CN112904685A

CN112904685A - Developing roller

Info

Publication number: CN112904685A
Application number: CN202010417367.9A
Authority: CN
Inventors: 黒田贤一
Original assignee: Sumitomo Rubber Industries Ltd
Current assignee: Sumitomo Rubber Industries Ltd
Priority date: 2019-12-03
Filing date: 2020-05-18
Publication date: 2021-06-04
Also published as: JP2021089344A

Abstract

The invention provides a developing roller, which has a simple structure that the whole roller body is integrally formed by the same cross-linked product of rubber composition, and the abrasion of the end part is inhibited, so that the toner leakage is not easy to generate, and the image with good image quality can be formed. The developing roller (1) comprises a roller body (2) composed of a crosslinked product of a rubber composition containing 20 parts by mass or more and 50 parts by mass or less of a specific high-cis BR having a cis-1, 4 bond content of 97% or more out of 100 parts by mass of the total amount of epichlorohydrin rubber, CR and rubber.

Description

Developing roller

Technical Field

The present invention relates to a developing roller.

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. The end of the roller body is sealed with a seal member, but various studies have been made on the structure of the end in order to prevent wear caused by sliding connection with the seal member (patent document 1 and the like).

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open No. 2019-101374

Disclosure of Invention

[ problems to be solved by the invention ]

The invention aims to provide a developing roller which has a simple structure that the whole roller body is integrally formed by a cross-linked product of the same rubber composition, the abrasion of the end part is inhibited, the leakage of toner is not easy to generate, and images with good image quality can be formed.

[ means for solving problems ]

The present invention is a developing roller comprising a roller body integrally formed of a crosslinked product of a rubber composition, the rubber composition containing at least epichlorohydrin rubber, chloroprene rubber, and butadiene rubber having a cis-1, 4 bond content of 97% or more as rubbers, and a proportion of the butadiene rubber being 20 parts by mass or more and 50 parts by mass or less of 100 parts by mass of the total amount of the rubbers.

[ Effect of the invention ]

According to the present invention, it is possible to provide a developing roller having a simple structure in which the entire roller body is integrally formed from a crosslinked product of the same rubber composition, and in which abrasion of the end portion is suppressed, toner leakage and the like are less likely to occur, and an image having good image quality can be formed.

Drawings

Fig. 1 is a perspective view showing an overall appearance of an example of a developing roller according to 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

As described above, the developing roller of the present invention includes a roller body integrally formed of a crosslinked product of a rubber composition containing at least epichlorohydrin rubber, Chloroprene Rubber (CR), and Butadiene Rubber (BR) having a cis-1, 4 bond content of 97% or more (hereinafter, sometimes abbreviated as "specific high cis BR") as a rubber, and the proportion of the specific high cis BR is 20 parts by mass or more and 50 parts by mass or less of 100 parts by mass of the total amount of the rubber.

In development using a developing roller, the developing roller is provided in a developing portion of an image forming apparatus that accommodates toner, and the developing roller is rotated in a state where a tip end portion of a quantity regulating blade (charging blade) is brought into contact with an outer peripheral surface of a roller body of the developing roller.

In this way, the toner in the developing section is charged and adheres to the outer peripheral surface of the roller main body, and the amount of adhesion of the adhered toner is restricted when the toner passes through the nip portion between the outer peripheral surface of the roller main body and the tip end portion of the amount restricting blade, and a toner layer having a substantially constant thickness is formed on the outer peripheral surface.

In addition, an electrostatic latent image is formed by uniformly charging the surface of the photoreceptor at the same time and then exposing the surface to light.

Then, when the developing roller is further rotated in this state to convey the toner layer to the vicinity of the surface of the photoreceptor, the toner forming the toner layer selectively moves to the surface of the photoreceptor in accordance with the electrostatic latent image formed on the surface of the photoreceptor, and the electrostatic latent image is developed into a toner image.

In order to prevent the toner adhering to the outer peripheral surface of the roller body from leaking out of the developing portion, the axial end portion of the roller body of the developing roller is normally sealed by the sealing member as described above.

The sealing member is formed of, for example, felt, and is slidably connected to an outer peripheral surface of an end portion of the rotating developing roller in the axial direction of the roller body in a state fixed to a frame of the developing unit or the like.

However, when the conventional developing roller repeats image formation, toner may leak from the end portion to be sealed by the sealing member.

The leakage of toner is caused by the repetition of image formation, and the outer peripheral surface of the sealing member in sliding contact with the end portion of the roller body in the axial direction is worn away to generate a gap with the sealing member.

