JPH11235543A - Method and device for applying paint to cylindrical base material and production of electrophotographic photoreceptor drum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable effectively forming a uniform coating film on the outer peripheral surface of a cylindrical base material with simple control by rotating the cylindrical base material which is a material to be coated and rolls for applying paint to the cylindrical base material in the same direction in a noncontact state. SOLUTION: Paint 5 is fed to the outer peripheral surface of an applicator roll 2 through a gap between the applicator roll 2 and a metering roll 3 from a paint storage part 51. By passing the paint 5 through the gap of fixed width, the paint 5 fed to the outer peripheral surface of the applicator roll 2 is measured. By rotating the applicator roll 2 and the metering roll 3 in the same direction as that of the arrow in this state, the film thickness of the paint 5 on the outer peripheral surface of the applicator roll 2 can be uniformalized. Or an another method, the applicator roll 2 is immersed in the paint 5 in a paint tank, and also as a means for feeding the prescribed quantity of the paint, a gap setting doctor may be arranged on the applicator roll 2 through a gap of prescribed width.

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 a method for manufacturing a photosensitive drum for electrophotography.

[0002]

2. Description of the Related Art An electrophotographic photosensitive drum is provided with an undercoat layer, a charge generation layer, and a charge transport layer, which are sequentially coated and laminated on the outer peripheral surface of a hollow cylindrical base made of aluminum as an electrophotographic photosensitive body paint. In some cases, a photosensitive layer is formed.
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.

The blade coating method is a coating method in which a blade is arranged at a position facing 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 an aluminum substrate for a photosensitive drum for electrophotography is rotated as a cylindrical substrate, a rotational deviation of about 50 μm may occur depending on the accuracy of the cylindrical substrate itself and the accuracy of the rotation driving unit. On the other hand, when the electrophotographic photoreceptor coating is composed of an undercoat layer, a charge generation layer, and a charge transport layer, the thickness of the thinnest charge generation layer is sub-μm and the thickness of the thickest charge transport layer is 20 to 50 μm Because
An essential problem has been pointed out as to whether a coating film having a uniform film thickness can be formed in the state where the rotational blur occurs.

[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 In view of the above situation, the present inventors have made intensive studies on the roll coating method, and found that a cylindrical substrate as an object to be coated and a roll for applying a coating material to the cylindrical substrate were not used. It has been found that the uniformity of the coating film formed on the cylindrical substrate can be improved by rotating in the same direction in the contact state. And, in order to further improve the uniformity of the coating film, to make the coating film thickness on the application roll uniform,
It has also been found that it is important to set 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) to a predetermined value.

The present invention is based on the above findings,
A method for applying a coating material to a cylindrical substrate, wherein the coating material supplied to the application roll is applied to the cylindrical substrate, wherein the coating is performed while rotating the cylindrical substrate and the application roll in the same direction in a non-contact state. . In the present invention, the thickness of the coating material supplied to the application roll is made uniform, and the ratio of the peripheral speed of the cylindrical substrate to the peripheral speed of the application roll (the peripheral speed of the cylindrical substrate /
The peripheral speed of the application roll is preferably in the range of 0.5 to 2.0. Further, in the present invention, it is more preferable that, after applying the coating material to the cylindrical substrate, the rotation is continued while the cylindrical substrate is separated from the application roll.

In the coating method of the present invention, a cylindrical substrate and an application roll are disposed in close proximity to each other, and the coating material supplied to the application roll is applied to the cylindrical substrate. A coating roll that rotates in the same direction as the rotation of the cylindrical substrate in a non-contact state when applying a coating material to the cylindrical substrate, and coating the coating onto the cylindrical substrate having a film thickness control means disposed close to the coating roll It can be performed by an apparatus. In the above-described coating apparatus, a cylindrical member or a plate member can be used as the film thickness control means.

