JPH03152545A - Production of photosensitive body - Google Patents

Abstract

PURPOSE:To prevent the degradation and fluctuation in surface potential by using an org. solvent of a non-halogen system for cleaning of a surface. CONSTITUTION:The non-halogen solvent is the solvent constituted of the molecules which do not contain halogen atoms as its constituting atoms and includes satd. hydrocarbons, hydrocarbon alcohols, arom. hydrocarbons, ketones or ethers, etc. A dipping method, shower method, steam cleaning method, etc., may be applied to the method of cleaning the photosensitive body. A surface protective layer (vacuum thin film) can be formed with good adhesiveness by various methods, such as plasma CVD method, photo CVD method, thermal CVD method, sputtering method, vapor deposition method, and ion plating method, on the surface of the photosensitive body cleaned in such a manner. The good photosensitive body which is free from the degradation in the surface potential, the fluctuation in the surface potential, etc., is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing an organic photoreceptor having a protective layer on its surface.

BACKGROUND OF THE INVENTION Organic photoreceptors are generally manufactured by forming an organic photoreceptor on a conductive substrate and then forming a surface protective layer.

Ideally, it is desirable to form the surface protective layer on the surface of the organic photosensitive layer immediately after forming it, but in reality,
To simplify the manufacturing process and due to equipment problems, it is common to manufacture large quantities of organic photosensitive layers at one time, and then use them to form a surface protective layer such as an amorphous carbon film. During this period, the organic photosensitive layer is often stored for several days to one month (this storage period is referred to as "starting time").

After formation, the surface of the organic photosensitive layer is oxidized by oxygen in the atmosphere over time. When attempting to provide a protective layer, such as an amorphous carbon film, on the surface of an organic photosensitive layer on which such an oxide film has been formed, the surface protective layer may be damaged due to poor adhesion between the oxide film surface and the protective layer. Peeling will occur. According to the experience of the present inventors, this phenomenon is already likely to occur in organic photosensitive layers that have been coated for several days.

In order to remove such an oxide film, conventionally, the surface of the organic photosensitive layer has been washed with a general halogen-based cleaning solvent typified by Freon. Although this method certainly removes the oxide film and ensures the adhesion between the photosensitive layer and the surface protective layer, there is a problem in that the organic photosensitive layer deteriorates and the surface potential decreases and varies.

Incidentally, an electrophotographic photoreceptor having a surface protective layer formed of a vacuum thin film is disclosed in, for example, JP-A No. 62-100766 and (32-29).
4258,51-139340,49350361,1
18-128732, 49-122337, 58-59
454, 61-117562, 58-152255, (
33-97'1) 62, etc., but before forming a vacuum thin film on the surface of a photosensitive layer that has been stored for a long time, it is necessary to clean the photosensitive layer to be coated to ensure adhesion. Nothing was said or implied about it.

Problems to be Solved by the Invention The present invention has been made in view of the above circumstances, and it effectively removes the oxidized layer of the organic photosensitive layer, secures the adhesion of the surface protective layer to the photosensitive layer, and further improves the surface It is an object of the present invention to provide a method for manufacturing a photoreceptor without potential drop or variation.

This object is achieved by using a non-halogen organic solvent in place of the conventional halogen cleaning solvent for cleaning the surface of the organic photoreceptor.

Means for Solving the Problems Specifically, the present invention provides a method for manufacturing a photoreceptor in which a vacuum thin film is provided as a surface protective layer on an organic photosensitive layer, in which the photosensitive layer is coated with a non-halogen solvent before being coated with the vacuum thin film. The present invention relates to a method for manufacturing a photoreceptor, which is characterized in that it is washed.

The non-halogenated solvent used in the present invention is a solvent composed of molecules that do not contain halogen atoms as constituent atoms, such as n-hexane, cyclohexane, pentane, cyclopentane, hegetane, octane, ligroin, petroleum ether, etc. , saturated hydrocarbons such as benzine, isohexane, neohexane, ■-hexene, hydrocarbon alcohols such as methanol, ethanol, propatool, butyl alcohol, allyl alcohol, benzyl alcohol, toluene, xylene, hemimelithene, pseudocumene, tetralin Examples include aromatic hydrocarbons such as, ketones such as acetone, ethyl methyl ketone, cyclohexanone, methyl vinyl ketone, and ethers such as ethyl ether and methyl ether. Preferred are n-hexane and inhexane.

