JP2016070996A - Conductive roller, developing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive roller that can prevent the occurrence of long period of filming, and a developing device and an image forming apparatus including the conductive roller.SOLUTION: There is provided a conductive roller that has an elastic layer and a resin layer formed on the outer periphery of the elastic layer, where the resin layer is formed of a cured product of a composition that contains a monomer component of a polymer different from a polymer forming the elastic layer and resin beads having a reactive group that reacts with the monomer component. Also provided are a developing device and an image forming apparatus including the conductive roller.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a conductive roller, a developing device, and an image forming apparatus, and more particularly to a conductive roller, a developing device, and an image forming apparatus that can prevent the occurrence of long-term filming.

Various types of image forming apparatuses using an electrophotographic system are employed in laser printers, copiers, video printers, facsimiles, and multifunctional machines of these. A developing system using a one-component nonmagnetic developer is one of the main developing systems of such an image forming apparatus.
In this developing method, a one-component non-magnetic developer is carried on the surface of a conductive roller, and then supplied from the conductive roller to an image carrier such as a photosensitive drum to reveal an electrostatic latent image. In this development system, in order to supply the one-component nonmagnetic developer to the image carrier as desired, the one-component nonmagnetic developer is charged to an appropriate charge amount, and the developer layer has an appropriate thickness. As described above, it is important to support the surface of the conductive roller. In order to adjust the charge amount and thickness of the one-component non-magnetic developer as desired, the surface roughness that affects both the developer conveying force and the charge amount is set appropriately in the conductive roller. It is effective to do.

  As a method of adjusting the surface roughness of such a conductive roller, a method of incorporating particles into the conductive roller can be mentioned. For example, those using acrylic resin particles, polyurethane resin particles, silicone resin particles, silica particles, fluororesin particles, nylon particles, etc. as fine particles (Patent Documents 1 and 2), specific crosslinked polyurethane associated with the particle size of the developer Those using resin particles (Patent Document 3), those using polyurethane resin particles whose surfaces are coated with inorganic fine particles containing silicon, titanium or aluminum (Patent Document 4), those using silica-coated polyurethane urea particles (Patent Document 5) ) And the like.

JP 2010-276953 A JP-A-2005-352381 Japanese Patent No. 4815619 JP 2012-103581 A JP 2012-181226 A

  As described in Patent Documents 1 to 5, when an image forming apparatus equipped with a conductive roller containing particles is used continuously or intermittently for a long period of time, the developer is transmitted from the conductive roller after a long period of operation. Phenomenon (sometimes referred to as long-term filming) occurs that melts due to heat generated or frictional heat with a blade or the like and adheres to the surface of the conductive roller.

  However, Patent Documents 1 to 5 do not discuss any measures for preventing long-term filming.

  An object of the present invention is to provide a conductive roller capable of preventing the occurrence of long-term filming, and a developing device and an image forming apparatus provided with the conductive roller.

The object of the present invention has been achieved by the following means.
(1) A conductive roller having an elastic layer and a resin layer formed on the outer periphery of the elastic layer,
Curing of a composition for forming a resin layer, wherein the resin layer contains a monomer component of a polymer different from the polymer forming the elastic layer, and resin beads having a reactive group that reacts with the monomer component A conductive roller made of material.
(2) The conductive roller according to (1), wherein the resin beads have an average particle diameter of 1 to 40 μm.
(3) The conductive roller according to (1) or (2), wherein 1 to 90 of the resin beads are dispersed in a 35 μm × 50 μm region of the resin layer.
(4) The conductive roller according to any one of (1) to (3), wherein the sliding angle is 1 to 70 °.
(5) The conductive roller according to any one of (1) to (4), wherein the elastic layer is formed of polysiloxane and the resin layer is formed of polyurethane.
(6) The conductive roller according to any one of (1) to (5), wherein the reactive group is a blocked isocyanate group.
(7) A developing device comprising the conductive roller according to any one of (1) to (6) as a developing roller.
(8) An image forming apparatus comprising the conductive roller according to any one of (1) to (6) as a developing roller.
In the present invention, the polymer includes a copolymer in addition to the homopolymer.

  According to the present invention, a composition comprising a monomer component of a polymer different from the polymer forming the elastic layer, and resin beads having a reactive group that reacts with the monomer component forming the resin layer. It has a resin layer formed of a cured product, and resin beads do not fall off from the resin layer for a long time. As a result, the developer is not accumulated in the part where the developer has fallen off, and is not melted by heat transmitted from the conductive roller or frictional heat with the blade or the like. Therefore, it becomes difficult for the developer to adhere to the surface of the resin layer. Therefore, the conductive roller of the present invention can suppress long-term filming. Further, the developing device provided with the conductive roller of the present invention can contribute to the image forming apparatus forming an image having excellent image quality over a long period of time. Furthermore, the image forming apparatus of the present invention includes the conductive roller of the present invention, and can form an image having excellent image quality over a long period of time.

FIG. 1 is a front view showing an example of the conductive 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.

An example of the conductive roller of the present invention will be described.
The conductive roller 1 which is an example of the conductive roller of this invention is provided with the shaft body 2, the elastic layer 3, and the resin layer 4, as FIG. 1 shows.