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. A method for producing a photosensitive drum for electrophotography, wherein the photosensitive drum base for electrophotography is applied to the photosensitive drum base for electrophotography while rotating the body drum base and the application roll in the same rotational direction in a non-contact state. Is provided. In this method of manufacturing an electrophotographic photosensitive drum,
The film thickness of the electrophotographic photosensitive drum paint supplied to the coating roll is made uniform, and the ratio of the peripheral speed of the electrophotographic photosensitive drum substrate to the peripheral speed of the coating roll (the peripheral speed of the electrophotographic photosensitive drum substrate) Speed / peripheral speed of the coating roll) is preferably in the range of 0.5 to 2.0.

In the present invention, the non-contact state means that the cylindrical substrate (photosensitive drum for electrophotography) is not in direct contact with the coating roll, or a member such as a spacer to be described later. Refers to a state in which they are not in contact with each other. For example, this corresponds to a state in which the cylindrical substrate (photoconductor drum substrate for electrophotography) and the application roll are not in direct contact with each other but are in contact via the paint. Further, in the present invention, a state in which the cylindrical substrate (photoconductor drum substrate for electrophotography) and the application roll are in contact with each other via the paint is referred to as proximity, and when this state is released, separation is referred to as separation. I do.

Hereinafter, a method and an apparatus for coating 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 is shown in FIGS.
It will be described based on.

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 in a non-contact state, and FIG. 8 shows a case where the cylindrical base 1 and the applicator roll 2 are opposite in a non-contact state. It shows the case of rotating in the direction. Reference numeral 5 denotes a paint, which is transferred from the applicator roll 2 to the cylindrical substrate 1 and applied. 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).

As shown in FIG. 8, when the cylindrical substrate 1 and the applicator roll 2 rotate in opposite directions, 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, a portion corresponding to the paint pool 8 protrudes and impairs the uniformity of the coating 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 base 1 and the applicator roll 2 is set to the same direction, the paint accumulation does not occur, or even if it occurs, the amount is small. That is, most of the paint conveyed by the applicator roll 2 reaches the transfer end point 92 from the arrow (chain line) transfer start 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. A small amount, if any, is generated and the applicator roll 2
The leveling after the separation of the cylindrical substrate 1 from the substrate can be resolved to such an extent that the function is not hindered.

In the present invention, when the paint is applied, the cylindrical substrate 1 and the applicator roll 2 are not in contact with each other, but this is caused by the gap formed between the cylindrical substrate 1 and the applicator roll 2. Has the following significance in addition to that required for the paint to pass through. That is, for example, it is conceivable to make the coating film thickness uniform by using a spacer for keeping the gap value between the cylindrical substrate 1 and the applicator roll 2 constant. In practice, a gap of about 50 μm occurs due to the precision and the precision of the rotation driving means, so that the gap value cannot be kept constant in reality, and rather, the smooth rotation of the cylindrical base body 1 and the applicator roll 2 is hindered. The uniformity of the film may be adversely affected. However, as in the present invention, the cylindrical substrate 1
Such a problem does not occur if the roller and the applicator roll 2 are in a non-contact state, and the cylindrical base 1 and the applicator roll 2 are rotated in the same direction in spite of rotational shake. In addition, the uniformity of the coating film can be improved.

By making the rotation direction of the cylindrical substrate and the applicator roll in the same direction, it is possible to prevent or suppress the generation of the paint pool, but it is possible to quickly improve the uniformity of the coating film formed on the outer periphery of the cylindrical substrate. It is important to make the thickness of the paint supplied to the applicator roll uniform in order to obtain a uniform thickness. That is, it is extremely difficult to form a uniform coating film on the outer peripheral surface of the cylindrical substrate only by one rotation after the cylindrical substrate starts contacting with the paint on the outer peripheral surface of the applicator roll. is necessary. However, since the number of rotations affects the production efficiency, it is desirable to form a coating film having a uniform thickness with the minimum 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 for making the thickness of the coating film on the outer peripheral surface of the applicator roll uniform will be described later, but only by immersing the applicator roll in the coating and adhering the coating on the outer peripheral surface, the uniformity of the cylindrical substrate is obtained. It is difficult to form a coating film quickly. In the initial stage of coating, the thickness of the coating on the outer periphery of the applicator roll is set to be larger than the thickness of the coating to be formed on the cylindrical substrate at the time of coating, and thereafter, a uniform coating is rapidly formed. It is effective to do.

