JPH03171141A - Manufacture of organic photosensitive body - Google Patents

Abstract

PURPOSE:To prevent drop of initial surface potential and occurrence of image noise by cleaning a support having a photosensitive layer with a solvent vapor at a temperature not above the boiling point and then forming a surface protective layer. CONSTITUTION:When the photosensitive body 10 to be cleaned is placed, kept at a room temperature, into a vessel filled with the solvent vapor 4 by evaporating a cleaning solvent 2, the vapor 4 is condensed on the surface of the photosensitive body 10 by the temperature difference of the body 10 and the vapor 4 and the solvent 2 in liquid drops cleans the body 10. When the temperature of the body 10 rises, the vapor comes not to condense, and the equilibrium of adsorbing and desorbing comes to be maintained. When the body 10 is drawn up, a drying step is made not only unnecessary but a danger of uneven drying can be eliminated, thus permitting rise of initial surface potential and occurrence of image noise to be prevented by cleaning the photosensitive body with the solvent vapor before forming an overcoat layer.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to organic photoreceptors (O
PC) improvements.

[Prior Art] OPC used in electrophotography and the like is widely used in copying machines. This OPC is usually made by first forming a charge generation layer containing a charge generation material on a base material such as aluminum.
A charge transport layer (CTL) containing a charge transport material is provided thereon, and a protective layer such as amorphous carbon (a-C) is provided thereon.

By the way, the a-C overcoat has poor adhesion to CTL. This is thought to be because the surface of OPC is oxidized, which acts to break the bond between a-C and OPC (CTL) interface.

At the same time, the stress that the a-C layer has also promotes this.

Therefore, it is effective to perform cleaning to remove the surface oxidation layer of OPC.

Conventionally, Freon-113 (chemical formula: CC12FCC/F
2) etc. were used as a cleaning solution to perform cleaning using the immersion method.

[Problems to be Solved by the Invention] However, in the conventional cleaning method of immersing the photoreceptor in a solvent, there is a problem in that the halogen-based solvent penetrates into the photoreceptor, and the halogen-based solvent causes deterioration of the characteristics of the photoreceptor. In particular, light irradiation decomposes the halogen-based solvent and releases active halogen, which is thought to have an adverse effect on OPC. In other words, when washed with a halogen-based solvent such as Freon-113, the Freon penetrates into the OPC, and the plasma discharge light when forming the overcoat further damages the OPC.
Decomposition of the solvent occurs. In addition, since a dense overcoat is formed, it becomes more difficult for the penetrating solvent to be released into the atmosphere.

Due to all of these influences, there was a problem in that only a photoreceptor with good adhesiveness but with deteriorated characteristics, particularly a reduced initial surface potential (Vo), could be obtained.

Immersion cleaning also had the following problems.

■ Uneven drying appears. This becomes image noise.

■ Dirt from the cleaning solution tends to adhere. This also results in image noise.

■ Solvent easily penetrates into the inside of OPC during soaking and drying. This causes a decrease in the initial surface potential (Vo).

■ Sonic waves (ultrasonic waves, vibrations) passing through the solvent tend to cause uneven cleaning. This also results in image noise.

In order to solve the problems of the prior art described above, the present invention performs steam cleaning with an organic solution before forming an overcoat layer to prevent a decrease in initial surface potential (■0) and to prevent image noise from occurring. Provided is a method for manufacturing an organic photoreceptor that prevents the above.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following structure.

That is, the present invention forms an organic photosensitive layer comprising at least a charge-generating material and a charge-transporting material on a support, or
In the method for producing an organic photoreceptor in which a surface protective layer is formed thereon, after forming the organic photoreceptor layer, the support having the photosensitive layer is kept at a temperature below the boiling point of the cleaning liquid, and the support is heated in the vapor region of the cleaning liquid. This is a method for producing an organic photoreceptor, characterized in that the organic photoreceptor is allowed to exist in the atmosphere, subjected to a steam cleaning treatment, and then a surface protective layer is formed.