Therefore, as described in patent document 1, various studies have been made on, for example, coating the end portion of the roller main body, which is slidably connected to the seal member, with a coating layer made of a hard resin or the like, and improving the wear resistance of the roller main body as compared with the intermediate portion contributing to image formation.

However, when these measures are taken, the entire structure of the roller body becomes complicated, and the number of production steps and the number of forming materials increase, which causes problems such as reduction in productivity of the developing roller and increase in production cost.

Further, the coating layer may be peeled off or abraded, and the function of improving the abrasion resistance may be lost in a relatively short time, and toner leakage may occur due to abrasion of the end portion.

In contrast, according to the present invention, as described above, the entire roller body is integrally formed from a cured product of a rubber composition containing a specific high cis BR in a proportion of 20 parts by mass or more in 100 parts by mass of the total amount of rubber.

The specific high-cis BR has higher rubber hardness after hardening and is superior in abrasion resistance to ordinary BR having a cis-1, 4 bond content of less than 97%.

Therefore, the roller body can be configured to have a simple structure in which the coating layer is not formed at the end portion, that is, the coating layer and the like are removed, and the abrasion resistance of the end portion can be improved to suppress the occurrence of toner leakage for a long period of time.

Further, according to the present invention, the specific high-cis BR may be used in combination with the rubber in an amount of 50 parts by mass or less based on 100 parts by mass of the total amount of the rubber, and particularly, appropriate flexibility may be imparted to the roll body by the flexibility of CR.

Therefore, it is possible to continuously form an image having good image quality without image defects for a long period of time from the initial stage of image formation.

Rubber composition

The rubber composition which is the base of the roller body of the developing roller of the present invention contains at least epichlorohydrin rubber, CR and specific high-cis BR as rubbers as described above.

< specific high cis BR >

Among these, as the specific high-cis BR, BR having a cis-1, 4 bond content of 97% or more, particularly 98% or more as described above can be selected from various types of BR having a crosslinking property and containing a butadiene-containing polymer.

Further, as the specific high-cis BR, there are oil-extended specific high-cis BR to which extender oil is added to adjust flexibility and non-oil-extended specific high-cis BR to which extender oil is not added, but in the present invention, in order to prevent contamination of the photoreceptor, non-oil-extended specific high-cis BR which does not contain extender oil that may be a bleeding substance is preferable.

Specific examples of the non-oil-extended specific high-cis BR are not limited thereto, and include, for example, one or two or more of the following various products.

BR150[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1% ], BR150B [ cis-1, 4 bond content: 97%, trans-1, 4 bond content: 2%, 1,2 bond content: 1% ], BR150L [ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1% ], BR360L [ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1% ], BR230[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1% ].

In addition, a specific high cis-BR having a cis-1, 4 bond content in the above range may be used as the matrix polymer, and a polymer alloy compounded with a highly crystalline Syndiotactic Polybutadiene resin (SPB) may be used as the specific high cis-BR.

Specific examples of the polymer alloy are not limited to these, and include one or two or more of the following various products.

The n-hexane-insoluble component in the following examples indicates the amount of SPB crystals in the matrix polymer.

VCR412[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1%, n-hexane-insoluble component: 12.0% ], VCR617[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1%, n-hexane-insoluble component: 17.0% ], VCR450[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1%, n-hexane-insoluble component: 3.8% ], VCR800[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1%, n-hexane-insoluble component: 5.3% ]

One or more of these specific high-cis BR may be used.

< Epichlorohydrin 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.

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.

As the epichlorohydrin rubber, GECO is particularly preferable.

Since GECO has a double bond in the main chain functioning as a crosslinking point due to allyl glycidyl ether, the compression set after crosslinking can be reduced by crosslinking between the main chains.

Therefore, the compression set of the roller body can be made small and the collapse is not easily generated.

One or two or more of these epichlorohydrin rubbers may be used.

＜CR＞

CR functions to improve flexibility of the roller body and maintain image quality of a formed image.

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, it is still preferable to use non-oil-filled CR not containing filling oil that may become a bleeding substance in order to prevent contamination of the photoreceptor.

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

< other rubbers >

As the rubber, in addition to epichlorohydrin rubber, CR and specific high cis BR3 kinds, can further use other rubber.

Examples of the other rubber include BR other than the specific high-cis BR, that is, BR having a cis-1, 4 bond content of less than 97% and a crosslinking property, acrylonitrile butadiene rubber (NBR), and the like.