Next, it is desirable that the ratio of the peripheral speed of the cylindrical substrate to the applicator roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the applicator roll) be in the range of 0.5 to 2.0. Will be described. If the ratio of the peripheral speed between the cylindrical substrate and the applicator roll is too small, a paint pool tends to be formed at the transition starting point even if the rotation directions of the cylindrical substrate and the applicator roll are the same, Streaky unevenness occurs in the formed coating film. Conversely, if the ratio between the peripheral speed of the cylindrical substrate and the peripheral speed of the applicator roll is too large, a paint pool tends to be formed at the transition end point, and the coating formed on the cylindrical substrate will have a stripe-shaped unevenness. From the above, in the present invention, the ratio of the peripheral speed of the cylindrical substrate and the applicator roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the applicator roll)
Is preferably in the range of 0.5 to 2.0, more preferably 0.6 to 1.5.

[0026]

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 one embodiment 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 metering roll (film thickness control means), 4
Is a cleaning doctor, and 5 is a 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
And the applicator roll 2 are arranged with a gap capable of transferring the paint from the applicator roll 2 to the cylindrical substrate 1, and the applicator roll 2 and the metering roll 3 have a gap which is capable of storing the paint 5. Are arranged through. The paint 5 is stored in a paint storage unit 51 formed by the applicator roll 2, the metering roll 3, and the cleaning doctor 4 by a paint supply unit (not shown).

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 coating material 5 supplied to the outer peripheral surface of the applicator roll 2 is measured by passing the coating material 5 through the gap having a predetermined width. By rotating the applicator roll 2 and the metering roll 3 in the direction of the arrow in this state, the thickness of the paint 5 on the outer peripheral surface of the applicator roll 2 becomes uniform,
The thickness of the coating applied to the outer peripheral surface of the cylindrical substrate 1 also becomes uniform quickly. 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, The doctor 6 for setting the gap may be disposed on the applicator roll 2 via a gap having a predetermined width as a means for supplying the paint. In this state,
By rotating the applicator roll 2, 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 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 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 coating 5 transferred from the pick-up roll 7 to the applicator roll 2 is measured and supplied through a gap between the applicator roll 2 and the metering roll 3 disposed close to the applicator roll 2. is there. In this case, the cleaning doctor 4 can be disposed close to the metering roll 3 so that excess paint 5 can be returned to the paint tank 52. In this state, the applicator roll 2 and the metering roll 3
By rotating 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 through the paint, the specific gap width depends on the type of the paint to be applied and the cylindrical substrate. The thickness may be set in the range of 10 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, depending on the film thickness finally formed after drying. Further, the gap width between the applicator roll and the film thickness control means may be set in the range of 10 μm to 1000 μm depending on the type of paint to be applied and the film thickness finally formed on the cylindrical substrate.

In particular, when manufacturing an electrophotographic photosensitive drum, the gap width between the electrophotographic photosensitive drum base and the application roll is in the range of 10 to 300 μm, and the electrophotographic photosensitive drum is applied during coating. It is preferable that the gap width is in the range from the same as the film thickness formed on the body drum base to three times, and it is more preferable that the gap width be equal to or less than the gap width between the application roll and the film thickness control means. .

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 / min to 50 m / min.
It is preferably in the range of 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 0.5 to 2.0 as described above. Is preferable, and the range of 0.6 to 1.5 is more preferable. 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 the coating film made of the paint is uniformly 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 after the cylindrical substrate is rotated several times to form a uniform coating film. However, in the present invention, since the coating film of the paint on the outer peripheral surface of the applicator roll is made uniform, the coating film thickness on the outer peripheral surface of the cylindrical substrate can be made uniform 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, and 0.01 to 1 μm.
μm is particularly preferable, and the thickness of the charge transport layer is 5 to 5 μm.
A range of 0 μm is preferred, and a range of 15 to 40 μm is particularly preferred.

Examples of the charge generation 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 as a mixture 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.

As the surface modifier, for example, silicone oil, fluororesin and the like can be mentioned. 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.

The materials used for these layers include, in addition to the polymer compound used for the binder, casein, gelatin, polyvinyl alcohol, ethyl cellulose, phenol resin, polyamide, polyimide, carboxy-methyl cellulose, vinylidene chloride-based 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 be one among those which do 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.

[0057]

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. (Example 1) An applicator roll 2 made of carbon steel having a surface roughness of 3.2S, a length of 260 mm, and an outer diameter of 65 mm, and a metalling roll 3 of the same specifications, and a work to be coated. And the cylindrical substrate 1 as shown in FIG. The cylindrical substrate 1 is made of aluminum and has a hollow structure with a length of 254 mm, an outer diameter of 30 mm, and a wall thickness of 1 mm. For the purpose of obtaining a photosensitive drum for electrophotography, a coating for an undercoat layer was first applied to the cylindrical substrate 1.

The coating for the undercoat layer 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 substrate, 2 applicator rolls
0 m / min and the metering roll were set to 10 m / min. Therefore, 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 1.

After rotating the applicator roll 2 and the metering roll 3, 5 g of the undercoat layer paint is supplied to the paint storage section 51 formed by the cleaning doctor 4 in contact with both rolls and the metering roll. Then, a coating film having a uniform film thickness was formed on the outer peripheral surface of the applicator roll 2.

Thereafter, the cylindrical substrate 1 was brought close to the applicator roll 2 while rotating until the above-mentioned 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 by a spectral reflection interference film thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 1.0 μm. The thickness of the paint for the undercoat layer during application of the paint is 28.6 μm when calculated from the thickness of the paint after drying and the paint components.

(Example 2) The coating apparatus used in Example 1 was applied to the cylindrical substrate 1 in which the outer layer was coated on the outer peripheral surface in Example 1 (hereinafter referred to as an undercoat layer-coated cylindrical substrate). hand,
A charge generation layer was applied.

The coating for the charge generation layer was 0.8 parts of α-type oxytitanium phthalocyanine and 0.8 parts of butyral resin (“ESLEC BH-3” manufactured by Sekisui Chemical Co., Ltd.), 49.25 parts of isopropyl alcohol and cyclohexanone. It was added to a mixed solvent consisting of 49.25 parts, and the average particle size was 1.
It was prepared by dispersing and mixing with 0 mm glass beads.

An undercoat layer-coated cylindrical substrate 1 to be coated
As in the first embodiment, 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 mounted on a moving device (not shown) that can approach and separate from the applicator roll 2.

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 11.2.
m / min, applicator roll 2 is 10.1 m / mi
n, the metering roll is 5 m / min.

After rotating the applicator roll 2 and the metering roll 3, 5 g of the above-mentioned charge generating layer paint is stored in the paint reservoir 51 formed by the cleaning doctor 4 in contact with both rolls and the metering roll 3. Supply,
A coating film having a uniform thickness was formed on the outer peripheral surface of the applicator roll 2.

Thereafter, the cylindrical substrate 1 coated with the undercoat layer 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 cylindrical substrate 1 coated with the undercoat layer was separated from the applicator roll 2.

The undercoat layer cylindrical substrate 1 on which the charge generation 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 thickness of the dried charge generating layer was measured by a spectral reflection interference thickness meter (“TFM-120” manufactured by Oak Manufacturing Co., Ltd.) and found to be 0.2 μm. The thickness of the paint for the charge generation layer during application of the paint is 12.5 μm when calculated from the dried film thickness and the paint components.

(Example 3) The coating apparatus used in Examples 1 and 2 for the cylindrical substrate 1 having the charge generating layer applied to the outer peripheral surface thereof in Example 2 (hereinafter referred to as the charge generating layer coated cylindrical substrate 1). Was used to apply the charge transport layer.

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.

