JP2000084472A - Method for applying coating material to cylindrical substrate and production of electrophotographic photosensitive drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently form a uniform coating film to the outer peripheral surface of a cylindrical substrate by simple control. SOLUTION: In a method for coating a cylindrical substrate with a coating material supplied to a coating roll 2, the cylindrical substrate 1 and the coating roll 2 are rotated in the same direction and allowed to be spaced apart from each other in such a state that ribs are formed to the coating film on the cylindrical substrate 1. The cylindrical substrate 1 and the coating roll 2 are pref. rotated in the same direction in a non-contact state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying a coating material to a cylindrical substrate suitable for manufacturing a photosensitive drum for electrophotography and a method for manufacturing an electrophotographic photosensitive drum.

[0002]

2. Description of the Related Art An electrophotographic photosensitive drum has an undercoat layer (UCL) and a charge generating layer (C) on the outer peripheral surface of a hollow cylindrical base made of aluminum as an electrophotographic photosensitive paint.
GL) and a charge transport layer (CTL) are sequentially applied and laminated to form a photosensitive layer. The photosensitive layer is required to be a thin film and have a uniform thickness. However, since there is a strong demand for cost reduction, development and study of a coating method having excellent productivity are being conducted. As a method for forming a photosensitive layer by applying an electrophotographic photoreceptor coating to the outer peripheral surface of a cylindrical substrate, there have been conventionally known methods such as a spray coating method, a dip coating method, and a blade coating method. However, the conventional coating method has drawbacks such as a failure to obtain a uniform coating film and poor production efficiency.

For example, in the spray coating method, if a solvent having a low boiling point is used for the electrophotographic photoreceptor paint, the solvent contained in the paint volatilizes while the paint reaches the outer peripheral surface of the cylindrical substrate, and the solid content of the paint is reduced. Due to the increased concentration, when it reaches the cylindrical substrate, it does not spread sufficiently to the outer peripheral surface, and the coating surface becomes uneven, and the coating surface cannot be smooth and a uniform coating cannot be obtained. was there.

Conversely, when a solvent having a high boiling point is used, the paint adheres to the outer peripheral surface of the cylindrical substrate and leveling (uniformity of the film thickness, the same applies hereinafter) occurs. Fixation is delayed. Therefore, if the application is continued in a state where the coating is not sufficiently fixed, if the desired film thickness is large, paint dripping occurs, and a coating film having a uniform film thickness cannot be obtained. In order to avoid this, it is conceivable to apply the paint by dividing it into several times.However, it is conceivable to apply and dry the paint until it is dry to the touch (to the extent that no trace remains even when touched with a finger). It was necessary to repeatedly obtain a desired film thickness, which was time-consuming and extremely complicated.

According to the dip coating method, the smoothness of the surface of the coating film is improved, but the coating film is formed inside or on the end surface of the cylindrical substrate. Since the coating film formed on the inside or the end face of the cylindrical base becomes an obstacle when attaching a flange or the like, when the cylindrical base is used as a photosensitive drum for electrophotography, the coating on the inside or the end face of the cylindrical base is required. Once formed, the coating must be peeled off. Further, depending on the model used, the coating film once formed on the outer peripheral end of the cylindrical substrate must be peeled off, which requires a peeling step, which is a factor that hinders productivity.

Further, the thickness of the coating film is largely controlled by the physical properties of the coating material and the pulling speed after immersion. When the coating film is pulled at a constant speed, a difference in film thickness occurs between the upper end and the lower end of the cylindrical substrate. In order to solve this, it is necessary to control the pulling speed, but it is difficult to control it, and furthermore, it is necessary to slow down the pulling speed after immersion in order to form a uniform coating film. There was a problem, and high production efficiency could not be obtained.

[0007] The blade coating method is a coating method in which a blade is arranged at a position close to the longitudinal direction of a cylindrical substrate, paint is supplied to the blade, the cylindrical substrate is rotated once, and then the blade is retracted. Although high productivity can be obtained by this method, when the blade is retracted, a part of the coating film applied to the cylindrical substrate rises due to the surface tension of the coating material, so that the film thickness becomes uneven.

[0008] Furthermore, there is a roll coating method as a method other than the above method. The roll coating method is special in that the object to be coated is a cylindrical substrate, that is, the coating is performed once by rotating the cylindrical substrate as the object to be coated. The returned surface repeatedly returns to the application section, causing a problem that a paint pool is generated and the film thickness becomes non-uniform.

In order to avoid the occurrence of this paint pool,
For example, in Japanese Patent Application Laid-Open No. Hei 3-12261, when the cylindrical substrate makes one rotation and the paint is applied to the entire outer periphery thereof,
It has been proposed to separate the cylindrical substrate from the roll.
However, this requires fairly complex and precise control, and if the cylindrical body only makes one revolution,
It is difficult to obtain a uniform coating.

[0010] Further, the same publication discloses that after coating is completed by rotating the cylindrical substrate one or more times, the cylindrical substrate is separated from the paint supply roll, and the cylindrical substrate is continuously rotated to level the coating film surface ( A method for achieving uniform film thickness) is disclosed, but in this method, precise film thickness control must be performed in anticipation of the amount of paint pool to be leveled in advance.

Japanese Patent Application Laid-Open No. 2-222743 also discloses that
A method is disclosed in which only one layer of a paint film formed on the peripheral surface of the paint supply cylindrical roll is transferred to the outer peripheral surface of the cylindrical substrate, and the contact between the cylindrical substrate and the paint supply cylindrical roll is cut off. As described above, complicated and precise control is required.

The following problems have been pointed out when a thin coating film is formed by a roll coating method. That is, when the aluminum substrate for the photosensitive drum for electrophotography is rotated as the cylindrical substrate, a rotational deviation of about 50 μm occurs due to the accuracy of the cylindrical substrate itself and the accuracy of the rotation driving means. On the other hand, when the electrophotographic photoreceptor paint is composed of an undercoat layer, a charge generation layer, and a charge transport layer,
Since the thinnest charge generating layer has a thickness of sub-μm and the thickest charge transporting layer has a thickness of 30 to 50 μm, a coating film having a uniform thickness is formed in the state where the rotational blur occurs as described above. The essential problem of whether it can be done has been pointed out.

[0013]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional coating method and provides a method for efficiently forming a uniform coating film on the outer peripheral surface of a cylindrical substrate with a simple control. Things.

[0014]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the roll coating method in view of the above-mentioned situation, and found that a cylindrical substrate as an object to be coated and a roll for applying a paint to the cylindrical substrate were the same. Direction, and a stripe pattern (hereinafter referred to as a rib) generated when the ratio of the peripheral speed between the cylindrical substrate and the application roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the application roll) is large. It has been found that when the roll is separated in this state, the ribs are eliminated and the seam, which is a trace at the time of separation, is also eliminated, and a uniform coating film without a seam is formed on the cylindrical substrate.

The present invention is based on the above findings,
In a method of applying a coating material supplied to an application roll to a cylindrical substrate, a method is used in which the cylindrical substrate and the application roll are rotated in the same direction, and a rib is formed on the coating film on the cylindrical substrate. The present invention is characterized in that the cylindrical substrate and the application roll are separated from each other in the state where they are in the state of being held.

In the present invention, in order to smoothly apply the coating material supplied to the application roll to the cylindrical substrate, it is desirable that the application roll and the cylindrical substrate are rotated in the same direction in a non-contact state. Further, in the present invention, it is more preferable from the viewpoint of uniformity of the coating film thickness that, after the coating of the coating on the cylindrical substrate, the rotation is continued with the cylindrical substrate separated from the application roll.

According to the present invention, there is further provided a method of manufacturing an electrophotographic photosensitive drum in which an electrophotographic photosensitive coating material supplied to an application roll is applied to an electrophotographic photosensitive drum substrate and then dried. The body drum substrate and the application roll are rotated in the same direction, and the electrophotographic photosensitive drum substrate and the application roll are separated from each other while the ribs are formed on the coating film on the electrophotographic photosensitive drum substrate. It is characterized by. In this method of manufacturing a photosensitive drum for electrophotography, the ratio of the peripheral speed of the photosensitive drum base for electrophotography to the peripheral speed of the coating roll (the photosensitive drum base for electrophotography) Is between 2.0 and 15 when the coating material for the charge transport layer (CT coating material) is applied, and when the coating material for the charge generation layer (CG coating material) is applied. 1.0-3.0
And a method for manufacturing a photosensitive drum for electrophotography, which rotates in the same rotation direction in the range described above.

Hereinafter, a method of applying a coating material to a cylindrical substrate according to the present invention will be described in detail. First, the reason why the cylindrical substrate and the application roll (hereinafter, referred to as an applicator roll) are rotated in the same direction in the present invention will be described with reference to FIGS.

7 and 8, reference numeral 1 denotes a cylindrical substrate as an object to be coated, and 2 denotes an applicator roll, each of which rotates in the direction of an arrow (solid line). That is, FIG. 7 shows a case where the cylindrical base 1 and the applicator roll 2 rotate in the same direction, and FIG. 8 shows a case where the cylindrical base 1 and the applicator roll 2 rotate in opposite directions. I have. Paint 5
Means that the cylindrical substrate 1 and the applicator roll 2 are not in contact with each other,
That is, because of the predetermined gap, the applicator roll 2 is transferred and applied to the cylindrical substrate 1. The coating material 5 is affected by the rotation direction of the cylindrical substrate 1 and the applicator roll 2, and flows in the directions of the arrows (chain lines).

When the cylindrical substrate 1 and the applicator roll 2 rotate in opposite directions as shown in FIG. 8, the paint 5 applied to the cylindrical substrate 1 at the transition starting point 91 passes through the transition end point 92. It returns to the transition starting point 91 with the rotation of the cylindrical substrate 1. Therefore, a part of the paint 5 successively supplied by the applicator roll 2 cannot pass through the gap between the cylindrical substrate 1 and the applicator roll 2. The paint 5 that cannot pass is accumulated near the transition starting point 91 and forms a paint pool 8. When the cylindrical substrate 1 is separated from the applicator roll 2 in this state, that is, when the contact state via the paint is released, a portion corresponding to the paint pool 8 protrudes and impairs the uniformity of the paint film. It is conceivable that the cylindrical substrate 1 is separated from the applicator roll 2 before the paint pool 8 is formed. However, in such a case, the coating cannot be uniformly applied to the entire outer periphery of the cylindrical substrate 1.

On the other hand, as shown in FIG. 7, if the rotation direction of the cylindrical substrate 1 and the applicator roll 2 is set to the same direction, the paint accumulation does not occur, or the paint accumulation is small. That is, most of the paint conveyed by the applicator roll 2 reaches the transfer end point 92 from the transfer starting point 91 along with the rotation of the cylindrical base 1 via the outer peripheral surface of the cylindrical base 1. Therefore, even if the paint continues to be transferred from the applicator roll 2 to the cylindrical substrate 1, the paint pool 8 does not occur at the transfer start point 91. Even if it occurs, the amount is small, and can be eliminated to such an extent that there is no functional hindrance by leveling after the cylindrical substrate 1 is separated from the applicator roll 2.

Next, the ribs generated when the ratio of the peripheral speed of the cylindrical substrate to the peripheral speed of the applicator roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the applicator roll) is large are formed in a state where the ribs are formed. The reason for separating the applicator roll will be described.

As shown in FIG. 7, when the rotation directions of the cylindrical substrate 1 and the applicator roll 2 are set to the same direction, the ratio of the peripheral speed of the cylindrical substrate 1 to the peripheral speed of the applicator roll 2 on the work. The flow state of the paint differs depending on the ratio (= the peripheral speed of the cylindrical substrate 1 / the peripheral speed of the applicator roll 2). Generally, when the ratio is increased from a value smaller than 1 to a larger value, the flow state of the paint on the cylindrical substrate 1 shifts from a rippled state to a smooth surface, and when the ratio is further increased, it changes to a rib state. FIG. 9 shows an external view of this rib state. That is, the rib means a state in which the paint 5 is continuously uneven.

For a detailed description of the ribs, see "MODERN COATI
NG AND DRYING TECHNOLOGY (editorsEdward D. Cohen an
d Edgar B. Gutoff) p79-p103 "," Paint Flow and Film Form
(By Toshihiko Nakamichi, Gihodo Publishing) P84-P86 "etc.
To quote. Conventionally, the lower limit of rib generation is the number of capillaries
C_aAnd form parameter H₀/ R (H ₀: Cylindrical substrate 1 and
1/2 of the distance from the predicator roll 2, R: cylindrical substrate
(Radius of 1) has been variously discussed and reported.
The definition of this number of capillaries, and both at the critical point
Relationship is C_a= ΗU / γ (1) According to Pitts and Greiller, C_a= 31 (H₀/ R) (2) According to Mill and South C_a= 17.3 (H₀/ R)^3/4 (3) According to Greener et al. And Benkreira et al. C_a= 7500 (H₀/ R)^Two (4) C_a= 13.5 (H₀/ R)^2/3 Various reports (5) have been reported. Where η is the viscosity of the paint,
U is a representative speed (eg, peripheral speed of a cylindrical substrate), and
And γ indicate the surface tension of the paint. Therefore, the occurrence of ribs
Conditions are roll diameter, gap size, paint viscosity, surface
It is determined by the tension.
It is not uniquely determined.

The mechanism of the generation of the rib and the elimination of the seam when the roll is separated is as follows. In FIG. 7, most of the paint conveyed by the applicator roll 2 is transferred from the transfer starting point 91 to the transfer end point 92 via the outer peripheral surface of the cylindrical base 1 as the cylindrical base 1 rotates.
Reach At the transition starting point 91, a pressure gradient exists in the flow direction of the paint. Here, when a small disturbance of the pressure of the coating material 5 generated in the width direction of the cylindrical substrate 1 pulls the surface, the pressure profile remains almost the same but swells and shifts. A pressure gradient is created in the width direction of the cylindrical substrate 1 as shown by the arrow. This pressure gradient grows gradually and generates ribs. This state is shown in FIG. In the figure, the pressure on the coating film surface is atmospheric pressure (P1 = P3 = 0). The pressure inside the paint is as follows: P2 = P3−εdP / dX (6) Since dP / dX> 0, P2 <P1. Thus, this pressure gradient creates a rib. Generally, it is considered that the coating under the condition in which the rib is generated is not preferable. However, when applying the paint uniformly on the surface of the cylindrical substrate, it is a very effective method to obtain a uniform coating film after separating the cylindrical substrate and the applicator roll, not at the time of coating. The present inventors have found. This is the most important technical content of the present invention. Next, when the cylindrical substrate and the applicator roll are separated from each other, the pressure gradient caused by the ribs acts in the width direction as shown by the arrow in FIG. 10B, so that the seam which is a trace at the time of separation is leveled. It has the effect of getting lost. This leveling property is represented by Ln (A _t / A ₀ ) = − 16/3 · π ⁴ h ³ γ / λ ⁴ η according to the Orchard-Rhodes equation. Here, A _0, A _t the initial irregularity of the amplitude of the coated film after t time, lambda is the wavelength of the rib, h is the average film thickness. This equation shows that the change in the amplitude, that is, the leveling property, is affected by the powers of the factors related to the coating conditions, such as the rib wavelength and the film thickness, to the fourth and third powers. The paint factors are viscosity and surface tension. Therefore, it is desirable to exceed the limit number of capillaries of the ribs and to select a process condition for providing leveling properties and a coating property having high leveling properties. However, it is not easy to limit these conditions with a comprehensive range.

In order to quickly obtain the uniformity of the coating film formed on the outer periphery of the cylindrical substrate after the ribs are generated by setting the rotation direction of the cylindrical substrate and the rotation direction of the applicator roll in the same direction, the applicator roll is used. It is also important to make the film thickness of the paint supplied to the coating uniform. That is, after the cylindrical substrate starts contacting the paint on the outer peripheral surface of the applicator roll, 1
It is extremely difficult to form a uniform coating film on the outer peripheral surface of the cylindrical substrate by the degree of rotation, and a considerable number of rotations are required. However, since this speed affects production efficiency,
It is desirable to form a coating film having a uniform film thickness with the lowest possible number of rotations. In order to form a uniform coating film on the outer peripheral surface of the cylindrical substrate with a smaller number of rotations, it is effective to make the thickness of the coating film on the outer peripheral surface of the applicator roll uniform.
A method of making the thickness of the coating film on the outer peripheral surface of the applicator roll uniform will be described later. It is difficult to form a coating film quickly.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. 1 and 2 are a perspective view and a side view, respectively, showing a coating apparatus for carrying out the method of the present invention. 1 and 2, reference numeral 1 denotes a cylindrical substrate as an object to be coated, 2 denotes an applicator roll (coating roll), 3 denotes a metalling roll (film thickness control means), 4 denotes a cleaning doctor, and 5 denotes paint. .

The cylindrical base 1, the applicator roll 2, and the metering roll 3 are installed so as to be rotatable in the direction of the arrow by a rotating mechanism (not shown). Further, the cylindrical substrate 1
The applicator roll 2 and the applicator roll 2 are disposed close to each other with a gap capable of transferring the paint from the applicator roll 2 to the cylindrical substrate 1. They are arranged close to each other via a gap. The paint 5 is applied to the applicator roll 2 and the metering roll 3 by paint supply means (not shown).
And is stored in a paint storing section 51 formed by the cleaning doctor 4. In the present invention, proximity means
The state in which the cylindrical substrate and the application roll or the application roll and the film thickness control means are in contact with each other via the paint, and the separation means the state in which the close state has been released.

From the paint reservoir 51, the applicator roll 2
The paint 5 is supplied to the outer peripheral surface of the applicator roll 2 through the gap between the coating roll and the metalling roll 3,
The thickness of the paint supplied becomes uniform due to the presence of the metering roll 3. That is, by rotating the applicator roll 2 and the metering roll 3 in the direction of the arrow in this state, the film thickness of the paint 5 on the outer peripheral surface of the applicator roll 2 becomes uniform, so that the coating on the outer peripheral surface of the cylindrical substrate 1 is performed. The thickness of the paint to be applied quickly becomes uniform. In the above embodiment, the metering roll 3 is rotated, but may be fixed without rotating.

In the above embodiment, the metering roll 3
Is used to make the thickness of the paint 5 on the outer peripheral surface of the applicator roll 2 uniform, but as shown in FIG. 3, the applicator roll 2 is immersed in the paint 5 stored in the paint tank 52, As a control means, the gap setting doctor 6 is connected to the applicator roll 2 through a gap having a predetermined width.
May be arranged. In this state, the applicator roll 2
Is rotated, the thickness of the coating material 5 on the outer peripheral surface of the applicator roll 2 is made uniform.

Further, as shown in FIG. 4, a plate-shaped film thickness control means 61 is disposed in the tangential direction of the applicator roll 2 with a gap having a predetermined width, or provided on the outer periphery of a cylindrical body as shown in FIG. The film thickness control means 62 provided with a step may be disposed between the applicator roll 2 and a gap having a predetermined width. According to the film thickness control means 61 and 62 shown in FIGS. 4 and 5, the uniformity of the film thickness of the coating material 5 can be improved more than the gap setting doctor 6 shown in FIG.

As still another method, as shown in FIG. 6, a pickup roll 7 is placed in a paint 5 stored in a paint tank 52.
And the paint 5 transferred from the pick-up roll 7 to the applicator roll 2 is supplied through a gap between the applicator roll 2 and the metering roll 3 disposed close to the applicator roll 2. . In this case, the cleaning doctor 4 can be installed on the metering roll 3 to return the excess paint 5 to the paint tank 52. In this state, by rotating the applicator roll 2, the metering roll 3, and the pickup roll 7 in the direction of the arrow, the thickness of the paint on the outer peripheral surface of the applicator roll 2 is made uniform.

Although it has been described above that the cylindrical substrate and the applicator roll are in contact with each other via the paint, the specific gap width depends on the type of the paint to be applied and the cylindrical substrate. Depending on the film thickness finally formed,
The thickness may be set in the range of 0 μm to 1000 μm and a value equal to or less than the gap width between the applicator roll and the film thickness control means. The gap width between the applicator roll and the film thickness control means also depends on the type of paint to be applied and the film thickness finally formed on the cylindrical substrate.
What is necessary is just to set in the range of 0 micrometer-1000 micrometers.

The peripheral speed of rotation of the cylindrical substrate when the coating material is applied should be in the range of 3 m / min to 50 m / min, and the peripheral speed of rotation of the applicator roll should be 3 m / mi.
It is preferable to set the range of n to 50 m / min. If the peripheral speed of the cylindrical substrate and the applicator roll is low, the uniformity of the thickness of the coating film formed on the outer peripheral surface is insufficient. Conversely, if the peripheral speed is too high, the paint may be scattered by centrifugal force. Because there is.

The ratio of the peripheral speed of rotation of the cylindrical substrate to the peripheral speed of rotation of the applicator roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the applicator roll) is as described above when the CT paint is applied. Is preferably in the range of 2.0 to 15, and in the case of applying a CG paint, preferably in the range of 1.0 to 3.0, and in particular, in the case of applying a CT paint, 2.2 to 5.0.
Range, 1.5 to 1.5 when CG paint is applied
A range of 2.0 is more preferred. As described above, the rib generation conditions are determined by the viscosity, surface tension, peripheral speed, roll radius, and gap between the cylindrical substrate and the applicator roll. Here, if the morphological parameter is defined as 2 · (radius of cylindrical body) / (gap), and the number of capillaries = (viscosity) × (peripheral speed) / (surface tension), as the number of capillaries becomes smaller, the ribs become smaller. The range of occurrence is wider than the above range. As the number of capillaries increases, it approaches the above range. Also, the morphological parameter becomes closer to the above range as it increases, and becomes larger than the above range as it decreases. If the ratio of the diameter of the applicator roll to the diameter of the cylindrical substrate is in the range of 1/4 to 10, the present invention can be practiced without any problem.

In the coating method of the present invention, it is not preferable to apply one layer of paint to the outer peripheral surface of the cylindrical substrate, in other words, to separate from the applicator roll when the cylindrical substrate makes one rotation. That is, the coating material starts to be transferred from the applicator roll to the outer peripheral surface of the cylindrical substrate, and ribs are formed on the outer peripheral surface of the cylindrical substrate only after the cylindrical substrate rotates several times. Therefore, the cylindrical substrate is separated from the applicator roll while the ribs are formed on the coating film by rotating the cylindrical substrate several times. However, since the coating thickness of the coating material on the outer peripheral surface of the applicator roll is made uniform by the metalling roll, the rib can be generated with a small number of rotations.

After the cylindrical substrate was separated from the applicator roll, the rotation of the cylindrical substrate was continued by leveling and air-drying the formed coating film, and it was confirmed that no paint dripping would occur even if the rotation was stopped. And put it in a hot air circulating dryer to dry it completely.

In the case where a solvent having a relatively high volatility is used, a container or a shielding wall in which the applicator roll portion, the cylindrical base portion or the entire periphery thereof is substantially sealed to prevent drying due to the solvent volatilization. It is also effective to cover with such as.

As the material of the cylindrical substrate, for example, iron,
Metals such as aluminum, copper, manganese, silicon, magnesium, zinc, stainless steel, chromium, titanium, nickel, molybdenum, vanadium, indium, gold, platinum, or alloys of these, or resins such as polyester, or resins such as polyester, are made of conductive materials such as aluminum. Examples thereof include those that are deposited, but are not limited to those listed here.

When the cylindrical substrate is a photosensitive drum for electrophotography, the photosensitive layer to be formed is a single layer type in which the charge generating material and the charge transporting material are present in the same layer. It may be a stacked type in which a layer containing a charge generating material and a layer containing a charge transporting material are stacked.

The single-layer type photosensitive layer can be formed by applying a coating solution in which a charge generating material and a charge transporting material are dispersed or dissolved in a binder resin solution to the outer peripheral surface of a cylindrical substrate and then drying.

The laminate type photosensitive layer is formed by applying a coating material in which fine particles of a charge generating material are dispersed in a binder resin solution as needed to the outer peripheral surface of a cylindrical substrate and then drying to form a charge generating layer. Alternatively, it can be obtained by forming a charge transport layer by applying a coating solution in which a compound having a charge transport function is dissolved in a binder resin solution, followed by drying. Conversely, the charge generation layer may be formed after forming the charge transport layer on the outer peripheral surface of the cylindrical substrate.

In the case of a single-layer type electrophotographic photosensitive member, the thickness of the photosensitive layer in the electrophotographic photosensitive drum is 5 to 50.
The range of μm is preferred, and the range of 15 to 40 μm is particularly preferred.

In the case of a laminated electrophotographic photoreceptor, the thickness of the charge generation layer is preferably 5 μm or less.
The thickness is particularly preferably in the range of 1 to 1 μm, and the thickness of the charge transport layer is preferably in the range of 5 to 50 μm, and particularly preferably in the range of 15 to 40 μm.

Examples of the charge generating material include phthalocyanine pigments, azo pigments, quinone pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, quinacridone pigments, quinoline pigments, lakes Pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, azurenium dyes, squarium dyes, pyrylium dyes, triallylmethane dyes, xanthene dyes, thiazine dyes, cyanine dyes, etc. Examples include various organic pigments and dyes, and inorganic materials such as amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide, antimony sulfide, zinc oxide, and zinc sulfide.

The charge generating substance is not limited to those mentioned above, and can be used alone or in combination of two or more kinds. In the case of a charge generation layer formed by applying and drying a dispersion of fine particles of a charge generation material in a binder resin solution as needed, the ratio of the charge generation material to the binder resin is 10% by weight. : 1 to 1:10 is preferable, and a particularly preferable range is 6: 1 to 1: 2.

As the charge transporting material, a hole transporting material and / or an electron transporting material can be used. Examples of the hole transport material include low molecular weight compounds such as pyrene, carbazole, hydrazone, oxazole, oxadiazole, pyrazoline, arylamine, arylmethane, benzidine, thiazole, and stilbene. And butadiene compounds. Examples of the polymer compound include poly-N-vinyl carbazole, halogenated poly-N-vinyl carbazole, polyvinyl pyrene, polyvinyl anthracene, polyvinyl acridine, pyrene-formaldehyde resin, ethyl carbazole-formaldehyde resin, and ethyl carbazole. Formaldehyde resin, triphenylmethane polymer, polysilane and the like can be mentioned.

Examples of the electron transporting material include organic compounds such as benzoquinone, tetracyanoethylene, tetracyanoquinodimethane, fluorenone, xanthone, phenanthraquinone, phthalic anhydride and diphenoquinone. , Amorphous silicon, amorphous selenium, tellurium, selenium-tellurium alloy, cadmium sulfide,
Examples include inorganic materials such as antimony sulfide, zinc oxide, and zinc sulfide. The charge transporting material is not limited to those listed here, and can be used alone or as a mixture of two or more.

As the binder resin, it is preferable to use a high molecular polymer which is hydrophobic and can form an electrically insulating film. As such a high-molecular polymer, for example,
Polycarbonate, polyester, methacrylic resin, acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile polymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetic acid Vinyl-maleic anhydride copolymer, silicone resin, silicon-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, polyvinyl butyral, polyvinyl formal, polysulfone, and the like. It is not limited. These binder resins are used alone or in combination of two or more. Further, additives such as a plasticizer, a sensitizer, and a surface modifier can be used together with these binder resins.

Examples of the plasticizer include biphenyl, biphenyl chloride, o-terphenyl, dibutyl phthalate, diethylene glycol phthalate, dioctyl phthalate, triphenylphosphoric acid, methylnaphthalene, benzophenone, chlorinated paraffin, and various fluorohydrocarbons. .

Examples of the sensitizer include chloranil, tetracyanoethylene, methyl violet, rhodamine B, cyanine dye, merocyanine dye, pyrylium dye, and thiapyrylium dye.

Examples of the surface modifier include silicone oil, fluororesin and the like. In order to improve the adhesiveness between the cylindrical substrate and the photosensitive layer and to prevent the injection of free charges from the cylindrical substrate to the photosensitive layer, an adhesive layer may be interposed between the cylindrical substrate and the photosensitive layer, if necessary. Alternatively, a barrier layer (undercoat layer) can be provided.

Materials used for these layers include, in addition to the high molecular compound used for the binder, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, polyimide, carboxy-methyl cellulose, vinylidene chloride polymer latex, Polyurethane, aluminum oxide, tin oxide,
Titanium oxide and the like can be mentioned.