The organic photosensitive layer for which cleaning with a non-halogenated organic solvent is effective is not particularly limited, but it is necessary that the outermost layer before forming the surface protective layer is composed of a dispersed layer of resin. . That is, charge generating substances such as phthalocyanine pigments, azo pigments, perylene pigments, etc. and charge transport substances such as triphenylmethane compounds, triphenylamine compounds, hydrazone compounds, styryl compounds, pyrazoline compounds, oxazole compounds, and oxadiazole compounds. etc., a binding material such as polyester, etc.
A single-layer structure made by dispersing and coating polyvinyl butyral, polycarbonate, polyarylate, styrene acrylic, etc., or one in which a charge generation substance and a charge transport substance are dispersed and coated in separate layers to separate charge generation and charge transport functions. It is applicable to any function-separated structure (the stacking order may be arbitrary). However, there are charge generation layers that are made of only the charge generation substance itself without using a binder resin, such as a vapor-deposited film of phthalocyanine, but even if it is composed of such a charge generation layer, The cleaning of the present invention is effective if a resin-separated charge transport layer is provided.

As a method for cleaning the photoreceptor, a dipping method, a shower method, a steam cleaning method, etc. may be applied, and the cleaning conditions are as follows.
Type of photoreceptor (monodisperse, functionally separated type), type of constituent resin,
It may be selected and set as appropriate depending on the type of solvent used.

A dipping method is preferred; in this cleaning method, the photoreceptor is
It is sufficient to immerse it in hexane solvent at 0° C. for about 60 seconds. To increase the cleaning effect, apply ultrasonic vibration,
The solvent may be (purified) circulated.

A surface protective layer (vacuum thin film) is applied to the surface of the photoreceptor thus cleaned by various methods such as plasma CVD, photoCVD, silent CVD, sputtering, vapor deposition, and ion blating. can be formed with good adhesion, and the resulting photoreceptor can be of good quality without a decrease in surface potential or variation in surface potential.

Hereinafter, the present invention will be explained in more detail with reference to examples.

EXAMPLES Preparation of organic photosensitive layers (a) to (') Organic photosensitive layers (a) to (f) were prepared as follows.

Among these photosensitive layers, the photosensitive layer (b) is for positive charging, and the other photosensitive layers are for negative charging.

Further, the photosensitive layer (f) is used for long wavelength exposure, and the other photosensitive layers are used for normal white light exposure.

Preparation of organic photosensitive layer (3) Hisazo pigment chlorodiane blue (CDB) 1 part by weight,
Polyester resin (manufactured by Toyobo Co., Ltd.; V-200) I
A mixed solution of 1iIk parts and 100 parts by weight of cyclohexanone was dispersed in a sand grinder for 13 hours. This dispersion was applied by dipping onto a cylindrical aluminum substrate with a diameter of 80 mm and a length of 330 mm, and dried to a film thickness of 0.
．． A charge generation layer of 3 μm was formed.

Separately, 1 part by weight of 4-diethylaminobenzaldehyde-diphenylhydrazone (DEH) and 1 part by weight of polycarbonate (manufactured by Teijin Kasei Co., Ltd.; Ni-1300) were dissolved in 6ffiig+ of tetrahydrofuran (Tt+p), and this solution was applied onto the charge generation layer. It is coated and dried to form a charge transport layer with a film thickness of 15 μn1 after morning drying, and an organic photosensitive layer (a
) was obtained.

Preparation of organic photosensitive layer (b) 25 parts by weight of special α-type copper phthalonanine (manufactured by Toyo Ink Co., Ltd.), acrylic melamine thermosetting resin (manufactured by Dainippon Ink Co., Ltd.; mixture of A-405 and Super Beckamine J820)
A mixture of 50 parts by weight, 25 parts by weight of 4-diethylaminobenzaldehyde-diphenylhydrazone, and 500 parts by weight of an organic solvent (a mixture of 7 parts by weight of xylene and 3 parts by weight of butanol) was pulverized and dispersed in a ball mill for 10 hours. This dispersion was applied by dipping onto a cylindrical aluminum substrate with a diameter of 80 mm and a length of 330 mm, and dried and baked (150° C. for 1 hour) to obtain an organic photosensitive layer (b) with a thickness of 15 μm.

