JP2001350351A - Method of manufacturing roller for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a roll for an image forming device by which a good image can be imparted by obtaining a uniform pressurizing force and a nip width against an object over the whole roller. SOLUTION: In the roller for the image forming device, elastic material is ground and processed utilizing a flat shaped grindstone of a type that is perpendicular on end edge parts and an elastic body layer of a psuedo-fusiform type provided with a construction where a central cylinder part, tapered state base parts of cones that are each connected to both ends of the cylinder part are identical shapes and cylinder parts with smaller diameters than the cylinder part in the center but are identical shapes are connected to both ends of the base parts of the cones is provided on an outer periphery of a rotating central shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a roller for an image forming apparatus. More specifically, the present invention provides
An image forming apparatus roller having a pseudo spindle type elastic layer and used as a charging roller, a developing roller, a transfer roller, a toner supply roller, a cleaning roller, and the like, an edge portion used in the manufacture of a normal cylindrical roller The present invention relates to an industrially advantageous method for efficiently manufacturing a vertical flat grindstone.

[0002]

2. Description of the Related Art In recent years, with the development of electrophotographic technology, image forming apparatuses such as dry electrophotographic apparatuses have been used for charging, developing, and the like.
Polymer members have been attracting attention as members of parts used for transfer, toner supply, cleaning, etc., and generally have elasticity such as a charging roller, a developing roller, a transfer roller, a toner supply roller, and a cleaning roller. It is used in the form of a roller. In processes such as charging and transfer using an elastic roller, this polymer member has the advantage that compared to conventional corotron chargers, the required image forming body charging potential and toner transfer amount can be obtained with a lower power supply voltage. is there. For the polymer members used for these purposes, polymer elastomers or foams such as rubber or polyurethane are usually used, and these have low hardness and contaminate image forming bodies and transfer materials. In many cases, it is required to have a predetermined resistance value in a medium resistance region of 10 ⁴ to 10 ¹⁰ Ω.

FIG. 1 is a schematic view showing an example of an image forming apparatus of an electrophotographic type, in which a toner supply roller (toner supply member) 3 and an image forming body (an electrostatic latent image) holding a latent electrostatic latent image are shown. The developing roller 2 is disposed between the image forming body 1 and the image bearing member 1 via a transfer material 8 such as paper. 2 shows a structure in which the transfer roller 5 is brought into contact with the transfer roller 5. The toner is supplied to the surface of the developing roller 2 by the toner supply roller 3 by rotating the toner supply roller 3, the developing roller 2, and the image forming body 1 in the direction of the arrow, and is formed into a uniform thin layer by the layer regulating blade 4. After being formed, the image forming body 1
Attach to the upper latent image and the latent image is visualized. Then, an electric field is generated between the image forming body 1 and the transfer roller 5 to transfer the toner image on the image forming body 1 to the transfer material 8. A cleaning roller 6 removes toner remaining on the surface of the image forming body 1 after transfer. Reference numeral 7 denotes a charging roller. Each of these rollers is usually used in a state of being pressed against a target member, and a method of pressing the both ends of the roller in the direction of the target object by a spring or the like is generally used as a means for pressing. I have. However, according to such a pressing method, when the roller has a cylindrical shape, the pressing force against the object is different between the vicinity of both ends of the roller and the center, and both ends are larger than the center. . Since the roller is made of an elastic material, for example, in a transfer roller, the nip width (length in the running direction of the transfer material) is about 2 to 4 times larger at both ends than at the center. Prone.

Therefore, if each roller operates in such a state, the pressing force and the nip width of the roller are not uniform, and there is a possibility that an image defect may occur. For example, in the case of a transfer roller, the nip width is small in the central portion of the transfer material, and as a result, the transfer material is not sufficiently exposed to the transfer electric field, which may cause transfer failure, and the transfer pressure is excessively high. , The character image may have a void. In order to solve such a problem, there has been proposed a crown-type transfer roller in which a central portion is enlarged in a range of less than 5% as compared with both end portions (Japanese Patent Application Laid-Open No. Hei 4-2980). . However, in the case of manufacturing such a shape by grinding an elastic material with a grindstone, it is not possible to use a flat grindstone having a vertical edge portion which is generally used for manufacturing a cylindrical roller,
Since a flat type grinding wheel with an edge R is used, when manufacturing a cylindrical roller and a crown roller on the same manufacturing line,
Each time, the whetstone has to be replaced, which is troublesome. In addition, when manufacturing on a separate line, a new manufacturing line must be provided, which inevitably increases the manufacturing cost.

