JP7340071B2 - elastic roller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elastic roller that satisfactorily suppresses the occurrence of filming and a decrease in print density.

2. Description of the Related Art A developing roller used in image forming apparatuses such as copiers, printers, and facsimiles that employ an electrophotographic method has a function of conveying a developer to an image carrier on which an electrostatic latent image is formed. The developer transportability of the developing roller affects the quality of the image forming apparatus, especially the print density. Therefore, it has been studied to improve the developer transportability of the developing roller by forming unevenness on the surface of the developing roller and adjusting the electrical properties of various materials constituting the developing roller.

Here, when the developing roller is used for a long period of time, developer may adhere to its surface (referred to as "filming"). Such filming is caused by, for example, deformation or destruction of the developer due to sliding stress of a blade or the like that presses against the elastic roller when charging or adhering the developer, and development due to frictional heat with the blade or the like. It is thought that this is caused by the melting of the agent or the like. Conventionally, in the manufacture of developing rollers, it has been desired to provide an elastic roller in which the occurrence of filming is suppressed as much as possible, thereby stabilizing durable printing performance.

For example, Patent Document 1 describes an elastic roller that has been studied for suppression of filming. and a toner carrying layer, wherein particles having an average particle diameter of 11 nm or more and 40 nm or less are dispersed on the surface of the toner carrying layer, and the rotational torque of the developing roller is 2.5 N or more and 3.5 N or less. An elastic roller is disclosed which is characterized by:

Further, in Patent Document 2, at least a shaft made of metal, an elastic layer supported on the outer periphery of the shaft, and a surface layer formed on the outer peripheral surface of the elastic layer, the surface layer is a fluoroethylene vinyl ether copolymer. Polyurethane composed of a reaction product of a coalescence and a cyanurate of isocyanate, and fine particles having a primary particle diameter of 5 to 30 nm, and the polyurethane has a peak intensity ratio of 5 between the NCO group and the hydroxyl group in the infrared absorption spectrum measured by the ATR method. .6 to 8.8.

JP 2016-177253 A JP 2014-215546 A

However, with the elastic rollers described in Patent Documents 1 and 2, even if the occurrence of filming is suppressed, the electrostatic capacity for carrying or supplying the developer tends to decrease, resulting in stable development. In some cases, the agent could not be charged, resulting in a decrease in print density.
SUMMARY OF THE INVENTION It is an object of the present invention to provide an elastic roller in which occurrence of filming and reduction in print density are well suppressed.

The inventors of the present invention have made intensive studies and found that an elastic roller comprising a shaft, an elastic layer provided on the outer peripheral surface of the shaft, and a surface layer provided outside the elastic layer, wherein the elastic layer , the dielectric constant of the surface layer, and the dielectric constant of the adhesive layer or the primer layer provided between the elastic layer and the surface layer, to solve the above problems, and completed the present invention. reached. Specifically, the present invention provides the following.

(1) An elastic roller comprising a shaft, an elastic layer provided on the outer peripheral surface of the shaft, and a surface layer provided outside the elastic layer, wherein the elastic roller comprises the elastic layer and the surface layer. and the elastic layer has a resistance value of 1×10 ⁴ Ω or more and 5×10 ⁶ Ω or less, and the adhesive layer has a dielectric constant of 1 or more and 10 or less at 100 Hz. , 1000 or more and 10000 or less at 0.01 Hz, and the dielectric constant of the surface layer is 1 or more and 10 or less at 100 Hz and 10 or more and 200 or less at 0.01 Hz.

(2) The elastic roller according to (1), wherein the adhesive layer contains an organic titanium compound and/or an organic zirconium compound.

(3) The surface layer is composed of silicone rubber particles and/or acrylic particles of 2 μm or more and 10 μm or less in a binder main agent obtained by mixing and reacting an isocyanurate-type isocyanate compound and/or an adduct-type isocyanate compound with both end-modified silicone oil. and a second isocyanate compound are added and cured to form the elastic roller according to (1) or (2).

(4) The surface layer is made by mixing a carbonate polyol and/or a fluoropolyol with both end-modified silicone oil, and further mixing and reacting an isocyanurate-type isocyanate compound and/or an adduct-type isocyanate compound. The elastic roller according to any one of (1) to (3), which is formed by adding and curing silicone rubber particles and/or acrylic particles of 2 μm or more and 10 μm or less and a second isocyanate compound.

In the elastic roller of the present invention, the dielectric constant of the surface layer is 1 or more and 10 or less at 100 Hz, and 10 or more and 200 or less at 0.01 Hz. By adjusting the relative permittivity of the surface layer at 100 Hz and 0.01 Hz to the above ranges, the occurrence of filming can be suppressed satisfactorily. Further, in the elastic roller of the present invention, an adhesive layer is provided between the elastic layer and the surface layer, and the dielectric constant of the adhesive layer is 1 or more and 10 or less at 100 Hz and 1000 or more and 100000 or less at 0.01 Hz. be. In order to satisfactorily suppress the occurrence of filming by adjusting the relative dielectric constant of the adhesive layer to the range, even if the relative dielectric constant of the surface layer is adjusted to be low as described above, it is possible to carry or supply the developer. It is possible to secure the electrostatic capacity for the charging, stably charge the developer, and suppress the decrease in print density. Furthermore, since the resistance value of the elastic layer is 1×10 ⁴ Ω or more and 5×10 ⁶ Ω or less, it is possible to stabilize the chargeability of the developer particularly in the initial stage. Therefore, according to the present invention, it is possible to provide an elastic roller that satisfactorily suppresses the occurrence of filming and a decrease in print density.

It is drawing which shows the elastic roller of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings.

<Elastic roller>
The elastic roller 1 of the present invention includes a shaft 2 , an elastic layer 3 provided on the outer surface of the shaft 2 , and a surface layer 4 provided outside the elastic layer 3 . The elastic roller 1 of the present invention is preferably used as a developing roller, but is not limited to such use.

[Shaft]
As the shaft 2, a shaft used for a conventionally known elastic roller, which has conductive properties, can be preferably used. The shaft 2 is preferably made of, for example, at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. In addition, such a shaft 2 is generally known by the name of "metal core".

The shaft 2 may contain insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft 2 may include, for example, a core made of insulating resin and a plated layer provided on the core. Such a shaft 2 can be obtained, for example, by plating a core made of an insulating resin to make it conductive.

The shaft 2 is preferably a metal core in order to obtain good conductive properties.

The shape of the shaft 2 is preferably, for example, rod-like or tubular. The cross-sectional shape of the shaft 2 may be, for example, circular, elliptical, or non-circular such as polygonal. The outer peripheral surface of the shaft body 2 may be subjected to a cleaning treatment, a degreasing treatment, a primer treatment, or the like.

The axial length of the shaft 2 is not particularly limited, and may be appropriately adjusted according to the form of the installed image forming apparatus. Also, the diameter of the shaft 2 (the diameter of the circumscribed circle) is not particularly limited, and may be appropriately adjusted according to the form of the installed image forming apparatus.

[Elastic layer]
In the elastic roller 1 of the present invention, the resistance value of the elastic layer 3 is 1×10 ¹ Ω or more and 1×10 ⁷ Ω or less. By adjusting the resistance value of the elastic layer 3 within the above range, it is possible to stabilize the chargeability of the developer particularly in the initial stage (for example, about 1 to 500 sheets) and suppress the decrease in print density. The resistance value of the elastic layer 3 is preferably 1×10 ³ Ω or more and 1×10 ⁷ Ω or less, more preferably 1×10 ⁴ Ω or more and 5×10 ⁶ Ω or less.

The elastic layer 3 is made of a rubber material containing silicone rubber. By including silicone rubber in the elastic layer 3, the effects of being able to reduce the compression set and being excellent in flexibility in a low-temperature environment can be obtained.

Examples of silicone rubbers include crosslinked organopolysiloxanes such as dimethylpolysiloxane and diphenylpolysiloxane. Also, the silicone rubber may be a modified product of these.

The elastic layer 3 preferably contains mainly silicone rubber. Specifically, the content of the silicone rubber in the elastic layer 3 is preferably 30% by mass or more, more preferably 40% by mass or more, more preferably 60% by mass, based on the total mass of the elastic layer 3. It is more preferable that it is above.

The elastic layer 3 may contain components other than the rubber material. For example, the elastic layer 3 may further contain a conductivity imparting agent. The conductivity imparting agent is not particularly limited as long as it is a component for imparting conductivity to the elastic layer 3 . Examples of the conductivity-imparting agent include conductive powder containing conductive carbon, carbons for rubber, metals, conductive polymers, and the like. Carbon black is preferably used as the conductive powder, and examples of carbon black include furnace black such as Ketjenblack (registered trademark), acetylene black, channel black, and thermal black.

In the elastic roller 1, the elastic layer 3 is formed so that the outer peripheral surface of the shaft 2 is exposed at both ends of the shaft 2 in the axial direction. That is, there is a region on the outer peripheral surface of the shaft 2 where the elastic layer 3 is not provided. However, the aspect of the elastic layer 3 in the present invention is not limited to such an aspect, and the elastic layer 3 may be provided so as to cover the entire outer peripheral surface of the shaft 2 .

The elastic layer 3 may be a solid layer and preferably does not have a hollow inside. As used herein, the term “solid” means that the layer does not have hollows of 0.1 mm ² /piece or more inside.

The JIS A hardness of the elastic layer 3 is preferably 20 or more and 55 or less. Since the JIS A hardness (JIS K 6301) of the elastic layer 3 is within the above range, the contact area (nip width) between the elastic roller 1 and the contacted member (for example, an image bearing member such as a photoreceptor) is large. Therefore, performances such as transfer efficiency, charging efficiency, and development efficiency tend to be further improved. In addition, the possibility of giving mechanical damage to the contacted body is reduced.

The thickness of the elastic layer 3 is preferably 0.5 mm or more and 10 mm or less from the viewpoint of ensuring a uniform nip width with the contacted body in the contact state with the contacted body. , 1 mm or more and 5 mm or less. In this specification, the term "thickness" means the thickness of the elastic roller 1 in the direction perpendicular to its axial direction. The outer diameter of the elastic layer 3 is not particularly limited. The outer diameter may be, for example, 5 mm or more and 20 mm or less. In this specification, the term “outer diameter” means the outer diameter of the cross section of the elastic roller 1 perpendicular to the axial direction. The thickness and outer diameter of the elastic layer 3 can be determined by adjusting the amount of the rubber composition used when forming the elastic layer 3, polishing or grinding the outer peripheral surface of the elastic layer 3 after forming the elastic layer 3, or the like. can be adjusted by

The outer peripheral surface of the elastic layer 3 may be subjected to surface treatment such as primer treatment, corona treatment, plasma treatment, excimer treatment, UV treatment, itro treatment, and flame treatment.

The elastic layer 3 may be a cured rubber composition described below.

(rubber composition)
The above rubber composition preferably contains a rubber component that forms a silicone rubber by crosslinking. Examples of such a rubber component include silicone raw rubber such as organopolysiloxane.

Examples of organopolysiloxane include organopolysiloxane represented by the following average composition formula.
RnSiO _(4-n)/2
[R represents an optionally substituted monovalent hydrocarbon group. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less. Plural Rs may be the same or different. n represents a number of 1.95 or more and 2.05 or less. ]

Examples of R in the above formula include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, cycloalkyl groups such as cyclohexyl group, vinyl group, allyl group, butenyl group and hexenyl group. alkenyl groups such as groups, phenyl groups, aryl groups such as tolyl groups, aralkyl groups such as β-phenylpropyl groups, and hydrogens bonded to carbon atoms of the above groups such as chloromethyl groups, trifluoropropyl groups, cyanoethyl groups, etc. Examples include organic groups in which some or all of the atoms are substituted with halogen atoms, cyano groups, or the like.

The organopolysiloxane is preferably an organopolysiloxane containing at least two silicon-bonded alkenyl groups per molecule. For example, in the above formula, it is preferred that at least two R have the above alkenyl group. Organopolysiloxane more preferably has a vinyl group.

Specific examples of organopolysiloxane include dimethylpolysiloxane and diphenylpolysiloxane. The organopolysiloxane preferably has a molecular chain end blocked with a trimethylsilyl group, a dimethylvinylsilyl group, a dimethylhydroxysilyl group, a trivinylsilyl group, or the like.