In the present invention, preferably, the steam cleaning treatment is performed under the conditions represented by the following formula [I].

k. x H (Tb-Ts)≦t≦k
x It (Tb-Ts) [ Iman
max However, t: Steam cleaning treatment time (seconds) ■I: Heat capacity per unit surface area 1 [J-K-'・Cm-
1] Tb: Boiling point of the cleaning solution [KTS: Temperature of the support before cleaning ['f<] kmin,
k: proportionality constant, k, = 1, mln
mA!
mInk = 8 (unit: J-1・cnr
-sec') There is.

max [Function] According to the present invention having the above configuration, by performing steam cleaning of an organic solution before forming an overcoat layer, a decrease in the initial surface potential (Vo) is prevented and the generation of image noise is prevented. It is possible to obtain an organic photoreceptor in which the photoreceptor is protected.

The reason is as follows.

■ When the cleaning solvent is boiled and the solvent is vaporized, and the object to be cleaned (a photoreceptor) at room temperature is placed in the solvent vapor, the vapor liquefies on the surface of the photoreceptor due to the temperature difference between the photoreceptor and the steam, forming droplets. The photoreceptor is washed away.

As the temperature of the photoreceptor increases, vapor no longer liquefies on the surface of the photoreceptor, and an equilibrium state of adsorption and desorption of vapor is maintained. If the photoreceptor is pulled up in this state, not only is there no need for a drying step, but there is no worry about uneven drying.

■ Another advantage of this cleaning method is that the steam does not contain dirt, so it can be cleaned cleanly.

■ No disadvantages of immersion cleaning. That is, since the contact time of the solvent can be set to a minimum, there is little penetration of the solvent into the OPC. This can reduce characteristic deterioration.

The reason why the range of formula [I] is preferable is that the surface of the OPC can be sufficiently cleaned and there is little penetration of the solvent into the inside of the OPC. Specifically, it is best to finish cleaning as soon as the photoreceptor reaches a temperature sufficient to vaporize the solvent.

The temperature rise of the photoreceptor is determined by the heat capacity of the photoreceptor (substrate), the surface area of the photoreceptor, the temperature of the photoreceptor before cleaning, and the boiling point of the solvent. The reasons for the upper and lower limits of the formula [I] are as follows.

(a) When the upper limit of the cleaning time is exceeded, the temperature of the photoreceptor increases and the area around the photoreceptor becomes completely solvent vapor.

Since the solvent vapor easily permeates into the inside of the OPC, the characteristics tend to deteriorate (Vo decreases). Large image unevenness does not occur, but minute white spots (self-spots) tend to occur.

(b) When the cleaning time is less than the lower limit, the temperature of the photoreceptor is too low, and droplets remain attached around the photoreceptor.

Since cleaning is finished in this state, uneven drying is likely to occur.

This tends to appear as image noise.

[Example] The present invention will be described below in more detail using Examples. Note that the present invention is not limited to the following examples.

(1) Production method of photoconductive layer ■Preparation of CGL 1 g of chlorodiampule (CDB) as a disazo pigment Polyester resin (V-200 manufactured by Toyobo Co., Ltd.) 1
g Cyclohexanone 98 g or more of the mixed solution was dispersed with a sand grinder for 13 hours. This dispersion was applied onto a cylindrical aluminum substrate with a diameter of 80 mm using a dipping method so that the film thickness after drying would be 0.3 μm, and dried to form a charge generation layer (CGL).

■Preparation of CTL 5 g of a pyrazoline compound represented by the following structural formula [I] Polycarbonate (K-1300 manufactured by Teijin Kaoru Co., Ltd.) 1
0 g Tetrahydrofuran (THF) 50
Dissolve and mix more than
= 1/2 charge transport layer (first layer region) is placed on the CGL so that the film thickness after drying is 15 μm ■ Example of surface protective layer ■ Method Obtained by plasma polymerization, sputtering, ion plating, vapor deposition, etc. be able to.

■ Materials Inorganic oxides, inorganic fluorides, inorganic nitrides, inorganic carbides, non-quality hydrocarbons, etc., and impurities added to these,
and combinations thereof.

Specifically, Zr02, MgF2, Si3Na, AI2
03, MgO, SiC, SiO2, a-C:
}{,a-Si:C:HX a-Si:O:H,a
-Si:N:H etc. can be used.

(3) Examples used in Examples and Comparative Examples They are indicated by a and b below.

a. Formation method of surface protective layer (plasma polymerization = plasma C
In the case of VD) Next, a surface protective layer made of an organic plasma polymerized film was formed using a commonly used plasma polymerization apparatus under the conditions described below.

Gas used: hydrogen 300sccm butadiene
lQsecm Carbon tetrafluoride 10sec Film forming conditions: Pressure 0.2 Torr power supply; Low frequency power supply frequency 30 KHz Power 350 W Substrate temperature 50°C Film forming time 10 minutes Film thickness 1000 A b. Method for forming surface protective layer (sputtering method) According to a preferred embodiment of the present invention, Zr02, MgF2, Si3N4,
Si3N4: A1203, Si3N4: MgOSS
i3N4: An electrophotographic photoreceptor provided with a protective layer made of SiC or Si3N4:SiO2. Examples of the form and method of forming the protective layer of the present invention include sputtering method and vacuum evaporation method.

In the case of sputtering, a target made of the above compound is used, a sputtering gas such as Ar gas is introduced into the deposited layer, and sputtering is performed to form a thin film made of the above compound. The pressure of the Ar atmosphere may be within any range as long as glow discharge can be maintained, and is generally 0. 0 1~1. OTo r
r, 0.0 to obtain stable discharge. 1-1. OTo
It is desirable that it be rr.

Next, using a 13.56 MHz high frequency sputtering device, the atmosphere was changed to argon (Ar) gas O. 1Torr, and a 0.2μ thick Si3Na layer is placed on the carrier transport layer.
A photoreceptor having a protective layer of: S io2 (95:5) was prepared.

(4) Evaluation method Evaluation machine Copy machine EP490Zo manufactured by Minolta Camera ■ A Scorotron type charger is used as the main charger 6 Potential measurement A surface electrometer MODEL 344 manufactured by TREK is used. Set the measurement probe at the developing device position of EP490Z and measure the photoreceptor surface potential.

Printing durability test Using EP490Z, a printing durability test was conducted in an indoor environment using a chart with a B/W ratio of 6% and horizontally feeding A4 paper.

As an initial setting before continuous printing, the corona voltage is -6. 0kV
The output of the main charger was set so that

Adhesive Scotch (registered trademark) mending tape CAT. No. In the longitudinal direction of the photoconductor overcoated with 810-1-18 (tape width 18),
And after pasting it on the image area (length 297 mm), it is peeled off. After peeling off the tape, an overcoat film may adhere to the adhesive side of the tape. Total tape area of image area (
18 mm x 297 mm): On the other hand, the rank of adhesion was determined by the ratio of the area occupied by the tape to which the overcoat film was attached.

Ratio: Less than 1% ○ t % or more and less than 10% △ 10% or more × (5) Conditions and results Substrates for photoreceptors having various "heat capacities per unit surface area" were prepared. Examples 1 to 5 and Comparative Examples 1 to 5 used the same material (,AI), but by changing the thickness of the substrate,
The heat capacity per unit surface area is changed.

Here, the "heat capacity per unit surface area" H is expressed by the following formula.

H[erg-K-1・Cm-2]=C[erg-K-l
-g-l]×D[g-Cm-3]×d[Cm] C: specific heat, D: density, d: thickness A photoconductive layer was provided on these substrates. After storage for one week, cleaning was performed, and a surface protection (overcoat) layer was immediately formed. For the obtained photoreceptor, adhesiveness, initial surface potential (VO), variation of initial surface potential within the circumference of the photoreceptor, i
The surface potential (■0) after oooo printing was measured and evaluated. Only in Comparative Example 8, a surface protective layer was deposited without the cleaning step. As a result, there was a problem with adhesion and it could not be used.