However, in view of further improving the effect of the present invention, it is preferable to select and use only a specific high-cis BR as the BR, that is, a BR having a total amount of the specific high-cis BR and not including (excluding) other BRs.

(NBR)

The NBR has a dissolution parameter (SP value) close to that of any of specific high-cis BR, epichlorohydrin rubber and CR, and therefore functions as a so-called compatibilizer for these rubbers to assist in the micro dispersion between the respective rubbers and improve the integrity of the rubber composition.

Further, the rubber composition functions to improve the fluidity during heating and to ensure good moldability.

The NBR also functions to further improve flexibility of the roller body, improve image quality of formed images, or improve the elastic modulus of the outer peripheral surface of the roller body.

The NBR 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, 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.

The NBR may be any of a low-nitrile NBR having a bonded acrylonitrile amount 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.

In addition, as the NBR, it is preferable to select NBR having a low mooney viscosity in order to improve the fluidity of the rubber composition during heating and to obtain better moldability even when the rubber composition is prepared without a softener.

In particular, Mooney viscosity ML of NBR₍₁₊₄₎The temperature of 100 ℃ is preferably 35 or less.

However, the lower limit of the mooney viscosity is not particularly limited, and NBR of various solids up to NBR of the minimum mooney viscosity that can be obtained can be used.

Alternatively, a liquid NBR that is liquid at room temperature may be used instead of the solid NBR.

Furthermore, as the solid NBR, there are oil-filled NBR in which the flexibility is adjusted by adding an extender oil, and non-oil-filled NBR in which the extender oil is not added, but in the present invention, it is preferable that the non-oil-filled NBR does not contain the extender oil which may be a bleeding substance in order to prevent contamination of the photoreceptor.

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

< proportion of rubber >

The specific high cis-BR ratio is, for example, 20 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the total amount of the rubber as described above.

The reason for this is as described above.

In view of further improving the effect of the present invention, the proportion of the specific high-cis BR is preferably 35 parts by mass or more, and preferably 45 parts by mass or less, in particular, out of 100 parts by mass of the total amount of the rubber, within the above range.

The proportion of the epichlorohydrin rubber is preferably 30 parts by mass or more, and preferably 60 parts by mass or less, out of 100 parts by mass of the total amount of the rubber.

In the case where the proportion of the epichlorohydrin 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 epichlorohydrin rubber exceeds the above range, the proportion of CR and/or NBR may be relatively low, and favorable characteristics as the rubber may not be imparted to the roller body.

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

The ratio of CR and/or NBR is the residual amount of the specific high cis BR and epichlorohydrin rubber.

That is, when the proportions of the specific high-cis BR and epichlorohydrin rubber are set to predetermined values within the above ranges, the CR and/or NBR may be set so that the total amount of the rubber is 100 parts by mass.

< crosslinking component >

A crosslinking component for crosslinking a rubber is blended in a rubber composition.

As the crosslinking component, it is preferable to use a crosslinking agent for crosslinking the rubber in combination with a so-called crosslinking accelerator having a function of adjusting crosslinking of the rubber by the crosslinking agent.

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 organic sulfur-containing compounds such as 4,4' -dithiodimorpholine and tetramethylthiuram disulfide.

Particularly preferably, 4' -dithiodimorpholine is used in combination with sulfur.

4,4' -dithiodimorpholine is a cross-linking agent with a 2-stage cross-linking mechanism: the rubber composition is decomposed at a crosslinking temperature to release active sulfur, and the rubber is crosslinked by the released active sulfur, whereby the rapid crosslinking of the rubber composition can be suppressed as compared with the case where sulfur is directly formulated as a crosslinking agent.

Therefore, the use of 4,4' -dithiodimorpholine in combination with sulfur has the following advantages: for example, even in an environment where burning is likely to occur, the generation of scorch can be suppressed, and the waste of the rubber composition can be reduced as much as possible.

The proportion of 4,4' -dithiodimorpholine in the combined system 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.

The proportion of sulfur is preferably 0.3 part by mass or more, and preferably 1 part by mass or less, based on 100 parts by mass of the total amount of the rubber.

(crosslinking accelerator)

Examples of the crosslinking accelerator 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-mentioned four-component 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, per 100 parts by mass of the total amount of the rubber, in view of the effect of adjusting the crosslinking of the rubber, and the like.

The proportion of the thiazole-based accelerator is preferably 0.3 part 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 proportion of the thiourea-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.

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.

< 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; 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, 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.

Carbon black such as thermal carbon black is particularly preferable as the filler.

