JP5787592B2 - Method for manufacturing roller member - Google Patents

Description

  The present invention relates to a method for manufacturing a roller member.

In recent years, an electrophotographic image forming apparatus such as a printer has been improved in image quality. Accordingly, various roller members such as a developing roller, a transfer roller, and a fixing roller used in the image forming apparatus are required to have high accuracy and high durability.
A surface layer such as a crosslinkable resin coating layer is often formed on the roller member. Since the surface layer has a great influence on image characteristics, a high degree of film uniformity is required. Therefore, it is very important to form a uniform film in the coating process.
The conventional coating method using a ring coating head is a method in which a ring coating head and a roller member are relatively moved while discharging a constant amount of coating liquid from the slit-shaped discharge part of the ring coating head that is opened all around the circumference. By moving it, it is possible to apply the thin film layer at high speed. Further, by controlling the discharge amount and the moving speed, there are advantages that the film thickness control is easy and the coating efficiency is high.
However, depending on the type of paint or surface treatment agent (viscosity, etc.) and application conditions (application method, application speed, etc.), a non-uniform film is often formed due to uneven application, dripping, or running out of liquid. There is.
Regarding the uneven application in the circumferential direction, Patent Document 1 discloses that a feature is provided in the structure in the ring application head in order to make the discharge amount from the slit-like discharge port provided in the ring application head uniform. Patent Document 2 discloses that a roller is rotated during coating.

JP-A-10-156256 JP 2003-190870 A

In a roller member that needs to obtain a uniform nip with an object to be charged such as a contact-type charging roller, the roller has a shape that becomes the largest at the central portion and gradually decreases toward the end (hereinafter referred to as a crown shape). Generally, a difference in outer diameter is provided in the longitudinal direction of the roller.
For such a roller whose outer diameter changes, the gap between the ring application head and the outer periphery of the roller changes in the coating process, so that application unevenness and dripping are particularly likely to occur. Therefore, it is a problem to uniformly coat even a roller having a large outer diameter change.

A shaft body that is supported in the vertical direction and has an outer diameter that varies in the axial direction; a ring coating head that surrounds the entire outer peripheral surface of the shaft body and is disposed at a predetermined distance from the central axis of the shaft body; Is a method of manufacturing a roller member having a step of forming a coating film on the outer peripheral surface of the shaft body by discharging a coating liquid from the discharge port of the ring coating head while relatively moving the shaft in the axial direction. And
The ring application head has an inner diameter variable member capable of changing an inner diameter below the discharge port ,
The process, to also maintain the difference between the outer diameter of the inner diameter and the shaft of the inner diameter of the variable member substantially constant while relatively moving the said shaft body and the ring coating head in axial direction And a step of changing the inner diameter of the inner diameter variable member in accordance with the outer diameter of the shaft body .

As described above, according to the present invention, a roller that is uniform in the circumferential direction can be manufactured even with respect to a roller whose outer diameter changes in the longitudinal direction.

It is sectional drawing of a roller member (charging roller). It is the schematic which shows an example of the ring application | coating head which concerns on this invention. Schematic which shows the other example of the ring application | coating head which concerns on this invention. Schematic which shows an example of the conventional ring application head. Schematic for demonstrating the R surface process performed with respect to the rubber both ends of a roller member. Schematic for demonstrating the C surface process performed with respect to the rubber both ends of a roller member. FIG. 3 is a partially enlarged sectional view of the ring application head shown in FIG. 2.

Hereinafter, the present invention will be described in more detail with an example of a charging roller. However, the present invention is not limited to this.
A cross-sectional view of a specific configuration of the charging roller is shown in FIG. Here, (a) shows a transverse section of the charging roller, and (b) shows a longitudinal section.
The charging roller includes a conductive support 1, a conductive elastic layer 2 formed on the outer periphery thereof, and an outermost layer 3 that covers the outer periphery of the conductive elastic layer 2. Hereinafter, unless otherwise specified, the conductive support and the conductive elastic layer are collectively referred to as “conductive base layer roller”.

<Conductive support>
The material of the conductive support 1 used in the present invention may be conductive. Examples of specific materials include metals such as iron, aluminum, titanium, copper and nickel; alloys such as stainless steel, duralumin, brass and bronze containing these metals; composite materials in which carbon black and carbon fibers are consolidated with plastic Etc.