The conductive roller 1, that is, the resin layer 4, preferably has a slip angle of 1 to 70 °, and particularly preferably 1 to 50 °. Thus, the resin layer 4 has a smaller sliding angle than a conventional conductive roller (sliding angle exceeding about 70 °), and if it is in the above range, the tack (adhesiveness) of the surface of the resin layer 4 is reduced. The developer does not adhere firmly and is easily detached. As a result, it is possible to suppress the occurrence of filming (sometimes referred to as initial filming) before dropping the resin beads.
The slip angle is obtained as follows. That is, a base on which a PET film is laid is disposed horizontally (at an angle of 0 ° with respect to the horizontal plane), and the longitudinal direction of the base and the axial direction of the conductive roller 1 are parallel to each other on the base. The conductive roller 1 is placed. With the one end in the longitudinal direction of the base fixed, the other end is raised to gradually tilt the base, and the base when the conductive roller 1 starts to slide toward the one end The angle formed with the horizontal plane is defined as the slip angle.
The sliding angle can be adjusted to an appropriate value depending on the content of the resin beads or the thickness of the resin layer 4.

The conductive roller 1, that is, the resin layer 4, has the following surface characteristics.
(1) The average interval Sm between the irregularities is preferably 2 to 300 μm, particularly preferably 40 to 250 μm. When the average interval Sm of the unevenness is in the above range, the developer transportability is excellent. Moreover, initial filming can be reduced.
(2) The arithmetic average roughness Ra is preferably 0.1 to 6.0 μm, particularly preferably 0.4 to 3.5 μm. When the arithmetic average roughness Ra is in the above range, the developer transportability is excellent. Moreover, initial filming can be reduced.
(3) The skewness Rsk of the contour curve is preferably −1.0 to 2.0 μm, and more preferably −1.0 to 1.0 μm. When Rsk is in the above range, the developer transportability is excellent. Moreover, initial filming can be reduced.
Any of the surface characteristics (1) to (3) can be adjusted to an appropriate value depending on the particle diameter and content of the resin beads and the thickness of the resin layer 4.

  The surface characteristics (1) to (3) are all in accordance with JIS B0601-1994, with 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 conductive roller provided with the resin layer 4 is set, and the average value of the values measured with at least three points as measurement points by a measurement length of 2.4 mm, a cutoff wavelength of 0.8 mm, and a cutoff type Gaussian is set.

  If the electroconductive roller 1 is provided with the elastic layer 3 and the resin layer 4, another structure will not be specifically limited. For example, the conductive roller of the present invention may have an intermediate layer such as an adhesive layer or a primer layer disposed between the shaft body and the elastic layer or between the elastic layer and the resin layer 4. .

  The conductive roller 1 may or may not include the shaft body 2. When the conductive roller 1 includes the shaft body 2, it is preferable that the shaft body 2 includes basically the same shaft body as that of a conventionally known conductive roller. The shaft body 2 is a so-called “core metal” made of, for example, iron, aluminum, stainless steel, brass, or the like, and preferably has good conductive properties. 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 elastic layer 3 is not particularly limited, but is made of silicone rubber, urethane rubber, ethylene-propylene-diene rubber, or the like made of each polymer such as polysiloxane, polyurethane, ethylene-propylene-diene copolymer, and the like. Formed on the outer peripheral surface of the body 2. Silicone rubber is preferable as the rubber forming the elastic layer 3 in terms of durability and the like. The rubber and copolymer forming the elastic layer 3 will be described later. The elastic layer 3 may contain a conductivity imparting agent, various additives, and the like, which will be described later.

  The elastic layer 3 preferably has a JIS A hardness of 20 to 45. When the elastic layer 3 has a JIS A hardness (JIS K 6301) of 20 to 45, the contact area between the conductive roller 1 and the contacted body can be increased. The elastic layer 3 has a thickness of 1 to 30 mm in that a uniform nip width between the contacted body and the elastic layer 3 can be secured in a contact state with the contacted body. Is preferable, and it is especially preferable that it is 5-20 mm.

  The resin layer 4 includes a monomer component of a polymer different from the polymer forming the elastic layer 3, and a cured product of the composition described later, which contains resin beads having a reactive group that reacts with the monomer component. It is formed on the outer peripheral surface of the elastic layer 3 by (reactant).

  The resin layer 4 is usually formed as a thin layer, and specifically has a layer thickness of 2 to 50 μm, more preferably 10 to 30 μm. For example, when the elastic layer 3 is formed of silicone rubber, it is preferable to have a certain thickness to prevent the silicone oligomer from bleeding out on the surface of the resin layer 4. The layer thickness is preferably 2 to 50 μm, and more preferably 5 to 30 μm. When the resin layer 4 having the layer thickness in the above range is provided, the silicone oligomer leaking from the elastic layer 3 bleeds on the surface of the conductive roller 1 even if the conductive roller 1 includes the elastic layer 3. It is difficult to out, and it is difficult to contaminate a member with which the conductive roller 1 contacts, for example, an image carrier. It can also contribute to the formation of high quality images.

  The resin layer 4 is made of, for example, a resin of each polymer of polyurethane. A monomer component (also referred to as a urethane preparation component) capable of forming polyurethane will be described later.

  In the resin layer 4, a reactive group included in the resin beads described later reacts with at least one of monomer components capable of forming a polymer, and the resin beads chemically bond with the polymer forming the resin layer 4. doing. That is, the resin beads react with the polymer forming the resin layer 4 to be integrated. Therefore, it is possible to prevent the resin beads from falling off over a long period, which is considered to be a cause of long-term filming.

The resin beads are dispersed or scattered in the resin layer 4. At this time, 1 to 90 resin beads are preferably dispersed in a 35 μm × 50 μm (1750 μm ² ) region of the resin layer 4, particularly preferably 1 to 40 resin beads. When the number of dispersed resin beads is in the above range, an effect that the developer transportability is excellent can be obtained.
Here, the dispersion number of the resin beads, that is, the dispersion state is obtained as follows. That is, an area of 1750 μm ² (35 μm × 50 μm) on the surface of the resin layer 4 at three positions in the axial direction of the conductive roller (center and both ends (area 20 mm from the edge toward the center)) is scanned. Using an electron microscope (trade name: JSM-6010LA, manufactured by JEOL Ltd.), observation is performed under conditions of a measurement magnification of 2500 times, an acceleration voltage of 10 kV, and a spot size SS45, and each image is photographed. It can be obtained by counting the number of resin beads in each photographed micrograph and arithmetically averaging these. The number of dispersed resin beads can be adjusted to an appropriate value depending on the content of the resin beads.

  The particle size of the resin beads is preferably 1 to 40 μm, and more preferably 3 to 15 μm. When the particle size of the resin beads is in the above range, the developer transportability is excellent. Here, the particle size of the resin beads is obtained as follows. That is, an image is taken by observing the surface of the conductive roller 1 with a color 3D laser microscope (VK-9700 / VK-8700) manufactured by KEYENCE. The presence of the resin beads is confirmed from the observed image, and the particle size of the resin beads is measured using analysis software (shape analysis application VK-H1A1 / VK-H2A1, particle analysis application VK-H1G1, both manufactured by KEYENCE). .

  The resin beads only have to have a particle diameter in the above range, but the ratio of the average particle diameter to the thickness of the resin layer 4 described later (average particle diameter / thickness) is 0.1 to 5. Preferably, it is 0.1-2. When this ratio is within the above range, the developer transportability is excellent.

  The resin beads preferably have a reactive group on the surface that reacts with the monomer component of the polymer forming the resin layer 4. In the resin bead, the part to which the reactive group is bonded is called a bead body. That is, this resin bead has a bead body, and preferably at least a reactive group on the surface of the bead body.

Although the material which forms a bead main body is not specifically limited, An organic compound is preferable and an organic high molecular compound (polymer) is preferable. Examples of the organic polymer compound include polymers such as polyurethane, PMMA (polymethyl methacrylate), and amino resin. Here, the amino resin means a resin made of a copolymer obtained by a condensation reaction between an amino group-containing compound such as urea or melamine and an aldehyde. Examples thereof include a urea resin obtained by condensation of urea and formaldehyde, and a melamine resin obtained by condensation of melamine and formaldehyde.
Among these, since polyurethane has low hardness, it is preferable in that the stress applied to the developer can be reduced and the damage of the developer can be reduced.

The reactive group is not particularly limited as long as it is a group that reacts with at least one monomer component of the polymer that forms the resin layer 4, and is appropriately selected according to the type of polymer that forms the resin layer 4. Is done. For example, the reactive group includes isocyanate (including a blocked isocyanate group), a hydroxyl group, and the like.
Especially, when the resin layer 4 consists of polyurethane, a blocked isocyanate group is preferable.

Hereinafter, resin beads having a blocked isocyanate group on the surface (referred to as polyurethane beads) will be described.
Polyurethane beads are particles composed of a bead body made of a urethane resin and an organic group containing a blocked isocyanate group that binds to the bead body. The polyurethane resin that forms the bead main body may be a known urethane resin, and includes, for example, a polyol and a polyisocyanate. Polyols include polyester-based polyols, polyether-based polyols, acrylic polyol-based polyols, etc., and polyisocyanates include aromatic, aliphatic, and alicyclic polyisocyanates, particularly trifunctional or higher functional polyisocyanates. Can be mentioned.

  The urethane resin that forms the bead body preferably has a glass transition temperature Tg of −50 to 30 ° C. The glass transition temperature is more preferably −50 to −20 ° C. in that stress applied to the developer can be reduced to reduce damage to the developer. The glass transition temperature can be measured by a method defined in JIS K 7121 using a differential scanning calorimeter DSC8230L (manufactured by Rigaku Corporation). This glass transition temperature can be adjusted by appropriately selecting an isocyanate, a polyol and the like constituting the urethane resin particles.

  The organic group containing a blocked isocyanate group may be only the blocked isocyanate group, or may be a group having a blocked isocyanate group at the terminal or side chain. The blocking agent for protecting the isocyanate group can be used without particular limitation as long as it is desorbed from the isocyanate by heat and is liberated, for example, a lactam blocking agent, an oxime blocking agent, a phenolic blocking agent. A blocking agent, an alcohol-type blocking agent, etc. are mentioned.

  The content of isocyanate groups in the polyurethane beads is preferably 1 to 5% by mass. When the isocyanate group content is in the above range, it can be firmly bonded to the monomer component of the polymer forming the resin layer 4. Isocyanate group content can be adjusted with the compounding quantity of a polyol.

