〔Effect of the invention〕

Since the electrophotographic photoreceptor of the present invention has the above structure,
As will be understood from the description of the examples below, the crystallization of the photosensitive layer at high temperatures is reliably suppressed, and therefore even when exposed to high temperatures, the photosensitive layer still has sufficient dark resistance. Moreover, it has sufficiently high photosensitivity and good photoconductivity, and as a result, even when the electrophotographic process is repeated many times, the increase in residual potential is greatly suppressed, and it is not affected by the environmental temperature. The electrophotographic process can be stably repeated for a long period of time without any problems. The reason why such an effect is obtained has not been strictly elucidated, but in the production of the first and second photoreceptor materials that form the CTL and CGL of the photosensitive layer, the selenium raw material is specified to have a temperature below the melting point of tellurium. Heat and melt at a heating temperature within the range,
Next, the molten material is not cooled all at once, but held at a temperature slightly lower than the heating temperature at which it can still maintain its molten state for a certain period of time, ensuring that the resulting selenium substance has the property of being resistant to crystallization. It is thought that this property is inherited as it is when it becomes CTL and CGL, and as a result, even when it contains tellurium, crystallization at high temperatures in CTL and CGL is reliably suppressed. .

CGL is formed by vapor-depositing the second photoreceptor material for CGL, which has been described above, so that the tellurium content ratio is 1.
Since it has a content of 2 to 35% by weight, it has high photoconductivity and an excellent carrier generation function.
By forming the first photoreceptor material for L by vapor deposition, the tellurium content is less than 12% by weight, so it has low dark decay, high charge retention, and excellent carrier transport function. Become something.

Furthermore, since halogen is uniformly contained in each of the first and second photoreceptor materials, as a result, the required amount of halogen is also reduced in CTL and CGL formed by vapor-depositing these photoreceptor materials. Since the halogen is contained in a uniformly dispersed state, the effect of adding halogen is
Each of L and CGL can be obtained in a unique manner and uniformly over the entire photosensitive layer, and as a result, a photosensitive layer with constant photosensitive characteristics and no unevenness in characteristics can be obtained.

In addition, in the formation of a photosensitive layer with a two-layer structure of CGL and CTL, the evaporation source is changed and the evaporation is repeated until "0" is performed, but during the second evaporation, the evaporation film is heated while the first evaporation film is being deposited. Even if this is done, crystallization of the first vapor-deposited film does not occur, and therefore good vapor deposition can be performed without deterioration of photosensitivity, and the resulting photosensitive layer has good photosensitivity. It will have the following.

〔Example〕

Examples of the present invention will be described in detail below, but the present invention is not limited to these examples.

Example 1 (Production of wood powder material for CGL) Approximately 78% by weight of granular selenium (purity 9
9.999%), about 22% by weight of granular tellurium (99% purity)
．． A selenium raw material consisting of granular selenium chloride (purity 99.999%) and 2 ppm by weight was melted by rapidly raising the temperature from room temperature to 390°C in an electric furnace with a nitrogen gas atmosphere. The melt was kept at the heating temperature for 60 minutes while being stirred by a screw stirrer. Subsequently, the melt was rapidly lowered to a holding temperature of 300° C. at which it remained in a molten state, and the melt was held at the holding temperature for 30 minutes while being stirred by a screw stirrer. Following this holding, the molten material in the crucible was poured into water at a temperature of 20.degree. C. through a nozzle made of quartz and having a diameter of 2 weight, and was rapidly cooled and solidified. Next, the solidified material was recovered from the water to obtain a second photoreceptor material made of a selenium substance containing about 22% by weight of tellurium and halogen.

(Manufacture of CTL material) Approximately 95% by weight granular selenium (purity 9
9.999%), approximately 5% by weight of granular tellurium (99.99% purity).
A selenium raw material consisting of granular selenium chloride (99.999%) and 30 ppm by weight (purity 99.999%) is melted by rapidly raising the temperature from room temperature to 380°C in an electric furnace with a nitrogen gas atmosphere. The melt was kept at that heating temperature for 60 minutes while being stirred with a screw stirrer6.Then, the melt was rapidly lowered to a holding temperature of 300°C at which the melted state was still maintained, and the melt was stirred with a screw. The holding temperature was maintained for 30 minutes while stirring with a vessel. Following this holding, the molten material in the crucible was poured into water at a temperature of 20.degree. C. through a nostle made of quartz with a diameter of 211 mm, and rapidly cooled and solidified. Next, the solidified material is recovered from the water and about 5% by weight of tellurium and the second
A first photoreceptor material made of a selenium substance containing halogen in a higher proportion than that in the photoreceptor material was obtained.

The first photoreceptor material obtained as described above was used as an evaporation source and was heated and evaporated at a temperature of 280°C by a vacuum evaporation method to form a cylindrical conductive support made of aluminum and having a thickness of 4 mm. A film W-60 micron CTL was formed on top. Using the second photoconductor material obtained as described above as an evaporation source, the CTL was heated and evaporated at a temperature of 280°C by a vacuum evaporation method to form a CG film with a thickness of 5 microns.
L was formed, thereby obtaining an electrophotographic photoreceptor having the same structure as shown in FIG. This will be referred to as "Sample 1".