Preparation of organic photosensitive layer (c) 2 parts by weight of a bisazo compound represented by the following formula [Ial, 1 part by weight of polyester resin (manufactured by Toyobo Co., Ltd., V-500),
and 100 parts by weight of methyl ethyl ketone were mixed and dispersed in a ball mill for 24 hours. The diameter of this dispersion is 80mm.
It was coated on a cylindrical aluminum substrate with a length of 330 mm by dipping and dried to obtain a charge generation layer with a thickness of 3000 mm.

Next, 10 parts by weight of a hydrazone compound represented by the formula [lb] below and 10 parts by weight of polycarbonate resin (manufactured by Teijin Kasei Co., Ltd., Ni-1300) were dissolved in 80f [11 parts of tetrahydrofuran] on this charge generation layer. The liquid was applied and dried to form a charge transport layer with a thickness of 20 pm, thereby obtaining an organic photosensitive layer (C).

Preparation of organic photosensitive layer (d) 2 parts by weight of a bisazo compound represented by the following formula [11a],
1 part by weight of polyester resin (manufactured by Toyobo Co., Ltd., V-500) and 1 ooffi part of methyl ethyl ketone were mixed and dispersed in a ball mill for 24 hours. The diameter of this dispersion is 80 mm.
It was coated on a cylindrical aluminum substrate with a length of 330 mm by dipping and dried to form a charge generation layer with a thickness of 2500 mm.

Then, a styryl compound 1 represented by the following formula [I[b]
0 parts by weight, and polyarylate resin (manufactured by Unitika;
U-4000) I 0 parts by weight to 85% of tetrahydrofuran
Parts by weight were dissolved. The resulting coating solution was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 20 μm, thereby obtaining an organic photosensitive layer (d).

Preparation of organic photosensitive layer (e) 2 parts by weight of a bisazo compound shown in the following formula [n1al, 1 part by weight of polyester resin (manufactured by Toyobo Co., Ltd.; V-500),
and methyl ethyl ketone 100! Part ii was mixed and dispersed in a ball mill for 24 hours. The diameter of this dispersion is 80m.
It was applied by dipping onto a cylindrical aluminum substrate having a length of 330 nm and a length of 330 nm, and was dried to form a charge generation layer having a thickness of 3000 nm.

Then, styryl compound 10 shown in the formula [I[1b] below
parts by weight, and 10 parts by weight of methyl methacrylate resin (manufactured by Mitsubishi Rayon Co., Ltd.; BR-85) were dissolved in 80 parts by weight of tetrahydrofuran. The obtained liquid was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 20 μm, and an organic photosensitive layer (e) was applied thereto.

Preparation of organic photosensitive layer (f) Natanyl phthalocyanine (TiOPc) was heated to a port temperature of 400 to 500° C. and a vacuum degree of 10-' using a resistance heating method.
-10-'Torr vacuum evaporation, thickness 2500
A TiOPc vapor-deposited film was formed as a charge generation layer.

Next, parts by weight of p,p-bisdiethylaminotetraphenylbutadiene In shown in the formula [rV] below and 1 part by weight of polycarbonate (manufactured by Teijin Kasei Co., Ltd., Ni-1300) were added to T.
It was dissolved in 6 parts by weight of HF, and this solution was applied onto the charge generation layer and dried to form a charge transport layer having a thickness of 15 μm, thereby obtaining an organic photosensitive layer Cf).

[Formula 111a] [Formula 1 [1b] [Formula ■] The photosensitive layer (a) obtained as described above has 20'(!
, 65% for 30 days, and then washed using the washing apparatus shown in FIG.

In FIG. 1, (1) is a photosensitive drum (1) having a photosensitive layer (a) provided on a base, and a means (3) having a hydraulic vertical mechanism.
It is attached to a vertically movable shaft (2). (
4) is a cleaning tank, which has an internal volume of 30 (vertical) x 30 (horizontal) x 50 (height to liquid level) am3, and is filled with a cleaning solvent (5). The solvent (5) is recycled in the distillation circuit (6).