The above results are shown in Tables 1 to 3.

As is clear from Tables 1 to 3, Examples 1 to 9 were within the scope of the present invention, and therefore good results were obtained.

On the other hand, in Comparative Example 9, the immersion cleaning method was adopted, so image noise occurred due to uneven drying, and the surface potential became 400 V or less either at the initial stage or after printing 10,000 sheets, and the image A decrease in concentration occurred, which was undesirable.

In addition, when the cleaning time is short as in Comparative Examples 4 and 6,
Poor adhesion and image noise due to uneven cleaning tend to occur. Furthermore, the initial surface potential varies widely within the circumference of the photoreceptor.

Comparative examples 1, 2, 3. 5. When the cleaning time is long as shown in item 7, minute white spot noise is generated, which is thought to be due to local charge injection.
At some point after printing 00 sheets, the surface potential becomes 400 V or less, and image density tends to decrease.

Examples 1 to 7 in which the washing time was appropriate had no problems in any of the characteristics.

In order to explain the steam cleaning method of the present invention in an easy-to-understand manner, the basic process will be explained using drawings. 1 to 3 show the basic process of the steam cleaning method of the present invention used in the above embodiments. In Figures 1 to 3, 1 is a cleaning tank, 2 is a boiling solvent, 3 is a heat source, 4 is a solvent vapor layer, 5
is cooling water, 6 is a condensate receiver, 7 is a condenser, 8 is cooling water,
9 is an air/steam interface, and 10 is a photoreceptor. Although not shown, a lid may be provided on the top of the cleaning tank 1.

When a cold photoreceptor 10 is placed in the solvent vapor layer 4 using the cleaning device configured as described above, the vapor condenses and liquefies on the surface of the photoreceptor due to the temperature difference between the photoreceptor and the vapor, forming droplets and cleaning the photoreceptor. Wash off (Figure 1).

As the temperature of the photoreceptor increases, the vapor no longer liquefies on the surface of the photoreceptor, and an equilibrium state of adsorption and desorption of vapor is maintained (Figure 2). If the photoreceptor is pulled up in this state, not only is there no need for a drying step, but there is no uneven drying (FIG. 3).

[Effects of the Invention] As explained above, the present invention prevents a decrease in the initial surface potential (Vo) and prevents the generation of image noise by performing steam cleaning of an organic solution before forming an overcoat layer. We were able to achieve the remarkable effect of being able to obtain a highly resistant organic photoreceptor.

[Brief explanation of the drawing]

Figures 1, 2, and 3 show the basic process of the steam cleaning method used in the embodiment of the present invention. 1: Cleaning tank 2: Boiling solvent 3: Heat source 4: Solvent vapor layer 5: Cooling water 6: Condensate receiving trough 7: Condenser 8: Cooling water 9: Air/steam interface 10: Photoreceptor 9: Air/steam Boundary surface Figure 1 Figure 3 Figure 2

Claims (1)

[Claims] (1) A method for producing an organic photoreceptor, in which an organic photoreceptor layer comprising at least a charge-generating material and a charge-transporting material is formed on a support, and a surface protective layer is formed on the organic photoreceptor layer. After formation, the support having the photosensitive layer is placed in the vapor region of the cleaning liquid while being maintained at a temperature below the boiling point of the cleaning liquid, and subjected to steam cleaning treatment, after which a surface protective layer is formed. Method for manufacturing an organic photoreceptor. 2. The method for producing an organic photoreceptor according to claim 1, wherein the steam cleaning treatment is performed under conditions represented by the following formula [I]. k_m_i_n×H(Tb-Ts)≦t≦k_m_a_
x×H(Tb-Ts) [I] However, t: Steam cleaning treatment time (seconds) H: Heat capacity per unit surface area [J・K＾-＾1・cm
^-^1] Tb: boiling point of cleaning liquid [K] Ts: temperature of support before cleaning [K] k_m_i_n, k_m_a_x: proportional constant, k
_m_i_n=1, k_m_a_x=8 (unit: J^-
^1・cm^2・sec).