The rubber composition may contain various additives. Such additives include, for example, auxiliary agents such as conductivity imparting agents, chain extenders and cross-linking agents, catalysts such as addition reaction catalysts, reaction control agents, dispersants, anti-aging agents, antioxidants, fillers, materials, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardant improvers, acid acceptors, heat conductivity improvers, release agents, solvents, etc. can.

The rubber composition may be a liquid rubber composition or a millable rubber composition.

[surface]
The surface layer 4 is provided on the outermost surface of the elastic roller 1 . In the present invention, the dielectric constant of the surface layer 4 is 1 or more and 10 or less at 100 Hz, and 10 or more and 100 or less at 0.01 Hz. By adjusting the relative permittivity of the surface layer 4 at 100 Hz and 0.01 Hz to the above range, the mirror image force and van der Waals force acting as the bonding force between the external additive silica in the developer and the surface of the elastic roller are reduced. can be obtained, and the occurrence of filming can be suppressed satisfactorily. The dielectric constant of the surface layer 4 is preferably 1 or more and 5 or less at 100 Hz, and preferably 7 or more and 120 or less at 0.01 Hz.

In order to prevent filming from occurring in the elastic roller 1, at least the properties of the surface layer 4 must be adjusted. In the present invention, the surface layer 4 is obtained by coating and curing a mixture of the following components (A) to (D).
(A) a binder main component obtained by polymerizing a composition comprising a silicone oil modified at both ends and an isocyanate compound;
(B) a second isocyanate compound,
(C) silicone rubber particles and/or acrylic particles having a particle size of 0.2 μm or more and 10 μm or less;
(D) Dilution solvent.

The above mixture is in a liquid state before being cured by heating.

((A) binder main agent)
The binder main component is obtained by polymerizing a composition comprising both terminal-modified silicone oil and an isocyanate compound. If necessary, this composition may further contain a fluororesin such as a one-end diol-modified silicone oil, a polyol, and a tetrafluoroethylene copolymer.

(both ends modified silicone oil)
The both-terminal-modified silicone oil is one type of so-called reactive silicone oil, and has the property of polymerizing with an isocyanate compound. Therefore, both ends of the silicone chain are preferably modified with an amino group (primary or secondary amino group), a mercapto group, or a hydroxyl group. These both terminal-modified silicone oils are commercially available as both terminal amino-modified silicone oils, both terminal mercapto-modified silicone oils, both terminal carboxyl-modified silicone oils, both terminal phenol-modified silicone oils, and both terminal carbinol-modified silicone oils.

Here, as a preferable both-ends-modified silicone oil used in the present invention, there can be mentioned both-ends-modified silicone oil represented by the following general formula (1).

In general formula (1), R represents —C ₃ H ₆ OC ₂ H ₄ OH or —C ₃ H ₆ OCH ₂ —C(CH ₂ OH) ₂ C ₂ H ₅ , and n is 20 or less. represents an integer.

Among both terminal-modified silicone oils represented by the general formula (1), it is particularly preferable to use a silicone oil in which R at both terminals is —C ₃ H ₆ OC ₂ H ₄ OH and n is about 10. . As for such silicone oil, commercially available products can be obtained as appropriate.

In general formula (1), the functional group bonded to the silicon atom is a methyl group, but the silicone oil may be modified silicone oil at both ends in which the methyl group is substituted with a hydrogen atom.

By containing the modified silicone oil at both ends in the mixture for forming the surface layer 4, it is possible to impart appropriate elasticity to the surface layer 4, adjust the electrical properties of the surface layer 4, and adjust the dielectric properties of the surface layer 4. rate can be reduced, and the occurrence of filming can be effectively suppressed.

(Single-end diol-modified silicone oil)
The single-end diol-modified silicone oil is a reactive silicone oil like the both-end-modified silicone oil, but has two hydroxyl groups bonded to one end of the silicone chain. Generally, when a silicone oil modified at both ends and an isocyanate compound are polymerized, linear polyurethane is produced. can improve the nano-level fine roughness.

Examples of the single-end diol-modified silicone oil include a single-end-modified silicone oil represented by the following general formula (2).

In general formula (2), R' represents _{-C3H6OCH2 -} C( _CH2OH ) _2C2H5 , and n represents an integer _{of 20} or _less .

Among the single-ended diol-modified silicone oils represented by the general formula (2), it is particularly preferable to use silicone oils in which n is about 10. In general formula (2), the functional group bonded to the silicon atom is a methyl group, but silicone oil in which the methyl group is substituted with a hydrogen atom may also be used.

In the present invention, the one-end diol-modified silicone oil used for preparing the binder main component is preferably 1 part by mass or more and 5 parts by mass or less, and 2 parts by mass, with respect to 100 parts by mass of both-end-modified silicone oil. It is more preferable that the content is 4 parts by mass or less. By adjusting the surface roughness of the surface layer 4 by adjusting the amount of the one-end diol-modified silicone oil to the both-end-modified silicone oil to be within the above range, the film can be formed while maintaining good development performance. ming can be effectively prevented.

(isocyanate compound)
In the present invention, the isocyanate compound used for preparing the main binder component is not particularly limited as long as it has reactivity with the reactive groups introduced into the silicone oil. For example, diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI) and other diisocyanates, and modifications of these isocyanates such as adduct type, burette type, isocyanurate type and allophanate type. Among these isocyanate compounds, isocyanurate-type isocyanate compounds and adduct-type isocyanate compounds are preferred, and these may be used alone or in combination. The longer the molecular chain of the isocyanate compound is, the more flexible the polyurethane can be produced.

In the present invention, the isocyanate compound used for preparing the binder main component is preferably 7.78 parts by mass or more and 23.30 parts by mass or less with respect to 100 parts by mass of both terminal-modified silicone oil, and 11.67 parts by mass. More preferably, the amount is not less than 19.45 parts by mass. By setting the amount of the isocyanate compound used relative to the silicone oil modified at both ends within the above range, the viscosity of the mixture for forming the surface layer 4 can be optimized, and workability can be improved.

(Carbonate polyol, hydrogenated butadiene polyol, fluorine polyol)
A carbonate polyol, a fluoropolyol, and a hydrogenated butadiene polyol react with the isocyanate compound described above and the second isocyanate compound described later to form a polyurethane. In the present invention, these polyols may be used alone, or a plurality of polyols may be used in combination. As polyols to be used, carbonate polyols and fluorine polyols are preferably used alone or in combination.

The carbonate polyol and/or the fluoropolyol are preferably 5 parts by mass or more and 40 parts by mass or less, more preferably 15 parts by mass or more and 25 parts by mass or less with respect to 100 parts by mass of the silicone oil modified at both ends. Commercially available products can be used as these polyols.

((B) second isocyanate compound)
As the isocyanate compound, various isocyanate compounds (eg, aromatic isocyanate compounds, aliphatic isocyanate compounds, alicyclic isocyanate compounds) commonly used in polyurethane preparation can be used. Examples of aromatic isocyanate compounds include 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), 4,4′-diphenylmethane diisocyanate (4,4 '-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, polymethylene polyphenylene polyisocyanate, tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), 3,3'-dimethylbiphenyl-4,4'-diisocyanate and the like can be mentioned. Examples of aliphatic isocyanate compounds include hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornene diisocyanatomethyl (NBDI), xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate. (TMXDI) and the like. Furthermore, alicyclic polyisocyanates include, for example, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), 4,4′-dicyclohexylmethane. Diisocyanate and the like can be mentioned.

In the present invention, the amount of the second isocyanate compound used in the mixed liquid used to form the surface layer 4 is such that the reaction rate of the second isocyanate compound is 80% or more and 126% or less, preferably 95% or more and 112% or less. is preferably used so that

((C) silicone rubber particles, acrylic particles)
The mixed liquid for forming the surface layer 4 contains silicone rubber particles and/or acrylic particles. The particle size of the silicone rubber particles and acrylic particles is preferably 0.2 μm or more and 10 μm or less, more preferably 0.8 μm or more and 5 μm or less. By setting the particle diameters of the silicone rubber particles and the acrylic particles within the above range, the surface roughness of the elastic roller 1 is appropriately maintained, and the developer transportability is maintained well, while the resolution is high. It is possible to maintain the standard and prevent the deterioration of the image quality. The particle sizes of the silicone rubber particles and the acrylic particles can be measured by observing the cross section with a microscope after cutting the elastic roller 1 .

The silicone rubber particles and acrylic particles used in the present invention preferably have heat resistance such that they do not deform or melt even at temperatures of 100°C or higher, and more preferably have heat resistance from 130°C to 180°C. As a result, deformation of these silicone rubber particles and acrylic particles can be prevented even at the cross-linking temperature of the surface layer 4 . The heat resistance of silicone rubber particles and acrylic particles can be evaluated by confirming that the silicone rubber particles and acrylic particles do not melt and flow out even when pressure and heat are applied in a melt flow indexer.

The hardness of the silicone rubber particles and acrylic particles is preferably 20 degrees or more and 80 degrees or less, more preferably 50 degrees or more and 75 degrees or less, as measured by durometer A (instantaneous) (JIS K 6253: 1997). . When the hardness of the silicone rubber particles and the acrylic particles is within the above range, it is possible to effectively prevent an increase in the coefficient of friction of the surface layer 4 and the occurrence of sticking due to destruction or deformation of the silicone rubber particles and the acrylic particles. At the same time, it is possible to prevent the surface layer 4 from cracking or splitting due to excessive hardness of the surface layer 4, and to prevent excessive stress from being applied to the toner.

The silicone rubber particles and acrylic particles may be present (embedded) in the surface layer 4 or part of them may protrude from the surface of the surface layer 4 . Moreover, it may be unevenly distributed in the surface layer 4 or unevenly distributed on the surface side of the surface layer 4 .

Among silicone rubber particles and acrylic particles, silicone rubber particles preferably have a structure obtained by cross-linking dimethylpolysiloxane, organopolysiloxane, or polyorganosilsesoxane. Commercially available acrylic particles can be used as acrylic particles. can be done.

Regarding the silicone rubber particles, the organic groups include alkyl groups such as methyl group, ethyl group, propyl group and butyl group; aryl groups such as phenyl group and tolyl group; alkenyl groups such as vinyl group and allyl group; aralkyl groups such as phenylethyl group and β-phenylpropyl group; monovalent halogenated hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group; epoxy group, amino group, mercapto group, acryloxy group, Organopolysiloxane or organopolysilsesquioxane having a group selected from one or more monovalent organic groups having 1 to 20 carbon atoms selected from reactive group-containing organic groups such as methacryloxy groups These particles prepared from organopolysiloxane or organopolysilsesquioxane may be surface-treated with organoalkoxysilane. Examples of such silicone rubber particles include "KMP-597" manufactured by Shin-Etsu Chemical Co., Ltd., and "EP-5500", "EP-2600" and "EP-2601" manufactured by Dow Corning Toray Co., Ltd. , “E-2720”, “DY 33-430M”, “EP-2720”, “EP-9215 Cosmetic Powder”, “9701 Cosmetic Powder” and the like can be used.

The amount of silicone rubber particles and/or acrylic particles used is preferably 15 parts by mass or more and 40 parts by mass or less, more preferably 20 parts by mass or more and 35 parts by mass or less, relative to 100 parts by mass of the main binder component. . By setting the amount of the silicone rubber particles and/or the acrylic particles to be within the above range, the surface roughness of the elastic roller 1 can be properly maintained, and the developer transportability can be maintained well. , the resolution can be maintained at a high level and the deterioration of the image quality can be prevented.

((D) dilution solvent)
As the diluent solvent, an aqueous solvent and an organic solvent can be used, and a low boiling point solvent and a high boiling point solvent can be used in combination according to the required drying rate.

In the present invention, in the mixture for forming the surface layer 4, the solid content concentration is preferably within the range of 10% by mass or more and 50% by mass or less, and is within the range of 20% by mass or more and 40% by mass or less. is more preferred. If the solid content concentration is low, the liquid tends to sag during coating and takes a long time to dry.

In the present invention, as the diluent solvent, it is preferable to use a diluent solvent that swells the above-mentioned silicone rubber particles or acrylic particles. As a result, the silicone rubber particles and acrylic particles swell in the mixed liquid, and the surface layer 4 can be made free of repelling and dents, and sedimentation of the silicone rubber particles and acrylic particles in the mixed liquid is suppressed. be able to.

As such a diluting solvent, organic solvents such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), tetrahydrofuran (THF), acetone, ethyl acetate, butyl acetate, toluene, xylene, heptane, cyclohexanone, and isophorone can be used. preferable.