<Conductive elastic layer>
The conductive elastic layer 2 formed on the outer periphery of the conductive support 1 is usually formed by mixing a conductive agent and a polymer elastic body. The following can be used as the polymer elastic body. Epichlorohydrin rubber, NBR (nitrile rubber), CR (chloroprene rubber), urethane rubber, silicone rubber, SBS (styrene-butadiene-styrene-block copolymer), SEBS (styrene-ethylenebutylene-styrene-block copolymer) Such thermoplastic elastomer. As the polymer elastic body, epichlorohydrin rubber is particularly suitable. In the epichlorohydrin rubber, the polymer itself has conductivity in the middle resistance region, and can exhibit good conductivity even if the amount of the conductive agent added is small. Moreover, since the variation in electrical resistance depending on the position can be reduced, it is suitable as a polymer elastic body. In addition, the following are mentioned as epichlorohydrin rubber. Epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-allyl glycidyl ether copolymer and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer. Among these, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer is particularly preferable because it exhibits stable conductivity in a medium resistance region. The epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer can control conductivity and workability by arbitrarily adjusting the degree of polymerization and composition ratio.

  The polymer elastic body is mainly composed of epichlorohydrin rubber, but may contain other general rubbers and elastomers as necessary. As other general rubbers and elastomers, the following can be used. EPM (ethylene / propylene rubber), EPDM (ethylene / propylene / diene rubber), NBR (nitrile rubber), chloroprene rubber, natural rubber, IR (isoprene rubber), BR (butadiene rubber), SBR (styrene-butadiene rubber), urethane Rubber, silicone rubber. A thermoplastic elastomer such as SBS (styrene / butadiene / styrene block copolymer) or SEBS (styrene / ethylene butylene / styrene block copolymer) may be used. In addition, when these general rubber | gum and elastomer are contained, it is preferable that the content is 1 to 50 mass% with respect to the polymer elastic body whole quantity.

<Conductive agent>
As the conductive agent, an ionic conductive agent or an electronic conductive agent can be used. For the purpose of reducing unevenness in electrical resistivity of the conductive elastic layer, it is preferable to contain an ionic conductive agent. By uniformly dispersing the ionic conductive agent in the polymer elastic body and making the electric resistance of the conductive elastic layer uniform, uniform charging can be obtained even when the charging roller is used only by applying a DC voltage. it can.

<Ionic conductive agent>
The ionic conductive agent is not particularly limited as long as it is an ionic conductive agent exhibiting ionic conductivity. The following are mentioned as an ionic conductive agent. Inorganic ionic substances such as lithium perchlorate, sodium perchlorate, calcium perchlorate; lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, octadecyltrimethylammonium chloride, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, trioctylpropylammonium Cationic surfactants such as bromide and modified aliphatic dimethylethylammonium ethosulphate; amphoteric surfactants such as laurylbetaine and dimethylalkyllaurylbetaine; tetraethylammonium perchlorate, tetrabutylammonium perchlorate, perchloric acid Perchloric acid quaternary ammonium salts such as trimethyloctadecyl ammonium; trifluoromethanesulfuric acid Organic acids such as lithium salt of lithium phosphate. These can be used alone or in combination of two or more. Among ionic conductive agents, quaternary ammonium perchlorate is particularly preferably used because of its resistance to environmental changes.

<Electronic conductive agent>
The electronic conductive agent is not particularly limited as long as it is an electronic conductive agent exhibiting electronic conductivity. Examples of the electronic conductive agent include the following. Metal-based powders and fibers such as aluminum, palladium, iron, copper and silver; metal oxides such as titanium oxide, tin oxide and zinc oxide; tin oxide, antimony oxide, indium oxide and molybdenum oxide on the surface of suitable particles , Zinc, aluminum, gold, silver, copper, iron, platinum, or rhodium powder deposited by electrolytic treatment, spray coating, mixed shaking; furnace black, thermal black, acetylene black, ketjen black, PAN ( Carbon powder such as polyacrylonitrile) pitch carbon.

  Moreover, these electrically conductive agents can be used individually or in combination of 2 or more types.

In addition to this, the conductive elastic layer 2 may contain a compounding agent such as a plasticizer, a filler, a vulcanizing agent, a vulcanization accelerator, an anti-aging agent, an anti-scorch agent, a dispersing agent, and a release agent as necessary. It can also be added.
As a method for forming the conductive elastic layer 2, it is preferable to mix the raw materials of the conductive elastic layer 2 with a closed mixer and to form the conductive elastic layer 2 by a known method such as extrusion molding, injection molding, or compression molding. . In addition, the conductive elastic layer may be directly molded on the conductive support 1, or the conductive elastic layer 2 previously formed into a tube shape may be coated on the conductive support 1. In addition, it is also preferable that the surface is polished and the shape is adjusted after the production of the conductive elastic layer 2.