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.

Development roller

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

Referring to fig. 1, the developing roller 1 of this example includes a roller main body 2 formed of a rubber composition containing the above-described components and formed in a non-porous single-layer cylindrical shape, and a shaft 4 is inserted and fixed into a through hole 3 in the center of the roller main 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.

An oxide film 6 may be formed on the outer circumferential surface 5 of the roller body 2 as shown in an enlarged view.

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, by forming the oxide film 6 as a low-friction layer, particularly, the abrasion resistance of the end portion can be further improved, and further, the occurrence of toner leakage can be suppressed for a long period of time, or the adhesion of toner when used as a developing roller can be suppressed.

Further, since the oxide film 6 can be formed simply by, for example, irradiating ultraviolet rays or the like, it is possible to suppress a decrease in productivity of the developing roller 1 or an increase in manufacturing cost.

However, the oxide film 6 may not be formed.

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

< production of developing roller >

In order to manufacture the developing roller 1, the rubber composition containing the above components is first extruded into a cylindrical shape using an extrusion molding machine, then cut into a predetermined length, and crosslinked by pressurizing and heating with pressurized steam in a vulcanizing tank.

Next, the crosslinked cylindrical body is heated in an oven or the like to be secondarily crosslinked and then cooled, and is polished so as to have a predetermined outer diameter, thereby forming the roller body 2.

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

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

This can suppress warpage, deformation, and the like of the cylindrical body due to expansion and contraction during secondary crosslinking.

Further, by polishing while rotating about the shaft 4, the polishing workability 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 the shaft 4 having an outer diameter larger than the inner diameter of the through hole 3 may be pressed 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 joining and the mechanical fixing are completed simultaneously with the press-fitting.

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 of the roll body 2 is irradiated with ultraviolet rays of a predetermined wavelength for a predetermined time to oxidize the diene rubber in the rubber composition constituting 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 decrease in productivity of the developing roller 1 or an increase in manufacturing cost can be suppressed.

Further, the oxide film 6 formed by the irradiation of ultraviolet rays does not cause problems such as peeling and abrasion, for example, as in the case of a coating layer formed by applying a coating agent, and is excellent in uniformity of thickness, adhesion to the roller main body 2, and the like.

In view of efficiently oxidizing the diene rubber in the rubber composition to form the oxide film 6 having an excellent function, the wavelength of the ultraviolet light 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.

In the embodiment of fig. 1, the roller body 2 has a single-layer structure composed of a crosslinked product of the rubber composition of the present invention containing the above-mentioned components, but the roller body may have a laminated structure of 2 or more layers.

In this case, the outermost layer constituting the laminated structure may be formed of a crosslinked product of the rubber composition of the present invention containing the above-mentioned components.

The developing roller of the present invention can be suitably 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.

< example 1 >

(preparation of rubber composition)

As the rubber, 60 parts by mass of Eikon (EPION) (registered trademark) 301 (low Vis type) manufactured by GECO [ OSAKA SODA (stock), EO/EP/AGE ═ 73/23/4 (molar ratio) ], 10 parts by mass of Shorelin (SHOPRENE) (registered trademark) WRT manufactured by CR [ showa and electrician (stock), non-oil-extended ]10 parts by mass, NBR [ nibo (nibo) (registered trademark) DN401LL manufactured by japan ryton (ZEON) (stock), low nitrile NBR, and bound acrylonitrile amount (central value): 18.0%, non-oil-extended ]10 parts by mass and specific high cis BR [ euplol (UBEPOL) BR150B, cis-1, 4 bond content manufactured by yushu, prosperous (stock) as set forth above: 97%, trans-1, 4 bond content: 2%, 1,2 bond content: 1% and non-oil-extended ]20 parts by mass.

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

[ Table 1]

Composition (I)	Mass portion of
		Crosslinking aid	2.5
Acid-absorbing agent	3.0
		Filler	1.0

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.

Crosslinking assistant agent: two kinds of zinc oxide (three-well metal mining industry (stock) manufacture)

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

Filling agent: carbon Black [ thermal carbon Black, Asahi #15 manufactured by Asahi carbon Black (stock) ]

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
		Crosslinking agents I	0.60
Crosslinking agent II	0.55
		Accelerant TS	0.50
Accelerator DM	0.50
		Accelerator 22	0.30
Accelerant DT	0.28

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.