Examples 2 to 5 and Comparative Examples 1 to 4 Electrophotographic photoreceptors were obtained in the same manner as in Example 1, except that the manufacturing conditions for photoreceptor materials for CGL or CTL were as shown in Table 1 below. . These are "sample 2" to "
"Sample 5" and "Comparative Sample 1" to "Comparative Sample 4."

FIGS. 2 to 16 are diagrams schematically showing the relationship between temperature and time during the production of photoconductor materials, and show the relationship between CGL material molding and CTL material in each of the above Examples and Comparative Examples. In the production of raw materials, processing is performed according to one of the curves a - o shown in Figures 2 to 16, respectively, and the correspondence relationship is shown in the column "a" in Figure 1 in Table 1.
-What is the sign of o?

Each of the samples and comparative samples obtained as described above was installed in an electrophotographic copying machine rU-Bix 1600J (manufactured by Konishiroku Photo Industries Co., Ltd.), and charged and exposed in an environment of a temperature of 20°C and a relative humidity of 65%. A test was conducted to investigate the charging potential and residual potential. The charging potential is 6. OKV,
Evaluation was made using the surface potential measured with a surface electrometer probe placed at the developing area under charging conditions of 200μ. Regarding the residual potential, the surface of the photosensitive drum is
After charging to 00OV, the exposure amount is 201ux-s
The process of exposing halogen light to ec
After repeating 0 times, the potential accumulated on the surface of the photosensitive drum was measured, and this was taken as the residual potential.

Next, remove the above sample and comparative sample and heat them to 6
A forced deterioration treatment was performed by leaving it in an environment of 0° C. and 50% relative humidity for 3 days, and then the same test was conducted again to examine the charged potential and residual potential.

In addition, each of the samples prepared in the same manner as described above and the comparative samples were left in a constant temperature bath maintained at a temperature of 65°C and a relative humidity of 50% to forcibly cause thermal deterioration of the photosensitive layer. We investigated the time it takes for the skin to start turning white. The surface of the photosensitive layer becomes white because the amorphous structure is changed by heat and crystallization progresses, and the longer this time, the better the high temperature durability.

The results of the above tests are also shown in Table 1.

As can be understood from the results in Table 1, according to Samples 1 to 5, which are electrophotographic photoreceptors of the present invention, the photosensitive layer has excellent high-temperature durability and even when exposed to high temperatures. It still maintained a high charging potential and had a small residual potential, making it possible to stably repeat the electrophotographic process many times. On the other hand, comparative samples 1 and 2 have C
The first and second photoreceptor materials for forming the TL and CGL are manufactured by cooling them all at once without going through a process of holding them at a holding temperature, so this material was used to produce the material. The photosensitive layer has extremely low high-temperature durability, and when exposed to high temperatures, the charged potential decreases considerably and the residual potential increases significantly, making it impossible to put it into practical use at an early stage.

Comparative samples 3 and 4 were heated at a heating temperature of 370°C, although the first and second photoreceptor materials for forming CTL and CGL underwent a process of holding at a holding temperature for a certain period of time or more during manufacture. ~430℃ and 380~4
Since the temperature was outside the range of 50° C., photosensitive layers prepared using these photoreceptor materials had slightly poor high-temperature durability, and crystallization at high temperatures could not be reliably prevented. Comparative sample 4 did not contain any halogen and therefore had a high residual potential.

Further, a photoreceptor was prepared in the same manner as described above except that the heating temperature of the evaporation source was changed, and when the same test was performed, results similar to those described above were obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view showing an example of the structure of the electrophotographic photoreceptor of the present invention, and FIGS. 2 to 16 show the relationship between temperature and time during the production of photoreceptor materials for CGL or CTL, respectively. It is a line diagram showing an outline. 1... Conductive support 2... Carrier generation layer (ceL) 3... Carrier transport layer (CTL) 4... Photosensitive layer Figure 1 Figure 2 Figure 6 Figure 4 5, fig.

Claims (1)

[Scope of Claims] 1) An electrophotographic photoreceptor in which a photosensitive layer comprising a combination of a carrier generation layer and a carrier transport layer is provided on a conductive support, wherein the carrier transport layer contains a selenium raw material of 370 to 430%. ℃
A first material having a tellurium content of less than 12% by weight and containing halogen, obtained by heating and melting at a temperature within the range of The carrier generation layer is formed from a material for a photoreceptor, in which the selenium raw material is heated and melted at a temperature within the range of 380 to 450°C, then held at a temperature lower than the heating temperature for a certain period of time or more, and then cooled and solidified. A second photoconductor material containing 2 to 35% by weight of tellurium and containing or not containing a smaller proportion of halogen than the first photoconductor material. An electrophotographic photoreceptor characterized by: