JP2016188947A - Developing roller, developing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing roller that has excellent developer conveyability and durability and suppresses toner filming, and a developing device and an image forming apparatus including the developing roller.SOLUTION: There is provided a developing roller comprising a shaft body, rubber elastic layer, and coating layer, where the coating layer contains fine particles having an average particle diameter of 5 to 15 μm and has, its surface, irregular convex parts formed of the fine particles; the number of convex parts present in an area of 13125 μmon the surface is 100 or less; the coating layer has a ten-point average surface roughness Rz of 5.5 μm or less. Also provided are a developing device and an image forming apparatus including the developing roller.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing roller, a developing device, and an image forming apparatus.

  A developing roller used in an image forming apparatus (also referred to as an electrophotographic apparatus) such as a copying machine, a printer, or a facsimile employing an electrophotographic system has a function of conveying a developer to an image carrier on which an electrostatic latent image is formed ( Also called developer transportability). The developer transportability of the developing roller affects the quality of the image forming apparatus, particularly the print density. Accordingly, it has been studied to form irregularities on the surface of the developing roller, thereby improving the developer transportability of the developing roller.

For example, Patent Document 1 and Patent Document 2 describe a developing roller in which the surface roughness of the developing roller is adjusted by providing a surface layer in which resin particles are dispersed on the outermost surface of the developing roller.
In addition to these, a developing roller adjusted to a predetermined surface roughness by polishing the surface with a grindstone or the like, or a molding die adjusted to a predetermined roughness by blasting the inner surface of the molding die A developing roller or the like that is adjusted to a predetermined surface roughness by using an elastic layer and molding the elastic layer is also known.

JP 2009-265157 A JP 2002-304053 A

However, a developing roller having a surface layer in which resin particles are dispersed, such as the developing rollers described in Patent Document 1 and Patent Document 2, increases the contact area of the developing blade when mounted on an image forming apparatus. In some cases, filming (developing of the developer) is likely to occur.
In addition, the developing roller whose surface roughness has been adjusted by polishing is expensive and not so fine asperities are formed, so that toner filming is likely to occur, which tends to reduce durability. It was. Furthermore, the development roller molded by the blasted molding die has fine irregularities, so the amount of transport is small and the durability tends to be reduced, so that toner filming is likely to occur. was there.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing roller that is excellent in developer transportability and has excellent durability by suppressing toner filming, as well as a developing device and an image forming apparatus provided with the developing roller.

The object of the present invention has been achieved by the following means.
(1) A developing roller comprising a shaft, a rubber elastic layer formed on the outer periphery of the shaft, and a coating layer formed on the outer periphery of the rubber elastic layer,
The coating layer contains fine particles having an average particle diameter of 5 to 15 μm,
The surface of the coating layer has irregular protrusions formed of the fine particles, and the number of protrusions present in the 13125 μm ² region of the surface is 100 or less,
A developing roller having a ten-point average roughness Rz of the coating layer of 5.5 μm or less.
(2) to the total area _{S A} of the coating layer, the surface area ratio of the surface area _{S T} of the convex portion _(S T / _{S A)} is, according to a range of 0.05 to 0.2 (1) Development roller.
(3) The developing roller according to (1) or (2), wherein the coating layer has a surface layer on a surface thereof.
(4) The developing roller according to (3), wherein the surface layer contains at least one of Si element and fluorine element.
(5) A developing device including the developing roller according to any one of (1) to (4) above.
(6) An image forming apparatus comprising the developing roller according to any one of (1) to (4).

According to the present invention, it is possible to provide a developing roller excellent in developer transportability, suppressed in occurrence of toner filming and excellent in durability, and a developing device and an image forming apparatus including the developing roller.
The developing roller and the developing device of the present invention can contribute to the image forming apparatus forming a high density and high quality image over a long period of time. Further, the image forming apparatus of the present invention can form a high-density and high-quality image over a long period of time.

FIG. 1 is a schematic front view showing an example of the developing roller of the present invention. FIG. 2 is a schematic view showing an example of the developing device of the present invention and the image forming apparatus of the present invention.

The developing roller of the present invention will be described with a preferable example.
As shown in FIG. 1, the developing roller as a preferred example of the developing roller of the present invention includes a rod-like or tubular shaft body 2 and a tubular rubber elastic layer (not shown in FIG. 1) formed on the outer periphery of the shaft body. And a coating layer 4 formed on the outer periphery of the rubber elastic layer.

The shaft body 2 is the same as the shaft body in a conventionally known developing roller.
The shaft body 2 is a so-called “core metal” made of, for example, iron, aluminum, stainless steel, brass, or the like, and has good conductive characteristics. The shaft body 2 may be a shaft body made conductive by plating an insulating core body such as a thermoplastic resin or a thermosetting resin. The shaft body 2 is preferably made of metal and highly conductive.

The rubber elastic layer is formed on the outer periphery of the shaft body with SBR, NBR, epichlorohydrin rubber, EPDM, CR, BR, IR, acrylic rubber, silicone rubber and a composite thereof, and a modified product thereof. It is preferably formed of silicone rubber having a large molding shrinkage rate. The silicone rubber is not particularly limited, but is preferably a cured product of a silicone rubber composition described later.
The rubber elastic layer may be a foam layer made of foam rubber, but is preferably a solid layer in terms of excellent thickness accuracy. In the present invention, “solid” includes not only the case where there is no hollow part in the interior but also the case where there are, for example, 0.1 / mm ² or less hollow parts.