For cleaning, first, the photosensitive drum (1) is
) to gradually lower the photosensitive drum (
1) by immersing the entire sample.

At this time, in order to perform cleaning more effectively, ultrasonic cleaning is appropriately performed using an ultrasonic oscillator (7).

The amount of solvent used for actual cleaning was approximately 5H, including the distillation circulator (6) and piping. The liquid temperature was set at 20°C using a temperature controller (not shown). The output of the ultrasonic oscillator used appropriately was 500W.

In the above cleaning process, using the solvents shown in Table 1,
Immersion operation time, immersion time, US time shown below,
and the pulling motion was measured. The results are shown in Table 1.

■Immersion operation: The time from when the bottom end of the photosensitive drum touches the liquid surface until the top end is immersed in the liquid surface while lowering the shaft at a constant speed.

In other words, a drum with a length of 330 mm In this case, dipping operation 3 shown in Example 1 0 [1 second is 330/30- This means that the shaft was lowered at 11 mm/sec.

■Immersion time: The time the entire photosensitive drum is immersed under the liquid surface.

(2) US time: When an ultrasonic (US) oscillator was used, the time during which ultrasonic waves were oscillated within the immersion time was shown.

■Lifting operation: The opposite of dipping operation, the time from when the top of the photosensitive drum comes out above the liquid surface until the bottom of the photosensitive drum comes out.

In addition, the difference in immersion time in the liquid between the bottom end of the drum and the top end of the drum,
The shortest and longest times were measured as shown below and are shown in Table 1 as the drum surface cleaning time difference.

■Minimum time: The time the top of the drum is submerged below the liquid level.

That is, it is equal to the immersion time.

■Maximum time 2: The time the bottom end of the drum is submerged under the liquid level.

In other words, the dipping operation element dipping time + pull Equivalent to upward motion.

After cleaning the photosensitive layers (b) to (f), the photosensitive layers (b) to (r) were also stored in an environment of 20°C and 165% for 30 days.
Washed under the conditions shown in .

Formation of surface protective layer After cleaning the photosensitive layer, a surface protective layer was provided on the surface of the photosensitive layer (a) as follows.

In the glow discharge decomposition apparatus shown in FIG. 2, first, the inside of the reactor (733) is made into a high vacuum of about IO-'' Torr, and then the first and second control valves (707 and 70
8) and hydrogen gas from the first tank (7 ol) and butadiene gas from the second tank (702) at an output pressure of 1
, 0 Kg/cm2 into the first and second flow controllers (713 and 714). Then, adjust the scale of each flow rate controller to increase the hydrogen gas flow rate to 300.
secm, the flow rate of butadiene gas is set to 3 Q sccm, and the flow rate is set to 3 Q sccm,
It flowed into the reaction chamber (733) from the main pipe (732). After each flow rate became stable, the pressure control valve (745) was adjusted so that the pressure in the reaction chamber (733) was 0.5 Torr. On the other hand, as the substrate (752), use the organic photosensitive layer (a), heat it to 50°C in advance, and with the gas flow rate and pressure stable, connect the connection selection switch (752) in advance.
The low frequency power source (741) connected to the substrate (752 ) top thickness 12
An amorphous carbon film (a-C film) of 0.00% was formed as a surface protective layer. After the film formation was completed, the application of electric power was stopped, the control valve was closed, and the inside of the reaction chamber (733) was sufficiently evacuated, and then the vacuum was broken and the photoreceptor of the present invention was taken out.

Photosensitive layers (b) to (f) were also formed in the same manner as above under the conditions shown in Table 1.

(Hereafter, blank space) Measurement of photoreceptor surface potential (before surface protective layer formation) As shown in Figure 3, a photosensitive drum (lO) before forming a surface protective layer was attached and rotated at a circumferential speed of 130 mm/SeC. . High voltage power supply (12XMODEL610A, TR
Corotron charger (13) receives power from EK Corporation)
The surface of the photosensitive layer was charged to 500V. The charging potential was measured using a surface electrometer (+4XMODEL362A; TRE
(manufactured by K Company), and the current aμA at that time was measured with an ammeter (II
) was read.