<Shape of conductive elastic layer>
The shape of the conductive elastic layer 2 is preferably a crown shape that is thickest at the center and narrows toward both ends in order to ensure uniform adhesion between the charging roller and the electrophotographic photosensitive member.
In order to make the contact nip width uniform when the roller rotates, it is preferable that the outer diameter fluctuation of the conductive base layer roller is small.

The conductive elastic layer 2 is bonded to the conductive support 1 via an adhesive as necessary. In this case, the adhesive is preferably conductive. In order to make it conductive, a known conductive agent can be used as the adhesive.
The binder of the adhesive may be any of thermosetting and thermoplastic resins. For example, a known adhesive such as urethane, phenol, acrylic, polyester, polyether, or epoxy may be used. Can be used. Moreover, what was quoted in the said electroconductive elastic layer can be used as a electrically conductive agent for providing electroconductivity to an adhesive agent. The conductive agents can be used alone or in combination of two or more.

<Outermost layer>
In the present invention, after the conductive elastic layer 2 is produced, the outermost layer 3 is formed as the covering layer. As the binder material used for the outermost layer 3, a resin or an elastomer is preferable.
Examples of the resin include fluorine resin, polyamide resin, acrylic resin, polyurethane resin, silicone resin, butyral resin, styrene-ethylene-butadiene-olefin copolymer (SEBC), olefin-ethylene-butylene-olefin copolymer (CEBC), etc. Is mentioned.

Examples of the elastomer include synthetic rubber and thermoplastic elastomer.
Examples of the synthetic rubber include natural rubber (such as vulcanization treatment), EPDM, SBR, silicone rubber, urethane rubber, IR, BR, NBR, CR, and the like.
As thermoplastic elastomers, polyolefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polystyrene-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, ethylene vinyl acetate-based thermoplastic elastomers, polyvinyl chloride-based thermoplastic elastomers And chlorinated polyethylene-based thermoplastic elastomers.

These binder materials may be used singly or as a mixture of two or more thereof. The outermost layer 3, which may be a copolymer, adds conductivity by adding conductive fine particles. As the conductive fine particles, the electron conductive agents listed in the conductive elastic layer can be used, and one kind or a combination of two or more kinds can be used.

As the blending amount of the conductive agent blended in the outermost layer 3 of the present invention, the volume resistivity of the charging roller is a medium resistance region (volume resistivity is low) in any of a low temperature and low humidity environment, a normal temperature and normal humidity environment, and a high temperature and high humidity environment. 1 × 10 ⁴ Ω · cm to 1 × 10 ⁸ Ω · cm) is preferable. Each environment is a low temperature and low humidity environment (15 ° C./10% RH), a normal temperature and normal humidity environment (23 ° C./50% RH), and a high temperature high humidity environment (30 ° C./80% RH).

There are two reasons why the volume resistivity of the charging roller is preferably 1 × 10 ⁴ Ω · cm or more. (1) When there is a pinhole in the photosensitive member as a member to be charged, a large current is concentrated at once in the pinhole, the applied voltage drops, and the charging potential becomes a band on a high-definition halftone image. It can be avoided that a portion lacking appears. (2) It is possible to avoid the occurrence of a problem such as making the pinhole larger. Conversely, when the volume resistivity is 1 × 10 ⁸ Ω · cm or less, it is not necessary to apply a high voltage in order to obtain a required charging potential.
Further, as a method for forming the outermost layer 3, a coating liquid in which fine particles are dispersed by dissolving a binder material is prepared, and this is formed by a ring coating method.

<Ring coating>
Next, the manufacturing method of the roller member of the present invention (the ring coating method for forming the outermost layer 3 on the surface of the conductive base layer roller 26) will be described in detail with reference to FIGS.
(1) The conductive base layer roller 26 obtained by the above method is supported in the vertical direction using a holding member 25 as shown in FIG.
(2) The ring application head surrounds the outer peripheral surface of the conductive base layer roller 26 (shaft body) over the entire circumference and is disposed at a predetermined distance from the central axis of the shaft body. Further, the ring application head is disposed at a predetermined position (application start position) with respect to the conductive base layer roller 26 at the start of application. The ring application head has an annular inner diameter variable member 23. The inner diameter variable member 23 can change the inner diameter, and is provided below the discharge port 28 of the ring coating head. In the example shown in FIG. 2, the discharge port 28 is formed between the upper piece member 21 and the lower piece member 22, and the inner diameter of the upper piece member 21 is larger than the inner diameter of the lower piece member 22.
The ring application head has one or more supply ports 27 for supplying the application liquid to the ring application head by an application liquid supply means (syringe pump not shown) outside the ring application head. In addition, the ring coating head discharges the liquid uniformly in the circumferential direction, so that the coating liquid is merged and distributed in the circumferential direction at one or more locations in the coating liquid distribution chamber (not shown). It is desirable to have one or more parts (not shown).

  The inner diameter variable member 23 is disposed at a distance that forms a predetermined gap with respect to the conductive base layer roller 26. The gap distance depends on the viscosity of the paint to be used, but from the viewpoint of preventing defects due to coating such as dripping and preventing contact between the conductive base layer roller 26 and the inner diameter variable member 23. It is preferable to be in the range of 0.5 mm.

(3) The coating liquid (uncured outermost layer) is formed by discharging the coating liquid from the discharge port 28 of the ring coating head while relatively moving the ring coating head and the shaft in the longitudinal direction of the conductive base layer roller 26. To do. The outer diameter of the conductive base layer roller 26 (shaft body) changes in the longitudinal direction (axial direction). While the shaft body and the ring application head are relatively moved in the axial direction, the change amount of the inner diameter of the annular inner diameter variable member 23 is substantially equal to the change amount of the outer diameter of the conductive base layer roller 26. The inner diameter of the inner diameter variable member 23 is changed. By changing in this way, the difference between the inner diameter of the inner diameter variable member 23 and the outer diameter of the shaft body is maintained substantially constant while the shaft body and the ring application head are relatively moved in the axial direction. . The outer diameter of the conductive base layer roller may be measured in advance, or may be measured during coating by installing an outer diameter measuring device near the ring coating head. As a method of changing the inner diameter of the inner diameter variable member, for example, the inner diameter variable member is formed by an elastic body and an external force is applied to the elastic member to change the inner diameter variable member (FIGS. 2 and 7), or the inner diameter variable member is formed by a tubular member. And the method (FIG. 3) etc. which change the internal pressure of a tubular member are mentioned.
Further, the relative movement speed, the discharge amount of the coating liquid, and the discharge speed can be appropriately selected depending on the film thickness of the outermost layer 3 and the physical properties of the coating liquid.

As shown in FIG. 7, the outer diameter of the conductive base roller 26 is D ₀ , the inner diameter of the inner diameter variable member 23 is D ₁ , the inner diameter of the upper piece member 21 is D ₂ , and the inner diameter of the lower piece member 22 is D ₃ . If, the inner diameter _{D 3} of the inner diameter _{D 2} and Shitakoma member 22 of Kamikoma member 21 does not change. In the example of FIG. 7, the inner diameter _{D 2} is equal to the inner diameter _{D 2} and 7 shown in FIG. 7 (a) (b), an inside diameter _{D 3} and 7 inside diameter _{D 3} of (b) in FIG. 7 (a) equal. Further, the inner diameter D ₂ of the upper piece member 21 in FIG. 7 is larger than the inner diameter D _{3 of the} lower piece member 22.
On the other hand, the outer diameter D ₀ of the conductive base layer roller 26 changes in the longitudinal direction of the conductive base layer roller 26. In the example of FIG. 7, the outer diameter _{D 0} in FIG. 7 (b) larger than the outer diameter _{D 0} in FIG. 7 (a). However, the outer diameter D ₀ of the conductive base layer roller 26 is changed, by changing also the inner diameter D ₁ of the inner diameter variation member 23 accordingly, the difference between the inner diameter D ₁ and an outer diameter D ₀ substantially constant Can be maintained. In the example of FIG. 7, the inner diameter _{D 1} of the FIG. 7 (b) greater than the inner diameter _{D 1} of the FIG. 7 (a). Then, a value obtained by subtracting the outer diameter _{D 0} in FIGS. 7 (a) from the inner diameter _{D 1} in FIG. 7 (a), subtracting the outer diameter _{D 0} in FIG. 7 (b) from the inner diameter _{D 1} in FIG. 7 (b) Is approximately equal to
The relationship between “the difference between the inner diameter D ₁ and the outer diameter D ₀ ” and “the distance of the gap between the inner diameter variable member 23 and the conductive base layer roller 26” is as follows.
Distance of gap = (inner diameter D ₁ of inner diameter variable member 23−outer diameter D _{0 of} conductive base layer roller 26) / 2

Hereinafter, the present invention will be described in more detail with reference to examples.
(Preparation of conductive base layer roller 1)
The materials shown in Table 1 were added and kneaded for 10 minutes in a closed mixer adjusted to 50 ° C. The material shown in Table 2 was added thereto, and the mixture was further kneaded for 5 minutes with an open roll cooled to 20 ° C. to obtain an epichlorohydrin rubber kneaded product.

  Subsequently, the above-mentioned epichlorohydrin rubber kneaded product was extruded into a cylindrical shape having an outer diameter of 13.5 mm and an inner diameter of 5.5 mm with an extruder, and cut into a length of 250 mm. Thereafter, primary vulcanization was performed in steam at a temperature of 160 ° C. for 40 minutes using a steam vulcanization can to obtain a rubber primary vulcanization tube for a conductive elastic layer.

  Next, a thermosetting adhesive (Metallock U-20 manufactured by Toyo Chemical Laboratories) was applied to the central part 231 mm of a steel cylinder (surface is nickel-plated) having a diameter of 6 mm and a length of 256 mm, and dried at 80 ° C. for 10 minutes The conductive support thus obtained was inserted into the rubber primary vulcanization tube. Thereafter, heat treatment was performed in an electric oven at 150 ° C. for 1 hour to obtain an unpolished roller.

  In this unpolished roller, both ends of the rubber part were cut off, and the length of the rubber part was 232 mm. Thereafter, the rubber portion was polished with a rotating grindstone, and the conductive base layer roller 1 was obtained with a crown shape having a diameter of 11.70 mm on both sides from the center and a diameter of 12.10 mm at the center.

(Preparation of conductive base layer roller 2)
The conductive base layer roller 1 was extruded with an extruder to an outer diameter of 17.5 mm and an inner diameter of 5.5 mm. Further, when the rubber portion was polished with a rotating grindstone, the conductive base layer roller 2 was obtained with a crown shape having a diameter of 15.60 mm on both sides from the center and a diameter of 16.10 mm at the center.

(Preparation of conductive base layer roller 3)
In the conductive base layer roller 1, the epichlorohydrin rubber kneaded product was extruded into a cylindrical shape having an outer diameter of 13.5 mm and an inner diameter of 5.5 mm using an extruder, and was cut into a length of 320 mm. Thereafter, primary vulcanization was performed in steam at a temperature of 160 ° C. for 40 minutes using a steam vulcanization can to obtain a rubber primary vulcanization tube for a conductive elastic layer.

Next, a thermosetting adhesive (Metallock U-20, manufactured by Toyo Chemical Laboratory) is applied to the central part 308 mm of a steel cylinder (surface is nickel-plated) having a diameter of 6 mm and a length of 340 mm, and dried at 80 ° C. for 10 minutes. The conductive support thus obtained was inserted into the rubber primary vulcanization tube. Thereafter, heat treatment was performed in an electric oven at 150 ° C. for 1 hour to obtain an unpolished roller. Both ends of the rubber portion were cut off in the unpolished roller, and the length of the rubber portion was 310 mm. Thereafter, the rubber portion was polished with a rotating grindstone, and the conductive base layer roller 3 was obtained with a crown shape having a diameter of 11.60 mm at both sides 154 mm from the center and a diameter of 12.10 mm at the center.

(Preparation of conductive base layer roller 4)
The both ends of the rubber of the conductive base layer roller 3 were subjected to R surface processing as shown in FIG. 5 to obtain the conductive base layer roller 4.
(Preparation of conductive base layer roller 5)
Both ends of the rubber of the conductive base layer roller 3 were subjected to C-surface processing as shown in FIG. 6 to obtain a conductive base layer roller 5.

(Preparation of coating solution 1)
The raw materials shown in Table 3 were prepared.

  A mixed solution was prepared using the above raw materials as a glass bottle. This was filled with glass beads (average particle size: 0.8 mm) as a dispersion medium so that the filling rate would be 75%, and dispersed for 15 hours using a paint shaker disperser. A mixture of hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI) each butanone oxime block body 1: 1 was added to the dispersion solution so that NCO / OH = 1.0, thereby preparing coating solution 1. The viscosity of the coating liquid 1 at this time was 23 mP · s. The viscosity was measured using a digital bistron viscometer (manufactured by Shibaura System Co., Ltd.).

(Preparation of coating solution 2)
The raw materials shown in Table 4 were prepared.

  After mixing the raw materials, the mixture was stirred at room temperature and then heated to reflux for 24 hours to hydrolyze and condense the hydrolyzable silane compound to obtain a hydrolyzable condensate. By adding this hydrolyzable condensate to a mixed solvent of 2-butanol / ethanol, a hydrolyzable condensate-containing alcohol solution having a solid content of 7% by mass was prepared. To 100 g of this hydrolyzable condensate-containing alcohol solution, 0.35 g of an aromatic sulfonium salt (trade name: Adekaoptomer SP-150, manufactured by Asahi Denka Kogyo Co., Ltd.) as a photocationic polymerization initiator was added. . Furthermore, it diluted with ethanol so that solid content might be 0.5 mass%, and the coating liquid 2 for thin film layers was obtained. The viscosity of the coating liquid 2 at this time was 4 mP · s.

(Evaluation)
Ten charging rollers were prepared under the above conditions, and it was visually confirmed whether there was any coating unevenness in each. The evaluation is A when there is no visible coating unevenness, and there is coating unevenness, but B when there is no problem when used as a charging roller, and there is coating unevenness and charging. C was used when it was not suitable for use as a roller.

[Example 1]
(Formation of outermost layer)
The cored bar portions at both ends of the conductive base layer roller 1 were held by the holding member 25 so that the conductive base layer roller 1 was in a vertical state.
Next, as shown in FIG. 2, an annular inner diameter variable member whose inner diameter is adjusted so as to form a uniform gap of 0.15 to 0.25 mm over the entire circumference with respect to the end surface of the rubber portion of the conductive base layer roller 1. A ring application head equipped with The slit width of the slit-like discharge port 28 of the ring application head was 0.1 mm. The ring coating head was moved so that the position of the discharge port 28 of the ring coating head was at the upper end surface of the conductive base layer roller 1. Therefore, 0.02 ml of the coating liquid 1 is discharged from the ring coating head, and then the coating liquid 1 is discharged from the syringe pump while moving the ring coating head vertically downward (longitudinal direction of the roller) at 30 mm / s, thereby providing conductivity. A coating film (uncured thin film layer) was formed on the base layer roller 1. At that time, the inner diameter of the annular inner diameter variable member was changed so as to always form a gap of 0.1 mm to 0.3 mm with respect to the conductive base layer roller. As a method of changing the inner diameter, the pressing pressure of the pressing member 24 (P in FIG. 7) and the inner diameter change amount of the annular inner diameter variable member 23 are measured in advance, and the outer diameter of the conductive base layer roller 1 measured separately is measured. The pressing pressure of the pressing member 24 (P in FIG. 7) was changed in the longitudinal direction of the roller. The inner diameter variable member 23 is made of fluoro rubber (FFKM).
Thereafter, it was air-dried at room temperature for 30 minutes or more, and subsequently dried in a hot air circulating dryer at a temperature of 160 ° C. for 1 hour to cure and dry the coating film, whereby the charging roller 1 having the outermost layer was obtained.

[Examples 2 to 5]
A charging roller was prepared in the same manner as in Example 1 except that the conductive base layer roller 1 was changed to conductive base layer rollers 2 to 5 shown in Table 5, and charging rollers 2 to 5 were obtained.

Example 6
The coating liquid 2 was applied to the conductive base layer roller 3 in the same manner as in Example 1. At this time, EPDM was used as the material of the inner diameter changing member 23.
Thereafter, the outermost layer was formed by irradiating ultraviolet rays with a high output low pressure mercury lamp (manufactured by Harrison Toshiba Lighting) for 4 minutes to obtain a charging roller 6. The high-output low-pressure mercury lamp is mainly ultraviolet light having a wavelength of 254 nm, and the ultraviolet light accumulated at this time was about 8000 mJ / cm 2 (ultraviolet intensity is 35 mW / cm 2).

Example 7
A charging roller was prepared in the same manner as in Example 6 except that the conductive base layer roller 3 was changed to the conductive base layer roller 4, and a charging roller 7 was obtained.