[Adhesion layer]
The elastic roller 1 of the present invention includes adhesive layers between the shaft 2 and the elastic layer 3 and between the elastic layer 3 and the surface layer 4 . Here, especially with respect to the adhesive layer provided between the elastic layer 3 and the surface layer 4, the electrical characteristics of the elastic roller 1 can be adjusted by adjusting the electrical characteristics of the adhesive layer. The developing performance of the elastic roller 1 as a developing roller can be adjusted satisfactorily.
In the elastic roller 1 of the present invention, the dielectric constant of the adhesive layer is 1 or more and 10 or less at 100 Hz and 1000 or more and 10000 or less at 0.01 Hz. By adjusting the dielectric constant of the adhesive layer to the range, even if the dielectric constant of the surface layer is adjusted to be low in order to satisfactorily suppress the occurrence of filming, the electrostatic charge for carrying or supplying the developer is reduced. It is possible to secure the capacity and stably charge the developer. Therefore, it is possible to suppress a decrease in print density during printing. The dielectric constant of the adhesive layer is preferably 4.0 or more and 10.0 or less at 100 Hz, and preferably 2000 or more and 5000 or less at 0.01 Hz.

The adhesive layer preferably contains an organic titanium compound and/or an organic zirconium compound, and more preferably contains these organic metal compounds and a silane coupling agent. By using the organic titanium compound and the organic zirconium compound together with the silane coupling agent, the dielectric constant of the elastic layer 3 is increased, the development performance is maintained well, and the adhesion between the elastic layer 3 and the surface layer 4 is achieved. can improve the properties. Examples of organic titanium compounds include titanium compounds containing alkoxy groups and titanium chelate compounds. Examples of organic zirconium compounds include zirconium compounds and zirconium chelate compounds containing alkoxy groups. As these organotitanium compounds and organozirconium compounds, commercially available ones can be appropriately used.

Hereinafter, the present invention will be described in detail with reference to examples. It should be noted that the present invention is by no means limited to the examples shown below.

<Preparation of binder main agent>
The following materials were mixed to prepare a composition for preparing a binder base, and this was maintained at 100° C. to 120° C. for 4 to 6 hours to prepare a binder base. Table 1 shows detailed formulations for preparing the composition for preparing the main binder component.

[(A) Composition for preparing binder main component]
(A1) Both terminal hydroxyl group modified dimethyl silicone oil (A2) Single terminal diol modified silicone oil (A3) Carbonate diol (A4) Tetrafluoroethylene copolymer polyol (A5) Polyester polyol (A6) Isocyanate compound (adduct type isocyanate )
(A7) isocyanate compound (isocyanurate-type isocyanate)

<Preparation of mixed solution for forming surface layer>
A mixture solution for forming a surface layer was prepared by mixing a binder main component and each material shown below. Table 2 shows detailed formulations for preparing the mixture.

[(B) Second isocyanate compound]
(B1) isocyanurate-type isocyanate (B2) adduct-type isocyanate

[(C) Silicone rubber particles, acrylic particles]
(C1) Silicone rubber beads (average particle size 2 μm)
(C2) Highly restorable acrylic fine particles (average particle diameter 3 μm)
(C3) Highly restorable acrylic fine particles (average particle diameter 10 μm)

[(D) dilution solvent]
(D1) butyl acetate

<Adhesive layer>
(E1) organosilane coupling agent (E2) organotitanium compound (titanium oligomer)
(E3) Organic zirconium compound (zirconium tributoxy monoacetylacetonate)

<Examples and Comparative Examples; Production of Developing Rollers>
A shaft (7.5 mm in diameter, 274.1 mm in length) made of free-cutting steel SUM23 was coated with a silicone-based primer on its surface and then dried in a gear oven at 150°C. By this operation, the outer peripheral surface of the shaft was treated with a primer.

An elastic body made of a rubber material was formed on the outer peripheral surface of the shaft by extrusion molding using a rubber composition made of silicone rubber. In the extrusion molding, the rubber composition formed from the silicone rubber was heated at 360°C for 5 minutes using an infrared heating furnace (IR furnace), and further heated at 200°C for 4 hours using a gear oven. Hardened. As a result, an elastic layer made of the cured rubber composition was formed on the outer peripheral surface of the shaft that had been subjected to the primer treatment. The elastic layer was a solid layer and the thickness of the elastic layer was 4.25 mm. Also, the resistance value of the elastic layer was measured using R8340 ULTRA HIGH RESISTANCE METER (manufactured by ADVANTEST Co., Ltd.) and found to be 1.00×10 ⁵ Ω.