The polyurethane beads preferably have a 10% microcompression strength of 10 to 15 MPa, more preferably 11 to 14 MPa, and even more preferably 12 to 13 MPa. When the 10% minute compressive strength is in the above range, the polyurethane beads become excessively flexible, and the resin layer 4 is not excessively stressed during driving, and the resin layer 4 can be prevented from being damaged. The 10% micro compressive strength is measured in an environment where the room temperature is 23 ° C. and the relative humidity is 55%, and the polyurethane beads to be measured are left in the same environment for 24 hours before the measurement. The particle size d (mm) of the polyurethane beads is measured with a digital microscope attached to an ultra-micro hardness measuring device (trade name: “ENT-1100”, manufactured by Elionix). Next, a flat indenter with a 20 μm square tip is attached to the ultra-micro hardness measuring apparatus, and a load of 0.001 N per second is added and applied. Compression is performed until the particle size in the direction in which the load is applied is reduced by 10% from the diameter d (mm), and the load P (N) applied to the planar indenter at this time is measured. The load P (N) applied to the planar indenter is substituted into the formula: E = 2.8 P / πd ² (MPa) to determine the 10% compression hardness E (MPa) of the polyurethane beads. The 10% micro compressive strength can be adjusted by the temperature at which the blocking agent is desorbed from the isocyanate.

As the polyurethane beads, commercially available products may be used, or they may be appropriately synthesized.
Examples of commercially available products include “Art Pearl” (trade name) manufactured by Negami Kogyo Co., Ltd. Specifically, “RU-600T” (isocyanate group content 5 mass%, 10% fine compression strength 12.7 MPa, average particle size 10 ± 2 μm), “RV-600T” (isocyanate group content 5 mass%, 10% fine compression strength 12.2 MPa, average particle size 10 ± 2 μm) and the like.
When synthesizing polyurethane beads, examples of the synthesis method include a method in which a urethane prepolymer containing a blocked isocyanate group is dispersed in water and heated.

The resin beads may be used alone or in combination of two or more.
As long as the resin beads are in the above dispersed state, the content in the resin layer 4 is not particularly limited. For example, the ratio of 8 to 40 parts by mass with respect to 100 parts by mass of the polymer forming the resin layer, More preferably, it is 10-35 mass parts. When the content ratio of the resin beads is in the above range, the developer transportability is excellent.

The resin layer 4 may contain a conductivity imparting agent, various additives, and the like, which will be described later.
The resin layer 4 may or may not have conductivity as long as the conductive roller 1 has conductivity, but preferably has conductivity. The conductivity of the resin layer 4 can be adjusted by, for example, the content of a conductivity imparting agent in the composition described later.

  The conductive roller of the present invention can be manufactured by forming an elastic layer on the outer peripheral surface of the shaft body and further forming the resin layer 4 on the outer peripheral surface of the elastic layer. The manufacturing method will be described by taking the conductive roller 1 as an example.

  In order to manufacture the conductive roller 1, first, the shaft body 2 is prepared. For example, the shaft body 2 is prepared in a desired shape by a known method. The shaft body 2 may be coated with a primer before the elastic layer 3 is formed. Although there is no restriction | limiting in particular as a primer apply | coated to the shaft body 2, The resin similar to the material which forms the primer layer which adheres or adheres the said elastic layer 3 and the resin layer 4, and a crosslinking agent are mentioned. The primer is dissolved in a solvent or the like as desired, and is applied to the outer peripheral surface of the shaft body according to a conventional method such as a dipping method or a spray method.

The elastic layer 3 is formed by heat-curing the following elastic layer forming composition on the outer peripheral surface of the shaft body 2. For example, the elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The elastic layer forming composition may be cured by any method that can apply heat necessary for curing the elastic layer forming composition. The elastic layer 3 may be formed by continuous vulcanization, extrusion, or injection by extrusion. There is no particular limitation such as molding.
For example, when the elastic layer forming composition is the following addition curable millable conductive silicone rubber composition, for example, extrusion molding or the like can be selected, and the elastic layer forming composition can be added curable liquid conductive. In the case of the conductive silicone rubber composition, for example, a molding method using a mold can be selected. In the case of an addition-curable millable conductive silicone rubber composition, the heating conditions are preferably 100 to 500 ° C., particularly 120 to 300 ° C., and the time is several seconds to 1 hour, particularly 10 seconds to 35 minutes. In the case of an addition curable liquid conductive silicone rubber composition, it is preferably 100 to 300 ° C., particularly 110 to 200 ° C., and the time is 5 minutes to 5 hours, particularly 1 to 3 hours. In addition, in the case of an addition-curable millable conductive silicone rubber composition, if necessary, the curing conditions are about 100 to 200 ° C. for about 1 to 20 hours, and in the case of an addition-curable liquid conductive silicone rubber composition. Secondary vulcanization may be performed at 120 to 250 ° C. under curing conditions for about 2 to 70 hours. The composition for forming an elastic layer can be easily foamed and cured by a known method to easily form a sponge-like elastic layer having bubbles.

The polymer for forming the elastic layer 3 is not particularly limited, and is selected from, for example, each of the above polymers, and polysiloxane is preferable.
The elastic layer 3 is preferably formed of an elastic layer layer-forming composition containing a polymer that forms the elastic layer 3 or a monomer component that can form the polymer, and various additives. When the polymer is polysiloxane, it is preferable to use as the elastic layer forming composition a silicone rubber composition containing a polysiloxane monomer component, a conductivity-imparting agent, and optionally various additives.
The monomer component of polysiloxane is not particularly limited, and examples thereof include siloxanes having at least one organic group (monoorganosiloxane, diorganosiloxane, triorganosiloxane), hydrogensiloxane, tetrahydroxysiloxane, and the like. .

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.
Various 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, Examples thereof include a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent.

  Preferred examples of the silicone rubber composition include addition curable millable conductive silicone rubber compositions, addition curable liquid conductive silicone rubber compositions, and the like.

Examples of the addition curable millable conductive silicone rubber composition include (A) average composition formula: RnSiO _{(4-n) / 2} (R may be the same or different, substituted or unsubstituted monovalent carbonization A hydrogen group, 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). An addition-curable millable conductive silicone rubber composition containing polysiloxane, (B) filler, and (C) a conductive material other than those belonging to the component (B).
In the addition-curable millable conductive silicone rubber composition, the filler (B) is 11 to 39 parts by mass and the conductive material (C) is 2 to 80 parts by mass with respect to 100 parts by mass of the organopolysiloxane (A). preferable.
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 curable liquid conductive silicone rubber composition comprises (D) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (E) hydrogen bonded to silicon atoms in one molecule. An organohydrogenpolysiloxane containing at least two atoms; (F) 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 ; and (G) a conductive material. An addition-curable liquid conductive silicone rubber composition containing a property-imparting agent and (H) an addition reaction catalyst.
In the addition-curable liquid conductive silicone rubber composition, the organohydrogenpolysiloxane (E) is 0.1 to 30 parts by mass and the inorganic filler (F) is 5 with respect to 100 parts by mass of the organopolysiloxane (D). ~ 100 parts by mass, the conductivity imparting agent (G) is preferably 2 to 80 parts by mass, and the addition reaction catalyst (H) is 0 with respect to the total mass of the organopolysiloxane (D) and the organohydrogenpolysiloxane (E). .5 to 1,000 ppm is preferred.
As this addition-curable liquid conductive silicone rubber composition, the “addition-curable liquid conductive silicone rubber composition” described in JP-A-2008-058622 can be used, and the contents described therein are described in this specification. Embedded in the book.

  The elastic layer 3 formed in this way has its surface polished and ground as desired to adjust the outer diameter, surface state, and the like. In addition, a primer layer may be formed on the outer peripheral surface of the elastic layer 3 before forming the coat layer 4.

  Further, before the resin layer 4 is formed, the elastic layer 3 can be subjected to a surface treatment such as excimer UV treatment to generate a hydroxyl group. When such a surface treatment is performed, the adhesion between the elastic layer 3 and the resin layer 4 becomes high.

  The resin layer 4 is formed by coating the resin layer forming composition on the outer peripheral surface of the elastic layer 3 or the primer layer formed as desired, and then heat-curing the applied resin layer forming composition. And formed by a cured product of the resin layer forming composition. Application of the resin layer forming composition is, for example, a coating method of applying a coating solution of the resin layer forming composition, a dipping method of immersing the elastic layer 3 or the like in the coating solution, and applying the coating solution to the elastic layer. This is performed by a known coating method such as a spray coating method for spraying on 3 etc. The resin layer forming composition may be applied as it is, or the resin layer forming composition may be applied to, for example, alcohols such as methanol and ethanol, aromatic solvents such as xylene and toluene, ethyl acetate and butyl acetate, etc. You may apply the coating liquid which added volatile solvents, such as these ester solvents, or water.

The method of curing the resin layer forming composition thus applied is the temperature at which the resin layer forming composition is cured and the temperature at which the resin beads react, for example, the polyurethane bead blocking agent is desorbed. Any method may be used as long as it is heated to a temperature equal to or higher than the heating temperature. As a result, when the resin beads are polyurethane beads, the isocyanate is regenerated and reacted with the polymer or monomer component, for example, the urethane preparation component, so that the polyurethane beads react with the polymer to become an integral body. A resin layer 4 is formed.
As a heating method, for example, a method of heating the elastic layer 3 or the like coated with the resin layer forming composition with a heater, or a method of heating the elastic layer 3 or the like coated with the resin layer forming composition under high humidity The method of leaving still is mentioned. The heating temperature when the resin layer forming composition is heat-cured is, for example, 100 to 200 ° C., particularly 120 to 160 ° C., and the heating time is preferably 10 to 120 minutes, particularly preferably 30 to 60 minutes. In addition, instead of coating, the resin layer forming composition was laminated on the outer peripheral surface of the elastic layer 3 or the primer layer by a known molding method such as extrusion molding, press molding, injection molding, or the like. Later, the laminated resin layer forming composition may be cured.

The polymer that forms the resin layer 4 is not particularly limited as long as it is a polymer different from the polymer that forms the elastic layer, and is selected from the above polymers, and polyurethane is preferred. When the polymer forming the elastic layer is polysiloxane, polyurethane is particularly preferable.
The resin layer 4 is preferably formed of a resin layer forming composition containing a polymer or a monomer component capable of forming a polymer and various additives. When the polymer is polyurethane, a urethane resin composition containing a urethane preparation component to be polyurethane, polyurethane beads having a blocked isocyanate group on the surface, preferably a conductivity imparting agent, and optionally various additives is a resin. Preferred as a layer forming composition.

  The urethane preparation component may be any component that can form polyurethane and can react with the reactive group of the resin beads. For example, the urethane preparation component is obtained by reacting a mixture of polyol and polyisocyanate, or polyol and polyisocyanate. Examples include prepolymers. Here, when a polymer is a polyurethane, the monomer component says a polyol and polyisocyanate.

The polyol in the mixture of polyol and polyisocyanate may be any of various polyols usually used for the preparation of urethane resins, and each polyol exemplified in the urethane resin particles is preferable. Similarly, the polyisocyanate in the mixture may be any of various polyisocyanates usually used for preparing urethane resins, and each polyisocyanate exemplified in the urethane resin particles is preferable. The polyisocyanate preferably has a molecular weight of 500 to 2000, more preferably 700 to 1500.
The mixing ratio of these in the mixture of polyol and polyisocyanate is not particularly limited. Usually, hydroxyl group (OH) contained in polyol and isocyanate group (NCO, block polyisocyanate contained in polyisocyanate can be liberated. The molar ratio (NCO / OH) to (isocyanate group) is preferably 0.7 to 1.15. This molar ratio (NCO / OH) is more preferably 0.85 to 1.10 in terms of preventing hydrolysis of the urethane resin.

  When the urethane resin preparation component is a mixture of a polyol and a polyisocyanate, it may contain an auxiliary agent usually used for the reaction between the polyol and the polyisocyanate, for example, a chain extender, a crosslinking agent and the like. Examples of chain extenders and crosslinking agents include glycols, hexanetriol, trimethylolpropane, and amines.

  The prepolymer as the urethane resin preparation component may be a prepolymer obtained by reacting the polyol and the polyisocyanate, and the molecular weight thereof is not particularly limited. If desired, the prepolymer can be obtained by reacting a polyol and a polyisocyanate by the one-shot method or the prepolymer method in the presence of the auxiliary agent.

  The urethane resin preparation component is preferably a mixture of polyol and polyisocyanate, particularly preferably a mixture of at least one polyol selected from polyether polyol and polyester polyol and polyisocyanate.

As the conductivity imparting agent, those described above can be used without any particular limitation.
Various additives are not particularly limited, for example, auxiliary agents such as chain extenders and crosslinking agents, dispersing agents, foaming agents, anti-aging agents, antioxidants, pigments, colorants, processing aids, softening agents, Examples thereof include a plasticizer, an emulsifier, a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent. These various additives may be additives that are usually used in urethane resin compositions, or may be additives that are specifically used depending on the application.

The resin beads are contained in the solid content of the resin layer forming composition, preferably at a rate of 30 to 100 parts by mass, more preferably at a rate of 30 to 80 parts by mass. When the content ratio of the resin beads is in the above range, the developer transportability is excellent.
When the conductivity imparting agent is contained, the content of the conductivity imparting agent is preferably 1 to 10 parts by mass, more preferably 2 to 4 parts by mass with respect to 100 parts by mass of the polymer or monomer component. .
Content of various additives is set suitably.

  The urethane resin composition can be prepared by mixing the above components by a conventional method.

  In this way, the conductive roller 1 can be manufactured.

  The conductive roller of the present invention is a cured product of a composition comprising a monomer component of a polymer different from the polymer forming the elastic layer, and resin beads having reactive groups that react with the monomer component By having the resin layer formed in (1), it is possible to prevent the resin beads from falling off from the resin layer over a long period of time, and it is possible to suppress the occurrence of long-term filming.

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.
As shown in FIG. 2, the image forming apparatus 10 includes 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 in series on the transfer conveyance belt 6. Therefore, 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 according to the present invention, and includes a conductive roller and a developer, for example, a positively charged developer according to the present invention, as shown in FIG. Therefore, in this image forming apparatus 10, the conductive 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”.
In the image forming apparatus 10, the developing units C, M, and Y are basically configured in the same manner as the developing unit B, and the same elements are denoted by the same reference numerals and symbols C, M, or Y indicating the respective colors. Description 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 in 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. ing. 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 in a housing 34 having an opening 35 through which the recording medium 16 passes. An endless belt 36 wound around a support roller 33 and a pressure roller 32 disposed opposite to the fixing roller 31 are provided, and the fixing roller 31 and the pressure roller 32 are in contact with or pressed against each other via the endless belt 36. Thus, the pressure heat fixing device is rotatably supported. 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. These developers 22B, 22C, 22M and 22Y are all preferably positively charged developers. Examples of positively charged developers include positively chargeable non-magnetic one-component polymer developers. Specifically, as the positively charged developer, a binder resin obtained by polymerizing or copolymerizing acrylic monomers or styrene monomers such as acrylic acid, alkyl (meth) acrylate having 1 to 4 carbon atoms, and the like. , A substantially spherical developer having developer particles composed of a colorant, a charge control agent and wax, and various external additives. Examples of the colorant include black, cyan, magenta, and yellow colorants. Examples of the charge control agent are copolymerizable with an ionic monomer having an ionic functional group such as an ammonium salt and an ionic monomer such as a styrene monomer or the acrylic monomer. Examples thereof include charge control resins obtained by copolymerization with monomers. Examples of the external additive include inorganic powders such as silica, aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide and other metal oxide powders, carbide powders, and metal salt powders. In order to positively charge the developer, the type and characteristics of the binder resin may be selected. If the binder resin is contained, the developer is positively charged.

  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.

  In the tandem type image forming apparatus 10, when the conductive roller 1 according to the present invention is used as the developer carrier 23, the resin beads do not fall off from the resin layer 4 of the conductive roller 1 for a long period of time, and the developer is the resin layer. 4 becomes difficult to adhere to the surface. Therefore, the developing device 20 can contribute to forming a high quality image over a long period of time. The tandem type image forming apparatus 10 including the conductive roller 1 can form a high quality image over a long period of time.