Example 8
(Formation of outermost layer)
The conductive base layer roller 1 was held in a vertical state by members that hold the cored bar portions at both ends of the conductive base layer roller 1.
Next, as shown in FIG. 3, an annular inner diameter variable member 31 having an inner diameter adjusted so as to form a uniform gap of 0.1 to 0.3 mm over the entire circumference with respect to the end surface of the rubber portion of the conductive base layer roller 1. A ring application head equipped with The annular inner diameter variable member 31 shown in FIG. 3 has a tube shape, and the inner diameter is changed by injecting air from an air injection port (not shown). Teflon (registered trademark) coated rubber was used for the annular inner diameter variable member 31. Otherwise, the charging roller 8 was obtained in the same manner as in Example 1.

[Examples 9 to 12]
A charging roller was prepared in the same manner as in Example 8 except that the conductive base layer roller 1 was changed to conductive base layer rollers 2 to 5 shown in Table 5, and charging rollers 9 to 12 were obtained.

(Comparative Example 1)
In Example 8, coating was performed using a ring coating head (FIG. 4) that does not include an annular inner diameter variable member. Here, the inner diameter of the portion where the lower piece of the ring coating head is closest to the conductive base roller 1 was 12.2 mm. Otherwise, the outermost layer was formed in the same manner as in Example 8 to obtain the charging roller 13.

(Comparative Examples 2 to 4)
In Comparative Example 1, the outermost layer was formed as the conductive base layer rollers 3 to 5 shown in Table 5 as the conductive base layer roller 2 to obtain charging rollers 14 to 16.
Table 5 shows the evaluation results for each charging roller.

DESCRIPTION OF SYMBOLS 1 ... Conductive support body 2 ... Conductive elastic layer 3 ... Outermost layer 21 ... Upper piece member 22 ... Lower piece member 23 ... Inner diameter variable member 24 ... Pressing member 25 ... Holding member 26 ... Conductive base layer roller 27 ... Supply port 28 ... Coating outlet 31 ... Inner diameter variable member (tubular)

Claims (7)

A shaft body that is supported in the vertical direction and has an outer diameter that varies in the axial direction; a ring coating head that surrounds the entire outer peripheral surface of the shaft body and is disposed at a predetermined distance from the central axis of the shaft body; Is a method of manufacturing a roller member having a step of forming a coating film on the outer peripheral surface of the shaft body by discharging a coating liquid from the discharge port of the ring coating head while relatively moving the shaft in the axial direction. And
The ring application head has an inner diameter variable member capable of changing an inner diameter below the discharge port ,
The process, to also maintain the difference between the outer diameter of the inner diameter and the shaft of the inner diameter of the variable member substantially constant while relatively moving the said shaft body and the ring coating head in axial direction A step of changing the inner diameter of the inner diameter variable member according to the outer diameter of the shaft body.
A method for manufacturing a roller member.   The method for manufacturing a roller member according to claim 1, wherein the inner diameter of the inner diameter variable member is changed so that the amount of change in the inner diameter of the inner diameter variable member is substantially equal to the amount of change in the outer diameter of the shaft body.   The roller member manufacturing method according to claim 1, wherein the inner diameter variable member is an elastic body, and the inner diameter of the inner diameter variable member is changed by changing an external force applied to the inner diameter variable member. Method for producing a roller member according to any one of 請 Motomeko 1-3 that the shaft body having a crown shape. The discharge port is formed between the Kamikoma member and Shitakoma member, the roller of the inner diameter of the upper frame member according to any one of size I請 Motomeko 1-4 than the inner diameter of the lower frame member Manufacturing method of member.   A ring coating head which surrounds the outer peripheral surface of the shaft body supported in the vertical direction over the entire circumference and is disposed at a predetermined distance from the central axis of the shaft body, and moves relative to the shaft body in the axial direction. A ring applicator comprising:
  The ring application head is
      A discharge port for discharging the coating liquid;
      An annular inner diameter variable member that is provided below the discharge port and can change the inner diameter;
Have
  The inner diameter variable member is made of an elastic body,
  The ring coating apparatus further includes a pressing member that changes an inner diameter by applying an external force to the inner diameter variable member.   The ring application according to claim 6, wherein the inner diameter varying means changes the inner diameter of the inner diameter variable member so that the amount of change in the inner diameter of the inner diameter variable member is substantially equal to the amount of change in the outer diameter of the shaft body. apparatus.