  The rubber elastic layer preferably has a JIS A hardness of 20 to 55. When the rubber elastic layer has a JIS A hardness (JIS K6301) of 20 to 55, the contact area (also referred to as nip width) between the developing roller and the contacted body increases, and transfer efficiency, charging efficiency, or development Efficiency is improved. In addition, the possibility of mechanical damage to the contacted body such as the photoreceptor is reduced.

  The thickness of the rubber elastic layer is preferably from 0.5 to 10 mm, and preferably from 1 to 5 mm, from the viewpoint that a uniform nip width with the contacted body can be secured in the contact state with the contacted body. Is particularly preferred. Although it does not specifically limit as an outer diameter of a rubber elastic layer, For example, it can be set as 5-20 mm.

  The coating layer 4 is formed on the outer periphery of the rubber elastic layer with a thermoplastic resin or a thermosetting resin. Especially, it is preferable to form with the urethane resin which is excellent in abrasion resistance, especially the polyester urethane resin. The urethane resin and the polyester urethane resin will be described later.

The coating layer 4 contains fine particles. These fine particles are preferably formed of a thermoplastic resin or a thermosetting resin, such as urethane resin, urea resin, cross-linked acrylic resin, cross-linked polystyrene, acrylic styrene copolymer, cross-linked olefin resin, or polyamide resin. The formed fine particles are more preferable.
The average particle diameter of the fine particles is 5 to 15 μm. When the average particle size is less than 5 μm, the surface roughness (ten-point average roughness Rz) of the developing roller 1 is reduced, and the developer transportability may be lowered. On the other hand, when the thickness exceeds 15 μm, the image quality of the formed image may deteriorate due to a decrease in resolution. The average particle diameter of the fine particles is preferably 5 to 14 μm, and more preferably 6 to 12 μm, from the viewpoint that both excellent developer transportability and high resolution can be achieved at a high level. The particle size of the fine particles can be measured by measuring the cross section with a microscope after cutting the developing roller 1.

  The fine particles preferably have heat resistance that does not deform or melt at 100 ° C. or higher, and more preferably has heat resistance at 130 to 180 ° C. Thereby, it can endure even the bridge | crosslinking temperature of the coating layer 4 without deform | transforming. Heat resistance is achieved by using a device that puts fine particles in a facility called a melt flow indexer and gives pressure and heat to produce fluidity, and even if given heat is given, the fine particles do not melt out of this device and flow out. I can confirm.

The fine particles may be present (buried) in the coating layer 4, and part of the fine particles may be present on the coating layer 4. Moreover, it may disperse | distribute unevenly in the coating layer 4, for example, may be unevenly distributed in the surface side.
Further, the shape of the fine particles is not particularly limited. For example, it may be granular, columnar, rod-shaped, indeterminate, or disk-shaped (flat).

  Since the coating layer 4 contains fine particles, the convex portions 4 a resulting from the fine particles are irregularly formed on the coating layer 4. For example, the coating layer 4 has the convex part 4a which protrudes or protrudes in a granular form with the microparticles | fine-particles which exist inside. The convex portion 4 a is formed by fine particles covered with the coating layer 4. Here, “irregular” means that the convex portions 4a are not in an arrayed state that is repeatedly arranged in a predetermined manner (arrangement manner and interval). For example, a state where particles are partially adhered to each other, or the arrangement pitch is random, or dispersed or scattered is exemplified.

The convex part 4a should just be formed in the coating layer 4, and the number is not specifically limited. In this invention, it has many convex parts 4a, and has the number of grades which satisfy the following convex part numbers.
About the number of the convex parts 4a which the coating layer 4 has (referred to as the number of convex parts), the number of convex parts existing in the region of 13125 μm ² (140 μm × 93.75 μm) in the surface of the coating layer 4 is 100 or less. If the number of protrusions exceeds 100, toner filming is likely to occur near the protrusions 4a on the surface, and the amount of developer (referred to as filming amount) that adheres to the coating layer 4 due to toner filming increases. The number of convex portions is preferably 90 or less, and more preferably 80 or less, in that the occurrence of toner filming can be suppressed for a long time and the amount of filming can be reduced. The lower limit value of the number of convex portions is not particularly limited as long as the convex portions 4a exist, but for example, it is preferably 1 or more, more preferably 2 or more, and further preferably 3 or more.

In the present invention, the number of convex portions is measured as follows.
That is, on the surface of the coating layer 4, a region where fine particles are present is an observation target (measurement points are at least three), and a region of 13125 μm ² (140 μm × 93.75 μm) is laser microscope: VK-8700 Name, manufactured by Keyence Corporation) at a magnification of 100 times. In the observation region, the length direction of 140 μm is parallel to the longitudinal direction of the developing roller 1, and the length direction of 93.75 μm is parallel to the circumferential direction of the developing roller 1.
The number of projections 4a based on fine particles in the observation region observed in this way is counted. The number of convex portions counted at each measurement point is averaged to obtain the number of convex portions in the region.
Here, the convex part 4a in the observation region can be discriminated by binarization using particle analysis software.

  The number of convex portions can be set in the above range depending on the content of fine particles contained in the coating layer 4 and the like.

Covering layer 4, to the total area _{S A,} the surface area ratio of the surface area _{S T} of the convex portion 4a _(S T / S _A) is preferably in the range of 0.05 to 0.2. When the surface area ratio (S _T / S _A ) is within this range, both developer transportability and durability can be achieved at a higher level. The surface area ratio (S _T / S _A ) is preferably 0.05 to 0.18, more preferably 0.05 to 0.15, in that the developer transportability and durability are further improved. preferable.

In the present invention, the surface area ratio (S _T / S _A ) is a value measured and calculated as follows.
The surface is observed as described above to obtain a two-dimensional image of the surface of the observation region. This two-dimensional image is binarized (condition: binarization by option software, illumination, focus, and threshold are all set to automatic adjustment). It counts the total number of pixels in the observation area, and calculates the total area S _A from the number of the pixels. In the same manner, to calculate the total surface S _T of the convex portion 4a from the number of pixel regions showing a protrusion 4a. The surface area ratio (S _T / S _A ) is calculated by dividing the surface area S _T by the area S _A.

The surface area ratio (S _T / S _A ) can be set in the above range depending on the content of fine particles contained in the coating layer 4 and the average particle diameter.

The content of the fine particles in the coating layer 4 is preferably 0.1 to 30 parts by weight, more preferably 1 to 25 parts by weight, and 2 to 20 parts by weight with respect to 100 parts by weight of the base resin. More preferably, it is a part. When the content is within the above range, the number of convex portions, and further the surface area ratio (S _T / S _A ) can be set within the above range.

The coating layer 4 (developing roller 1) has a ten-point average roughness Rz of 5.5 μm or less. As a result, the occurrence of toner filming can be suppressed for a long time, and the amount of filming can be reduced. In this respect, the ten-point average roughness Rz of the coating layer 4 is preferably 0.5 to 5.5 μm, more preferably 1 to 5.5 μm, and 2 to 5.5 μm. Further preferred.
The ten-point average roughness Rz is set in accordance with JIS B0601-1984 by setting the developing roller 1 on a surface roughness meter (trade name “590A”, manufactured by Tokyo Seimitsu Co., Ltd.) equipped with a measurement probe having a tip radius of 2 μm. The measurement length is 2.4 mm, the cut-off wavelength is 0.8 mm, and the cut-off type Gaussian is used as an average value of values measured using at least three points as measurement points. The measurement positions are at least three points on both ends and the center of the coating layer 4 within about 200 mm in the center in the axial direction.
The ten-point average roughness Rz can be set in the above range depending on the average particle diameter or content of the fine particles.

  The coating layer 4 may or may not have conductivity as long as the developing roller 1 has conductivity, but preferably has conductivity. The conductivity of the coating layer 4 can be imparted, for example, by adding a conductivity imparting agent to the resin composition described later.

  The covering layer 4 preferably has a layer thickness of 10 nm to 20 μm, and more preferably has a layer thickness of 100 nm to 10 μm.

The developing roller of the present invention is not limited to the developing roller 1 as a preferable example, and various modifications can be made without departing from the object of the present invention.
For example, as long as the developing roller of the present invention includes a shaft body, a rubber elastic layer, and a coating layer, other configurations are not particularly limited. For example, the developing roller of the present invention may have an intermediate layer such as an adhesive layer or a primer layer between the shaft body and the rubber elastic layer or between the rubber elastic layer and the coating layer. Moreover, you may have a surface layer on the surface of a coating layer so that it may mention later.

As the surface layer, layers having various functions can be appropriately provided. For example, a surface layer having releasability with respect to toner particles or lubricity with respect to a blade in contact therewith can be mentioned.
Such a surface layer has only to have a predetermined function, and preferably contains at least one of Si element and fluorine element.
Examples of the surface layer containing Si element include a surface layer formed of a material containing Si element. Examples of the material containing Si element include a silicone graft polymer-containing urethane, an acrylic silicone resin-containing urethane, a silicone-based leveling agent-containing urethane, a silicone oil-containing urethane, or a silane coupling agent.
Examples of the surface layer containing elemental fluorine include a surface layer formed of a material containing elemental fluorine. Examples of the material containing elemental fluorine include urethane of fluorine polyol and isocyanate, fluorine-containing surfactant-containing urethane, acrylic fluororesin-containing urethane, and fluorine-containing microbead-containing urethane such as PTFE beads.
Examples of the surface layer containing Si element and fluorine element include a surface layer formed of a material containing Si element and fluorine element. Examples of the material containing Si element and fluorine element include a surface layer formed of a urethane polyol and a hydroxyl group-containing acrylic silicone resin graft resin on urethane.

The Si element and the fluorine element contained in the surface layer can be identified as follows.
That is, the test piece obtained by collecting the surface layer from the developing roller is analyzed by X-ray photoelectron spectroscopy (ESCA). Analyze the type of element detected.

The developing roller of the present invention forms a coating layer containing fine particles, and preferably by setting the surface area ratio (S _T / S _A ) and the ten-point average roughness Rz within a predetermined range as described above. Manufactured.
A method of manufacturing the developing roller 1 will be described, but the present invention is not limited to this.

  Specifically, first, the shaft body 2 is prepared or manufactured. The shaft body 2 is made into a rod-like body by a known method using the above material. The shaft body 2 may be cleaned, degreased, primer-treated, etc. on its outer peripheral surface as desired.

Next, a rubber elastic layer is formed on the outer periphery of the shaft body 2.
The rubber composition forming the rubber elastic layer is not particularly limited, but among the above, a silicone rubber composition is preferable, and a silicone rubber composition containing an organopolysiloxane and a conductivity imparting agent is more preferable.
The conductivity imparting agent is not particularly limited as long as it has conductivity, and examples thereof include conductive powders such as conductive carbon, rubber carbons, metals, and conductive polymers.
The silicone rubber composition may contain various additives. Such additives include, for example, auxiliary agents such as chain extenders and crosslinking agents, catalysts, dispersants, foaming agents, anti-aging agents, antioxidants, fillers, pigments, colorants, processing aids, softening agents. Agents, plasticizers, emulsifiers, heat resistance improvers, flame retardant improvers, acid acceptors, thermal conductivity improvers, mold release agents, solvents and the like.

  As a silicone rubber composition, an addition-curable millable conductive silicone rubber composition, an addition-curable liquid conductive silicone rubber composition, and an addition-reactive foamed silicone rubber composition in terms of expressing high adhesion to the shaft body 2 Among these, an addition curable liquid conductive silicone rubber composition is particularly preferable.

Addition-curing liquid conductive silicone rubber composition includes organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and at least two hydrogen atoms bonded to silicon atoms in one molecule. Organohydrogenpolysiloxane, an addition curing type liquid conductive material containing an inorganic filler having an average particle size of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ , a conductivity imparting agent and an addition reaction catalyst A functional silicone rubber composition. In the addition-curable liquid conductive silicone rubber composition, the organohydrogenpolysiloxane is 0.1 to 30 parts by mass, the inorganic filler is 5 to 100 parts by mass, and the conductivity-imparting agent with respect to 100 parts by mass of the organopolysiloxane. Is preferably 2 to 80 parts by mass, and the addition reaction catalyst is preferably 0.5 to 1,000 ppm with respect to the total mass of the organopolysiloxane and the organohydrogenpolysiloxane.

The addition-curable millable conductive silicone rubber composition has an average composition formula: RnSiO _{(4-n) / 2} (R may be the same or different, substituted or unsubstituted monovalent hydrocarbon groups, preferably A monovalent hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, and n is a positive number of 1.95 to 2.05). And an addition-curable millable conductive silicone rubber composition containing a conductive material other than those belonging to the filler. In the addition-curable millable conductive silicone rubber composition, the filler is preferably 11 to 39 parts by mass and the conductive material is preferably 2 to 80 parts by mass with respect to 100 parts by mass of the organopolysiloxane.
As this addition-curable millable conductive silicone rubber composition, the “addition-curable millable conductive silicone rubber composition” described in JP-A-2008-058622 can be used, and the contents described therein are described in the present specification. Embedded in the book.

The addition reaction type foamed silicone rubber composition contains a vinyl group-containing silicone raw rubber, a silica-based filler, a foaming agent, an addition reaction crosslinking agent, an addition reaction catalyst, a reaction control agent, and optionally an organic peroxide crosslinking agent and An addition reaction type foamed silicone rubber composition containing various additives may be mentioned. In this silicone rubber composition, the silica-based filler is 5 to 100 parts by mass, the foaming agent is 0.1 to 10 parts by mass, and the addition reaction crosslinking agent is 0.01 to 100 parts by mass of the vinyl group-containing silicone raw rubber. 20 parts by mass, the reaction control agent is preferably 0.1 to 2 parts by mass, and the addition reaction catalyst is preferably 1 to 1,000 ppm with respect to the entire composition.
As this addition reaction type foamed silicone rubber composition, the “addition reaction type foamed silicone rubber composition” described in JP-A-2008-076751 can be used, and the contents described therein are incorporated herein. .

  The rubber elastic layer is formed by disposing the rubber composition on the outer peripheral surface of the shaft body 2 and curing the rubber composition. The method for curing the rubber composition may be any method that can apply heat necessary for curing the rubber composition. Also, the method for forming the rubber elastic layer is not particularly limited, but continuous vulcanization by extrusion, pressing, molding by injection, or the like is preferable. The rubber elastic layer is preferably molded.

The heating temperature and heating time for curing the silicone rubber composition are preferably 100 to 500 ° C., particularly 120 to 300 ° C. in the case of an addition-curing type millable conductive silicone rubber composition, and are preferably several seconds to 1 hour. In particular, it is preferably 10 seconds to 35 minutes, and in the case of an addition-curable liquid conductive silicone rubber composition, it is preferably 100 to 300 ° C, particularly preferably 110 to 200 ° C, and 5 minutes to 5 hours. It is particularly preferably 1 to 3 hours, and in the case of an addition reaction type foamed silicone rubber composition, it is preferably 170 to 500 ° C., particularly preferably 200 to 400 ° C., and preferably several minutes to 1 hour, particularly 5 to 30. Preferably it is minutes. In this way, the silicone rubber composition is cured on the outer peripheral surface of the shaft body. If desired, the cured silicone rubber composition can be secondarily cured.
The surface of the rubber elastic layer is polished and ground as desired, and the outer diameter, surface state, and the like are adjusted. A primer layer may be formed on the outer periphery of the rubber elastic layer as desired. Further, the surface can be modified by plasma treatment, excimer treatment, UV treatment, corona treatment, itro treatment or flame treatment.

  The coating layer 4 can be formed by heat curing a fine particle-containing resin composition containing a thermoplastic resin or a thermosetting resin and fine particles on the outer peripheral surface of a rubber elastic layer or an optionally formed primer layer. . Also, a resin composition containing a thermoplastic resin or a thermosetting resin is applied to the outer peripheral surface of a rubber elastic layer or a primer layer formed as desired, and after being sprayed with fine particles, it is formed by heat curing. You can also. In the present invention, a method using a fine particle-containing resin composition is preferred.

The fine particle-containing resin composition contains fine particles. The fine particles are as described above, and the average particle size and content are appropriately determined so that the number of convex portions, the ten-point average roughness Rz, and preferably the surface area ratio (S _T / S _A ) is within the above range. Is done. The average particle diameter is as described above, and the preferred range is also the same. The content is the same as the content of the fine particles in the coating layer 4 and is as described above.