[0005]

SUMMARY OF THE INVENTION Under such circumstances, the present invention provides a roller for an image forming apparatus which can provide a uniform image contact force and a nip width with respect to an object over the entire roller and provide a good image. It is an object of the present invention to provide an industrially advantageous method for efficiently manufacturing a flat type grinding wheel having a vertical edge portion which is generally used for manufacturing a cylindrical roller.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a roller having a pseudo spindle type elastic layer having a specific structure has a uniform pressure contact with an object. It has been found that a force and a nip width can be obtained, and that it can be easily manufactured by a flat grinding wheel having a vertical edge portion.
The present invention has been completed based on such findings. That is, the present invention is a method of manufacturing a roller having a pseudo spindle type elastic body layer on the outer periphery of a rotation center axis by grinding an elastic material using a flat grinding wheel having a vertical edge portion, A mold elastic body layer has a central cylindrical portion, a tapered frustoconical portion of the same shape connected to both ends thereof, respectively, connected to both ends of each frustoconical portion and having the same diameter smaller than the central cylindrical portion. An object of the present invention is to provide a method for manufacturing a roller for an image forming apparatus, which has a structure in which a cylindrical portion having a shape is integrated. The present invention also provides an image forming apparatus provided with a roller manufactured by this manufacturing method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The method of manufacturing a roller for an image forming apparatus according to the present invention is characterized in that a pseudo-spindle type elastic material is formed on the outer periphery of a rotation center shaft by grinding an elastic material using a flat grinding wheel having a vertical edge portion. This is a method of manufacturing a roller having a body layer (hereinafter, may be referred to as a pseudo-spindle type roller). FIG. 2 is a side view of an example of a roller for an image forming apparatus obtained by the method of the present invention. The roller of the present invention has a pseudo spindle type elastic layer 2 provided on the outer periphery of a rotation center shaft 1. The pseudo spindle-shaped elastic layer 2 has a central cylindrical portion 3 and tapered frustoconical portions 4 and 4 ′ having the same shape connected to both ends thereof, respectively.
It is connected to both ends of the truncated cone portions 4 and 4 ', respectively, and has a structure in which the same cylindrical portions 5 and 5' having a smaller diameter than the central cylindrical portion 3 are integrated. In the above roller, the outer diameter of the central cylindrical portion 2 is preferably 0.1 to 5%, more preferably 0.3 to 5% with respect to the outer diameter of the cylindrical portions 5, 5 'at both ends.
A large value of 3%, particularly preferably in the range of 0.5 to 2% is desirable from the viewpoint of performance.

The ratio of the length of the central cylindrical portion 3, the two truncated cone portions 4, 4 'and the cylindrical portions 5, 5' at both ends of the roller is preferably 1: 1.5 to 5.0: 0. 8-3.0, more preferably 1: 1.8-4.0: 1.0-2.5, particularly preferably 1: 2.0-3.0: 1.0-2.0. It is desirable from the viewpoint of performance. The pseudo-spindle type roller having such a shape can obtain a uniform pressing force and a nip width with respect to an object similarly to the crown type roller, and can be used as a roller for an image forming apparatus, specifically, a charging roller, a developing roller, Used as a transfer roller, a toner supply roller, a cleaning roller, and the like, and can provide a good image.

It is particularly advantageous that the pseudo spindle type roller of the present invention is applied as a transfer roller among the above rollers. When the roller of the present invention is applied to each of the above rollers, a conductive elastic layer is generally used as the elastic layer. In the method of the present invention, the pseudo spindle roller is manufactured by grinding an elastic material using a flat grinding wheel having a vertical edge portion. The edge type vertical grinding wheel is a grinding wheel used for manufacturing a normal cylindrical roller. For example, in a normal grinding wheel using a vitrified binder, the shape defined by JIS has a flat shape (or No. 1). ) And has an A-shaped edge.
Incidentally, an R-shaped flat grindstone having an edge portion used for manufacturing a crown-type roller has a flat shape (or No. 1) defined by JIS and an F-shaped edge portion. .

FIG. 3 shows a flat grinding wheel having a vertical edge portion.
It is a side explanatory view showing an example of the procedure which manufactures the quasi-spindle type roller of the present invention by grinding an elastic material, and as shown in this figure, first, a cylindrical portion is formed by a flat grinding wheel 6 having a vertical edge portion. After grinding 5, the grindstone 6 is moved from (a) to (b) to grind the truncated cone 4. Next, the grindstone 6 is moved from (b) to (c) to grind the central cylindrical portion 3, and then the grindstone 6 is moved from (c) to (d) to grind the frustoconical portion 4 '. The cylindrical portion 5 'is ground. The P portion of the grindstone 6 is a contact portion with the elastic material of the work material, and the grinding process is performed at this portion. The above-mentioned grinding is a method of fixing the elastic material of the work material and moving the grindstone. On the contrary, fixing the grindstone and moving the elastic material of the work material in the rotation axis direction. , Can be ground. These grinding processes are performed by rotating the grindstone or the work material in the rotation axis direction of the work material while rotating the work material at a low speed while rotating the grindstone at a high speed. In the method of the present invention, as the elastic material used as the work material, an ordinary cylindrical material having an elastic layer on the outer periphery of the rotation center shaft is used.

The material of the elastic layer is not particularly limited, and may be selected from those known as rollers for image forming apparatuses.
It can be appropriately selected and used. Such materials include, for example, polyurethane, ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (E
PR), natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber,
Examples include elastomers such as styrene-butadiene rubber, chloroprene rubber, and acrylic rubber, and foams thereof. Among these, a polyurethane foam is preferable, and when a conductive elastic layer is required, a conductive polyurethane foam is preferably used. Such a polyurethane foam can be produced, for example, by subjecting a polyurethane molding material to foam curing by using both inert gas and mechanical stirring.

In this method, a polyurethane molding material containing a polyol component, a polyisocyanate component, and a conductivity-imparting agent, a foam stabilizer, a urethane reaction catalyst, and the like, which are optionally used, is used. Examples of the polyol component used in the polyurethane molding material include water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, methylglycodite, aromatic diamine, Addition polymerization of alkylene oxides such as eletin oxide and propylene oxide with sorbitol, sucrose, phosphoric acid, etc. as starting materials, polymer polyols modified with polytetramethylene ether glycol, acrylonitrile, styrene, etc., polyols with melamine added to polyols Polyester polyol obtained by condensing an acid component such as adipic acid and a glycol component such as ethylene glycol, ε-caprolacter Polyester polyols obtained by ring-opening polymerization, polycarbonate diols, diols such as butanediol, triols and their derivatives such as trimethylolpropane.

Among these polyol components, polyether polyols are preferred. Particularly, polyether polyols and polytetramethylene ether glycol obtained by addition polymerization of alkylene oxide can be obtained by combining inert gas introduction and mechanical stirring. This is preferable since the cell diameter is stabilized when the composition is foamed and cured. Examples of the polyether polyol obtained by addition polymerization of the above alkylene oxide include, for example, water, propylene glycol,
Preferable examples include polyether polyols obtained by adding ethylene oxide and propylene oxide using ethylene glycol, glycerin, trimethylolpropane, hexanetriol, and the like as starting materials. These polyol components may be used alone or in combination of two or more.

Examples of the polyisocyanate component used in the polyurethane molding material include various aromatic polyisocyanate compounds such as diphenylmethane diisocyanate and tolylene diisocyanate or derivatives thereof;
Examples thereof include various aliphatic polyisocyanate compounds such as hexamethylene diisocyanate or derivatives thereof, and alicyclic polyisocyanate compounds such as isophorone diisocyanate or derivatives thereof. Among these polyisocyanate compounds, various aromatic polyisocyanate compounds and derivatives thereof are particularly preferable because the cell diameter becomes stable when foaming and curing are performed by using both inert gas and mechanical stirring. Also, any polyisocyanate compound can be used as a derivative,
Polyurethane modified urethane modified product, dimer by uretidion formation, isocyanurate modified product, carbodiimide / uretonimine modified product, allohanate modified product,
Modified urea, modified buret, etc. are used,
Particularly preferred are urethane-modified products and carbodiimide / uretonimine-modified products. These polyisocyanate components may be used alone or in combination of two or more. The polyol component and the polyisocyanate component have an NCO group / OH group molar ratio of 0.9 to 1.5, preferably 1.0 to 1.0.
Advantageously, it is used in such a ratio that it is in the range of -1.2.

As the conductivity-imparting agent, a carbon conductive agent, an ionic conductive agent, or the like can be used. As the carbon conductive agent, for example, gas black such as electrified black, Ketjen black, acetylene black,
Examples include oil furnace black including ink black, thermal black, channel black, lamp black, and the like. Examples of the ionic conductive agent include octadecyltrimethylammonium such as dodecyltrimethylammonium such as tetraethylammonium, tetrabutylammonium and lauryltrimethylammonium, and stearyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium and modified aliphatic dimethylethylammonium. Chlorate, chlorate, hydrochloride, bromate, iodate,
Ammonium salts such as borofluoride, sulfate, alkyl sulfate, carboxylate and sulfonate: perchlorates and chlorates of alkali metals or alkaline earth metals such as lithium, sodium, calcium and magnesium , Hydrochloride, bromate, iodate, borofluoride, trifluoromethyl sulfate, sulfonate and the like. Of these, quaternary ammonium salts of alkyl sulfates and quaternary ammonium salts of polybasic carboxylic acids are particularly preferred because of a small increase in resistance during continuous energization.

These conductive agents may be used alone or in combination of two or more. The amount is not particularly limited and is appropriately selected according to various situations.
Usually, the polymer material 10 constituting the polyurethane foam
0.1 to 40 parts by weight, preferably 0.1 to 40 parts by weight, based on 0 parts by weight.
It is blended at a ratio of 3 to 20 parts by weight. Further, as a foam stabilizer, for example, when a silicone-based surfactant composed of a polydimethylsiloxane-polyoxyalkylene copolymer is foamed and cured by a combination of introduction of an inert gas and mechanical stirring, the cell diameter is stable. Therefore, it is preferable. The molecular structure of the polydimethylsiloxane-polyoxyalkylene copolymer generally has a polydimethylsiloxane portion having a molecular weight of about 350 to 15,000 and a molecular weight of 200 to 9000.
Consisting of about 0 polyoxyalkylene moieties, the molecular structure of the polyoxyalkylene moiety is preferably an ethylene oxide addition polymer or a co-addition polymer of ethylene oxide and propylene oxide, and preferably has a terminal ethylene oxide. . Further, an ionic surfactant such as a cationic, anionic or amphoteric surfactant, or a nonionic surfactant such as various polyethers or polyesters may be used together with the silicone-based surfactant.

The amount of the silicone surfactant is as follows:
Generally, 0.1 to 1 per 100 parts by weight of the polyol component
A range of 0 parts by weight is preferable, and a range of 0.5 to 5 parts by weight is particularly preferable. On the other hand, as the urethane reaction catalyst, for example, known catalysts such as monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines, and organometallic compounds are used alone or in combination of two or more. be able to. When foaming and curing are performed by introducing inert gas and mechanical stirring in combination among these, from the viewpoint of stabilizing the cell diameter, particularly stannas octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker peptide, Organic metal compounds such as dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin marker peptide, dioctyltin thiocarboxylate, phenylmercuric propionate and octenoate are preferred.

As a method for producing a polyurethane foam, for example, a polyurethane molding material containing a polyol component, a polyisocyanate component and, if desired, a conductivity-imparting agent, a foam stabilizer, a urethane reaction catalyst, etc., is mixed with an inert gas while mechanically stirring. Introduce air bubbles and pour them into a predetermined mold or the like, or foam them freely in a block shape, and then heat and cure, or the polyol component is converted into isocyanate in advance, and ethylene glycol or A prepolymer method of foaming and curing in the same manner as described above using a chain extender such as 1,4-butanediol and trimethylolpropane can be used. The center axis of rotation of the elastic material used in the method of the present invention may be, for example, plastic such as ABS, POM, polycarbonate, nylon, or a metal member obtained by plating steel such as sulfur free-cutting steel with zinc or the like, aluminum, stainless steel, or the like. A metal member such as steel or a magnesium alloy may be used. In the case of manufacturing a conductive pseudo spindle roller, a metal member is preferably used as a rotation center axis.

The joining method of the metal member and the polyurethane foam is not particularly limited, but a method in which the metal member is disposed in advance in a mold and the polyurethane molding material is cast and cured, or the polyurethane foam is fixed to a predetermined shape. A method of bonding after forming into a shape can be used. In either method, an adhesive layer can be provided between the metal member and the polyurethane foam as necessary.For this adhesive layer, a known material such as an adhesive made of a conductive paint or a hot melt sheet is used. Can be. The thus obtained elastic material is ground into a pseudo-spindle type using a flat grindstone having a vertical edge portion as described above, whereby a roll for an image forming apparatus of the present invention is obtained.

[0020]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Production Example 1 Production of Elastic Material for Work Material Propylene oxide and ethylene oxide were randomly added to glycerin, and the content of oxyethylene units was 16
Weight%, the number of functional groups is substantially 3, weight average molecular weight 500
A polyether polyol having an OH value of 34 mgKOH / g was produced. 60 parts by weight of this polyether polyol, a weight average molecular weight of 2,000 and an OH value of 56 mg KOH
/ G of polytetramethylene ether glycol, 15 parts by weight of a mixture of diphenylmethane diisocyanate, urethane-modified diphenylmethane diisocyanate and carbodiimide-modified diphenylmethane diisocyanate having an isocyanate group content of 26.3% by weight, dimethylpolysiloxane-polyoxygen 4 parts by weight of a silicone foam stabilizer having an OH value of 32 mgKOH / g as an alkylene copolymer, 1 part by weight of lauroyl iminopropyldimethylethylammonium ethyl sulfate, 0.005 part by weight of dibutyltin dilaurate, and a black pigment dispersed in a polyol 3 parts by weight of a black colorant having an OH value of 56 mgKOH / g were mixed while being foamed by mechanical stirring, and the mixture was mixed with gold having a metal shaft having a diameter of 6 mm as a center. After cast into, and 10 hours cured by heating at 100 ° C., to produce a polyurethane foam elastic material length 290mm diameter 19 mm. The bulk density of the foam part is 0.40 g / ml, Asker C hardness 38 °, average cell diameter 100 μm, maximum cell diameter 160 μm
Met. In the same manner as above, a total of seven polyurethane foam elastic materials having substantially the same properties were produced.

Example 1 The polyurethane foam elastic material 6 obtained in Production Example 1
About the individual, flat edge whetstone vertical edge (manufactured by Teiken,
Product name: PT Toshi GC36GH23V4PO], and six quasi-spindle-type rollers (No. 1 to No. 1) having the shape shown in FIG.
6) was produced. The outer diameter of each roller at each position in the longitudinal direction was measured. The results are shown in a graph in FIG. The ratio of the outer diameter of the central cylindrical portion to the outer diameter of the cylindrical portions at both ends of each roller is as follows. 1 roller: about 1.009, N
o. No. 2 roller: about 1.014, No. 3 rollers: about 1.
017, no. 4 rollers: about 1.020; 5 rollers: about 1.026; 6 rollers: about 1.032. Next, No. Three rollers were incorporated as transfer rollers in the image forming apparatus shown in FIG. At both ends of the transfer roller, a core metal having a diameter of 6 mm protrudes, and the protruding portion is pressed against the image forming body by a pressing force of 500 gf at each end by a spring. The nip width at both ends of the transfer roller was 2.0 mm, and the nip width at the center was 2.0 mm. Further, when a grayscale, solid black, and solid white image was printed in an environment at a temperature and a humidity of 15 ° C. and 10%, respectively, a good image was obtained.

Comparative Example 1 The polyurethane foam elastic material obtained in Production Example 1 was ground using the grindstone used in Example 1 to produce a cylindrical roller having an outer diameter of 16.0 mm. This roller was incorporated in the image forming apparatus as a transfer roller in the same manner as in Example 1. The nip width at both ends of the transfer roller was 2.5 mm, and the nip width at the center was 1.5 mm. When a grayscale, black solid, and white solid image was printed under the same conditions as in Example 1, poor transfer was observed at the center of the roller.

[0023]

According to the method of the present invention, a roller for an image forming apparatus which has a pseudo spindle type elastic layer and is used as a charging roller, a developing roller, a transfer roller, a toner supply roller, a cleaning roller, etc. is usually used. Can be efficiently manufactured by using a flat grindstone having a vertical edge portion used in the manufacture of a cylindrical roller.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus using an electrophotographic method.

FIG. 2 is a side view of an example of an image forming apparatus roller obtained by the method of the present invention.

FIG. 3 is an explanatory side view showing an example of a procedure for manufacturing a pseudo spindle roller of the present invention by grinding an elastic material using a flat grinding wheel having a vertical edge portion.

FIG. 4 shows the results obtained in Example 1 for No. 1; 1 to No. 6 is a graph showing an outer diameter at each position in a longitudinal direction of a pseudo spindle roller of No. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming body 2 Developing roller 3 Toner supply roller 4 Layer regulating blade 5 Transfer roller 6 Cleaning roller 7 Charging roller 8 Transfer material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 501 G03G 15/08 501D 21/10 21/00 312 F term (Reference) 2H003 BB11 CC05 2H032 AA05 BA19 2H034 AA02 AA06 BA00 BC01 BC03 2H077 AC04 AD06 DB14 FA22 3J103 AA01 AA72 BA31 EA03 FA02 FA15 FA18 GA02 GA52 GA64 GA73 GA74 HA03 HA05 HA12 HA15 HA18 HA20 HA32 HA33 HA37 HA45 HA46 HA48 HA53

Claims (7)

[Claims] 1. A method of manufacturing a roller having a pseudo spindle type elastic layer on the outer periphery of a rotation center axis by grinding an elastic material using a flat grinding wheel having a vertical edge portion, wherein the pseudo spindle type The elastic body layer has a central cylindrical portion, a tapered frustoconical portion of the same shape connected to both ends thereof, and an identical shape connected to both ends of each frustum portion and having a smaller diameter than the central cylindrical portion. A method of manufacturing a roller for an image forming apparatus, wherein the roller has a structure integrated with a cylindrical portion. 2. The method for manufacturing a roller for an image forming apparatus according to claim 1, wherein the outer diameter of the central cylindrical portion of the roller is 0.5 to 5% larger than the outer diameter of the cylindrical portions at both ends. 3. The ratio of the lengths of the central cylindrical portion, the two truncated cone portions, and the cylindrical portions at both ends of the roller is 1: 1.5 to 5.0: 0.8 to 3.
3. The method for manufacturing a roller for an image forming apparatus according to claim 1, wherein the value is 0. 4. The method for manufacturing a roller for an image forming apparatus according to claim 1, wherein the pseudo spindle type elastic layer is a conductive elastic layer. 5. An image forming apparatus comprising: a charging roller;
5. The method for manufacturing a roller for an image forming apparatus according to claim 1, wherein the roller is a developing roller, a transfer roller, a toner supply roller, or a cleaning roller. 6. The method according to claim 5, wherein the roller for the image forming apparatus is a transfer roller. 7. An image forming apparatus comprising a roller manufactured by the manufacturing method according to claim 1.