  The image forming apparatus 10 is an image forming apparatus such as a copying machine, a facsimile machine, or a printer. Although the image forming apparatus 10 has been described with reference to the example in which the conductive roller 1 according to the present invention is used as a developing roller as an example of the developer carrier 23, the conductive roller 1 according to the present invention is used as a developer supply roller. Even if the property roller 1 is used, a high-quality image can be similarly formed.

  The conductive roller, the developing device, and the image forming apparatus of the present invention are not limited to the above-described one embodiment, and various modifications are possible as long as the object of the present invention can be achieved.

  The conductive roller 1 according to the present invention may have another layer between the elastic layer 3 and the resin layer 4. Examples of the other layer include a primer layer that adheres or adheres the elastic layer 3 and the resin layer 4 to each other. Examples of materials for forming the primer layer include alkyd resins, phenol-modified / silicone-modified alkyd resin modified products, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenol resins, polyamide resins, urethanes. Examples thereof include resins and mixtures thereof. Moreover, as a crosslinking agent which hardens and / or bridge | crosslinks these resin, an isocyanate compound, a melamine compound, an epoxy compound, a peroxide, a phenol compound, a hydrogen siloxane compound etc. are mentioned, for example. The primer layer is formed with a thickness of 0.1 to 10 μm, for example.

  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 provided with the conductive roller according to the present invention is not limited to a tandem color image forming apparatus in which a plurality of image carriers having developing units of respective colors are arranged in series on a transfer conveyance belt. For example, a monochrome image forming apparatus provided with 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 may be used. The developer 22 used in the image forming apparatus 10 is a one-component nonmagnetic developer. However, in the present invention, the developer 22 may be a one-component magnetic developer or a two-component nonmagnetic developer. 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.

  The developing device in the image forming apparatus 10 is a so-called “contact type developing device”. In this invention, the developing device has a gap so that the developer amount adjusting means does not contact the outer peripheral surface of the developer carrier. It may be a so-called “non-contact type developing device” that is disposed.

Example 1
The shaft body 2 (made by SUM22, diameter 10 mm, length 275 mm) subjected to electroless nickel plating was washed with ethanol, and a silicone primer (trade name “Primer No. 16”, manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on the surface. ) Was applied. The primer-treated shaft body 2 was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body 2.

Next, 100 parts by mass of dimethylpolysiloxane (degree of polymerization: 300) blocked at both ends with dimethylvinylsiloxy groups, and hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (manufactured by Nippon Aerosil Co., Ltd., R -972) 1 part by mass, 40 parts by mass of diatomaceous earth (Oplite W-3005S, manufactured by Hokuaki Diatomite Co., Ltd.) having an average particle size of 6 μm and a bulk density of 0.25 g / cm ³ , and acetylene black (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 was returned to the planetary mixer again, and as a crosslinking agent, 2.1 parts by mass of methyl hydrogen polysiloxane having a Si—H group at both ends and side chains (polymerization degree 17, Si—H amount 0.0060 mol / g). Addition of 0.1 part by mass of ethynylcyclohexanol and 0.1 part of platinum catalyst (Pt concentration 1%) as reaction control agents, and stirring and kneading for 15 minutes, addition curable liquid conductive silicone rubber composition A product was prepared. The prepared addition-curable liquid conductive silicone rubber composition was molded on the outer peripheral surface of the shaft body 2 by liquid injection molding. In liquid injection molding, the addition-curable liquid conductive silicone rubber composition was cured by heating at 150 ° C. for 10 minutes. This molded body was polished to form an elastic layer having an outer diameter of 20 mm. The elastic layer 3 had a JIS A hardness of 43 °.

On the other hand, a urethane resin composition for forming the resin layer 4 having the following composition was prepared.
(A) Monomer component 1: Isocyanate (MDI, trade name “Coronate-HX”, manufactured by Nippon Polyurethane Industry Co., Ltd.) 18 parts by mass (B) Monomer component 2: Polyol (trade name “ON-F40”, Nippon Polyurethane Industry Co., Ltd.) 100 parts by mass (molar ratio (NCO / OH = 0.9))
(C) As polyurethane beads having blocked isocyanate groups on the surface, “RV-600T” (trade name, manufactured by Negami Kogyo Co., Ltd., isocyanate group content 5 mass%, 10% fine compression strength 12.2 MPa, average particle size 10 ± 2 μm, ratio of average particle diameter (average particle diameter / thickness of resin layer 4) 0.5, glass transition temperature 30 ° C.) 27 parts by mass (22.9 parts by mass relative to 100 parts by mass of urethane preparation component)
(D) 3 parts by mass of carbon black (trade name “Toka Black # 4500”, manufactured by Tokai Carbon Co., Ltd.) (E) dibutyltin dilaurate (trade name “di-n-butyltin dilaurate”, manufactured by Showa Chemical Co., Ltd.) 0.03 mass Part

  This urethane resin composition was applied to the outer peripheral surface of the elastic layer by a spray coating method, and heated at 160 ° C. for 30 minutes to form a resin layer 4 having a layer thickness of 20 μm. In this way, a conductive roller was manufactured.

(Examples 2 and 3)
Each conductive roller 1 is manufactured in the same manner as in Example 1 except that the content of polyurethane beads “RV-600T” is changed to the content shown in Table 1 (content relative to 100 parts by mass of urethane preparation component). did.

(Comparative Example 1)
Instead of polyurethane beads “RV-600T”, polyurethane beads “JB-800T (U5)” (trade name, manufactured by Negami Kogyo Co., Ltd., isocyanate group content 0% by mass, 10% fine compression strength 1.56 MPa, average particle size 7 μm A conductive roller was produced basically in the same manner as in Example 1 except that the average particle size ratio was 0.35 and the glass transition temperature was −52 ° C.