Three surface electrometers were installed in the longitudinal direction of the drum as shown in FIG. 4, and the potentials at the top, middle, and bottom of the drum were simultaneously measured during cleaning. In addition, the above-mentioned ammeter reading a[μ
A1 indicates the reading when the average of the three surface electrometers was 500 V. In all experiments, the variation in surface potential at the top, middle, and bottom of each drum was within ±5 V. Finally, the charged charge was charged using an eraser lamp (15X tungsten lamp, color temperature 2800°, 40 [1u
x-see]) was irradiated and erased.

(After forming the surface protective layer) Next, attach the photosensitive drum on which the surface protective layer has been formed, and adjust the output of the charger (13) so that the reading value of the ammeter (l l) becomes a [μA] again. Three surface potential meters (14) were used to read the surface potential at each position on the top, middle, and bottom of the drum, and the evaluation results were expressed using the following symbols according to the range of decrease from the initial surface potential of 500V.

(Variation evaluation) Evaluation results are shown according to the difference between the maximum value and the minimum value of the surface potential fluctuation within the circumference.

Evaluation of adhesion The adhesion of the surface protective layer was evaluated using a JIS-5400 base plate test, in which three parts (top, middle and bottom) of the photosensitive drum (FIG. 4) were exposed.

Regarding the V0 variation in the longitudinal direction, the maximum value 1i117 and the minimum value for the top, middle, and bottom three locations were evaluated in the same manner.

Image Evaluation The obtained photoreceptor (with a protective layer) was mounted on an actual copying machine, and the obtained copy image was visually judged.

As a copying machine, EP49oz (manufactured by Minolta) was used. However, the photoreceptor using the photosensitive layer (b) was modified so that the charging and developing polarity was reversed, and the optical system of the photoreceptor using the photosensitive layer (f) was modified to a semiconductor laser system. I used something.

O indicates a good image, Δ indicates an image with no practical problems), and × indicates an unsuitable image.

Table 2 summarizes the above evaluation results for each photosensitive layer.

(Hereinafter, blank space) In Examples 1 to 8, the cleaning method using n-hexane, which is a non-halogen solvent, was applied to the organic photosensitive layer (a), and the cleaning times were varied and evaluated. This is what was done.

When the cleaning time was short (Examples 1 to 3), although there were some cases where the adhesiveness was slightly poor, there was no practical problem, and overall, extremely good results were obtained compared to Comparative Examples 1 to 11. There is.

In Examples 9 to 11, it can be seen that if ultrasonic waves are used in combination, good adhesive properties can be obtained even in Examples 1 to 3, where the adhesive properties were slightly poor. In addition, in the case of Freon (Comparative Example 1-
It can be seen that the V0 drop as in 11) does not occur.

In Examples 12 to 15, it can be seen that even if the times of the dipping operation and the pulling operation are changed within a practical range, no difference in characteristics appears between the upper and lower sides of the photoreceptor.

In Examples 16 to 29, it can be seen that equivalent results can be obtained even if the organic photosensitive layer is changed to a layer other than (a).

In Examples 30 to 38, it can be seen that equivalent results can be obtained even when a non-halogen solvent other than n-hexane is used.

In Examples 39 to 44, it can be seen that equivalent results can be obtained even if the conditions for producing the a-C film are varied.

From the above Examples and Comparative Examples, it is understood that non-halogenated solvents are extremely effective for the purpose of the present invention.

Comparative Examples I2 to 17 were prepared using a-C surfaces without washing for photosensitive layers (a) to (f) (stored for 30 days after photosensitive layer preparation) to be used in the examples of the present invention. A protective layer is provided.

As shown in the adhesive evaluation, all adhesive ranks are X,
It is understood that the oxide film caused by long-term storage has a negative effect on the adhesion of the a-C film. Needless to say, if the a-C film is not adhered, the original purpose of the overcoat, which is to extend the life of the photoreceptor, cannot be achieved.

In addition, since natural peeling occurred without conducting a substrate surface test, there was a difference in surface potential between the areas with and without the overcoat layer. Although there is no practical problem in the dispersion evaluation, it is ranked △.