Next, the outer peripheral surface of the elastic layer was UV-treated. After that, on the UV-treated elastic layer, an adhesive primer layer shown in Table 2 was applied according to each category of Examples and Comparative Examples, and then a mixed solution shown in Table 2 was applied by a spray method. A surface layer was formed on the elastic layer by heating the applied mixture at 150° C. to 160° C. for 30 minutes. The thickness of the surface layer was 7 μm.

<Evaluation>
(Measurement of print density and amount of filming)
The print density and the amount of filming were measured in the following manner for each developing roller manufactured. The image forming apparatus used was model number: HL-L2360DN (manufactured by Brother Industries, Ltd.). As the developing rollers of this image forming apparatus, each of the manufactured developing rollers was mounted in the developing device. Next, a solid image was formed under conditions of a temperature of 23° C. and a humidity of 55%, and the print evaluation was confirmed. The filming condition after printing 4000 sheets and the image quality after printing 4000 sheets (density step ratio between initial print formation portion and final print formation portion of solid printing) were evaluated. An X-Rite 500 spectrodensitometer manufactured by X-Rite was used for density measurement.

The print density was evaluated according to the following evaluation criteria. In this test, if the print density is evaluated as A, it is acceptable.
A: When the density difference ratio is 96 to 100% and the printed dots are clear B: When the density difference ratio is 92 to 95% and there are other problems (printed dots are rough) C : When the density step rate is 91% or less and there are other problems

Toner adhesion (filming) was evaluated by the amount of developer adhesion. Specifically, the mass transferred to the filming weight measuring jig was measured after sucking the developer adhering to the surface of the developing roller after printing 4000 sheets. The evaluation of filming was based on the following criteria based on the mass of the transferred developer. In this test, an evaluation of A or B for the amount of filming is acceptable.
A: 0 mg or more and 0.003 mg or less B: More than 0.003 mg and 0.006 mg or less C: More than 0.006 mg

(Measurement of dielectric constant)
The surface layer and adhesive layer of the developed developing roller were measured for relative permittivity at 0.01 Hz and 100 Hz using an LCR meter (manufactured by NF Circuit Design Block Co., Ltd.).

Table 2 shows the evaluation results.

REFERENCE SIGNS LIST 1 elastic roller 2 shaft 3 elastic layer 4 surface layer

Claims (6)

An elastic roller comprising a shaft, an elastic layer provided on the outer peripheral surface of the shaft, and a surface layer provided outside the elastic layer,
The dielectric constant of the surface layer is 1 or more and 10 or less at 100 Hz, and 10 or more and 200 or less at 0.01 Hz ,
An elastic roller comprising an adhesive layer between the elastic layer and the surface layer, wherein the adhesive layer has a dielectric constant of 1 or more and 10 or less at 100 Hz and 1000 or more and 10000 or less at 0.01 Hz. 2. The elastic roller according to claim 1, wherein the elastic layer has a resistance value of 1*10 ^<3 > [Omega] or more and 1*10 ^<7 > [Omega] or less. 2. The elastic roller according to claim 1, wherein the elastic layer has a JIS A hardness of 20 or more and 55 or less. 2. The elastic roller according to claim 1 , wherein the adhesive layer contains an organic titanium compound and/or an organic zirconium compound. The surface layer
A binder main agent obtained by mixing and reacting an isocyanurate-type isocyanate compound and/or an adduct-type isocyanate compound with both end-modified silicone oil,
2. The elastic roller according to claim 1, which is formed by adding and curing silicone rubber particles and/or acrylic particles having a size of 2 μm or more and 10 μm or less and a second isocyanate compound. The surface layer
Both end-modified silicone oil is mixed with a carbonate polyol and/or a fluoropolyol, and further mixed with an isocyanurate-type isocyanate compound and/or an adduct-type isocyanate compound and reacted to form a binder main component,
2. The elastic roller according to claim 1, which is formed by adding and curing silicone rubber particles and/or acrylic particles having a size of 2 μm or more and 10 μm or less and a second isocyanate compound.

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