A crosslinking agent I: oil-treated powdered sulfur [ crane see chemical industry (stock) made golden print 5% oil-immersed micropowder sulfur ]

A crosslinking agent II: 4,4' -Didithiodimorpholine [ Barunock (VULNOC) (registered trademark) R manufactured by New chemical industry (Dai-Nei-san Co., Ltd.) ]

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

Accelerator DM: di-2-benzothiazolyl disulfide [ Suxin (SUNSINE) MBTS and thiazole-based accelerator manufactured by Shandong county Chemical (Shandong Shanxin Chemical) ]

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 21mm and an inner diameter of 7mm, 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 7.5mm and coated with a conductive thermosetting adhesive (polyamide-based) on the outer peripheral surface thereof, and heated in an oven to 160 ℃.

Thus, the rubber composition is secondarily crosslinked and the thermosetting adhesive is subjected to a curing reaction, and after the cylindrical body and the metal shaft are electrically joined and mechanically fixed, both ends of the cylindrical body are shaped.

Next, the outer peripheral surface of the cylindrical body was longitudinally polished using a cylindrical grinder, followed by mirror polishing using a #2000 polishing film [ a mirror film (registered trademark) manufactured by triclinic chemistry (jet) ], as finish polishing, and the outer diameter was finished to be phi 20.00mm (tolerance 0.05).

Next, after the polished outer peripheral surface was wiped with alcohol, the distance from the UV light source to the outer peripheral surface was set to 50mm, and the resultant was set in a UV treatment apparatus.

Then, the developing roller was manufactured by irradiating ultraviolet rays while rotating at 30rpm around a shaft to form an oxide film and a roller body.

The proportion of the specific high-cis BR is 20 parts by mass out of 100 parts by mass of the total amount of the rubber.

< example 2 >

A rubber composition was prepared and a developing roller was produced in the same manner as in example 1 except that 55 parts by mass of GECO [ EPION 301 (low Vis type) manufactured by OSAKA dada (OSAKA SODA) (stock) mentioned above ], 5 parts by mass of CR [ SHOPRENE (SHOPRENE) WRT manufactured by showa and electrician (stock) mentioned above ], 5 parts by mass of NBR [ Nibo (NIPOL) DN401LL manufactured by nippon (stock) mentioned above ] and 35 parts by mass of special high cis BR [ Usppo (UBEPOL) BR150B manufactured by yuju xiong (stock) mentioned above ] were used as rubbers.

The proportion of the specific high-cis BR is 35 parts by mass out of 100 parts by mass of the total amount of the rubber.

< example 3 >

Except that the same amount of eucalyptus (UBEPOL) BR150L produced by yujuxing (stock) presented above was formulated [ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1% non-oil extended ] A rubber composition was prepared and a developing roller was produced in the same manner as in example 2, except that the specific high cis BR was changed to 1%.

< example 4 >

Except that the same amount of the above proposed Upjo (UBEPOL) VCR450[ cis-1, 4 bond content: 98%, trans-1, 4 bond content: 1%, 1,2 bond content: 1%, n-hexane-insoluble component: 3.8% ] A rubber composition was prepared and a developing roller was produced in the same manner as in example 2, except that the specific high cis BR was used.

< comparative example 1 >

Except that the same amount of a conventional BR having a cis-1, 4 bond content of 96% (Uuspelol (UBEPOL) BR130B manufactured by Youji province (stock Co., Ltd.): 96%, trans-1, 4 bond content: 2%, 1,2 bond content: 2% non-oil extended ] A rubber composition was prepared and a developing roller was produced in the same manner as in example 2, except that the specific high-cis BR was replaced.

< example 5 >

A rubber composition was prepared and a developing roller was produced in the same manner as in example 1 except that 45 parts by mass of GECO [ EPION 301 (low Vis type) manufactured by OSAKA dada (OSAKA SODA) (stock) mentioned above ], 5 parts by mass of CR [ SHOPRENE (SHOPRENE) WRT manufactured by showa and electrician (stock) mentioned above ], 5 parts by mass of NBR [ Nibo (NIPOL) DN401LL manufactured by japanese swingle (ZEON) (stock) mentioned above ] and 45 parts by mass of specific high cis BR [ Usppo (UBEPOL) VCR450 manufactured by yu xixing (stock) mentioned above ] were used as rubbers.

The proportion of the specific high-cis BR is 45 parts by mass out of 100 parts by mass of the total amount of the rubber.