The substance imparting the function as an adhesive or a barrier is not limited to those listed here.
When used, they can be used alone or as a mixture of two or more.

When the adhesive layer or the barrier layer is provided, the thickness is preferably from 0.005 μm to 12 μm, and more preferably from 0.01 μm to 2 μm.

When the above-mentioned charge generating material and charge transporting material are dispersed and dissolved in a binder resin solution, the solvent for dissolving the binder may vary depending on the kind of the binder, but may not dissolve the underlying layer. Consider choosing from.

Specific examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol and benzyl alcohol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, isophorone and acetylacetone; N, N-dimethylformamide; , N
Amides such as dimethylacetamide; ethers such as tetrahydrofuran, dioxane, methyl cellosolve, and diglyme; esters such as methyl acetate, ethyl acetate, and diethyl carbonate; sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; methylene chloride, chloroform; Aliphatic halogenated hydrocarbons such as carbon tetrachloride, 1,1,2-trichloroethane; benzene, toluene, o-
Examples include, but are not limited to, aromatics such as xylene, p-xylene, m-xylene, monochlorobenzene, and dichlorobenzene. These solvents are used alone or in combination of two or more.

[0058]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the scope of these examples.

(Preparation until Application of Underlayer Coating Material) Hard Chrome Plating Surface Roughness 3.2 as Surface Treatment
S, an applicator roll 2 made of carbon steel having a length of 260 mm and an outer diameter of 65 mm, a metalling roll 3 having the same specifications, and a cylindrical substrate 1 to be coated were arranged as shown in FIG. The cylindrical substrate 1 is made of aluminum and has a length of 25 mm.
It has a hollow structure of 4 mm, an outer diameter of 30 mm, and a wall thickness of 1 mm. For the purpose of obtaining a photosensitive drum for electrophotography, an undercoating paint was first applied to the cylindrical substrate 1.

The undercoat paint is prepared by dissolving 3.5 parts of soluble nylon ("CM-8000" manufactured by Toray Industries, Inc.) in a mixed solvent consisting of 57.9 parts of ethanol and 38.6 parts of benzyl alcohol. did.

Both ends of the cylindrical substrate 1 are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward. This gripping mechanism is mounted on a moving device (not shown) that can approach and separate from the applicator roll 2. Although the cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, the moving device is set so that the gap width is 30 μm during coating. The gap width between the applicator roll 2 and the metering roll 3 was set to 50 μm from the beginning.

The rotation directions of the cylindrical substrate 1 and the applicator roll 2 are the same, and the rotation directions of the applicator roll 2 and the metering roll 3 are also the same. The peripheral speed is
20 m / min cylindrical base 1, applicator roll 2
Is 20 m / min, and the metering roll 3 is 10 m / mi.
n. Therefore, the ratio of the peripheral speed of the cylindrical substrate 1 to the peripheral speed of the applicator roll 2 (the cylindrical substrate 1
Peripheral speed / peripheral speed of the applicator roll 2) is 1.

After the applicator roll 2 and the metering roll 3 were rotated, the paint tank 7 containing the paint for the undercoat layer was raised by a lifting device (not shown), and the lower part of the applicator roll 2 was immersed. After rotating the applicator roll 2 and the metering roll 3, the paint formed by the cleaning doctor 4 close to both the rolls and the metering roll 3 is supplied, and a uniform thickness is applied to the outer peripheral surface of the applicator roll 2. A coating film for a pull layer was formed.

Thereafter, the cylindrical base 1 was rotated and brought close to the applicator roll 2 until the gap width was reached. As a result, the coating material on the applicator roll 2 was transferred to the cylindrical substrate 1 and application was started. After maintaining the rotating state for 3 seconds from the start of the transfer, the applicator roll 2
From the cylindrical substrate.

The cylindrical substrate 1 to which the undercoat layer was applied was air-dried while rotating it for 3 minutes, and then dried at 120 ° C. for 5 minutes by a hot-air circulation dryer.

The film thickness after drying was measured with a spectral reflection interference film thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 1.0 μm.

(Example 1) Cylindrical substrate 1 having an undercoat layer applied to the outer peripheral surface (hereinafter referred to as an undercoat layer-coated cylindrical substrate)
Was coated with a charge generation layer.

The paint for the charge generation layer was prepared by adding 0.5 part of α-oxytitanium phthalocyanine and 0.5 part of butyral resin (“ESREC BH-3” manufactured by Sekisui Chemical Co., Ltd.) to 49.5 parts of isopropyl alcohol and cyclohexanone. 4
Added to a mixed solvent consisting of 9.5 parts, an average particle size of 1.0 m
m glass beads were dispersed and mixed.

The undercoat layer-coated cylindrical substrate 1 to be coated is
Both ends are gripped by a gripping mechanism having a bearing that is connected to a rotation driving device (not shown) and that can rotate forward and backward.
This gripping mechanism is close to the applicator roll 2,
It is mounted on a moving device (not shown) that can be separated.

Although the undercoat layer-coated cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, the moving device is set so that the gap width is 30 μm at the time of coating. The applicator roll 2 and the metering roll 3
Was set to 45 μm from the beginning.

The rotation directions of the undercoat layer-coated cylindrical substrate 1 and the applicator roll 2 are the same, and the rotation directions of the applicator roll 2 and the metering roll 3 are also the same. The peripheral speed of the undercoat layer-coated cylindrical substrate 1 was 14.5.
m / min, applicator roll 2 is 10.1 m / mi
n, the metering roll 3 is 3 m / min.