The fine particle-containing resin composition and the resin composition may contain a conductivity imparting agent and various additives. As the conductivity imparting agent and the additive, the same conductivity imparting agent and additive contained in the silicone rubber composition can be used, respectively.
When the coating layer 4 is formed of a urethane resin, the fine particle-containing resin composition and the resin composition contain a urethane preparation component that is a precursor for forming the polyester urethane resin. The urethane preparation component only needs to be able to form a polyurethane resin, and examples thereof include a mixture of polyester polyol and isocyanate. The urethane preparation component is preferably one capable of forming a polyester urethane resin, and examples thereof include a mixture of a polyester polyol and an isocyanate.

  The polyester polyol is not particularly limited, and examples thereof include compounds having two or more ester bonds and two or more hydroxyl groups in the molecule. Specifically, for example, ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, cyclohexanedimethanol, glycerin, 1,1,1-trimethylolpropane, and one or two other low molecular polyols A condensation polymer of at least one species with one or more of glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, dimer acid, other low molecular carboxylic acid and oligomeric acid, Alternatively, ring-opening polymers such as propionlactone, valerolactone, and caprolactone are exemplified.

As the polyester polyol, a polycarbonate polyol having good heat resistance and hardly hydrolyzing can be used. Even if a small amount of polyolefin polyol, polyether polyol, polyacryl polyol or the like is mixed to improve the performance, it can be used as long as it does not affect the heat of the surface treatment described later.
The polyester polyol can use 1 type (s) or 2 or more types.

The polyisocyanate may be any of various polyisocyanates commonly used in the preparation of polyurethane, for example, aromatic polyisocyanate, aliphatic polyisocyanate, alicyclic polyisocyanate, carbodiimide-modified polyisocyanate of these polyisocyanates, or These isocyanurate-modified polyisocyanates are exemplified.
Polyisocyanate can use 1 type (s) or 2 or more types.

Examples of the aromatic polyisocyanate 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.
Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornene diisocyanate methyl (NBDI), xylylene diisocyanate (XDI), and tetramethylxylylene diisocyanate (TMXDI). ) And the like.
Examples of the alicyclic polyisocyanate include transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), 4,4′-dicyclohexylmethane diisocyanate, and the like. Is mentioned.

  The mixing ratio in the mixture of polyol and polyisocyanate is not particularly limited, but usually the molar ratio (NCO / OH) of the hydroxyl group (OH) contained in the polyester polyol and the isocyanate group (NCO) contained in the polyisocyanate is It is preferable that it is 0.7-1.15. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10. From the viewpoint that hydrolysis of polyurethane can be prevented.

  In addition to the polyol and the polyisocyanate, the urethane adjusting component may be used in combination with an auxiliary agent usually used for the reaction between the polyol and the polyisocyanate, such as a chain extender and a crosslinking agent. Examples of the chain extender and the crosslinking agent include glycols, hexanetriol, trimethylolpropane and amines, carbodiimide, and the like.

The fine particle-containing resin composition and the coating of the resin composition include, for example, a fine particle-containing resin composition and a coating method for applying the resin composition, a dipping method in which a rubber elastic layer or the like is immersed in the fine particle-containing resin composition and the resin composition. And a known coating method such as a spray coating method in which the fine particle-containing resin composition and the resin composition are sprayed onto the rubber elastic layer or the like. These resin compositions may be applied as they are, and for example, alcohol resins such as methanol and ethanol, aromatic solvents such as xylene and toluene, and ester solvents such as ethyl acetate and butyl acetate. You may apply the coating liquid which added volatile solvents, such as these, or water.
The fine particle-containing resin composition and the method for curing the resin composition thus applied may be any method that can apply heat necessary for curing the fine particle-containing resin composition and the resin composition, for example, The method of heating with a heater is mentioned. The heating temperature is, for example, preferably 100 to 200 ° C, particularly 120 to 160 ° C, and the heating time is 10 to 120 minutes, particularly 30 to 60 minutes. In this way, the coating layer 4 can be formed.

The surface layer can be formed using the above-mentioned materials by the following method and conditions.
For example, the coating layer 4 and the surface layer can be formed by mixing the above-mentioned materials into the resin composition forming the coating layer 4 and applying and curing (drying) the rubber elastic layer.
Method for forming surface layer containing Si element:
The surface of the material containing Si element can be modified by blending silicone paint additives such as acrylic silicone resin, silane coupling agent, reactive silicone oil and leveling agent. For example, even when the molar ratio (NCO / OH) of the total mixture of polycarbonate diol and acrylic silicone polymer and polyisocyanate is 0.85 to 1.1, there is no change in operation if the compatibility of the resins is good. Can be molded under the same conditions.
Method for forming surface layer containing element F:
The surface of the material containing elemental fluorine can be modified by blending fluorine polyol, fluorine rubber, PTEF, PFA, fluorine leveling agent, fluorine polyol, acrylic fluorine polymer, fluorine surfactant, and the like. For example, when the molar ratio of polycarbonate diol to polyisocyanate (NCO / OH) is 0.85 to 1.1, molding is performed under the same conditions as described above without any change in operation if the compatibility of each resin is good as an additive. it can. Moreover, you may mix a fluororesin powder.
Conditions for forming surface layer containing Si element and F element:
Even when the molar ratio (NCO / OH) of the fluorine-based silicone graft resin is 0.85 to 1.1, if the compatibility of the resins is good, the molding can be performed under the same conditions as described above without any change in operation. In addition, a fluorine-based additive may be mixed in the blending of the material containing Si element if the compatibility is good. Moreover, you may mix a silicone type additive with the mixing | blending of the material containing a fluorine element.

  In this way, the developing roller 1 is manufactured.

In the developing roller 1 thus manufactured, the coating layer 4 contains fine particles having an average particle size of 5 to 15 μm as described above. Further, the convex portions 4a formed of the fine particles are irregularly present on the surface of the covering layer 4, and 100 or less are present in the region of 13125 μm ² . Furthermore, the ten-point average roughness Rz of the coating layer is 5.5 μm or less. Preferably, the surface area ratio (S _T / S _A ) is in the range of 0.05 to 0.2.
When such a developing roller 1 is mounted on an image forming apparatus, it is excellent in developer transportability and suppresses toner filming in the image forming apparatus, so that the image forming apparatus can produce a high-density and high-quality image. Can contribute to long-term formation (improvement of durability).

Next, an embodiment of the developing device of the present invention and the image forming apparatus of the present invention will be described with reference to FIG.
The image forming apparatus 10 is a tandem color image forming apparatus in which a plurality of image carriers 11B, 11C, 11M, and 11Y that are provided in the developing units B, C, M, and Y of the respective colors are arranged in series on the transfer conveyance belt 6. The developing units B, C, M, and Y are arranged in series on the transfer conveyance belt 6. The developing unit B includes an image carrier 11B such as a photosensitive member (also referred to as a photosensitive drum), a charging unit 12B such as a charging roller, an exposure unit 13B, a developing device 20B, and an image carrying belt 6. A transfer unit 14B that contacts the body 11B, such as a transfer roller, and a cleaning unit 15B are provided.

  The developing device 20B is an example of the developing device of the present invention, and includes the developing roller and the developer of the present invention as shown in FIG. Therefore, in this image forming apparatus 10, the developing roller 1 is mounted as a developer carrier 23B, 23C, 23M and 23Y, that is, as a developing roller. Specifically, the developing device 20B includes a housing 21B that houses a one-component non-magnetic developer 22B, a developer carrier 23B that supplies the developer 22B to the image carrier 11B, such as a developing roller, and a developer 22B. Developer amount adjusting means 24B for adjusting the thickness of the developer, for example, a blade. In the developing device 20B, as shown in FIG. 2, the developer amount adjusting means 24B is in contact with or in pressure contact with the outer peripheral surface of the developer carrier 23B. That is, the developing device 20B is a so-called “contact developing device”. The developing units C, M, and Y are basically configured in the same manner as the developing unit B. The same elements are denoted by the same reference numerals and symbols C, M, or Y indicating the respective units, and the description thereof is omitted. .

  In the image forming apparatus 10, the developer carrier 23B of the developing device 20B is disposed such that the surface thereof is in contact with or pressure contact with the surface of the image carrier 11B. Similarly to the developing device 20B, the developing devices 20C, 20M, and 20Y are arranged such that the surfaces of the developer carriers 23C, 23M, and 23Y are in contact with or pressed against the surfaces of the image carriers 11C, 11M, and 11Y. . That is, the image forming apparatus 10 is a so-called “contact image forming apparatus”.

  The fixing unit 30 is disposed on the downstream side of the developing unit Y. The fixing unit 30 includes a fixing roller 31, an endless belt support roller 33 disposed in the vicinity of the fixing roller 31, a fixing roller 31, and an endless belt support roller in a housing having an opening 35 through which the recording medium 16 passes. 33, an endless belt 36 wound around 33, and a pressure roller 32 disposed opposite to the fixing roller 31. The fixing roller 31 and the pressure roller 32 are in contact with or pressed against each other via the endless belt 36. It is a pressure heat fixing device which is supported in a freely rotatable manner. At the bottom of the image forming apparatus 10, a cassette 41 that houses the recording body 16 is installed. The transfer conveyance belt 6 is wound around a plurality of support rollers 42.

  Each of the developers 22B, 22C, 22M and 22Y used in the image forming apparatus 10 may be a dry developer or a wet developer as long as it can be charged by friction, and a non-magnetic developer or a magnetic developer. An agent may be used. One component non-magnetic black developer 22B, cyan developer 22C, magenta developer 22M and yellow developer 22Y are accommodated in the housings 21B, 21C, 21M and 21Y of the developing units.

  The image forming apparatus 10 forms a color image on the recording body 16 as follows. First, in the developing unit B, an electrostatic latent image is formed by the exposure unit 13B on the surface of the image carrier 11B charged by the charging unit 12B, and the black electrostatic latent image is developed by the developer 22B supplied by the developer carrier 23B. The image is developed. The black electrostatic latent image is transferred to the surface of the recording medium 16B when the recording medium 16 passes between the transfer means 14B and the image carrier 11B. Next, in the same manner as in the developing unit B, a cyan image, a magenta image, and a yellow image are superimposed on the recording medium 16 in which the electrostatic latent image is visualized as a black image by the developing units C, M, and Y, respectively. A color image is visualized. Next, the recording body 16 in which the color image is visualized is fixed to the recording body 16 by the fixing unit 30 as a permanent image. In this way, a color image can be formed on the recording medium 16.

  This developing device includes the developing roller 1 and is excellent in developer transportability and can suppress the occurrence of toner filming, thereby contributing to the formation of a high-density and high-quality image over a long period of time. Further, this image forming apparatus can form a high-density and high-quality image over a long period of time.

  The developing device and the image forming apparatus of the present invention are not limited to those described above, and various modifications can be made as long as the object of the present invention can be achieved.