[0076]

Embedded image

The charge-generating layer-coated cylindrical substrate 1 was prepared in Example 1.
Similarly, 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 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 becomes 100 μm at the time of coating. The gap width between the applicator roll 2 and the metering roll 3 was set to 200 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
0.2 m / min, applicator roll 2 is 10.2 m
/ Min, and the metering roll is 2 m / min.

After rotating the applicator roll 2 and the metering roll 3, 10 g of the charge transport layer paint is stored in the paint storage section 51 formed by the cleaning doctor 4 in contact with both rolls and the metering roll 3. Then, a coating film having a uniform thickness was formed on the outer peripheral surface of the applicator roll 2.

Thereafter, the cylindrical body 1 coated with the charge generating layer was rotated and brought close to the applicator roll 2 until the gap width was reached. This allows applicator roll 2
The above coating material was transferred to the charge generating layer coated cylindrical substrate 1 and coating was started. After maintaining the rotating state for 5 seconds from the start of the transfer, the charge generating layer-coated cylindrical substrate 1 was separated from the applicator roll 2.

The charge-generating 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 dried charge transport layer was measured by a high-frequency eddy current film thickness meter (“LH-300C” manufactured by Kett Scientific Research Institute) and found to be 27.0 μm. FIG. 9 shows the film thickness distribution in the axial direction, and FIG. 10 shows the film thickness distribution in the circumferential direction. The thickness of the paint for the charge transport layer during application of the paint is 100 μm when calculated from the dried film thickness and the paint components.

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

(Example 4) The undercoat layer-coated cylindrical substrate 1 obtained in Example 1 was coated with the coating material for the charge generation layer used in Example 2 at a peripheral speed of the applicator roll 2 of 10.1 m / m. mi
By changing the peripheral speed of the undercoat layer-applied cylindrical substrate 1 while fixing it at n, the peripheral speed ratio (the peripheral speed of the undercoat layer-applied cylindrical substrate 1 / the peripheral speed of the applicator roll 2) is changed. Except for the above, the coating was performed under the same conditions and operation as in Example 2. The state of the obtained coating film surface was observed. The results are shown in Table 1. When the peripheral speed ratio is low or high, it is difficult to obtain a smooth coating film, and in order to efficiently obtain a smooth coating film, the peripheral speed ratio is 0.5 to 2.0, More preferably, it is desired to set the range of 0.6 to 1.5.

[0085]

[Table 1]

Comparative Example 1 An applicator roll 2 was rotatably immersed in a coating tank as shown in FIG. 3 in the cylindrical substrate 1 coated with the charge generating layer obtained in Example 2. And the same charge transport layer as that described above. However, here, in order to obtain a coating film having a thickness equivalent to the thickness of the charge transport layer of Example 3 without using the film thickness control means, the specific composition of the paint, the charge generation layer coated cylindrical substrate 1 and The rotation speed of the applicator roll 2 was adjusted. After coating and drying in the same manner as in Example 3, the film thickness was measured. FIG. 9 shows the film thickness distribution in the axial direction, and FIG. 10 shows the film thickness distribution in the circumferential direction.

9 and 10, the applicator roll 2
It can be seen that the uniformity of the coating thickness on the outer peripheral surface improves the uniformity of the coating thickness formed on the outer peripheral surface of the cylindrical substrate 1.

When a printing test was performed one day after the preparation using the electrophotographic photosensitive drum obtained in Comparative Example 1, the printed image was uneven.

(Comparative Example 2) When applying the coating material for the charge generation layer used in Example 2 to the cylindrical substrate 1 coated with the undercoat layer obtained in Example 1, the cylindrical substrate 1 coated with the undercoat layer was The rotation direction with the applicator roll 2 is set to the opposite direction, and the peripheral speed is set at 11.2 m / min for the undercoat layer-coated cylindrical substrate, 10.1 m / min for the applicator roll, and 5.0 m / min for the metering roll. The operation was performed under the same conditions and operation as in Example 2 except that the settings were made as follows. As a result, since the undercoat layer-coated cylindrical substrate 1 is separated from the applicator roll 2, the excess charge generation layer paint accumulated in the paint pool 8 is spread by the leveling action.
The undercoat layer was not uniformly spread over the entire outer peripheral surface of the cylindrical substrate, but was fixed as a band-like portion having a dark color.
Even if an electron transport layer is applied to obtain a photosensitive drum for electrophotography, this part has clearly different electrical characteristics from other parts,
It could not be used because it affects the printed image.