After the applicator roll 2 and the metering roll 3 were rotated, the paint tank 7 containing the charge generating layer paint 5 was raised by a lifting device (not shown), and the lower part of the applicator roll 2 was immersed. . Applicator roll 2
And the coating formed by the cleaning doctor 4 close to the two metal rolls and the metalling roll 3 is supplied after the rotation of the metalling roll 3 and the coating material for the charge generating layer having a uniform thickness on the outer peripheral surface of the applicator roll 2. A coating was formed.

Thereafter, the cylindrical substrate 1 coated with the undercoat layer was brought close to the applicator roll 2 until the gap width was reached while rotating. As a result, the coating material on the applicator roll 2 was transferred to the cylindrical substrate 1 and application was started. When the rotating state was maintained for 3 seconds from the start of the transfer, it was confirmed that ribs were generated. Thereafter, the undercoat layer-coated cylindrical substrate 1 was separated from the applicator roll 2 from the applicator roll 2 with the ribs still formed.

When the undercoat layer cylindrical substrate 1 on which the charge generating layer was applied was rotated as it was, the ribs disappeared by leveling, and the substrate was air-dried while being further rotated for 3 minutes. Then, it dried at 120 degreeC for 5 minutes with the hot air circulation type dryer.

The film thickness after drying was measured by a spectral reflection interference film thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 0.2 μm.

Example 2 A charge transport layer was applied to a cylindrical substrate 1 having an outer peripheral surface coated with a charge generating layer (hereinafter referred to as a charge generating layer coated cylindrical substrate 1).

The coating material for the charge transport layer is composed of 20 parts of an arylamine compound represented by the chemical formula (1) and a polycarbonate resin ("Iupilon Z-20" manufactured by Mitsubishi Gas Chemical Company, Inc.).
0 ") was prepared by dissolving 25 parts in a mixed solvent consisting of 58 parts of cyclohexanone and 58 parts of xylene.

[0078]

Embedded image

As shown in FIG. 1, both ends of the cylindrical substrate 1 coated with the charge generating layer are gripped by a gripping mechanism having bearings that are connected to a rotation driving device (not shown) and that can rotate forward and reverse. This gripping mechanism is installed in a moving device (not shown) that can approach and separate from the applicator roll 2.

The charge generating layer coating cylindrical substrate 1 and the applicator roll 2 are initially separated from each other, but the moving device is set so that the gap width is 110 μm at the time of coating. The gap width between the applicator roll 2 and the metering roll 3 was set to 300 μm from the beginning.

The rotation directions of the cylindrical substrate 1 coated with the charge generation layer 1 and the applicator roll 2 are the same, and the rotation directions of the applicator roll 2 and the metering roll 3 are also the same. The peripheral speed of the cylindrical substrate 1 coated with the charge generation layer is 1
8.8 m / min, applicator roll 2 5.1 m / min
min, the metering roll is 1.0 m / min.

After the applicator roll 2 and the metering roll 3 were rotated, the paint tank 7 containing the charge transport layer paint 5 was raised by an elevator (not shown), and the lower part of the applicator roll 2 was immersed. . Applicator roll 2
And the coating formed by the cleaning doctor 4 adjacent to the two metal rolls and the metalling roll 3 is supplied after the rotation of the metalling roll 3 and the coating material for the charge transport layer having a uniform film thickness on the outer peripheral surface of the applicator roll 2. A coating was formed.

Thereafter, the cylindrical body 1 coated with the charge generating layer was brought close to the applicator roll 2 until the gap width was reached while rotating. This allows applicator roll 2
The above coating material was transferred to the charge generating layer coated cylindrical substrate 1 and coating was started. When the rotation state was maintained for 5 seconds from the start of the transfer, it was confirmed that ribs were generated. Thereafter, the charge generating layer-coated cylindrical substrate 1 was separated from the applicator roll 2 with the ribs still formed.

The charge-transporting-layer-coated cylindrical substrate 1 coated with the charge-transporting layer was air-dried while being rotated for 12 minutes, and then dried at 120 ° C. for 60 minutes by a hot-air circulation dryer.

The thickness of the film after drying was measured with a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Science Laboratory Co., Ltd.) and found to be 30.7 μm. In addition, the axial and circumferential film thickness distributions were measured. The results are shown in FIGS.

A printing test was carried out one day after the production using the electrophotographic photosensitive drum obtained as described above, and the image characteristics were good.

(Comparative Example 1) The coating was performed while the peripheral speed of the applicator roll 2 was fixed at 5.1 m / min while the peripheral speed of the charge generating layer coating cylindrical substrate 1 was changed to 5.1 m / min. It was applied under the same conditions and operation as in Example 2. After the coating was dried in the same manner as in Example 2, the film thickness distribution in the axial direction and the circumferential direction was measured. The results are shown in FIG. 11 and FIG. In this example, generation of ribs could not be observed.

Comparative Example 2 Cylindrical Substrate 1 Coated with Charge Generating Layer
Was applied under the same conditions and operations as in Example 2 except that the rotation direction of was set to the opposite direction to the rotation direction of the applicator roll 2. At this time, ribs were observed during application to the cylindrical substrate 1. After coating and drying in the same manner as in Example 2, the film thickness was measured. FIG. 13 shows the film thickness distribution in the circumferential direction.

11, 12, and 13, the cylindrical base 1 and the applicator roll 2 are rotated in the same direction, and the cylindrical base 1 is kept in a state in which the ribs are formed.
By separating the applicator roll 2 from the
A concave portion caused by a seam seen in Comparative Example 1;
It can be seen that a coating film having excellent film thickness uniformity can be formed without causing non-uniform film thickness due to the accumulation of paint observed in Comparative Example 2.