  The image forming apparatus 10 is an electrophotographic image forming apparatus. However, in the present invention, the image forming apparatus is not limited to the electrophotographic system, and may be, for example, an electrostatic image forming apparatus. Good. Further, the image forming apparatus in which the developing roller of the present invention is disposed is not limited to a tandem color image forming apparatus in which a plurality of image carriers including developing units of respective colors are arranged in series on a transfer conveyance belt. A monochromatic image forming apparatus having a single developing unit, a four-cycle color image forming apparatus that sequentially repeats primary transfer of a developer image carried on an image carrier onto an endless belt, and the like may be used. The developer used in the image forming apparatus 10 is a one-component non-magnetic developer. However, in the present invention, a one-component magnetic developer or a two-component non-magnetic developer may be used. Or a two-component magnetic developer.

  The image forming apparatus 10 is a so-called “contact image forming apparatus”. In this invention, the image forming apparatus has a gap so that the surface of the developer carrying member does not contact the surface of the image carrying member. A so-called “non-contact type image forming apparatus” may be used.

Example 1
The developing roller 1 shown in FIG. 1 was manufactured as follows. The obtained developing roller 1 was measured for the following physical properties and evaluated for performance.
A silicone primer (trade name: Primer No. 4, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the surface of the shaft body 2 (SUM23, diameter 8 mm, length 282 mm), and then dried in a gear oven at 150 ° C. for primer treatment did.

Hydrophobized fumed silica (manufactured by Nippon Aerosil Co., Ltd.) having 100 parts by mass of dimethylpolysiloxane (D) (degree of polymerization: 300) capped with dimethylvinylsiloxy groups at both ends and a BET specific surface area of 110 m ² / g R-972) 1 part by mass, average particle size 6 μm, bulk density 0.25 g / cm ³ diatomaceous earth (F) (Oplite W-3005S, manufactured by Kitaaki Diatomaceous Earth) 40 parts by mass, and acetylene black (G ) (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) 5 parts by mass was put into a planetary mixer, stirred for 30 minutes, and then passed once through three rolls. This is returned to the planetary mixer again, and as a crosslinking agent, methyl hydrogen polysiloxane (E) having Si—H groups at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g) 2. 1 part by mass, 0.1 part by mass of ethynylcyclohexanol as a reaction control agent and 0.1 part of platinum catalyst (H) (Pt concentration 1%) are added, and the mixture is stirred and kneaded for 15 minutes to be an addition curing type. A liquid conductive silicone rubber composition was prepared.
The prepared addition-curable liquid conductive silicone rubber composition and the shaft pair were integrally molded, and a rubber elastic layer was formed on the outer periphery of the shaft body 2. This rubber elastic layer was solid with a thickness of 3 mm and had a JIS A hardness of 40.

A fine particle-containing urethane resin composition having the following composition was prepared.
-Polyol of urethane preparation component: 100 parts of carbonate diol (hydroxyl value = 56, trade name: Plaxel CD220, manufactured by Daicel)-Polyisocyanate of urethane preparation component: hexamethylene diisocyanate (trade name "Duranate TPA-B80E", Asahi Kasei Corporation 36 parts by mass / carbon black: (trade name “Toka Black # 5500”, manufactured by Tokai Carbon Co., Ltd.) 16.2 parts by mass (11.9 parts by mass with respect to 100 parts by mass of urethane preparation component)
・ 0.03 parts by mass of dibutyltin dilaurate (trade name “di-n-butyltin dilaurate”, Showa Chemical Co., Ltd.) ・ Urethane fine particles (trade name Art Pearl P-600T, average particle size 6 μm, manufactured by Negami Kogyo Co., Ltd.) 10 parts by mass (7.35 parts by mass with respect to 100 parts by mass of urethane preparation component)

A fine particle-containing urethane resin composition was applied to the outer periphery of the rubber elastic layer formed on the outer periphery of the shaft body 2 by a spray method and heated at 150 ° C. for 30 minutes to form a coating layer 4 having a layer thickness of 5 μm.
In this way, the developing roller 1 was manufactured.

(Example 2)
In Example 1, carbonate diol was changed to Plaxel 220EC (trade name, manufactured by Daicel Corporation), and urethane-based fine particle Art Pearl P-800T was replaced with Art Pearl P-400T (trade name, average particle diameter of 15 μm, manufactured by Negami Kogyo Co., Ltd.) A developing roller 1 was produced in the same manner as in Example 1 except that the above was replaced.

Example 3
In Example 2, the developing roller was the same as Example 2 except that the urethane-based fine particle Art Pearl P-800T was changed to Art Pearl RV-600T (trade name, average particle size 10 μm, manufactured by Negami Kogyo Co., Ltd.). 1 was produced.

Example 4
In Example 1, urethane-based fine particle Art Pearl P-800T was changed to Art Pearl RV-600T (trade name, average particle size 10 μm, manufactured by Negami Kogyo Co., Ltd.), and Modiper F206 (acrylic fluororesin, manufactured by NOF Corporation). The developing roller 1 was produced in the same manner as in Example 1 except that 1 part by mass of was added. In the obtained developing roller, the material containing fluorine element was transferred to the surface of the coating layer 4 to form a surface layer.

(Example 5)
In Example 3, fine particles were removed from the fine particle-containing urethane resin composition used in Example 3 in the coating layer 4 formed, and 2 masses of Cymac US-270 (trade name, silicone graft polymer, manufactured by Toagosei Co., Ltd.) was used. The developing resin of Example 5 was manufactured by coating and curing the urethane resin composition prepared by adding a part on the cover layer 4 to form a surface layer having a layer thickness of 2 μm. The surface layer contained a material containing Si element (silicone graft polymer).