Comparative Example 3 A charge transport coating was applied under the same conditions and operations as in Example 3, except that the rotation direction of the charge generating layer-coated cylindrical substrate 1 and the applicator roll 2 was reversed. However, during application, many streaks (streaks) due to the paint were generated in both the applicator roll 2 and the charge-generating layer-coated cylindrical substrate 1 in the circumferential direction. This streak was slightly eliminated by leveling after separating the charge generating layer-coated cylindrical substrate 1 from the applicator roll 2. Even after air-drying, the paint dripped from that part.

[0091]

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 graph showing the axial film thickness distribution of the electrophotographic photosensitive drum obtained in Example 3 and Comparative Example 1.

FIG. 10 is a graph showing the film thickness distribution in the circumferential direction of the electrophotographic photosensitive drum obtained in Example 3 and Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylindrical base material 2 ... Applicator roll (coating roll) 3 ... Metalling roll (film thickness control means) 4 ... Cleaning doctor 5 ... Paint 6 ... Gap setting doctor (Thickness control means) 7: Pickup roll 8: Paint pool

Claims (11)

[Claims] 1. A coating method for coating a cylindrical substrate with a coating material supplied to a coating roll, wherein the coating is applied while rotating the cylindrical substrate and the coating roll in the same direction in a non-contact state. A method for applying a paint to a cylindrical substrate, characterized in that it is characterized in that: 2. The method for applying a coating to a cylindrical substrate according to claim 1, wherein the coating is applied while making the thickness of the coating supplied to the coating roll uniform. 3. The ratio of the peripheral speed of the cylindrical substrate to the peripheral speed of the application roll (the peripheral speed of the cylindrical substrate / the peripheral speed of the application roll) is 0.5 to 0.5.
3. The method according to claim 1, wherein said coating material has a range of 2.0. 4. The coating method according to claim 1, wherein after the coating of the coating on the cylindrical substrate, the rotation is continued while the cylindrical substrate is separated from the coating roll. 5. A coating apparatus for coating a cylindrical substrate, wherein a cylindrical substrate and an application roll are disposed close to each other, and a coating material supplied to the application roll is applied to the cylindrical substrate. A coating roll that rotates in the same direction as the rotation of the cylindrical substrate in a non-contact state, and a film thickness control unit disposed in close proximity to the coating roll. 6. The coating apparatus for coating a cylindrical substrate according to claim 5, wherein the film thickness control means comprises a cylindrical member. 7. The coating device for coating a cylindrical substrate according to claim 5, wherein the film thickness control means comprises a plate-like member. 8. A method for manufacturing a photosensitive drum for electrophotography, comprising applying the photosensitive coating material for electrophotography supplied to a coating roll to a photosensitive drum base for electrophotography and then drying the coating. A method for manufacturing a photosensitive drum for electrophotography, comprising applying a coating material for a photosensitive drum for electrophotography to a base of a photosensitive drum for electrophotography while rotating a roll in the same rotational direction in a non-contact state. 9. The method of manufacturing an electrophotographic photosensitive drum according to claim 8, wherein the paint is applied while the film thickness of the electrophotographic photosensitive material supplied to the application roll is made uniform. 10. The ratio of the peripheral speed of the electrophotographic photosensitive drum substrate to the peripheral speed of the coating roll (the peripheral speed of the electrophotographic photosensitive drum substrate / the peripheral speed of the application roll) is 0.5 to 2.0. The method for manufacturing a photosensitive drum for electrophotography according to claim 8, wherein the range is a range. 11. The method for producing an electrophotographic photosensitive drum according to claim 8, wherein a gap width between the electrophotographic photosensitive drum substrate and the application roll is in a range of 10 to 300 μm.