(Comparative Example 2)
Instead of polyurethane beads “RV-600T”, polyurethane beads “CE-800T (U13)” (trade name, manufactured by Negami Kogyo Co., Ltd., isocyanate group content 0 mass%, average particle size 10 μm, average particle size ratio 0.5 A conductive roller was produced basically in the same manner as in Example 1 except that a glass transition temperature of 34 ° C. was used.

(Comparative Example 3)
Instead of polyurethane beads “RV-600T”, polymethylmethacrylate beads “FH-S010” (trade name, manufactured by Toyobo Co., Ltd., reactive group content 0 mass%, 10% fine compression strength 27 MPa, average particle size 10 μm, average particle size A conductive roller was produced basically in the same manner as in Example 1 except that the diameter ratio 0.5) was used.

(Slip angle measurement)
In each manufactured conductive roller, the slip angle was measured by the method described above. The results are shown in Table 1.

(Measurement of surface characteristics)
In each conductive roller, the average interval Sm of the unevenness, the arithmetic average roughness Ra, and the skewness Rsk of the contour curve were measured by the above-described method. The results are shown in Table 1.

(Evaluation of dispersion state of resin beads)
For each conductive roller, the number of resin beads dispersed was determined by the method described above. The results are shown in Table 1.

(Initial filming evaluation)
Each conductive roller was evaluated for the presence and extent of initial filming as follows. Specifically, each manufactured conductive roller is incorporated as a developing roller in a magenta toner cartridge of an image forming apparatus (trade name “MICROLINE 1032PS”, manufactured by Oki Data Corporation), and NN (temperature 23 ° C., relative humidity 50%) Under the environment, 2K (2000 sheets) was printed under a 1% duty condition. Thereafter, the conductive roller was taken out, and the developer attached to the non-woven fabric in which half of the surface of the conductive roller in the longitudinal direction was soaked with alcohol was wiped off. The conductive roller was again incorporated into the magenta cartridge as a developing roller, and one 2-by-2 halftone image was printed.
In the conductive roller, X-Rite Spectrodensitometer represents the print density of the 2by2 halftone image printed on the surface on which the developer is wiped off and the 2by2 halftone image printed on the surface on which the developer is not wiped off, respectively. (X-Rite, Inc.). The case where the difference in density between the two was 0.0 to 0.05 was “◎”, the case where it was 0.06 to 0.10 was “◯”, and the case where it was 0.11 or more was “×”. It was. The results are shown in Table 1.

(Filming evaluation after durable printing)
Each conductive roller was subjected to a durability printing test and evaluated for the presence and extent of long-term filming as follows. Specifically, each manufactured conductive roller is incorporated as a developing roller in a magenta toner cartridge of an image forming apparatus (trade name “MICROLINE 1032PS”, manufactured by Oki Data Corporation), and NN (temperature 23 ° C., relative humidity 50%) Under the environment, 10K (10,000 sheets) was printed under the 1% duty condition. Thereafter, the conductive roller was taken out, and the developer attached to the non-woven fabric in which half of the surface of the conductive roller in the longitudinal direction was soaked with alcohol was wiped off. The conductive roller was again incorporated into the magenta cartridge as a developing roller, and one 2-by-2 halftone image was printed.
In the conductive roller, X-Rite Spectrodensitometer represents the print density of the 2by2 halftone image printed on the surface on which the developer is wiped off and the 2by2 halftone image printed on the surface on which the developer is not wiped off, respectively. (X-Rite, Inc.). The case where the difference in density between the two was 0.0 to 0.05 was “◎”, the case where it was 0.06 to 0.10 was “◯”, and the case where it was 0.11 or more was “×”. It was. The results are shown in Table 1.

As shown in Table 1, each of the conductive rollers of the examples is formed of a cured product of a urethane resin composition containing polyurethane beads having a blocked isocyanate group as a reactive group and a urethane preparation component. It was possible to prevent long-term filming.
On the other hand, the conductive roller of the comparative example is formed of a cured product of a urethane resin composition containing resin beads not having a reactive group and a urethane preparation component, and can prevent the occurrence of long-term filming. There wasn't.

DESCRIPTION OF SYMBOLS 1 Conductive roller 2 Shaft body 3 Elastic layer 4 Resin layer 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 Developer 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 (8)

A conductive roller having an elastic layer and a resin layer formed on the outer periphery of the elastic layer,
A resin layer forming composition, wherein the resin layer comprises a monomer component of a polymer different from the polymer forming the elastic layer, and resin beads having a reactive group that reacts with the monomer component A conductive roller formed of a cured product.   The conductive roller according to claim 1, wherein an average particle diameter of the resin beads is 1 to 40 μm.   3. The conductive roller according to claim 1, wherein 1 to 90 resin beads are dispersed in a 35 μm × 50 μm region of the resin layer.   The conductive roller according to claim 1, wherein the sliding angle is 1 to 70 °.   The conductive roller according to claim 1, wherein the elastic layer is made of polysiloxane, and the resin layer is made of polyurethane.   The conductive roller according to claim 1, wherein the reactive group is a blocked isocyanate group.   A developing device comprising the conductive roller according to claim 1 as a developing roller.   An image forming apparatus comprising the conductive roller according to claim 1 as a developing roller.

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