(Example 6)
In Example 1, except that the content of the urethane-based fine particles was changed to 24 parts by mass (17.6 parts by mass with respect to 100 parts by mass of the urethane preparation component), the developing roller 1 was changed in the same manner as in Example 1. Manufactured.

(Comparative Example 1)
In Example 1, a developing roller was produced in the same manner as in Example 1 except that the urethane-based fine particle art pearl P-800T was changed to micropearl (trade name, average particle size 3 μm, manufactured by Sekisui Chemical Co., Ltd.). .

(Comparative Example 2)
In Example 3, the developing roller was produced in the same manner as in Example 3 except that the content of the urethane-based fine particles was changed to 20 parts by mass (14.7 parts by mass with respect to 100 parts by mass of the urethane preparation component). did.

(Comparative Example 3)
In Example 2, a developing roller was produced in the same manner as in Example 2 except that urethane fine particle art pearl P-800T was changed to Chemisnow MZ-16H (trade name, average particle size 16 μm, Soken Chemical). .

(Confirmation of convex part 4a)
In each of the manufactured developing rollers, it was confirmed from the micrograph of the cross section that the convex portions 4a existing on the surface of the coating layer 4 were formed of fine particles and the convex portions 4a were scattered.

(Measurement of the number of convex portions and the surface area ratio (S _T / S _A ))
In each manufactured developing roller, the number of convex portions present in the coating layer and the surface area ratio (S _T / S _A ) were measured by the above methods. The results are shown in Table 1.

(Measurement of ten-point average roughness Rz)
In each of the manufactured developing rollers, the ten-point average roughness Rz of the coating layer was measured by the above method. The results are shown in Table 1.

(Measurement of print density and filming amount)
About each manufactured developing roller, the printing density and the filming amount were measured as follows. The results are shown in Table 1.
The image forming apparatus used was model number: C610dn2 (Oki Data Co., Ltd.). As the developing roller of this image forming apparatus, each manufactured developing roller was mounted in the developing device. Next, a solid image was formed under conditions of 23 ° C. and 55%, and the printing evaluation was confirmed. The filming situation after printing 6000 sheets and the image quality after printing 6000 sheets (density step ratio between the initial printing formation portion and the final printing formation portion of solid printing) were evaluated. An X-Rite 500 spectral densitometer manufactured by X-Rite was used for the concentration measurement.
The print density was evaluated according to the following evaluation criteria. In this test, the print density is acceptable if the evaluation is A.
A: When the density step ratio is 96 to 100% and the printed dots are clean. B: When the density step ratio is 92 to 95% and there are other defects (printed dots are coarse). C : When the density step ratio is 91% or less and there are other problems

(Measurement of filming amount)
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 6000 sheets.
About filming evaluation, it evaluated by the following reference | standard by the mass of the transferred developer. In this test, the filming amount is acceptable when the evaluation is B.
A: 0 to 0.003 mg
B: 0.004 to 0.006 mg
C: 0.007 mg or more

From the results in Table 1, the following was found.
Each of the developing rollers of Examples 1 to 6 had irregular convex portions 4a on the surface, and satisfied the average particle diameter, the number of convex portions, and the ten-point average roughness Rz of the urethane-based fine particles. These developing rollers are excellent in print density (developer transportability), can suppress the amount of toner filming, and exhibit high durability.

  On the other hand, Comparative Example 1 does not satisfy the average particle diameter and the number of convex portions of the urethane-based fine particles. As a result, the filming amount was large and the print density was inferior. This is thought to be caused by the number of particles and surface waviness due to thixotropy of the urethane resin composition. In Comparative Example 2, the ten-point average roughness Rz is not satisfied. As a result, the developer transport amount was large and fogging occurred. Comparative Example 3 does not satisfy the average particle diameter and ten-point average roughness Rz of the urethane-based fine particles. As a result, neither the print density nor the filming amount was satisfactory.

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft body 4 Cover layer 4a Convex part 6 Transfer conveyance belt 10 Image forming apparatus 11B, 11C, 11M, 11Y Image carrier 12B, 12C, 12M, 12Y Charging means 13B, 13C, 13M, 13Y Exposure means 14B, 14C, 14M, 14Y Transfer means 15B, 15C, 15M, 15Y Cleaning means 16 Recording body 20 Developing devices 21B, 21C, 21M, 21Y, 34 Housings 22B, 22C, 22M, 22Y Developers 23B, 23C, 23M, 23Y Development Agent carrier 24B, 24C, 24M, 24Y Developer regulating member 30 Fixing means 31 Fixing roller 32 Pressure roller 33 Endless belt support roller 35 Opening 36 Endless belt 41 Cassette 42 Support rollers B, C, M, Y Development unit

Claims (6)

A developing roller comprising a shaft body, a rubber elastic layer formed on the outer periphery of the shaft body, and a coating layer formed on the outer periphery of the rubber elastic layer;
The coating layer contains fine particles having an average particle diameter of 5 to 15 μm,
The surface of the coating layer has irregular protrusions formed of the fine particles, and the number of protrusions present in the 13125 μm ² region of the surface is 100 or less,
A developing roller having a ten-point average roughness Rz of the coating layer of 5.5 μm or less. Wherein relative to the total area _{S A} of the coating layer, the surface area ratio of the surface area _{S T} of the convex portion _(S T / _{S A)} is, the developing roller according to claim 1 in the range of 0.05 to 0.2.   The developing roller according to claim 1, wherein the coating layer has a surface layer on a surface thereof.   The developing roller according to claim 3, wherein the surface layer contains at least one of Si element and fluorine element.   The developing device provided with the developing roller of any one of Claims 1-4.   An image forming apparatus comprising the developing roller according to claim 1.

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