< example 6 >

A rubber composition was prepared and a developing roller was produced in the same manner as in example 1 except that 40 parts by mass of GECO [ EPION 301 (low Vis type) manufactured by OSAKA dada (OSAKA SODA) (stock) mentioned above ], 5 parts by mass of CR [ SHOPRENE (SHOPRENE) WRT manufactured by showa and electrician (stock) mentioned above ], 5 parts by mass of NBR [ Nibo (NIPOL) DN401LL manufactured by japanese swingle (ZEON) (stock) mentioned above ] and 50 parts by mass of specific high cis BR [ Usppo (UBEPOL) VCR450 manufactured by yu xixing (stock) mentioned above ] were used as rubbers.

The proportion of the specific high-cis BR is 50 parts by mass out of 100 parts by mass of the total amount of the rubber.

< comparative example 2 >

A rubber composition was prepared and a developing roller was produced in the same manner as in example 1 except that 30 parts by mass of GECO [ EPION 301 (low Vis type) manufactured by OSAKA dada (OSAKA SODA) (stock) mentioned above ], 5 parts by mass of CR [ SHOPRENE (SHOPRENE) WRT manufactured by showa and electrician (stock) mentioned above ], 5 parts by mass of NBR [ Nibo (NIPOL) DN401LL manufactured by japanese swingle (ZEON) (stock) mentioned above ] and 60 parts by mass of specific high cis BR [ Usppo (UBEPOL) VCR450 manufactured by yu xixing (stock) mentioned above ] were used as rubbers.

The proportion of the specific high-cis BR is 60 parts by mass out of 100 parts by mass of the total amount of the rubber.

< practical machine test >

The developing rollers manufactured in the examples and comparative examples were incorporated into a new cartridge (a cartridge in which a toner container containing toner, a photoreceptor, and a developing roller in contact with the photoreceptor are integrated) for a commercially available laser printer, instead of a pure developing roller.

The laser printer uses a positively charged non-magnetic 1-component toner, and the recommended number of prints of the toner is about 20000.

(evaluation of toner leakage)

The ink cartridge is loaded into an initial laser printer, and images are continuously formed up to the recommended number of printed toner sheets (20000 sheets) in an environment of a temperature of 23 ± 1 ℃ and a relative humidity of 55 ± 1%.

Next, toner leakage was observed around the cartridge, and the presence or absence of toner leakage was evaluated according to the following criteria.

O: toner leakage was not observed at all.

And (delta): toner leakage was slightly observed, but not to the extent of affecting the formed image.

X: toner leakage was observed in a range that affects the formation of an image.

(evaluation of initial image)

The ink cartridge was loaded into a laser printer in an initial state, and a halftone image and a solid black image were formed in an environment with a temperature of 23. + -. 1 ℃ and a relative humidity of 55. + -. 1%.

Then, the formed two images were observed, and the initial image was evaluated according to the following criteria.

O: no image defects were observed at all.

And (delta): image defects were slightly observed, but not to the extent of affecting the formed image.

X: image defects were observed in a range that affects the formation of an image.

The results are shown in tables 3 and 4.

[ Table 3]

[ Table 4]

From the results of examples 1 to 6 and comparative example 1 in tables 3 and 4, it is understood that the following developing roller can be obtained by blending a specific high-cis BR in a ratio of 20 parts by mass or more to 100 parts by mass of the total amount of rubber in a system including epichlorohydrin rubber and CR: the roller has a simple structure in which the entire roller body is integrally formed of a crosslinked product of the same rubber composition, and abrasion of the end portion is suppressed to prevent leakage of toner and the like.

However, from the results of examples 1 to 6 and comparative example 2, it is found that in order to maintain the above-described effects and maintain the flexibility of the roller body and form an image with good image quality, the ratio of the specific high cis BR needs to be 50 parts by mass or less out of 100 parts by mass of the total amount of the rubber.

Further, from the results of examples 1 to 6, it is understood that the proportion of the specific high-cis BR is preferably 35 parts by mass or more, and preferably 45 parts by mass or less, out of 100 parts by mass of the total amount of the rubber, within the above range, in view of further improving these effects.

Claims

1. A developing roller comprises a roller body integrally formed of a crosslinked product of a rubber composition containing at least epichlorohydrin rubber, chloroprene rubber, and butadiene rubber having a cis-1, 4 bond content of 97% or more as rubbers, and the proportion of the butadiene rubber is 20 parts by mass or more and 50 parts by mass or less in 100 parts by mass of the total amount of the rubbers.

2. The developer roller of claim 1, wherein the rubber further comprises acrylonitrile butadiene rubber.

3. The developing roller according to claim 1 or 2, comprising an oxide film covering an outer circumferential surface of the roller body.