CN112305881A

CN112305881A - Developing roller and method for manufacturing the same

Info

Publication number: CN112305881A
Application number: CN202010430344.1A
Authority: CN
Inventors: 今瀬悠太
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2019-07-31
Filing date: 2020-05-20
Publication date: 2021-02-02
Also published as: JP2021026034A

Abstract

The invention provides a developing roller capable of forming an image with better image quality than the current state while maintaining a simple structure without a coating film and a manufacturing method thereof. The developing roller (1) is characterized in that the peak-to-peak density Spd for defining the surface shape of the outer peripheral surface (5) of the roller body (2) is 900000/mm in a surface roughness component composed of a plurality of concave-convex parts²Below, and 800/mm in a surface waviness component composed of a plurality of irregularities longer than the periodicity of the surface roughness component²The following. The manufacturing method comprises a step of polishing the outer peripheral surface (5) and then performing elastomer blast processing or laser processing to finish the outer peripheral surface into a surface shape satisfying the peak top density Spd.

Description

Developing roller and method for manufacturing the same

Technical Field

The present invention relates to a developing roller and a method of manufacturing the same.

Background

In an image forming apparatus using an electrophotographic method, a developing roller including a roller main body made of a crosslinked rubber is used. Various studies have been made on the surface shape of the outer peripheral surface of the roller body of the developing roller (patent documents 1 to 3, etc.).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2006-243374

[ patent document 2] Japanese patent laid-open publication No. 2013-73130

[ patent document 3] Japanese patent laid-open No. 2016-183997

Disclosure of Invention

[ problems to be solved by the invention ]

The invention aims to provide a developing roller capable of forming an image with better image quality than the current situation and a manufacturing method thereof.

[ means for solving problems ]

The invention provides a developing roller, comprising a roller body, wherein the outer peripheral surface of the roller body comprises: a surface roughness component comprising a plurality of irregularities and a surface waviness component comprising a plurality of irregularities having a longer periodicity than the surface roughness component, wherein a peak top density Spd defined in international Standardization organization standard iso (international Standardization organization)25178-2:2012 is 900000/mm in the surface roughness component²And 800/mm in the surface waviness component²The following.

Further, the present invention is a method for manufacturing a developing roller, the developing roller of the present invention is manufactured, and the manufacturing method includes: grinding the outer peripheral surface of the roller body; and a step of blasting the outer peripheral surface of the roll main body after polishing with an abrasive material comprising a composite of an elastomer and abrasive grains, and finishing the peak top density Spd to be within the range in the surface roughness component and the surface waviness component.

Further, the present invention is a method for manufacturing a developing roller, the method including: grinding the outer peripheral surface of the roller body; and a step of performing laser processing on the outer peripheral surface of the roller body after polishing, and finishing the peak density Spd in the surface roughness component and the surface waviness component to the range.

[ Effect of the invention ]

According to the present invention, a developing roller capable of forming an image having an image quality superior to that of the current state and a method for manufacturing the same can be provided.

Drawings

Fig. 1 is a perspective view showing an example of an embodiment of a developing roller of the present invention.

[ description of symbols ]

1: developing roller

2: roller body

3: through hole

4: shaft

5: peripheral surface

6: and (5) oxidizing the film.

Detailed Description

The outer peripheral surface of the roller main body is usually coated with a coating film after polishing, for example, in order to adjust the surface state.

The coating film is formed by applying a liquid coating agent as a base thereof to the outer peripheral surface of the roller body by a coating method such as a spraying method or a dipping method and then drying the coating agent.

However, the coating film has various problems such as mixing of foreign matters such as dust and generation of thickness unevenness, which are likely to occur during the formation.

Further, an organic solvent is required for preparing a coating agent, but the use of an organic solvent imposes a large burden on the environment, and the trend toward the formation of low Volatile Organic Compounds (VOC) is also being counter-acted in recent years.

The inventions described in patent documents 1 to 3 propose a method of polishing the outer peripheral surface of a roller body made of a crosslinked rubber product and finishing the outer peripheral surface to a predetermined surface shape by various kinds of machining.

With these configurations, it is considered that the structure of the roller body can be simplified by omitting the coating film.

However, according to the studies of the inventors, it is still impossible to say that the outer peripheral surface of the roller body is sufficiently uniformized and optimized in the surface shapes proposed in patent documents 1 to 3 at present.

In particular, when the coating film is omitted, the amount of toner that can be carried on the outer peripheral surface tends to vary, or the amount of toner tends to be insufficient, or conversely tends to be excessive.

If the amount of toner that can be carried on the outer peripheral surface varies, there is a concern that density unevenness occurs in the formed image, and if the amount of toner is insufficient, there is a concern that the density decreases, whereas if the amount of toner is excessive, there is a concern that so-called fogging occurs in a blank portion where the image is formed.

For example, the outer peripheral surface of a conventional roll main body finished by polishing has a surface shape in which a surface roughness component composed of a plurality of fine irregularities and a surface waviness component composed of a plurality of irregularities having a periodicity longer than that of the surface roughness component are superposed.

According to the studies of the inventors, it is important to control these components in order to uniformize and optimize the surface state of the outer peripheral surface of the roller body of the developing roller to the outer peripheral surface for the developing roller.

Therefore, the inventors have studied to find the number of projections (hills) per unit area in the unevenness constituting the surface roughness component and the surface waviness component, respectively, by using a new index of the surface shape.

As a result, it was found that the Product surface properties of international standardization organization standard ISO25178-2:2012 (GPS) -geometry Product Specifications of products-part 2: the peak top density Spd specified in the wording, definition and surface Property parameters "was 900000/mm in the surface roughness component²Hereinafter, the waviness component of the surface is 800/mm²The following may be used.

The peak top density Spd of the component with surface roughness exceeds 900000/mm²Or the peak top density Spd of the surface waviness component exceeds 800/mm²In any of the above cases, the amount of toner carried on the outer peripheral surface of the roller body is likely to be uneven.

Further, the amount of toner carried is not uniform, and thus the density of the formed image is not uniform, or the amount of toner carried on the outer peripheral surface is excessive, and thus fog is generated in a blank portion where the image is formed, or conversely, the amount of toner carried on the outer peripheral surface is insufficient, and thus the density of the formed image is reduced.

In contrast, by defining the peak top density Spd of the surface roughness component and the surface waviness component within the above ranges, it is possible to provide a developing roller capable of forming an image having an image quality superior to the current image while maintaining a simple structure in which a coating film is omitted.

That is, since the surface state of the outer peripheral surface is made uniform and optimized, it is possible to provide a developing roller in which density unevenness, reduction, fogging, and the like of an image to be formed are less likely to occur.

Further, in view of further improving the above effect, the peak top density Spd of the surface roughness component is preferably 600000/mm within the above range²Above, especially 670000/mm²Above, preferably 890000/mm²The following.

Further, the peak-to-peak density Spd of the surface waviness component is preferably 80/mm in the above range²Above, preferably 630/mm²The following.

In the present invention, the peak top density Spd of the surface roughness component and the surface waviness component is expressed by a value obtained by the following method in accordance with the ISO standard based on the result of measuring the surface shape of the outer peripheral surface of the roller body using, for example, a shape analysis laser microscope.

That is, in order to obtain the peak-to-peak density Spd of the surface roughness component, the number of peaks is counted after the curved surface correction is performed without using a filter or when the curved surface of the outer peripheral surface of the roller body is clearly observed with respect to the measurement result (original surface) within the predetermined observation area.

The number of peak tops counted was converted to the number per unit area (1 mm)²) The peak top density Spd (/ mm) of the surface roughness component²)。

In order to obtain the peak-to-peak density Spd of the surface waviness component, the measurement result (original surface) in a predetermined observation area is subjected to low-pass filter processing to remove a high-frequency component (surface roughness component), smoothed by a median filter, and then corrected for the plane inclination, thereby obtaining a measurement surface.

When the curved surface of the outer peripheral surface of the roller body is clearly observed, the curved surface is further corrected, and then the measurement area is obtained.

Then, the number of peak tops is counted in the measurement area, and the counted number of peak tops is converted into a per unit area (1 mm)²) The peak-to-peak density Spd (/ mm) of the surface waviness component²)。

The outer peripheral surface of the roller main body having the specific surface shape is not limited thereto, and for example, the arithmetic average height Sa defined in the ISO standard is preferably 0.5 μm or more, and preferably 2 μm or less.

The maximum height Sz defined in the ISO standard is preferably 8 μm or more, and preferably 16 μm or less.

Further, the depth of the concave portions constituting the irregularities of the surface waviness component is preferably 1 μm or more, and preferably 50 μm or less.

When the height direction dimension of the irregularities is smaller than these ranges, the amount of toner carried on the outer peripheral surface of the roller body may be insufficient, and the density of the formed image may be reduced.

On the other hand, when the height direction dimension of the irregularities is larger than the above range, the amount of toner carried on the outer peripheral surface of the roller main body may not be uniform, resulting in uneven density of an image to be formed, or the amount of toner carried on the outer peripheral surface may be excessive, resulting in fogging in a blank portion where an image is formed.

Developing roller and method for manufacturing the same

Fig. 1 is a perspective view showing an example of an embodiment of a developing roller 1 according to the present invention.

Referring to fig. 1, the developing roller 1 of this example includes a roller main body 2 formed in a non-porous single-layer cylindrical shape from a rubber composition to which conductivity is imparted. The shaft 4 is inserted through and fixed to the through hole 3 in the center of the roller body 2.

The shaft 4 is integrally formed of a material having good electrical conductivity, for example, a metal such as iron, aluminum, an aluminum alloy, or stainless steel.

The shaft 4 is electrically joined to the roller main body 2 through, for example, an electrically conductive adhesive and mechanically fixed thereto, or the shaft 4 having an outer diameter larger than the inner diameter of the through hole 3 is pressed into the through hole 3 and electrically joined to the roller main body 2 and mechanically fixed thereto.

In addition, the shaft 4 and the roller body 2 may be electrically joined and mechanically fixed by the above two methods in combination.

On the outer circumferential surface 5 of the roller body 2, an oxide film 6 is formed as enlarged in the drawing.

When the oxide film 6 is formed, the oxide film 6 functions as a dielectric layer, and the dielectric loss tangent of the developing roller 1 can be reduced. Further, the oxide film 6 can function as a low-friction layer, and adhesion of toner can be favorably suppressed.

Further, the oxide film 6 can be easily formed by simply oxidizing the rubber in the vicinity of the outer peripheral surface 5 by, for example, irradiating the outer peripheral surface 5 with ultraviolet rays or the like, and thus, a decrease in productivity of the developing roller 1 or an increase in manufacturing cost can be suppressed.

However, the oxide film 6 may be omitted.

The term "single layer" of the roller body 2 means that the number of layers made of rubber or the like is a single layer, and the extremely thin oxide film 6 formed by irradiation of ultraviolet rays or the like is not included in the number of layers.

In order to manufacture the developing roller 1, the rubber composition prepared is extruded into a cylindrical shape using an extruder, for example, and then cut into a predetermined length, and the rubber is crosslinked by applying pressure and heat in a vulcanizing tank.

Next, the crosslinked cylindrical body is heated in an oven or the like to be secondarily crosslinked, and after cooling, the outer peripheral surface 5 is polished so as to have a predetermined outer diameter (polishing step).

As the polishing method, various polishing methods such as dry longitudinal polishing can be used. Further, it is preferable that the outer circumferential surface 5 is finely polished at the end of the polishing step.

By performing the finish polishing, the peak top density Spd of the surface waviness component can be reduced, or the height-direction dimensions of the irregularities constituting the surface waviness component can be reduced.

The finish polishing may be mirror polishing using a polishing film.

In mirror polishing, the more precise the polishing film is used, the smaller the peak top density Spd of the surface waviness component or the smaller the height-direction dimension of the irregularities constituting the surface waviness component.

Next, the outer peripheral surface 5 after polishing is finished by sandblasting, laser processing, or the like to have a specific surface shape in which the peak top density Spd satisfies the above range in both the surface roughness component and the surface waviness component, thereby forming the roller body 2.

That is, only the outer peripheral surface 5 to be polished is in a state where the size in the height direction of fine irregularities constituting the surface roughness component is large and the number thereof is large.

When the outer peripheral surface 5 in the above-described state is further subjected to the blasting, the irregularities periodically longer than the surface roughness component, which constitute the surface waviness component, are left, and the irregularities finer than the irregularities constituting the surface roughness component can be selectively reduced and reduced.

In addition, in the case of laser processing, it is possible to reduce or reduce irregularities finer than those constituting the surface roughness component while newly forming irregularities periodically longer than those constituting the surface waviness component.

Further, the surface roughness component having a surface shape satisfying the above-mentioned specific requirement, that is, satisfying the peak top density Spd, can be 900000/mm²Below and 800/mm in the surface waviness component²The outer peripheral surface 5 in the following range.

As the blasting, elastomer blasting using an abrasive material (abrasive material) including a composite of an elastomer and abrasive grains is preferable.

Examples of the abrasive used for blasting the elastic body include a composite in which abrasive grains such as diamond, metal, and hard resin are fixed around the elastic body.

In a normal dry blasting process using an abrasive material entirely made of a hard material, the outer peripheral surface of the roller body tends to be excessively polished.

In addition, in the dry blasting, it is necessary to use a fine abrasive having a particle diameter of about several μm to several tens μm, but the fine abrasive is easily scattered and the output adjustment of the blasting is not easy.

On the other hand, in the wet blasting, not only scattering of the abrasive is easily suppressed, but also the residue of the abrasive is easily removed.

However, in the wet blasting, it is difficult to selectively reduce or reduce the fine irregularities constituting the surface roughness component while leaving large irregularities constituting the surface waviness component on the outer peripheral surface 5 of the roller body 2.

In contrast, in elastomer blasting using an abrasive material comprising a composite of an elastomer and abrasive grains, it is possible to selectively reduce the fine irregularities constituting the surface roughness component while utilizing the surface shape of the outer peripheral surface 5 of the roller body 2 formed in the polishing step before use.

That is, while large irregularities constituting the surface waviness component remain on the outer peripheral surface 5 of the roller body 2, minute irregularities constituting the surface roughness component can be selectively reduced and reduced.

Therefore, the outer peripheral surface 5 that satisfies the specific surface shape, which is difficult to form by dry blasting or wet blasting, can be formed.

In elastomer blasting, when the type and particle diameter of the abrasive, the pressure of spraying, and the like are fixed, the longer the spraying time is, the smaller the peak-to-peak density Spd of the surface roughness component can be made, or the larger the peak-to-peak density Spd of the surface waviness component can be made.

Alternatively, the height-direction dimension of the irregularities constituting the surface waviness component may be reduced.

The elastomer blasting depends on the particle diameter of the elastomer or abrasive grains constituting the abrasive material, and particularly, the peak-to-peak density Spd of the surface waviness component of the outer peripheral surface 5 is set to 550/mm in the above range²The aboveIn the case of (3), it can be suitably employed.

The laser processing is performed by, for example, irradiating the polished outer circumferential surface 5 with laser light whose irradiation size is limited to a predetermined irradiation size while moving the irradiation position at a predetermined pitch.

In the laser processing, the crosslinked material of the rubber composition forming the outer circumferential surface 5 is selectively melted by heat generated by irradiation of the laser, and at least a part thereof is evaporated.

As a result, a plurality of irregularities constituting the surface waviness component can be formed on the outer peripheral surface 5, and minute irregularities constituting the surface roughness component can be reduced.

In order to form the outer peripheral surface of the roller main body into the specific surface shape by laser processing, for example, the output of laser light, the irradiation size of laser light irradiated to the outer peripheral surface, the movement pitch of irradiation positions, the degree of overlapping of adjacent irradiation positions, or the like may be adjusted.

In the laser processing, for example, the peak top density Spd of the surface waviness component can be reduced as the movement pitch of the irradiation position is increased.

The pitch may be set in any range that can form a specific surface shape, but the pitch in the axial direction of the roller body is preferably 125 μm or less, particularly 110 μm or less.

The pitch in the circumferential direction of the roller body 2 is preferably 105 μm or less, particularly 95 μm or less.

The laser processing is performed particularly by setting the peak-to-peak density Spd of the surface waviness component of the outer peripheral surface 5 to less than 550/mm within the above range²In particular 450/mm²The following can be suitably employed.

The shaft 4 can be inserted and fixed in the through hole 3 at any time from the cutting of the cylindrical body to the finish machining.

However, after the cutting, the shaft 4 is preferably first subjected to secondary crosslinking, polishing, and finishing in a state of being inserted into the through hole 3.

This can suppress the bending or deformation of the roller body 2 caused by the expansion and contraction at the time of secondary crosslinking.

Further, by performing polishing and finish machining while rotating about the shaft 4, workability of the polishing and finish machining can be improved and the run-out of the outer peripheral surface 5 can be suppressed.

As described above, the shaft 4 may be inserted into the through hole 3 of the tubular body before the secondary crosslinking via an adhesive having conductivity, particularly a thermosetting adhesive having conductivity, and then the secondary crosslinking is performed, or a shaft having an outer diameter larger than the inner diameter of the through hole 3 may be press-fitted into the through hole 3.

In the former case, the thermosetting adhesive is cured while the cylindrical body is secondarily crosslinked by heating in the oven, and the shaft 4 is electrically and mechanically engaged with the roller body 2.

In the latter case, the electrical engagement and the mechanical fixation are completed simultaneously with the press-fitting of the shaft 4.

As described above, the shaft 4 and the roller body 2 may be electrically joined and mechanically fixed by the above-described two methods.

As described above, the oxide film 6 is preferably formed by irradiating the outer peripheral surface 5 of the roll main body 2 with ultraviolet rays.

That is, the outer peripheral surface 5 after being subjected to the blast processing or the laser processing as the finish processing is irradiated with ultraviolet rays of a predetermined wavelength for a predetermined time to oxidize the rubber in the vicinity of the outer peripheral surface 5, thereby forming the oxide film 6.

Therefore, the oxide film 6 can be formed in a simple and efficient manner, and a reduction in productivity of the developing roller 1 and an increase in manufacturing cost can be suppressed.

The oxide film 6 formed by the irradiation of ultraviolet rays does not cause a problem such as a coating film formed by coating a coating agent, and is excellent in uniformity of thickness, adhesion to the roll main body 2, and the like.

In view of forming the oxide film 6 having excellent functions by oxidizing the diene rubber in the rubber composition with good equivalent efficiency, the wavelength of the ultraviolet rays to be irradiated is preferably 100nm or more, preferably 400nm or less, and particularly 300nm or less.

The irradiation time is preferably 30 seconds or more, particularly 1 minute or more, preferably 30 minutes or less, particularly 20 minutes or less.

However, the oxide film 6 may be formed by another method or may not be formed.

Rubber composition

The rubber composition forming the roller body 2 is prepared by compounding a crosslinking ingredient or various additives for crosslinking the rubber in the rubber.

In order to impart conductivity to the rubber composition, the roller resistance value of the developing roller 1 is adjusted to be within an appropriate range, and the following description will be made of an ion-conductive rubber composition.

< rubber >

As described above, in order to impart ionic conductivity to the rubber composition, it is preferable to use an ionic conductive rubber as the rubber.

Further, as the rubber, it is preferable to use a diene rubber together with the ion conductive rubber.

By using the diene rubber in combination, it is possible to impart good processability to the rubber composition and to improve mechanical strength and durability of the roller body.

Further, by using the diene rubber in combination, the roll body can be provided with excellent properties as a rubber, that is, softness, small compression permanent strain, and resistance to collapse.

(ion-conductive rubber)

Examples of the ion conductive rubber include epichlorohydrin rubber and polyether rubber.

Examples of the epichlorohydrin rubber include epichlorohydrin homopolymers, epichlorohydrin-ethylene oxide binary copolymers (ECO), epichlorohydrin-propylene oxide binary copolymers, epichlorohydrin-allyl glycidyl ether binary copolymers, epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary copolymers (GECO), epichlorohydrin-propylene oxide-allyl glycidyl ether ternary copolymers, epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether quaternary copolymers, and epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether quaternary copolymers.

Examples of the polyether rubber include ethylene oxide-allyl glycidyl ether binary copolymers and ethylene oxide-propylene oxide-allyl glycidyl ether ternary copolymers.

Among these, ethylene oxide-containing copolymers, in particular ECO and/or GECO, are preferred.

The ethylene oxide content in the ECO and/or GECO is preferably 30 mol% or more, particularly 50 mol% or more, and preferably 80 mol% or less.

The ethylene oxide plays a role of reducing the roller resistance value of the developing roller.

However, if the ethylene oxide content is less than the above range, the above-described effect cannot be sufficiently obtained, and therefore, the roller resistance value of the developing roller may not be sufficiently reduced.

On the other hand, when the ethylene oxide content exceeds the above range, crystallization of ethylene oxide occurs, and the chain motion of the molecular chain is inhibited, so that the roller resistance value of the developing roller tends to be increased.

Further, the roller body after crosslinking becomes too hard, or the viscosity of the rubber composition before crosslinking at the time of heating and melting increases, and the processability of the rubber composition may be lowered.

The epichlorohydrin content in the ECO is the remainder of the ethylene oxide content.

That is, the epichlorohydrin content is preferably 20 mol% or more, preferably 70 mol% or less, and particularly 50 mol% or less.

The allyl glycidyl ether content in the GECO is preferably 0.5 mol% or more, particularly 2 mol% or more, preferably 10 mol% or less, particularly 5 mol% or less.

Allyl glycidyl ether functions to secure a free volume as a side chain, thereby playing a role of suppressing crystallization of ethylene oxide and reducing a roller resistance value of a developing roller.

However, if the allyl glycidyl ether content is less than the above range, the above effect cannot be sufficiently obtained, and therefore, the roller resistance value of the developing roller may not be sufficiently reduced.

On the other hand, allyl glycidyl ether functions as a crosslinking point at the time of crosslinking of GECO.

Therefore, when the allyl glycidyl ether content exceeds the above range, the crosslinking density of the GECO becomes too high, whereby the segmental motion of the molecular chain is inhibited, and the roller resistance value of the developing roller tends to be increased.

The epichlorohydrin content in the GECO is the remainder of the ethylene oxide content and the allyl glycidyl ether content.

That is, the epichlorohydrin content is preferably 10 mol% or more, particularly 19.5 mol% or more, preferably 69.5 mol% or less, particularly 60 mol% or less.

Further, as the GECO, in addition to the copolymer in the narrow sense of the above-described copolymerization of three monomers, a modified product obtained by modifying an epichlorohydrin-ethylene oxide copolymer (ECO) with allyl glycidyl ether is known.

In the present invention, any of the above-mentioned GECOs may be used.

One or two or more of these ion conductive rubbers may be used.

(diene rubber)

Examples of the diene rubber include natural rubber, Isoprene Rubber (IR), acrylonitrile butadiene rubber (NBR), Styrene Butadiene Rubber (SBR), Butadiene Rubber (BR), and Chloroprene Rubber (CR).

In particular, as the diene rubber, it is preferable to use both of CR and NBR in combination.

However, two or more kinds of rubbers may be used in combination.

·CR

CR functions to improve the flexibility of the roller body and improve the image durability of the developing roller.

The image durability is an index indicating how long the quality of an image formed can be maintained well while suppressing deterioration of the same toner when the toner is repeatedly used for image formation.

That is, only a very small part of the toner contained in the developing unit of the image forming apparatus is used in one image formation, and most of the remaining toner is repeatedly circulated in the developing unit.

Therefore, how much or no damage is caused to the toner by the roller body of the developing roller that is provided in the developing portion and that repeatedly contacts the toner is a key in improving the durability of the image.

When the flexibility of the roller main body is reduced and the image durability is reduced, the quality of the formed image tends to be gradually reduced in the repeated image formation.

Therefore, the developing roller is required to have excellent flexibility of the roller body in order to improve image durability.

CR functions to improve the charging characteristics of positively chargeable toner, or to finely adjust the roller resistance value of the developing roller because it is a polar rubber.

Further, CR is oxidized by irradiation with ultraviolet rays, and functions as a material for forming an oxide film on the outer circumferential surface of the roller main body.

CR is synthesized by emulsion polymerization of chlorobutadiene, and is classified into sulfur-modified type and non-sulfur-modified type according to the kind of molecular weight modifier used at this time.

Among them, sulfur-modified CR can be synthesized by plasticizing a polymer obtained by copolymerizing chloroprene and sulfur as a molecular weight modifier with thiuram disulfide or the like and adjusting the plasticized polymer to a predetermined viscosity.

Further, the non-sulfur-modified CR is classified into, for example, a thiol-modified CR and a xanthane-modified CR.

Among them, the thiol-modified CR is synthesized in the same manner as the sulfur-modified CR, except that alkylthiols such as n-dodecylthiol, t-dodecylthiol, and octylthiol are used as a molecular weight modifier.

Further, the xanthate-modified CR was synthesized in the same manner as the sulfur-modified CR, except that an alkylxanthate compound was used as a molecular weight modifier.

CR is classified into a slow crystallization rate type, a medium crystallization rate type, and a fast crystallization rate type based on its crystallization rate.

Any type of CR may be used in the present invention, but among them, a CR that is not sulfur-modified and has a slow crystallization rate is preferable.

Further, as CR, a copolymer of chloroprene and another copolymerization component may also be used.

Examples of other copolymerizable components include: 2, 3-dichloro-1, 3-butadiene, 1-chloro-1, 3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester, and the like.

Further, as CR, there are oil-filled CR in which filling oil is added to adjust flexibility and non-oil-filled CR in which filling oil is not added, but in the present invention, in order to prevent contamination of the photoreceptor, it is preferable to use non-oil-filled CR not containing filling oil that may become a bleeding substance.

One or two or more of these CR may be used.

·NBR

The NBR is still oxidized by the irradiation of ultraviolet rays, and functions as a material for forming an oxide film on the outer circumferential surface of the roller main body. Further, since the NBR is a polar rubber, it also functions to finely adjust the roller resistance value of the developing roller.

The NBR may be any of a low-nitrile NBR having an acrylonitrile content of 24% or less, a medium-nitrile NBR of 25% to 30%, a medium-nitrile NBR of 31% to 35%, a high-nitrile NBR of 36% to 42%, and a very high-nitrile NBR of 43% or more.

The NBR may be an oil-filled NBR in which an extender oil is added to adjust flexibility, or an oil-unfilled NBR in which an extender oil is not added.

One or two or more of these NBRs may be used.

(proportion of rubber)

The ratio of the rubber can be arbitrarily set according to various characteristics required for the developing roller, particularly, the roller resistance value, the flexibility of the roller body, and the like.

However, the proportion of the epichlorohydrin rubber plasma-conductive rubber is preferably 15 parts by mass or more, particularly 30 parts by mass or more, preferably 80 parts by mass or less, particularly 70 parts by mass or less, of the total 100 parts by mass of the rubber.

In the case where the ratio of the ion conductive rubber is less than the above range or exceeds the above range, in either case, the roller resistance value of the developing roller cannot be adjusted to a range suitable for the developing roller.

When the proportion of the ion conductive rubber exceeds the above range, the proportion of the diene rubber may be relatively small, and favorable characteristics as the rubber may not be imparted to the roller body.

On the other hand, by setting the ratio of the ion conductive rubber to the above range, the roller body can be provided with excellent characteristics as rubber while adjusting the roller resistance value of the developing roller to an appropriate range.

The proportion of the diene rubber is the residual amount of the ionic conductive rubber.

That is, when the proportion of the ion conductive rubber is set to a predetermined value within the above range, the proportion of the diene rubber may be set so that the total amount of the rubber becomes 100 parts by mass.

< crosslinking component >

As the crosslinking component, it is preferable to use a crosslinking agent for crosslinking the rubber and a crosslinking accelerator for accelerating crosslinking of the rubber by the crosslinking agent in combination.

Among these, examples of the crosslinking agent include a sulfur-based crosslinking agent, a thiourea-based crosslinking agent, a triazine derivative-based crosslinking agent, a peroxide-based crosslinking agent, and various monomers, and particularly, a sulfur-based crosslinking agent is preferable.

(Sulfur-based crosslinking agent)

Examples of the sulfur-based crosslinking agent include: powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, dispersible sulfur, or an organic sulfur-containing compound such as tetramethylthiuram disulfide or N, N-dithiodimorpholine, and the like, and sulfur is particularly preferable.

In view of imparting good properties as rubber to the roller body, the proportion of sulfur is preferably 0.5 parts by mass or more, and preferably 2 parts by mass or less, per 100 parts by mass of the total amount of rubber.

In the case where oil-treated powdered sulfur, dispersed sulfur, or the like is used as the sulfur, the above-mentioned ratio is a ratio of the sulfur itself as an effective component contained in each.

In the case where the organic sulfur-containing compound is used as the crosslinking agent, the proportion thereof is preferably adjusted so that the proportion of sulfur contained in the molecule with respect to 100 parts by mass of the total amount of the rubber falls within the above-mentioned range.

(crosslinking accelerator)

Examples of the crosslinking accelerator for accelerating crosslinking of the rubber include one or two or more of thiuram accelerators, thiazole accelerators, thiourea accelerators, guanidine accelerators, sulfenamide accelerators, and dithiocarbamate accelerators.

Among them, it is preferable to use a thiuram-based accelerator, a thiazole-based accelerator, a thiourea-based accelerator and a guanidine-based accelerator in combination.

The thiuram-based accelerator includes, for example, one or more of tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like, and tetramethylthiuram monosulfide is particularly preferable.

Examples of the thiazole accelerator include one or more of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, and 2- (4' -morpholinodithio) benzothiazole, and di-2-benzothiazolyl disulfide is particularly preferable.

As the thiourea-based accelerator, various thiourea compounds having a thiourea structure in the molecule can be used.

Examples of the thiourea-based accelerator include ethylenethiourea, N' -diphenylthiourea, trimethylthiourea, and compounds represented by formula (1):

(C_nH_2n+1NH)₂C＝S (1)

[ in the formula, n represents an integer of 1 to 12] and one or more of thiourea, tetramethylthiourea and the like, and ethylene thiourea is particularly preferable.

Examples of the guanidine-based accelerator include one or two or more of 1, 3-diphenylguanidine, 1, 3-di-o-tolylguanidine, 1-o-tolylbiguanidine, and the like, and 1, 3-di-o-tolylguanidine is particularly preferable.

In the above-described four-use system, the proportion of the thiuram-based accelerator is preferably 0.3 parts by mass or more, and preferably 1 part by mass or less, relative to 100 parts by mass of the total amount of the rubber, in view of the effect of accelerating crosslinking of the rubber, and the like.

The proportion of the thiazole accelerator is preferably 0.3 part by mass or more, and preferably 2 parts by mass or less, based on 100 parts by mass of the total amount of the rubber.

The proportion of the thiourea-based accelerator is preferably 0.3 parts by mass or more, and preferably 1 part by mass or less, relative to 100 parts by mass of the total amount of the rubber.

Further, the proportion of the guanidine-based accelerator is preferably 0.2 parts by mass or more, and preferably 1 part by mass or less, relative to 100 parts by mass of the total amount of the rubber.

The thiourea-based accelerator also functions as a crosslinking agent for ECO that does not have sulfur crosslinking properties, and the guanidine-based accelerator also functions as an accelerator for crosslinking ECO that is caused by the thiourea-based accelerator.

< conductive agent >

The rubber composition may further contain an ionic conductive agent.

By blending the ion conductive agent, the ion conductivity of the rubber composition can be further improved, and the roller resistance value of the developing roller 1 can be further reduced.

The ion conductive agent is preferably a salt (ionic salt) of an anion and a cation having a fluorine group and a sulfonyl group in the molecule.

Examples of the anion having a fluoro group and a sulfonyl group in the molecule, which constitutes the ionic salt, include one or two or more kinds of a fluoroalkyl sulfonate ion, a bis (fluoroalkylsulfonyl) imide ion, a tris (fluoroalkylsulfonyl) methide ion, and the like.

Among them, as the fluoroalkyl sulfonate ion, for example, CF is cited₃SO₃ ^-、C₄F₉SO₃ ^-And the like, or two or more thereof.

Further, the bis (fluoroalkylsulfonyl) imide ion may be, for example, (CF)₃SO₂)₂N^-、(C₂F₅SO₂)₂N^-、(C₄F₉SO₂)(CF₃SO₂)N^-、(FSO₂C₆F₄)(CF₃SO₂)N^-、(C₈F₁₇SO₂)(CF₃SO₂)N^-、(CF₃CH₂OSO₂)₂N^-、(CF₃CF₂CH₂OSO₂)₂N^-、(HCF₂CF₂CH₂OSO₂)₂N^-、[(CF₃)₂CHOSO₂]₂N^-And the like, or two or more thereof.

Further, the tris (fluoroalkylsulfonyl) methide ion may be, for example, (CF)₃SO₂)₃C^-、(CF₃CH₂OSO₂)₃C^-And the like, or two or more thereof.

Examples of the cation include one or more of alkali metal ions such as sodium, lithium, and potassium, ions of group 2 elements such as beryllium, magnesium, calcium, strontium, and barium, ions of transition elements, cations of amphoteric elements, quaternary ammonium ions, and imidazolium cations.

As the ionic salt, a lithium salt using a lithium ion as a cation, or a potassium salt using a potassium ion is particularly preferable.

Among them, (CF) is preferable in terms of the effect of improving the ionic conductivity of the rubber composition and reducing the resistance value of the outer layer₃SO₂)₂NLi [ lithium bis (trifluoromethanesulfonyl) imide]And/or (CF)₃SO₂)₂NK [ Potassium bis (trifluoromethanesulfonyl) imide]。

The proportion of the ionic conductive agent such as an ionic salt is preferably 0.5 parts by mass or more, and preferably 5 parts by mass or less, relative to 100 parts by mass of the total amount of the rubber.

< Others >

Various additives may be further compounded in the rubber composition as required. Examples of additives include: crosslinking aids, acid-absorbing agents, fillers, plasticizers, processing aids, deterioration inhibitors, and the like.

Among them, examples of the crosslinking assistant include: metal compounds such as zinc oxide (zinc white); one or more of fatty acids such as stearic acid, oleic acid, and cottonseed fatty acid, and other known crosslinking aids.

The proportion of the crosslinking assistant is preferably 0.1 part by mass or more, and preferably 7 parts by mass or less, respectively, based on 100 parts by mass of the total amount of the rubber.

The acid-absorbing agent functions to prevent chlorine-containing gas generated from epichlorohydrin rubber, CR, or the like during crosslinking from remaining in the roller body, or to prevent crosslinking inhibition or contamination of the photoreceptor due to chlorine-containing gas.

As the acid acceptor, various substances which function as acid acceptors can be used, but among them, hydrotalcite and magarat (magaraat) having excellent dispersibility are preferable, and hydrotalcite is particularly preferable.

Further, when hydrotalcite or the like is used in combination with magnesium oxide or potassium oxide, a higher acid absorption effect can be obtained, and contamination of the photoreceptor or the like can be more reliably prevented.

The proportion of the acid scavenger is preferably 0.2 parts by mass or more, particularly 0.5 parts by mass or more, and preferably 7 parts by mass or less, per 100 parts by mass of the total amount of the rubber.

Examples of the filler include one or more of zinc oxide, silica, carbon black, talc, calcium carbonate, magnesium carbonate, and aluminum hydroxide.

The mechanical strength of the roll body can be improved by blending the filler.

Further, by using conductive carbon black as a filler, electron conductivity can be imparted to the roller body.

Examples of the conductive carbon black include acetylene black.

The proportion of the conductive carbon black is preferably 1 part by mass or more, and preferably 30 parts by mass or less, relative to 100 parts by mass of the total amount of the rubber.

Examples of the plasticizer include various plasticizers such as dibutyl phthalate, dioctyl phthalate, and tricresyl phosphate, and various waxes such as polar waxes.

Examples of the processing aid include fatty acid metal salts such as zinc stearate.

The proportion of the plasticizer and/or the processing aid is preferably 3 parts by mass or less with respect to 100 parts by mass of the total amount of the rubber.

Examples of the deterioration inhibitor include various antioxidants and antioxidants.

The aging inhibitor plays a role of reducing environmental dependency of the roller resistance value of the developing roller and suppressing an increase in the roller resistance value when continuously energized.

Examples of the age resister include nickel diethyldithiocarbamate and nickel dibutyldithiocarbamate.

The proportion of the antioxidant is preferably 0.1 part by mass or more, and preferably 1 part by mass or less, per 100 parts by mass of the total amount of the rubber.

Further, as the additive, various additives such as a scorch retarder, a lubricant, a pigment, an antistatic agent, a flame retardant, a neutralizer, a nucleating agent, a co-crosslinking agent, and the like may be further blended at an arbitrary ratio.

In the example of fig. 1, the roller body 2 has a single-layer structure, but the roller body 2 may have a laminated structure of two or more layers.

The roller body 2 is not limited to a roller body formed of a rubber composition containing the above-described components. For example, the roller body 2 may be formed of various materials satisfying requirements that an appropriate roller resistance value can be imparted to the developing roller 1, the roller body 2 having excellent mechanical strength and durability can be formed, and characteristics that the roller body 2 is soft, has a small compression permanent strain, and is less likely to collapse can be imparted.

In either case, by forming the outer peripheral surface 5 of the roller main body 2 into the specific surface shape, the surface state of the outer peripheral surface 5 is made uniform and optimized more than it is, while maintaining a simple structure in which a coating film is omitted, and therefore, the developing roller 1 in which density unevenness, reduction, fogging, and the like of an image to be formed are less likely to occur can be obtained.

The developing roller 1 of the present invention can be used in an image forming apparatus using an electrophotographic method, such as a laser printer, an electrostatic copier, a plain paper facsimile machine, and a multifunction machine thereof.

[ examples ]

The present invention will be further described below based on examples and comparative examples, but the constitution of the present invention is not necessarily limited to these examples.

The peak-to-peak density Spd, the arithmetic mean height Sa, and the maximum height Sz of the surface roughness component and the surface waviness component of the outer peripheral surface of the roller body of the developing roller manufactured in examples and comparative examples are represented by values obtained by the following methods.

< Peak Density of surface roughness component Spd >

For VK-X150/160 manufactured by using a shape-resolving laser microscope (Keyence) (Strand)]In the observation area: 55625 μm²The number of peaks is counted without using a filter on the measurement result (original area) of the surface shape of the outer peripheral surface measured within the range of (1).

However, when the curved surface of the outer peripheral surface of the roller body is clearly observed, the number of peaks is counted after the curved surface correction is performed.

The number of peak tops counted was converted to the number per unit area (1 mm)²) Peak top density of surface roughness componentSpd(/mm²) The peak top density Spd was 900000/mm²The following evaluation was "O", and the evaluation was more than 900000/mm²Evaluation was "x".

< Peak Density of surface waviness component Spd >

The measurement result (original surface) of the surface shape of the outer peripheral surface measured by the shape analysis laser microscope was processed by a 25 μm low-pass filter to remove high-frequency components (surface roughness components), smoothed by a median filter (3 × 3), and further corrected for the plane inclination, to obtain a measurement surface.

The peak-to-peak density Spd of the waviness component was set to 800/mm²The following evaluation was "O", and the evaluation was more than 800/mm²Evaluation was "x".

< arithmetic mean height Sa and maximum height Sz >

According to the observation area using the shape-resolving laser microscope: 55625 μm²The arithmetic average height Sa and the maximum height Sz are obtained as the measurement result (original surface) of the surface shape of the outer peripheral surface measured in the range of (1).

< example 1 >

(preparation of rubber composition)

As the rubber, 15 parts by mass of ECO [ epsilorma (epichllomer) (registered trademark) D, EO/EP 61/39 (molar ratio) manufactured by OSAKA dada (OSAKA SODA) (stock.), 15 parts by mass of eico [ epiron (epilon) (registered trademark) 301 (low Vis type) manufactured by GECO [ OSAKA dada (OSAKA SODA) (stock.), 45 parts by mass of EO/EP/AGE ═ 73/23/4 (molar ratio) ], 10 parts by mass of shorelin (shocrene) (registered trademark) WRT and non-oil-extended ] manufactured by CR [ showa and electrician (stock ], and NBR [ Jokuyaya (JSR) (stock) ] N250SL, low-nitrile NBR, acrylonitrile content: 20% and non-oil-extended ]30 parts by mass.

Then, the following ingredients were blended and kneaded while masticating 100 parts by mass of the total of the four types of rubber using a banbury mixer.

[ Table 1]

Composition (I)	Mass portion of
		Ionic salts	3.40
Crosslinking aid	5.00
		Acid-absorbing agent	5.00
Filler	2.00
		Processing aid	1.00
Anti-aging agent	0.50

The components in table 1 are as follows. In addition, the mass part in the table is relative to the total amount of rubber 100 mass parts of mass.

Ionic salt: potassium bis (trifluoromethanesulfonyl) imide [ K-TFSI, EF-N112 manufactured by Mitsubishi Material Electron Synthesis (Strand) ]

Crosslinking assistant agent: zinc oxide made by Sakai chemical industry (Strand)

Acid-absorbing agent: hydrotalcite (DHT-4A (registered trademark) -2 manufactured by Kyowa chemical industry (Strand)

Filling agent: conductive carbon BLACK [ acetylene BLACK, superconducting acetylene BLACK (DENKA BLACK) (registered trademark) manufactured by the electrochemical industry (Strand), granular ]

Processing aid: zinc stearate [ Sakai made by chemical industry (steam) SZ-2000]

Anti-aging agent: nickel dibutyldithiocarbamate [ Noclark (Nocrac) (registered trademark) NBC manufactured by Innova chemical industry (David Co., Ltd.) ]

Subsequently, while continuing the kneading, the following crosslinking components were blended and further kneaded to prepare a rubber composition.

[ Table 2]

Composition (I)	Mass portion of
		Dispersible sulfur	1.50
Accelerant TS	0.50
		Accelerator DM	1.50
Accelerator 22	0.60
		Accelerant DT	0.54

The components in table 2 are as follows. In addition, the mass part in the table is relative to the total amount of rubber 100 mass parts of mass.

Dispersive sulfur: crosslinking agent [ crane, trade name Suforai (SULFAX) PS manufactured by chemical industry (stock.), sulfur component: 99.5% ]

Accelerator TS: tetramethylthiuram monosulfide [ SANCELER (registered trademark) TS manufactured by Sanxin chemical industries (Ltd.), thiuram series accelerator ]

Accelerator DM: di-2-benzothiazolyl disulfide [ Noccelar (registered trademark) DM, thiazole-based accelerator, manufactured by Noccelar (R) chemical industry, Innova chemical industries, Ltd ]

Accelerator 22: ethylene thiourea [ 2-mercaptoimidazoline, Abserve (acell) 22-S, thiourea accelerator, produced by Chuankou chemical industry (Strand) ]

Accelerator DT: 1, 3-di-o-tolylguanidine [ Su xi le (SANCELER) DT, guanidine-based accelerator manufactured by Sanxin chemical industries (Ltd.) ]

(production of developing roller)

The prepared rubber composition was fed to an extruder, extruded into a cylindrical shape having an outer diameter of 14.0mm and an inner diameter of 6.5mm, cut and attached to a temporary shaft for crosslinking, and crosslinked at 160 ℃ for 1 hour in a vulcanizing tank.

Subsequently, the crosslinked tubular body was mounted on a metal shaft having an outer diameter of 6.0mm and coated with a conductive thermosetting adhesive (polyamide-based) on the outer peripheral surface thereof, heated to 160 ℃ in an oven, and then bonded to the metal shaft, and then both ends were reshaped.

Next, the outer peripheral surface of the cylindrical body was longitudinally polished using a cylindrical grinder, and then mirror-polished using a #1000 polishing film [ a mirror film (registered trademark) manufactured by triax chemistry (jet), as finish polishing, to finish the outer diameter to phi 13.00 mm.

Next, after the polished outer peripheral surface was wiped with alcohol, the outer peripheral surface was subjected to elastomer blast processing.

As the abrasive, a composite of an elastomer having a particle size of several mm and diamond particles having a particle size of #3000 (about 0.3 μm) as abrasive grains was used.

The elastomer blast processing was performed under conditions that the pressure of the abrasive material spray was 0.5MPa and the time was 300 seconds.

After alcohol wiping was performed again on the outer peripheral surface after elastomer blasting, the outer peripheral surface was set to a distance of 50mm from the UV light source, set in a UV treatment apparatus, and irradiated with ultraviolet light for 15 minutes while rotating at 300rpm, thereby forming an oxide film, and a developing roller was manufactured.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 861198/mm²(. smallcircle.) and a surface waviness fraction of 626/mm²(. smallcircle.), the arithmetic average height Sa is 0.51 μm, and the maximum height Sz is 8.2 μm.

< example 2 >

A developing roller was produced in the same manner as in example 1, except that the spraying time of the abrasive in the elastomer blast processing was 60 seconds.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 874203/mm²(. smallcircle.) and a surface waviness of 560/mm²(. smallcircle.), the arithmetic average height Sa is 0.61 μm, and the maximum height Sz is 8.5. mu.m.

< example 3 >

A developing roller was produced in the same manner as in example 1, except that a #600 polishing film [ a mirror film produced by triax chemistry (strand) ] was used for mirror polishing and the time for spraying the polishing material in elastomer blasting was 600 seconds.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 888296/mm²(. smallcircle.) and a surface waviness fraction of 593/mm²(. smallcircle.), the arithmetic average height Sa is 0.99. mu.m, and the maximum height Sz is 11.7. mu.m.

< example 4 >

Using the same rubber composition as in example 1, the outer peripheral surface of the cylindrical body bonded to the metal shaft and having both ends shaped was subjected to dry longitudinal polishing using a cylindrical polishing machine, and then mirror polishing using a #1000 polishing film [ a mirror film (registered trademark) manufactured by trinsical chemical (jet) ] was performed as finish polishing, by the same procedure as in example 1, and the outer diameter was finished to phi 13.00 mm.

Next, after alcohol wiping of the polished outer peripheral surface, laser processing was performed using a laser beam machine [ fiber laser beam machine ML-7320DL manufactured by amantamiyagi (AMADA MIYACHI) (thigh) ]. The movement pitch of the irradiation position of the laser during laser processing is axial: 50 μm, circumferential direction: the output was adjusted to 45 μm by setting the degree of overlap between adjacent irradiation positions to 30%.

After alcohol wiping of the outer peripheral surface after laser processing was performed again, the outer peripheral surface was set to a distance of 50mm from the UV light source, set in a UV treatment apparatus, and irradiated with ultraviolet light for 15 minutes while rotating at 300rpm, thereby forming an oxide film, and a developing roller was manufactured.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 835851/mm²(. smallcircle.) and a surface waviness fraction of 430/mm²(. smallcircle.), the arithmetic average height Sa of 1.3 μm and the maximum height Sz of 13.9. mu.m.

< example 5 >

Except that the movement pitch of the irradiation position of the laser beam during laser processing is set as the axial direction: 55 μm, circumferential direction: a developing roller was produced in the same manner as in example 4, except that the thickness of the developing roller was 50 μm and the overlap degree of the adjacent irradiation positions was set to 30%, and the output was adjusted accordingly.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 698650/mm²(. smallcircle.) and a surface waviness component of 364/mm²(. smallcircle.), the arithmetic average height Sa of 1.2 μm and the maximum height Sz of 13.3 μm.

< example 6 >

Except that the movement pitch of the irradiation position of the laser beam during laser processing is set as the axial direction: 60 μm, circumferential direction: a developing roller was produced in the same manner as in example 4, except that the overlap of adjacent irradiation positions was set to 30% and the output was adjusted accordingly, to 60 μm.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 777631/mm²(. smallcircle.) and a surface waviness fraction of 342/mm²(. smallcircle.), the arithmetic average height Sa of 1.8 μm and the maximum height Sz of 13.7 μm.

< example 7 >

Except that the movement pitch of the irradiation position of the laser beam during laser processing is set as the axial direction: 70 μm, circumferential direction: a developing roller was produced in the same manner as in example 4, except that the overlap degree of the adjacent irradiation positions was set to 30% and the output was adjusted accordingly, to produce a developing roller of 65 μm.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 736808/mm²(. smallcircle.) and a surface waviness fraction of 182/mm²(. smallcircle.), the arithmetic average height Sa is 1.4 μm, and the maximum height Sz is 11.1. mu.m.

< example 8 >

Except that the movement pitch of the irradiation position of the laser beam during laser processing is set as the axial direction: 100 μm, circumferential direction: a developing roller was produced in the same manner as in example 4, except that the overlap of the adjacent irradiation positions was set to 30% and the output was adjusted accordingly, to 90 μm.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 679001/mm²(. smallcircle.) and a surface waviness fraction of 116/mm²(. smallcircle.), the arithmetic average height Sa is 1.2 μm, and the maximum height Sz is 11.7. mu.m.

< example 9 >

Except that the movement pitch of the irradiation position of the laser beam during laser processing is set as the axial direction: 120 μm, circumferential direction: a developing roller was produced in the same manner as in example 4, except that the overlap degree of the adjacent irradiation positions was set to 30% and the output was adjusted accordingly, to 100 μm.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 689231/mm²(. smallcircle.) and a surface waviness fraction of 83/mm²(. smallcircle.) and an arithmetic mean height Sa of 1.9. mu.m, and a maximum height Sz of 15.8 μm.

< comparative example 1 >

A developing roller was produced in the same manner as in example 4, except that the outer peripheral surface mirror-polished with the polishing film of #1000 was further mirror-polished with the polishing film of #3000 [ mirror film produced by triax chemical (strand) ], and laser processing was omitted.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 1135356/mm²(×) with a surface waviness content of 396/mm²(. smallcircle.), the arithmetic average height Sa is 0.4 μm, and the maximum height Sz is 10.9. mu.m.

< comparative example 2 >

A developing roller was produced in the same manner as in example 4, except that laser processing of the outer peripheral surface mirror-polished using the polishing film of #1000 was omitted.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 1082111/mm²(×) the surface waviness component was 1063/mm²(×), the arithmetic mean height Sa is 1.0 μm, and the maximum height Sz is 13.1. mu.m.

< comparative example 3 >

A developing roller was produced in the same manner as in example 4, except that mirror polishing and laser processing for the longitudinally polished outer circumferential surface were omitted.

The peak-to-peak density Spd of the outer peripheral surface of the roller body of the produced developing roller was a surface roughness component of 9297859/mm²(×) with a surface waviness content of 680/mm²(. smallcircle.), the arithmetic average height Sa of 2.1 μm and the maximum height Sz of 21.5. mu.m.

< practical machine test >

The developing rollers manufactured in examples and comparative examples were mounted in place of a genuine developing roller including a toner container for storing toner, a photoreceptor, and a developing roller in contact with the photoreceptor, and a new black toner cartridge detachably mounted on a main body of a color laser printer (HL-L8360 CDW manufactured by brother industries).

Then, the assembled ink cartridges were loaded into the color laser printer, 30 images of pure black and halftone (2 spaces per 1 dot) were formed successively, and the density of the first formed image was measured using a reflection densitometer (model 939 manufactured by alice (X-Rite)) and evaluated by the following criteria.

(pure black)

O: the concentration is more than 1.3. Is good.

And (delta): the concentration is 1.2 or more and less than 1.3. The middle level.

X: the concentration is less than 1.2. It is not good.

(halftone)

O: the concentration is above 0.65. Is good.

And (delta): the concentration is 0.6 or more and less than 0.65. The middle level.

X: the concentration is less than 0.6. It is not good.

(unevenness)

In addition, in 30 formed pure black images, even if unevenness in density was observed in one sheet, the image was evaluated as poor (x), and no unevenness was observed as good (o).

The results are shown in tables 3 to 6.

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

From the results of examples 1 to 9 and comparative examples 1 to 3 in tables 3 to 6, it is understood that the peak top density Spd of the outer peripheral surface of the roller body is 900000/mm in the surface roughness component²Below, and 800/mm in the surface waviness component²As described below, a developing roller capable of forming an image having an image quality superior to that of the current state while maintaining a simple structure in which a coating film is omitted can be obtained.

From the results of examples 1 to 3, it is found that in order to form the outer peripheral surface of the roller body into the above-described surface shape, it is effective to perform elastomer blast processing after mirror polishing.

Further, from the results of examples 4 to 9, it is understood that the outer peripheral surface can be formed into the surface shape by laser processing the outer peripheral surface of the roller body after mirror polishing.

Claims

1. A developing roller includes a roller body, an outer circumferential surface of the roller body including: a surface roughness component comprising a plurality of irregularities and a surface waviness component comprising a plurality of irregularities having a longer periodicity than the surface roughness component, wherein the peak top density Spd specified in International organization for standardization ISO25178-2:2012 is 900000/mm in the surface roughness component²And 800/mm in the surface waviness component²The following.

2. The developing roller according to claim 1, wherein the peak top density Spd is 670000/mm in the surface roughness component²Above and 890000/mm²The following.

3. The developing roller according to claim 1 or 2, wherein the peak-to-peak density Spd is 80/mm in the surface waviness component²Above 630/mm²The following.

4. The developing roller according to any one of claims 1 to 3, wherein the outer peripheral surface is constituted by a crosslinked product of rubber, including an oxide film.

5. A method of manufacturing a developing roller, the developing roller according to any one of claims 1 to 4 being manufactured, and the method of manufacturing a developing roller comprising:

grinding the outer peripheral surface of the roller body; and

and blasting the outer peripheral surface of the roll main body after polishing with an abrasive material including a composite of an elastic body and abrasive grains, and finishing the peak top density Spd to a predetermined range in the surface roughness component and the surface waviness component.

6. The method for manufacturing a developing roller according to claim 5, wherein the outer circumferential surface of the roller body is constituted by a crosslinked product of rubber, further comprising after the step of finishing

And irradiating the outer peripheral surface with ultraviolet rays to oxidize the rubber to form an oxide film.

7. A method of manufacturing a developing roller, the developing roller according to any one of claims 1 to 4 being manufactured, and the method of manufacturing a developing roller comprising:

grinding the outer peripheral surface of the roller body; and

and a step of performing laser processing on the outer peripheral surface of the roll main body after polishing, and finishing the peak density Spd to a predetermined range in the surface roughness component and the surface waviness component.

8. The method for manufacturing a developing roller according to claim 7, wherein the outer circumferential surface of the roller body is constituted by a crosslinked product of rubber, further comprising after the step of finishing