Example 3 While the peripheral speed of the applicator roll 2 was fixed at 10.2 m / min, the peripheral speed of the undercoat layer-coated cylindrical substrate 1 was changed to obtain a peripheral speed ratio (undercoat layer-coated cylinder). (The peripheral speed of the substrate 1 / the peripheral speed of the applicator roll 2) was changed to apply the coating for the charge generation layer, and the state of the obtained coating film surface was observed. The paint viscosity is 0.01 Pa · Sec, the diameter of the cylindrical substrate is 30 mmφ, the diameter of the application roll is 65 mmφ, and the distance between the cylindrical substrate and the application roll is 2 mm.
It was 50 μm. Others were applied under the same conditions and operation as in Example 1. Table 2 shows the results. When the peripheral speed ratio is low, seams are likely to occur, and when the peripheral speed ratio is high, the paint scatters from the cylindrical substrate 1. Therefore, a rib is generated at the time of application, and after the separation, in order to efficiently obtain a seamless and smooth coating film, the peripheral speed ratio is set to 1.0 to 3.0, more preferably 1.5 to 2.0. It is desirable to set.

[0091]

[Table 1]

(Example 4) By changing the peripheral speed of the charge-generating layer-coated cylindrical substrate 1 for fixing the peripheral speed of the applicator roll 2 to 5.1 m / min, the peripheral speed ratio (the charge-generating layer-coated cylindrical member) was changed. (Circumferential speed of substrate 1 / Circumferential speed of applicator roll 2)
Was changed to apply a paint for a charge transport layer, and the state of the obtained coating film surface was observed. The paint viscosity is 0.7Pa · Sec,
The diameter of the cylindrical substrate was 30 mmφ, the diameter of the application roll was 65 mmφ, and the interval between the cylindrical substrate and the application roll was 100 μm.
m. Others were applied under the same conditions and operation as in Example 2. Table 1 shows the results. When the peripheral speed ratio is low, seams are likely to occur, and when the peripheral speed ratio is high, the paint scatters from the cylindrical substrate 1. Therefore, ribs are generated at the time of coating, and after the separation, in order to efficiently obtain a seamless and smooth coating film, the peripheral speed ratio is 2.0 to 15, more preferably 2.2.
It is desired to set the value in the range of ~ 5.0.

[0093]

[Table 2]

[0094]

According to the present invention, an electrophotographic photosensitive drum having a photosensitive layer having a uniform coating film on the outer peripheral surface of a cylindrical substrate can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view showing an embodiment of the present invention.

FIG. 3 is a side view showing another embodiment of the present invention.

FIG. 4 is a side view showing another embodiment of the present invention.

FIG. 5 is a side view showing another embodiment of the present invention.

FIG. 6 is a side view showing another embodiment of the present invention.

FIG. 7 is a schematic diagram showing a case where a cylindrical substrate and an applicator roll are rotated in the same direction.

FIG. 8 is a schematic diagram showing a case where a cylindrical substrate and an applicator roll are rotated in opposite directions.

FIG. 9 is a perspective view showing an external view of a rib state.

FIG. 10 is a schematic diagram showing pressure directions when ribs are generated and disappear.

FIG. 11 is a graph showing a film thickness distribution in the axial direction of the electrophotographic photosensitive drum obtained in Example 2 and Comparative Example 1.

FIG. 12 is a graph showing a film thickness distribution in a circumferential direction of the electrophotographic photosensitive drum obtained in Example 2 and Comparative Example 1.

FIG. 13 is a graph showing a film thickness distribution in a circumferential direction of the electrophotographic photosensitive drum obtained in Comparative Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrophotographic photosensitive drum base (cylindrical base) 2 ... Applicator roll (coating roll) 5 ... Paint

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shoji Suzuki 2-8-35 Kurihara Kurihara, Saitama Prefecture Corp. Tone A202 F term (reference) 2H068 AA21 AA26 EA18 EA31 4D075 AC21 AC94 DA10 DB07 DC21

Claims (7)

[Claims] 1. A method of applying a coating material supplied to an application roll to a cylindrical substrate, the method comprising: applying the coating material to a cylindrical substrate; A method for applying a coating material to a cylindrical substrate, wherein the coating roller is separated from the cylindrical substrate while the ribs are formed on the film. 2. The method for applying paint to a cylindrical substrate according to claim 1, wherein the cylindrical substrate and the application roll rotate in the same direction in a non-contact state. . 3. The method of applying paint to a cylindrical substrate according to claim 1 or 2, wherein after applying the paint to the cylindrical substrate, the rotation is continued while the cylindrical substrate is separated from an application roll. Coating method on a cylindrical substrate. 4. A method of manufacturing a photosensitive drum for electrophotography, comprising applying a photosensitive coating material for electrophotography supplied to a coating roll to a photosensitive drum base for electrophotography and then drying the coating. The electronic device, wherein the roll is rotated in the same direction, and the coating roll is separated from the electrophotographic photosensitive drum base while the ribs are formed on the paint film on the electrophotographic photosensitive drum base. A method for producing a photoreceptor drum base. 5. The method of manufacturing a photosensitive drum base for electrophotography according to claim 4, wherein the photosensitive drum base for electrophotography and a coating roll rotate in the same direction in a non-contact state. For producing a photosensitive drum substrate for use. 6. The method for producing a photosensitive drum base for electrophotography according to claim 4 or 5, wherein when applying a coating material for a charge transport layer, the peripheral speed of the photosensitive drum base for electrophotography and the coating. A method of manufacturing a photosensitive drum base for electrophotography, wherein the ratio of the peripheral speed of the roll (the photosensitive drum base for electrophotography / the circumferential speed of the coating roll) is 2.0 to 15. 7. The method of manufacturing a photosensitive drum substrate for electrophotography according to claim 4, wherein when applying a coating material for a charge generation layer, the peripheral speed of the photosensitive drum substrate for electrophotography and the application. A method of manufacturing a photosensitive drum base for electrophotography, wherein a ratio of a peripheral speed of a roll (a photosensitive drum base for electrophotography / a peripheral speed of a coating roll) is 1.0 to 3.0.