In image evaluation, as a result of peeling pieces a-C adhering to the copy image, peeling pieces getting into the developing device and getting caught between the height regulating plate and the developing sleeve, or between the photoreceptor and the developing sleeve,
To prevent the flow of developer from being obstructed and so-called development defects to occur.
This was an extremely unfavorable result. Image evaluation rank × indicates this.

In Comparative Example 1-11, a halogen-based solvent, which is often used as a cleaning agent for boat fishing, was used for the photosensitive layer (a), in contrast to the non-halogen-based solvent to be used in the examples of the present invention. -C Provides a surface protection layer! There are two things.

It can be seen that the adhesion is improved because the oxide film is removed.

However, if it is immersed in a halogenated solvent for too long or if a radical cleaning method using ultrasonic waves is used,
This leads to a decrease in surface potential after coating, and therefore Comparative Examples 3 to
In No. 11, the rank is ×. Since a decrease in image density due to this decrease in surface potential was also observed on the image, the image evaluation rank was expressed as ×.

On the other hand, if the time of immersion in the halogen-based solvent is too short, dripping may occur during cleaning, resulting in
That is, a difference in surface potential occurs between a portion where the solvent has been attached to the surface of the photoreceptor for a long time and a portion where the solvent has not been attached to the surface of the photoreceptor, and the Vo variation becomes large. V in Comparative Examples 1 to 5. This is the reason why the dispersion evaluation rank is ×.

Image noise with very noticeable drip-like shading also occurred on the image, so the image evaluation rank was expressed as ×.

As for the Vo variation, the rank becomes △ as the cleaning time with the halogen solvent increases. These are Comparative Examples 5 to 8.

This is because the difference in variation is only observed to be small because vo becomes low.

In the present invention, in place of the a-C film as the surface protective layer, a commonly used sputtering device is used under the following conditions: Target: Substrate temperature = 50°C Discharge interval: 50 mm (distance between target and substrate) Vacuum Degree 22 X l O-'Torr Discharge gas: Ar Release! Electricity + 2. OKW Discharge frequency: 13.56AIIz Discharge time: 12 minutes 00 layer film thickness: AQ20 at 1800A. Photoreceptors were produced and evaluated in the same manner as in Example 11, Comparative Example 1, and Comparative Example 12, except that the thin film was provided.

The results were equivalent to Example 1, Comparative Example 1, and Comparative Example 12.

In addition, instead of the a-C film as the surface protective layer, a commonly used evaporation apparatus using a vacuum heating method was used, and the following conditions were used: Vapor deposition source: SiO Substrate temperature = 50°C Port temperature: 1200°C Vacuum degree: 8 x 10 -5 Torr Vapor deposition time: 5 minutes 00 layer thickness: 130 OA Photoreceptors were produced and evaluated in the same manner as in Example 1, Comparative Example 1, and Comparative Example 12, except that a thin film of SiO was provided.

The results were similar to those of Example 11, Comparative Example 1, and Comparative Example 12.

From the above, it is understood that the present manufacturing method is applicable not only to a-C films but also to vacuum thin films in general.

Effects of the Invention It has become possible to form a vacuum thin film with good adhesiveness as a photoreceptor surface protective layer without causing a decrease in the surface potential of the photoreceptor or variations in the surface potential.

[Brief explanation of the drawing]

FIG. 1 shows an example of a schematic configuration of a photoreceptor cleaning device. FIG. 2 shows a schematic configuration example of a glow discharge decomposition apparatus for forming a surface protective layer. FIG. 3 shows an example of a schematic configuration of a photoconductor surface potential measuring device. FIG. 4 is a diagram showing the surface potential measurement site of the photoreceptor. Figure 1

Claims (1)

[Scope of Claims] 1. In a method for manufacturing a photoreceptor in which a vacuum thin film is provided as a surface protective layer on an organic photosensitive layer, the photosensitive layer is cleaned with a non-halogen solvent before being covered with the vacuum thin film. A method for manufacturing a photoreceptor characterized by: 2. The method for producing a photoreceptor according to claim 1, wherein the photosensitive layer is an organic photosensitive layer containing at least a charge-generating material and a charge-transporting material. 3. The method for manufacturing a photoreceptor according to claim 1, wherein the vacuum thin film is an amorphous carbon film produced by plasma CVD.